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BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a process for preparing azo coloring materials, i.e., dyes and pigments. More specifically, this invention relates to an improved process for preparing azo dyes and pigments characterized by improved consistency and reproducibility of the dyes and pigments produced thereby. 2. Description of the Prior Art Azo coloring materials have traditionally been prepared on a commercial scale by a multi-step procedure. That procedure involves preparing an appropriate aqueous solution or dispersion of a diazonium salt of a primary amino compound in one reaction vessel, preparing an appropriate aqueous solution or dispersion of a coupling compound in a second vessel and either adding one of these masses to the other or mixing them in a third vessel. It is well known in the prior art to employ phenols, naphthols, etc., and particularly beta-naphthols and beta-naphthol substituted compounds as couplers in the production of azo dyes and pigments. However, production of azo dyes and pigments by the conventional prior art processes often results in batch to batch inconsistencies and lack of reproducibility of the azo dye or pigment produced. It is a purpose of the instant invention to provide a process for producing azo dyes and pigments, by coupling with beta-naphthols and beta-naphthol substituted compounds, characterized by improved consistency and reproducibility of the product. ______________________________________Pertinent Prior ArtReferencesPatent No. Issued Inventor Assignee______________________________________4,046,754 9/6/77 Meininger et al Hoechst3,793,305 2/19/74 Balon DuPont4,014,866 3/29/77 Henning BASF______________________________________ SUMMARY OF THE INVENTION This invention is directed particularly to a process for coupling beta-naphthol and beta-naphthol substituted compounds with a diazotized amine wherein after the coupler and the diazotized amine are mixed together, the pH is increased in two steps. More specifically, the pH is increased to about 1.0 to 4.0 by the addition of a strong base followed by a further increase to about 5.0 to 10.0 with a weak base. DESCRIPTION OF THE INVENTION The present invention comprises a process for coupling beta-naphthol with a diazotized amine as follows: 1. (a) Dissolving a beta-naphthol in water with a strong base (b) Precipitating the beta-naphthol with a strong acid and (c) Cooling the slurry to about 0° C. to 15° C. 2. Adding a diazotized amine to the beta-naphthol solution and 3. (a) Increasing the pH to about 1.0 to 4.0 with a strong base and (b) Further increasing the pH to about 5.0 to 10.0 with a weak base. As used herein, the expression "beta-naphthol" includes beta-naphthol itself and substituted beta-naphthols. The latter include alkyl derivatives of beta-naphthol which contain alkyl groups having more than 3 carbon atoms, such as butyl, isobutyl, isoamyl, hexyl and octyl groups. Polyalkyl derivatives of beta-naphthol, such as diamyl-2-naphthol are also useful. The beta-naphthol may also be substituted with other groups such as sulfonic acid groups. These naphthols can be prepared by various processes known to the art and can be used in varying stages of purity. Particularly preferred beta-naphthols are beta-naphthol and beta-oxy-naphthoic acid for the production of a red dye or pigment. For the production of yellow dyes and pigments, orthochloroaceto acetanilide and ortho-aceto acetanisidide are particularly preferred. The beta-naphthol is slurried in water at room temperature and the temperature raised to about 55° C. to 65° C. by conventional heating means. The strong base, preferably sodium hydroxide or potassium hydroxide, is added until the beta-naphthol is dissolved generally at a pH of about 10 to 12. When the beta-naphthol is fully dissolved, a strong acid, preferably HCL or H 2 SO 4 , is added until the beta-naphthol is fully reprecipitated which is generally at a pH of about 0.5 to 2.0 after which the solution is cooled to about 0° C. to 15° C. In a separate container, the diazotized amine is prepared in the conventional manner. In general it is prepared by bringing together in a liquid reaction medium a diazotizable amine and a diazotizing agent. Any aromatic or aliphatic primary amine may be employed, all as well known to those skilled in the art. Typical diazotizable amines include carbocyclic and tetracyclic aromatic amines, nuclearly unsubstituted or nuclearly substituted with one or more groups, for example, nitro, chlorine, bromine, alkyl, alkoxy, cyano carboxy, keto, arylazo, acylamino, sulfo and 'onium groups. These subsistuents may be present in combination in an aromatic amine which is preferably an aniline. Other amines are amines of the benzene series such as aniline, the toluidines the xylidines, anisidine, the chloro and nitro derivatives of aniline and toluidine such as chloroaniline, nitroaniline, chlorotoluidine, nitrotoluidine and the like; amino compounds of the naphthalene series such as alpha-naphthylamine and its derivatives; the diaminodiphenylamines such as benzidine, toluidine and dianisidine. Practically every aromatic primary amine is a potential diazo component. The value of an amine is determined chiefly by the properties of the dye prepared from it. Cost of amine, ease of diazotization, stability of the diazonium salt, and final cost of the dye are factors which influence the selection of an amine. The preferred diazotization agent is nitrous acid and its derivatives. One preferred method of preparing a diazotized amine is to add the amine to water in amount of about 9 to 15 percent by weight then raise the pH by addition of an amount of a strong base such as sodium hydroxide sufficient to dissolve the amine. This generally results in a pH of about 9.0 to 12.0. The temperature is generally about 65° C. to 80° C. A strong acid is then added until a pH of less than about 2 is obtained, a preferred acid being HCL or H 2 SO 4 . The solution is then cooled to about -5° to 15° C. with a slight excess (i.e., about 3 percent molar excess) of sodium nitrite added. The excess sodium nitrite is then destroyed with sulfamic acid. The preferred molar proportions of diazotized amine and beta-naphthol are about 1:1. The diazotized amine and coupler are then mixed together, with the temperature maintained at about 5° C. to 20° C. An aqueous solution of a strong base such as sodium hydroxide or potassium hydroxide is added until a pH of about 1.0 to 4.0 is achieved. This solution, preferably contains about 3 percent by weight of the base in water. This addition must be done carefully to avoid having the pH exceed 4.0. The time required to perform this step is not critical, however, generally it should require about 1 to 2 minutes. When this pH range is achieved, a weak base is added. As used herein the expression "weak base" generally means any base that is weaker than the well known strong bases such as sodium hydroxide or potassium hydroxide. Examples of suitable weak bases are ammonia or sodium carbonate and preferably sodium acetate. Generally an aqueous solution of about 1 percent of the weak base is added until a pH of about 5.0 to 10.0 is achieved. This should be done at such a rate that the desired pH is reached in about 5 to 7 minutes after the initial start of the base addition. However, time is not critical. Where a high ultimate pH, i.e., 8-10 is desired, a further strong base addition may be necessary after the weak base addition. However, in all cases it is necessary to follow the initial strong base addition with a weak base in order to control the final pH since with the use of strong base alone it is difficult to avoid an excessive final pH. The reactin is completed by raising the temperature of the reaction to about 95° C. varying the time period for raising the temperature according to the pigment characteristics desired all of which is well known to those skilled in the art. In some cases it may be desirable to add barium chloride or calcium chloride, etc., during heat-up to convert the pigment to a different salt form. The invention will be described in greater detail in conjunction with the following specific examples in which all parts are by weight and all temperatures in degrees centigrade unless otherwise specified. EXAMPLE 1 140 grams of 100 percent 2-chloro-5-amino-p-toluene sulfonic acid and 94 grams of hydrochloric acid are added to 1 liter of water in a battery jar. The mixture is stirred for 30 minutes and cooled to 10° C. with ice. 44.8 grams of sodium nitrite is then dissolved in 300 ml of water and slowly added to the above mixture followed by stirring for 1 hour at 10° C. Sulfamic acid is then added to destroy the excess nitrite. 94.6 grams of beta-naphthol, 65.0 grams of sodium hydroxide (50 percent aqueous solution) are added to 370 ml of water in a 600 ml beaker. The mixture is stirred and heated to 60° C. When everything is dissolved, ice is added to cool to a temperature of 10° C. 60 grams of hydrochloric acid (36 percent aqueous solution) is then added until a pH of 0.9 to 1.0 is obtained. The mixture is then stirred for 15 minutes at 10° C. The diazo slurry and the coupler slurry are mixed together at 10° C. at a pH of less than 1.0. The mixture is stirred for 10 minutes after which a 3 percent by weight aqueous solution of sodium hydroxide is added over a period of 1 to 2 minutes until a pH of 2.2 is obtained. A 1.0 percent aqueous solution of sodium acetate is then immediately added over a 5 to 7 minute period until a pH of 5.5 is obtained. The mixture is then heated to 75° C. and aqueous BaCL 2 solution (20%) is added. It is then heated further to 95° C. and held for 5 minutes after which it is cooled to 60° C. with ice and filtered whereby the pigment is isolated. EXAMPLE 2 The procedure of Example 1 is followed with the exception that in preparing the coupler 96.0 grams of 3-hydroxy-2-naphthoic acid is substituted for the beta-naphthol. EXAMPLE 3 The procedure of Example 1 is followed with the exception that in preparing the diazo compound 140 grams of 100 percent 1-napthylamine-2-sulfonic acid is substituted for the 2-chloro-5-amino-p-toluene sulfonic acid. EXAMPLE 4 The procedure of Example 1 is followed with the exception that a tetra azo compound is employed in lieu of a diazo compound. This is prepared by adding 2.72 grams of dichlorobenzidine and 3.77 grams of hydrochloric acid to 18.9 ml of water in a 2 liter beaker. This mixture is stirred for 1 hour after which 1.5 grams of sodium nitrite dissolved in 30 ml of water is added. Excess sodium nitrite is destroyed with sulfamic acid. EXAMPLE 5 The procedure of Example 1 is followed with the exception that 2-chloro-5-amino-ethyl benzene sulfonic acid is substituted for the 2-chloro-5-amino-p-toluene sulfonic acid.
The present invention relates to a process for coupling beta-naphthol with a diazotized amine as follows: 1. (a) Dissolving a beta-naphthol in water with a strong base (b) Precipitating the beta-naphthol with a strong acid and (c) Cooling the slurry. 2. Adding a diazotized amine to the beta-naphthol solution and 3. Increasing the pH in two steps, first with a strong base and then with a weak base.
Summarize the patent information, clearly outlining the technical challenges and proposed solutions.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention This invention relates to a process for preparing azo coloring materials, i.e., dyes and pigments.", "More specifically, this invention relates to an improved process for preparing azo dyes and pigments characterized by improved consistency and reproducibility of the dyes and pigments produced thereby.", "Description of the Prior Art Azo coloring materials have traditionally been prepared on a commercial scale by a multi-step procedure.", "That procedure involves preparing an appropriate aqueous solution or dispersion of a diazonium salt of a primary amino compound in one reaction vessel, preparing an appropriate aqueous solution or dispersion of a coupling compound in a second vessel and either adding one of these masses to the other or mixing them in a third vessel.", "It is well known in the prior art to employ phenols, naphthols, etc.", ", and particularly beta-naphthols and beta-naphthol substituted compounds as couplers in the production of azo dyes and pigments.", "However, production of azo dyes and pigments by the conventional prior art processes often results in batch to batch inconsistencies and lack of reproducibility of the azo dye or pigment produced.", "It is a purpose of the instant invention to provide a process for producing azo dyes and pigments, by coupling with beta-naphthols and beta-naphthol substituted compounds, characterized by improved consistency and reproducibility of the product.", "______________________________________Pertinent Prior ArtReferencesPatent No. Issued Inventor Assignee______________________________________4,046,754 9/6/77 Meininger et al Hoechst3,793,305 2/19/74 Balon DuPont4,014,866 3/29/77 Henning BASF______________________________________ SUMMARY OF THE INVENTION This invention is directed particularly to a process for coupling beta-naphthol and beta-naphthol substituted compounds with a diazotized amine wherein after the coupler and the diazotized amine are mixed together, the pH is increased in two steps.", "More specifically, the pH is increased to about 1.0 to 4.0 by the addition of a strong base followed by a further increase to about 5.0 to 10.0 with a weak base.", "DESCRIPTION OF THE INVENTION The present invention comprises a process for coupling beta-naphthol with a diazotized amine as follows: 1.", "(a) Dissolving a beta-naphthol in water with a strong base (b) Precipitating the beta-naphthol with a strong acid and (c) Cooling the slurry to about 0° C. to 15° C. 2.", "Adding a diazotized amine to the beta-naphthol solution and 3.", "(a) Increasing the pH to about 1.0 to 4.0 with a strong base and (b) Further increasing the pH to about 5.0 to 10.0 with a weak base.", "As used herein, the expression "beta-naphthol"", "includes beta-naphthol itself and substituted beta-naphthols.", "The latter include alkyl derivatives of beta-naphthol which contain alkyl groups having more than 3 carbon atoms, such as butyl, isobutyl, isoamyl, hexyl and octyl groups.", "Polyalkyl derivatives of beta-naphthol, such as diamyl-2-naphthol are also useful.", "The beta-naphthol may also be substituted with other groups such as sulfonic acid groups.", "These naphthols can be prepared by various processes known to the art and can be used in varying stages of purity.", "Particularly preferred beta-naphthols are beta-naphthol and beta-oxy-naphthoic acid for the production of a red dye or pigment.", "For the production of yellow dyes and pigments, orthochloroaceto acetanilide and ortho-aceto acetanisidide are particularly preferred.", "The beta-naphthol is slurried in water at room temperature and the temperature raised to about 55° C. to 65° C. by conventional heating means.", "The strong base, preferably sodium hydroxide or potassium hydroxide, is added until the beta-naphthol is dissolved generally at a pH of about 10 to 12.", "When the beta-naphthol is fully dissolved, a strong acid, preferably HCL or H 2 SO 4 , is added until the beta-naphthol is fully reprecipitated which is generally at a pH of about 0.5 to 2.0 after which the solution is cooled to about 0° C. to 15° C. In a separate container, the diazotized amine is prepared in the conventional manner.", "In general it is prepared by bringing together in a liquid reaction medium a diazotizable amine and a diazotizing agent.", "Any aromatic or aliphatic primary amine may be employed, all as well known to those skilled in the art.", "Typical diazotizable amines include carbocyclic and tetracyclic aromatic amines, nuclearly unsubstituted or nuclearly substituted with one or more groups, for example, nitro, chlorine, bromine, alkyl, alkoxy, cyano carboxy, keto, arylazo, acylamino, sulfo and 'onium groups.", "These subsistuents may be present in combination in an aromatic amine which is preferably an aniline.", "Other amines are amines of the benzene series such as aniline, the toluidines the xylidines, anisidine, the chloro and nitro derivatives of aniline and toluidine such as chloroaniline, nitroaniline, chlorotoluidine, nitrotoluidine and the like;", "amino compounds of the naphthalene series such as alpha-naphthylamine and its derivatives;", "the diaminodiphenylamines such as benzidine, toluidine and dianisidine.", "Practically every aromatic primary amine is a potential diazo component.", "The value of an amine is determined chiefly by the properties of the dye prepared from it.", "Cost of amine, ease of diazotization, stability of the diazonium salt, and final cost of the dye are factors which influence the selection of an amine.", "The preferred diazotization agent is nitrous acid and its derivatives.", "One preferred method of preparing a diazotized amine is to add the amine to water in amount of about 9 to 15 percent by weight then raise the pH by addition of an amount of a strong base such as sodium hydroxide sufficient to dissolve the amine.", "This generally results in a pH of about 9.0 to 12.0.", "The temperature is generally about 65° C. to 80° C. A strong acid is then added until a pH of less than about 2 is obtained, a preferred acid being HCL or H 2 SO 4 .", "The solution is then cooled to about -5° to 15° C. with a slight excess (i.e., about 3 percent molar excess) of sodium nitrite added.", "The excess sodium nitrite is then destroyed with sulfamic acid.", "The preferred molar proportions of diazotized amine and beta-naphthol are about 1:1.", "The diazotized amine and coupler are then mixed together, with the temperature maintained at about 5° C. to 20° C. An aqueous solution of a strong base such as sodium hydroxide or potassium hydroxide is added until a pH of about 1.0 to 4.0 is achieved.", "This solution, preferably contains about 3 percent by weight of the base in water.", "This addition must be done carefully to avoid having the pH exceed 4.0.", "The time required to perform this step is not critical, however, generally it should require about 1 to 2 minutes.", "When this pH range is achieved, a weak base is added.", "As used herein the expression "weak base"", "generally means any base that is weaker than the well known strong bases such as sodium hydroxide or potassium hydroxide.", "Examples of suitable weak bases are ammonia or sodium carbonate and preferably sodium acetate.", "Generally an aqueous solution of about 1 percent of the weak base is added until a pH of about 5.0 to 10.0 is achieved.", "This should be done at such a rate that the desired pH is reached in about 5 to 7 minutes after the initial start of the base addition.", "However, time is not critical.", "Where a high ultimate pH, i.e., 8-10 is desired, a further strong base addition may be necessary after the weak base addition.", "However, in all cases it is necessary to follow the initial strong base addition with a weak base in order to control the final pH since with the use of strong base alone it is difficult to avoid an excessive final pH.", "The reactin is completed by raising the temperature of the reaction to about 95° C. varying the time period for raising the temperature according to the pigment characteristics desired all of which is well known to those skilled in the art.", "In some cases it may be desirable to add barium chloride or calcium chloride, etc.", ", during heat-up to convert the pigment to a different salt form.", "The invention will be described in greater detail in conjunction with the following specific examples in which all parts are by weight and all temperatures in degrees centigrade unless otherwise specified.", "EXAMPLE 1 140 grams of 100 percent 2-chloro-5-amino-p-toluene sulfonic acid and 94 grams of hydrochloric acid are added to 1 liter of water in a battery jar.", "The mixture is stirred for 30 minutes and cooled to 10° C. with ice.", "44.8 grams of sodium nitrite is then dissolved in 300 ml of water and slowly added to the above mixture followed by stirring for 1 hour at 10° C. Sulfamic acid is then added to destroy the excess nitrite.", "94.6 grams of beta-naphthol, 65.0 grams of sodium hydroxide (50 percent aqueous solution) are added to 370 ml of water in a 600 ml beaker.", "The mixture is stirred and heated to 60° C. When everything is dissolved, ice is added to cool to a temperature of 10° C. 60 grams of hydrochloric acid (36 percent aqueous solution) is then added until a pH of 0.9 to 1.0 is obtained.", "The mixture is then stirred for 15 minutes at 10° C. The diazo slurry and the coupler slurry are mixed together at 10° C. at a pH of less than 1.0.", "The mixture is stirred for 10 minutes after which a 3 percent by weight aqueous solution of sodium hydroxide is added over a period of 1 to 2 minutes until a pH of 2.2 is obtained.", "A 1.0 percent aqueous solution of sodium acetate is then immediately added over a 5 to 7 minute period until a pH of 5.5 is obtained.", "The mixture is then heated to 75° C. and aqueous BaCL 2 solution (20%) is added.", "It is then heated further to 95° C. and held for 5 minutes after which it is cooled to 60° C. with ice and filtered whereby the pigment is isolated.", "EXAMPLE 2 The procedure of Example 1 is followed with the exception that in preparing the coupler 96.0 grams of 3-hydroxy-2-naphthoic acid is substituted for the beta-naphthol.", "EXAMPLE 3 The procedure of Example 1 is followed with the exception that in preparing the diazo compound 140 grams of 100 percent 1-napthylamine-2-sulfonic acid is substituted for the 2-chloro-5-amino-p-toluene sulfonic acid.", "EXAMPLE 4 The procedure of Example 1 is followed with the exception that a tetra azo compound is employed in lieu of a diazo compound.", "This is prepared by adding 2.72 grams of dichlorobenzidine and 3.77 grams of hydrochloric acid to 18.9 ml of water in a 2 liter beaker.", "This mixture is stirred for 1 hour after which 1.5 grams of sodium nitrite dissolved in 30 ml of water is added.", "Excess sodium nitrite is destroyed with sulfamic acid.", "EXAMPLE 5 The procedure of Example 1 is followed with the exception that 2-chloro-5-amino-ethyl benzene sulfonic acid is substituted for the 2-chloro-5-amino-p-toluene sulfonic acid." ]
BACKGROUND 1. Field of the Invention The present invention relates to a temperature detecting circuit and, more particularly, to a temperature detecting circuit that can be exactly implemented since trimming is possible depending on variation in process or voltage and that can significantly reduce consumption of the standby current since the refresh period is differentiated depending on temperature, in such a manner that the width of variation in temperature that can be detected by the temperature detecting circuit can be widened using a plurality of detectors, the status of the plurality of the detectors can be detected at the outside by an encoder, and one of the detectors that can detect correct temperature information by transferring fuse trimming information from the outside to the detecting means via the select means. 2. Discussion of Related Art In semiconductor devices, if a device requiring a periodical refresh so as to keep data is needed, a large amount of standby current is necessary for a self-refresh. The refresh period that is actually required, however, very differs depending on temperature. If temperature is detected and the refresh period is varied depending on temperature, the standby current can be significantly reduced. The exactness of a common temperature detecting circuit, however, is lowered depending on variation in external conditions such as process, voltage, and the like. FIG. 1 is a block diagram illustrating the construction of a conventional temperature detecting circuit. A first delay means 11 receives an input signal (IN) as an input to output a reference signal (ref) depending on temperature that will be detected without being influenced by variation in operating environments such as change in process, voltage, temperature, etc. A second delay means 12 outputs a delay signal (tem) whose delay value is changed depending on variation in temperature. A detector 13 receives the reference signal (ref) from the first delay means 11 and the delay signal (tem) from the second delay means 12 , as an input and then outputs (dout) a detecting signal (det) indicating whether the delay signal (tem) is lower or higher the reference signal (ref) to the outside through a DQ buffer 14 . As such, the detection width of temperature is controlled by correcting the delay width of the first delay means 11 or the second delay means 12 using the data outputted via the DQ buffer 14 . In the conventional temperature detecting circuit constructed above, however, since only one detector is employed, the width of variation in temperature that can be detected depending on variation in process or voltage is limited. Therefore, if the width of variation in temperature that can be actually detected by a device is large, the device fails to serve as the temperature detecting circuit. SUMMARY OF THE INVENTION The present invention is contrived to solve the aforementioned problems. The present invention is directed to provide a temperature detecting circuit that can widely control the width of variation in temperature depending on variation in process or voltage by use of a plurality of detectors. According to a preferred embodiment of the present invention, there is provided a temperature detecting circuit wherein the state of a plurality of detectors can be detected externally using an encoder. Further, the present invention is to provide a temperature detecting circuit that can select a detector capable of detecting correct temperature information by allowing fuse trimming information to be transferred via a select means so that correct temperature information can be transferred to a device from the outside. According to a preferred embodiment of the present invention, there is provided A temperature detecting circuit, comprising: a first delay means for outputting a reference signal that is delayed by some time according to an input signal without being affected by variation in temperature; a second delay means for delaying the input signal in different delay time according to variation in temperature to generate a plurality of delay signals; a detecting means for comparing the reference signal and the plurality of the delay signals, respectively, to output a plurality of detecting signals; an encoder for encoding the plurality of the detecting signals into given numbers of output signals; a buffer for outputting the output signal of the encoder to the outside and receiving a control signal from the outside as an input; and a select means that can be programmed according to the control signal, for selecting one of the detecting signals according to a program state. One aspect of the present invention is to provide a temperature detecting circuit, comprising: a first delay means for outputting a reference signal that is delayed by some time according to an input signal without being affected by variation in temperature; a second delay means for delaying the input signal in different delay time according to variation in temperature to generate a plurality of delay signals; a detecting means having a plurality of detectors, wherein the detector compares the reference signal and the plurality of the delay signals, respectively, to output a plurality of detecting signals; an encoder for encoding the plurality of the detecting signals into given numbers of output signals; a buffer for outputting the output signal of the encoder to the outside and receiving a control signal from the outside as an input; and a select means having a plurality of fuses that can be cut, for cutting the fuses according to the control signal and selecting one of the plurality of the detectors according to the fuse signal depending on the state of the fuse. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which: FIG. 1 is a block diagram illustrating the construction of a conventional temperature detecting circuit; FIG. 2 is a block diagram illustrating the construction of a temperature detecting circuit according to the present invention; FIG. 3 is a block diagram illustrating the detailed construction of the second delay means shown in FIG. 2 according to an embodiment of the present invention; FIG. 4 is a block diagram illustrating the detailed construction of the detecting means shown in FIG. 2 according to an embodiment of the present invention; FIG. 5 is a block diagram illustrating the detailed construction of the detector shown in FIG. 4 according to an embodiment of the present invention; FIG. 6 is a block diagram illustrating the detailed construction the encoder shown in FIG. 2 according to an embodiment of the present invention; and FIGS. 7A and 7B are block diagrams illustrating the detailed construction of the select means shown in FIG. 2 according to an embodiment of the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention will now be described in detail in connection with preferred embodiments with reference to the accompanying drawings, in which like reference numerals are used to identify the same or similar parts. FIG. 2 is a block diagram illustrating the construction of a temperature detecting circuit according to the present invention. A first delay means 21 outputs a reference signal (ref) that is delayed by some time according to an input signal (IN) without being affected by variation in operating environments such as variation in temperature, etc. The reference signal (ref) is fixed to temperature to be detected and becomes a signal indicating that temperature. A second delay means 22 changes the value of the input signal (IN) that is delayed according to on variation in temperature. The second delay means 22 outputs a delay signal corresponding temperature to be detected and a plurality of delay signals (tem) corresponding to temperature for which a sufficient margin is taken into consideration on the basis of that temperature to be detected. A detecting means 23 consists of a plurality of detectors. Each of the detectors uses the reference signal (ref) inputted from the first delay means 21 and the plurality of the delay signals (tem) inputted from the second delay means 22 to detect whether the delay signal (tem) is higher or lower than the reference signal (ref), and then outputs a detecting signal (det). The detecting signal (det) outputted from the detecting means 23 has temperature information that is currently being measured in a device. In order to output such temperature information to the outside, the encoder 24 encodes temperature information to output a plurality of output signals (dout). The plurality of the output signals (dout) outputted by the encoder 24 are provided as information to the outside through a DQ buffer 26 . It is confirmed whether such information matches external environments. At this time, if actual temperature and temperature that is being recognized in the device are different, fuse information (Fuse Info) is provide to a select means 25 so that the detecting means 23 within the device that actually recognizes external temperature can be selected. The select means 25 may have a programmable fuse. The select means 25 cuts the fuse depending on fuse information (Fuse Info), combines signals depending on the result to produce information for allowing the means 25 to select one detector that must be used by the device, and then transfers such information to the detecting means 23 . Based on information thus transferred, only one of the plurality of the detectors in the detecting means 23 is enabled and remaining detectors are disabled. Only the signal detected in the selected detector is thus outputted through the encoder 24 and the DQ buffer 26 . FIG. 3 is a block diagram illustrating the detailed construction of the second delay means shown in FIG. 2 according to an embodiment of the present invention. An inverter chain 31 delays the input signal (IN) by some time to output a first delay signal (tem 0 ). The first delay signal (tem 0 ) is delayed through first and second inverters I 31 and I 32 to become a second delay signal (tem 1 ). The second delay signal (tem 1 ) is delayed through third and fourth inverters I 33 and I 34 to become a third delay signal (tem 2 ). The third delay signal (tem 2 ) is delayed through fifth and sixth inverters I 35 and I 36 to become a fourth delay signal (tem 3 ). In the above, the delay value is extended to some degree depending on a given difference in temperature, by means of the first and second inverters I 31 and I 32 , the third and fourth inverters I 33 and I 34 , and the fifth and sixth inverters I 35 and I 36 . It is thus possible to identify the difference in temperature. FIG. 4 is a block diagram illustrating the detailed construction of the detecting means 23 shown in FIG. 2 according to an embodiment of the present invention. A first detector 41 uses the first delay signal (tem 0 ) outputted from the second delay means and the reference signal (ref) outputted from the first delay means to output a first detecting signal (det 0 ). A second detector 42 uses the second delay signal (tem 1 ) outputted from the second delay means and the reference signal (ref) outputted from the first delay means to output a second detecting signal (det 1 ). A third detector 43 uses the third delay signal (tem 2 ) outputted from the second delay means and the reference signal (ref) outputted from the first delay means to output a third detecting signal (det 2 ). A fourth detector 44 uses the fourth delay signal (tem 3 ) outputted from the second delay means and the reference signal (ref) outputted from the first delay means to output a fourth detecting signal (det 3 ). A first transfer gate T 41 outputs the first detecting signal (det 0 ) as the final detecting signal (last — det) according to the first output signal (out 0 ) of the encoder and its inverse signal (outb 0 ). A second transfer gate T 42 outputs the second detecting signal (det 1 ) as the final detecting signal (last — det) according to the second output signal (out 1 ) of the encoder and its inverse signal (outb 1 ). A third transfer gate T 43 outputs the third detecting signal (det 2 ) as the final detecting signal (last — det) according to the third output signal (out 2 ) of the encoder and its inverse signal (outb 2 ). A fourth transfer gate T 44 outputs the fourth detecting signal (det 3 ) as the final detecting signal (det) according to the fourth output signal (out 3 ) of the encoder and its inverse signal (outb 3 ). In the detecting means constructed above, at the initial stage, the first to fourth output signals (out 0 to out 3 ) are encoded by the encoder 24 and are then outputted to the outside by the DQ buffer 26 . However, only one of the first to fourth transfer gates T 41 to T 44 is turned on according to the output signal of the select means 25 by fuse information (Fuse Info) externally inputted, and only one of the detecting signals (det 0 to det 3 ) of the first to fourth detectors 41 to 44 is outputted to the outside. FIG. 5 is a block diagram illustrating the detailed construction of the detector shown in FIG. 4 according to an embodiment of the present invention. A first NAND gate 51 performs a NAND operation for an input signal (in) and the output signal of a second NAND gate 52 . A second NAND gate 52 performs a NAND operation for the reference signal (ref) and the output signal of the first NAND gate 51 . In the above, the input signal (in) is one of the first to fourth delay signals outputted from the second delay means and the reference signal (ref) is a signal inputted from the first delay means. The first transfer gate T 51 is driven according to a control signal (act) and its inverse signal (actb) to transfer the output signal of the first NAND gate 51 . Further, a latch 53 having first and second inverters I 51 and I 52 latches the output signal of the first NAND gate 51 that is transferred via the first transfer gate T 51 . A third inverter I 53 inverts the data that was latched by the latch 53 to output an inverse signal, which is a detecting signal (det). FIG. 6 is a block diagram illustrating the detailed construction the encoder 24 shown in FIG. 2 according to an embodiment of the present invention. A first inverter I 61 inverts the second detecting signal (det 2 ) outputted from the second detector of the detecting means to produce a first output signal (dout 0 ). A first NAND gate 61 performs a NAND operation for the output signal of the first inverter I 61 and the first detecting signal (det 1 ) outputted from the first detector of the detecting means. A second NAND gate 62 performs a NAND operation for the second detecting signal (det 2 ) and the third detecting signal (det 3 ) outputted from the third detector of the detecting means. A NOR gate 63 performs a NOR operation for the output signals of the first NAND gate 61 and the second NAND gate 62 to output a second output signal (dout 1 ). FIG. 7A and 7B are block diagrams illustrating the detailed construction of the select means 25 shown in FIG. 2 according to an embodiment of the present invention, wherein FIG. 7A is a circuit diagram illustrating a fuse signal generating means and FIG. 7B is a circuit diagram illustrating a select signal generating means. Referring to FIG. 7A , a first fuse F 71 is connected between the power supply terminal (Vcore) and a first node Q 71 . A first NMOS transistor N 71 ) driven by an enable signal (enable) and a second NMOS transistor N 72 driven by the potential of a second node Q 72 are connected in parallel between the first node Q 71 and the ground terminal (Vss). A first inverter I 71 inverts the potential of the first node Q 71 to decide the potential of the second node Q 72 . The potential of the second node Q 72 becomes a first fuse signal (fu 0 ). Furthermore, the potential of the second node Q 72 is inverted through the second inverter I 72 and is then outputted as a first fuse bar signal (fu 0 — b). Meanwhile, a second fuse F 72 is connected between the power supply terminal (Vcore) and a third node Q 73 . A third NMOS transistor N 73 driven by the enable signal (enable) and a fourth NMOS transistor N 74 driven by the potential of a fourth node Q 74 are connected in parallel between the third node Q 73 and the ground terminal (Vss). A third inverter I 73 inverts the potential of the third node Q 73 to decide the potential of the fourth node Q 74 and the potential of the fourth node Q 74 becomes a second fuse signal (fu 1 ). Furthermore, the potential of the fourth node Q 74 is inverted through the fourth inverter I 74 and is then outputted as a second fuse bar signal (fu 1 — b). By reference to FIG. 7B , a first NAND gate 71 performs a NAND operation for the first fuse bar signal (fu 0 — b) and the second fuse bar signal (fu 1 — b) and a fifth inverter I 75 inverts the output signal of the first NAND gate 71 to output a third output signal (out 2 ). A second NAND gate 72 performs a NAND operation for the first fuse bar signal (fu 0 — b) and the second fuse signal (fu 1 ) and a sixth inverter I 76 inverts the output signal of the second NAND gate 72 to output a first output signal (out 0 ). A third NAND gate 73 performs a NAND operation for the first fuse signal (fu 0 ) and the second fuse bar signal (fu 1 — b) and a seventh inverter I 77 inverts the output signal of the third NAND gate 73 to output a fourth output signal (out 3 ). Furthermore, a fourth NAND gate 74 performs a NAND operation for the first fuse signal (fu 0 ) and the second fuse signal (fu 1 ) and an eighth inverter I 78 inverts the output signal of the fourth NAND gate 74 to output a second output signal (out 1 ). The select means constructed above selectively cuts the first and second fuses F 71 and F 72 according to fuse information (Fuse Info) and, according to its result, selects one of the plurality of the detectors 31 to 34 constituting the detecting means 23 . The operation when only the fuse F 71 is cut according to fuse information (Fuse Info) will now be described by way of an example. If the first NMOS transistor N 71 is turned on by the enable signal (enable), the first node Q 71 keeps a LOW state since the first fuse F 71 is cut. The potential of the first node Q 71 keeping the LOW state is inverted to a HIGH state through the first inverter I 71 and the potential of the second node Q 72 keeping the HIGH state becomes the potential of the first fuse signal (fu 0 ). Further, the second NMOS transistor N 72 is turned on by the potential of the second node Q 72 and the potential of the second node Q 72 is inverted to a LOW state through the second inverter I 72 to become the potential of the first fuse bar signal (fu 0 — b). Meanwhile, if the third NMOS transistor N 73 is turned on by the enable signal (enable), the third node Q 73 keeps a HIGH state since the second fuse F 72 keeps a normal state. The potential of the third node Q 73 keeping the HIGH state is inverted to a LOW state through the third inverter I 73 and the potential of the fourth node Q 74 keeping the LOW state becomes the potential of the second fuse signal (fu 1 ). Furthermore, the fourth NMOS transistor N 74 is turned off by the potential of the fourth node Q 74 and the potential of the fourth node Q 74 is inverted to a HIGH state through the fourth inverter I 74 to become the potential of the second fuse bar signal (fu 2 — b). The first fuse bar signal (fu 0 — b) of the LOW state and the second fuse bar signal (fu 1 — b) of the HIGH state are inputted to the first NAND gate 71 . The first NAND gate 71 then performs a NAND operation for the two signals (fu 0 — b and fu 1 — b) to output a signal of a HIGH state. The output signal of the first NAND gate 71 keeping the HIGH state is inverted to the LOW state through the fifth inverter I 75 to become the third output signal (out 2 ). The first fuse bar signal (fu 0 — b) of the LOW state and the second fuse signal (fu 1 ) of the LOW state are inputted to the second NAND gate 72 . The second NAND gate 72 performs a NAND operation for the two signals (fu 0 — b and fu 1 ) to output a signal of a HIGH state. The output signal of the second NAND gate 72 keeping the HIGH state is inverted to a LOW state through the sixth inverter I 76 to become the first output signal (out 0 ). The first fuse signal (fu 0 ) of the HIGH state and the second fuse bar signal (fu 1 — b) of the HIGH state are inputted to the third NAND gate 73 . The third NAND gate 73 performs a NAND operation for the two signals (fu 0 and fu 1 — b) to output a signal of a LOW state. The output signal of the third NAND gate 73 keeping the LOW state is inverted to a HIGH state through the seventh inverter I 77 to become the fourth output signal (out 3 ). The first fuse signal (fu 0 ) of the LOW state and the second fuse signal (fu 1 ) of the LOW state are inputted to the fourth NAND gate 74 . The fourth NAND gate 74 performs a NAND operation for the two signals (fu 0 and fu 1 ) to output a signal of a HIGH state. The output signal of the fourth NAND gate 74 keeping the HIGH state is inverted to a LOW state through the eighth inverter I 78 to become a second output signal (out 1 ). As described above, according to the present invention, the width of variation in temperature that can be detected by a temperature detecting circuit using a plurality of detectors. The state of the plurality of the detectors can be detected using the encoder from the outside. Fuse trimming information is transferred from the outside to the detector though the select means to select one of the detectors that can detect correct temperature information. Therefore, the present invention has new effects that it can implement a correct temperature detecting circuit since trimming is possible depending on variation in process or voltage and it can significantly reduce consumption of the standby current since the refresh period can be differentiated depending on each temperature. Although the present invention has been described in connection with the embodiment of the present invention illustrated in the accompanying drawings, it is not limited thereto. It will be apparent to those skilled in the art that various substitutions, modifications and changes may be made thereto without departing from the scope and spirit of the invention.
A temperature detecting circuit includes a first delay unit for outputting a reference signal, a second delay unit for outputting a plurality of delay signals, a detecting unit for outputting a plurality of detecting signals according to the reference signal and delay signals, an encoder for encoding the plurality of the detecting signals, a buffer for outputting the output signal of the encoder to the outside and a fuse information from the outside to a select means, and the select unit that can be programmed according to the fuse information, for outputting a plurality of output signals to the detecting means according to a program state.
Briefly summarize the main idea's components and working principles as described in the context.
[ "BACKGROUND 1.", "Field of the Invention The present invention relates to a temperature detecting circuit and, more particularly, to a temperature detecting circuit that can be exactly implemented since trimming is possible depending on variation in process or voltage and that can significantly reduce consumption of the standby current since the refresh period is differentiated depending on temperature, in such a manner that the width of variation in temperature that can be detected by the temperature detecting circuit can be widened using a plurality of detectors, the status of the plurality of the detectors can be detected at the outside by an encoder, and one of the detectors that can detect correct temperature information by transferring fuse trimming information from the outside to the detecting means via the select means.", "Discussion of Related Art In semiconductor devices, if a device requiring a periodical refresh so as to keep data is needed, a large amount of standby current is necessary for a self-refresh.", "The refresh period that is actually required, however, very differs depending on temperature.", "If temperature is detected and the refresh period is varied depending on temperature, the standby current can be significantly reduced.", "The exactness of a common temperature detecting circuit, however, is lowered depending on variation in external conditions such as process, voltage, and the like.", "FIG. 1 is a block diagram illustrating the construction of a conventional temperature detecting circuit.", "A first delay means 11 receives an input signal (IN) as an input to output a reference signal (ref) depending on temperature that will be detected without being influenced by variation in operating environments such as change in process, voltage, temperature, etc.", "A second delay means 12 outputs a delay signal (tem) whose delay value is changed depending on variation in temperature.", "A detector 13 receives the reference signal (ref) from the first delay means 11 and the delay signal (tem) from the second delay means 12 , as an input and then outputs (dout) a detecting signal (det) indicating whether the delay signal (tem) is lower or higher the reference signal (ref) to the outside through a DQ buffer 14 .", "As such, the detection width of temperature is controlled by correcting the delay width of the first delay means 11 or the second delay means 12 using the data outputted via the DQ buffer 14 .", "In the conventional temperature detecting circuit constructed above, however, since only one detector is employed, the width of variation in temperature that can be detected depending on variation in process or voltage is limited.", "Therefore, if the width of variation in temperature that can be actually detected by a device is large, the device fails to serve as the temperature detecting circuit.", "SUMMARY OF THE INVENTION The present invention is contrived to solve the aforementioned problems.", "The present invention is directed to provide a temperature detecting circuit that can widely control the width of variation in temperature depending on variation in process or voltage by use of a plurality of detectors.", "According to a preferred embodiment of the present invention, there is provided a temperature detecting circuit wherein the state of a plurality of detectors can be detected externally using an encoder.", "Further, the present invention is to provide a temperature detecting circuit that can select a detector capable of detecting correct temperature information by allowing fuse trimming information to be transferred via a select means so that correct temperature information can be transferred to a device from the outside.", "According to a preferred embodiment of the present invention, there is provided A temperature detecting circuit, comprising: a first delay means for outputting a reference signal that is delayed by some time according to an input signal without being affected by variation in temperature;", "a second delay means for delaying the input signal in different delay time according to variation in temperature to generate a plurality of delay signals;", "a detecting means for comparing the reference signal and the plurality of the delay signals, respectively, to output a plurality of detecting signals;", "an encoder for encoding the plurality of the detecting signals into given numbers of output signals;", "a buffer for outputting the output signal of the encoder to the outside and receiving a control signal from the outside as an input;", "and a select means that can be programmed according to the control signal, for selecting one of the detecting signals according to a program state.", "One aspect of the present invention is to provide a temperature detecting circuit, comprising: a first delay means for outputting a reference signal that is delayed by some time according to an input signal without being affected by variation in temperature;", "a second delay means for delaying the input signal in different delay time according to variation in temperature to generate a plurality of delay signals;", "a detecting means having a plurality of detectors, wherein the detector compares the reference signal and the plurality of the delay signals, respectively, to output a plurality of detecting signals;", "an encoder for encoding the plurality of the detecting signals into given numbers of output signals;", "a buffer for outputting the output signal of the encoder to the outside and receiving a control signal from the outside as an input;", "and a select means having a plurality of fuses that can be cut, for cutting the fuses according to the control signal and selecting one of the plurality of the detectors according to the fuse signal depending on the state of the fuse.", "BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which: FIG. 1 is a block diagram illustrating the construction of a conventional temperature detecting circuit;", "FIG. 2 is a block diagram illustrating the construction of a temperature detecting circuit according to the present invention;", "FIG. 3 is a block diagram illustrating the detailed construction of the second delay means shown in FIG. 2 according to an embodiment of the present invention;", "FIG. 4 is a block diagram illustrating the detailed construction of the detecting means shown in FIG. 2 according to an embodiment of the present invention;", "FIG. 5 is a block diagram illustrating the detailed construction of the detector shown in FIG. 4 according to an embodiment of the present invention;", "FIG. 6 is a block diagram illustrating the detailed construction the encoder shown in FIG. 2 according to an embodiment of the present invention;", "and FIGS. 7A and 7B are block diagrams illustrating the detailed construction of the select means shown in FIG. 2 according to an embodiment of the present invention.", "DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention will now be described in detail in connection with preferred embodiments with reference to the accompanying drawings, in which like reference numerals are used to identify the same or similar parts.", "FIG. 2 is a block diagram illustrating the construction of a temperature detecting circuit according to the present invention.", "A first delay means 21 outputs a reference signal (ref) that is delayed by some time according to an input signal (IN) without being affected by variation in operating environments such as variation in temperature, etc.", "The reference signal (ref) is fixed to temperature to be detected and becomes a signal indicating that temperature.", "A second delay means 22 changes the value of the input signal (IN) that is delayed according to on variation in temperature.", "The second delay means 22 outputs a delay signal corresponding temperature to be detected and a plurality of delay signals (tem) corresponding to temperature for which a sufficient margin is taken into consideration on the basis of that temperature to be detected.", "A detecting means 23 consists of a plurality of detectors.", "Each of the detectors uses the reference signal (ref) inputted from the first delay means 21 and the plurality of the delay signals (tem) inputted from the second delay means 22 to detect whether the delay signal (tem) is higher or lower than the reference signal (ref), and then outputs a detecting signal (det).", "The detecting signal (det) outputted from the detecting means 23 has temperature information that is currently being measured in a device.", "In order to output such temperature information to the outside, the encoder 24 encodes temperature information to output a plurality of output signals (dout).", "The plurality of the output signals (dout) outputted by the encoder 24 are provided as information to the outside through a DQ buffer 26 .", "It is confirmed whether such information matches external environments.", "At this time, if actual temperature and temperature that is being recognized in the device are different, fuse information (Fuse Info) is provide to a select means 25 so that the detecting means 23 within the device that actually recognizes external temperature can be selected.", "The select means 25 may have a programmable fuse.", "The select means 25 cuts the fuse depending on fuse information (Fuse Info), combines signals depending on the result to produce information for allowing the means 25 to select one detector that must be used by the device, and then transfers such information to the detecting means 23 .", "Based on information thus transferred, only one of the plurality of the detectors in the detecting means 23 is enabled and remaining detectors are disabled.", "Only the signal detected in the selected detector is thus outputted through the encoder 24 and the DQ buffer 26 .", "FIG. 3 is a block diagram illustrating the detailed construction of the second delay means shown in FIG. 2 according to an embodiment of the present invention.", "An inverter chain 31 delays the input signal (IN) by some time to output a first delay signal (tem 0 ).", "The first delay signal (tem 0 ) is delayed through first and second inverters I 31 and I 32 to become a second delay signal (tem 1 ).", "The second delay signal (tem 1 ) is delayed through third and fourth inverters I 33 and I 34 to become a third delay signal (tem 2 ).", "The third delay signal (tem 2 ) is delayed through fifth and sixth inverters I 35 and I 36 to become a fourth delay signal (tem 3 ).", "In the above, the delay value is extended to some degree depending on a given difference in temperature, by means of the first and second inverters I 31 and I 32 , the third and fourth inverters I 33 and I 34 , and the fifth and sixth inverters I 35 and I 36 .", "It is thus possible to identify the difference in temperature.", "FIG. 4 is a block diagram illustrating the detailed construction of the detecting means 23 shown in FIG. 2 according to an embodiment of the present invention.", "A first detector 41 uses the first delay signal (tem 0 ) outputted from the second delay means and the reference signal (ref) outputted from the first delay means to output a first detecting signal (det 0 ).", "A second detector 42 uses the second delay signal (tem 1 ) outputted from the second delay means and the reference signal (ref) outputted from the first delay means to output a second detecting signal (det 1 ).", "A third detector 43 uses the third delay signal (tem 2 ) outputted from the second delay means and the reference signal (ref) outputted from the first delay means to output a third detecting signal (det 2 ).", "A fourth detector 44 uses the fourth delay signal (tem 3 ) outputted from the second delay means and the reference signal (ref) outputted from the first delay means to output a fourth detecting signal (det 3 ).", "A first transfer gate T 41 outputs the first detecting signal (det 0 ) as the final detecting signal (last — det) according to the first output signal (out 0 ) of the encoder and its inverse signal (outb 0 ).", "A second transfer gate T 42 outputs the second detecting signal (det 1 ) as the final detecting signal (last — det) according to the second output signal (out 1 ) of the encoder and its inverse signal (outb 1 ).", "A third transfer gate T 43 outputs the third detecting signal (det 2 ) as the final detecting signal (last — det) according to the third output signal (out 2 ) of the encoder and its inverse signal (outb 2 ).", "A fourth transfer gate T 44 outputs the fourth detecting signal (det 3 ) as the final detecting signal (det) according to the fourth output signal (out 3 ) of the encoder and its inverse signal (outb 3 ).", "In the detecting means constructed above, at the initial stage, the first to fourth output signals (out 0 to out 3 ) are encoded by the encoder 24 and are then outputted to the outside by the DQ buffer 26 .", "However, only one of the first to fourth transfer gates T 41 to T 44 is turned on according to the output signal of the select means 25 by fuse information (Fuse Info) externally inputted, and only one of the detecting signals (det 0 to det 3 ) of the first to fourth detectors 41 to 44 is outputted to the outside.", "FIG. 5 is a block diagram illustrating the detailed construction of the detector shown in FIG. 4 according to an embodiment of the present invention.", "A first NAND gate 51 performs a NAND operation for an input signal (in) and the output signal of a second NAND gate 52 .", "A second NAND gate 52 performs a NAND operation for the reference signal (ref) and the output signal of the first NAND gate 51 .", "In the above, the input signal (in) is one of the first to fourth delay signals outputted from the second delay means and the reference signal (ref) is a signal inputted from the first delay means.", "The first transfer gate T 51 is driven according to a control signal (act) and its inverse signal (actb) to transfer the output signal of the first NAND gate 51 .", "Further, a latch 53 having first and second inverters I 51 and I 52 latches the output signal of the first NAND gate 51 that is transferred via the first transfer gate T 51 .", "A third inverter I 53 inverts the data that was latched by the latch 53 to output an inverse signal, which is a detecting signal (det).", "FIG. 6 is a block diagram illustrating the detailed construction the encoder 24 shown in FIG. 2 according to an embodiment of the present invention.", "A first inverter I 61 inverts the second detecting signal (det 2 ) outputted from the second detector of the detecting means to produce a first output signal (dout 0 ).", "A first NAND gate 61 performs a NAND operation for the output signal of the first inverter I 61 and the first detecting signal (det 1 ) outputted from the first detector of the detecting means.", "A second NAND gate 62 performs a NAND operation for the second detecting signal (det 2 ) and the third detecting signal (det 3 ) outputted from the third detector of the detecting means.", "A NOR gate 63 performs a NOR operation for the output signals of the first NAND gate 61 and the second NAND gate 62 to output a second output signal (dout 1 ).", "FIG. 7A and 7B are block diagrams illustrating the detailed construction of the select means 25 shown in FIG. 2 according to an embodiment of the present invention, wherein FIG. 7A is a circuit diagram illustrating a fuse signal generating means and FIG. 7B is a circuit diagram illustrating a select signal generating means.", "Referring to FIG. 7A , a first fuse F 71 is connected between the power supply terminal (Vcore) and a first node Q 71 .", "A first NMOS transistor N 71 ) driven by an enable signal (enable) and a second NMOS transistor N 72 driven by the potential of a second node Q 72 are connected in parallel between the first node Q 71 and the ground terminal (Vss).", "A first inverter I 71 inverts the potential of the first node Q 71 to decide the potential of the second node Q 72 .", "The potential of the second node Q 72 becomes a first fuse signal (fu 0 ).", "Furthermore, the potential of the second node Q 72 is inverted through the second inverter I 72 and is then outputted as a first fuse bar signal (fu 0 — b).", "Meanwhile, a second fuse F 72 is connected between the power supply terminal (Vcore) and a third node Q 73 .", "A third NMOS transistor N 73 driven by the enable signal (enable) and a fourth NMOS transistor N 74 driven by the potential of a fourth node Q 74 are connected in parallel between the third node Q 73 and the ground terminal (Vss).", "A third inverter I 73 inverts the potential of the third node Q 73 to decide the potential of the fourth node Q 74 and the potential of the fourth node Q 74 becomes a second fuse signal (fu 1 ).", "Furthermore, the potential of the fourth node Q 74 is inverted through the fourth inverter I 74 and is then outputted as a second fuse bar signal (fu 1 — b).", "By reference to FIG. 7B , a first NAND gate 71 performs a NAND operation for the first fuse bar signal (fu 0 — b) and the second fuse bar signal (fu 1 — b) and a fifth inverter I 75 inverts the output signal of the first NAND gate 71 to output a third output signal (out 2 ).", "A second NAND gate 72 performs a NAND operation for the first fuse bar signal (fu 0 — b) and the second fuse signal (fu 1 ) and a sixth inverter I 76 inverts the output signal of the second NAND gate 72 to output a first output signal (out 0 ).", "A third NAND gate 73 performs a NAND operation for the first fuse signal (fu 0 ) and the second fuse bar signal (fu 1 — b) and a seventh inverter I 77 inverts the output signal of the third NAND gate 73 to output a fourth output signal (out 3 ).", "Furthermore, a fourth NAND gate 74 performs a NAND operation for the first fuse signal (fu 0 ) and the second fuse signal (fu 1 ) and an eighth inverter I 78 inverts the output signal of the fourth NAND gate 74 to output a second output signal (out 1 ).", "The select means constructed above selectively cuts the first and second fuses F 71 and F 72 according to fuse information (Fuse Info) and, according to its result, selects one of the plurality of the detectors 31 to 34 constituting the detecting means 23 .", "The operation when only the fuse F 71 is cut according to fuse information (Fuse Info) will now be described by way of an example.", "If the first NMOS transistor N 71 is turned on by the enable signal (enable), the first node Q 71 keeps a LOW state since the first fuse F 71 is cut.", "The potential of the first node Q 71 keeping the LOW state is inverted to a HIGH state through the first inverter I 71 and the potential of the second node Q 72 keeping the HIGH state becomes the potential of the first fuse signal (fu 0 ).", "Further, the second NMOS transistor N 72 is turned on by the potential of the second node Q 72 and the potential of the second node Q 72 is inverted to a LOW state through the second inverter I 72 to become the potential of the first fuse bar signal (fu 0 — b).", "Meanwhile, if the third NMOS transistor N 73 is turned on by the enable signal (enable), the third node Q 73 keeps a HIGH state since the second fuse F 72 keeps a normal state.", "The potential of the third node Q 73 keeping the HIGH state is inverted to a LOW state through the third inverter I 73 and the potential of the fourth node Q 74 keeping the LOW state becomes the potential of the second fuse signal (fu 1 ).", "Furthermore, the fourth NMOS transistor N 74 is turned off by the potential of the fourth node Q 74 and the potential of the fourth node Q 74 is inverted to a HIGH state through the fourth inverter I 74 to become the potential of the second fuse bar signal (fu 2 — b).", "The first fuse bar signal (fu 0 — b) of the LOW state and the second fuse bar signal (fu 1 — b) of the HIGH state are inputted to the first NAND gate 71 .", "The first NAND gate 71 then performs a NAND operation for the two signals (fu 0 — b and fu 1 — b) to output a signal of a HIGH state.", "The output signal of the first NAND gate 71 keeping the HIGH state is inverted to the LOW state through the fifth inverter I 75 to become the third output signal (out 2 ).", "The first fuse bar signal (fu 0 — b) of the LOW state and the second fuse signal (fu 1 ) of the LOW state are inputted to the second NAND gate 72 .", "The second NAND gate 72 performs a NAND operation for the two signals (fu 0 — b and fu 1 ) to output a signal of a HIGH state.", "The output signal of the second NAND gate 72 keeping the HIGH state is inverted to a LOW state through the sixth inverter I 76 to become the first output signal (out 0 ).", "The first fuse signal (fu 0 ) of the HIGH state and the second fuse bar signal (fu 1 — b) of the HIGH state are inputted to the third NAND gate 73 .", "The third NAND gate 73 performs a NAND operation for the two signals (fu 0 and fu 1 — b) to output a signal of a LOW state.", "The output signal of the third NAND gate 73 keeping the LOW state is inverted to a HIGH state through the seventh inverter I 77 to become the fourth output signal (out 3 ).", "The first fuse signal (fu 0 ) of the LOW state and the second fuse signal (fu 1 ) of the LOW state are inputted to the fourth NAND gate 74 .", "The fourth NAND gate 74 performs a NAND operation for the two signals (fu 0 and fu 1 ) to output a signal of a HIGH state.", "The output signal of the fourth NAND gate 74 keeping the HIGH state is inverted to a LOW state through the eighth inverter I 78 to become a second output signal (out 1 ).", "As described above, according to the present invention, the width of variation in temperature that can be detected by a temperature detecting circuit using a plurality of detectors.", "The state of the plurality of the detectors can be detected using the encoder from the outside.", "Fuse trimming information is transferred from the outside to the detector though the select means to select one of the detectors that can detect correct temperature information.", "Therefore, the present invention has new effects that it can implement a correct temperature detecting circuit since trimming is possible depending on variation in process or voltage and it can significantly reduce consumption of the standby current since the refresh period can be differentiated depending on each temperature.", "Although the present invention has been described in connection with the embodiment of the present invention illustrated in the accompanying drawings, it is not limited thereto.", "It will be apparent to those skilled in the art that various substitutions, modifications and changes may be made thereto without departing from the scope and spirit of the invention." ]
CROSS-REFERENCE TO RELATED CASE This application is a continuation application of my commonly assigned, co-pending U.S. Application Ser. No. 483,076, filed June 25, 1974, now abondoned, and entitled "Arangement For Maintaining Optimum Minimum Operating Clearance Between Rotor And Stator Components Of Turbo-Machines, Compressors, Pressure Wave Machines And The Like." BACKGROUND OF THE INVENTION The present invention relates to an improved technique by means of which the necessary operating clearance between the rotor of a machine and its associated stator component can be maintained at a safe minimum thereby to maintain an optimum efficiency of operation during the life of the machine. The invention is applicable to various types of machines incorporating rotor and stator components such as for example various types of turbines, compressors and pressure wave machines, an example of the latter being disclosed in U.S. Pat. No. 3,591,313, granted July 6, 1971 to Alfred Wunsch. The efficiency of such machines is determined by various factors including the size of the operating clearance between the rotor and stator and will decrease as the clearance increases. For this reason, efforts are being continuously made to reduce the clearance as much as possible without, however, incurring potential damage to the machinery as would be caused by accidental touching of the stator by the rotor. The optimum amount of the necessary operating clearance is determined on the basis of the properties of the materials involved, manufacturing technology, the size of the rotor and stator and also the operating conditions of the machine. Care must also be taken that in exceptional circumstances, whenever the rotor touches the stator, that damage will not occur. Such exceptional circumstances may arise, for example, during the starting-up period of the machine, or in the event of strong vibrations occurring during operation, or excessive increases in machine temperature and the like. It has been proposed, for example, in the case of turbo-machines and compressors, to provide the tips of the rotor blading with a bevelled surface in order to keep the operating clearance between the blading and the surrounding surface of the stator to a minimum. In the event that the tips of the blades touch the stator surface, the bevelled blade will deform, or wear down, and no harmful forces will be generated. It has also been proposed, in order to establish a minimum clearance, to coat the walls of the stator at their inner surface opposite the rotor with a relatively soft layer which can be abraded away or deformed by any accidental touching of the tips of the rotor blading. Such soft layers can consist, for example, of graphite, die-cast or sintered porous nickel-chromium alloys, or nickel-graphite materials, honeycombed cells, etc. and are called abrasable layers for touch protection. All protective layers of this type are lacking in the property to "grow" i.e. to increase in size, under the influence of the environmental temperature and/or the particular atmosphere in which the machine operates. These know expedients have the disadvantage that the bevelled blade ends or soft layers will change their shape irreversibly upon contact, either by deforming or wearing down. In addition thereto, the blade ends, in the case of turbo-machines and compressors, or the ends of the cell walls, in the case of pressure wave machines, as well as the stator will be subjected to corrosion and erosion, with the result that the operating clearance as between rotor and stator will increase continuously and the efficiency of the machine will decrease in a corresponding manner. SUMMARY OF THE INVENTION The principal object of the present invention is to maintain the operating clearance between the rotor and stator at a safe minimum even in the case of operations lasting for long periods of time. This objective is attained in that within the region of the clearance, there is utilized an abradable material that will "grow," i.e. increase in size and which is brought about by the operating temperature and/or working atmosphere of the machine. BRIEF DESCRIPTION OF THE DRAWINGS The inventive concepts will be further explained in further detail as applied to different types of machines and as illustrated in the accompanying drawings wherein: FIG. 1 is a sectional view showing a portion of the rotor and stator of a compressor as improved by the invention; FIG. 2 is a sectional view of a portion of the rotor and stator of a pressure wave machine; FIG. 3 are graphs plotting the "growth" characteristic of two different abradable sintered graphite-metal alloys that can be used in establishing the region of clearance as between rotor and stator components of a machine; FIG. 4 are also graphs plotting the "growth" of three different types of abradable gray iron alloys that can be used in establishing the clearance region; and FIG. 5 is a sectional view of a portion of the rotor and stator components of another pressure wave machine. DETAILED DESCRIPTION OF THE INVENTION With reference now to FIG. 1, which shows a section of an axial cut through a compressor, there is provided the stator component 1, the rotor 2 and the rotor blading 3. The stator and rotor are made of a volume-stable material, for example, steel. In order to maintain the distance 4 between the ends of the rotor blading 3 and the stator 1 as small as possible, there is secured at the internal surface of the stator 1 opposite the blade ends a segmented ring 5 and which is made from one of the abradable materials heretofore referred to as being capable of "growing," preferably gray cast iron. In the event that the tips of the blades 3 touch the segmental ring 5, they will become deformed if they are bevelled, or the segmental ring 5, if soft will become eroded on the rotor side. Due to, for example, the oxidizing atmosphere in which the compressor works on the one hand, and the operating temperature of the compressor on the other hand, or both, the ring 5 will irreversibly "grow" in the radial direction towards the rotor axis thus reducing the clearance 6 that has been accidently caused to increase by the unforseen touching and corrosion-erosion effect heretofore referred to. In this manner, there is compensated out the corrosion- and erosion-degradation, as well as the wear caused by unforseen vibrations and temperature increases. Thus the segmental ring 5 by its growth serves as a self-compensating member to maintain the operating clearance at an optimum minimum thereby achieving a continuous optimum efficiency over a long period of operating time of the machine. In FIG. 2, the teachings of the invention have been illustrated as applied to a pressure wave machine of the general type more completely disclosed, for example, in the above-referred to U.S. Pat. No. 3,591,313. The stator component 7 of the machine is made from cast iron with spheroidal graphite and its rotor 8 is made from a nickel alloy. In order to maintain the distance 9 between the front end of the celled rotor 8 and the stator 7 as small as possible a plate 12 is cast into the stator 7 so as to face the end of the rotor. Plate 12 is made from an abradable material capable of growth, preferably soft gray iron. Thus, here again, the plate 12 will "grow," i.e. increase its volume in the axial direction towards the end of rotor 8 as a result of an oxidizing working atmosphere handled by the machine, on the one hand and/or by the operating temperature of the machine, on the other hand. Thus, the clearance 10 will be maintained at an optimum minimum value. The embodiment illustrated in FIG. 2 can be modified by securing plate 12 to the front end of rotor 8 rather than to the stator so that plate 12 will "grow" in the direction of the rotor axis towards stator 7, thereby achieving the same result. In principle, it is thus feasible to affix such a self-compensating growth or growable component to the rotor and/or the stator. Since the rotor parts are usually subjected to heavy mechanical stresses it will be expedient to provide only the stator component with the necessary growable element. If, in the embodiments illustrated in FIGS. 1 and 2, no unexpected circumstances arise and no wear occurs, so that the growth of the segmented ring 5, or of plate 12, respectively will become greater than the abrasive wear-down effect caused by corrosion and erosion, the parts will be worn down gradually by the rotor, with the result that the clearance 6, as in FIG. 1, or clearance 10 as in FIG. 2, will always be maintained at a minimum. The growth characteristics of three different types of gray cast iron are plotted in FIG. 4, in relation to annealing time in hours at an air temperature of 650° C. Plot "a" is for a gray cast iron containing 3.7% carbon, 2.6% silicon, (78HB). Plot "b" is for a gray cast iron containing 3.3% carbon, 5.9% silicon, (131HB). Plot "c" is for a gray cast iron containing 3.3% carbon, 6.5% silicon, (149HB). The "growth" characteristic of the gray cast iron which is utilized for the manufacture of the segmented ring 5 or plate 12, can be varied widely, for example, by proper selection of its components, by variation of the cooling speed during casting of the iron, by thermal treatment of the iron after casting, and so forth. Furthermore, the growth of the segmented ring 5 or plate 12 produced from gray cast iron is influenced by its shape, the type of fastening to the base material, by its stress, and by the operating temperature and type of atmosphere in which the machine operates. It is also possible to use for the manufacture of the segmented ring 5 and plate 12 abradable cast iron types other than gray cast iron, such as malleable cast iron, cast iron with graphite, partially, in globular and partially in lamellar form, and so forth, dependent upon the characteristics desired for the growable element. The growable elements are secured to the supporting base material of the stator or of the rotor by standard methods, mechanically, or by soldering, welding, casting, sintering and so forth. The growable elements also can be made from abradable materials other than cast iron, i.e. materials which will grow by oxidation at higher temperatures. Particularly suitable are sintered graphite-metal-materials, their metal phase containing nickel, copper, iron, tin, lead, antimony and/or zinc. The two different graphs plotted in FIG. 3 in which growth is plotted in relation to annealing time in hours in air at a temperature of 350° C show that the growth will be faster if the metal phase contains a greater amount of readily oxidizable components such as copper and tin. Plot "a" is for a sintered material containing, by weight, 8% carbon, 55% copper, 28% nickel and 9% iron. Plot "b" is for a sintered material containing, by weight, 8% carbon, 78% copper, 12% tin and 2% nickel. In principle, it is possible to use for the manufacture of the elements 5 and 12 any abradable material that will "grow" under the influence of chemical elements, or in combination with the environment, for example, by carburization, nitriding, sulphurating, oxidation and the like, or by a change in structure under the influence of the operating temperature. If it is desired to keep the forces generated by touching of the rotor and stator parts to a very low value, it is possible, in the case of the two different embodiments of the invention which have been described herein, to apply to the rotor side of the growable elements 5 or 12 respectively, an additional, known soft protective layer as previously described which will abrade off with ease. The embodiment of the invention as illustrated in FIG. 5 is similar to that of FIG. 2, namely a pressure wave machine and hence the same numerals have been used to designate those parts which are common to both. The construction according to FIG. 5 differs from that of FIG. 2 in that the front end cover plate 11 of the stator 7' and plate 12' have been integrated into a single structure and which is made from a material, preferably gray cast iron, which will grow under the influence of the particular atmosphere or temperature at which the pressure wave machine operates. A "separation" as between the cover plate portion 11 and plate 12' is shown symbolically by a dash-dot line. Any growth of the cover plate portion can be prevented, for example, by locating cooling coils 13 within this portion, thus assuring a continuous low operating temperature thereof. Here again, it is possible to place on one, or both of the front sides S2,S1 of the plate portion 12' and the end of the rotor 8', respectively, protective layers, as described, which will abrade off with ease. While there are shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited hereto, but may be otherwise variously embodied and practiced within the scope of the following claims.
Between the rotor and stator components of turbomachines, compressors, pressure wave machines and the like, the clearance space is partially filled out by an abradable element which is capable of "growing" when subjected to an elevated temperature and/or to the influence of the particular atmosphere in which the machine operates. As the element grows, it compensates for corrosion and erosion factors which take place in the machine and which otherwise tend to increase the clearance. Suitable materials which will "grow" under these operating conditions are gray cast iron and a sintered graphite-metal.
Provide a concise summary of the essential information conveyed in the context.
[ "CROSS-REFERENCE TO RELATED CASE This application is a continuation application of my commonly assigned, co-pending U.S. Application Ser.", "No. 483,076, filed June 25, 1974, now abondoned, and entitled "Arangement For Maintaining Optimum Minimum Operating Clearance Between Rotor And Stator Components Of Turbo-Machines, Compressors, Pressure Wave Machines And The Like.", """, "BACKGROUND OF THE INVENTION The present invention relates to an improved technique by means of which the necessary operating clearance between the rotor of a machine and its associated stator component can be maintained at a safe minimum thereby to maintain an optimum efficiency of operation during the life of the machine.", "The invention is applicable to various types of machines incorporating rotor and stator components such as for example various types of turbines, compressors and pressure wave machines, an example of the latter being disclosed in U.S. Pat. No. 3,591,313, granted July 6, 1971 to Alfred Wunsch.", "The efficiency of such machines is determined by various factors including the size of the operating clearance between the rotor and stator and will decrease as the clearance increases.", "For this reason, efforts are being continuously made to reduce the clearance as much as possible without, however, incurring potential damage to the machinery as would be caused by accidental touching of the stator by the rotor.", "The optimum amount of the necessary operating clearance is determined on the basis of the properties of the materials involved, manufacturing technology, the size of the rotor and stator and also the operating conditions of the machine.", "Care must also be taken that in exceptional circumstances, whenever the rotor touches the stator, that damage will not occur.", "Such exceptional circumstances may arise, for example, during the starting-up period of the machine, or in the event of strong vibrations occurring during operation, or excessive increases in machine temperature and the like.", "It has been proposed, for example, in the case of turbo-machines and compressors, to provide the tips of the rotor blading with a bevelled surface in order to keep the operating clearance between the blading and the surrounding surface of the stator to a minimum.", "In the event that the tips of the blades touch the stator surface, the bevelled blade will deform, or wear down, and no harmful forces will be generated.", "It has also been proposed, in order to establish a minimum clearance, to coat the walls of the stator at their inner surface opposite the rotor with a relatively soft layer which can be abraded away or deformed by any accidental touching of the tips of the rotor blading.", "Such soft layers can consist, for example, of graphite, die-cast or sintered porous nickel-chromium alloys, or nickel-graphite materials, honeycombed cells, etc.", "and are called abrasable layers for touch protection.", "All protective layers of this type are lacking in the property to "grow"", "i.e. to increase in size, under the influence of the environmental temperature and/or the particular atmosphere in which the machine operates.", "These know expedients have the disadvantage that the bevelled blade ends or soft layers will change their shape irreversibly upon contact, either by deforming or wearing down.", "In addition thereto, the blade ends, in the case of turbo-machines and compressors, or the ends of the cell walls, in the case of pressure wave machines, as well as the stator will be subjected to corrosion and erosion, with the result that the operating clearance as between rotor and stator will increase continuously and the efficiency of the machine will decrease in a corresponding manner.", "SUMMARY OF THE INVENTION The principal object of the present invention is to maintain the operating clearance between the rotor and stator at a safe minimum even in the case of operations lasting for long periods of time.", "This objective is attained in that within the region of the clearance, there is utilized an abradable material that will "grow,"", "i.e. increase in size and which is brought about by the operating temperature and/or working atmosphere of the machine.", "BRIEF DESCRIPTION OF THE DRAWINGS The inventive concepts will be further explained in further detail as applied to different types of machines and as illustrated in the accompanying drawings wherein: FIG. 1 is a sectional view showing a portion of the rotor and stator of a compressor as improved by the invention;", "FIG. 2 is a sectional view of a portion of the rotor and stator of a pressure wave machine;", "FIG. 3 are graphs plotting the "growth"", "characteristic of two different abradable sintered graphite-metal alloys that can be used in establishing the region of clearance as between rotor and stator components of a machine;", "FIG. 4 are also graphs plotting the "growth"", "of three different types of abradable gray iron alloys that can be used in establishing the clearance region;", "and FIG. 5 is a sectional view of a portion of the rotor and stator components of another pressure wave machine.", "DETAILED DESCRIPTION OF THE INVENTION With reference now to FIG. 1, which shows a section of an axial cut through a compressor, there is provided the stator component 1, the rotor 2 and the rotor blading 3.", "The stator and rotor are made of a volume-stable material, for example, steel.", "In order to maintain the distance 4 between the ends of the rotor blading 3 and the stator 1 as small as possible, there is secured at the internal surface of the stator 1 opposite the blade ends a segmented ring 5 and which is made from one of the abradable materials heretofore referred to as being capable of "growing,"", "preferably gray cast iron.", "In the event that the tips of the blades 3 touch the segmental ring 5, they will become deformed if they are bevelled, or the segmental ring 5, if soft will become eroded on the rotor side.", "Due to, for example, the oxidizing atmosphere in which the compressor works on the one hand, and the operating temperature of the compressor on the other hand, or both, the ring 5 will irreversibly "grow"", "in the radial direction towards the rotor axis thus reducing the clearance 6 that has been accidently caused to increase by the unforseen touching and corrosion-erosion effect heretofore referred to.", "In this manner, there is compensated out the corrosion- and erosion-degradation, as well as the wear caused by unforseen vibrations and temperature increases.", "Thus the segmental ring 5 by its growth serves as a self-compensating member to maintain the operating clearance at an optimum minimum thereby achieving a continuous optimum efficiency over a long period of operating time of the machine.", "In FIG. 2, the teachings of the invention have been illustrated as applied to a pressure wave machine of the general type more completely disclosed, for example, in the above-referred to U.S. Pat. No. 3,591,313.", "The stator component 7 of the machine is made from cast iron with spheroidal graphite and its rotor 8 is made from a nickel alloy.", "In order to maintain the distance 9 between the front end of the celled rotor 8 and the stator 7 as small as possible a plate 12 is cast into the stator 7 so as to face the end of the rotor.", "Plate 12 is made from an abradable material capable of growth, preferably soft gray iron.", "Thus, here again, the plate 12 will "grow,"", "i.e. increase its volume in the axial direction towards the end of rotor 8 as a result of an oxidizing working atmosphere handled by the machine, on the one hand and/or by the operating temperature of the machine, on the other hand.", "Thus, the clearance 10 will be maintained at an optimum minimum value.", "The embodiment illustrated in FIG. 2 can be modified by securing plate 12 to the front end of rotor 8 rather than to the stator so that plate 12 will "grow"", "in the direction of the rotor axis towards stator 7, thereby achieving the same result.", "In principle, it is thus feasible to affix such a self-compensating growth or growable component to the rotor and/or the stator.", "Since the rotor parts are usually subjected to heavy mechanical stresses it will be expedient to provide only the stator component with the necessary growable element.", "If, in the embodiments illustrated in FIGS. 1 and 2, no unexpected circumstances arise and no wear occurs, so that the growth of the segmented ring 5, or of plate 12, respectively will become greater than the abrasive wear-down effect caused by corrosion and erosion, the parts will be worn down gradually by the rotor, with the result that the clearance 6, as in FIG. 1, or clearance 10 as in FIG. 2, will always be maintained at a minimum.", "The growth characteristics of three different types of gray cast iron are plotted in FIG. 4, in relation to annealing time in hours at an air temperature of 650° C. Plot "a"", "is for a gray cast iron containing 3.7% carbon, 2.6% silicon, (78HB).", "Plot "b"", "is for a gray cast iron containing 3.3% carbon, 5.9% silicon, (131HB).", "Plot "c"", "is for a gray cast iron containing 3.3% carbon, 6.5% silicon, (149HB).", "The "growth"", "characteristic of the gray cast iron which is utilized for the manufacture of the segmented ring 5 or plate 12, can be varied widely, for example, by proper selection of its components, by variation of the cooling speed during casting of the iron, by thermal treatment of the iron after casting, and so forth.", "Furthermore, the growth of the segmented ring 5 or plate 12 produced from gray cast iron is influenced by its shape, the type of fastening to the base material, by its stress, and by the operating temperature and type of atmosphere in which the machine operates.", "It is also possible to use for the manufacture of the segmented ring 5 and plate 12 abradable cast iron types other than gray cast iron, such as malleable cast iron, cast iron with graphite, partially, in globular and partially in lamellar form, and so forth, dependent upon the characteristics desired for the growable element.", "The growable elements are secured to the supporting base material of the stator or of the rotor by standard methods, mechanically, or by soldering, welding, casting, sintering and so forth.", "The growable elements also can be made from abradable materials other than cast iron, i.e. materials which will grow by oxidation at higher temperatures.", "Particularly suitable are sintered graphite-metal-materials, their metal phase containing nickel, copper, iron, tin, lead, antimony and/or zinc.", "The two different graphs plotted in FIG. 3 in which growth is plotted in relation to annealing time in hours in air at a temperature of 350° C show that the growth will be faster if the metal phase contains a greater amount of readily oxidizable components such as copper and tin.", "Plot "a"", "is for a sintered material containing, by weight, 8% carbon, 55% copper, 28% nickel and 9% iron.", "Plot "b"", "is for a sintered material containing, by weight, 8% carbon, 78% copper, 12% tin and 2% nickel.", "In principle, it is possible to use for the manufacture of the elements 5 and 12 any abradable material that will "grow"", "under the influence of chemical elements, or in combination with the environment, for example, by carburization, nitriding, sulphurating, oxidation and the like, or by a change in structure under the influence of the operating temperature.", "If it is desired to keep the forces generated by touching of the rotor and stator parts to a very low value, it is possible, in the case of the two different embodiments of the invention which have been described herein, to apply to the rotor side of the growable elements 5 or 12 respectively, an additional, known soft protective layer as previously described which will abrade off with ease.", "The embodiment of the invention as illustrated in FIG. 5 is similar to that of FIG. 2, namely a pressure wave machine and hence the same numerals have been used to designate those parts which are common to both.", "The construction according to FIG. 5 differs from that of FIG. 2 in that the front end cover plate 11 of the stator 7'", "and plate 12'", "have been integrated into a single structure and which is made from a material, preferably gray cast iron, which will grow under the influence of the particular atmosphere or temperature at which the pressure wave machine operates.", "A "separation"", "as between the cover plate portion 11 and plate 12'", "is shown symbolically by a dash-dot line.", "Any growth of the cover plate portion can be prevented, for example, by locating cooling coils 13 within this portion, thus assuring a continuous low operating temperature thereof.", "Here again, it is possible to place on one, or both of the front sides S2,S1 of the plate portion 12'", "and the end of the rotor 8', respectively, protective layers, as described, which will abrade off with ease.", "While there are shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited hereto, but may be otherwise variously embodied and practiced within the scope of the following claims." ]
GOVERNMENT CONTRACT This invention was made with Government support under Contract F33615-86-4526 awarded by the U.S. Air Force. The Government has certain rights in this invention. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to Ion Mobility Spectrometers and more particularly to extending the dynamic range of the ion mobility spectrometer by using an input sample air mixer which is controlled by an electrical signal. 2. Description of the Prior Art Present ion mobility spectrometers have limited dynamic range and are easily saturated when the sample molecules exceed the number of reaction ions available to ionize the sample molecules. Normal sensitivities of ion mobility spectrometers is in the range of parts per billion. An ionizer in the reaction region generates reactant ions over a period of time which in turn are attracted by the affinity of the sample molecule which removes charge from the reactant ions to itself. The ionized sample molecules are then detected by their drift time in a drift region. A typical range of concentrations of the sample is less than 100 to 1. U.S. Pat. No. 4,259,573 which issued on Mar. 31, 1981 to J. M. Prober et al., describes an accurate method of determining small concentrations of chemical compounds by plasma chromotography "Ion Mobility Spectrometry". Small, known increments of species A plus, optionally, another calibrant species are introduced in turn into the plasma chromotograph together with the unknown sample chemical and the respective changes of the amplitude or area of a characteristic ion peak of species A in the unknown sample are measured. U.S. Pat. No. 4,311,669 which issued on Jan. 19, 1982 to G. E. Spangler describes a sample inlet port of an ion mobility detector having a membrane interface. The sample which is included as a vapor component in a gas stream impinges on the exterior surface of the membrane and penetrates the membrane and is carried into the ion mobility spectrometer by means of a carrier gas which scrubs the interior surface of the membrane. U.S. Pat. No. 4,551,624 which issued on Nov. 5, 1985 to G. E. Spangler et al. describes an ion mobility spectrometer system wherein a reagent such as acetone and/or carbon tetrachloride is injected into the carrier gas prior to entering the reaction region. The reagent has a higher proton affinity, electron affinity, or acidity than contaminants in the sample gas, a lower proton affinity, electron affinity, or acidity than at least 1 constituent of the sample gas to be detected, and does not cluster with water disposed in the reagent source. SUMMARY OF THE INVENTION A method and apparatus is described for detecting ions comprising an air mixer having a first input port for receiving clean air and a second input port for receiving sample air, the air mixer having a control input responsive to electrical signals for controlling the mixture of clean air received from the first input port to sample air received from the second input port, the air mixer having an output port coupled to the inlet of a reaction region, the reaction region including an ionization source for generating ions from the mixed clean air and sample air to form reactant ions and sample ions from selected sample molecules in the sample air, a shutter grid for introducing ions from the reaction region into the drift region having an electric field for drifting the ions towards a collector with circuitry attached for measuring the amplitude and mobility of the reaction ions and sample ions in the drift region, the circuitry including means for generating a first electrical signal indicative of the reaction ion amplitude, a second circuit for generating a second electrical signal from the first electrical signal indicative of a desired air mixture of clean air to sample air in response to the amplitude of the first electrical signal, the second electrical signal coupled to the control input of the air mixer, and a third circuit coupled to the first and second electrical signals for generating a third electrical signal indicative of the concentration of the sample molecule in the sample air at the second input port. It is an object of the invention to extend the dynamic range of the ion mobility spectrometer by using at its input an air mixer with the ratio of sample air to clean air varied as a function of a selected output signal from the ion mobility spectrometer. It is a further object of the invention to utilize an input sample air mixer to dilute the sample being measured to prevent the sample from saturating the output of the ion mobility spectrometer. The concentration of the chemical in the sample air that is being measured is then determined by the air mixer ratio and a selected output signal from the ion mobility spectrometer. It is a further object of the invention to generate a feedback signal from the amplitude of the reactant ion output signal for diluting or premixing the input sample prior to entry into the ion mobility spectrometer. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is one embodiment of the invention. FIG. 2 is a graph of a reactant ion peak from an ion mobility spectrometer. FIGS. 3-5 are graphs of the reactant ion peak and the sample ion peak from an ion mobility spectrometer. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, an ion mobility spectrometer for detecting ions such as sample ions from sample air 12. An air mixer 14 has a first input port 16 for receiving clean air 18. Clean air 18 may be air which has been scrubbed to be free of sample molecules or may be a gas such as nitrogen free of sample molecules. A second input port 20 receives sample air 12 which may contain sample molecules of a chemical of unknown concentration. Sample air 12 might be a gas such as nitrogen and the sample molecules. Air mixer 14 may have valves for controlling the flow of clean air 18 and sample air 12 into air mixer 14 which are mixed together therein and vented through output port 22. Air mixer 14 has a control input responsive to electrical signals over lead 24 for controlling the mixture of clean air received from input port 16 and sample air received from input port 20. Air mixer 14 has an output port 22 coupled to the inlet 26 of reaction region 28 of ion mobility spectrometer cell 30. Reaction region 28 includes an ionization source such as a nickle 63 which emits beta particles which ionizes the clean air 18 to provide reaction ions in reaction region 28. The reaction ions in turn ionize sample molecules which have a stronger affinity for the charge on the reaction ions. A shutter grid 34 allows sample ions and reaction ions to pass from reaction region 28 to drift region 36. The ions travel in direction shown by arrow 37 toward collector 38. Reaction region 28 may include means for generating an electric field therein to move the ions towards shutter grid 34. Drift region 36 may include means for generating an electric field therein to move the ions towards collector 38. One example of an ion mobility spectrometer cell 30 is described in U.S. Pat. No. 4,378,499 which issued on Mar. 29, 1983 to G. E. Spangler et al. entitled "Chemical Conversion For Ion Mobility Detectors Using Surface Interactions" which is incorporated herein by reference to show the construction details and operation of an ion mobility spectrometer cell. Drift Gas 40 which may be for example dry nitorgen enters inlet 44 shown by arrow 42 into drift region 36 which exits vent 46 as shown by arrow 48. The clean air 18 and sample air 12 which enters inlet 26 of reaction region 28 is vented by vent 46 shown by arrow 50. The ions in the drift region 36 are collected by collector 38 and are neutralized. The neutralized molecules flow with the drift gas to vent 46. The voltage on collector 38 is carried over lead 52 to an input of circuit 54. Circuit 54 provides a means for measuring the amplitude and drift time of reactant ions and sample ions reaching collector 38. Circuit 54 generates a first electrical signal indicative of the reactant ion amplitude which is coupled over lead 56 to an input of circuit 58. Circuit 58 functions to generate a second electrical signal on lead 24 from the first electrical signal on lead 56 indicative of a desired air mixture in air mixer 14 of clean air to sample air in response to the amplitude of the first electrical signal. The second electrical signal from circuit 58 is coupled over lead 24 to the control input of air mixture 14 and to an input of circuit 60. Circuit 54 also generates a third electrical signal indicative of the sample ion amplitude which is coupled over lead 62 to an input of circuit 60. Circuit 60 functions to generate a fourth electrical signal on lead 64 indicative of the concentration of the sample molecules in sample air 12. Circuit 60 functions to combine mathematically the third electrical signal indicative of amplitude of the sample ion with the second electrical signal indicative of a desired air mixture to provide the fourth electrical signal. In operation of the ion mobility spectrometer 10, first clean air 18 was passed through air mixture 14 into reaction region 28 where reactant ions were generated and measured in drift region 36. FIG. 2 is a graph of the reactant ion peak shown by curve 68. In FIG. 2 the ordinant represents the response in units of current and the abscissa represents time. The electrical signal representative of the reactant ion peak shown by curve 68 would be provided on lead 52 to the input of circuit 58. In clean air using water chemistry, reactant ions form in both positive and negative operating modes. The reactant ions are ionized clusters of water molecules and nitrogen as described by S. H. Kim et al. "Mobility Behavior and Composition of Hydrated Positive Reactant Ions in Plasma Chromotography with Nitrogen Carrier Gas" Anal.Chem.1978,50. For the purposes of providing a test, an organic molecule methyl salicylate also known as oil of wintergreen was used as the sample molecule. Methyl salicylate is a much larger molecule than the reactant ions and has a lower mobility. Clean air 18 and sample air 12 containing methyl salicylate were mixed in air mixer 14 to provide a signature of 0.02 gamma which was passes into reaction region 28 wherein reactant ions were generated which in turn formed sample ions. The reactant ions and the sample ions were measured in drift region 36 and collected by collector 38. FIG. 3 is a graph of the response of the signal on lead 52. Curve 70 shows the reactant ion peak and curve 72 shows the sample ion peak wherein the sample molecule is methyl salicylae. In FIG. 3 the ordinant represents amplitude in units of current and the abscissa represents time. Generally, the number of ions generated in a unit of time in reaction region 28 is constant and therefore a limited number of molecules will become ionized prior to entry into the drift region 36. Thus the reduction of the amplitude peak of the reactant ion shown by curve 70 compared to curve 68 in FIG. 2 is due to the fact that reactant ions lost charge to form sample ions shown by curve 72 in FIG. 3. A further test was run wherein clean air 18 and sample air 12 was mixed in air mixer 14 to provide a concentration of methyl salicylate of 0.04 gamma which was passed into reaction region 28. The reactant ions and sample ions were measured in drift region 36 at collector 38. FIG. 4 shows the response of the electrical signal on lead 52. In FIG. 4 the ordinant represents amplitude in units of current and the abscissa represents time. The reactant ion peak is shown by curve 76 and the sample ion peak is shown by curve 78. It is noted that compared to FIG. 3 the reactant ion peak in FIG. 4 has diminished while the sample ion peak has increased. A further test was run wherein clean air 18 and sample air 12 was mixed in air mixer 14 to provide a concentration of methyl salicylate of 0.06 gamma which was passed into reaction region 28. The reactant ions and sample ions were measured in drift region 36 at collector 38. FIG. 5 shows a graph of the response on lead 52. In FIG. 5 the ordinant represents amplitude in units of current and the abscissa represents time. The reactant ion peak is shown by curve 80 and the sample ion peak is shown by curve 82. As compared to FIG. 4 the reactant ion peak 80 in FIG. 5 has diminished further while the sample ion peak has increased. At this point as shown in FIG. 5, very few reactant ions are left to be used to ionize sample molecules, therefore the ion mobility spectrometer cell 30 is very near saturation. Thus once the reactant ion peak disappears, presumably all reactant ions were used to ionize sample ions and additional sample molecules may be present which were not ionized due to the insufficiency of reactant ions. FIGS. 3 through 5 show that the total ion concentration of reactant ions and sample ions has remained essentially constant. Circuit 58 functions to provide feedback via the second electrical signal to air mixer 14 to dilute sample air 12 with clean air 18 such that a constant reactant ion peak is observed by ion mobility spectrometer cell 30. The desired amount of reactant ion concentration may be shown for example in FIG. 4 wherein reactant ion peak curve 76 is shown. By maintaining a level or amplitude of the reactant ion in ion mobility spectrometer cell 30 saturation due to an excess concentration of sample molecules will be avoided or prevented. Circuit 60 functions to combine the sample ion peak such as curve 78 in FIG. 4 with the output signal of circuit 58 which controls the air mixer 14 to provide an output signal on lead 64 indicative of the concentration of the sample molecule such as methyl salicylate in sample air 12. A method and apparatus has been described for diluting sample air 12 with clean air 18 to provide a concentration of sample air 12 to the ion mobility spectrometer cell 30 which will not saturate the cell. Saturation is prevented by circuit 54 which monitors the reactant ion peak, the first elctrical signal, and circuit 58 which generates a feedback signal, the second electrical signal, to maintain the reactant ion peak at a predetermined level. The feedback signal is coupled to an air mixer 14 at the inlet to provide a predetermined concentration of sample air 12 with respect to clean air 18 at the inlet 26 of ion mobility spectrometer cell 30. Circuit 60 provides an output signal, the third electrical signal, indicative of the concentration of the sample molecule in sample gas 12 by combining the output of circuit 54 which provides an indication of the sample ion peak and the output of circuit 58 which provides the control signal to air mixer 14.
An ion mobility spectrometer is described incorporating an air mixer having a clean air inlet and a sample air inlet, an ion mobility spectrometer cell for generating reaction ions and sample ions which are subsequently measured in a drift region, a first circuit for measuring the reactant ion peak and the sample ion peak, a second circuit for generating a feedback control signal to the air mixer in response to the reactant ion peak and a third circuit for generating a signal indicative of concentration of the sample molecules in sample air at the inlet utilizing the sample ion peak and the feedback control signal to the air mixer. The invention overcomes the problem of limited dynamic range due to saturation of the ion mobility spectrometer cell.
Provide a concise summary of the essential information conveyed in the given context.
[ "GOVERNMENT CONTRACT This invention was made with Government support under Contract F33615-86-4526 awarded by the U.S. Air Force.", "The Government has certain rights in this invention.", "BACKGROUND OF THE INVENTION 1.", "Field of the Invention This invention relates to Ion Mobility Spectrometers and more particularly to extending the dynamic range of the ion mobility spectrometer by using an input sample air mixer which is controlled by an electrical signal.", "Description of the Prior Art Present ion mobility spectrometers have limited dynamic range and are easily saturated when the sample molecules exceed the number of reaction ions available to ionize the sample molecules.", "Normal sensitivities of ion mobility spectrometers is in the range of parts per billion.", "An ionizer in the reaction region generates reactant ions over a period of time which in turn are attracted by the affinity of the sample molecule which removes charge from the reactant ions to itself.", "The ionized sample molecules are then detected by their drift time in a drift region.", "A typical range of concentrations of the sample is less than 100 to 1.", "U.S. Pat. No. 4,259,573 which issued on Mar. 31, 1981 to J. M. Prober et al.", ", describes an accurate method of determining small concentrations of chemical compounds by plasma chromotography "Ion Mobility Spectrometry".", "Small, known increments of species A plus, optionally, another calibrant species are introduced in turn into the plasma chromotograph together with the unknown sample chemical and the respective changes of the amplitude or area of a characteristic ion peak of species A in the unknown sample are measured.", "U.S. Pat. No. 4,311,669 which issued on Jan. 19, 1982 to G. E. Spangler describes a sample inlet port of an ion mobility detector having a membrane interface.", "The sample which is included as a vapor component in a gas stream impinges on the exterior surface of the membrane and penetrates the membrane and is carried into the ion mobility spectrometer by means of a carrier gas which scrubs the interior surface of the membrane.", "U.S. Pat. No. 4,551,624 which issued on Nov. 5, 1985 to G. E. Spangler et al.", "describes an ion mobility spectrometer system wherein a reagent such as acetone and/or carbon tetrachloride is injected into the carrier gas prior to entering the reaction region.", "The reagent has a higher proton affinity, electron affinity, or acidity than contaminants in the sample gas, a lower proton affinity, electron affinity, or acidity than at least 1 constituent of the sample gas to be detected, and does not cluster with water disposed in the reagent source.", "SUMMARY OF THE INVENTION A method and apparatus is described for detecting ions comprising an air mixer having a first input port for receiving clean air and a second input port for receiving sample air, the air mixer having a control input responsive to electrical signals for controlling the mixture of clean air received from the first input port to sample air received from the second input port, the air mixer having an output port coupled to the inlet of a reaction region, the reaction region including an ionization source for generating ions from the mixed clean air and sample air to form reactant ions and sample ions from selected sample molecules in the sample air, a shutter grid for introducing ions from the reaction region into the drift region having an electric field for drifting the ions towards a collector with circuitry attached for measuring the amplitude and mobility of the reaction ions and sample ions in the drift region, the circuitry including means for generating a first electrical signal indicative of the reaction ion amplitude, a second circuit for generating a second electrical signal from the first electrical signal indicative of a desired air mixture of clean air to sample air in response to the amplitude of the first electrical signal, the second electrical signal coupled to the control input of the air mixer, and a third circuit coupled to the first and second electrical signals for generating a third electrical signal indicative of the concentration of the sample molecule in the sample air at the second input port.", "It is an object of the invention to extend the dynamic range of the ion mobility spectrometer by using at its input an air mixer with the ratio of sample air to clean air varied as a function of a selected output signal from the ion mobility spectrometer.", "It is a further object of the invention to utilize an input sample air mixer to dilute the sample being measured to prevent the sample from saturating the output of the ion mobility spectrometer.", "The concentration of the chemical in the sample air that is being measured is then determined by the air mixer ratio and a selected output signal from the ion mobility spectrometer.", "It is a further object of the invention to generate a feedback signal from the amplitude of the reactant ion output signal for diluting or premixing the input sample prior to entry into the ion mobility spectrometer.", "BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is one embodiment of the invention.", "FIG. 2 is a graph of a reactant ion peak from an ion mobility spectrometer.", "FIGS. 3-5 are graphs of the reactant ion peak and the sample ion peak from an ion mobility spectrometer.", "DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, an ion mobility spectrometer for detecting ions such as sample ions from sample air 12.", "An air mixer 14 has a first input port 16 for receiving clean air 18.", "Clean air 18 may be air which has been scrubbed to be free of sample molecules or may be a gas such as nitrogen free of sample molecules.", "A second input port 20 receives sample air 12 which may contain sample molecules of a chemical of unknown concentration.", "Sample air 12 might be a gas such as nitrogen and the sample molecules.", "Air mixer 14 may have valves for controlling the flow of clean air 18 and sample air 12 into air mixer 14 which are mixed together therein and vented through output port 22.", "Air mixer 14 has a control input responsive to electrical signals over lead 24 for controlling the mixture of clean air received from input port 16 and sample air received from input port 20.", "Air mixer 14 has an output port 22 coupled to the inlet 26 of reaction region 28 of ion mobility spectrometer cell 30.", "Reaction region 28 includes an ionization source such as a nickle 63 which emits beta particles which ionizes the clean air 18 to provide reaction ions in reaction region 28.", "The reaction ions in turn ionize sample molecules which have a stronger affinity for the charge on the reaction ions.", "A shutter grid 34 allows sample ions and reaction ions to pass from reaction region 28 to drift region 36.", "The ions travel in direction shown by arrow 37 toward collector 38.", "Reaction region 28 may include means for generating an electric field therein to move the ions towards shutter grid 34.", "Drift region 36 may include means for generating an electric field therein to move the ions towards collector 38.", "One example of an ion mobility spectrometer cell 30 is described in U.S. Pat. No. 4,378,499 which issued on Mar. 29, 1983 to G. E. Spangler et al.", "entitled "Chemical Conversion For Ion Mobility Detectors Using Surface Interactions"", "which is incorporated herein by reference to show the construction details and operation of an ion mobility spectrometer cell.", "Drift Gas 40 which may be for example dry nitorgen enters inlet 44 shown by arrow 42 into drift region 36 which exits vent 46 as shown by arrow 48.", "The clean air 18 and sample air 12 which enters inlet 26 of reaction region 28 is vented by vent 46 shown by arrow 50.", "The ions in the drift region 36 are collected by collector 38 and are neutralized.", "The neutralized molecules flow with the drift gas to vent 46.", "The voltage on collector 38 is carried over lead 52 to an input of circuit 54.", "Circuit 54 provides a means for measuring the amplitude and drift time of reactant ions and sample ions reaching collector 38.", "Circuit 54 generates a first electrical signal indicative of the reactant ion amplitude which is coupled over lead 56 to an input of circuit 58.", "Circuit 58 functions to generate a second electrical signal on lead 24 from the first electrical signal on lead 56 indicative of a desired air mixture in air mixer 14 of clean air to sample air in response to the amplitude of the first electrical signal.", "The second electrical signal from circuit 58 is coupled over lead 24 to the control input of air mixture 14 and to an input of circuit 60.", "Circuit 54 also generates a third electrical signal indicative of the sample ion amplitude which is coupled over lead 62 to an input of circuit 60.", "Circuit 60 functions to generate a fourth electrical signal on lead 64 indicative of the concentration of the sample molecules in sample air 12.", "Circuit 60 functions to combine mathematically the third electrical signal indicative of amplitude of the sample ion with the second electrical signal indicative of a desired air mixture to provide the fourth electrical signal.", "In operation of the ion mobility spectrometer 10, first clean air 18 was passed through air mixture 14 into reaction region 28 where reactant ions were generated and measured in drift region 36.", "FIG. 2 is a graph of the reactant ion peak shown by curve 68.", "In FIG. 2 the ordinant represents the response in units of current and the abscissa represents time.", "The electrical signal representative of the reactant ion peak shown by curve 68 would be provided on lead 52 to the input of circuit 58.", "In clean air using water chemistry, reactant ions form in both positive and negative operating modes.", "The reactant ions are ionized clusters of water molecules and nitrogen as described by S. H. Kim et al.", ""Mobility Behavior and Composition of Hydrated Positive Reactant Ions in Plasma Chromotography with Nitrogen Carrier Gas"", "Anal.", "Chem[.", "].1978,50.", "For the purposes of providing a test, an organic molecule methyl salicylate also known as oil of wintergreen was used as the sample molecule.", "Methyl salicylate is a much larger molecule than the reactant ions and has a lower mobility.", "Clean air 18 and sample air 12 containing methyl salicylate were mixed in air mixer 14 to provide a signature of 0.02 gamma which was passes into reaction region 28 wherein reactant ions were generated which in turn formed sample ions.", "The reactant ions and the sample ions were measured in drift region 36 and collected by collector 38.", "FIG. 3 is a graph of the response of the signal on lead 52.", "Curve 70 shows the reactant ion peak and curve 72 shows the sample ion peak wherein the sample molecule is methyl salicylae.", "In FIG. 3 the ordinant represents amplitude in units of current and the abscissa represents time.", "Generally, the number of ions generated in a unit of time in reaction region 28 is constant and therefore a limited number of molecules will become ionized prior to entry into the drift region 36.", "Thus the reduction of the amplitude peak of the reactant ion shown by curve 70 compared to curve 68 in FIG. 2 is due to the fact that reactant ions lost charge to form sample ions shown by curve 72 in FIG. 3. A further test was run wherein clean air 18 and sample air 12 was mixed in air mixer 14 to provide a concentration of methyl salicylate of 0.04 gamma which was passed into reaction region 28.", "The reactant ions and sample ions were measured in drift region 36 at collector 38.", "FIG. 4 shows the response of the electrical signal on lead 52.", "In FIG. 4 the ordinant represents amplitude in units of current and the abscissa represents time.", "The reactant ion peak is shown by curve 76 and the sample ion peak is shown by curve 78.", "It is noted that compared to FIG. 3 the reactant ion peak in FIG. 4 has diminished while the sample ion peak has increased.", "A further test was run wherein clean air 18 and sample air 12 was mixed in air mixer 14 to provide a concentration of methyl salicylate of 0.06 gamma which was passed into reaction region 28.", "The reactant ions and sample ions were measured in drift region 36 at collector 38.", "FIG. 5 shows a graph of the response on lead 52.", "In FIG. 5 the ordinant represents amplitude in units of current and the abscissa represents time.", "The reactant ion peak is shown by curve 80 and the sample ion peak is shown by curve 82.", "As compared to FIG. 4 the reactant ion peak 80 in FIG. 5 has diminished further while the sample ion peak has increased.", "At this point as shown in FIG. 5, very few reactant ions are left to be used to ionize sample molecules, therefore the ion mobility spectrometer cell 30 is very near saturation.", "Thus once the reactant ion peak disappears, presumably all reactant ions were used to ionize sample ions and additional sample molecules may be present which were not ionized due to the insufficiency of reactant ions.", "FIGS. 3 through 5 show that the total ion concentration of reactant ions and sample ions has remained essentially constant.", "Circuit 58 functions to provide feedback via the second electrical signal to air mixer 14 to dilute sample air 12 with clean air 18 such that a constant reactant ion peak is observed by ion mobility spectrometer cell 30.", "The desired amount of reactant ion concentration may be shown for example in FIG. 4 wherein reactant ion peak curve 76 is shown.", "By maintaining a level or amplitude of the reactant ion in ion mobility spectrometer cell 30 saturation due to an excess concentration of sample molecules will be avoided or prevented.", "Circuit 60 functions to combine the sample ion peak such as curve 78 in FIG. 4 with the output signal of circuit 58 which controls the air mixer 14 to provide an output signal on lead 64 indicative of the concentration of the sample molecule such as methyl salicylate in sample air 12.", "A method and apparatus has been described for diluting sample air 12 with clean air 18 to provide a concentration of sample air 12 to the ion mobility spectrometer cell 30 which will not saturate the cell.", "Saturation is prevented by circuit 54 which monitors the reactant ion peak, the first elctrical signal, and circuit 58 which generates a feedback signal, the second electrical signal, to maintain the reactant ion peak at a predetermined level.", "The feedback signal is coupled to an air mixer 14 at the inlet to provide a predetermined concentration of sample air 12 with respect to clean air 18 at the inlet 26 of ion mobility spectrometer cell 30.", "Circuit 60 provides an output signal, the third electrical signal, indicative of the concentration of the sample molecule in sample gas 12 by combining the output of circuit 54 which provides an indication of the sample ion peak and the output of circuit 58 which provides the control signal to air mixer 14." ]
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. This application is a division of application No. 07/836,895, filed Feb. 19, 1992, now U.S. Pat. No. 5,261,616. BACKGROUND OF THE INVENTION The present invention relates to composite hollow cylindrical structures, more particularly to composite hollow cylindrical structures which are rib-stiffened and to filament winding methods for fabrication thereof. Filament winding is a technique which is known in the art for the manufacture of cylindrical structures (e.g., tubes and pipes), spherical structures, and other surfaces of revolution. Typically, the filament winding process involves utilization of a resin bath through which dry fibers are passed and then wound; this type of filament winding is known as "wet winding." In this technique the wind angle, band width and tow tension are controlled. Incorporated herein by reference is an informative text on fiber composites: Agarwal, Bhagwan D., and Broutman, Lawrence J., Analysis and Performance of Fiber Composites, 2nd Ed., John Wiley & Sons, Inc., New York, 1990; see, especially, section 2.3.1.3 "Filament Winding," pp. 42-44. Filament winding has been used by the United States Navy for various applications. For example, a wet winding procedure has been utilized by the U. S. Navy for the Advanced Unmanned Search System Vehicle (AUSS). The U.S. Navy has also utilized a wet winding procedure in the fi lament winding process for the manufacturing of the Composite Propeller Drive Shaft. Manufacture of various types of composite structures having ribs or stiffeners is known in the art. In the manufacturing process for rib-stiffened flat structures, what is generally involved is the separate manufacture of the ribs and of the face sheets, followed by secondary bonding. A rib-stiffened configuration has also been considered for cylindrical applications. A typical approach for achieving a rib-stiffened cylindrical design involves first winding ribs onto a mandrel which has rib grooves machined in it. After the ribs are wound or fabricated, the rest of the cylindrical form is wound. The mandrel, which is typically sectional, is then disassembled and the cylinder is removed. With this type of design, however, internal connections are made either to the ribs or the skin itself; hence, there is a direct path for vibration energy to propagate from the interior to the exterior of the structural form. This approach is thus deficient for applications in which maximization of energy dissipation from the inside to the outside of the cylinder is desired. A process used in the filament winding of rib-stiffened cylinders which is similar to the one described above for flat shape applications is disclosed in a publication, incorporated herein by reference, from a 1986 Society of Manufacturing Engineers proceeding. See Harruff, P., Tsuchiyama T., and Spicola, F. C., "Filament Wound Torpedo Hull Structures," Fabricating Composites '86 Proceedings, Society of Manufacturing Engineers, Sept. 8-11, 1986, Baltimore, Md. This process requires the fabrication and curing of the skin and stiffeners, followed by the machining of the cylinder inner diameter and the rib outer diameter to high tolerance. After this is done, the ribs are carefully positioned and adhesively bonded to the skin. The materials used for the application disclosed by Harruff et al., it is noted, are a prepreg tape for the cylinder wall and a wet winding system for the ribs. As aforementioned herein, wet winding procedures have been used by the U.S. Navy for the Advanced Unmanned Search System Vehicle (AUSS) and the Composite Propeller Drive Shaft. The AUSS was a cylinder of constant thickness and no ribs. See Technical Report 1245, August 1988, Stachiw, J. D., and Frame, B., "Graphite-Fiber-Reinforced Plastic Pressure Hull Mod 2 for the Advanced Unmanned Search System Vehicle," Naval Ocean Systems Center, San Diego, Calif., incorporated herein by reference; see therein, especially, pages 16-21, and FIG. 18 on page 54 therein ("Schematic of Winding Operation"). For the manufacture of the Composite Propeller Drive Shaft, dry tows are passed through a resin bath to coat the tows. After tow impregnation they are fed onto the mandrel at various orientations to achieve the desired part. Incorporated herein by reference is Report No. DTRC-PASD-CR-1-88, Contract No. N00167-86-C-0150, Tulpinsky, Joseph F., and May, Marvin C., "Filament Winding Process for Composite Propeller Drive Shaft Sections," October 1986 to October 1987, prepared by Hercules, Inc. for David Taylor Naval Ship R & D Center; see, especially, pages 4-1 through 4-8 therein (Chapter 4.0 "Manufacturing"). The U.S. Air Force used the filament winding technique for the B-1B composite Rotary Launch Tube. Here the winding process utilized prepreg tape in favor of the wet winding technique in order to achieve a tighter control on fabricated properties. Incorporated herein by reference is Peters, S. T., Humphrey, W. D., and Foral, R. F., Filament Winding, Composite Structure Fabrication, Society for the Advancement of Material and Process Engineering, Covina, Calif. 1991; see, especially, pages 2-9, 2-12, 11-1 to 11-3. Although the above-described processes for manufacturing bodies of revolution have achieved satisfactory results, they have generally been discontinuous and time-consuming and have required precision equipment and machining. OBJECTS OF THE INVENTION In view of the foregoing, it is a principal object of the present invention to provide an improved rib-stiffened hollow cylinder construction and fabrication methodology. It is a further object of the present invention to provide an improved hollow cylinder construction and fabrication methodology for use as a mechanical vibrational energy-dissipating enclosure. Another object of this invention is to provide an improved hollow cylinder construction and fabrication methodology for use as a directionally controllable thermal energy-transmitting enclosure. A further object of this invention is to provide an improved hollow cylinder construction and fabrication methodology which admits of a continuous fabrication procedure. Another object of the present invention is to provide an improved hollow cylinder construction and fabrication methodology which would be advantageously suitable for such applications as, e.g., chemical or petro-chemical storage tanks, manned or unmanned submersible pressure hulls, manned or unmanned aircraft, and manned or unmanned spacecraft. SUMMARY OF THE INVENTION The present invention provides a multiple composite translated rib-stiffened cylinder with hollow core which may be fabricated in an unbroken procedure and is suitably used as a mechanical vibrational energy dissipating enclosure. The multi-cored, rib-stiffened cylindrical design according to this invention is capable not only of dissipating internal mechanical vibrational energy but also of minimizing the energy transmitted to the external environment. This invention provides a method, using a cylindrical mandrel, for fabricating a translated double rib-stiffened composite cylinder having a hollow core. "Circumferential" winding, as used herein, means in a direction or directions of selected filment orientation or orientations about the circumference of the cylinder. "Longitudinal winding, as used herein, means in the axial or generally axial direction of the cylinder. This method provided by the present invention comprises: Winding circumferentially an inner skin around the cylindrical mandrel; winding circumferentially a plurality of inner circumferential ribs around the inner skin, the inner circumferential ribs spaced apart longitudinally; positioning a pair of inner pin rings at the axial ends of the cylindrical mandrel, one inner pin ring at each axial end, each inner pin ring having a ring portion and a plurality of pins spaced apart circumferentially and projecting radially from the ring portion; winding longitudinally a plurality of inner longitudinal stringers, the inner longitudinal stringers transversely superposed on and contiguous with the inner circumferential ribs, the inner longitudinal stringers engaged with the pins of the inner pin ring and spaced apart circumferentially and correspondingly with the pins of the inner pin ring; winding circumferentially a pair of inner bands, the inner bands located longitudinally inward of and adjacent to the first pin rings; winding circumferentially an intermediate skin around the inner bands and the inner longitudinal stringers; winding circumferentially a plurality of outer circumferential ribs around the intermediate skin, the outer circumferential ribs spaced apart longitudinally and staggeringly with respect to the inner circumferential ribs; positioning a pair of outer pin rings at the axial ends of the cylindrical mandrel, .one outer pin ring at each axial end, each outer pin ring having a ring portion and a plurality of pins spaced apart circumferentially and projecting radially from the ring portion; winding longitudinally a plurality of outer longitudinal stringers, the outer longitudinal stringers transversely superposed on and contiguous with the outer circumferential ribs, the outer longitudinal stringers engaged with the pins of the outer pin ring and spaced apart circumferentially and correspondingly with the pins of said outer pin ring; winding circumferentially a pair of outer bands, the outer bands located longitudinally inward of and adjacent to the outer pin rings; and winding circumferentially an outer skin around the outer bands and the outer axial stringers. In fact, this invention provides a method, using a cylindrical mandrel, for fabricating a translated rib-stiffened composite cylinder having a hollow core which is multiple-layered. The cylinder can be double-layered, triple-layered, quadruple-layered, quintuple-layered, sextuple-layered, septuple-layered, or layered in any greater multiple. This method comprises: (a) winding circumferentially an inner skin around the cylindrical mandrel, this step (a) forming the inner layer of the composite cylinder; (b) winding circumferentially a plurality of first circumferential ribs around the inner skin, the first circumferential ribs spaced apart longitudinally; (c) positioning a pair of first pin rings at the axial ends of the cylindrical mandrel, one first pin ring at each axial end, each first pin ring having a ring portion and a plurality of pins spaced apart circumferentially and projecting radially from the ring portion; (d) winding longitudinally a plurality of first longitudinal stringers, the first longitudinal stringers transversely superposed on and contiguous with the first circumferential ribs, the first longitudinal stringers engaged with the pins of the first pin ring and spaced apart circumferentially and correspondingly with the pins of the first pin ring; (e) winding circumferentially a pair of first bands, the first bands located longitudinally inward of and adjacent to the first pin rings; (f) winding circumferentially a first outer skin around the first bands and the first axial stringers, these steps (b) to (f) inclusive forming the first outer layer of the composite cylinder, the first outer layer including the first circumferential ribs, the first pin rings, the first longitudinal stringers, the first bands, and the first outer skin; (g) winding circumferentially a plurality of second circumferential ribs around the second skin, the second circumferential ribs spaced apart longitudinally and staggeringly with respect to the first circumferential ribs; (h) positioning a pair of second pin rings at the axial ends of the cylindrical mandrel, one second pin ring at each axial end, each second pin ring having a ring portion and a plurality of pins spaced apart circumferentially and projecting radially from the ring portion; (i) winding longitudinally a plurality of second longitudinal stringers, the second longitudinal stringers transversely superposed on and contiguous with the second circumferential ribs, the second longitudinal stringers engaged with the pins of the second pin ring and spaced apart circumferentially and correspondingly with the pins of the second pin ring; (j) winding circumferentially a pair of second bands, the second bands located longitudinally inward of and adjacent to the second pin rings; (k) winding circumferentially a second outer skin around the second bands and the second longitudinal stringers these steps (g) to (k) inclusive forming the second outer layer of the composite cylinder, the second outer layer including the second circumferential ribs, the second pin rings, the second longitudinal stringers, the second bands, and the second outer skin; and (1) repeating steps (g) to (k) inclusive any number of times, each repetition of steps (g) to (k) inclusive forming a next outer layer of the composite cylinder, each next outer layer being radially outward of the previous outer layer, the previous outer layer being the radially outermost outer layer prior to the repetition of steps (g) to (k) inclusive, the previous outer layer including the previous circumferential ribs, the previous pin rings, the previous longitudinal stringers, the previous bands, and the previous outer skin, the next outer layer including next circumferential ribs, next pin rings, next longitudinal stringers, next bands, and a next outer skin, the next circumferential ribs spaced apart longitudinally and staggeringly with respect to previous circumferential ribs. The present invention also provides a multiple-layered, translated rib-stiffened composite cylinder having a hollow core, the composite cylinder being produced by the above-said method for fabricating a translated rib-stiffened composite cylinder having a hollow core which is multiple-layered. The composite cylinder comprises: An inner layer which includes an inner skin; and at least one outer layer, each said outer layer including a plurality of circumferential ribs, a pair of pin rings, a plurality of longitudinal stringers, a pair of bands, and an outer skin. The multiple-rib cylinder assembly of the present invention, featuring a multiple-layer rib-stiffener configuration, advantageously minimizes the vibrational energy transmitted to the environment from internal vibrating structures. The multiple stiffener design achieves maximum dissipation of vibrational energy from the inside of the cylinder to the outside. Any vibrational energy that is incident at the inner surface is not directly connected to the outer skin. For example, in the case of the double stiffener design of this invention, the vibrational energy is initially passed through to the middle skin at the rib-stiffeners, which in effect is a reduced energy source. After this energy is passed onto the middle skin, it again can only pass onto the outer skin by traveling through the rib-stiffeners. Once it is passed through these rib-stiffeners, the outer skin is excited. There is dissipation in the energy that is transmitted to the outer skin for three reasons. Firstly, there is no direct connection between the source and the outer skin. Secondly, because of the vibration damping of the composite, and the fact that energy is dissipated over a distance, the larger the distance that the vibration travels, the lower the magnitude of the vibration. In this manner, the energy that is finally transmitted to the outer skin is significantly less, which will result in a quieter (and, as the case may be, stealthier) structure. Thirdly, because of the path that the internal vibrational motion must follow, there may be a tendency for conversion of interior longitudinal vibrational motion, which is difficult to dissipate to flexural vibrational motion, which is dissipated rather efficiently by composite materials. Moreover, the multi-layered, rib-stiffened composite cylinder assembly of the present invention provides for easier thermal management through the use of metallic inner skin with all other parts being composite; alternatively, composite materials such as graphite fibers in an epoxy could also be used for the inner skin for thermal management concerns. In this manner, the heat in the interior of the cylinder can be transmitted to a specific location on the cylinder or can be dissipated to appear to be of other shape than it actually is. This results because the composite is insulating in directions normal to the fiber direction and will not transmit the heat through it. All (or virtually all) of the heat can be made to exit at specific location(s). Additionally, the present invention features a material winding fabrication methodology which admits of continuous winding and layering. This invention thus provides an efficient fabrication method for making composite cylindrical sections in a continuous process. It should also be emphasized that the multiple wall construction of the present invention provides a damage-tolerant design. A notable feature of this invention is the multiplicity of layers having rib-stiffeners which are translatedly disposed in relation to the rib-stiffeners of each adjacent layer. The outer skin provides protection to the interior skins from shock or foreign object impact because direct structural connection is minimized; hence, significant catastrophic damage to the rest of the structure is minimized. Other objects, advantages and features of this invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS In order that the present invention may be clearly understood, it will now be described, by way of example, with reference to the accompanying drawings, wherein like numbers indicate the same or similar components, and wherein: FIG. 1 through FIG. 8 are schematic perspective views representing the steps of the fabrication methodology of the present invention. FIG. 9 is a diagrammatic axially transverse sectional view of the double-ribbed composite cylinder of this invention, taken along the plane of line 9--9 in FIG. 8. FIG. 10 is a diagrammatic partial perspective detail view of the mandrel and pin ring shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION Cylindrical workpiece 18, shown in various stages of completion in FIG. 1 through FIG. 8, is outward of and coaxial with mandrel 20. Referring now to FIG. 1, inner skin 22 is made of fibrous material. Unidirectional fibers are wound around cylindrical mandrel 20 to form a continuous skin, inner skin 22. Inner skin 22 of cylinder workpiece 18 has an outer surface defining a cylindrical shape which is coaxial with mandrel 20. As the term is used herein, a "fibrous" material is fiber, filament or tape of any appropriate material composition. In the context of circumferential winding, for most embodiments of the present invention the fibrous material has a width less than length 1 of completed cylinder 18, shown in FIG. 8; however, for some embodiments, the fibrous material which is circumferentially wound to form inner skin 22 or a subsequent continuous skin is a sheet-like material having a width commensurate with the longitudinal expanse of mandrel 20 and approximately equal to length 1 of completed cylinder workpiece 18. In the context of longitudinal winding, the width of the material being wound is generally normal to the longitudinal expanse of mandrel 20 as well as to the longitudinal expanse of the cylinder workpiece 18; here, a fibrous material has a width less than the circumference of the cylindrical shape along which the fibrous material is being wound. Hence, when the fibrous material is engaged with inner pins 30 and longitudinally wound along the cylindrical shape defined by the outer surfaces of inner circumferential ribs 24, as shown in FIG. 3, the fibrous material has a width less than the circumference of this cylindrical shape corresponding to inner circumferential ribs 24; similarly, when the fibrous material is engaged with outer pins 44 and longitudinally wound along the cylindrical shape defined by the outer surfaces of outer circumferential ribs 38, as shown in FIG. 7, the fibrous material has a width less than the circumference of this cylindrical shape corresponding to outer circumferential ribs 38. It is emphasized herein that any degree of commonality or differentiation between or among any of the material compositions actually used for the fibrous materials may be appropriate in accordance with a given embodiment of the present invention; hence, use herein, for example, of the terms "first" fibrous material, "second" fibrous material, and "third" fibrous material is not intended to suggest that the "first" fibrous material necessarily is either the same as or different from the "second" fibrous material, or that the "second" fibrous material necessarily is either the same as or different from the "third" fibrous material, or that the "first" fibrous material necessarily is either the same as or different from the "third" fibrous material. After inner skin 22 of appropriate thickness is wound, inner circumferential ribs 24 running circumferentially around inner skin 22 are wound, using a filament-winding or tape-laying machine. With reference to FIG. 2, a second fibrous material is wound circumferentially around the cylindrical shape defined by the outer surface of inner skin 22 so as to form a plurality of inner circumferential ribs 24 spaced apart axially and having equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20. FIG. 2 schematically illustrates inner circumferential ribs 24 wound over inner skin 22. Inner circumferential ribs 24 can be wound with or without the use of a dissolvable or sectional mold which is placed outside inner skin 22. If a dissolvable or sectional mold is utilized, this is removed after winding inner circumferential ribs 24. Referring to FIG. 3, two inner pin rings 26 are positioned, one at each axial end of mandrel 20. Each inner pin ring 26 has an inner ring 28 portion and a plurality of inner pins 30 spaced apart circumferentially and projecting radially from inner ring 28, as shown in FIG. 10. Each inner ring 28 has an outer surface defining a cylindrical shape which is coaxial with mandrel 20 and approximately equiradial with the cylindrical shape defined by said outer surfaces of inner circumferential ribs 24. A third fibrous material is engaged with inner pins 30 and wound longitudinally along the cylindrical shape defined by the outer surfaces of inner circumferential ribs 24 so as to form a plurality of inner longitudinal stringers 32 which are spaced apart circumferentially and correspondingly with inner pins 30 and have equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20. It is emphasized that the present invention provides a unique methodology of allowing for tape or fiber placement over inner circumferential ribs 24, thus succeeding in winding intermediate skin 36 on top of circumferential ribs 24. Intermediate skin 36 cannot merely be wound directly onto inner circumferential ribs 24, since a continuous surface does not exist onto which the tape or fibers can be positioned. The present invention accomplishes this with the use of two pin rings 26, one positioned at each end of the wound piece. Inner pin rings 26 have a small cylindrical section, inner rings 28, of diameter approximately equal to that of the wound part. A series of inner pins 30, for some embodiments preferably equally spaced apart, extend in the radial direction outward from inner rings 28. Fibers or tapes are wound along the axis of the cylinder at some spacing, for some embodiments preferably about 1 inch, depending on dimensions. As the tape or filament winding machine makes a pass along the axis of the cylinder, the mandrel rotates a specified angular amount and traverses again along the axis of the cylinder. Typically, in the absence of inner pin rings 26, such a fiber or tape position would not remain, since it is not a geodesic path; however, in accordance with this invention, inner pin rings 26 keep the fibers or tapes in their axial position. Reference now being made to FIG. 4, a fourth fibrous material is wound circumferentially around the cylindrical shape defined by the outer surfaces of inner longitudinal stringers 32 so as to form a pair of inner circumferential bands 34 , (only one of the pair shown in the figure), located longitudinally inward of and adjacent to inner pin rings 26, inner circumferential bands 34 being spaced apart longitudinally and having equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20. Tapes or fibers are wound in the hoop direction at the ends of cylinder workpiece 18 to form inner circumferential bands 34, which provide a net force on inner longitudinal stringers 32 in the radial direction toward the interior of the cylinder. Another continuous skin is wound over top inner longitudinal stringers 32 and inner circumferential bands 34, referring now to FIG. 5. Here, a fifth fibrous material is wound circumferentially around the cylindrical shape defined by the outer surfaces of inner longitudinal stringers 32 and inner circumferential bands 34 so as to form intermediate skin 36 having an outer surface defining a cylindrical shape which is coaxial with mandrel 20. At this point, referring to FIG. 5, cylinder workpiece 18 comprises inner skin 22, a plurality of inner circumferential ribs 24, a pair of inner pin rings 26, a plurality of inner longitudinal stringers 32, a pair of inner circumferential bands 34, and intermediate skin 36. In order to add another ribbed layer to cylinder workpiece 18, steps pertaining to circumferential winding of ribs, positioning of pin rings, longitudinal winding of longitudinal stringers, circumferential winding of bands, and circumferential winding of a skin, are essentially repeated. Referring to FIG. 6 and FIG. 9, a second set of ribs is wound over the skin, but with their positions displaced relative to the ribs located axially inward thereof. Here a sixth fibrous material is wound circumferentially around the cylindrical shape defined by the outer surface of intermediate skin 36 so as to form a plurality of outer circumferential ribs 38. Outer circumferential ribs 38 are spaced apart longitudinally and staggeringly with respect to inner circumferential ribs 24 and have equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20. The specific positions of outer circumferential ribs 38 in relation to inner circumferential ribs 24 may be selected in accordance with both acoustical and structural design considerations. Selection of numbers and material compositions of inner circumferential ribs 24 and outer circumferential ribs 38 may also be relevant to these design considerations. For some embodiments, placement of outer circumferential ribs 38 is preferably translatedly uniform in relation to placement of inner circumferential ribs 24. For other embodiments of this invention, outer circumferential bands 38 are positioned variably or randomly in relation to successive inner circumferential ribs 24; in some embodiments and applications variable or random rib translation may provide enhanced vibrational energy dissipation. Also, for many embodiments of this invention inner circumferential ribs 24 and outer circumferential ribs 38 preferably provide stiffening for the composite cylinder with a minimum of weight. Referring to FIG. 7, two outer pin rings 40 are positioned, one at each axial end of mandrel 20. Each outer pin ring 40 has an outer ring 42 portion and a plurality of outer pins 44 spaced apart circumferentially and projecting radially from outer ring 42, referring again to FIG. 10, which may be viewed as generally representative of the pin ring configuration in accordance with this invention. Each outer ring 42 has an outer surface defining a cylindrical shape which is coaxial with mandrel 20 and approximately equiradial with the cylindrical shape defined by said outer surfaces of outer circumferential ribs 38. A second set of longitudinal stringers is wound in place with the use of the pin ring assembly, again resulting in a cylinder workpiece 18 structure such as that shown in FIG. 7. Here, a seventh fibrous material is engaged with outer pins 44 and wound longitudinally along the cylindrical shape defined by the outer surfaces of outer circumferential ribs 38 so as to form a plurality of outer longitudinal stringers 46 which are spaced apart circumferentially and correspondingly with outer pins 44 and have equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20. It is emphasized that the pins for any of the pairs of pin rings in accordance with this invention may be relatively distantly spaced apart, or relatively closely spaced apart, for various embodiments of this invention; hence, the longitudinal stringers which engage a particular pair of pin rings will be correspondingly distantly or closely spaced apart, and may even be contiguous, with respect to each other. Therefore, for example, for some embodiments longitudinal stringers 30 form a continuous or substantially continuous surface if the spacings between pins 30 are sufficiently small and the band widths of longitudinal stringers 32 are sufficiently great; similarly, longitudinal stringers 46 form a continuous or substantially continuous surface if the spacings between pins 40 are sufficiently small and the band widths of longitudinal stringers 46 are sufficiently great. Reference again being made to FIG. 4, which may be viewed as generally representative of circumferential winding of circumferential bands in accordance with this invention, an eighth fibrous material is wound circumferentially around the cylindrical shape defined by the outer surfaces of outer longitudinal stringers 46 so as to form a pair of outer circumferential bands 48 located longitudinally inward of and adjacent to outer pin rings 40, outer circumferential bands 48 being spaced apart longitudinally and having equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20. Thus, tapes or fibers are again wound in the hoop direction at the ends of cylinder workpiece 18, this time to form outer circumferential bands 48, which provide a net force on outer longitudinal stringers 46 in the radial direction toward the interior of the cylinder. Another continuous skin is wound over top outer longitudinal stringers 46 and outer circumferential bands 48, now referring to FIG. 8, which shows the completion of cylinder workpiece 18 as a double-layered, translated rib-stiffened composite cylinder. Here, a ninth fibrous material is wound circumferentially around the cylindrical shape defined by the outer surfaces of outer longitudinal stringers 46 and outer circumferential bands 48 so as to form outer skin 50 having an outer surface defining a cylindrical shape which is coaxial with mandrel 20. Accordingly, in this example a translated double rib-stiffened composite cylinder having a hollow core has been fabricated. This composite cylinder comprises: inner skin 22; a plurality of inner circumferential ribs 24 located radially outwardly adjacent to inner skin 22 and spaced apart longitudinally; a pair of inner pin rings 26 located at the axial ends of composite cylinder workpiece 18, one inner pin ring 26 at each axial end, each inner pin ring 26 having an inner ring 28 portion and a plurality of inner pins 30 spaced apart circumferentially and projecting radially from inner ring 28; a plurality of inner longitudinal stringers 32 located radially outwardly adjacent to inner circumferential ribs 24, inner longitudinal stringers 32 engaged with inner pins 30 and spaced apart circumferentially and correspondingly with inner pins 30; a pair of inner circumferential bands 34 located radially outwardly adjacent to inner longitudinal stringers 32 and longitudinally inwardly adjacent to inner pin rings 26; intermediate skin 36 located radially outwardly adjacent to inner circumferential bands 34 and inner longitudinal stringers 32; a plurality of outer circumferential ribs 48 located radially outwardly adjacent to intermediate skin 36, outer circumferential ribs 48 spaced apart longitudinally and staggeringly with respect to inner circumferential ribs 24; a pair of outer pin rings 40 located at the axial ends of composite cylinder workpiece 18, one outer pin ring 40 at each axial end, each outer pin ring 40 having an outer ring 42 portion and a plurality of outer pins 44 spaced apart circumferentially and projecting radially from outer ring 42; a plurality of outer longitudinal stringers 46 located radially outwardly adjacent to outer circumferential ribs 38, outer longitudinal stringers 46 engaged with outer pins 44 and spaced apart circumferentially and correspondingly with outer pins 44; a pair of outer circumferential bands 48 located radially outwardly adjacent to outer longitudinal stringers 46 and longitudinally inwardly adjacent to outer pin rings 40; and outer skin 50 located radially outwardly adjacent to outer circumferential bands 48 and outer longitudinal stringers 46. It is reemphasized that the composite cylinder in accordance with the present invention is a translated multiple rib-stiffened composite cylinder having any plural number of ribbed layers. Hence, appropriate repetition of steps in accordance with this invention succeeds in conversion of the completed double-layered, translated rib-stiffened composite cylinder in the above example to a triple-layered cylinder, for example, which further comprises: a plurality of first additional outer circumferential ribs located radially outwardly adjacent to outer skin 50 and spaced apart longitudinally and staggeringly with respect to outer circumferential ribs; a pair of first additional outer pin rings located at the axial ends of cylinder workpiece 18, one first additional outer pin ring at each axial end, each first additional outer pin ring having a ring portion and a plurality of pins spaced apart circumferentially and projecting radially from the ring portion; a plurality of first additional outer longitudinal stringers located radially outwardly adjacent to the first additional outer circumferential ribs, the first additional outer longitudinal stringers engaged with the pins of the first additional outer pin rings and spaced apart circumferentially and correspondingly with the pins of the first additional outer pin rings; a pair of first additional outer bands located radially outwardly adjacent to the first additional outer longitudinal stringers and longitudinally inwardly adjacent to the first additional outer pin rings; and a first additional outer skin located radially outwardly adjacent to the first additional outer bands and the first additional outer longitudinal stringers. Accordingly, in order to add each succeeding ribbed layer to cylinder workpiece 18, steps pertaining to circumferential winding of ribs, positioning of pin rings, longitudinal winding of longitudinal stringers, circumferential winding of bands, and circumferential winding of a skin, are appropriately repeated in accordance with this invention. Each repetition of steps forms a next outer layer of the composite cylinder, each next outer layer being radially outward of the previous other layer, the previous outer layer being the radially outermost outer layer prior to repetition of these steps. The previous outer layer includes previous circumferential ribs, previous pin rings, previous longitudinal stringers, previous bands, and a previous outer skin; the next outer layer includes the next circumferential ribs, the next pin rings, the next longitudinal stringers, the next bands, and the next outer skin, the next circumferential ribs spaced apart longitudinally and staggeringly with respect to the previous circumferential ribs. Other embodiments of this invention will be apparent to those skilled in the art from a consideration of this specification or practice of the invention disclosed herein. Various omissions, modifications and changes to the principles described may be made by one skilled in the art without departing from the true scope and spirit of the invention which is indicated by the following claims.
A multiple-layered, translatedly rib-stiffened, composite hollow cylinder d method for fabrication thereof utilizing filament winding techniques known in the art. An inner skin is wound over a mandrel; then, circumferential ribs are wound over the inner skin, pin rings are placed at the axial ends of the mandrel, longitudinal stringers are engaged with the pin rings and wound over the circumferential ribs, circumferential bands are wound near the axial ends over the longitudinal stringers, and another skin is wound over the circumferential bands and longitudinal stringers; these steps, commencing with the winding of circumferential ribs and concluding with the winding of an additional skin, are repeated as many times as desired, each repetition forming an additional layer, with the circumferential ribs for each additional layer being longitudinally staggered in relation to the circumferential ribs for the previous layer. The cylinder in accordance with this invention is a superior enclosure in terms of mechanical vibrational energy dissipation, directionally controllable thermal energy transmission, and structural damage tolerance; moreover, it advantageously permits a continuous fabrication procedure.
Provide a concise summary of the essential information conveyed in the given context.
[ "The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.", "This application is a division of application No. 07/836,895, filed Feb. 19, 1992, now U.S. Pat. No. 5,261,616.", "BACKGROUND OF THE INVENTION The present invention relates to composite hollow cylindrical structures, more particularly to composite hollow cylindrical structures which are rib-stiffened and to filament winding methods for fabrication thereof.", "Filament winding is a technique which is known in the art for the manufacture of cylindrical structures (e.g., tubes and pipes), spherical structures, and other surfaces of revolution.", "Typically, the filament winding process involves utilization of a resin bath through which dry fibers are passed and then wound;", "this type of filament winding is known as "wet winding.", """, "In this technique the wind angle, band width and tow tension are controlled.", "Incorporated herein by reference is an informative text on fiber composites: Agarwal, Bhagwan D., and Broutman, Lawrence J., Analysis and Performance of Fiber Composites, 2nd Ed.", ", John Wiley &", "Sons, Inc., New York, 1990;", "see, especially, section 2.3[.", "].1.3 "Filament Winding,"", "pp. 42-44.", "Filament winding has been used by the United States Navy for various applications.", "For example, a wet winding procedure has been utilized by the U. S. Navy for the Advanced Unmanned Search System Vehicle (AUSS).", "The U.S. Navy has also utilized a wet winding procedure in the fi lament winding process for the manufacturing of the Composite Propeller Drive Shaft.", "Manufacture of various types of composite structures having ribs or stiffeners is known in the art.", "In the manufacturing process for rib-stiffened flat structures, what is generally involved is the separate manufacture of the ribs and of the face sheets, followed by secondary bonding.", "A rib-stiffened configuration has also been considered for cylindrical applications.", "A typical approach for achieving a rib-stiffened cylindrical design involves first winding ribs onto a mandrel which has rib grooves machined in it.", "After the ribs are wound or fabricated, the rest of the cylindrical form is wound.", "The mandrel, which is typically sectional, is then disassembled and the cylinder is removed.", "With this type of design, however, internal connections are made either to the ribs or the skin itself;", "hence, there is a direct path for vibration energy to propagate from the interior to the exterior of the structural form.", "This approach is thus deficient for applications in which maximization of energy dissipation from the inside to the outside of the cylinder is desired.", "A process used in the filament winding of rib-stiffened cylinders which is similar to the one described above for flat shape applications is disclosed in a publication, incorporated herein by reference, from a 1986 Society of Manufacturing Engineers proceeding.", "See Harruff, P., Tsuchiyama T., and Spicola, F. C., "Filament Wound Torpedo Hull Structures,"", "Fabricating Composites '86 Proceedings, Society of Manufacturing Engineers, Sept.", "8-11, 1986, Baltimore, Md.", "This process requires the fabrication and curing of the skin and stiffeners, followed by the machining of the cylinder inner diameter and the rib outer diameter to high tolerance.", "After this is done, the ribs are carefully positioned and adhesively bonded to the skin.", "The materials used for the application disclosed by Harruff et al.", ", it is noted, are a prepreg tape for the cylinder wall and a wet winding system for the ribs.", "As aforementioned herein, wet winding procedures have been used by the U.S. Navy for the Advanced Unmanned Search System Vehicle (AUSS) and the Composite Propeller Drive Shaft.", "The AUSS was a cylinder of constant thickness and no ribs.", "See Technical Report 1245, August 1988, Stachiw, J. D., and Frame, B., "Graphite-Fiber-Reinforced Plastic Pressure Hull Mod 2 for the Advanced Unmanned Search System Vehicle,"", "Naval Ocean Systems Center, San Diego, Calif.", ", incorporated herein by reference;", "see therein, especially, pages 16-21, and FIG. 18 on page 54 therein ("Schematic of Winding Operation").", "For the manufacture of the Composite Propeller Drive Shaft, dry tows are passed through a resin bath to coat the tows.", "After tow impregnation they are fed onto the mandrel at various orientations to achieve the desired part.", "Incorporated herein by reference is Report No. DTRC-PASD-CR-1-88, Contract No. N00167-86-C-0150, Tulpinsky, Joseph F., and May, Marvin C., "Filament Winding Process for Composite Propeller Drive Shaft Sections,"", "October 1986 to October 1987, prepared by Hercules, Inc. for David Taylor Naval Ship R &", "D Center;", "see, especially, pages 4-1 through 4-8 therein (Chapter 4.0 "Manufacturing").", "The U.S. Air Force used the filament winding technique for the B-1B composite Rotary Launch Tube.", "Here the winding process utilized prepreg tape in favor of the wet winding technique in order to achieve a tighter control on fabricated properties.", "Incorporated herein by reference is Peters, S. T., Humphrey, W. D., and Foral, R. F., Filament Winding, Composite Structure Fabrication, Society for the Advancement of Material and Process Engineering, Covina, Calif.", "1991;", "see, especially, pages 2-9, 2-12, 11-1 to 11-3.", "Although the above-described processes for manufacturing bodies of revolution have achieved satisfactory results, they have generally been discontinuous and time-consuming and have required precision equipment and machining.", "OBJECTS OF THE INVENTION In view of the foregoing, it is a principal object of the present invention to provide an improved rib-stiffened hollow cylinder construction and fabrication methodology.", "It is a further object of the present invention to provide an improved hollow cylinder construction and fabrication methodology for use as a mechanical vibrational energy-dissipating enclosure.", "Another object of this invention is to provide an improved hollow cylinder construction and fabrication methodology for use as a directionally controllable thermal energy-transmitting enclosure.", "A further object of this invention is to provide an improved hollow cylinder construction and fabrication methodology which admits of a continuous fabrication procedure.", "Another object of the present invention is to provide an improved hollow cylinder construction and fabrication methodology which would be advantageously suitable for such applications as, e.g., chemical or petro-chemical storage tanks, manned or unmanned submersible pressure hulls, manned or unmanned aircraft, and manned or unmanned spacecraft.", "SUMMARY OF THE INVENTION The present invention provides a multiple composite translated rib-stiffened cylinder with hollow core which may be fabricated in an unbroken procedure and is suitably used as a mechanical vibrational energy dissipating enclosure.", "The multi-cored, rib-stiffened cylindrical design according to this invention is capable not only of dissipating internal mechanical vibrational energy but also of minimizing the energy transmitted to the external environment.", "This invention provides a method, using a cylindrical mandrel, for fabricating a translated double rib-stiffened composite cylinder having a hollow core.", ""Circumferential"", "winding, as used herein, means in a direction or directions of selected filment orientation or orientations about the circumference of the cylinder.", ""Longitudinal winding, as used herein, means in the axial or generally axial direction of the cylinder.", "This method provided by the present invention comprises: Winding circumferentially an inner skin around the cylindrical mandrel;", "winding circumferentially a plurality of inner circumferential ribs around the inner skin, the inner circumferential ribs spaced apart longitudinally;", "positioning a pair of inner pin rings at the axial ends of the cylindrical mandrel, one inner pin ring at each axial end, each inner pin ring having a ring portion and a plurality of pins spaced apart circumferentially and projecting radially from the ring portion;", "winding longitudinally a plurality of inner longitudinal stringers, the inner longitudinal stringers transversely superposed on and contiguous with the inner circumferential ribs, the inner longitudinal stringers engaged with the pins of the inner pin ring and spaced apart circumferentially and correspondingly with the pins of the inner pin ring;", "winding circumferentially a pair of inner bands, the inner bands located longitudinally inward of and adjacent to the first pin rings;", "winding circumferentially an intermediate skin around the inner bands and the inner longitudinal stringers;", "winding circumferentially a plurality of outer circumferential ribs around the intermediate skin, the outer circumferential ribs spaced apart longitudinally and staggeringly with respect to the inner circumferential ribs;", "positioning a pair of outer pin rings at the axial ends of the cylindrical mandrel, .", "one outer pin ring at each axial end, each outer pin ring having a ring portion and a plurality of pins spaced apart circumferentially and projecting radially from the ring portion;", "winding longitudinally a plurality of outer longitudinal stringers, the outer longitudinal stringers transversely superposed on and contiguous with the outer circumferential ribs, the outer longitudinal stringers engaged with the pins of the outer pin ring and spaced apart circumferentially and correspondingly with the pins of said outer pin ring;", "winding circumferentially a pair of outer bands, the outer bands located longitudinally inward of and adjacent to the outer pin rings;", "and winding circumferentially an outer skin around the outer bands and the outer axial stringers.", "In fact, this invention provides a method, using a cylindrical mandrel, for fabricating a translated rib-stiffened composite cylinder having a hollow core which is multiple-layered.", "The cylinder can be double-layered, triple-layered, quadruple-layered, quintuple-layered, sextuple-layered, septuple-layered, or layered in any greater multiple.", "This method comprises: (a) winding circumferentially an inner skin around the cylindrical mandrel, this step (a) forming the inner layer of the composite cylinder;", "(b) winding circumferentially a plurality of first circumferential ribs around the inner skin, the first circumferential ribs spaced apart longitudinally;", "(c) positioning a pair of first pin rings at the axial ends of the cylindrical mandrel, one first pin ring at each axial end, each first pin ring having a ring portion and a plurality of pins spaced apart circumferentially and projecting radially from the ring portion;", "(d) winding longitudinally a plurality of first longitudinal stringers, the first longitudinal stringers transversely superposed on and contiguous with the first circumferential ribs, the first longitudinal stringers engaged with the pins of the first pin ring and spaced apart circumferentially and correspondingly with the pins of the first pin ring;", "(e) winding circumferentially a pair of first bands, the first bands located longitudinally inward of and adjacent to the first pin rings;", "(f) winding circumferentially a first outer skin around the first bands and the first axial stringers, these steps (b) to (f) inclusive forming the first outer layer of the composite cylinder, the first outer layer including the first circumferential ribs, the first pin rings, the first longitudinal stringers, the first bands, and the first outer skin;", "(g) winding circumferentially a plurality of second circumferential ribs around the second skin, the second circumferential ribs spaced apart longitudinally and staggeringly with respect to the first circumferential ribs;", "(h) positioning a pair of second pin rings at the axial ends of the cylindrical mandrel, one second pin ring at each axial end, each second pin ring having a ring portion and a plurality of pins spaced apart circumferentially and projecting radially from the ring portion;", "(i) winding longitudinally a plurality of second longitudinal stringers, the second longitudinal stringers transversely superposed on and contiguous with the second circumferential ribs, the second longitudinal stringers engaged with the pins of the second pin ring and spaced apart circumferentially and correspondingly with the pins of the second pin ring;", "(j) winding circumferentially a pair of second bands, the second bands located longitudinally inward of and adjacent to the second pin rings;", "(k) winding circumferentially a second outer skin around the second bands and the second longitudinal stringers these steps (g) to (k) inclusive forming the second outer layer of the composite cylinder, the second outer layer including the second circumferential ribs, the second pin rings, the second longitudinal stringers, the second bands, and the second outer skin;", "and (1) repeating steps (g) to (k) inclusive any number of times, each repetition of steps (g) to (k) inclusive forming a next outer layer of the composite cylinder, each next outer layer being radially outward of the previous outer layer, the previous outer layer being the radially outermost outer layer prior to the repetition of steps (g) to (k) inclusive, the previous outer layer including the previous circumferential ribs, the previous pin rings, the previous longitudinal stringers, the previous bands, and the previous outer skin, the next outer layer including next circumferential ribs, next pin rings, next longitudinal stringers, next bands, and a next outer skin, the next circumferential ribs spaced apart longitudinally and staggeringly with respect to previous circumferential ribs.", "The present invention also provides a multiple-layered, translated rib-stiffened composite cylinder having a hollow core, the composite cylinder being produced by the above-said method for fabricating a translated rib-stiffened composite cylinder having a hollow core which is multiple-layered.", "The composite cylinder comprises: An inner layer which includes an inner skin;", "and at least one outer layer, each said outer layer including a plurality of circumferential ribs, a pair of pin rings, a plurality of longitudinal stringers, a pair of bands, and an outer skin.", "The multiple-rib cylinder assembly of the present invention, featuring a multiple-layer rib-stiffener configuration, advantageously minimizes the vibrational energy transmitted to the environment from internal vibrating structures.", "The multiple stiffener design achieves maximum dissipation of vibrational energy from the inside of the cylinder to the outside.", "Any vibrational energy that is incident at the inner surface is not directly connected to the outer skin.", "For example, in the case of the double stiffener design of this invention, the vibrational energy is initially passed through to the middle skin at the rib-stiffeners, which in effect is a reduced energy source.", "After this energy is passed onto the middle skin, it again can only pass onto the outer skin by traveling through the rib-stiffeners.", "Once it is passed through these rib-stiffeners, the outer skin is excited.", "There is dissipation in the energy that is transmitted to the outer skin for three reasons.", "Firstly, there is no direct connection between the source and the outer skin.", "Secondly, because of the vibration damping of the composite, and the fact that energy is dissipated over a distance, the larger the distance that the vibration travels, the lower the magnitude of the vibration.", "In this manner, the energy that is finally transmitted to the outer skin is significantly less, which will result in a quieter (and, as the case may be, stealthier) structure.", "Thirdly, because of the path that the internal vibrational motion must follow, there may be a tendency for conversion of interior longitudinal vibrational motion, which is difficult to dissipate to flexural vibrational motion, which is dissipated rather efficiently by composite materials.", "Moreover, the multi-layered, rib-stiffened composite cylinder assembly of the present invention provides for easier thermal management through the use of metallic inner skin with all other parts being composite;", "alternatively, composite materials such as graphite fibers in an epoxy could also be used for the inner skin for thermal management concerns.", "In this manner, the heat in the interior of the cylinder can be transmitted to a specific location on the cylinder or can be dissipated to appear to be of other shape than it actually is.", "This results because the composite is insulating in directions normal to the fiber direction and will not transmit the heat through it.", "All (or virtually all) of the heat can be made to exit at specific location(s).", "Additionally, the present invention features a material winding fabrication methodology which admits of continuous winding and layering.", "This invention thus provides an efficient fabrication method for making composite cylindrical sections in a continuous process.", "It should also be emphasized that the multiple wall construction of the present invention provides a damage-tolerant design.", "A notable feature of this invention is the multiplicity of layers having rib-stiffeners which are translatedly disposed in relation to the rib-stiffeners of each adjacent layer.", "The outer skin provides protection to the interior skins from shock or foreign object impact because direct structural connection is minimized;", "hence, significant catastrophic damage to the rest of the structure is minimized.", "Other objects, advantages and features of this invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.", "BRIEF DESCRIPTION OF THE DRAWINGS In order that the present invention may be clearly understood, it will now be described, by way of example, with reference to the accompanying drawings, wherein like numbers indicate the same or similar components, and wherein: FIG. 1 through FIG. 8 are schematic perspective views representing the steps of the fabrication methodology of the present invention.", "FIG. 9 is a diagrammatic axially transverse sectional view of the double-ribbed composite cylinder of this invention, taken along the plane of line 9--9 in FIG. 8. FIG. 10 is a diagrammatic partial perspective detail view of the mandrel and pin ring shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION Cylindrical workpiece 18, shown in various stages of completion in FIG. 1 through FIG. 8, is outward of and coaxial with mandrel 20.", "Referring now to FIG. 1, inner skin 22 is made of fibrous material.", "Unidirectional fibers are wound around cylindrical mandrel 20 to form a continuous skin, inner skin 22.", "Inner skin 22 of cylinder workpiece 18 has an outer surface defining a cylindrical shape which is coaxial with mandrel 20.", "As the term is used herein, a "fibrous"", "material is fiber, filament or tape of any appropriate material composition.", "In the context of circumferential winding, for most embodiments of the present invention the fibrous material has a width less than length 1 of completed cylinder 18, shown in FIG. 8;", "however, for some embodiments, the fibrous material which is circumferentially wound to form inner skin 22 or a subsequent continuous skin is a sheet-like material having a width commensurate with the longitudinal expanse of mandrel 20 and approximately equal to length 1 of completed cylinder workpiece 18.", "In the context of longitudinal winding, the width of the material being wound is generally normal to the longitudinal expanse of mandrel 20 as well as to the longitudinal expanse of the cylinder workpiece 18;", "here, a fibrous material has a width less than the circumference of the cylindrical shape along which the fibrous material is being wound.", "Hence, when the fibrous material is engaged with inner pins 30 and longitudinally wound along the cylindrical shape defined by the outer surfaces of inner circumferential ribs 24, as shown in FIG. 3, the fibrous material has a width less than the circumference of this cylindrical shape corresponding to inner circumferential ribs 24;", "similarly, when the fibrous material is engaged with outer pins 44 and longitudinally wound along the cylindrical shape defined by the outer surfaces of outer circumferential ribs 38, as shown in FIG. 7, the fibrous material has a width less than the circumference of this cylindrical shape corresponding to outer circumferential ribs 38.", "It is emphasized herein that any degree of commonality or differentiation between or among any of the material compositions actually used for the fibrous materials may be appropriate in accordance with a given embodiment of the present invention;", "hence, use herein, for example, of the terms "first"", "fibrous material, "second"", "fibrous material, and "third"", "fibrous material is not intended to suggest that the "first"", "fibrous material necessarily is either the same as or different from the "second"", "fibrous material, or that the "second"", "fibrous material necessarily is either the same as or different from the "third"", "fibrous material, or that the "first"", "fibrous material necessarily is either the same as or different from the "third"", "fibrous material.", "After inner skin 22 of appropriate thickness is wound, inner circumferential ribs 24 running circumferentially around inner skin 22 are wound, using a filament-winding or tape-laying machine.", "With reference to FIG. 2, a second fibrous material is wound circumferentially around the cylindrical shape defined by the outer surface of inner skin 22 so as to form a plurality of inner circumferential ribs 24 spaced apart axially and having equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20.", "FIG. 2 schematically illustrates inner circumferential ribs 24 wound over inner skin 22.", "Inner circumferential ribs 24 can be wound with or without the use of a dissolvable or sectional mold which is placed outside inner skin 22.", "If a dissolvable or sectional mold is utilized, this is removed after winding inner circumferential ribs 24.", "Referring to FIG. 3, two inner pin rings 26 are positioned, one at each axial end of mandrel 20.", "Each inner pin ring 26 has an inner ring 28 portion and a plurality of inner pins 30 spaced apart circumferentially and projecting radially from inner ring 28, as shown in FIG. 10.", "Each inner ring 28 has an outer surface defining a cylindrical shape which is coaxial with mandrel 20 and approximately equiradial with the cylindrical shape defined by said outer surfaces of inner circumferential ribs 24.", "A third fibrous material is engaged with inner pins 30 and wound longitudinally along the cylindrical shape defined by the outer surfaces of inner circumferential ribs 24 so as to form a plurality of inner longitudinal stringers 32 which are spaced apart circumferentially and correspondingly with inner pins 30 and have equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20.", "It is emphasized that the present invention provides a unique methodology of allowing for tape or fiber placement over inner circumferential ribs 24, thus succeeding in winding intermediate skin 36 on top of circumferential ribs 24.", "Intermediate skin 36 cannot merely be wound directly onto inner circumferential ribs 24, since a continuous surface does not exist onto which the tape or fibers can be positioned.", "The present invention accomplishes this with the use of two pin rings 26, one positioned at each end of the wound piece.", "Inner pin rings 26 have a small cylindrical section, inner rings 28, of diameter approximately equal to that of the wound part.", "A series of inner pins 30, for some embodiments preferably equally spaced apart, extend in the radial direction outward from inner rings 28.", "Fibers or tapes are wound along the axis of the cylinder at some spacing, for some embodiments preferably about 1 inch, depending on dimensions.", "As the tape or filament winding machine makes a pass along the axis of the cylinder, the mandrel rotates a specified angular amount and traverses again along the axis of the cylinder.", "Typically, in the absence of inner pin rings 26, such a fiber or tape position would not remain, since it is not a geodesic path;", "however, in accordance with this invention, inner pin rings 26 keep the fibers or tapes in their axial position.", "Reference now being made to FIG. 4, a fourth fibrous material is wound circumferentially around the cylindrical shape defined by the outer surfaces of inner longitudinal stringers 32 so as to form a pair of inner circumferential bands 34 , (only one of the pair shown in the figure), located longitudinally inward of and adjacent to inner pin rings 26, inner circumferential bands 34 being spaced apart longitudinally and having equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20.", "Tapes or fibers are wound in the hoop direction at the ends of cylinder workpiece 18 to form inner circumferential bands 34, which provide a net force on inner longitudinal stringers 32 in the radial direction toward the interior of the cylinder.", "Another continuous skin is wound over top inner longitudinal stringers 32 and inner circumferential bands 34, referring now to FIG. 5. Here, a fifth fibrous material is wound circumferentially around the cylindrical shape defined by the outer surfaces of inner longitudinal stringers 32 and inner circumferential bands 34 so as to form intermediate skin 36 having an outer surface defining a cylindrical shape which is coaxial with mandrel 20.", "At this point, referring to FIG. 5, cylinder workpiece 18 comprises inner skin 22, a plurality of inner circumferential ribs 24, a pair of inner pin rings 26, a plurality of inner longitudinal stringers 32, a pair of inner circumferential bands 34, and intermediate skin 36.", "In order to add another ribbed layer to cylinder workpiece 18, steps pertaining to circumferential winding of ribs, positioning of pin rings, longitudinal winding of longitudinal stringers, circumferential winding of bands, and circumferential winding of a skin, are essentially repeated.", "Referring to FIG. 6 and FIG. 9, a second set of ribs is wound over the skin, but with their positions displaced relative to the ribs located axially inward thereof.", "Here a sixth fibrous material is wound circumferentially around the cylindrical shape defined by the outer surface of intermediate skin 36 so as to form a plurality of outer circumferential ribs 38.", "Outer circumferential ribs 38 are spaced apart longitudinally and staggeringly with respect to inner circumferential ribs 24 and have equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20.", "The specific positions of outer circumferential ribs 38 in relation to inner circumferential ribs 24 may be selected in accordance with both acoustical and structural design considerations.", "Selection of numbers and material compositions of inner circumferential ribs 24 and outer circumferential ribs 38 may also be relevant to these design considerations.", "For some embodiments, placement of outer circumferential ribs 38 is preferably translatedly uniform in relation to placement of inner circumferential ribs 24.", "For other embodiments of this invention, outer circumferential bands 38 are positioned variably or randomly in relation to successive inner circumferential ribs 24;", "in some embodiments and applications variable or random rib translation may provide enhanced vibrational energy dissipation.", "Also, for many embodiments of this invention inner circumferential ribs 24 and outer circumferential ribs 38 preferably provide stiffening for the composite cylinder with a minimum of weight.", "Referring to FIG. 7, two outer pin rings 40 are positioned, one at each axial end of mandrel 20.", "Each outer pin ring 40 has an outer ring 42 portion and a plurality of outer pins 44 spaced apart circumferentially and projecting radially from outer ring 42, referring again to FIG. 10, which may be viewed as generally representative of the pin ring configuration in accordance with this invention.", "Each outer ring 42 has an outer surface defining a cylindrical shape which is coaxial with mandrel 20 and approximately equiradial with the cylindrical shape defined by said outer surfaces of outer circumferential ribs 38.", "A second set of longitudinal stringers is wound in place with the use of the pin ring assembly, again resulting in a cylinder workpiece 18 structure such as that shown in FIG. 7. Here, a seventh fibrous material is engaged with outer pins 44 and wound longitudinally along the cylindrical shape defined by the outer surfaces of outer circumferential ribs 38 so as to form a plurality of outer longitudinal stringers 46 which are spaced apart circumferentially and correspondingly with outer pins 44 and have equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20.", "It is emphasized that the pins for any of the pairs of pin rings in accordance with this invention may be relatively distantly spaced apart, or relatively closely spaced apart, for various embodiments of this invention;", "hence, the longitudinal stringers which engage a particular pair of pin rings will be correspondingly distantly or closely spaced apart, and may even be contiguous, with respect to each other.", "Therefore, for example, for some embodiments longitudinal stringers 30 form a continuous or substantially continuous surface if the spacings between pins 30 are sufficiently small and the band widths of longitudinal stringers 32 are sufficiently great;", "similarly, longitudinal stringers 46 form a continuous or substantially continuous surface if the spacings between pins 40 are sufficiently small and the band widths of longitudinal stringers 46 are sufficiently great.", "Reference again being made to FIG. 4, which may be viewed as generally representative of circumferential winding of circumferential bands in accordance with this invention, an eighth fibrous material is wound circumferentially around the cylindrical shape defined by the outer surfaces of outer longitudinal stringers 46 so as to form a pair of outer circumferential bands 48 located longitudinally inward of and adjacent to outer pin rings 40, outer circumferential bands 48 being spaced apart longitudinally and having equiradial outer surfaces defining a cylindrical shape which is coaxial with mandrel 20.", "Thus, tapes or fibers are again wound in the hoop direction at the ends of cylinder workpiece 18, this time to form outer circumferential bands 48, which provide a net force on outer longitudinal stringers 46 in the radial direction toward the interior of the cylinder.", "Another continuous skin is wound over top outer longitudinal stringers 46 and outer circumferential bands 48, now referring to FIG. 8, which shows the completion of cylinder workpiece 18 as a double-layered, translated rib-stiffened composite cylinder.", "Here, a ninth fibrous material is wound circumferentially around the cylindrical shape defined by the outer surfaces of outer longitudinal stringers 46 and outer circumferential bands 48 so as to form outer skin 50 having an outer surface defining a cylindrical shape which is coaxial with mandrel 20.", "Accordingly, in this example a translated double rib-stiffened composite cylinder having a hollow core has been fabricated.", "This composite cylinder comprises: inner skin 22;", "a plurality of inner circumferential ribs 24 located radially outwardly adjacent to inner skin 22 and spaced apart longitudinally;", "a pair of inner pin rings 26 located at the axial ends of composite cylinder workpiece 18, one inner pin ring 26 at each axial end, each inner pin ring 26 having an inner ring 28 portion and a plurality of inner pins 30 spaced apart circumferentially and projecting radially from inner ring 28;", "a plurality of inner longitudinal stringers 32 located radially outwardly adjacent to inner circumferential ribs 24, inner longitudinal stringers 32 engaged with inner pins 30 and spaced apart circumferentially and correspondingly with inner pins 30;", "a pair of inner circumferential bands 34 located radially outwardly adjacent to inner longitudinal stringers 32 and longitudinally inwardly adjacent to inner pin rings 26;", "intermediate skin 36 located radially outwardly adjacent to inner circumferential bands 34 and inner longitudinal stringers 32;", "a plurality of outer circumferential ribs 48 located radially outwardly adjacent to intermediate skin 36, outer circumferential ribs 48 spaced apart longitudinally and staggeringly with respect to inner circumferential ribs 24;", "a pair of outer pin rings 40 located at the axial ends of composite cylinder workpiece 18, one outer pin ring 40 at each axial end, each outer pin ring 40 having an outer ring 42 portion and a plurality of outer pins 44 spaced apart circumferentially and projecting radially from outer ring 42;", "a plurality of outer longitudinal stringers 46 located radially outwardly adjacent to outer circumferential ribs 38, outer longitudinal stringers 46 engaged with outer pins 44 and spaced apart circumferentially and correspondingly with outer pins 44;", "a pair of outer circumferential bands 48 located radially outwardly adjacent to outer longitudinal stringers 46 and longitudinally inwardly adjacent to outer pin rings 40;", "and outer skin 50 located radially outwardly adjacent to outer circumferential bands 48 and outer longitudinal stringers 46.", "It is reemphasized that the composite cylinder in accordance with the present invention is a translated multiple rib-stiffened composite cylinder having any plural number of ribbed layers.", "Hence, appropriate repetition of steps in accordance with this invention succeeds in conversion of the completed double-layered, translated rib-stiffened composite cylinder in the above example to a triple-layered cylinder, for example, which further comprises: a plurality of first additional outer circumferential ribs located radially outwardly adjacent to outer skin 50 and spaced apart longitudinally and staggeringly with respect to outer circumferential ribs;", "a pair of first additional outer pin rings located at the axial ends of cylinder workpiece 18, one first additional outer pin ring at each axial end, each first additional outer pin ring having a ring portion and a plurality of pins spaced apart circumferentially and projecting radially from the ring portion;", "a plurality of first additional outer longitudinal stringers located radially outwardly adjacent to the first additional outer circumferential ribs, the first additional outer longitudinal stringers engaged with the pins of the first additional outer pin rings and spaced apart circumferentially and correspondingly with the pins of the first additional outer pin rings;", "a pair of first additional outer bands located radially outwardly adjacent to the first additional outer longitudinal stringers and longitudinally inwardly adjacent to the first additional outer pin rings;", "and a first additional outer skin located radially outwardly adjacent to the first additional outer bands and the first additional outer longitudinal stringers.", "Accordingly, in order to add each succeeding ribbed layer to cylinder workpiece 18, steps pertaining to circumferential winding of ribs, positioning of pin rings, longitudinal winding of longitudinal stringers, circumferential winding of bands, and circumferential winding of a skin, are appropriately repeated in accordance with this invention.", "Each repetition of steps forms a next outer layer of the composite cylinder, each next outer layer being radially outward of the previous other layer, the previous outer layer being the radially outermost outer layer prior to repetition of these steps.", "The previous outer layer includes previous circumferential ribs, previous pin rings, previous longitudinal stringers, previous bands, and a previous outer skin;", "the next outer layer includes the next circumferential ribs, the next pin rings, the next longitudinal stringers, the next bands, and the next outer skin, the next circumferential ribs spaced apart longitudinally and staggeringly with respect to the previous circumferential ribs.", "Other embodiments of this invention will be apparent to those skilled in the art from a consideration of this specification or practice of the invention disclosed herein.", "Various omissions, modifications and changes to the principles described may be made by one skilled in the art without departing from the true scope and spirit of the invention which is indicated by the following claims." ]
RELATED APPLICATION This application is a division of application Ser. No. 563,778 filed Mar. 31, 1975, now abandoned. BACKGROUND OF THE INVENTION The prior art is replete with attempts to discover new anti-inflammatory drugs that are useful in the treatment of arthritis. Some of the more widely published results relate to the use of aspirin, indomethacin, penicillamine, hydrocortisone and dexamethasone. While all have demonstrated, to varying degrees, anti-inflammatory activity, they all exhibit undesirable side effects. Such undesirable side effects include, for some of these drugs, toxicity problems; the production of fatty liver problems; and the creation of Cushing Syndrome. For a further and more complete discussion see Bach, "Adverse Reactions of Antirheumatic Drugs", Int. J. Clin. Pharmacol 7 2/3 (1973) 198-205. Of even more importance, all of the above anti-inflammatory drugs produce gastrointestinal ulceration in experimental animals and in humans. Volume VII, p. 160, Side Effects of Drugs, (1971 Exerpta Media, Amsterdam); G. L. Bach, "Adverse Reactions of Antirheumatic Drugs", supra. Insofar as the state of the art is concerned, it is widely recognized that "it has not been possible to dissociate gastrointestinal toxicity from antiinflammatory activity." Side Effects of Drugs, supra at p. 100. It is therefore the principal objectives of my invention to provide anti-inflammatory drugs for use in treating arthritis in experimental animals which exhibit improved anti-inflammatory activities while at the same time providing drugs that are antiulcergenic and have acceptable levels of toxicity. SUMMARY OF THE INVENTION It has been quite unexpectedly determined that copper coordination compounds produced by reacting copper salts with the following classes of organic compounds produce products which when used in accordance with the following processes, exhibit excellent anti-inflammatory activity in animals, i.e., a warmblodded animal or mammalian subject, and which are anti-ulcer: 1. aromatic carboxylic acids or their alkaline earth salts; 2. heterocyclic carboxylic acids or their alkaline earth salts; 3. amino acids or their alkaline earth salts; 4. amines; and 5. suitably substituted steroids. It has been empirically determined that the copper coordination compounds disclosed herein not only demonstrate excellent anti-inflammatory activity but that they are anti-ulcer and may be utilized both as anti-inflammatory agents in the treatment of arthritis and in the treatment of gastrointestinal ulcers in animals. In the treatment of inflammation and/or ulcers, the compounds are administered orally or parentrally. The copper coordination compounds, being relatively insoluble in water, are administered by dissolving them in saline solution to which a suitable suspending agent has been added. In treating inflammation by subcutaneously injecting test animals with the copper coordination compound so prepared it has been found that excellent anti-inflammatory results, in the test models hereinafter described, may be obtained if the dosages administered comprise about 2.5-165 mg. per kilogram of body weight. In treating gastrointestinal ulcers by orally introducing into test animals the copper coordination compounds of this invention it has been found that excellent results, in the test models hereinafter described, are obtained if the dosages administered comprise about 2 to 125 mg. per kilogram of body weight. DETAILED DESCRIPTION OF THE INVENTION For the purpose of more fully understanding the present invention, a copper coordination compound is intended to mean a compound whose molecular structure contains one or more copper atoms bonded to one or more atoms of one or more molecules or ions by coordinate covalant bonds. The copper coordination compounds of the present invention are prepared by reacting copper salts, preferably cupric cxhloric or cupric acetate with a member of the following classes of organic compounds: 1. aromatic carboxylic acids or their alkaline earth salts; 2. heterocycline carboxylic acids or their alkaline earth salts; 3. amino acids or their alkaline earth salts; 4. amines; and 5. suitably substituted steroids. More specifically, it has been found that suitable compounds may be produced by reacting cupric chloride with the sodium salts of L & D tryptophan, anthranilic acid, 3,5-diisopropylsalicyclic acid, acetylsalicyclic acid, hydrocortisone-21-phosphate, dexamethasone-21-phosphate, salicyclic acid, 3-p-chlorophenyl-3,4,5,6,-tetrahydro-β-carboline-5-carboxylic acid, 3, 4, 5, 6-tetra-hydro-β-carboline-5-carboxylic acid, and 1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid; by reacting cupric chloride with 1-phenyl-5-aminotetrazole, ε aminocaproic acid, pyridine, a mixture of D and L-tryptophan, morpholine, and histamine; by reacting cupric chloride with the ammonium salt of hydrocortisone-21-hemisuccinic acid; by reacting cupric acetate with the sodium salts of 2[3(trifluoro-methyl)phenyl] aminonicotinic acid (sometimes referred to hereinafter as tpan), 1-carboxyisoquinoline, phenylcinchoninic acid, hydrocortisone-21-phosphate, and 4-n-butyl-1,2-diphenyl-3,5-pyrazolidinedione; by reacting cupric acetate with the ammonium salt of nicotinic acid; by reacting cupric acetate with D-pencillamine, 1-phenyl-5-aminotetrazole, D or L-aspartic acid, L-lysine, 2-carboxyindole; and by reacting cupric acetate with the potassium salt of 17-hydroxy-3-oxo-17α-pregn-4,6-diene-21 carboxylic acid. It is preferable to produce copper coordination solvates rather than anhydrous compounds as will be more fully appreciated by the following description. The compounds may be solvated with a lower alcohol (methanol or ethanol), acetone, pyridine, water or dimethyl sulfoxide. Following is a more detailed description of how the copper coordination compounds of the present invention may be prepared. Table V contains suggested structural formulae for some of my coordination compounds. Not all have been empirically determined. EXAMPLE 1: Bis-L-tryptophanato(O,N)copper(II),[Cu(II) (L-tryptophan) 2 ] L-tryptophan (5.0 g, 0.025 mol) was dissolved in 100 ml of H 2 O with a solution of NaOH (50%), filtered and back titrated if necessary with a solution of HCl (10%) until indicator paper showed the solution to be weakly basic. This solution was then dropped into 100 ml of H 2 O containing CuCl 2 dihydrate (3.3 g, 0.021 mol). After stirring for about one hour a precipitate formed and was collected by filtration. This blue precipitate was washed with H 2 O and diethylether, dried at 100° and 15 mm Hg overnight and weighted (4.7 g, 82% yield). A sample of this material on heating turned brown at 240° C. and finally decomposed at 260° C. Analysis Calcd. for C 22 H 22 N 4 O 4 Cu: C, 56.22; H, 4.72; N, 11.92. Found: C, 56.07; H, 4.89 and N, 12.16. EXAMPLE 2:BIS-D-tryptophanato(O,N)copper(II)[Cu(II)(D-tryptophan) 2 ]. This coordination compound was prepared as described for the L isomer (example 1) using 5.0 g, 0.021 mol of D-tryptophan. After collecting the precipitate by filtration, washing with H 2 O, diethylether and acetone (250 ml), the precipitate was dried overnight at 100° and 15 mm Hg and weighed (4.3 g, 75% yield). A sample of this material decomposed slowly on heating to 269° C. Analysis Cacld. for C 22 H 22 N 4 O 4 Cu: C, 56.22; H, 4.72; N, 11.92. Found: C, 56.10, H, 4.72 and N, 12.00. EXAMPLE 3: Bisanthranilato(O,N)copper(II),[Cu(II)(anthranilate) 2 ] The sodium salt of anthranilic acid (5 g 0.04 mol) was prepared as decribed in example 1 in 150 ml of H 2 O with 50% NaOH. This solution was dropped into 300 ml of a stirred aqueous solution of CuCl 2 dihydrate (2.5 g, 0.016 mol). The precipitate which formed was removed by filtration and washed with H 2 O and diethylether (5×50 ml). After drying overnight @120° C. and 15 mm Hg the material weighed 6.1 g, 99% yield. A sample of this greenishblue material decomposed on heating to 240° C. and continued to decompose on heating to 290° C. Analysis Calcd. for C 14 H 6 N 2 O 4 Cu: C, 50.07; H, 3.60; N, 8.35. Found: C, 50.07; H, 3.77; N, 8.42. EXAMPLE 4: Bis(3,5-diisopropylsalicylato(O,O)copper(II)[Cu(II) (3,5-dips) 2 ] A solution of the sodium salt of 3,5-diisopropylsalicyclic diissopropylsalicyclic acid (5 g, 0.023 mol) was prepared as described in example 1 and added to 300 ml of a stirred aqueous solution of CuCl 2 dihydrate (1.59 g, 0.0336 mol). A brown precipitate formed which when recrystallized from ether gave green crystals. These crystals were filtered and dried at 125° C. and 15 mm Hg for three hours. The resulting brown crystalline material melted with decomposition over the range of 142°-144° C. Analysis Calcd. for C 26 H 34 O 3 Cu: C, 61.70; H, 6.77. Found: C, 61.49; H, 6.83. EXAMPLE 5: Tetra(μ-acetylsalicylato)biscopper(II),[Cu(II) 2 (aspirinate) 4 ] The sodium salt of acetylsalicylic acid was prepared by dissolving acetylsalicylic acid (30 g, 0.165 mol) in 200 ml of H 2 O at 0° C. with 50% NaOH so that the pH did not go above 11.0 and rarely reached 11.0. This was done over a period of 45 to 60 minutes. The final pH of the solution was about 8.7. The CuCl 2 solution prepared by adding 56.5 g, 0.330 mol of CuCl 2 dihydrate to 500 ml of water, was added to a stirred solution of sodium acetylsalicylate during a period of 10 to 15 minutes. Following the completion of this addition the blue precipitate was collected by filtration; washed with H 2 O (500 ml×2), acetone (400 ml×2) and diethylether (300 ml) and left to dry on a filter funnel attached to a water aspirator. After two days the powder was dried at 50° C. for 6- 7 hours and weighed (31.3 g, 90.6% yield). Analysis calculated for C 36 H 28 O 16 Cu 2 : C, 51.25; H, 3.35; Found: C, 51.20; H, 3.51. EXAMPLE 6: [2[3(trifluoromethyl)phenyl]aminonicotinato] 2n -(aqua) n -copper (II) n ,[Cu(II) n (tpan) 2n (H 2 O) n ] The sodium salt of 2[3 (trifluoromethyl)phenyl] aminonicotinic acid (20 g, 0.0708 mol) was prepared as described in example 1. The solution of this salt was then added to about 300 ml of a saturated, stirred solution of cupric acetate monohydrate. The resultant greenish precipitate was collected by filtration and dissolved in 200 ml of diethylether. The ether solution was then dropped into about 4 liters of boiling skellysolve A. The resultant precipitate was collected from the hot solution by filtration, dried at 125° C. for three hours at 15 mm Hg and weighed (16 g, 70% yield). A sample of this material melted with decomposition over the range of 201° to 208° C. Analysis Calcd. for C 52 H 36 O 10 N 8 F 12 Cu: C, 48.49; H, 2.82; N, 8.70. Found: C, 48.53; H, 2.66; N, 8.91. EXAMPLE 7: D-penicillaminato-(aqua) 1 .5 -copper(I),[Cu(I) n (D-pen) n (H 2 O) 1 .5n ] D-penicillamine (5 g, 0.0335 mol) was dissolved in 50 ml of water. The solid cupric acetate monohydrate (6.68 g, 0.017 mol) was then added to the solution at such a rate so as to not exceed its rate of solution. Upon the completion of this addition the solution was dark gray. About 50-100 ml of H 2 O was then added and the mixture left to stir for about 30 minutes. The resultant gray precipitate was collected by filtration leaving a blue filtrate (125 ml). This blue filtrate was subsequently diluted with about 375 ml of acetone and set aside for use in example 8. The air-dried gray powder weighed 4.3 g, 54.0% yield. A sample of this material decomposed over the range of 155°-157° C. Analysis Calcd. for C 5 H 9 SNO 3 .5 Cu: C, 25.26; H, 5.10; N, 5.89. Found: C, 25.32; H, 5.03; N, 5.47. EXAMPLE 8: (D-penicillaminato) 2n -(aqua) 2n -copper(II),[Cu(II) n (D-pen) 2n (H 2 O) 2n ] On standing, the acetone diluted blue filtrate described in the preparation of Example 7 gave a gray precipitate which was collected by filtration and this filtrate also set aside. The gray solid was washed with 60 ml of water and the remaining light tan solid washed with 60 ml of acetone air dried and weighed (1.15 g, 17.4% yield). A sample of this solid melted with decomposition over the range of 155° to 157° C. Analysis Calcd. for C 10 H 24 O 6 N 2 Cu: C, 30.33; H, 6.11; N, 7.08. Found: C, 30.42; H, 6.49; N, 6.72. EXAMPLE 9: (D-pencillamine disulfide) n -(aqua) 3n copper(II) n ,[Cu(II) n (D-pen disulfide) n (H 2 O) 3n ] The acetone-water filtrate obtained after removing example 8 from the blue acetone filtrate, described above, was concentrated to about 100 ml and diluted with 400 ml of acetone. A blue precipitate (1.3 g, 9.4% yield) was obtained following filtration, washing with acetone and air drying. A sample of this material decomposed over the range of 157° to 158° C. After drying twice at 73° and 15 mm Hg overnight a sample of this material decomposed over the range of 173° to 175° C. Analysis Calcd. for C 10 H 24 N 2 S 2 O 7 Cu: C, 29.15; H, 5.87; N, 6.80. Found: C, 29.43; H, 5.76; N, 6.36. EXAMPLE 10: (Acetato) 2n -(1-phenyl-5-aminotetrazolato) n -copper(II) n ,[Cu(II) n (pat) n (acetate) 2n ] Five grams of cupric acetate monohydrate (0.012 mol) was dissolved in 20 ml of H 2 O. This solution was diluted with 100 ml of methanol. 5 g (0.31 mol) of 1-phenyl-5-aminotetrazole was added to obtain a blue gel. This gel was filtered and the resulting blue flakes were washed with about 400 ml of methanol until the washings were no longer blue. The filtrate was then concentrated to about 150 ml and stored for about one week in the refrigerator. A precipitate formed and was removed by filtration. This green crystalline solid was air dried and weighed (3.8 g, 17.9% yield). A sample of this solid decomposed over the range of 186°-189° C. Analysis Calcd. for C 22 H 26 N 10 O 8 Cu 2 : C, 38.54; H, 3.82; N, 20.43. Found: C, 38.42; H, 3.94; N, 20.92. EXAMPLE 11: (1-phenyl-5-aminotetrazolato) 2n -(chloride) 2n -copper(II) n ,[Cu(II) n (pat) 2n (HCl) 2n ] Five grams (0.012 mol) of 1-phenyl-5-aminotetrazole was dissolved in 30 ml of methanol, then 5 g (0.029 mol) of CuCl 2 dihydrate dissolved in 25 ml of methanol was added to the stirred solution of tetrazole. The resulting solution was filtered and set aside. Three subsequent crops of a green solid were obtained following filtration and concentration of the filtrate. The combination of these were air dried and weighed (5 g, 17.7% yield). A sample of this material decomposed on heating over the range of 184° to 185° C. Analysis Calcd. for C 14 H 14 N 10 CuCl 2 : C, 36.81; H, 3.09; N, 30.67. Found: C, 36.65; H, 3.17; N, 31.03. EXAMPLE 12: (D-Aspartato) n (aqua) 3 .5n -copper(II)) n ,[Cu(II) n (D-aspartate) n (H 2 O) 3 .5n ] This material is made in a manner similar to the preparation of example 1 using D-aspartic acid in place of L-tryptophan. Analysis calculated for C 4 H 12 N O 7 .5 Cu: C, 18.69; H, 4.66. Found: C, 18.55; H, 4.92. EXAMPLE 13: (L-Aspartato) n -(aqua) 3 .5n -copper(II) n ,[Cu(II) n (L-aspartate) n (H 2 O) 3 .5n ] This material is made in a manner similar to the preparation of example 1 using L-aspartic acid in place of L-tryptophan. Analysis calculated for C 4 H 12 N O 7 .5 Cu: C, 18.69; H, 4.66. Found: C, 18.41; H, 4.73. EXAMPLE 14: (L-Lysino) n -(chloro) 2n -(aqua) n -copper(II) n ,[Cu(II) n ,(L-lysinate) n (Cl) 2n (H 2 O) n ] This material is made in a manner similar to example 1 using L-lysine in place of L-tryptophan. A sample of this material decomposed on heating over the range of 169° to 170° C. Analysis calculated for C 6 H 16 N 2 O 3 CuCl 2 : C, 24.10; H, 5.40; Cl, 23.70; N, 9.38. Found: C, 24.54; H, 5.07; Cl, 24.00; N, 9.36. EXAMPLE 15: (L-Lysino) 2n -(chloro) 2n -(aqua) n -cooper(II) n ,[Cu(II) n (L-lysinate) 2n (Cl) 2n (H 2 O) n ] This material is made in a manner similar to example 1 using L-lysine in place of L-tryptophan. A sample of this compound decomposed on heating up to and over the range 210° to 214° C. Analysis calculated for C 12 H 32 N 4 O 5 CuCl 2 : C, 32.40; H, 6.80; Cl, 12.60. Found: C, 32.56; H, 7.04; Cl, 12.24. EXAMPLE 16: Bis(D,L-tryptophanato(O,N)copper(II),[Cu(II)(D,L-tryptophan) 2 ] This coordination compound was prepared and isolated as described in example 1 using a mixture of D and L-tryptophan in place of L-tryptophan. Analysis Calcd. for C 22 H 22 N 4 O 4 Cu: C, 56.22; H, 4.72. Found: C, 55.58; H, 4.87. EXAMPLE 17: (ε-aminocaproato) n -(chloro) 1 .5n -(methanol) 0 .5n -copper(II) n ,[Cu(II) n (ε-aminocaproate) n (Cl 1 .5n (CH 3 OH) 0 .5n ] This coordination compound was prepared by stirring a suspension of 10 g (0.08 mol) of ε-aminocaproic acid in 200 ml of methanol and slowly adding 10 g (0.065 mol) of solid cupric chloride dihydrate. The resultant green precipitate was collected by filtration washed with methanol, dried at 25° C. and 15 mm Hg overnight, and weighed (10.5 g, 51% yield). A sample of this material decomposed over the range of 157° to 158° C. Analysis Calcd. for C 7 H 15 .5 O 2 .5 CuCl 1 .5 : C, 29.53; H, 5.91; Cl, 20.11. Found: C, 29.97; H, 6.06; Cl, 20.36. EXAMPLE 18: (ε-aminocaproato) n -(chloro( 2n -(aqua) 0 .5n -copper(II) n ,[Cu(II) n (ε-aminocaproate) n (Cl) 2n (H 2 O) 0 .5n ] This coordination compound was obtained from the filtrate described in example 17. Following concentration of the filtrate and methanol washings to about 100 ml of bluish-green precipitate formed. This precipitate was collected by filtration dried at 25° C. at 15 mm Hg and weighed (4.6 g, 21% yield). A sample of this material decomposed on heating over the range of 193° to 194° C. Analysis Calcd. for C 6 H 14 NO 2 .5 Cl 2 Cu: C, 26.24; H, 5.14; Cl, 25.82. Found: C, 26.29; H, 5.28; Cl, 25.39. EXAMPLE 19: tetra(μ-acetato)bis(monopyridino)copper(II),[Cu(II) n (pyridine) n (acetate) 2n ] This coordination compound was prepared by adding 10 g (0.025 mol) of cupric acetate monohydrate to 70 ml of pyridine and the mixture heated while stirring at 100° C. The hot suspension was filtered and the resulting precipitate collected by filtration and washed with 200 to 300 ml of diethylether. A sample of this green solid decomposed on heating over the range of 214° to 216° C. When the ether-pyridine filtrate cooled a second precipitate, which was bluish, was obtained. Removal by filtration and washing with ether gave a second crop of the green material in the filtrate. This green solid had a decomposition range of 216° to 218° C. The mixture decomposition range of 216° to 218° C. was observed for a sample of the combination of the two green solids. Total yield was 12 g, 92%. Analysis Calcd. for C 18 H 22 N 2 O 8 Cu 2 : C, 41.46; H, 4.25; N, 5.37. Found: C, 41.87; H, 4.54; N, 5.23. EXAMPLE 20: Bispyridinobischlorocopper(II),[Cu(II)(pyridine) 2 (Cl) 2 ] This composition was prepared by dissolving 9.42 g (0.062 mol) of CuCl 2 dihydrate in 95% ethanol and adding 15 g (0.19 mol) of pyridine slowly to the stirred solution. The resultant blue precipitate was removed by filtration, washed with 95% ethanol (200 ml), dried at about 50° C. for 24 hours and weighed (19.8 g, 35.6% yield). A sample of this material decomposed over the range of 225° to 275° C. Analysis Calcd. for C 10 H 10 N 2 CuCl 2 : C, 41.32; H, 3.44. Found: C, 41.25; H, 3.52. EXAMPLE 21: Bismorpholoniumtetrachlorocopper(II),[Cu(II)(morpholine) 2 (Cl) 2 (HCL) 2 ] This coordination compound was prepared according to the published procedure of W. H. C. Rueggeberg, G. N. Jarman and R. B. Wearn, J.A.C.S., 69, 1222 (1947) incorporated by reference herein. Starting with 14.5 g (0.167 mol) of morpholine the coordination compound was obtained in 41% yield. A sample of this green crystalline melted with decomposition over the range of 167°-170° C. Analysis Calcd. for C 8 H 20 N 2 O 2 CuCl 4 : C, 25.17; H, 5.28; N, 7.34. Found: C, 25.17; H, 5.41; N, 7.21. EXAMPLE 22: (Histamino) n -(chloro) 2n -(hydrochloro) 2n -copper(II) n ,[Cu(II) n (histamine) n (Cl) 2n (HCl) 2n ] This coordination compound was prepared by mixing 5 g (0.048 mol) of cupric chloride dihydrate in 200 ml of methanol and concentrating to 135 ml. On standing a tan solid precipitated. This was removed by filtration and the filtrate concentrated to 80 ml. Upon addition of 40 ml of diethylether to this concentrate a light green solid precipitated. After removal by filtration and air drying this material was weighed (4.0 g, 23% yield). A sample decomposed over the range of 185° to 189° C. with softening at 182° C. Analysis Calcd. for C 5 H 10 N 3 Cl 4 Cu: C, 18.91; H, 3.17; N, 13.24. Found: C, 18.90, H, 3.30; N, 13.30. EXAMPLE 23: (Sodium) 4 -(salicylato) 4 -copper(II) 2 ,[Cu(II) 2 (salicylate) 4 (Na) 4 ] This material was prepared from the material obtained in example 24 with the addition of sodium ethoxide in suitable solvent. Analysis calculated for C 28 H 16 O 12 Cu 2 Na 4 were found to be within ±0.4% of the theoretical values. EXAMPLE 24: (Salicylato) 2n -(aqua) 4n -copper(II) n ,[Cu(II)(Salicylate) 2 (H 2 O) 4 ] This material may be prepared as described in example 1 using salicylic acid in place of L-tryptophan. Analysis calculated for C 14 H 18 O 10 Cu: C, 41.03; H, 4.43. Found: C, 41.24; H, 4.52. EXAMPLE 25: (Pyridine-3-carboxylato( 2n -(aqua) 1 .5n -copper(II),[Cu(II) 2n (nicotinate) 4n (H 2 O) 3n ] This coordination compound was prepared by dissolving 10 g (0.08 mol) nicotinic acid in 100 ml of water with concentrated NH 4 OH so that the final pH was 7.0. A cupric chloride solution, prepared by dissolving 21.6 g (0.14 mol) of cupric chloride dihydrate in 200 ml of water, was stirred while the ammonium salt of nicotinic acid was added dropwise. The blue precipitate was collected by filtration, washed with 500 ml of water and air dried. The resulting material was dried at 80° C. and weighed (10.7 g, 80% yield). A sample of this material decomposed on heating up to and through the range of 265° to 266° C. Analysis Calcd. for C 24 H 22 O 11 N 4 Cu 2 : C, 43.05; H, 3.31; N, 8.37. Found: C, 43.25; H, 3.00; N, 8.12. EXAMPLE 26: (Isoquinoline-1-carboxylato) 2n -copper(II) n ,[Cu(II) n (1-carboxyisoquinoline) 2n ] The copper coordination compound of 1-carboxyisoquinoline (5 g 0.029 mol) was prepared by adding to its solution of the sodium salt, prepared as in example 1 in 200 ml of water using 1-carboxyisoquinoline in place of L-tryptophan, 60 ml of a saturated aqueous solution of cupric acetate monohydrate. The resultant purple precipitate was collected by filtration, washed with 500 ml of water and dried overnight at 100° C. and 15 mm Hg. A sample of this material (4.0 g, 70.2% yield) decomposed over the range of 295° to 296° C. Analysis Calcd. for C 20 H 12 N 2 O 4 Cu: C, 58.84; H, 2.97; N, 6.87. Found: C, 58.49; H, 3.14; N, 6.79. EXAMPLE 27: (2-Phenyl-4-isoquinoline-carboxylato) 2n -(aqua) 2n -copper(II) n ,[Cu(II) n (2-phenyl-4-carboxyisoquinoline) 2n (H 2 O) 2n ] This coordination compound was synthesized from the sodium salt of phenylcinchoninic acid (25 g, 0.15 mol), which was prepared as described in example 1 using "2-phenyl-4-isoquinoline-carboxylic acid" in place of L-tryptophan in 550 ml of water. The solution of the sodium salt was dropped into a stirred solution of cupric chloride dihydrate (14.2 g, 0.09 mol). The resulting green precipitate was collected by filtration, washed with methanol, water and then air dried and weighed (29.5 g, 67% yield). A sample of this material decomposed on heating over the range of 228° to 229° C. Analysis Calcd. for C 64 H 48 N 4 O 12 Cu 2 : C, 64.48; H, 4.06; N, 4.70. Found: C, 64.55; H, 3.80; N, 4.61. EXAMPLE 28: (Indole-2-carboxylato) 3n -(acetato) n -aqua) 0 .5n,[Cu(II) n (2-carboxyindole) 3n (acetate) n (H 2 O) 0 .5n ] This copper coordination compound was prepared from the parent acid 2-carboxyindole (4.5 g, 0.028 mol) as in example 1, using cupric acetate. The green precipitate was collected by filtration, air dried for several days, suspended in boiling methanol and again collected by filtration. It was then dried at 100° C. and 15 mm Hg overnight and at 125° and 15 mm Hg for 3 hours. A sample of this material (3.0 g, 23.3% yield) decomposed over the range of 249°-255° C. Analysis Calcd. for C 29 H 22 N 3 O 9 Cu: C, 56.91; H, 3.59; N, 6.86. Found: C, 56.87; H, 4.03; N, 6.62. EXAMPLE 29: (Indole-2-carboxylato) 3n -(acetato) n -(aqua) 3 .5n,[Cu(II) n (2-carboxyindole) 3n (acetate) n (H 2 O) 0 .5n ] This material was prepared as described in example 1 using 2-carboxyindole in place of L-tryptophan and dried at 100° C. and 15 mm Hg over the weekend. A sample of this material did not melt but did turn brown, as did the material in example 28, on heating to 260°. Analysis Calcd. for C 29 H 28 N 3 O 12 Cu: C, 52.29; H, 4.20; N, 6.30. Found: C, 51.85; H, 3.78; N, 6.59. EXAMPLE 30: (3-p-chlorophenyl-3,4,5,6-tetrahydro-β-carboline-5-carboxylato) 2 n -(aqua) 2n -copper(II) n ,[Cu(II) n (cp-tcca) 2n (H 2 O) 2n ] The copper coordination compound of the parent acid (5 g, 0.015 mol) was prepared as described for example 1 except 3-p-chlorophenyl-3,4,5,6-tetrahydro-β-carboline-5-carboxylic acid was substituted for L-tryptophan. An olive drab precipitate was collected by filtration, washed with 500 ml of H 2 O, 300 ml of diethylether and then with acetone until the washings were colorless. This material was dried at 100° C. overnight and 110° C. at 15 mm Hg for 3 hours before dissolving in acetone and precipitated with Skellysolve B. This material (2 g, 40% yield) was then dried overnight at 60° C. and 15 mm Hg and again at 125° C. and 15 mm Hg. A sample of this material decomposed over the range of 205° to 210° C. Analysis Calcd. for C 36 H 32 Cl 2 N 4 O 6 Cu: C, 57.56; H, 4.30; N, 7.46. Found: C, 57.16; H, 4.15; N, 6.96. EXAMPLE 31: (3,4,5,6-Tetrahydro-β -carboline-5-carboxylato) 2n (aqua) 2 .5n -copper(II) n ,[Cu(II) n (tcca) 2n (H 2 O) 2 .5n ] The copper coordination compound of the parent acid (5 g, 0.023 mol) was prepared as described for example 1 except that 3,4,5,6-tetrahydro-β-carboline-5-carboxylic acid was substituted for L-tryptophan. This dark green solid was washed with 500 ml of water, then suspended in 500 ml of boiling acetone and collected by filtration. Drying was done at 100° C. at atmospheric pressure for 24 hours and then at 110° C. and 15 mm Hg for 3 hours. Subsequent leaching with hot propylene glycol gave an insoluble material (3.3 g, 52.8% yield) which rapidly decomposed on heating to 294° C. Analysis Calcd. for C 24 H 27 N 4 O 6 .5 Cu: C, 53.47; H, 5.05 and N, 10.40. Found: C, 53.54; H, 4.69 and N, 10.58. EXAMPLE 32: (Hydrocortisone-21-phosphato) 2n -(aqua) 9n -copper(II) 3n ,[Cu(II) 3n (HC-21-phosphate) 2n (H 2 O) 9n ] This coordination compound was prepared by dissolving 1 g (0.002 mol) of the disodium salt of hydrocortisone-21-phosphate in 25 ml of water and adding this solution dropwise to a stirred solution of cupric acetate monohydrate, prepared by adding 0.79 g (0.004 mol) of cupric acetate monohydrate to 25 ml of water. After the addition was complete, stirring was continued for one-half hour before the light blue precipitate was collected by filtration and washed with 500 ml of water before air drying. The yield was 0.185 g, 34%. On heating a sample of this material to 209° C. it decomposed. Analysis Calcd. for C 42 H 78 O 25 P 2 Cu 3 : C, 40.82; H, 6.36. Found: C, 40.59; H, 6.18. EXAMPLE 33: (Hydrocortisone-21-phosphato) 2n -(aqua) 7n -copper(II) 3n ,[Cu(II) 3n (HC-21-phosphate) 2n (H 2 O) 7n ] This coordination compound was prepared by dissolving 1 g (0.002 mol) of the disodium salt of hydrocortisone-21-phosphate in 100 ml of water, adding 1 drop of concentrated hydrochloric acid to give a pH of 6.6 and adding this solution dropwise to a stirred solution of cupric chloride dihydrate (1 g, 0.006 mol) in 50 ml of water. After the addition was complete the mixture was allowed to stir for one hour and the light blue precipitate collected by filtration, washed with 200 ml of water, air dried and weighed (400 mg, 33% yield). A sample of this material gradually decomposed on heating to 210° C. Analysis Calcd. for C 42 H 74 O 23 P 2 Cu 3 : C, 42.05; H, 6.22. Found: C, 42.00; H, 6.21. EXAMPLE 34: (Hydrocortisone-21-hemisuccinato) 4n -(aqua) 6n -copper(II) 2n ,[Cu(II) 2n (HC-21-hemisuccinate) 4n (H 2 O) 6n ] This coordination compound was prepared by dissolving 1 g (0.002 mol) of hydrocortisone-21-hemisuccinic acid in 250 ml of water with concentrated ammonium hydroxide. The resulting pH was 9.0 and was adjusted to pH 7.0 with a 10% solution of hydrochloric acid. This solution was then added dropwise to a stirred solution of cupric chloride dihydrate (1 g, 0.006 mol) dissolved in 250 ml of water. The resulting light blue-green precipitate was collected, air dried and weighed (1 g, 96% yield). A sample of this material decomposed on heating over the range of 191° to 195° C. Analysis Calcd. for C 100 H 144 O 38 Cu 2 : C, 57.71; H, 6.97. Found: C, 57.41; H, 7.26. EXAMPLE 35: (Hydrocortisone-21-hemisuccinato) 4n -(aqua) 7n -copper(II) 2 .5n [Cu(II) 2 .5n (HC-21-hemisuccinate) 2n (H 2 O) 7n ] This coordination compound was prepared by dissolving 1 g (0.002 mol) of hydrocortisone-21-hemisuccinic acid in 20 ml of water with concentrated ammonium hydroxide. The resulting pH was 9.5. This solution was then added dropwise to a stirred solution of cupric chloride dihydrate (1 g, 0.006 mol) dissolved in 15 ml of water. The light blue precipitate which formed was collected by filtration, air dried and weighed (1.2 g, 99% yield). A sample of this material decomposed on heating over the range of 196° to 197° C. Analysis Calcd. for C 100 H 160 O 46 Cu 5 : C, 49.71; H, 6.68. Found: C, 49.91; H, 6.63. EXAMPLE 36: (9α-Fluoro-11β, 17α, 21-trihydroxy-16α-methyl-1,4-pregnadiene-3,20-dione-21-phosphato).sub.2n -(aqua) 7n -copper(II) 3n ,[Cu(II) 3n (dexamethasone-21-phosphate) 2n (H 2 O) 7n ] This coordination compound was prepared by dropping a solution of the disodium salt of dexamethasone-21-phosphate (9 g, 0.017 mol) dissolved in 100 ml of water, into a stirred solution of 100 ml of water containing 4.6 g (0.003 mol) of cupric chloride dihydrate. After the addition was completed an additional 300 ml of water was added. The resulting light blue precipitate was collected by filtration, washed with water, air dried and weighed (8.1 g, 75% yield). A sample of this material gradually decomposed on heating to 300° C. Analysis Calcd. for C 88 H 140 O 46 P 4 F 4 Cu 6 : C, 42.02; H, 5.61. Found: C, 42.04; H, 5.5. EXAMPLE 37: (9α-Fluoro-11β, 17α-21-trihydroxy-16α-methyl-1,4-pregnadiene-3,20-dione-21-phosphato) 2n -(aqua) 1 .5n -copper(II) 3n ,[Cu(II) 3n (dexamethasone-21-phosphate) 2n (H 2 O) 1 .5n ] This coordination compound was prepared by taking 2 g (0.0008 mol) of the material prepared in example 36 and suspending it in a stirred methanol for two hours to remove some of the water of hydration. After air drying this material was dried at 45° C. and 15 mm Hg overnight. A sample of this material also decomposed on heating to 300° C. Analysis Calcd. for C 88 H 118 O 35 P 4 F 4 Cu 6 : C, 45.62; H, 5.13. Found: C, 45.51; H, 5.48. EXAMPLE 38: [1-(p-Chlorobenzoyl)-5-methoxy-2-methylindole-3- acetato] 4n -(aqua) 4n -copper(II) 2n ,Cu(II) 2n [1-p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetate] 4n (H 2 O) 4n ] This coordination compound was synthesized from the sodium salt of the parent acid (5 g, 0.014 mol), prepared as in example 1 except 1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid was used in place of L-tryptophan, in 200 ml of water. The solution of the sodium salt was dropped into a stirred 300 ml water solution of cupric chloride dihydrate (1.95 g, 0.013 mol). The resultant green precipitate was collected by filtration, washed with water, air dried and weighed (5.6 g, 98% yield). A sample of this material decomposed on heating to 190° C. Analysis Calcd. for C 76 H 68 O 20 N 4 Cl 4 Cu 2 : C, 56.13; H, 4.21; N, 3.44. Found: C, 56.00; H, 3.78; N, 3.40. EXAMPLE 39: [1-(p-Chlorobenzoyl)-5-methoxy-2-methylindole-3-acetato] 4n -(acetone) 2n -copper(II) 2n , Cu(II) 2n (1-p-chlorobenzoyl)-5-methoxy-3-methylindole-3-acetate] 4n (CH 3 COCH 3 ) 2n ] This coordination was prepared in a manner similar to that described for example 38, using twice the amount of parent acid and cupric chloride dihydrate. However, after the green precipitate was collected by filtration it was leached with 1 liter of acetone and the leachate concentrated to 500 ml. On standing, additional green crystals formed in the acetone solution. These were collected by filtration, air dried and weighed (6.9 g, 62% yield). A sample of this material decomposed on heating up to and over the range of 190° to 193° C. Analysis Calcd. for C 82 H 72 O 18 N 4 Cl 4 Cu 2 : C, 58.81; H, 4.79; N, 3.21. Found: C, 58.96; H, 4.34; N, 3.35. EXAMPLE 40: (4-n-Butyl-1,2-diphenyl-3,5-pyrazolidinedione) 2n -copper(II) n ,[Cu(II) n (4-n-butyl-1,2-diphenyl-3,5-pyrazolidinedione) 2n ] A solution of the sodium salt of the parent compound 4-n-butyl-1,2-diphenyl-3,5-pyrazolidinedione, (5 g, 0.015 mol) dissolved in 50 ml of 95% ethanol was diluted with 150 ml of H 2 O. To this stirred solution was added 2.73 g (0.007 mol) of cupric acetate monohydrate, in small aliquats. The greenish precipitate which formed was collected by filtration, dried at 95° C. and 15 mm Hg overnight and weighed (4.5 g, 94.5% yield). A sample of this material softened and melted over the range of 65° to 75° C. Analysis Caldcd. for C 38 H 38 N 4 O 4 Cu: C, 67.29; H, 5.65; N, 8.26. Found: C, 67.61; H, 5.43; N, 8.28. EXAMPLE 41: (17-Hydroxy-3-oxo-17α-pregn-4,6-diene-21-carboxalato) 2n -(aqua) 2n -copper(II) n ,[Cu(II) n (17-hydroxy-3-oxo-17α-pregn-4,6-diene-21-carboxylato) 2n (H 2 O) 2n ] The potassium salt of the parent acid (17-hydroxy-3-oxo-17α-pregn-4,6-diene-21-carboxylic acid) (5 g, 0.013 mol) was dissolved in 50 ml of water. This solution was dropped into a stirred solution of cupric acetate monohydrate, prepared by dissolving 5 g (0.012 mol) in 50 ml of water. After the addition was completed the mixture was left to stir for an additional one-half hour before removing the precipitate by filtration. This precipitate was washed with 500 ml of water before air drying followed by drying at 30° and 15 mm Hg over the weekend. A 5 g, 24% yield was obtained. A sample of this material decomposed on heating over the range of 168°-169° C. This material was redried at 40° and 15 mm Hg before obtaining elemental analysis. Analysis Calcd. for C 88 H 128 O 22 Cu 2 : C, 64.88; H, 7.67. Found: C, 64.44; H, 7.87. Inflammation Test Models Employed In order to test the anti-inflammatory activities of my copper coordination compounds, the following test models were employed: (1) Carrageenin Foot Edema Model as described in Experentia, 6, pp. 469-71, "Zur Frage des Mechanis Mos der Hemmung des Bindegebswachstums durch Cortisone" (1950); (2) Cotton Wad Granuloma Model as described in J. Pharmacol. Expt'l. Ther., 141, pp. 369-76, "Anti-inflammatory and Antipyretic Activities of Indomethacin, 9-(p-chlorobenzoyl)-5-Methoxy-2-Methyl-Indole-3-Acetic Acid" (1963); and (3) Polyarthritis Model as described in Nature, 224, pp. 1320-21, "Effect of Prostaglandin E 2 on Adjuvant Arthritis" (1969). The foregoing literature references were followed in the following tests unless otherwise stated and they are incorporated by reference herein. Each test model will only be briefly described. Each test model is a recognized and accepted model for testing drugs for the treatment of arthritis. Carrageenin Foot Edema Model In this test model test rats were injected with carageenin in a hind paw one hour after administration of the copper coordination compound. The carrageenin induced inflammation. The rats were male, of the Sprague Dawley variety and weighed on the average 120 grams. The copper coordination compounds were first introduced subcutaneously. The dosages were compounded as follows: TABLE A______________________________________Copper CoordinationCompoundWeight in Milligrams Saline Solution Suspending Agent______________________________________0.5 0.2 ml several drops1 0.2 ml per 10 ml2 0.2 ml5 0.2 ml25 0.2 ml______________________________________ The suspending agent was Tween 80, a nonionic surfactant sold by the Atlas Powder Company. A full description of it is contained at p. 648 of Remingtons Practice of Pharmacy (11th ed., Martin & Cook, The Mack Publishing Co., Easton Pa. 1956). Generally they may be described as a complex mixture of polyoxyethylene ethers of mixed oleic esters of sorbitol anhydrides. The initial screening dosage was 25 mg of the copper coordination compound given in one injection to ten rats. Compounds which were active received further testing at 5.0 mg and lower dosages. Each dosage was administered to at least ten rats. A dose was rated active if it caused a significant decrease (P<0.05) in the circumference of the feet injected with carrageenin six hours after administration. Compounds were rated active if they possessed a subcutaneous potency of ≧1%. As a reference standard, saline solution plus suspending agent was subcutaneously administered to each of the ten rats. Cotton Wad Granuloma This test utilizes the discovery that when cotton is introduced subcutaneously into a rat's skin it becomes encapsulated with connective tissue forming a granuloma. This is a manifestation of a local inflammatory response. The rats utilized were male, of the Sprague Dawley variety and weighed on the average 175-200 gm. The rats were given an adrenalectomy one day prior to implantation. The cotton pellets, sterilized, each weighing 32-50 mg but for each experiment not varying ±1 mg. were inserted in each animal adjacent to the abdomen. The copper coordination compounds were subcutaneously introduced in various dosages daily for two days. The dosages were prepared in accordance with Table A and the description given in explanation thereof. Each dose was administered to at least ten rats. The initial screening dose was 20 mg. The compounds were rated active if they caused a significant decrease (P<0.05) in the adjusted weight of the granuloma tissue encapsulating the implanted cotton. In order to arrive at the adjusted weight a reference standard, hydrocortisone, 0.5 mg. was administered subcutaneously to ten reference standard rats. After two days, the rats, in the test model and reference standard were sacrificed and the granulomas from each were removed, weighed, dried and reweighed. The adjusted weights were calculated as wet granuloma from test model compared to wet granuloma from reference standard and dry granuloma from test model compared to dry granuloma from reference standard. Polyarthritis Model In this model the test rats, male Sprague Dawley rats, 160-180 g, were inoculated intradermally at the base of the tail with a Freund type adjuvant as described in Nature, supra, to wit: 0.6 mg dry, heat-killed Mycobacterium butyricum (purchased from Difco) suspended in 0.05 ml of paraffin oil. The test rats were injected subcutaneously daily for 16 days with varying dosages of copper coordination compound prepared by mixing the copper compound with saline solution and suspending agent in the proportion set forth in Table A and in the manner described in connection therewith. The initial screening dose was 5 mg. Each dose was administered to at least twelve rats. As a control group, twelve rats were also injected subcutaneously with saline solution plus suspending agent. On day 16 (day 1=day of inoculation) the rats were sacrificed. The circumference of the tibiotarsal (ankle) joint was used as a measure of the severity of the inflammation. Table I and Table IV set forth the results of the foregoing tests and Table I includes in addition comparisons of the anti-inflammatory activities of my compound vs. hydrocortisone. Ulcer Test Models Employed To determine the ulcergenicity of my copper coordination compounds, two different test models were employed--the Shay rat test and the Corticoid Induced Rat Ulcer Test. These are commonly employed tests described in the literature. Shay, et al, "A Simple Method for the Uniform Production of Gastric Ulceration in the Rat," Gastroenterology 5, 43-61(1945); and Robert, A. et al., Proc. Soc. Expt'l. Biol. 99, pp. 443-47, "Ulcergenic Properties of Steroids" (1958), incorporated by reference herein. Shay Rat Test The procedure set forth in the above described method by Shay et al was followed. The rats were males of the Sprague Dawley variety, weighing 200-250 grams, which had been fasted for 72 hours. The control group of twelve rats received a saline and Tween 80 solution introduced intragastrically. An initial screening dose of 50 mg copper coordination compound, mixed with saline solution and Tween 80 suspending agent was introduced intragastrically into twelve rats. If the compounds displayed activity, as determined in the manner described below, dosages of either 0.5 mg, 1 mg, 2.5 mg, or 10 mg were administered. Each dose was given to at least twelve rats. The following Table B shows how the dosages were formulated. TABLE B______________________________________ Saline SolutionCopper Compound (mg) ML Suspending Agent______________________________________0.5 1 1 drop1 1 1 drop2.5 1 1 drop10 1 1 drop50 1 1 drop______________________________________ The activity of the dosages was arrived at by sacrificing the rats after 19 hours and determining the size and number of ulcers present. The incidence of ulcers in rats receiving the dosages of copper compounds were compared with the incidence of ulcers in rats in the control group. The compounds were rated active if the comparison showed that the compound significantly inhibited ulceration (P<0.05). Corticoid-Induced Rat Ulcer Test 8 mg of Δ 1 -cortisol in about 0.2 ml corn oil was injected subcutaneously into each rat in two groups of male Sprague Dawley rats (about 150 to 165 g) daily for four days. The rats in the control group received no other compound, while the rats in the treated group received orally 25 mg of various copper coordination compounds of my invention (1 ml saline solution - 1 drop Tween 80) three times daily. The results of this test, using the ulcer index as found in Robert, A. et al, Proc. Soc. Expt'l. Biol. 99, pp. 443-47, "Ulcergenic Property of Steroids" (1958) (incorporated by reference herein) are included in Tables III and IV. In addition to the foregoing anti-inflammatory and anti-ulcer tests, several LD 50 tests [performed in accordance with Miller et al, Proceed. of The Society of Expt'l. Medicine, 57, p. 261 (1944)] were performed with some copper coordination compounds and compared to cupric acetate, aspirin and tpan. The results are set forth in Table II along with TI data which is the ratio of the lethal dose to effective dose. The following surprising results may be gleaned quickly by reviewing the results set forth in Tables I-IV. (1) A marked increase in anti-inflammatory activity was observed for most of the compounds of the present invention as compared to prior art compounds. (2) Many parent compounds used to prepare the copper coordination compounds possess no anti-inflammatory activity while their copper coordination compounds did. (3) The LD 50 of the copper coordination compounds of my invention were substantially less than prior art anti-inflammatory agents. (4) While all known prior art compounds useful as anti-inflammatory agents are known ulcergenic componds, my copper coordination compounds displayed anti-ulcer activity. Upon further and more extensive study of the results the following observations are of interest to those skilled in the art. From a review of the Tables it can be noted that activity in the various test models is apparently not a function of the amount of the percent of copper present in the copper coordination compound. For example, activity in the Shay Rat Anti-Ulcer activity model was displayed in compounds at similar dosages having about 7.7% be weight copper and in compounds having about 19% by weight copper. While examples 1, 8, 16, 30 and 41 showed no anti-inflammatory activity at the initial screening tests and using only one test model, it is believed that they would display anti-inflammatory activity under other conditions. From the foregoing description it can be noted that all of the compounds of the present invention have the formula Cu y X n wherein y and n are numerals and wherein x is derived from at least one group of coordinating elements. By group of coordinating elements I mean a group of elements which are not attached to each other in a cyclic manner. The coordinating compounds may contain within them carbocyclic or heterocyclic structural components. By coordinating elements I mean elements which contribute electrons to form a covalent bond with copper, which may have a valence state of +1 or +2. In most instances, such coordinating elements are selected from the group of oxygen, nitrogen, halogen and sulfur. In most instances my copper coordination compounds have the formula Cu 1y X 2n . In this case the coordinating groups may be the same or different. Another class of my copper coordination compounds has the formula Cu 3y X 2n and the coordinating groups may be the same or different. A still further class has the formula Cu 2y X 4n and the coordinating groups may be the same or different. From the foregoing description it will also be understood that in the treatment of inflammation (arthritis) and gastrointestinal ulcers in animals my compounds may be administered in customary ways. While the dosages recommended herein for use are preferred, other dosages may also provide beneficial results. Referring now to Table V, which sets out some of the structural formulae of my copper coordination compounds, the following is given in explanation thereof. Example 1 has the structure d when the ligand is derived from L-tryptophan (a) and x is a amino. Example 2 has the structure d when the ligand is derived from D-tryptophan (a) and x is amino. Example 16 has the structure d when the ligand is derived from D,L-tryptophan (a) and x is amino. Example 3 has the structure d when the ligand is derived from anthranilic acid (b) and x is o-amino. Example 4 has the structure d when the ligand is derived from 3,5-diisopropylsalicyclic acid (c) and x is o-hydroxyl. TABLE I__________________________________________________________________________THE ANTI-INFLAMMATORY ACTIVITIES OF SOME COPPER COORDINATIONCOMPOUNDS COMPARED WITH SOME OF THEIR PARENT COMPOUNDS CARRA- % POTENCY GEENIN COMPAREDEX- FOOT COTTON WAD WITH HYDRO- %AMPLECOMPOUND EDEMA GRANULOMA POLYARTHRITIS CORTISONE COPPER__________________________________________________________________________cupric acetate A@1 mg SC I@20 mg SC I@5 mg SC 340 31.8L-tryptophan I@25 mg SC NT NT1 Cu(II)(L-tryptophan).sub.2 I@25 mg SC I@20 mg SC NT 13.5D-tryptophan I@25 mg SC NT NT2 Cu(II)(D-tryptophan).sub.2 A@25 mg SC I@20 mg SC NT 13.5anthranilic acid I@25 mg SC NT I@5 mg SC3 Cu(II)(anthranilate).sub. 2 A@1 mg SC A@5 mg SC [email protected] mg SC(+25) 60 18.93,5-dips acid I@25 mg SC NT I@5 mg SC4 Cu(II)(3,5-dips).sub. 2 A@1 mg SC A@1 mg SC [email protected] mg SC(+24) 50 12.5aspirin A@8 mg SC A@40 mg IG A@1 mg SC(+5) 65 Cu(II).sub.2 (aspirinate).sub.4 A@1 mg SC A@2 mg SC [email protected] mg SC(+27) 130 15.0tpan A@5 mg IG A@5 mg IG A@1 mg IG(+5) 316 Cu(II).sub.n (tpan).sub.2n (H.sub.2 O).sub.n A@1 mg SC A@2 mg SC [email protected] mg SC(+18) 180 10.1D-penicillamine I@25 mg SC I@20 mg SC I@5 mg SC7 Cu(I).sub.n D-pen(H.sub.2 O).sub.1.5n A@1 mg SC A@2 mg SC NT 26.78 Cu(II).sub.n (D-pen).sub.2n (H.sub.2 O).sub.2n I@25 mg SC NT NT 16.19 Cu(II).sub.n (D-pen disulfide).sub.n (H.sub.2 O).sub.3n A@1 mg SC A@5 mg SC A@5 mg SC(+18) 15.4pat I@25 mg SC A@20 mg IG A@20 mg IG(+5)10 Cu(II).sub.n (pat).sub.n (acetate).sub.2n A@1 mg SC A@5 mg SC A@5 mg SC(+5) 18.511 Cu(II).sub.n (pat).sub.2n (HCl).sub. 2n A@2 mg SC A@2 mg SC NT 13.9__________________________________________________________________________ TABLE II______________________________________THE LD.sub.50 AND CALCULATED TI DATAFOR SOME COPPER COORDINATION COMPOUNDSEX- TIAMPLE COMPOUND LD.sub.50 CFE PA______________________________________ cupric acetate 350 mpk SC 70 03 Cu(II)(anthranilate).sub. 2 750 ± 106 mpk 150 750 SC4 Cu(II)(3,5-dips).sub. 2 240 ± 33 mpk 48 240 SC aspirin 1500 mpk IG 790 mpk RT5 Cu(II).sub.2 (aspirinate).sub.4 760 ± 100 mpk 150 760 SC tpan 370 ± 25 mpk 15 74 IG6 Cu(II).sub.n (tpan).sub.2n (H.sub.2 O).sub.n 650 ± 80 mpk 130 650 SC______________________________________ TABLE III__________________________________________________________________________A COMPARISON OF THE ANTI-ULCER ACTIVITIES AMONG THECOPPER COORDINATION COMPOUNDS OFTABLE I AND SOME OF THEIR PARENT COMPOUNDS SHAY RAT: CORTICOID INDUCED: ANTI-ULCER ANTI-ULCEREXAMPLE COMPOUND ACTIVITY ACTIVITY__________________________________________________________________________ Cu(II).sub.2 (acetate).sub.4 (H.sub.2 O).sub.2 A@50 mg IG NT1 Cu(II)(L-tryptophan).sub. 2 [email protected] mg IG A@25 mg IG2 (Cu(II)(D-tryptophan).sub.2 A@1 mg IG NT D-tryptophan I@50 mg IG NT3 Cu(II)(anthranilate).sub.2 A@1 mg IG A@25 mg IG anthranilic acid A@50 mg IG NT4 Cu(II)(3,5-dips).sub. 2 [email protected] mg IG A@25 mg IG5 Cu(II).sub.2 (aspirinate).sub.4 [email protected] mg IG NT aspirin A@50 mg IG NT6 Cu(II).sub.n (tpan).sub.2n (H.sub.2 O).sub.n A@1 mg IG NT tpan I@50 mg IG NT7 Cu(I).sub.n D-pen(H.sub.2 O).sub.1.5n NT NT8 Cu(II).sub.n (D-pen).sub.2n (H.sub.2 0).sub.2n A@1 mg IG NT9 Cu(II).sub.n (D-pen disulfide).sub.n (H.sub.2 O).sub.3n A@1 mg IG NT10 Cu(II).sub.n (pat).sub.n (acetate).sub.2n A@1 mg IG NT11 Cu(II).sub.n (pat).sub.2n (HCl).sub.2n A@1 mg IG NT__________________________________________________________________________ TABLE IV__________________________________________________________________________THE ANTI-INFLAMMATORY AND ANTI-ULCER ACTIVITIES OF SOME ADDITIONAL COPPERCOORDINATIONCOMPOUNDS COMPARED TO SOME OF THEIR PARENT COMPOUNDS Shay Rat: Carrageenin Cotton Wad Percent Anti-UlcerEx. Compound Foot Edema Granuloma Polyarthritis Copper Activity__________________________________________________________________________ Amino Acids Cu(II).sub.n (D-aspartate).sub.n (H.sub.2 O).sub.3.5n A@1 mg SC A@2 mg SC NT 32.6 [email protected] mg IG Cu(II).sub.n (L-aspartate).sub.n (H.sub. 2 O).sub.3.5n A@1 mg SC NT NT 32.6 [email protected] mg IG Cu(II).sub.n (L-lysinate).sub.n (Cl).sub.2n (H.sub.2 O).sub.n [email protected] mg SC A@2 mg SC NT 21.9 A@10 mg IG Cu(II).sub.n (L-lysinate).sub.2n (Cl).sub.2n (H.sub.2 O).sub.n A@1 mg SC NT NT 14.3 NT16 Cu(II)(D,L-tryptophan).sub. 2 I@25 mg SC NT NT 13.5 A@1 mg IG17 Cu(II).sub.n (ε-aminocaproate).sub.n (Cl).sub.1.5n (CH.sub.3 OG).sub.0.5n NT NT NT 24.0 [email protected] mg IG18 Cu(II).sub.n (ε-aminocaproate).sub.n (Cl).sub.2n (H.sub.2 O).sub.0.5n NT NT NT 23.2 A@1 mg IG* Amines19 Cu(II).sub.2 (pyridine).sub.2 (acetate).sub.4 A@2 mg SC NT NT 24.4 [email protected] mg IG20 Cu(II) (pyridine).sub.2 (Cl).sub.2 A@1 mg SC NT NT 21.6 A@10 mg IG21 Cu(II)(morpholine).sub.2 (Cl.sub.2) (HCl).sub.2 [email protected] mg SC A@5 mg SC NT 16.6 NT22 Cu(II).sub.n (histamine).sub.n (Cl).sub.2n (HCl).sub.2n NT NT NT 20.0 A@ 10 mg IG* Salicylates Cu(II).sub.2 (salicylate).sub.4 (Na).sub.4 A@2 mg SC A@2 mg SC NT 17.8 NT Cu(II).sub.n (salicylate).sub.2n (H.sub.2 O).sub.4n A@1 mg SC A@5 mg SC NT 15.5 A@1 mg IG Heterocyclic Carboxylic Acids25 Cu(II).sub.2n (nicotinate).sub.4n (H.sub.2 O).sub.3n NT NT NT 19.0 A@1 mg IG26 Cu(II).sub.n (1-carboxyisoquinoline).sub.2n A@5 mg SC A@5 mg SC NT 15.6 A@50 mg IG27 Cu(II).sub.n (2-phenyl-4-carboxyisoquinoline).sub.2n (H.sub.2 O).sub.2n . NT NT NT 10.6 A@1 mg IG*28 Cu(II).sub.n (2-carboxyindole).sub.3n (acetate).sub.n (H.sub.2 O).sub.0.5n A@1 mg SC A@2 mg SC NT 16.5 [email protected] mg IG29 Cu(II).sub.n (2-carboxyindole).sub.3n (acetate).sub.n (H.sub.2 O).sub.3.5n NT NT NT 15.4 A@1 mg IG*30 Cu(II).sub.n (cp-tcca).sub.2n (H.sub.2 0).sub.2n I@25 mg SC NT NT 8.8 A@1 mg IG31 Cu(II).sub.n (tcca).sub.2n (H.sub.2 O).sub.2.5n I@5 mg SC NT NT 11.8 A@50 mg IG Corticoids hydrocortisone-21-phosphate(Na).sub.2 NT NT I@1 mg SC** I@10 mg IG**32 Cu(II).sub.3n (HC-21-phosphate).sub.2n (H.sub.2 O).sub.9n A@2 mg SC A@5 mg SC A@1 mg SC 15.4 A@5 mg IG (+7)**33 Cu(II).sub.3n (HC-21-phosphate).sub.2n (H.sub.2 0).sub.7n NT NT I@1 mg SC** 15.9 [email protected] mg IG hydrocortisone-21-hemisuccinate NT NT A@1 mg SC I@10 mg IG** (+7)**34 Cu(II).sub.2n (HC-21-hemisuccinate).sub.4n (H.sub.2 0).sub.6n [Green] A@2 mg SC A@5 mg SC A@1 mg SC 6.1 A@5 mg IG (+7)**35 Cu(II).sub.2.5n (HC-21-hemisuccinate).sub.2n (H.sub.2 O).sub.7n A@2 mg SC A@1 mg SC A@1 mg SC 13.5 A@10 mg IG* (+11)** Dexamethasone-21-phosphate(Na).sub.2 NT NT NT NT36 Cu(II).sub.3n (dexamethasone-21-phosphate).sub.2n (H.sub.2 O).sub.7n NT NT NT 15 A@5 mg IG37 Cu(II).sub.3n (dexamethasone-21-phosphate).sub.2n (H.sub.2 O).sub.1.5n NT NT NT 16 A@5 mg IG Arylacetic Acids38 Cu(II).sub.2n [1-(p-chlorobenzoyl)-5-methoxy-2- methylindole-3-acetate].sub.4n (H.sub.2 O).sub.4n NT NT NT 7.8 A@10 mg IG*39 Cu(II).sub.2n [1-(p-chlorobenzoyl)-5-methoxy-2- methylindole-3-acetate].sub.4n (CH.sub.3 COCH.sub.3).sub.2n NT NT NT 7.7 A@1 mg IG Pyrazolidinedione40 Cu(II).sub.n (4-n-butyl-1,2-diphenyl-3,5- pyrazolidinedione).sub.2n NT NT NT 11.8 A@10 mg IG Steroidal Acids41 Cu(II).sub.n (17-hydroxy-3-oxo-17 -pregn-4,6-diene-21- carboxalate).sub.2n (H.sub.2 O).sub.2n I@5 mg SC** NT I@5 mg SC** 7.8 A@5 mg__________________________________________________________________________ IG *Not tested at lower dose **Only dose tested NT = Not Tested TABLE V______________________________________ ##STR1## a ##STR2## b ##STR3## c ##STR4## dEXAMPLES 1, 2, 16; 3 and 4. ##STR5## EXAMPLE 5 ##STR6## EXAMPLE 19 ##STR7## EXAMPLE 20 ##STR8## EXAMPLE 21 ##STR9## EXAMPLE 23 ##STR10## EXAMPLE 24______________________________________
Disclosed herein are anti-inflammatory and anti-ulcer copper coordination compounds and a process for using them in the treatment of arthritis and gastrointestinal ulcers in animal bodies. The copper coordination compounds utilized are the reaction products of copper salts with: 1. aromatic carboxylic acids or their alkaline earth salts; 2. heterocyclic carboxylic acids or their alkaline earth salts; 3. amino acids or their alkaline earth salts; 4. amines; and 5. suitably substituted steroids. The process disclosed comprises administering to experimental animals, orally or parentrally (subcutaneously), in controlled dosages, the aforementioned copper coordination compounds for the treatment of inflammation (i.e., arthritis) and ulcers of the gastrointestinal tract.
Identify and summarize the most critical features from the given passage.
[ "RELATED APPLICATION This application is a division of application Ser.", "No. 563,778 filed Mar. 31, 1975, now abandoned.", "BACKGROUND OF THE INVENTION The prior art is replete with attempts to discover new anti-inflammatory drugs that are useful in the treatment of arthritis.", "Some of the more widely published results relate to the use of aspirin, indomethacin, penicillamine, hydrocortisone and dexamethasone.", "While all have demonstrated, to varying degrees, anti-inflammatory activity, they all exhibit undesirable side effects.", "Such undesirable side effects include, for some of these drugs, toxicity problems;", "the production of fatty liver problems;", "and the creation of Cushing Syndrome.", "For a further and more complete discussion see Bach, "Adverse Reactions of Antirheumatic Drugs", Int.", "J. Clin.", "Pharmacol 7 2/3 (1973) 198-205.", "Of even more importance, all of the above anti-inflammatory drugs produce gastrointestinal ulceration in experimental animals and in humans.", "Volume VII, p. 160, Side Effects of Drugs, (1971 Exerpta Media, Amsterdam);", "G. L. Bach, "Adverse Reactions of Antirheumatic Drugs", supra.", "Insofar as the state of the art is concerned, it is widely recognized that "it has not been possible to dissociate gastrointestinal toxicity from antiinflammatory activity.", """, "Side Effects of Drugs, supra at p. 100.", "It is therefore the principal objectives of my invention to provide anti-inflammatory drugs for use in treating arthritis in experimental animals which exhibit improved anti-inflammatory activities while at the same time providing drugs that are antiulcergenic and have acceptable levels of toxicity.", "SUMMARY OF THE INVENTION It has been quite unexpectedly determined that copper coordination compounds produced by reacting copper salts with the following classes of organic compounds produce products which when used in accordance with the following processes, exhibit excellent anti-inflammatory activity in animals, i.e., a warmblodded animal or mammalian subject, and which are anti-ulcer: 1.", "aromatic carboxylic acids or their alkaline earth salts;", "heterocyclic carboxylic acids or their alkaline earth salts;", "amino acids or their alkaline earth salts;", "amines;", "and 5.", "suitably substituted steroids.", "It has been empirically determined that the copper coordination compounds disclosed herein not only demonstrate excellent anti-inflammatory activity but that they are anti-ulcer and may be utilized both as anti-inflammatory agents in the treatment of arthritis and in the treatment of gastrointestinal ulcers in animals.", "In the treatment of inflammation and/or ulcers, the compounds are administered orally or parentrally.", "The copper coordination compounds, being relatively insoluble in water, are administered by dissolving them in saline solution to which a suitable suspending agent has been added.", "In treating inflammation by subcutaneously injecting test animals with the copper coordination compound so prepared it has been found that excellent anti-inflammatory results, in the test models hereinafter described, may be obtained if the dosages administered comprise about 2.5-165 mg.", "per kilogram of body weight.", "In treating gastrointestinal ulcers by orally introducing into test animals the copper coordination compounds of this invention it has been found that excellent results, in the test models hereinafter described, are obtained if the dosages administered comprise about 2 to 125 mg.", "per kilogram of body weight.", "DETAILED DESCRIPTION OF THE INVENTION For the purpose of more fully understanding the present invention, a copper coordination compound is intended to mean a compound whose molecular structure contains one or more copper atoms bonded to one or more atoms of one or more molecules or ions by coordinate covalant bonds.", "The copper coordination compounds of the present invention are prepared by reacting copper salts, preferably cupric cxhloric or cupric acetate with a member of the following classes of organic compounds: 1.", "aromatic carboxylic acids or their alkaline earth salts;", "heterocycline carboxylic acids or their alkaline earth salts;", "amino acids or their alkaline earth salts;", "amines;", "and 5.", "suitably substituted steroids.", "More specifically, it has been found that suitable compounds may be produced by reacting cupric chloride with the sodium salts of L &", "D tryptophan, anthranilic acid, 3,5-diisopropylsalicyclic acid, acetylsalicyclic acid, hydrocortisone-21-phosphate, dexamethasone-21-phosphate, salicyclic acid, 3-p-chlorophenyl-3,4,5,6,-tetrahydro-β-carboline-5-carboxylic acid, 3, 4, 5, 6-tetra-hydro-β-carboline-5-carboxylic acid, and 1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid;", "by reacting cupric chloride with 1-phenyl-5-aminotetrazole, ε aminocaproic acid, pyridine, a mixture of D and L-tryptophan, morpholine, and histamine;", "by reacting cupric chloride with the ammonium salt of hydrocortisone-21-hemisuccinic acid;", "by reacting cupric acetate with the sodium salts of 2[3(trifluoro-methyl)phenyl] aminonicotinic acid (sometimes referred to hereinafter as tpan), 1-carboxyisoquinoline, phenylcinchoninic acid, hydrocortisone-21-phosphate, and 4-n-butyl-1,2-diphenyl-3,5-pyrazolidinedione;", "by reacting cupric acetate with the ammonium salt of nicotinic acid;", "by reacting cupric acetate with D-pencillamine, 1-phenyl-5-aminotetrazole, D or L-aspartic acid, L-lysine, 2-carboxyindole;", "and by reacting cupric acetate with the potassium salt of 17-hydroxy-3-oxo-17α-pregn-4,6-diene-21 carboxylic acid.", "It is preferable to produce copper coordination solvates rather than anhydrous compounds as will be more fully appreciated by the following description.", "The compounds may be solvated with a lower alcohol (methanol or ethanol), acetone, pyridine, water or dimethyl sulfoxide.", "Following is a more detailed description of how the copper coordination compounds of the present invention may be prepared.", "Table V contains suggested structural formulae for some of my coordination compounds.", "Not all have been empirically determined.", "EXAMPLE 1: Bis-L-tryptophanato(O,N)copper(II),[Cu(II) (L-tryptophan) 2 ] L-tryptophan (5.0 g, 0.025 mol) was dissolved in 100 ml of H 2 O with a solution of NaOH (50%), filtered and back titrated if necessary with a solution of HCl (10%) until indicator paper showed the solution to be weakly basic.", "This solution was then dropped into 100 ml of H 2 O containing CuCl 2 dihydrate (3.3 g, 0.021 mol).", "After stirring for about one hour a precipitate formed and was collected by filtration.", "This blue precipitate was washed with H 2 O and diethylether, dried at 100° and 15 mm Hg overnight and weighted (4.7 g, 82% yield).", "A sample of this material on heating turned brown at 240° C. and finally decomposed at 260° C. Analysis Calcd.", "for C 22 H 22 N 4 O 4 Cu: C, 56.22;", "H, 4.72;", "N, 11.92.", "Found: C, 56.07;", "H, 4.89 and N, 12.16.", "EXAMPLE 2:BIS-D-tryptophanato(O,N)copper(II)[Cu(II)(D-tryptophan) 2 ].", "This coordination compound was prepared as described for the L isomer (example 1) using 5.0 g, 0.021 mol of D-tryptophan.", "After collecting the precipitate by filtration, washing with H 2 O, diethylether and acetone (250 ml), the precipitate was dried overnight at 100° and 15 mm Hg and weighed (4.3 g, 75% yield).", "A sample of this material decomposed slowly on heating to 269° C. Analysis Cacld.", "for C 22 H 22 N 4 O 4 Cu: C, 56.22;", "H, 4.72;", "N, 11.92.", "Found: C, 56.10, H, 4.72 and N, 12.00.", "EXAMPLE 3: Bisanthranilato(O,N)copper(II),[Cu(II)(anthranilate) 2 ] The sodium salt of anthranilic acid (5 g 0.04 mol) was prepared as decribed in example 1 in 150 ml of H 2 O with 50% NaOH.", "This solution was dropped into 300 ml of a stirred aqueous solution of CuCl 2 dihydrate (2.5 g, 0.016 mol).", "The precipitate which formed was removed by filtration and washed with H 2 O and diethylether (5×50 ml).", "After drying overnight @120° C. and 15 mm Hg the material weighed 6.1 g, 99% yield.", "A sample of this greenishblue material decomposed on heating to 240° C. and continued to decompose on heating to 290° C. Analysis Calcd.", "for C 14 H 6 N 2 O 4 Cu: C, 50.07;", "H, 3.60;", "N, 8.35.", "Found: C, 50.07;", "H, 3.77;", "N, 8.42.", "EXAMPLE 4: Bis(3,5-diisopropylsalicylato(O,O)copper(II)[Cu(II) (3,5-dips) 2 ] A solution of the sodium salt of 3,5-diisopropylsalicyclic diissopropylsalicyclic acid (5 g, 0.023 mol) was prepared as described in example 1 and added to 300 ml of a stirred aqueous solution of CuCl 2 dihydrate (1.59 g, 0.0336 mol).", "A brown precipitate formed which when recrystallized from ether gave green crystals.", "These crystals were filtered and dried at 125° C. and 15 mm Hg for three hours.", "The resulting brown crystalline material melted with decomposition over the range of 142°-144° C. Analysis Calcd.", "for C 26 H 34 O 3 Cu: C, 61.70;", "H, 6.77.", "Found: C, 61.49;", "H, 6.83.", "EXAMPLE 5: Tetra(μ-acetylsalicylato)biscopper(II),[Cu(II) 2 (aspirinate) 4 ] The sodium salt of acetylsalicylic acid was prepared by dissolving acetylsalicylic acid (30 g, 0.165 mol) in 200 ml of H 2 O at 0° C. with 50% NaOH so that the pH did not go above 11.0 and rarely reached 11.0.", "This was done over a period of 45 to 60 minutes.", "The final pH of the solution was about 8.7.", "The CuCl 2 solution prepared by adding 56.5 g, 0.330 mol of CuCl 2 dihydrate to 500 ml of water, was added to a stirred solution of sodium acetylsalicylate during a period of 10 to 15 minutes.", "Following the completion of this addition the blue precipitate was collected by filtration;", "washed with H 2 O (500 ml×2), acetone (400 ml×2) and diethylether (300 ml) and left to dry on a filter funnel attached to a water aspirator.", "After two days the powder was dried at 50° C. for 6- 7 hours and weighed (31.3 g, 90.6% yield).", "Analysis calculated for C 36 H 28 O 16 Cu 2 : C, 51.25;", "H, 3.35;", "Found: C, 51.20;", "H, 3.51.", "EXAMPLE 6: [2[3(trifluoromethyl)phenyl]aminonicotinato] 2n -(aqua) n -copper (II) n ,[Cu(II) n (tpan) 2n (H 2 O) n ] The sodium salt of 2[3 (trifluoromethyl)phenyl] aminonicotinic acid (20 g, 0.0708 mol) was prepared as described in example 1.", "The solution of this salt was then added to about 300 ml of a saturated, stirred solution of cupric acetate monohydrate.", "The resultant greenish precipitate was collected by filtration and dissolved in 200 ml of diethylether.", "The ether solution was then dropped into about 4 liters of boiling skellysolve A. The resultant precipitate was collected from the hot solution by filtration, dried at 125° C. for three hours at 15 mm Hg and weighed (16 g, 70% yield).", "A sample of this material melted with decomposition over the range of 201° to 208° C. Analysis Calcd.", "for C 52 H 36 O 10 N 8 F 12 Cu: C, 48.49;", "H, 2.82;", "N, 8.70.", "Found: C, 48.53;", "H, 2.66;", "N, 8.91.", "EXAMPLE 7: D-penicillaminato-(aqua) 1 [.", "].5 -copper(I),[Cu(I) n (D-pen) n (H 2 O) 1 [.", "].5n ] D-penicillamine (5 g, 0.0335 mol) was dissolved in 50 ml of water.", "The solid cupric acetate monohydrate (6.68 g, 0.017 mol) was then added to the solution at such a rate so as to not exceed its rate of solution.", "Upon the completion of this addition the solution was dark gray.", "About 50-100 ml of H 2 O was then added and the mixture left to stir for about 30 minutes.", "The resultant gray precipitate was collected by filtration leaving a blue filtrate (125 ml).", "This blue filtrate was subsequently diluted with about 375 ml of acetone and set aside for use in example 8.", "The air-dried gray powder weighed 4.3 g, 54.0% yield.", "A sample of this material decomposed over the range of 155°-157° C. Analysis Calcd.", "for C 5 H 9 SNO 3 [.", "].5 Cu: C, 25.26;", "H, 5.10;", "N, 5.89.", "Found: C, 25.32;", "H, 5.03;", "N, 5.47.", "EXAMPLE 8: (D-penicillaminato) 2n -(aqua) 2n -copper(II),[Cu(II) n (D-pen) 2n (H 2 O) 2n ] On standing, the acetone diluted blue filtrate described in the preparation of Example 7 gave a gray precipitate which was collected by filtration and this filtrate also set aside.", "The gray solid was washed with 60 ml of water and the remaining light tan solid washed with 60 ml of acetone air dried and weighed (1.15 g, 17.4% yield).", "A sample of this solid melted with decomposition over the range of 155° to 157° C. Analysis Calcd.", "for C 10 H 24 O 6 N 2 Cu: C, 30.33;", "H, 6.11;", "N, 7.08.", "Found: C, 30.42;", "H, 6.49;", "N, 6.72.", "EXAMPLE 9: (D-pencillamine disulfide) n -(aqua) 3n copper(II) n ,[Cu(II) n (D-pen disulfide) n (H 2 O) 3n ] The acetone-water filtrate obtained after removing example 8 from the blue acetone filtrate, described above, was concentrated to about 100 ml and diluted with 400 ml of acetone.", "A blue precipitate (1.3 g, 9.4% yield) was obtained following filtration, washing with acetone and air drying.", "A sample of this material decomposed over the range of 157° to 158° C. After drying twice at 73° and 15 mm Hg overnight a sample of this material decomposed over the range of 173° to 175° C. Analysis Calcd.", "for C 10 H 24 N 2 S 2 O 7 Cu: C, 29.15;", "H, 5.87;", "N, 6.80.", "Found: C, 29.43;", "H, 5.76;", "N, 6.36.", "EXAMPLE 10: (Acetato) 2n -(1-phenyl-5-aminotetrazolato) n -copper(II) n ,[Cu(II) n (pat) n (acetate) 2n ] Five grams of cupric acetate monohydrate (0.012 mol) was dissolved in 20 ml of H 2 O. This solution was diluted with 100 ml of methanol.", "5 g (0.31 mol) of 1-phenyl-5-aminotetrazole was added to obtain a blue gel.", "This gel was filtered and the resulting blue flakes were washed with about 400 ml of methanol until the washings were no longer blue.", "The filtrate was then concentrated to about 150 ml and stored for about one week in the refrigerator.", "A precipitate formed and was removed by filtration.", "This green crystalline solid was air dried and weighed (3.8 g, 17.9% yield).", "A sample of this solid decomposed over the range of 186°-189° C. Analysis Calcd.", "for C 22 H 26 N 10 O 8 Cu 2 : C, 38.54;", "H, 3.82;", "N, 20.43.", "Found: C, 38.42;", "H, 3.94;", "N, 20.92.", "EXAMPLE 11: (1-phenyl-5-aminotetrazolato) 2n -(chloride) 2n -copper(II) n ,[Cu(II) n (pat) 2n (HCl) 2n ] Five grams (0.012 mol) of 1-phenyl-5-aminotetrazole was dissolved in 30 ml of methanol, then 5 g (0.029 mol) of CuCl 2 dihydrate dissolved in 25 ml of methanol was added to the stirred solution of tetrazole.", "The resulting solution was filtered and set aside.", "Three subsequent crops of a green solid were obtained following filtration and concentration of the filtrate.", "The combination of these were air dried and weighed (5 g, 17.7% yield).", "A sample of this material decomposed on heating over the range of 184° to 185° C. Analysis Calcd.", "for C 14 H 14 N 10 CuCl 2 : C, 36.81;", "H, 3.09;", "N, 30.67.", "Found: C, 36.65;", "H, 3.17;", "N, 31.03.", "EXAMPLE 12: (D-Aspartato) n (aqua) 3 [.", "].5n -copper(II)) n ,[Cu(II) n (D-aspartate) n (H 2 O) 3 [.", "].5n ] This material is made in a manner similar to the preparation of example 1 using D-aspartic acid in place of L-tryptophan.", "Analysis calculated for C 4 H 12 N O 7 [.", "].5 Cu: C, 18.69;", "H, 4.66.", "Found: C, 18.55;", "H, 4.92.", "EXAMPLE 13: (L-Aspartato) n -(aqua) 3 [.", "].5n -copper(II) n ,[Cu(II) n (L-aspartate) n (H 2 O) 3 [.", "].5n ] This material is made in a manner similar to the preparation of example 1 using L-aspartic acid in place of L-tryptophan.", "Analysis calculated for C 4 H 12 N O 7 [.", "].5 Cu: C, 18.69;", "H, 4.66.", "Found: C, 18.41;", "H, 4.73.", "EXAMPLE 14: (L-Lysino) n -(chloro) 2n -(aqua) n -copper(II) n ,[Cu(II) n ,(L-lysinate) n (Cl) 2n (H 2 O) n ] This material is made in a manner similar to example 1 using L-lysine in place of L-tryptophan.", "A sample of this material decomposed on heating over the range of 169° to 170° C. Analysis calculated for C 6 H 16 N 2 O 3 CuCl 2 : C, 24.10;", "H, 5.40;", "Cl, 23.70;", "N, 9.38.", "Found: C, 24.54;", "H, 5.07;", "Cl, 24.00;", "N, 9.36.", "EXAMPLE 15: (L-Lysino) 2n -(chloro) 2n -(aqua) n -cooper(II) n ,[Cu(II) n (L-lysinate) 2n (Cl) 2n (H 2 O) n ] This material is made in a manner similar to example 1 using L-lysine in place of L-tryptophan.", "A sample of this compound decomposed on heating up to and over the range 210° to 214° C. Analysis calculated for C 12 H 32 N 4 O 5 CuCl 2 : C, 32.40;", "H, 6.80;", "Cl, 12.60.", "Found: C, 32.56;", "H, 7.04;", "Cl, 12.24.", "EXAMPLE 16: Bis(D,L-tryptophanato(O,N)copper(II),[Cu(II)(D,L-tryptophan) 2 ] This coordination compound was prepared and isolated as described in example 1 using a mixture of D and L-tryptophan in place of L-tryptophan.", "Analysis Calcd.", "for C 22 H 22 N 4 O 4 Cu: C, 56.22;", "H, 4.72.", "Found: C, 55.58;", "H, 4.87.", "EXAMPLE 17: (ε-aminocaproato) n -(chloro) 1 [.", "].5n -(methanol) 0 [.", "].5n -copper(II) n ,[Cu(II) n (ε-aminocaproate) n (Cl 1 [.", "].5n (CH 3 OH) 0 [.", "].5n ] This coordination compound was prepared by stirring a suspension of 10 g (0.08 mol) of ε-aminocaproic acid in 200 ml of methanol and slowly adding 10 g (0.065 mol) of solid cupric chloride dihydrate.", "The resultant green precipitate was collected by filtration washed with methanol, dried at 25° C. and 15 mm Hg overnight, and weighed (10.5 g, 51% yield).", "A sample of this material decomposed over the range of 157° to 158° C. Analysis Calcd.", "for C 7 H 15 [.", "].5 O 2 [.", "].5 CuCl 1 [.", "].5 : C, 29.53;", "H, 5.91;", "Cl, 20.11.", "Found: C, 29.97;", "H, 6.06;", "Cl, 20.36.", "EXAMPLE 18: (ε-aminocaproato) n -(chloro( 2n -(aqua) 0 [.", "].5n -copper(II) n ,[Cu(II) n (ε-aminocaproate) n (Cl) 2n (H 2 O) 0 [.", "].5n ] This coordination compound was obtained from the filtrate described in example 17.", "Following concentration of the filtrate and methanol washings to about 100 ml of bluish-green precipitate formed.", "This precipitate was collected by filtration dried at 25° C. at 15 mm Hg and weighed (4.6 g, 21% yield).", "A sample of this material decomposed on heating over the range of 193° to 194° C. Analysis Calcd.", "for C 6 H 14 NO 2 [.", "].5 Cl 2 Cu: C, 26.24;", "H, 5.14;", "Cl, 25.82.", "Found: C, 26.29;", "H, 5.28;", "Cl, 25.39.", "EXAMPLE 19: tetra(μ-acetato)bis(monopyridino)copper(II),[Cu(II) n (pyridine) n (acetate) 2n ] This coordination compound was prepared by adding 10 g (0.025 mol) of cupric acetate monohydrate to 70 ml of pyridine and the mixture heated while stirring at 100° C. The hot suspension was filtered and the resulting precipitate collected by filtration and washed with 200 to 300 ml of diethylether.", "A sample of this green solid decomposed on heating over the range of 214° to 216° C. When the ether-pyridine filtrate cooled a second precipitate, which was bluish, was obtained.", "Removal by filtration and washing with ether gave a second crop of the green material in the filtrate.", "This green solid had a decomposition range of 216° to 218° C. The mixture decomposition range of 216° to 218° C. was observed for a sample of the combination of the two green solids.", "Total yield was 12 g, 92%.", "Analysis Calcd.", "for C 18 H 22 N 2 O 8 Cu 2 : C, 41.46;", "H, 4.25;", "N, 5.37.", "Found: C, 41.87;", "H, 4.54;", "N, 5.23.", "EXAMPLE 20: Bispyridinobischlorocopper(II),[Cu(II)(pyridine) 2 (Cl) 2 ] This composition was prepared by dissolving 9.42 g (0.062 mol) of CuCl 2 dihydrate in 95% ethanol and adding 15 g (0.19 mol) of pyridine slowly to the stirred solution.", "The resultant blue precipitate was removed by filtration, washed with 95% ethanol (200 ml), dried at about 50° C. for 24 hours and weighed (19.8 g, 35.6% yield).", "A sample of this material decomposed over the range of 225° to 275° C. Analysis Calcd.", "for C 10 H 10 N 2 CuCl 2 : C, 41.32;", "H, 3.44.", "Found: C, 41.25;", "H, 3.52.", "EXAMPLE 21: Bismorpholoniumtetrachlorocopper(II),[Cu(II)(morpholine) 2 (Cl) 2 (HCL) 2 ] This coordination compound was prepared according to the published procedure of W. H. C. Rueggeberg, G. N. Jarman and R. B. Wearn, J.A.C.S.", ", 69, 1222 (1947) incorporated by reference herein.", "Starting with 14.5 g (0.167 mol) of morpholine the coordination compound was obtained in 41% yield.", "A sample of this green crystalline melted with decomposition over the range of 167°-170° C. Analysis Calcd.", "for C 8 H 20 N 2 O 2 CuCl 4 : C, 25.17;", "H, 5.28;", "N, 7.34.", "Found: C, 25.17;", "H, 5.41;", "N, 7.21.", "EXAMPLE 22: (Histamino) n -(chloro) 2n -(hydrochloro) 2n -copper(II) n ,[Cu(II) n (histamine) n (Cl) 2n (HCl) 2n ] This coordination compound was prepared by mixing 5 g (0.048 mol) of cupric chloride dihydrate in 200 ml of methanol and concentrating to 135 ml.", "On standing a tan solid precipitated.", "This was removed by filtration and the filtrate concentrated to 80 ml.", "Upon addition of 40 ml of diethylether to this concentrate a light green solid precipitated.", "After removal by filtration and air drying this material was weighed (4.0 g, 23% yield).", "A sample decomposed over the range of 185° to 189° C. with softening at 182° C. Analysis Calcd.", "for C 5 H 10 N 3 Cl 4 Cu: C, 18.91;", "H, 3.17;", "N, 13.24.", "Found: C, 18.90, H, 3.30;", "N, 13.30.", "EXAMPLE 23: (Sodium) 4 -(salicylato) 4 -copper(II) 2 ,[Cu(II) 2 (salicylate) 4 (Na) 4 ] This material was prepared from the material obtained in example 24 with the addition of sodium ethoxide in suitable solvent.", "Analysis calculated for C 28 H 16 O 12 Cu 2 Na 4 were found to be within ±0.4% of the theoretical values.", "EXAMPLE 24: (Salicylato) 2n -(aqua) 4n -copper(II) n ,[Cu(II)(Salicylate) 2 (H 2 O) 4 ] This material may be prepared as described in example 1 using salicylic acid in place of L-tryptophan.", "Analysis calculated for C 14 H 18 O 10 Cu: C, 41.03;", "H, 4.43.", "Found: C, 41.24;", "H, 4.52.", "EXAMPLE 25: (Pyridine-3-carboxylato( 2n -(aqua) 1 [.", "].5n -copper(II),[Cu(II) 2n (nicotinate) 4n (H 2 O) 3n ] This coordination compound was prepared by dissolving 10 g (0.08 mol) nicotinic acid in 100 ml of water with concentrated NH 4 OH so that the final pH was 7.0.", "A cupric chloride solution, prepared by dissolving 21.6 g (0.14 mol) of cupric chloride dihydrate in 200 ml of water, was stirred while the ammonium salt of nicotinic acid was added dropwise.", "The blue precipitate was collected by filtration, washed with 500 ml of water and air dried.", "The resulting material was dried at 80° C. and weighed (10.7 g, 80% yield).", "A sample of this material decomposed on heating up to and through the range of 265° to 266° C. Analysis Calcd.", "for C 24 H 22 O 11 N 4 Cu 2 : C, 43.05;", "H, 3.31;", "N, 8.37.", "Found: C, 43.25;", "H, 3.00;", "N, 8.12.", "EXAMPLE 26: (Isoquinoline-1-carboxylato) 2n -copper(II) n ,[Cu(II) n (1-carboxyisoquinoline) 2n ] The copper coordination compound of 1-carboxyisoquinoline (5 g 0.029 mol) was prepared by adding to its solution of the sodium salt, prepared as in example 1 in 200 ml of water using 1-carboxyisoquinoline in place of L-tryptophan, 60 ml of a saturated aqueous solution of cupric acetate monohydrate.", "The resultant purple precipitate was collected by filtration, washed with 500 ml of water and dried overnight at 100° C. and 15 mm Hg.", "A sample of this material (4.0 g, 70.2% yield) decomposed over the range of 295° to 296° C. Analysis Calcd.", "for C 20 H 12 N 2 O 4 Cu: C, 58.84;", "H, 2.97;", "N, 6.87.", "Found: C, 58.49;", "H, 3.14;", "N, 6.79.", "EXAMPLE 27: (2-Phenyl-4-isoquinoline-carboxylato) 2n -(aqua) 2n -copper(II) n ,[Cu(II) n (2-phenyl-4-carboxyisoquinoline) 2n (H 2 O) 2n ] This coordination compound was synthesized from the sodium salt of phenylcinchoninic acid (25 g, 0.15 mol), which was prepared as described in example 1 using "2-phenyl-4-isoquinoline-carboxylic acid"", "in place of L-tryptophan in 550 ml of water.", "The solution of the sodium salt was dropped into a stirred solution of cupric chloride dihydrate (14.2 g, 0.09 mol).", "The resulting green precipitate was collected by filtration, washed with methanol, water and then air dried and weighed (29.5 g, 67% yield).", "A sample of this material decomposed on heating over the range of 228° to 229° C. Analysis Calcd.", "for C 64 H 48 N 4 O 12 Cu 2 : C, 64.48;", "H, 4.06;", "N, 4.70.", "Found: C, 64.55;", "H, 3.80;", "N, 4.61.", "EXAMPLE 28: (Indole-2-carboxylato) 3n -(acetato) n -aqua) 0 [.", "].5n,[Cu(II) n (2-carboxyindole) 3n (acetate) n (H 2 O) 0 [.", "].5n ] This copper coordination compound was prepared from the parent acid 2-carboxyindole (4.5 g, 0.028 mol) as in example 1, using cupric acetate.", "The green precipitate was collected by filtration, air dried for several days, suspended in boiling methanol and again collected by filtration.", "It was then dried at 100° C. and 15 mm Hg overnight and at 125° and 15 mm Hg for 3 hours.", "A sample of this material (3.0 g, 23.3% yield) decomposed over the range of 249°-255° C. Analysis Calcd.", "for C 29 H 22 N 3 O 9 Cu: C, 56.91;", "H, 3.59;", "N, 6.86.", "Found: C, 56.87;", "H, 4.03;", "N, 6.62.", "EXAMPLE 29: (Indole-2-carboxylato) 3n -(acetato) n -(aqua) 3 [.", "].5n,[Cu(II) n (2-carboxyindole) 3n (acetate) n (H 2 O) 0 [.", "].5n ] This material was prepared as described in example 1 using 2-carboxyindole in place of L-tryptophan and dried at 100° C. and 15 mm Hg over the weekend.", "A sample of this material did not melt but did turn brown, as did the material in example 28, on heating to 260°.", "Analysis Calcd.", "for C 29 H 28 N 3 O 12 Cu: C, 52.29;", "H, 4.20;", "N, 6.30.", "Found: C, 51.85;", "H, 3.78;", "N, 6.59.", "EXAMPLE 30: (3-p-chlorophenyl-3,4,5,6-tetrahydro-β-carboline-5-carboxylato) 2 n -(aqua) 2n -copper(II) n ,[Cu(II) n (cp-tcca) 2n (H 2 O) 2n ] The copper coordination compound of the parent acid (5 g, 0.015 mol) was prepared as described for example 1 except 3-p-chlorophenyl-3,4,5,6-tetrahydro-β-carboline-5-carboxylic acid was substituted for L-tryptophan.", "An olive drab precipitate was collected by filtration, washed with 500 ml of H 2 O, 300 ml of diethylether and then with acetone until the washings were colorless.", "This material was dried at 100° C. overnight and 110° C. at 15 mm Hg for 3 hours before dissolving in acetone and precipitated with Skellysolve B. This material (2 g, 40% yield) was then dried overnight at 60° C. and 15 mm Hg and again at 125° C. and 15 mm Hg.", "A sample of this material decomposed over the range of 205° to 210° C. Analysis Calcd.", "for C 36 H 32 Cl 2 N 4 O 6 Cu: C, 57.56;", "H, 4.30;", "N, 7.46.", "Found: C, 57.16;", "H, 4.15;", "N, 6.96.", "EXAMPLE 31: (3,4,5,6-Tetrahydro-β -carboline-5-carboxylato) 2n (aqua) 2 [.", "].5n -copper(II) n ,[Cu(II) n (tcca) 2n (H 2 O) 2 [.", "].5n ] The copper coordination compound of the parent acid (5 g, 0.023 mol) was prepared as described for example 1 except that 3,4,5,6-tetrahydro-β-carboline-5-carboxylic acid was substituted for L-tryptophan.", "This dark green solid was washed with 500 ml of water, then suspended in 500 ml of boiling acetone and collected by filtration.", "Drying was done at 100° C. at atmospheric pressure for 24 hours and then at 110° C. and 15 mm Hg for 3 hours.", "Subsequent leaching with hot propylene glycol gave an insoluble material (3.3 g, 52.8% yield) which rapidly decomposed on heating to 294° C. Analysis Calcd.", "for C 24 H 27 N 4 O 6 [.", "].5 Cu: C, 53.47;", "H, 5.05 and N, 10.40.", "Found: C, 53.54;", "H, 4.69 and N, 10.58.", "EXAMPLE 32: (Hydrocortisone-21-phosphato) 2n -(aqua) 9n -copper(II) 3n ,[Cu(II) 3n (HC-21-phosphate) 2n (H 2 O) 9n ] This coordination compound was prepared by dissolving 1 g (0.002 mol) of the disodium salt of hydrocortisone-21-phosphate in 25 ml of water and adding this solution dropwise to a stirred solution of cupric acetate monohydrate, prepared by adding 0.79 g (0.004 mol) of cupric acetate monohydrate to 25 ml of water.", "After the addition was complete, stirring was continued for one-half hour before the light blue precipitate was collected by filtration and washed with 500 ml of water before air drying.", "The yield was 0.185 g, 34%.", "On heating a sample of this material to 209° C. it decomposed.", "Analysis Calcd.", "for C 42 H 78 O 25 P 2 Cu 3 : C, 40.82;", "H, 6.36.", "Found: C, 40.59;", "H, 6.18.", "EXAMPLE 33: (Hydrocortisone-21-phosphato) 2n -(aqua) 7n -copper(II) 3n ,[Cu(II) 3n (HC-21-phosphate) 2n (H 2 O) 7n ] This coordination compound was prepared by dissolving 1 g (0.002 mol) of the disodium salt of hydrocortisone-21-phosphate in 100 ml of water, adding 1 drop of concentrated hydrochloric acid to give a pH of 6.6 and adding this solution dropwise to a stirred solution of cupric chloride dihydrate (1 g, 0.006 mol) in 50 ml of water.", "After the addition was complete the mixture was allowed to stir for one hour and the light blue precipitate collected by filtration, washed with 200 ml of water, air dried and weighed (400 mg, 33% yield).", "A sample of this material gradually decomposed on heating to 210° C. Analysis Calcd.", "for C 42 H 74 O 23 P 2 Cu 3 : C, 42.05;", "H, 6.22.", "Found: C, 42.00;", "H, 6.21.", "EXAMPLE 34: (Hydrocortisone-21-hemisuccinato) 4n -(aqua) 6n -copper(II) 2n ,[Cu(II) 2n (HC-21-hemisuccinate) 4n (H 2 O) 6n ] This coordination compound was prepared by dissolving 1 g (0.002 mol) of hydrocortisone-21-hemisuccinic acid in 250 ml of water with concentrated ammonium hydroxide.", "The resulting pH was 9.0 and was adjusted to pH 7.0 with a 10% solution of hydrochloric acid.", "This solution was then added dropwise to a stirred solution of cupric chloride dihydrate (1 g, 0.006 mol) dissolved in 250 ml of water.", "The resulting light blue-green precipitate was collected, air dried and weighed (1 g, 96% yield).", "A sample of this material decomposed on heating over the range of 191° to 195° C. Analysis Calcd.", "for C 100 H 144 O 38 Cu 2 : C, 57.71;", "H, 6.97.", "Found: C, 57.41;", "H, 7.26.", "EXAMPLE 35: (Hydrocortisone-21-hemisuccinato) 4n -(aqua) 7n -copper(II) 2 [.", "].5n [Cu(II) 2 [.", "].5n (HC-21-hemisuccinate) 2n (H 2 O) 7n ] This coordination compound was prepared by dissolving 1 g (0.002 mol) of hydrocortisone-21-hemisuccinic acid in 20 ml of water with concentrated ammonium hydroxide.", "The resulting pH was 9.5.", "This solution was then added dropwise to a stirred solution of cupric chloride dihydrate (1 g, 0.006 mol) dissolved in 15 ml of water.", "The light blue precipitate which formed was collected by filtration, air dried and weighed (1.2 g, 99% yield).", "A sample of this material decomposed on heating over the range of 196° to 197° C. Analysis Calcd.", "for C 100 H 160 O 46 Cu 5 : C, 49.71;", "H, 6.68.", "Found: C, 49.91;", "H, 6.63.", "EXAMPLE 36: (9α-Fluoro-11β, 17α, 21-trihydroxy-16α-methyl-1,4-pregnadiene-3,20-dione-21-phosphato).", "sub[.", "].2n -(aqua) 7n -copper(II) 3n ,[Cu(II) 3n (dexamethasone-21-phosphate) 2n (H 2 O) 7n ] This coordination compound was prepared by dropping a solution of the disodium salt of dexamethasone-21-phosphate (9 g, 0.017 mol) dissolved in 100 ml of water, into a stirred solution of 100 ml of water containing 4.6 g (0.003 mol) of cupric chloride dihydrate.", "After the addition was completed an additional 300 ml of water was added.", "The resulting light blue precipitate was collected by filtration, washed with water, air dried and weighed (8.1 g, 75% yield).", "A sample of this material gradually decomposed on heating to 300° C. Analysis Calcd.", "for C 88 H 140 O 46 P 4 F 4 Cu 6 : C, 42.02;", "H, 5.61.", "Found: C, 42.04;", "H, 5.5.", "EXAMPLE 37: (9α-Fluoro-11β, 17α-21-trihydroxy-16α-methyl-1,4-pregnadiene-3,20-dione-21-phosphato) 2n -(aqua) 1 [.", "].5n -copper(II) 3n ,[Cu(II) 3n (dexamethasone-21-phosphate) 2n (H 2 O) 1 [.", "].5n ] This coordination compound was prepared by taking 2 g (0.0008 mol) of the material prepared in example 36 and suspending it in a stirred methanol for two hours to remove some of the water of hydration.", "After air drying this material was dried at 45° C. and 15 mm Hg overnight.", "A sample of this material also decomposed on heating to 300° C. Analysis Calcd.", "for C 88 H 118 O 35 P 4 F 4 Cu 6 : C, 45.62;", "H, 5.13.", "Found: C, 45.51;", "H, 5.48.", "EXAMPLE 38: [1-(p-Chlorobenzoyl)-5-methoxy-2-methylindole-3- acetato] 4n -(aqua) 4n -copper(II) 2n ,Cu(II) 2n [1-p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetate] 4n (H 2 O) 4n ] This coordination compound was synthesized from the sodium salt of the parent acid (5 g, 0.014 mol), prepared as in example 1 except 1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid was used in place of L-tryptophan, in 200 ml of water.", "The solution of the sodium salt was dropped into a stirred 300 ml water solution of cupric chloride dihydrate (1.95 g, 0.013 mol).", "The resultant green precipitate was collected by filtration, washed with water, air dried and weighed (5.6 g, 98% yield).", "A sample of this material decomposed on heating to 190° C. Analysis Calcd.", "for C 76 H 68 O 20 N 4 Cl 4 Cu 2 : C, 56.13;", "H, 4.21;", "N, 3.44.", "Found: C, 56.00;", "H, 3.78;", "N, 3.40.", "EXAMPLE 39: [1-(p-Chlorobenzoyl)-5-methoxy-2-methylindole-3-acetato] 4n -(acetone) 2n -copper(II) 2n , Cu(II) 2n (1-p-chlorobenzoyl)-5-methoxy-3-methylindole-3-acetate] 4n (CH 3 COCH 3 ) 2n ] This coordination was prepared in a manner similar to that described for example 38, using twice the amount of parent acid and cupric chloride dihydrate.", "However, after the green precipitate was collected by filtration it was leached with 1 liter of acetone and the leachate concentrated to 500 ml.", "On standing, additional green crystals formed in the acetone solution.", "These were collected by filtration, air dried and weighed (6.9 g, 62% yield).", "A sample of this material decomposed on heating up to and over the range of 190° to 193° C. Analysis Calcd.", "for C 82 H 72 O 18 N 4 Cl 4 Cu 2 : C, 58.81;", "H, 4.79;", "N, 3.21.", "Found: C, 58.96;", "H, 4.34;", "N, 3.35.", "EXAMPLE 40: (4-n-Butyl-1,2-diphenyl-3,5-pyrazolidinedione) 2n -copper(II) n ,[Cu(II) n (4-n-butyl-1,2-diphenyl-3,5-pyrazolidinedione) 2n ] A solution of the sodium salt of the parent compound 4-n-butyl-1,2-diphenyl-3,5-pyrazolidinedione, (5 g, 0.015 mol) dissolved in 50 ml of 95% ethanol was diluted with 150 ml of H 2 O. To this stirred solution was added 2.73 g (0.007 mol) of cupric acetate monohydrate, in small aliquats.", "The greenish precipitate which formed was collected by filtration, dried at 95° C. and 15 mm Hg overnight and weighed (4.5 g, 94.5% yield).", "A sample of this material softened and melted over the range of 65° to 75° C. Analysis Caldcd.", "for C 38 H 38 N 4 O 4 Cu: C, 67.29;", "H, 5.65;", "N, 8.26.", "Found: C, 67.61;", "H, 5.43;", "N, 8.28.", "EXAMPLE 41: (17-Hydroxy-3-oxo-17α-pregn-4,6-diene-21-carboxalato) 2n -(aqua) 2n -copper(II) n ,[Cu(II) n (17-hydroxy-3-oxo-17α-pregn-4,6-diene-21-carboxylato) 2n (H 2 O) 2n ] The potassium salt of the parent acid (17-hydroxy-3-oxo-17α-pregn-4,6-diene-21-carboxylic acid) (5 g, 0.013 mol) was dissolved in 50 ml of water.", "This solution was dropped into a stirred solution of cupric acetate monohydrate, prepared by dissolving 5 g (0.012 mol) in 50 ml of water.", "After the addition was completed the mixture was left to stir for an additional one-half hour before removing the precipitate by filtration.", "This precipitate was washed with 500 ml of water before air drying followed by drying at 30° and 15 mm Hg over the weekend.", "A 5 g, 24% yield was obtained.", "A sample of this material decomposed on heating over the range of 168°-169° C. This material was redried at 40° and 15 mm Hg before obtaining elemental analysis.", "Analysis Calcd.", "for C 88 H 128 O 22 Cu 2 : C, 64.88;", "H, 7.67.", "Found: C, 64.44;", "H, 7.87.", "Inflammation Test Models Employed In order to test the anti-inflammatory activities of my copper coordination compounds, the following test models were employed: (1) Carrageenin Foot Edema Model as described in Experentia, 6, pp. 469-71, "Zur Frage des Mechanis Mos der Hemmung des Bindegebswachstums durch Cortisone"", "(1950);", "(2) Cotton Wad Granuloma Model as described in J. Pharmacol.", "Expt'l.", "Ther.", ", 141, pp. 369-76, "Anti-inflammatory and Antipyretic Activities of Indomethacin, 9-(p-chlorobenzoyl)-5-Methoxy-2-Methyl-Indole-3-Acetic Acid"", "(1963);", "and (3) Polyarthritis Model as described in Nature, 224, pp. 1320-21, "Effect of Prostaglandin E 2 on Adjuvant Arthritis"", "(1969).", "The foregoing literature references were followed in the following tests unless otherwise stated and they are incorporated by reference herein.", "Each test model will only be briefly described.", "Each test model is a recognized and accepted model for testing drugs for the treatment of arthritis.", "Carrageenin Foot Edema Model In this test model test rats were injected with carageenin in a hind paw one hour after administration of the copper coordination compound.", "The carrageenin induced inflammation.", "The rats were male, of the Sprague Dawley variety and weighed on the average 120 grams.", "The copper coordination compounds were first introduced subcutaneously.", "The dosages were compounded as follows: TABLE A______________________________________Copper CoordinationCompoundWeight in Milligrams Saline Solution Suspending Agent______________________________________0.5 0.2 ml several drops1 0.2 ml per 10 ml2 0.2 ml5 0.2 ml25 0.2 ml______________________________________ The suspending agent was Tween 80, a nonionic surfactant sold by the Atlas Powder Company.", "A full description of it is contained at p. 648 of Remingtons Practice of Pharmacy (11th ed.", ", Martin &", "Cook, The Mack Publishing Co., Easton Pa.", "1956).", "Generally they may be described as a complex mixture of polyoxyethylene ethers of mixed oleic esters of sorbitol anhydrides.", "The initial screening dosage was 25 mg of the copper coordination compound given in one injection to ten rats.", "Compounds which were active received further testing at 5.0 mg and lower dosages.", "Each dosage was administered to at least ten rats.", "A dose was rated active if it caused a significant decrease (P<0.05) in the circumference of the feet injected with carrageenin six hours after administration.", "Compounds were rated active if they possessed a subcutaneous potency of ≧1%.", "As a reference standard, saline solution plus suspending agent was subcutaneously administered to each of the ten rats.", "Cotton Wad Granuloma This test utilizes the discovery that when cotton is introduced subcutaneously into a rat's skin it becomes encapsulated with connective tissue forming a granuloma.", "This is a manifestation of a local inflammatory response.", "The rats utilized were male, of the Sprague Dawley variety and weighed on the average 175-200 gm.", "The rats were given an adrenalectomy one day prior to implantation.", "The cotton pellets, sterilized, each weighing 32-50 mg but for each experiment not varying ±1 mg.", "were inserted in each animal adjacent to the abdomen.", "The copper coordination compounds were subcutaneously introduced in various dosages daily for two days.", "The dosages were prepared in accordance with Table A and the description given in explanation thereof.", "Each dose was administered to at least ten rats.", "The initial screening dose was 20 mg.", "The compounds were rated active if they caused a significant decrease (P<0.05) in the adjusted weight of the granuloma tissue encapsulating the implanted cotton.", "In order to arrive at the adjusted weight a reference standard, hydrocortisone, 0.5 mg.", "was administered subcutaneously to ten reference standard rats.", "After two days, the rats, in the test model and reference standard were sacrificed and the granulomas from each were removed, weighed, dried and reweighed.", "The adjusted weights were calculated as wet granuloma from test model compared to wet granuloma from reference standard and dry granuloma from test model compared to dry granuloma from reference standard.", "Polyarthritis Model In this model the test rats, male Sprague Dawley rats, 160-180 g, were inoculated intradermally at the base of the tail with a Freund type adjuvant as described in Nature, supra, to wit: 0.6 mg dry, heat-killed Mycobacterium butyricum (purchased from Difco) suspended in 0.05 ml of paraffin oil.", "The test rats were injected subcutaneously daily for 16 days with varying dosages of copper coordination compound prepared by mixing the copper compound with saline solution and suspending agent in the proportion set forth in Table A and in the manner described in connection therewith.", "The initial screening dose was 5 mg.", "Each dose was administered to at least twelve rats.", "As a control group, twelve rats were also injected subcutaneously with saline solution plus suspending agent.", "On day 16 (day 1=day of inoculation) the rats were sacrificed.", "The circumference of the tibiotarsal (ankle) joint was used as a measure of the severity of the inflammation.", "Table I and Table IV set forth the results of the foregoing tests and Table I includes in addition comparisons of the anti-inflammatory activities of my compound vs.", "hydrocortisone.", "Ulcer Test Models Employed To determine the ulcergenicity of my copper coordination compounds, two different test models were employed--the Shay rat test and the Corticoid Induced Rat Ulcer Test.", "These are commonly employed tests described in the literature.", "Shay, et al, "A Simple Method for the Uniform Production of Gastric Ulceration in the Rat,"", "Gastroenterology 5, 43-61(1945);", "and Robert, A. et al.", ", Proc.", "Soc.", "Expt'l.", "Biol.", "99, pp. 443-47, "Ulcergenic Properties of Steroids"", "(1958), incorporated by reference herein.", "Shay Rat Test The procedure set forth in the above described method by Shay et al was followed.", "The rats were males of the Sprague Dawley variety, weighing 200-250 grams, which had been fasted for 72 hours.", "The control group of twelve rats received a saline and Tween 80 solution introduced intragastrically.", "An initial screening dose of 50 mg copper coordination compound, mixed with saline solution and Tween 80 suspending agent was introduced intragastrically into twelve rats.", "If the compounds displayed activity, as determined in the manner described below, dosages of either 0.5 mg, 1 mg, 2.5 mg, or 10 mg were administered.", "Each dose was given to at least twelve rats.", "The following Table B shows how the dosages were formulated.", "TABLE B______________________________________ Saline SolutionCopper Compound (mg) ML Suspending Agent______________________________________0.5 1 1 drop1 1 1 drop2.5 1 1 drop10 1 1 drop50 1 1 drop______________________________________ The activity of the dosages was arrived at by sacrificing the rats after 19 hours and determining the size and number of ulcers present.", "The incidence of ulcers in rats receiving the dosages of copper compounds were compared with the incidence of ulcers in rats in the control group.", "The compounds were rated active if the comparison showed that the compound significantly inhibited ulceration (P<0.05).", "Corticoid-Induced Rat Ulcer Test 8 mg of Δ 1 -cortisol in about 0.2 ml corn oil was injected subcutaneously into each rat in two groups of male Sprague Dawley rats (about 150 to 165 g) daily for four days.", "The rats in the control group received no other compound, while the rats in the treated group received orally 25 mg of various copper coordination compounds of my invention (1 ml saline solution - 1 drop Tween 80) three times daily.", "The results of this test, using the ulcer index as found in Robert, A. et al, Proc.", "Soc.", "Expt'l.", "Biol.", "99, pp. 443-47, "Ulcergenic Property of Steroids"", "(1958) (incorporated by reference herein) are included in Tables III and IV.", "In addition to the foregoing anti-inflammatory and anti-ulcer tests, several LD 50 tests [performed in accordance with Miller et al, Proceed.", "of The Society of Expt'l.", "Medicine, 57, p. 261 (1944)] were performed with some copper coordination compounds and compared to cupric acetate, aspirin and tpan.", "The results are set forth in Table II along with TI data which is the ratio of the lethal dose to effective dose.", "The following surprising results may be gleaned quickly by reviewing the results set forth in Tables I-IV.", "(1) A marked increase in anti-inflammatory activity was observed for most of the compounds of the present invention as compared to prior art compounds.", "(2) Many parent compounds used to prepare the copper coordination compounds possess no anti-inflammatory activity while their copper coordination compounds did.", "(3) The LD 50 of the copper coordination compounds of my invention were substantially less than prior art anti-inflammatory agents.", "(4) While all known prior art compounds useful as anti-inflammatory agents are known ulcergenic componds, my copper coordination compounds displayed anti-ulcer activity.", "Upon further and more extensive study of the results the following observations are of interest to those skilled in the art.", "From a review of the Tables it can be noted that activity in the various test models is apparently not a function of the amount of the percent of copper present in the copper coordination compound.", "For example, activity in the Shay Rat Anti-Ulcer activity model was displayed in compounds at similar dosages having about 7.7% be weight copper and in compounds having about 19% by weight copper.", "While examples 1, 8, 16, 30 and 41 showed no anti-inflammatory activity at the initial screening tests and using only one test model, it is believed that they would display anti-inflammatory activity under other conditions.", "From the foregoing description it can be noted that all of the compounds of the present invention have the formula Cu y X n wherein y and n are numerals and wherein x is derived from at least one group of coordinating elements.", "By group of coordinating elements I mean a group of elements which are not attached to each other in a cyclic manner.", "The coordinating compounds may contain within them carbocyclic or heterocyclic structural components.", "By coordinating elements I mean elements which contribute electrons to form a covalent bond with copper, which may have a valence state of +1 or +2.", "In most instances, such coordinating elements are selected from the group of oxygen, nitrogen, halogen and sulfur.", "In most instances my copper coordination compounds have the formula Cu 1y X 2n .", "In this case the coordinating groups may be the same or different.", "Another class of my copper coordination compounds has the formula Cu 3y X 2n and the coordinating groups may be the same or different.", "A still further class has the formula Cu 2y X 4n and the coordinating groups may be the same or different.", "From the foregoing description it will also be understood that in the treatment of inflammation (arthritis) and gastrointestinal ulcers in animals my compounds may be administered in customary ways.", "While the dosages recommended herein for use are preferred, other dosages may also provide beneficial results.", "Referring now to Table V, which sets out some of the structural formulae of my copper coordination compounds, the following is given in explanation thereof.", "Example 1 has the structure d when the ligand is derived from L-tryptophan (a) and x is a amino.", "Example 2 has the structure d when the ligand is derived from D-tryptophan (a) and x is amino.", "Example 16 has the structure d when the ligand is derived from D,L-tryptophan (a) and x is amino.", "Example 3 has the structure d when the ligand is derived from anthranilic acid (b) and x is o-amino.", "Example 4 has the structure d when the ligand is derived from 3,5-diisopropylsalicyclic acid (c) and x is o-hydroxyl.", "TABLE I__________________________________________________________________________THE ANTI-INFLAMMATORY ACTIVITIES OF SOME COPPER COORDINATIONCOMPOUNDS COMPARED WITH SOME OF THEIR PARENT COMPOUNDS CARRA- % POTENCY GEENIN COMPAREDEX- FOOT COTTON WAD WITH HYDRO- %AMPLECOMPOUND EDEMA GRANULOMA POLYARTHRITIS CORTISONE COPPER__________________________________________________________________________cupric acetate A@1 mg SC I@20 mg SC I@5 mg SC 340 31.8L-tryptophan I@25 mg SC NT NT1 Cu(II)(L-tryptophan).", "sub[.", "].2 I@25 mg SC I@20 mg SC NT 13.5D-tryptophan I@25 mg SC NT NT2 Cu(II)(D-tryptophan).", "sub[.", "].2 A@25 mg SC I@20 mg SC NT 13.5anthranilic acid I@25 mg SC NT I@5 mg SC3 Cu(II)(anthranilate).", "sub.", "2 A@1 mg SC A@5 mg SC [email protected] mg SC(+25) 60 18.93,5-dips acid I@25 mg SC NT I@5 mg SC4 Cu(II)(3,5-dips).", "sub.", "2 A@1 mg SC A@1 mg SC [email protected] mg SC(+24) 50 12.5aspirin A@8 mg SC A@40 mg IG A@1 mg SC(+5) 65 Cu(II).", "sub[.", "].2 (aspirinate).", "sub[.", "].4 A@1 mg SC A@2 mg SC [email protected] mg SC(+27) 130 15.0tpan A@5 mg IG A@5 mg IG A@1 mg IG(+5) 316 Cu(II).", "sub.", "n (tpan).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub.", "n A@1 mg SC A@2 mg SC [email protected] mg SC(+18) 180 10.1D-penicillamine I@25 mg SC I@20 mg SC I@5 mg SC7 Cu(I).", "sub.", "n D-pen(H.", "sub[.", "].2 O).", "sub[.", "].1.5n A@1 mg SC A@2 mg SC NT 26.78 Cu(II).", "sub.", "n (D-pen).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub[.", "].2n I@25 mg SC NT NT 16.19 Cu(II).", "sub.", "n (D-pen disulfide).", "sub.", "n (H.", "sub[.", "].2 O).", "sub[.", "].3n A@1 mg SC A@5 mg SC A@5 mg SC(+18) 15.4pat I@25 mg SC A@20 mg IG A@20 mg IG(+5)10 Cu(II).", "sub.", "n (pat).", "sub.", "n (acetate).", "sub[.", "].2n A@1 mg SC A@5 mg SC A@5 mg SC(+5) 18.511 Cu(II).", "sub.", "n (pat).", "sub[.", "].2n (HCl).", "sub.", "2n A@2 mg SC A@2 mg SC NT 13.9__________________________________________________________________________ TABLE II______________________________________THE LD.", "sub[.", "].50 AND CALCULATED TI DATAFOR SOME COPPER COORDINATION COMPOUNDSEX- TIAMPLE COMPOUND LD.", "sub[.", "].50 CFE PA______________________________________ cupric acetate 350 mpk SC 70 03 Cu(II)(anthranilate).", "sub.", "2 750 ± 106 mpk 150 750 SC4 Cu(II)(3,5-dips).", "sub.", "2 240 ± 33 mpk 48 240 SC aspirin 1500 mpk IG 790 mpk RT5 Cu(II).", "sub[.", "].2 (aspirinate).", "sub[.", "].4 760 ± 100 mpk 150 760 SC tpan 370 ± 25 mpk 15 74 IG6 Cu(II).", "sub.", "n (tpan).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub.", "n 650 ± 80 mpk 130 650 SC______________________________________ TABLE III__________________________________________________________________________A COMPARISON OF THE ANTI-ULCER ACTIVITIES AMONG THECOPPER COORDINATION COMPOUNDS OFTABLE I AND SOME OF THEIR PARENT COMPOUNDS SHAY RAT: CORTICOID INDUCED: ANTI-ULCER ANTI-ULCEREXAMPLE COMPOUND ACTIVITY ACTIVITY__________________________________________________________________________ Cu(II).", "sub[.", "].2 (acetate).", "sub[.", "].4 (H.", "sub[.", "].2 O).", "sub[.", "].2 A@50 mg IG NT1 Cu(II)(L-tryptophan).", "sub.", "2 [email protected] mg IG A@25 mg IG2 (Cu(II)(D-tryptophan).", "sub[.", "].2 A@1 mg IG NT D-tryptophan I@50 mg IG NT3 Cu(II)(anthranilate).", "sub[.", "].2 A@1 mg IG A@25 mg IG anthranilic acid A@50 mg IG NT4 Cu(II)(3,5-dips).", "sub.", "2 [email protected] mg IG A@25 mg IG5 Cu(II).", "sub[.", "].2 (aspirinate).", "sub[.", "].4 [email protected] mg IG NT aspirin A@50 mg IG NT6 Cu(II).", "sub.", "n (tpan).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub.", "n A@1 mg IG NT tpan I@50 mg IG NT7 Cu(I).", "sub.", "n D-pen(H.", "sub[.", "].2 O).", "sub[.", "].1.5n NT NT8 Cu(II).", "sub.", "n (D-pen).", "sub[.", "].2n (H.", "sub[.", "].2 0).", "sub[.", "].2n A@1 mg IG NT9 Cu(II).", "sub.", "n (D-pen disulfide).", "sub.", "n (H.", "sub[.", "].2 O).", "sub[.", "].3n A@1 mg IG NT10 Cu(II).", "sub.", "n (pat).", "sub.", "n (acetate).", "sub[.", "].2n A@1 mg IG NT11 Cu(II).", "sub.", "n (pat).", "sub[.", "].2n (HCl).", "sub[.", "].2n A@1 mg IG NT__________________________________________________________________________ TABLE IV__________________________________________________________________________THE ANTI-INFLAMMATORY AND ANTI-ULCER ACTIVITIES OF SOME ADDITIONAL COPPERCOORDINATIONCOMPOUNDS COMPARED TO SOME OF THEIR PARENT COMPOUNDS Shay Rat: Carrageenin Cotton Wad Percent Anti-UlcerEx.", "Compound Foot Edema Granuloma Polyarthritis Copper Activity__________________________________________________________________________ Amino Acids Cu(II).", "sub.", "n (D-aspartate).", "sub.", "n (H.", "sub[.", "].2 O).", "sub[.", "].3.5n A@1 mg SC A@2 mg SC NT 32.6 [email protected] mg IG Cu(II).", "sub.", "n (L-aspartate).", "sub.", "n (H.", "sub.", "2 O).", "sub[.", "].3.5n A@1 mg SC NT NT 32.6 [email protected] mg IG Cu(II).", "sub.", "n (L-lysinate).", "sub.", "n (Cl).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub.", "n [email protected] mg SC A@2 mg SC NT 21.9 A@10 mg IG Cu(II).", "sub.", "n (L-lysinate).", "sub[.", "].2n (Cl).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub.", "n A@1 mg SC NT NT 14.3 NT16 Cu(II)(D,L-tryptophan).", "sub.", "2 I@25 mg SC NT NT 13.5 A@1 mg IG17 Cu(II).", "sub.", "n (ε-aminocaproate).", "sub.", "n (Cl).", "sub[.", "].1.5n (CH.", "sub[.", "].3 OG).", "sub[.", "].0.5n NT NT NT 24.0 [email protected] mg IG18 Cu(II).", "sub.", "n (ε-aminocaproate).", "sub.", "n (Cl).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub[.", "].0.5n NT NT NT 23.2 A@1 mg IG* Amines19 Cu(II).", "sub[.", "].2 (pyridine).", "sub[.", "].2 (acetate).", "sub[.", "].4 A@2 mg SC NT NT 24.4 [email protected] mg IG20 Cu(II) (pyridine).", "sub[.", "].2 (Cl).", "sub[.", "].2 A@1 mg SC NT NT 21.6 A@10 mg IG21 Cu(II)(morpholine).", "sub[.", "].2 (Cl.", "sub[.", "].2) (HCl).", "sub[.", "].2 [email protected] mg SC A@5 mg SC NT 16.6 NT22 Cu(II).", "sub.", "n (histamine).", "sub.", "n (Cl).", "sub[.", "].2n (HCl).", "sub[.", "].2n NT NT NT 20.0 A@ 10 mg IG* Salicylates Cu(II).", "sub[.", "].2 (salicylate).", "sub[.", "].4 (Na).", "sub[.", "].4 A@2 mg SC A@2 mg SC NT 17.8 NT Cu(II).", "sub.", "n (salicylate).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub[.", "].4n A@1 mg SC A@5 mg SC NT 15.5 A@1 mg IG Heterocyclic Carboxylic Acids25 Cu(II).", "sub[.", "].2n (nicotinate).", "sub[.", "].4n (H.", "sub[.", "].2 O).", "sub[.", "].3n NT NT NT 19.0 A@1 mg IG26 Cu(II).", "sub.", "n (1-carboxyisoquinoline).", "sub[.", "].2n A@5 mg SC A@5 mg SC NT 15.6 A@50 mg IG27 Cu(II).", "sub.", "n (2-phenyl-4-carboxyisoquinoline).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub[.", "].2n .", "NT NT NT 10.6 A@1 mg IG*28 Cu(II).", "sub.", "n (2-carboxyindole).", "sub[.", "].3n (acetate).", "sub.", "n (H.", "sub[.", "].2 O).", "sub[.", "].0.5n A@1 mg SC A@2 mg SC NT 16.5 [email protected] mg IG29 Cu(II).", "sub.", "n (2-carboxyindole).", "sub[.", "].3n (acetate).", "sub.", "n (H.", "sub[.", "].2 O).", "sub[.", "].3.5n NT NT NT 15.4 A@1 mg IG*30 Cu(II).", "sub.", "n (cp-tcca).", "sub[.", "].2n (H.", "sub[.", "].2 0).", "sub[.", "].2n I@25 mg SC NT NT 8.8 A@1 mg IG31 Cu(II).", "sub.", "n (tcca).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub[.", "].2.5n I@5 mg SC NT NT 11.8 A@50 mg IG Corticoids hydrocortisone-21-phosphate(Na).", "sub[.", "].2 NT NT I@1 mg SC** I@10 mg IG**32 Cu(II).", "sub[.", "].3n (HC-21-phosphate).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub[.", "].9n A@2 mg SC A@5 mg SC A@1 mg SC 15.4 A@5 mg IG (+7)**33 Cu(II).", "sub[.", "].3n (HC-21-phosphate).", "sub[.", "].2n (H.", "sub[.", "].2 0).", "sub[.", "].7n NT NT I@1 mg SC** 15.9 [email protected] mg IG hydrocortisone-21-hemisuccinate NT NT A@1 mg SC I@10 mg IG** (+7)**34 Cu(II).", "sub[.", "].2n (HC-21-hemisuccinate).", "sub[.", "].4n (H.", "sub[.", "].2 0).", "sub[.", "].6n [Green] A@2 mg SC A@5 mg SC A@1 mg SC 6.1 A@5 mg IG (+7)**35 Cu(II).", "sub[.", "].2.5n (HC-21-hemisuccinate).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub[.", "].7n A@2 mg SC A@1 mg SC A@1 mg SC 13.5 A@10 mg IG* (+11)** Dexamethasone-21-phosphate(Na).", "sub[.", "].2 NT NT NT NT36 Cu(II).", "sub[.", "].3n (dexamethasone-21-phosphate).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub[.", "].7n NT NT NT 15 A@5 mg IG37 Cu(II).", "sub[.", "].3n (dexamethasone-21-phosphate).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub[.", "].1.5n NT NT NT 16 A@5 mg IG Arylacetic Acids38 Cu(II).", "sub[.", "].2n [1-(p-chlorobenzoyl)-5-methoxy-2- methylindole-3-acetate].", "sub[.", "].4n (H.", "sub[.", "].2 O).", "sub[.", "].4n NT NT NT 7.8 A@10 mg IG*39 Cu(II).", "sub[.", "].2n [1-(p-chlorobenzoyl)-5-methoxy-2- methylindole-3-acetate].", "sub[.", "].4n (CH.", "sub[.", "].3 COCH.", "sub[.", "].3).", "sub[.", "].2n NT NT NT 7.7 A@1 mg IG Pyrazolidinedione40 Cu(II).", "sub.", "n (4-n-butyl-1,2-diphenyl-3,5- pyrazolidinedione).", "sub[.", "].2n NT NT NT 11.8 A@10 mg IG Steroidal Acids41 Cu(II).", "sub.", "n (17-hydroxy-3-oxo-17 -pregn-4,6-diene-21- carboxalate).", "sub[.", "].2n (H.", "sub[.", "].2 O).", "sub[.", "].2n I@5 mg SC** NT I@5 mg SC** 7.8 A@5 mg__________________________________________________________________________ IG *Not tested at lower dose **Only dose tested NT = Not Tested TABLE V______________________________________ ##STR1## a ##STR2## b ##STR3## c ##STR4## dEXAMPLES 1, 2, 16;", "3 and 4.", "##STR5## EXAMPLE 5 ##STR6## EXAMPLE 19 ##STR7## EXAMPLE 20 ##STR8## EXAMPLE 21 ##STR9## EXAMPLE 23 ##STR10## EXAMPLE 24______________________________________" ]
FIELD OF THE INVENTION The present invention relates to an apparatus for regularly collecting pipes, rods and similar objects. BACKGROUND OF THE INVENTION An apparatus is already known in which a transfer rail is connected with a U-shaped rigid rack at the tip thereof, to a receiving rack; pipes or similar objects are transfered from the rail down into the receiving rack. The known apparatus has some defects, for example, a loud noise is made when the pipes collide with each other. The surfaces of the pipes are also injured as the result of the collision. Another kind of apparatus has been developed in order to eliminate these defects. An inclining flexible belt is substituted in place of the above-described U-shaped rack. The belt, in the latter apparatus, is positioned at the end of the transfer rail and receives the pipes continuously one by one into its hollow space. The receiving space become gradually bigger and deeper as the belt is pulled downward by the weight of the pipes; the greater the number of pipes, the further the belt is pulled downward, until some limit is reached. The pipes received onto the belt stand in a row until the last pipe is flush with the transfer rail. Succeeding pipes entering into the space will fiercely roll down over the row of the pipes already received, thereby making loud noise and damaging the surface of the pipes. In addition, the pipes, are so irregularly collected into the belt space that they can not be easily bundled and lifted upward. SUMMARY OF THE INVENTION The present invention offers an apparatus which collects pipes, rods and similar articles parallel to each other, and which includes a transfer rail and a pair of roller chains supported by a device comprising a pair of feed sprockets, a pair of take-up sprockets, a pair of swing sprockets and a pair of front and rear props. The feed sprockets are rotatably fixed on the upper portion of the front props. The take-up sprockets are rotatably fixed on the upper portion of the rear props. The feed sprockets drive the roller chains faster than the take-up sprockets. Thus, the roller chains between the feed sprockets and the take-up sprockets will expand downward by the swinging motion of the swing sprockets. The section of the roller chains between the feed sprockets and take-up sprockets receives the pipes. The apparatus in accordance with the present invention can receive pipes or similar articles smoothly and in regular sequence. The pipes are regularly collected to form an equilateral polygon when viewed from the side. The structure of the apparatus will be understood and certain of its advantages more fully appreciated from the detailed description which follows, read in connection with the accompanying drawings illustrating practical embodiments of the apparatus in which the invention may be practiced. IN THE DRAWINGS BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side plan view of a first embodiment of the invention; FIG. 2 is a top plan view of the first embodiment of the invention; FIGS. 3,4,5 and 6 are diagrammatic side plan views of the first embodiment of the invention showing the process of collecting the pipes; FIG. 7 is a diagrammatic side plan view showing the oil-hydraulic system in said first embodiment of the invention; and FIG. 8 is a diagrammatic side plan view of a second embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 and FIG. 2, 1 and 2 show, respectively, the front and rear props located at certain intervals. The rear props 2 are higher than the front props 1. The right and left sides of the apparatus are equipped with props 1 and 2. The top end of the front props 1 are connected to inclined transfer rails 3 and the lowest end thereof. The rear props 2 which are elbow-shaped and project backward, are fixed to a shaft 6. The shaft 6 is rotatable within certain angular limits and is supported by bearings 5 fixed to the lower surface of the bottom frame 4. Levers 7 are also fixed at one end to the shaft 6, and connected at their other end to fluid-cylinders 8. Thus, the above-mentioned rear props 2 can be caused to swing forward and backward by the levers 7, driven by the fluid-cylinders 8. Each feed sprocket 9 is fixed revolvably upon the top of a bracket 10, attached to the upper portion of the props 1. The sprockets 9 stand close to the tip ends of the transfer rails 3. The symbol 11 indicates take-up sprockets fixed revolvably upon the top of the rear props 2. The take-up sprockets 11 and the feed sprockets 9 are idle wheels of the same diameter. The symbol 12 indicates endless flexible strips of roller chains. The roller chains 12 are mounted on the feed sprockets 9, the take-up sprockets 11, intermediate sprockets 13, 14, driving sprockets 15, 16 and swing sprockets 17. The roller chains 12 rotate in the direction indicated by the arrows in FIG. 1. Intermediate sprockets 13 are fixed to the lower portion of the rear props 2, and the other intermediate sprockets 14 are fixed to the rear bottom portion of frame bases 18. The driving sprockets 15 are fixed to a shaft 44, supported rotatably by the rear end portions of the bases 18, half way up the bases 18. The other driving sprockets 16 are fixed to a shaft 45 rotatably supported upon the brackets 10, at the lower portions thereof. Sprockets 13-17 have the same diameter as the foregoing sprockets 9 and 11. The swing sprockets 17 are freely rotatably fixed upon the top of levers 20 supported by the frame bases 18. The levers 20 are caused to swing forward and backward by fluid-cylinders 21 within certain angular limits. The symbol 22 indicates a cyclo-reduction gear driven by an oil-hydraulic motor 23. A pinion 24, installed onto the output shaft of the cyclo-reduction gear 22, drives, via a chain 54, a sprocket 25, fixed to the above-mentioned shaft 44, holding the driving sprockets 15. The pinion 24 further drives, via chain 54, and large sprockets 26, sprockets 27 which are fixed to the shafts 45, holding the driving sprockets 16. In this way, the roller chains 12 are driven in the direction indicated by the arrow in FIG. 1. It will be understood from the above description that the driving sprockets 16 are devised so as to rotate faster than the driving sprockets 15. The diameter of the sprockets 26 is larger than that of the sprockets 27, and the sprockets 26 and 27 are connected respectively to driving sprockets 15 and 16 through respective common shafts 44 and 45. Therefore, the speed of the part of the roller chains 12 engaging feed sprockets 9 under the direct influence of the driving sprockets 16, is greater than the speed of that part of the same roller chains engaging the take up sprockets 11, under the indirect influence of the driving sprockets 15 through the intermediate sprockets 14 and 13. Because of the difference in the speeds of various parts of roller chains 12, the roller chains 12 will hang down between sprockets 9 and 11. The symbol 28 indicates stoppers. The bottom ends of the stoppers 28 are fixed to a shaft 31, supported rotatably with bearings 30. The bearings 30 are attached to the lower surfaces of frame tops 29, said frame tops 29 supporting the transfer rails 3 at the upper surfaces thereof. The symbol 32 indicates levers whose top ends are fixed to the shafts 31, and whose bottom ends are joined to fluid-cylinders 33. Accordingly, when the fluid cylinders 33 are actuated the top portions of the stoppers 28 are raised above the transfer rails 3 and then brought down below the transfer rails 3. A roller conveyor 34 is positioned near the entrance of the transfer rails 3 at right angles thereto. The symbol 35 indicates kickers supplying the pipes or similar articles to the rails 3 from the said conveyor 34. The operation of the embodiment having the construction described above is explained as follows. The rear props 2 are tilted slightly forward by the motion of the fluid-cylinders 8. The fluid-cylinders 21 are then activated and the swing sprockets 17 are shifted to their most forward position by the levers 20. The roller chains 12 are consequently stretched and straightened between the feed sprockets 9 and the take-up sprockets 11. Further, the stoppers 28 are lifted above the transfer rails 3 by the motion of the fluid-cylinders 33, acting through the levers 32. In the above state of the apparatus, the pipes or similar articles on the roller conveyor 34 are then supplied in order, onto the transfer rails 3 by the kickers 35. Those pipes will roll down toward the stoppers 28 and rest on transfer rails 3, thereupon lying in a parallel row. Next, the stoppers 28 are retracted to put the forefront pipe "a" in contact with the roller chains 12 supported under tension by the feed sprockets 9 and the take-up sprockets 11, as shown in FIG. 3. The cyclo-reduction gear 22 is now put into operation to drive-pinion 24. The pinion 24 drives the sprocket 25 by means of a chain 54. The large sprockets 26, fixed to the same shaft as said sprocket 25, will drive, in turn, the sprockets 27. The driving sprockets 15 are fixed to the same shaft 44 as sprockets 26, and the driving sprockets 16 are fixed to the same shaft 45 as sprockets 27. Thus, driving sprockets 15 and 16 drive the roller chains 12 in the direction indicated by the arrows in FIG. 1. It will be here noted that the driving sprockets 16 make more revolutions per minute than driving sprockets 15, because of the larger diameter of the sprockets 26 compared with that of the sprockets 27. As a result, the feed sprockets 9 driven by the sprockets 16 will make more revolutions than the take-up sprockets 11 driven by the sprockets 15 through the sprockets 14 and 13. Consequently, the length of the roller chains 12 fed by the feed sprockets 9 is longer than that taken up by the take-up sprockets 11. The roller chains 12 will thus be loosened between said feed sprockets 9 and take-up sprockets 11. At the same time, the roller chains 12 are stretched at the front (entrance) side of the feed sprockets 9. The swing sprockets 17 will be subsequently drawn toward the feed sprockets 9 by the power of the fluid-cylinders 21, stressing the roller chains 12 as shown in FIG. 7. In this way, the roller chains 12 will hang gradually deeper and deeper between the said feed sprockets 9 and take-up 11, moving toward the latter sprockets. The pipes are delivered one by one to roller chains 12, and are moved along with the roller chains 12. The pipes are received into the space made by the roller chains 12 and bundled up thereby into a bundle in the shape of regular polygon when viewed from the side shown in FIGS. 4,5 and 6. The horizontal distance "A" between the feed sprockets 9 and the take-up sprockets 11 should be preferably increased when the number of pipes to be received is increased. As a result of experiments, the relation shown in Table 1 between said distance "A" and the number of the pipes to be received, was found to give good performance by the apparatus; Table 1______________________________________Number of pipes or Horizontal distance "A" betweenthe like received the feed and take-up sprockets______________________________________0˜7 2D 8˜19 3D20˜37 4D______________________________________ where "D" signifies the diameter of the pipes or similar articles. In regard to the ratio of the peripheral velocity of the feed sprockets 9 to that of the take-up sprockets 11, it was found that the ratio should be decreased when the number of pipes or similar articles to be received increases. According to experimental results, the relation between said parameters as shown in Table 2 was found to be desirable for satisfactory performance of the apparatus; Table 2______________________________________ Ratio of the peripheral velocityNumber of pipes of the feed sprockets 9 to that ofreceived the take-up sprockets 11______________________________________ ˜9 2:119˜37 1.75:137˜61 1.5:1______________________________________ where the ratio 1.66:1 is taken as an average value. After the predetermined number of the pipes or similar articles on the transfer rails 3 have been received into the hollow space formed by the roller chains 12, the fluid-cylinders 33 are then operated to raise up the stoppers 28 above the rails 3. The stoppers 28 be held there until the next cycle will starts. The cyclo-reducing gear 22 is simultaneously stopped to rest the roller chains 12. The fluid-cylinders 8 are next put into operation to rotate the rear props 2 backward. The distance between the feed sprockets 9 and take-up sprockets 11 is thus so enlarged that the received pipes or similar articles may be easily taken out from the above mentioned space. In addition to the above operations, the fluid cylinders 21 are then activated bringing the swing sprockets 17 forward by the motion of the levers 20; the roller chains 12 are simultaneously circulated in the reverse direction by the reverse revolution of the feed sprockets 9, and the take-up sprockets 11. The roller chains 12 are in this way stretched again between the feed sprockets 9 and the take-up sprockets 11. The roller chains 12 are used as endless flexible strips in the embodiment described above. However, the present invention is not restricted to using roller chains 12 to function as flexible strips. A kind of timing belt, for example, can be adoped. In addition, ordinary belts might be used as shown in FIG. 8. In this said embodiment, an endless ordinary belt 12' is mounted over feed wheels 9', take-up wheels 11', lower intermediate wheels 13', swing wheels 17' and driving wheels 16'. The swing wheels 17' are capable of moving forward and backward under the action of the piston rods of the fluid-cylinders 21. Accordingly, said swing wheels 17' stretch up or loosen the belt 12' between the feed wheels 9' and the take-up wheels 11', in the same manner as in the first embodiment. When occasion demands, the apparatus is equipped with a pinch wheel 47 engaging the driving wheels 16'. The pinch wheel 47 thrusts the belt 12' upon the wheel 16' giving a stronger tension to the portion of the belt 12' and not between the wheels 9' and 11'. As described above, the structure of the apparatus in the present invention is summarized as follows. The rear props 2 are located to the rear of the front props 1, said rear props 2 being higher than said front props 2. The right and left sides of the apparatus are equipped with front props 1 and rear props 2; feed wheels or sprockets 9, 9' and the take-up wheels or sprockets 11, 11' are rotatably supported, respectively on the tops of said front props 1 and rear props 2; the roller chains 12 or ordinary belts 12' are mounted onto said feed and take-up wheels or sprockets 9,11 or 9', 11' and the swing wheels 17 or swing sprockets 17' moved forward, to the feed wheels 9' or feed sprockets 9 and backward; the driving mechanism for said roller chains 12 or belts 12' circulating said roller chains 12 or belt 12' from the feed wheels 9' or feed sprockets 9 to the take-up wheels 11' or take-up sprockets 11; said driving mechanism also causes the feed wheels 9' or feed sprockets 9 to be rotated with higher peripheral velocity than the take-up wheels 11 or take-up sprockets 11. As a result of the operation of the above-mentioned structure, said roller chains 12 or belts 12', receiving the pipes or similar articles, move in the direction from the feed sprockets 9 or feed wheels 9' to the take-up wheels 11' or take-up sprockets 11, and are simultaneously pulled down gradually, between the feed sprockets 9 or feed wheels 9' and take-up wheels 11' or take-up sprockets 11. The many advantages over prior conventional apparatuses include: the pipes or similar articles are quietly and softly received without any harsh collision thereamong; the pipes or similar articles already received move together with the roller chains 12 or belts 12', thus smoothing the way for the next pipe or similar articles; the pipes or the like are protected from damages and injuries; and the pipes or similar articles are automatically gathered to make a preliminary polygonal assemblies for easier succeeding operations, such as tying, hoisting and carrying out.
An apparatus which collects pipes, rods and similar objects parallel one another, to form a bundle. The apparatus includes at least one pair of transfer rails from which the pipes are transferred to a pair of roller chains where the pipes are collected. The roller chains are mounted on driving sprockets, swing sprockets, feed sprockets and take-up sprockets. The velocity of the take-up sprockets is lower than the velocity of the feed sprockets, causing the roller chain to sag therebetween, creating a space to collect the pipes.
Briefly describe the main idea outlined in the provided context.
[ "FIELD OF THE INVENTION The present invention relates to an apparatus for regularly collecting pipes, rods and similar objects.", "BACKGROUND OF THE INVENTION An apparatus is already known in which a transfer rail is connected with a U-shaped rigid rack at the tip thereof, to a receiving rack;", "pipes or similar objects are transfered from the rail down into the receiving rack.", "The known apparatus has some defects, for example, a loud noise is made when the pipes collide with each other.", "The surfaces of the pipes are also injured as the result of the collision.", "Another kind of apparatus has been developed in order to eliminate these defects.", "An inclining flexible belt is substituted in place of the above-described U-shaped rack.", "The belt, in the latter apparatus, is positioned at the end of the transfer rail and receives the pipes continuously one by one into its hollow space.", "The receiving space become gradually bigger and deeper as the belt is pulled downward by the weight of the pipes;", "the greater the number of pipes, the further the belt is pulled downward, until some limit is reached.", "The pipes received onto the belt stand in a row until the last pipe is flush with the transfer rail.", "Succeeding pipes entering into the space will fiercely roll down over the row of the pipes already received, thereby making loud noise and damaging the surface of the pipes.", "In addition, the pipes, are so irregularly collected into the belt space that they can not be easily bundled and lifted upward.", "SUMMARY OF THE INVENTION The present invention offers an apparatus which collects pipes, rods and similar articles parallel to each other, and which includes a transfer rail and a pair of roller chains supported by a device comprising a pair of feed sprockets, a pair of take-up sprockets, a pair of swing sprockets and a pair of front and rear props.", "The feed sprockets are rotatably fixed on the upper portion of the front props.", "The take-up sprockets are rotatably fixed on the upper portion of the rear props.", "The feed sprockets drive the roller chains faster than the take-up sprockets.", "Thus, the roller chains between the feed sprockets and the take-up sprockets will expand downward by the swinging motion of the swing sprockets.", "The section of the roller chains between the feed sprockets and take-up sprockets receives the pipes.", "The apparatus in accordance with the present invention can receive pipes or similar articles smoothly and in regular sequence.", "The pipes are regularly collected to form an equilateral polygon when viewed from the side.", "The structure of the apparatus will be understood and certain of its advantages more fully appreciated from the detailed description which follows, read in connection with the accompanying drawings illustrating practical embodiments of the apparatus in which the invention may be practiced.", "IN THE DRAWINGS BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side plan view of a first embodiment of the invention;", "FIG. 2 is a top plan view of the first embodiment of the invention;", "FIGS. 3,4,5 and 6 are diagrammatic side plan views of the first embodiment of the invention showing the process of collecting the pipes;", "FIG. 7 is a diagrammatic side plan view showing the oil-hydraulic system in said first embodiment of the invention;", "and FIG. 8 is a diagrammatic side plan view of a second embodiment of the invention.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 and FIG. 2, 1 and 2 show, respectively, the front and rear props located at certain intervals.", "The rear props 2 are higher than the front props 1.", "The right and left sides of the apparatus are equipped with props 1 and 2.", "The top end of the front props 1 are connected to inclined transfer rails 3 and the lowest end thereof.", "The rear props 2 which are elbow-shaped and project backward, are fixed to a shaft 6.", "The shaft 6 is rotatable within certain angular limits and is supported by bearings 5 fixed to the lower surface of the bottom frame 4.", "Levers 7 are also fixed at one end to the shaft 6, and connected at their other end to fluid-cylinders 8.", "Thus, the above-mentioned rear props 2 can be caused to swing forward and backward by the levers 7, driven by the fluid-cylinders 8.", "Each feed sprocket 9 is fixed revolvably upon the top of a bracket 10, attached to the upper portion of the props 1.", "The sprockets 9 stand close to the tip ends of the transfer rails 3.", "The symbol 11 indicates take-up sprockets fixed revolvably upon the top of the rear props 2.", "The take-up sprockets 11 and the feed sprockets 9 are idle wheels of the same diameter.", "The symbol 12 indicates endless flexible strips of roller chains.", "The roller chains 12 are mounted on the feed sprockets 9, the take-up sprockets 11, intermediate sprockets 13, 14, driving sprockets 15, 16 and swing sprockets 17.", "The roller chains 12 rotate in the direction indicated by the arrows in FIG. 1. Intermediate sprockets 13 are fixed to the lower portion of the rear props 2, and the other intermediate sprockets 14 are fixed to the rear bottom portion of frame bases 18.", "The driving sprockets 15 are fixed to a shaft 44, supported rotatably by the rear end portions of the bases 18, half way up the bases 18.", "The other driving sprockets 16 are fixed to a shaft 45 rotatably supported upon the brackets 10, at the lower portions thereof.", "Sprockets 13-17 have the same diameter as the foregoing sprockets 9 and 11.", "The swing sprockets 17 are freely rotatably fixed upon the top of levers 20 supported by the frame bases 18.", "The levers 20 are caused to swing forward and backward by fluid-cylinders 21 within certain angular limits.", "The symbol 22 indicates a cyclo-reduction gear driven by an oil-hydraulic motor 23.", "A pinion 24, installed onto the output shaft of the cyclo-reduction gear 22, drives, via a chain 54, a sprocket 25, fixed to the above-mentioned shaft 44, holding the driving sprockets 15.", "The pinion 24 further drives, via chain 54, and large sprockets 26, sprockets 27 which are fixed to the shafts 45, holding the driving sprockets 16.", "In this way, the roller chains 12 are driven in the direction indicated by the arrow in FIG. 1. It will be understood from the above description that the driving sprockets 16 are devised so as to rotate faster than the driving sprockets 15.", "The diameter of the sprockets 26 is larger than that of the sprockets 27, and the sprockets 26 and 27 are connected respectively to driving sprockets 15 and 16 through respective common shafts 44 and 45.", "Therefore, the speed of the part of the roller chains 12 engaging feed sprockets 9 under the direct influence of the driving sprockets 16, is greater than the speed of that part of the same roller chains engaging the take up sprockets 11, under the indirect influence of the driving sprockets 15 through the intermediate sprockets 14 and 13.", "Because of the difference in the speeds of various parts of roller chains 12, the roller chains 12 will hang down between sprockets 9 and 11.", "The symbol 28 indicates stoppers.", "The bottom ends of the stoppers 28 are fixed to a shaft 31, supported rotatably with bearings 30.", "The bearings 30 are attached to the lower surfaces of frame tops 29, said frame tops 29 supporting the transfer rails 3 at the upper surfaces thereof.", "The symbol 32 indicates levers whose top ends are fixed to the shafts 31, and whose bottom ends are joined to fluid-cylinders 33.", "Accordingly, when the fluid cylinders 33 are actuated the top portions of the stoppers 28 are raised above the transfer rails 3 and then brought down below the transfer rails 3.", "A roller conveyor 34 is positioned near the entrance of the transfer rails 3 at right angles thereto.", "The symbol 35 indicates kickers supplying the pipes or similar articles to the rails 3 from the said conveyor 34.", "The operation of the embodiment having the construction described above is explained as follows.", "The rear props 2 are tilted slightly forward by the motion of the fluid-cylinders 8.", "The fluid-cylinders 21 are then activated and the swing sprockets 17 are shifted to their most forward position by the levers 20.", "The roller chains 12 are consequently stretched and straightened between the feed sprockets 9 and the take-up sprockets 11.", "Further, the stoppers 28 are lifted above the transfer rails 3 by the motion of the fluid-cylinders 33, acting through the levers 32.", "In the above state of the apparatus, the pipes or similar articles on the roller conveyor 34 are then supplied in order, onto the transfer rails 3 by the kickers 35.", "Those pipes will roll down toward the stoppers 28 and rest on transfer rails 3, thereupon lying in a parallel row.", "Next, the stoppers 28 are retracted to put the forefront pipe "a"", "in contact with the roller chains 12 supported under tension by the feed sprockets 9 and the take-up sprockets 11, as shown in FIG. 3. The cyclo-reduction gear 22 is now put into operation to drive-pinion 24.", "The pinion 24 drives the sprocket 25 by means of a chain 54.", "The large sprockets 26, fixed to the same shaft as said sprocket 25, will drive, in turn, the sprockets 27.", "The driving sprockets 15 are fixed to the same shaft 44 as sprockets 26, and the driving sprockets 16 are fixed to the same shaft 45 as sprockets 27.", "Thus, driving sprockets 15 and 16 drive the roller chains 12 in the direction indicated by the arrows in FIG. 1. It will be here noted that the driving sprockets 16 make more revolutions per minute than driving sprockets 15, because of the larger diameter of the sprockets 26 compared with that of the sprockets 27.", "As a result, the feed sprockets 9 driven by the sprockets 16 will make more revolutions than the take-up sprockets 11 driven by the sprockets 15 through the sprockets 14 and 13.", "Consequently, the length of the roller chains 12 fed by the feed sprockets 9 is longer than that taken up by the take-up sprockets 11.", "The roller chains 12 will thus be loosened between said feed sprockets 9 and take-up sprockets 11.", "At the same time, the roller chains 12 are stretched at the front (entrance) side of the feed sprockets 9.", "The swing sprockets 17 will be subsequently drawn toward the feed sprockets 9 by the power of the fluid-cylinders 21, stressing the roller chains 12 as shown in FIG. 7. In this way, the roller chains 12 will hang gradually deeper and deeper between the said feed sprockets 9 and take-up 11, moving toward the latter sprockets.", "The pipes are delivered one by one to roller chains 12, and are moved along with the roller chains 12.", "The pipes are received into the space made by the roller chains 12 and bundled up thereby into a bundle in the shape of regular polygon when viewed from the side shown in FIGS. 4,5 and 6.", "The horizontal distance "A"", "between the feed sprockets 9 and the take-up sprockets 11 should be preferably increased when the number of pipes to be received is increased.", "As a result of experiments, the relation shown in Table 1 between said distance "A"", "and the number of the pipes to be received, was found to give good performance by the apparatus;", "Table 1______________________________________Number of pipes or Horizontal distance "A"", "betweenthe like received the feed and take-up sprockets______________________________________0˜7 2D 8˜19 3D20˜37 4D______________________________________ where "D"", "signifies the diameter of the pipes or similar articles.", "In regard to the ratio of the peripheral velocity of the feed sprockets 9 to that of the take-up sprockets 11, it was found that the ratio should be decreased when the number of pipes or similar articles to be received increases.", "According to experimental results, the relation between said parameters as shown in Table 2 was found to be desirable for satisfactory performance of the apparatus;", "Table 2______________________________________ Ratio of the peripheral velocityNumber of pipes of the feed sprockets 9 to that ofreceived the take-up sprockets 11______________________________________ ˜9 2:119˜37 1.75:137˜61 1.5:1______________________________________ where the ratio 1.66:1 is taken as an average value.", "After the predetermined number of the pipes or similar articles on the transfer rails 3 have been received into the hollow space formed by the roller chains 12, the fluid-cylinders 33 are then operated to raise up the stoppers 28 above the rails 3.", "The stoppers 28 be held there until the next cycle will starts.", "The cyclo-reducing gear 22 is simultaneously stopped to rest the roller chains 12.", "The fluid-cylinders 8 are next put into operation to rotate the rear props 2 backward.", "The distance between the feed sprockets 9 and take-up sprockets 11 is thus so enlarged that the received pipes or similar articles may be easily taken out from the above mentioned space.", "In addition to the above operations, the fluid cylinders 21 are then activated bringing the swing sprockets 17 forward by the motion of the levers 20;", "the roller chains 12 are simultaneously circulated in the reverse direction by the reverse revolution of the feed sprockets 9, and the take-up sprockets 11.", "The roller chains 12 are in this way stretched again between the feed sprockets 9 and the take-up sprockets 11.", "The roller chains 12 are used as endless flexible strips in the embodiment described above.", "However, the present invention is not restricted to using roller chains 12 to function as flexible strips.", "A kind of timing belt, for example, can be adoped.", "In addition, ordinary belts might be used as shown in FIG. 8. In this said embodiment, an endless ordinary belt 12'", "is mounted over feed wheels 9', take-up wheels 11', lower intermediate wheels 13', swing wheels 17'", "and driving wheels 16'.", "The swing wheels 17'", "are capable of moving forward and backward under the action of the piston rods of the fluid-cylinders 21.", "Accordingly, said swing wheels 17'", "stretch up or loosen the belt 12'", "between the feed wheels 9'", "and the take-up wheels 11', in the same manner as in the first embodiment.", "When occasion demands, the apparatus is equipped with a pinch wheel 47 engaging the driving wheels 16'.", "The pinch wheel 47 thrusts the belt 12'", "upon the wheel 16'", "giving a stronger tension to the portion of the belt 12'", "and not between the wheels 9'", "and 11'.", "As described above, the structure of the apparatus in the present invention is summarized as follows.", "The rear props 2 are located to the rear of the front props 1, said rear props 2 being higher than said front props 2.", "The right and left sides of the apparatus are equipped with front props 1 and rear props 2;", "feed wheels or sprockets 9, 9'", "and the take-up wheels or sprockets 11, 11'", "are rotatably supported, respectively on the tops of said front props 1 and rear props 2;", "the roller chains 12 or ordinary belts 12'", "are mounted onto said feed and take-up wheels or sprockets 9,11 or 9', 11'", "and the swing wheels 17 or swing sprockets 17'", "moved forward, to the feed wheels 9'", "or feed sprockets 9 and backward;", "the driving mechanism for said roller chains 12 or belts 12'", "circulating said roller chains 12 or belt 12'", "from the feed wheels 9'", "or feed sprockets 9 to the take-up wheels 11'", "or take-up sprockets 11;", "said driving mechanism also causes the feed wheels 9'", "or feed sprockets 9 to be rotated with higher peripheral velocity than the take-up wheels 11 or take-up sprockets 11.", "As a result of the operation of the above-mentioned structure, said roller chains 12 or belts 12', receiving the pipes or similar articles, move in the direction from the feed sprockets 9 or feed wheels 9'", "to the take-up wheels 11'", "or take-up sprockets 11, and are simultaneously pulled down gradually, between the feed sprockets 9 or feed wheels 9'", "and take-up wheels 11'", "or take-up sprockets 11.", "The many advantages over prior conventional apparatuses include: the pipes or similar articles are quietly and softly received without any harsh collision thereamong;", "the pipes or similar articles already received move together with the roller chains 12 or belts 12', thus smoothing the way for the next pipe or similar articles;", "the pipes or the like are protected from damages and injuries;", "and the pipes or similar articles are automatically gathered to make a preliminary polygonal assemblies for easier succeeding operations, such as tying, hoisting and carrying out." ]
[0001] This divisional application claims the benefit of U.S. Continuation application Ser. No. 11/241,231, filed Sep. 30, 2005 which claims priority to U.S. Non-Provisional application Ser. No. 11/122,859; filed May 5, 2005; U.S. Provisional Patent Application Serial No. 60/602,050; filed Aug. 17, 2004, the disclosure of which is incorporated herein by reference. COPYRIGHT STATEMENT [0002] A portion of the disclosure of this document contains material subject to copyright protection. No objection is made to the facsimile reproduction of the patent document or this disclosure as it appears in the Patent and Trademark Office files or records, but any and all rights in the copyright(s) are otherwise reserved. TECHNICAL FIELD [0003] The present invention relates generally to recovering oil and, more particularly, to recovering oil from a byproduct of the dry milling process used to form ethanol. BACKGROUND OF THE INVENTION [0004] Over the past thirty years, significant attention has been given to the production of ethyl alcohol, or “ethanol,” for use as an alternative fuel. Ethanol not only bums cleaner than fossil fuels, but also can be produced using grains such as corn, which are of course renewable resources. At present, approximately sixty-nine “dry milling” plants in the United States produce over two billion gallons of ethanol per year. Additional plants presently under construction are expected to add over four hundred million gallons to this total in an effort to meet the current high demand. [0005] As noted in the foregoing discussion, a popular method of producing ethanol is known as “dry milling,” and in the United States is typically practiced using corn. As is well known in the industry, the dry milling process utilizes the starch in the corn or other grain to produce the ethanol through fermentation, and creates a waste stream comprised of byproducts termed “whole stillage” (which may be further separated into products known as distillers wet grains and “thin stillage”). Despite containing valuable oil, this whole stillage has for the most part been treated as waste and used primarily to supplement animal feed (mostly in the form of distillers dried grains with solubles (DDGS), which is created by evaporating the thin stillage, recombining the resulting concentrate or syrup with the distillers wet grains, and drying the product to have a low moisture content; see, e.g., U.S. Pat. Nos. 5,662,810 and 5,958,233, the disclosures of which are incorporated herein by reference). [0006] Efforts to recover the valuable oil from this byproduct have not been successful in terms of efficiency or economy. For example, one approach involves attempting to separate the oil from the thin stillage before the evaporation stage, such as using a centrifuge. However, spinning the thin stillage at this stage does not produce usable oil, but rather merely creates an undesirable emulsion phase requiring further processing. Moreover, the volume of thin stillage present is generally 2 to 10 times greater than the syrup, which requires considerable capital to purchase the number of centrifuges required. Together, these obstacles make attempts to recover oil from thin stillage highly inefficient and uneconomical. [0007] U.S. Pat. No. 5,250,182 (the disclosure of which is incorporated herein by reference) describes the use of filters for removing substantially all solids and recovering lactic acid and glycerol from the thin stillage without the need for evaporation. Despite eliminating a step in the conventional process, the proposal results in a more complicated arrangement requiring multiple filtration steps. Wholesale elimination of the evaporator in the vast majority of existing plants is also unlikely and otherwise uneconomical. Filters, and especially the microfiltration and ultrafiltration types proposed in this patent, are also susceptible to frequent plugging and thus disadvantageously increase the operating cost. For these reasons, the filtration process proposed in this patent has not gained widespread commercial acceptance. [0008] Accordingly, a need exists for a more efficient and economical manner of recovering oil from a byproduct containing it, such as thin stillage created during the dry milling process used to produce ethanol. SUMMARY OF THE INVENTION [0009] In accordance with one aspect of the invention, a method of processing a concentrated byproduct of a dry milling process for producing ethanol, such as by using corn, is disclosed. In its most basic form, the method comprises recovering oil from the concentrated byproduct. [0010] In one embodiment, the byproduct comprises thin stillage, and the method includes the step of evaporating the thin stillage to form a concentrate. The recovering step may further comprise separating the oil from the concentrate using a disk stack centrifuge. Preferably, the recovering step comprises: (1) providing the concentrated byproduct at a temperature of between about 150 and 212° F. and, most preferably, at a temperature of about 180° F.; and/or (2) providing the concentrated byproduct having a pH of between about 3 and 6 and, most preferably, between about 3.5 and 4.5. Additionally, it is preferred that the concentrated byproduct have a moisture content greater than 15% by weight, more preferably a moisture content greater than 50% and less than 90% and, most preferably, a moisture content between about 60-85%. The step of recovering the oil from the concentrated byproduct produces syrup, and the method may further include the step of recovering oil from the syrup. [0011] In accordance with another aspect of the invention, a more specific method of processing concentrated thin stillage created by a dry milling process for producing ethanol, such as from corn, is disclosed. The method comprises recovering oil from the concentrated thin stillage having a moisture content of less than about 90% by weight. [0012] In one embodiment, the recovering step comprises separating the oil from the concentrate using a disk stack centrifuge. The method may further include the step of drying the concentrate after the removing step. [0013] In accordance with still another aspect of the invention, a method of recovering oil from thin stillage is disclosed. The method comprises evaporating the thin stillage to create a concentrate having a moisture content of greater than 15% by weight and less than about 90% by weight. Oil is then recovered by centrifuging the concentrate, preferably using a disk stack centrifuge. [0014] In accordance with yet another aspect of the invention, a method of processing whole stillage is disclosed. The method comprises recovering thin stillage including oil and solids from the whole stillage, concentrating the thin stillage including the solids, and recovering oil from the concentrate. [0015] In one embodiment, the step of recovering the thin stillage includes using a separator selected from the group consisting of a press, extruder, a decanter centrifuge, and a screen centrifuge. The concentrating step may comprise processing the thin stillage to a temperature of between about 150 and 212° F., a pH of between about 3 and 6, and a moisture content of less than 90%. The step of recovering oil comprises separating the oil from the concentrate using a centrifuge. The recovering and concentrating steps may be performed in a continuous fashion. The method may further include drying the concentrate after recovering oil. [0016] In accordance with a further aspect of the invention, a subsystem for use in a system for producing ethanol by dry milling and creating thin stillage as a byproduct is disclosed. The subsystem comprises an evaporator for evaporating the thin stillage to form a concentrate, and a centrifuge for receiving the concentrate and recovering oil therefrom. Preferably, the concentrate has a moisture content of less than about 90% by weight, and the centrifuge is a disk stack type. [0017] Still a further aspect of the invention is a subsystem for use in a system for producing ethanol by dry milling and creating thin stillage as a byproduct. The subsystem comprises an evaporator for evaporating the thin stillage to form a concentrate and means for recovering oil from the concentrate. In one embodiment, the recovering means comprises a centrifuge and, most preferably, a disk stack centrifuge. [0018] Yet a further aspect of the invention is the combination of a concentrate formed from thin stillage including oil and a centrifuge for removing at least a portion of the oil from the concentrate. Preferably, the concentrate has a moisture content of greater than 15% by weight and less than about 90% by weight, and the centrifuge is a self-cleaning bowl type of disk stack centrifuge, a nozzle bowl disk stack centrifuge, or a horizontal centrifugal decanter BRIEF DESCRIPTION OF THE DRAWINGS [0019] FIG. 1 is a partially schematic flow chart illustrating the processing of co-products formed during the ethanol extraction process; [0020] FIG. 2 is a partially schematic flow chart illustrating the recovery of oil from a syrup formed by evaporating the thin stillage; [0021] FIG. 3 is a schematic view similar to FIG. 1 ; and [0022] FIG. 4 is a schematic view similar to FIG. 2 . DETAILED DESCRIPTION OF THE INVENTION [0023] In accordance with one aspect of the invention, a method recovers oil from a byproduct resulting from the production of ethanol using a dry milling technique (which is extensively described in the above-referenced '182 patent). The byproduct, known as “thin stillage,” is recovered by separating the distillers wet grain from the “whole stillage” leftover after fermentation is complete. As is known in the art, this mechanical separation may be accomplished using a press/extruder, a decanter centrifuge, or a screen centrifuge. Moisture is then removed from the unfiltered thin stillage to create a concentrate or syrup, such as through evaporation. Advantageously, usable oil is then easily recovered from this concentrated form of the byproduct through relatively simple mechanical processing, without the prior need for multiple stages of filtration or other expensive and complicated undertakings. [0024] In one embodiment, oil is recovered from the concentrate by passing it through a centrifuge and, in particular, a disk stack centrifuge (and most preferably a self-cleaning bowl type). Preferably, the concentrate fed to the disk stack centrifuge is at a temperature of between about 150 and 212° F. (and ideally 180° F.) and a pH of between about 3 and 6 (ideally between about 3.5 and 4.5). As a result of the preceding evaporation step, the concentrate has a moisture content of greater than 15% and less than about 90%, more preferably between 30% and about 90%, and ideally about 60-85% by weight. Under these process conditions, the disk stack centrifuge is able to separate the oil in usable form from the concentrate in an efficient and effective manner, despite the relatively high level of solids present (which may be recovered from the centrifuge in a continuous or intermittent fashion, depending on the particular process conditions). [0025] Besides creating usable oil, the concentrate or syrup recovered from the disk stack centrifuge is considered more valuable. This is because the post-evaporation processing to recover or remove the oil improves the efficiency of the drying process used on the combined concentrate syrup and distillers wet grains. A stable, flowable product for supplementing animal feed results, which thus further complements the value of the oil recovered. [0026] Two examples are presented below to demonstrate the efficacy of the above-described method. EXAMPLE 1 [0027] Reference is made to FIGS. 1 and 2 to illustrate schematically a first example demonstrating the efficacy of the present method. FIG. 1 represents one technique for processing whole stillage resulting from dry milling corn to create distillers dried grains with solubles. The whole stillage leftover after deriving the ethanol is mechanically separated into distillers wet grains (approx. 35% solids) and thin stillage (approx. 6.7% solids), such as by using a centrifugal decanter. The thin stillage is then introduced to an evaporator to create a syrup having a moisture content of approximately 80% by weight and about 17% solids by weight. The syrup is then recombined with the distillers wet grains, introduced to a drum dryer, and dried to reduce the overall moisture content to approximately 10% by weight. An estimated total value of the resulting distillers dried grains with solubles is $600.36 per hour. [0028] FIG. 2 represents the inventive method and a related subsystem 10 for implementing it. Initial processing of the whole stillage is done in the same fashion, and the mechanically separated thin stillage is delivered to the evaporator 12 forming part of the subsystem 10 . The resulting concentrate or syrup having a moisture content of approximately 80% by weight and a solids content of approximately 17% by weight is delivered to a disk stack centrifuge 14 , and preferably a “solids ejecting” one, such as an Alfa Laval Model No. AFPX510, AFPX513, or AFPX617 or equivalent device. At an infeed rate of approximately 35 gallons per minute, this centrifuge 14 recovers usable oil at a rate of 538 pounds per hour and produces syrup having a having a moisture content of 82.5% by weight, but with far less oil in view of the preceding recovery step. [0029] Recombining the syrup (which is substantially free of oil) from the centrifuge 14 with the distillers wet grains and drying in a drum dryer 16 to a moisture content of 10% by weight results in a product having a value of $576.46 per hour. However, the 538 pounds per hour of oil recovered has a product value of approximately $102 per hour. Accordingly, the total product value using the inventive method is $678.46 per hour, which is approximately 12% greater than the $600.36 per hour product value resulting from use of the conventional set-up shown in FIG. 1 . Moreover, removal of the majority of the oil before the drying step makes the process more efficient, and results in an estimated energy savings of approximately 10%, or $26.27 per hour. As a result, product value per hour ($678.46) less the estimated dryer operating cost ($236.46 per hour with the 10% savings) and less the estimated evaporator operating cost ($50.98 per hour) is about $391.02 per hour. EXAMPLE 2 [0030] Reference is made to FIGS. 3 and 4 , which illustrate a prophetic comparison between one processing method and the inventive method. The set-up is essentially the same as shown in FIGS. 1 and 2 , but a more effective centrifugal decanter is used than the one used in Example 1. As a result, the syrup introduced to the disk stack centrifuge 14 would have a moisture content estimated at 60% by weight. While this does not impact the product value figures, the syrup from the centrifuge 14 has a moisture content of only 66.6% by weight, as compared to 82.5% by weight in Example 1. As a result, the cost per hour of drying this syrup when combined with the distillers wet grains to achieve an end product having a moisture content of less than 10% is only $158.92, or approximately 40% less. Assuming a savings in dryer efficiency of 10%, the product value per hour ($678.46) less the estimated dryer operating cost ($143.03 per hour) and less the estimated evaporator operating cost ($74.96 per hour) is $460.46 per hour. This represents an approximate 15% increase over the corresponding value calculated for Example 1. [0031] As should be appreciated, the above-described method and subsystem of the preferred embodiment essentially require the addition of a centrifuge downstream of the evaporator in the conventional system for processing thin stillage (which centrifuge may thus be considered a “means for” recovering oil from thin stillage). Accordingly, instructions on how to implement the above-described method (including the optimum process variables) may be provided along with a centrifuge for use in an ethanol plant for forming the novel subsystem 10 disclosed herein. Such instructions result in the most efficient implementation of the method, as compared to the situation where the scientists or engineers at the plant must experiment with the centrifuge to determine the optimum process conditions required to achieve a favorable result. [0032] The foregoing description provides illustration of the inventive concepts. The descriptions are not intended to be exhaustive or to limit the disclosed invention to the precise form disclosed. Modifications or variations are also possible in light of the above teachings. For example, the syrup recovered from the centrifuge may be evaporated and processed again in a further effort to recover oil before drying. Moreover, in addition to a self-cleaning bowl type of disk stack centrifuge, a nozzle bowl disk stack centrifuge would work as a means for recovering oil from the concentrate, as would a horizontal centrifugal decanter (which may be especially beneficial when the moisture content of the concentrate is less than 50% by weight) or other like devices for separating oil from a substance including suspended solids. Moreover, besides corn, the present invention may have utility with any other grain used in a dry milling process for producing ethanol, such as for example, milo. The embodiments described above were chosen to provide the best application to thereby enable one of ordinary skill in the art to utilize the inventions in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention.
In one aspect of the invention, a method recovers oil from a concentrated byproduct, such as evaporated thin stillage formed during a dry milling process used for producing ethanol. The method includes forming a concentrate from the byproduct and recovering oil from the concentrate. The step of forming the concentrate may comprise evaporating the byproduct. Further, the step of separating the oil from the concentrate may comprise using a centrifuge and, in particular, a disk stack centrifuge. Other aspects of the invention include related methods and subsystems for recovering oil from thin stillage.
Identify and summarize the most critical technical features from the given patent document.
[ "[0001] This divisional application claims the benefit of U.S. Continuation application Ser.", "No. 11/241,231, filed Sep. 30, 2005 which claims priority to U.S. Non-Provisional application Ser.", "No. 11/122,859;", "filed May 5, 2005;", "U.S. Provisional Patent Application Serial No. 60/602,050;", "filed Aug. 17, 2004, the disclosure of which is incorporated herein by reference.", "COPYRIGHT STATEMENT [0002] A portion of the disclosure of this document contains material subject to copyright protection.", "No objection is made to the facsimile reproduction of the patent document or this disclosure as it appears in the Patent and Trademark Office files or records, but any and all rights in the copyright(s) are otherwise reserved.", "TECHNICAL FIELD [0003] The present invention relates generally to recovering oil and, more particularly, to recovering oil from a byproduct of the dry milling process used to form ethanol.", "BACKGROUND OF THE INVENTION [0004] Over the past thirty years, significant attention has been given to the production of ethyl alcohol, or “ethanol,” for use as an alternative fuel.", "Ethanol not only bums cleaner than fossil fuels, but also can be produced using grains such as corn, which are of course renewable resources.", "At present, approximately sixty-nine “dry milling”", "plants in the United States produce over two billion gallons of ethanol per year.", "Additional plants presently under construction are expected to add over four hundred million gallons to this total in an effort to meet the current high demand.", "[0005] As noted in the foregoing discussion, a popular method of producing ethanol is known as “dry milling,” and in the United States is typically practiced using corn.", "As is well known in the industry, the dry milling process utilizes the starch in the corn or other grain to produce the ethanol through fermentation, and creates a waste stream comprised of byproducts termed “whole stillage”", "(which may be further separated into products known as distillers wet grains and “thin stillage”).", "Despite containing valuable oil, this whole stillage has for the most part been treated as waste and used primarily to supplement animal feed (mostly in the form of distillers dried grains with solubles (DDGS), which is created by evaporating the thin stillage, recombining the resulting concentrate or syrup with the distillers wet grains, and drying the product to have a low moisture content;", "see, e.g., U.S. Pat. Nos. 5,662,810 and 5,958,233, the disclosures of which are incorporated herein by reference).", "[0006] Efforts to recover the valuable oil from this byproduct have not been successful in terms of efficiency or economy.", "For example, one approach involves attempting to separate the oil from the thin stillage before the evaporation stage, such as using a centrifuge.", "However, spinning the thin stillage at this stage does not produce usable oil, but rather merely creates an undesirable emulsion phase requiring further processing.", "Moreover, the volume of thin stillage present is generally 2 to 10 times greater than the syrup, which requires considerable capital to purchase the number of centrifuges required.", "Together, these obstacles make attempts to recover oil from thin stillage highly inefficient and uneconomical.", "[0007] U.S. Pat. No. 5,250,182 (the disclosure of which is incorporated herein by reference) describes the use of filters for removing substantially all solids and recovering lactic acid and glycerol from the thin stillage without the need for evaporation.", "Despite eliminating a step in the conventional process, the proposal results in a more complicated arrangement requiring multiple filtration steps.", "Wholesale elimination of the evaporator in the vast majority of existing plants is also unlikely and otherwise uneconomical.", "Filters, and especially the microfiltration and ultrafiltration types proposed in this patent, are also susceptible to frequent plugging and thus disadvantageously increase the operating cost.", "For these reasons, the filtration process proposed in this patent has not gained widespread commercial acceptance.", "[0008] Accordingly, a need exists for a more efficient and economical manner of recovering oil from a byproduct containing it, such as thin stillage created during the dry milling process used to produce ethanol.", "SUMMARY OF THE INVENTION [0009] In accordance with one aspect of the invention, a method of processing a concentrated byproduct of a dry milling process for producing ethanol, such as by using corn, is disclosed.", "In its most basic form, the method comprises recovering oil from the concentrated byproduct.", "[0010] In one embodiment, the byproduct comprises thin stillage, and the method includes the step of evaporating the thin stillage to form a concentrate.", "The recovering step may further comprise separating the oil from the concentrate using a disk stack centrifuge.", "Preferably, the recovering step comprises: (1) providing the concentrated byproduct at a temperature of between about 150 and 212° F. and, most preferably, at a temperature of about 180° F.;", "and/or (2) providing the concentrated byproduct having a pH of between about 3 and 6 and, most preferably, between about 3.5 and 4.5.", "Additionally, it is preferred that the concentrated byproduct have a moisture content greater than 15% by weight, more preferably a moisture content greater than 50% and less than 90% and, most preferably, a moisture content between about 60-85%.", "The step of recovering the oil from the concentrated byproduct produces syrup, and the method may further include the step of recovering oil from the syrup.", "[0011] In accordance with another aspect of the invention, a more specific method of processing concentrated thin stillage created by a dry milling process for producing ethanol, such as from corn, is disclosed.", "The method comprises recovering oil from the concentrated thin stillage having a moisture content of less than about 90% by weight.", "[0012] In one embodiment, the recovering step comprises separating the oil from the concentrate using a disk stack centrifuge.", "The method may further include the step of drying the concentrate after the removing step.", "[0013] In accordance with still another aspect of the invention, a method of recovering oil from thin stillage is disclosed.", "The method comprises evaporating the thin stillage to create a concentrate having a moisture content of greater than 15% by weight and less than about 90% by weight.", "Oil is then recovered by centrifuging the concentrate, preferably using a disk stack centrifuge.", "[0014] In accordance with yet another aspect of the invention, a method of processing whole stillage is disclosed.", "The method comprises recovering thin stillage including oil and solids from the whole stillage, concentrating the thin stillage including the solids, and recovering oil from the concentrate.", "[0015] In one embodiment, the step of recovering the thin stillage includes using a separator selected from the group consisting of a press, extruder, a decanter centrifuge, and a screen centrifuge.", "The concentrating step may comprise processing the thin stillage to a temperature of between about 150 and 212° F., a pH of between about 3 and 6, and a moisture content of less than 90%.", "The step of recovering oil comprises separating the oil from the concentrate using a centrifuge.", "The recovering and concentrating steps may be performed in a continuous fashion.", "The method may further include drying the concentrate after recovering oil.", "[0016] In accordance with a further aspect of the invention, a subsystem for use in a system for producing ethanol by dry milling and creating thin stillage as a byproduct is disclosed.", "The subsystem comprises an evaporator for evaporating the thin stillage to form a concentrate, and a centrifuge for receiving the concentrate and recovering oil therefrom.", "Preferably, the concentrate has a moisture content of less than about 90% by weight, and the centrifuge is a disk stack type.", "[0017] Still a further aspect of the invention is a subsystem for use in a system for producing ethanol by dry milling and creating thin stillage as a byproduct.", "The subsystem comprises an evaporator for evaporating the thin stillage to form a concentrate and means for recovering oil from the concentrate.", "In one embodiment, the recovering means comprises a centrifuge and, most preferably, a disk stack centrifuge.", "[0018] Yet a further aspect of the invention is the combination of a concentrate formed from thin stillage including oil and a centrifuge for removing at least a portion of the oil from the concentrate.", "Preferably, the concentrate has a moisture content of greater than 15% by weight and less than about 90% by weight, and the centrifuge is a self-cleaning bowl type of disk stack centrifuge, a nozzle bowl disk stack centrifuge, or a horizontal centrifugal decanter BRIEF DESCRIPTION OF THE DRAWINGS [0019] FIG. 1 is a partially schematic flow chart illustrating the processing of co-products formed during the ethanol extraction process;", "[0020] FIG. 2 is a partially schematic flow chart illustrating the recovery of oil from a syrup formed by evaporating the thin stillage;", "[0021] FIG. 3 is a schematic view similar to FIG. 1 ;", "and [0022] FIG. 4 is a schematic view similar to FIG. 2 .", "DETAILED DESCRIPTION OF THE INVENTION [0023] In accordance with one aspect of the invention, a method recovers oil from a byproduct resulting from the production of ethanol using a dry milling technique (which is extensively described in the above-referenced '182 patent).", "The byproduct, known as “thin stillage,” is recovered by separating the distillers wet grain from the “whole stillage”", "leftover after fermentation is complete.", "As is known in the art, this mechanical separation may be accomplished using a press/extruder, a decanter centrifuge, or a screen centrifuge.", "Moisture is then removed from the unfiltered thin stillage to create a concentrate or syrup, such as through evaporation.", "Advantageously, usable oil is then easily recovered from this concentrated form of the byproduct through relatively simple mechanical processing, without the prior need for multiple stages of filtration or other expensive and complicated undertakings.", "[0024] In one embodiment, oil is recovered from the concentrate by passing it through a centrifuge and, in particular, a disk stack centrifuge (and most preferably a self-cleaning bowl type).", "Preferably, the concentrate fed to the disk stack centrifuge is at a temperature of between about 150 and 212° F. (and ideally 180° F.) and a pH of between about 3 and 6 (ideally between about 3.5 and 4.5).", "As a result of the preceding evaporation step, the concentrate has a moisture content of greater than 15% and less than about 90%, more preferably between 30% and about 90%, and ideally about 60-85% by weight.", "Under these process conditions, the disk stack centrifuge is able to separate the oil in usable form from the concentrate in an efficient and effective manner, despite the relatively high level of solids present (which may be recovered from the centrifuge in a continuous or intermittent fashion, depending on the particular process conditions).", "[0025] Besides creating usable oil, the concentrate or syrup recovered from the disk stack centrifuge is considered more valuable.", "This is because the post-evaporation processing to recover or remove the oil improves the efficiency of the drying process used on the combined concentrate syrup and distillers wet grains.", "A stable, flowable product for supplementing animal feed results, which thus further complements the value of the oil recovered.", "[0026] Two examples are presented below to demonstrate the efficacy of the above-described method.", "EXAMPLE 1 [0027] Reference is made to FIGS. 1 and 2 to illustrate schematically a first example demonstrating the efficacy of the present method.", "FIG. 1 represents one technique for processing whole stillage resulting from dry milling corn to create distillers dried grains with solubles.", "The whole stillage leftover after deriving the ethanol is mechanically separated into distillers wet grains (approx.", "35% solids) and thin stillage (approx.", "6.7% solids), such as by using a centrifugal decanter.", "The thin stillage is then introduced to an evaporator to create a syrup having a moisture content of approximately 80% by weight and about 17% solids by weight.", "The syrup is then recombined with the distillers wet grains, introduced to a drum dryer, and dried to reduce the overall moisture content to approximately 10% by weight.", "An estimated total value of the resulting distillers dried grains with solubles is $600.36 per hour.", "[0028] FIG. 2 represents the inventive method and a related subsystem 10 for implementing it.", "Initial processing of the whole stillage is done in the same fashion, and the mechanically separated thin stillage is delivered to the evaporator 12 forming part of the subsystem 10 .", "The resulting concentrate or syrup having a moisture content of approximately 80% by weight and a solids content of approximately 17% by weight is delivered to a disk stack centrifuge 14 , and preferably a “solids ejecting”", "one, such as an Alfa Laval Model No. AFPX510, AFPX513, or AFPX617 or equivalent device.", "At an infeed rate of approximately 35 gallons per minute, this centrifuge 14 recovers usable oil at a rate of 538 pounds per hour and produces syrup having a having a moisture content of 82.5% by weight, but with far less oil in view of the preceding recovery step.", "[0029] Recombining the syrup (which is substantially free of oil) from the centrifuge 14 with the distillers wet grains and drying in a drum dryer 16 to a moisture content of 10% by weight results in a product having a value of $576.46 per hour.", "However, the 538 pounds per hour of oil recovered has a product value of approximately $102 per hour.", "Accordingly, the total product value using the inventive method is $678.46 per hour, which is approximately 12% greater than the $600.36 per hour product value resulting from use of the conventional set-up shown in FIG. 1 .", "Moreover, removal of the majority of the oil before the drying step makes the process more efficient, and results in an estimated energy savings of approximately 10%, or $26.27 per hour.", "As a result, product value per hour ($678.46) less the estimated dryer operating cost ($236.46 per hour with the 10% savings) and less the estimated evaporator operating cost ($50.98 per hour) is about $391.02 per hour.", "EXAMPLE 2 [0030] Reference is made to FIGS. 3 and 4 , which illustrate a prophetic comparison between one processing method and the inventive method.", "The set-up is essentially the same as shown in FIGS. 1 and 2 , but a more effective centrifugal decanter is used than the one used in Example 1.", "As a result, the syrup introduced to the disk stack centrifuge 14 would have a moisture content estimated at 60% by weight.", "While this does not impact the product value figures, the syrup from the centrifuge 14 has a moisture content of only 66.6% by weight, as compared to 82.5% by weight in Example 1.", "As a result, the cost per hour of drying this syrup when combined with the distillers wet grains to achieve an end product having a moisture content of less than 10% is only $158.92, or approximately 40% less.", "Assuming a savings in dryer efficiency of 10%, the product value per hour ($678.46) less the estimated dryer operating cost ($143.03 per hour) and less the estimated evaporator operating cost ($74.96 per hour) is $460.46 per hour.", "This represents an approximate 15% increase over the corresponding value calculated for Example 1.", "[0031] As should be appreciated, the above-described method and subsystem of the preferred embodiment essentially require the addition of a centrifuge downstream of the evaporator in the conventional system for processing thin stillage (which centrifuge may thus be considered a “means for”", "recovering oil from thin stillage).", "Accordingly, instructions on how to implement the above-described method (including the optimum process variables) may be provided along with a centrifuge for use in an ethanol plant for forming the novel subsystem 10 disclosed herein.", "Such instructions result in the most efficient implementation of the method, as compared to the situation where the scientists or engineers at the plant must experiment with the centrifuge to determine the optimum process conditions required to achieve a favorable result.", "[0032] The foregoing description provides illustration of the inventive concepts.", "The descriptions are not intended to be exhaustive or to limit the disclosed invention to the precise form disclosed.", "Modifications or variations are also possible in light of the above teachings.", "For example, the syrup recovered from the centrifuge may be evaporated and processed again in a further effort to recover oil before drying.", "Moreover, in addition to a self-cleaning bowl type of disk stack centrifuge, a nozzle bowl disk stack centrifuge would work as a means for recovering oil from the concentrate, as would a horizontal centrifugal decanter (which may be especially beneficial when the moisture content of the concentrate is less than 50% by weight) or other like devices for separating oil from a substance including suspended solids.", "Moreover, besides corn, the present invention may have utility with any other grain used in a dry milling process for producing ethanol, such as for example, milo.", "The embodiments described above were chosen to provide the best application to thereby enable one of ordinary skill in the art to utilize the inventions in various embodiments and with various modifications as are suited to the particular use contemplated.", "All such modifications and variations are within the scope of the invention." ]
FIELD OF THE INVENTION This invention relates generally to the field of counterfeit-deterring images and more and specifically to a method and apparatus for producing multiple counterfeit-deterring images separately decodable by a multi-section lens. BACKGROUND OF THE INVENTION To prevent unauthorized duplicates or alteration of documents, indicia or a background pattern can be provided. For instance, documents including tickets, checks, passports, banknotes, currency, product labels and the like may be easily counterfeited if counterfeit-deterring images are not employed. The indicia imposed upon a document is typically performed by a printing process such as offset printing, lithography, letterpress or other like mechanical systems or through a variety of photographic methods, by xeroprinting, and a host of other methods. The patterns or indicia may be reproduced with ordinary inks, from special inks which may be magnetic, fluorescent, or the like, from powders which may be baked on, from light sensitive materials such as silver salts or azo dyes, and the like. Most of these patterns placed on sheet materials depend upon complexity and resolution to avoid ready duplication. Consequently, they add an increment of cost to the sheet material without being fully effective in many instances in providing the desired protection from unauthorized duplication or alteration. Various methods of counterfeit-deterrent strategies have been suggested including Moire-inducing line structures, variable-sized dot patterns, latent images, see-through bars, bar codes, and diffraction based holograms. However, none of these methods employs a true encoded image or the added security benefits derived therefrom. The instant inventor has been awarded a number of patents on various encoding processes including U.S. Pat. Nos. 3,937,565; 3,524,395; 4,092,654; 4,198,147; 4,914,700; and 5,708,717 the contents of which are herein incorporated by reference. U.S. Pat. No. 5,708,717 discloses a system and method for a Digital Anti-counterfeiting Software Method and Apparatus wherein a latent image was placed onto a source image implemented by a computer software program, such that the latent image is only visible when viewed through a special decoder lens. These principles and embodiments are hereby incorporated by reference. The greater the frequency the greater the complexity of the encoding and thus the greater the difficulty in counterfeiting a product that has been encoded utilizing the inventor's technology. However, it has been found that the use of images encoded by multiple frequencies making them readable by different lens or a combination thereof has produced a new and unique level of encoding. Accordingly, what is needed in the art is a method and apparatus for producing multiple counterfeit-deterring images that can be decoded individually or together by a lens having multiple active decoding sections or layers, or by use of a combination of lenses. The multiple images provide an increasingly complex encoding of latent images for enhancing security. The instant invention includes a lens having at least two active decoding sections wherein, each section may have a unique frequency based upon the curvature of that lens. For the purposes of this invention, a lens is defined as any device capable of altering the character of transmitted or reflected light, in accordance with specifically defined parameters, e.g. lenticular parameters. The anti-counterfeiting software will be used to match the lens parameters thereby providing an encoding of a latent image or images(s) at least once, each encoding being a function of the parameters of a section of the decoding lens having specific frequency and/or lens curvature parameters. The angle of the curvature further permits a lower frequency, but when coupled to the double encoding, results in an increased complexity to the encoded latent image. Further, by modifying the curvature, the thickness of the lens corresponding to a particular frequency can be modified providing a paper thin lens. Thus, in one embodiment the latent images can only be viewed through a multi-section lens decoder having a section with parameters that corresponds to each encoding. In another embodiment different latent images found within the same image, can be decoded by use of multiple lenses allowing different levels of security. As a result, the inventor has significantly enhanced the anti-counterfeiting aspect of his invention. SUMMARY OF THE INVENTION The present invention provides a software method and apparatus for digitally encoding and incorporating latent images having differing frequency readings into a source image, and a lens having at least two sections adapted to recognize distinct parameters, e.g. frequencies, for decoding of the latent images. The latent images, as implemented by a computer software program, are placed into a rasterized source image such that the latent images are then readable only when viewed through the multi-section lens decoder with particularly modified parameters. Thus, each encoding is a function of the particular parameters, for example lenticular parameters such as the frequency and curvature of a particular lens section. One or more latent images, in digitalized form, can be encoded at least once for decoding by a variety of lenticular lenses as selected by the user, with each lens having different optical properties such as different line densities per inch and/or different radius of curvature for the lenticular. The properties of the encoded latent images are dependent upon the parameters of the decoding lens. Thus, one latent image twice encoded may include a first encoding dependent upon the frequency and curvature radius of a first lens section and a second encoded image may be based upon the corresponding parameters of a second lens section. In another embodiment, two or more latent images may be encoded into a source image with each latent image being related to a lenticular parameters of two or more separate lenses or sections thereof. The curvature of the lenticular is modified such that the frequency or lines per inch can be lowered but comparable to high densities without the modified curvature. The inventor has further intensified the complexity of the latent image by having two or more encodings of the same or different images. This requires a multi-section lens, one section per encoding. In one embodiment, the resulting lens may be a relatively thick lens capable of decoding complex latent images, or a lens containing a plurality of sections, each having particular and distinct lenticular parameters. Different degrees of encoding might also be selected wherein the latent image is divided up into a higher multiplicity of lines or elements. Again, for decoding purposes, the multiplicity of elements would be a function of the lens density and/or curvature. When a latent image(s) is encoded for use with the instant lens, a source image is rasterized, or divided up into a series of lines equal in number to the lines making up the encoded latent images. Generally, when hard copy images are printed, the image is made up of a series of “printers dots” which vary in density according to the colors found in the various component parts of the image. A proprietary software program takes the rasterized lines of the source image and reforms them into the same general pattern as the lines of the encoded latent images. As a result, where the source image is darker, the encoded lines are formed proportionately thicker and similarly where the source image is lighter, the encoded lines are formed proportionately thinner. The subsequent combined image appears to the naked eye to be simply the original source image. However, since the component rasterized lines are formed in the coded pattern of the encoded latent image(s), a double lens decoder will reveal the underlying latent image(s). Due to the high resolution needed for the complex encoded lines, attempts to decode the printed image by other lens or otherwise are generally unsuccessful in reproducing the underlying multi-encoded latent image(s). As a result of multi-section lenses, several latent images, each corresponding to the parameters of a section of the lens, can be encoded and then reformed into the rasterized source image. Alternatively, the same latent image can be encoded two or more times to correspond to the parameters of the various sections of the lens and then reformed into the rasterized source image. This is achieved by dividing the rasterized lines into the appropriate number of images (or phases) and interlacing the phased images in each raster line element. Each individual latent image might be oriented at any angle and encoded to a different degree, so long as the encoding of each image is a functional multiple of the known decoder frequency and curvature. Alternatively, the grey scale source image might be divided up into primary component printing colors (e.g. cyan, magenta, yellow, and black, or CMYK; red, green, blue, or RGB). Single color bitmap formats might also be used for certain applications. An encoded latent image, or a multi-phased image, could then be individually reformed into each component color. Upon rejoining of the colors to form the final source image, the decoder will reveal the different latent images hidden in the different color segments. The decoder includes at least two active decoding areas which may define any combination of frequencies, radius of curvatures, or angles between the frequencies, and may define two or more sections. Useful applications might include the latent encoding of a person's signature inside a source image consisting of that person's photograph. Such a technique would make it virtually impossible to produce fake ID's or driver's licenses through the common technique of replacing an existing picture with a false one. Other vital information besides the person's signature (e.g. height, weight, identification number, etc.) might also be included in the latent image for encoding into the source image. Still other useful applications might include, but are not limited to the following: credit cards, passports, photo-identification cards, currency, special event tickets, stocks and bond certificates, bank and travelers checks, anti-counterfeiting labels (e.g. for designer clothes, drugs, liquors, video tapes, audio CD's, cosmetics, machine parts, and pharmaceuticals), tax and postage stamps, birth certificates, vehicle restoration cards, land deed titles, and visas. In any of the above examples, the same latent image may be encoded two or more times at different frequencies, different curvatures, or different angles or two or more latent images may be encoded at the same frequency and curvature but with different angles or with different frequencies and curvatures and different angles. The criteria is that the encoded images be a function of the parameters of the multi-sectioned decoder such that each section's properties have a corresponding encoded latent image. Accordingly, it is an objective of the instant invention to disclose a multi-layer or multi-sectioned lens for decoding at least two encodings of at least one latent image rasterized into a source image, each layer or section of the lens having the ability to render visible a corresponding encoded image that is a function of the parameters of that section. Another objective of the present invention is to disclose a multi-sectioned lens for decoding a corresponding encoded latent image which is matched to the frequency and curvature of each lens section, as implemented by a software program on a computer system, typically in printed form. Still another object of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the source image is converted into a grey scale image for incorporation of a latent encoded image. A related objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the grey scale source image is further separated out into its color parts for possible incorporation of latent encoded images into each component color part, with the parts being rejoined to form the final encoded source image. A related objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct individual lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the elemental lines of the encoded image may be rotated or flipped about their axis as necessary, or as selected by the user. A further objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the “single phased” encoded image consists of a first latent image which has been sliced and encoded as a function of a user selected decoder density and encoding factor. Yet another objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the “two phased” encoded image is sliced as a function of a user selected decoder density, and each slice is halved into two sub-slices, and the first and second latent images are alternately interlaced in the sub-slices, with each latent image encoded by a user selected encoding factor. Still another objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the “three phased” encoded image is sliced as a function of a user selected decoder density, and each slice is divided into three sub-slices, and the first, second, and third latent images are alternately interlaced in the sub-slices, with each latent image encoded by a user selected encoding factor. Yet another objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein an “indicia tint” is produced which is similar to a two phased encoded image, but with one source file, and every second sub-slice of the input image is the complement of the first sub-slice. A further objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the source image consists of a solid color or tint pattern with the encoded image incorporated therein, but the elemental lines are flipped only where a letter or object occurs in underlying latent image. Still another objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based-upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the latent image is encoded directly into a certain visible figure on the source image, thus creating a “hidden image” effect. Yet another objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein a bitmap source image is used (instead of a grey scale image) to create hidden images behind single color source images or sections of source images. Still another related objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein a multilevel, 3-dimensional relief effect is decoded by decoding different encoding parameters corresponding to the parameters of each section. Still another possible objective of the present invention is to disclose a decoder lens having holographic images produced through line diffraction techniques for indicating authenticity of the lens. Other objectives and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a cross section of a horizontal view of the multi-section decoding lens and FIG. 2 shows the corrected lenticular of a first and second section of the multi-section decoding lens. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Although the invention will be described in terms a specific embodiment with certain alternatives, it will be readily apparent to those skilled in this art that various modifications, rearrangements and substitutions can be made without departing from the spirit of the invention. The scope of the invention is defined by the claims appended hereto. How an object is viewed under a lens depends on the lens' focal length and radius of curvature. As light passes through a lens it undergoes two refractions. Refraction or bending of light occurs as light passes from one medium to another when there is a difference in the index of refraction between the two materials. At the first surface, as the light enters the lens, it passes from air into the plastic or glass. Then the light travels through the lens. At the other side of the lens, the light again refracts as it goes from the lens to air. The surface of the lens may be curved in such a manner as to direct the light in a certain direction. Within the lens itself there may be modifications in the curvature to further refract the light. Now referring to FIG. 1 , shown is cross section of a horizontal view of the multi-section decoding lens. A ray of light ( 10 ) enters a curvature ( 12 ) of a second lens ( 14 ). The curvature ( 12 ) has been modified to refract the light ( 10 ) to a predetermined angle. Thus, the light is redirected in a specific manner to decode a correlated second latent encoded image ( 22 ) embedded in a rasterized source image in an object ( 24 ). The light ( 10 ) then passes to a first lens ( 16 ) with a different radius of curvature ( 18 ) that refracts the light ( 10 ) a second time. The light ( 10 ) passing through the first lens ( 14 ) decodes a correlated first latent encoded image ( 20 ) imbedded in a rasterized source image in a document( 24 ). The inventor has discovered that by modifying the radius of curvature, a lower frequency may be employed. The modified curvature coupled with such double encoding generates an increased complexity to the encoded latent image. Further, by modifying the curvature, the thickness of the lens corresponding to a particular frequency can be increased by three. As a result, a lower frequency can be employed but the decoding lens remains dense and thus of practical use for decoding increasingly complex encoded latent images. Further, by utilizing multi-sectioned lenses and thus multi-encoding, the complexity of the encoded latent images is significantly enhanced making counterfeiting of an object and reproduction of the multi-section decoding lens increasingly untenable. Now referring to FIG. 2 , shown is a corrected lenticular of a first and second section of a multi-section decoding lens. The first section ( 10 ), the bottom section, shows a 300 line corrected lenticular 10 degree angle lens with a direction of 105 degrees. The modifiable parameters of a section are its frequency and curvature. Thus, the frequency of the lens is 300 lines per inch and the curvature is 10 degrees causing the light to be directed 105 degrees. The second section ( 12 ), the top section, shows a 250.1 line lenticular 30 degree angle lens with a direction of 15 degrees. The inventor's software program will scramble a latent image and then embed that latent image into a rasterized source image. The program will correlate the first encoding of the latent image to correspond to the parameters of the first lens and the second latent image to correspond to the parameters of the second lens. Thus, the encoding of the latent image is a function of the frequency and curvature of a particular lens. The software can be programed to scramble the same latent image at least twice or to scramble different images. The double encoding permits an elevated level of security not previously available making counterfeiting of objects incorporating this invention much more arduous. Further, reproduction of the multi-section lens decoder would require knowledge of the radius of curvature and frequency for all sections, a formidable task which renders such reproduction problematic. An expected application of the present invention is where multi-levels of security are needed. For example, a company will issue a standard decoder lens to all employees. The first section of the multi-section lens will allow an employee access to all minimum security areas. Employees with authority to enter maximum security areas would have a second section with parameters different than those of the first section allowing a second latent image to be decoded whereas those without authority would have a second section with the same parameters as the first section and the second image could not be decoded. Thus, to gain entrance to maximum security, the authorized employee must have a decoder capable of unencoding both latent images. The decoder may contain the employees signature or picture to prevent unauthorized use. Additionally, a hologram may be imprinted in the decoding lens for visual verification of the authenticity of the decoder itself. The Encoded Indicia process involves rasterizing, or dividing up into lines, a source or visible image according to the frequency (or density) of a lenticular decoder lens. The number of lines is also a function of the encoding factor, or zoom factor, as applied to a latent or secondary image. After the latent image is processed and encoded, a set of encoded lines exists which can then be combined into the rasterized lines of the visible image. The visible image is thus reformed, or re-rasterized, according to the pattern of the encoded latent image lines. Where the visible image is darker, the encoded lines are made proportionately thicker in re-forming the rasterized lines of the visible image; similarly, where the visible image is lighter, the encoded lines are made proportionately thinner. As a result, a new visible image is created, but with the encoded, latent, pattern being visible “underneath” when viewed through a transparent decoder lens. As for lens density, the inventor has assigned reference names to lenses with various frequencies (or line densities per inch), including for instance, the following: D-7X with 177 lines/inch; D-7 with 152.5 lines/inch; D-6 with 134 lines/inch; D-9 with 69 lines/inch. (See reference 6). The software for performing this process also provides an “×2” (or doubling factor, df) option which doubles the effective line density, and hence divides the output image up into twice as many slices. The resulting image will still be decodable by the selected lens because the number of lines is an even multiple of the frequency of the lens. The output image slice, having width h, is processed as a function of the input slice width i (see reference 8). In turn, width i is a function of width h, the lens density, and a base code factor (or encoding factor) as selected by the user. These formulas are as follows: df=2 (if “×2” selected); 1 (by default) o=h*density/100 (See reference 10) i=o*base code(B) (See reference 8) Rearranging these formulas, the value for h becomes: h = ( 1 / B ) * 100 Density * df Hence, as the value for the base code and/or the density is increased, the width h will decrease. A larger base code, or encoding factor, therefore creates more lines and results in a more distorted or encoded image. This effect will allow the latent image to be visible only when viewed through a decoder. Additionally, the latent image might consist of a one, two, or three multi-phased images as created using previous interface screens for multi-phased images and saved in an appropriate file. inventor refers to this technique as Encoded Micro Lines. All patents and publications mentioned in this specification are indicative of the levels of those skilled in the art to which the invention pertains. All patents and publications are herein incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference. One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims.
The present invention is a multi-section lens for decoding at least two encodings, as a function of the parameters of a lens section, of at least one latent image, as implemented by a software program on a computer system, for security measures such as determining the authenticity of an object. The encoded latent image is a function of distinct lenticular parameters which may include the frequency and lens radius of curvature of a particular lens section. Each section has a corresponding encoded latent image thus allowing for multiple latent images and multiple encodings making it virtually impossible to counterfeit the encoded object or the decoding apparatus.
Identify the most important claim in the given context and summarize it
[ "FIELD OF THE INVENTION This invention relates generally to the field of counterfeit-deterring images and more and specifically to a method and apparatus for producing multiple counterfeit-deterring images separately decodable by a multi-section lens.", "BACKGROUND OF THE INVENTION To prevent unauthorized duplicates or alteration of documents, indicia or a background pattern can be provided.", "For instance, documents including tickets, checks, passports, banknotes, currency, product labels and the like may be easily counterfeited if counterfeit-deterring images are not employed.", "The indicia imposed upon a document is typically performed by a printing process such as offset printing, lithography, letterpress or other like mechanical systems or through a variety of photographic methods, by xeroprinting, and a host of other methods.", "The patterns or indicia may be reproduced with ordinary inks, from special inks which may be magnetic, fluorescent, or the like, from powders which may be baked on, from light sensitive materials such as silver salts or azo dyes, and the like.", "Most of these patterns placed on sheet materials depend upon complexity and resolution to avoid ready duplication.", "Consequently, they add an increment of cost to the sheet material without being fully effective in many instances in providing the desired protection from unauthorized duplication or alteration.", "Various methods of counterfeit-deterrent strategies have been suggested including Moire-inducing line structures, variable-sized dot patterns, latent images, see-through bars, bar codes, and diffraction based holograms.", "However, none of these methods employs a true encoded image or the added security benefits derived therefrom.", "The instant inventor has been awarded a number of patents on various encoding processes including U.S. Pat. Nos. 3,937,565;", "3,524,395;", "4,092,654;", "4,198,147;", "4,914,700;", "and 5,708,717 the contents of which are herein incorporated by reference.", "U.S. Pat. No. 5,708,717 discloses a system and method for a Digital Anti-counterfeiting Software Method and Apparatus wherein a latent image was placed onto a source image implemented by a computer software program, such that the latent image is only visible when viewed through a special decoder lens.", "These principles and embodiments are hereby incorporated by reference.", "The greater the frequency the greater the complexity of the encoding and thus the greater the difficulty in counterfeiting a product that has been encoded utilizing the inventor's technology.", "However, it has been found that the use of images encoded by multiple frequencies making them readable by different lens or a combination thereof has produced a new and unique level of encoding.", "Accordingly, what is needed in the art is a method and apparatus for producing multiple counterfeit-deterring images that can be decoded individually or together by a lens having multiple active decoding sections or layers, or by use of a combination of lenses.", "The multiple images provide an increasingly complex encoding of latent images for enhancing security.", "The instant invention includes a lens having at least two active decoding sections wherein, each section may have a unique frequency based upon the curvature of that lens.", "For the purposes of this invention, a lens is defined as any device capable of altering the character of transmitted or reflected light, in accordance with specifically defined parameters, e.g. lenticular parameters.", "The anti-counterfeiting software will be used to match the lens parameters thereby providing an encoding of a latent image or images(s) at least once, each encoding being a function of the parameters of a section of the decoding lens having specific frequency and/or lens curvature parameters.", "The angle of the curvature further permits a lower frequency, but when coupled to the double encoding, results in an increased complexity to the encoded latent image.", "Further, by modifying the curvature, the thickness of the lens corresponding to a particular frequency can be modified providing a paper thin lens.", "Thus, in one embodiment the latent images can only be viewed through a multi-section lens decoder having a section with parameters that corresponds to each encoding.", "In another embodiment different latent images found within the same image, can be decoded by use of multiple lenses allowing different levels of security.", "As a result, the inventor has significantly enhanced the anti-counterfeiting aspect of his invention.", "SUMMARY OF THE INVENTION The present invention provides a software method and apparatus for digitally encoding and incorporating latent images having differing frequency readings into a source image, and a lens having at least two sections adapted to recognize distinct parameters, e.g. frequencies, for decoding of the latent images.", "The latent images, as implemented by a computer software program, are placed into a rasterized source image such that the latent images are then readable only when viewed through the multi-section lens decoder with particularly modified parameters.", "Thus, each encoding is a function of the particular parameters, for example lenticular parameters such as the frequency and curvature of a particular lens section.", "One or more latent images, in digitalized form, can be encoded at least once for decoding by a variety of lenticular lenses as selected by the user, with each lens having different optical properties such as different line densities per inch and/or different radius of curvature for the lenticular.", "The properties of the encoded latent images are dependent upon the parameters of the decoding lens.", "Thus, one latent image twice encoded may include a first encoding dependent upon the frequency and curvature radius of a first lens section and a second encoded image may be based upon the corresponding parameters of a second lens section.", "In another embodiment, two or more latent images may be encoded into a source image with each latent image being related to a lenticular parameters of two or more separate lenses or sections thereof.", "The curvature of the lenticular is modified such that the frequency or lines per inch can be lowered but comparable to high densities without the modified curvature.", "The inventor has further intensified the complexity of the latent image by having two or more encodings of the same or different images.", "This requires a multi-section lens, one section per encoding.", "In one embodiment, the resulting lens may be a relatively thick lens capable of decoding complex latent images, or a lens containing a plurality of sections, each having particular and distinct lenticular parameters.", "Different degrees of encoding might also be selected wherein the latent image is divided up into a higher multiplicity of lines or elements.", "Again, for decoding purposes, the multiplicity of elements would be a function of the lens density and/or curvature.", "When a latent image(s) is encoded for use with the instant lens, a source image is rasterized, or divided up into a series of lines equal in number to the lines making up the encoded latent images.", "Generally, when hard copy images are printed, the image is made up of a series of “printers dots”", "which vary in density according to the colors found in the various component parts of the image.", "A proprietary software program takes the rasterized lines of the source image and reforms them into the same general pattern as the lines of the encoded latent images.", "As a result, where the source image is darker, the encoded lines are formed proportionately thicker and similarly where the source image is lighter, the encoded lines are formed proportionately thinner.", "The subsequent combined image appears to the naked eye to be simply the original source image.", "However, since the component rasterized lines are formed in the coded pattern of the encoded latent image(s), a double lens decoder will reveal the underlying latent image(s).", "Due to the high resolution needed for the complex encoded lines, attempts to decode the printed image by other lens or otherwise are generally unsuccessful in reproducing the underlying multi-encoded latent image(s).", "As a result of multi-section lenses, several latent images, each corresponding to the parameters of a section of the lens, can be encoded and then reformed into the rasterized source image.", "Alternatively, the same latent image can be encoded two or more times to correspond to the parameters of the various sections of the lens and then reformed into the rasterized source image.", "This is achieved by dividing the rasterized lines into the appropriate number of images (or phases) and interlacing the phased images in each raster line element.", "Each individual latent image might be oriented at any angle and encoded to a different degree, so long as the encoding of each image is a functional multiple of the known decoder frequency and curvature.", "Alternatively, the grey scale source image might be divided up into primary component printing colors (e.g. cyan, magenta, yellow, and black, or CMYK;", "red, green, blue, or RGB).", "Single color bitmap formats might also be used for certain applications.", "An encoded latent image, or a multi-phased image, could then be individually reformed into each component color.", "Upon rejoining of the colors to form the final source image, the decoder will reveal the different latent images hidden in the different color segments.", "The decoder includes at least two active decoding areas which may define any combination of frequencies, radius of curvatures, or angles between the frequencies, and may define two or more sections.", "Useful applications might include the latent encoding of a person's signature inside a source image consisting of that person's photograph.", "Such a technique would make it virtually impossible to produce fake ID's or driver's licenses through the common technique of replacing an existing picture with a false one.", "Other vital information besides the person's signature (e.g. height, weight, identification number, etc.) might also be included in the latent image for encoding into the source image.", "Still other useful applications might include, but are not limited to the following: credit cards, passports, photo-identification cards, currency, special event tickets, stocks and bond certificates, bank and travelers checks, anti-counterfeiting labels (e.g. for designer clothes, drugs, liquors, video tapes, audio CD's, cosmetics, machine parts, and pharmaceuticals), tax and postage stamps, birth certificates, vehicle restoration cards, land deed titles, and visas.", "In any of the above examples, the same latent image may be encoded two or more times at different frequencies, different curvatures, or different angles or two or more latent images may be encoded at the same frequency and curvature but with different angles or with different frequencies and curvatures and different angles.", "The criteria is that the encoded images be a function of the parameters of the multi-sectioned decoder such that each section's properties have a corresponding encoded latent image.", "Accordingly, it is an objective of the instant invention to disclose a multi-layer or multi-sectioned lens for decoding at least two encodings of at least one latent image rasterized into a source image, each layer or section of the lens having the ability to render visible a corresponding encoded image that is a function of the parameters of that section.", "Another objective of the present invention is to disclose a multi-sectioned lens for decoding a corresponding encoded latent image which is matched to the frequency and curvature of each lens section, as implemented by a software program on a computer system, typically in printed form.", "Still another object of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the source image is converted into a grey scale image for incorporation of a latent encoded image.", "A related objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the grey scale source image is further separated out into its color parts for possible incorporation of latent encoded images into each component color part, with the parts being rejoined to form the final encoded source image.", "A related objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct individual lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the elemental lines of the encoded image may be rotated or flipped about their axis as necessary, or as selected by the user.", "A further objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the “single phased”", "encoded image consists of a first latent image which has been sliced and encoded as a function of a user selected decoder density and encoding factor.", "Yet another objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the “two phased”", "encoded image is sliced as a function of a user selected decoder density, and each slice is halved into two sub-slices, and the first and second latent images are alternately interlaced in the sub-slices, with each latent image encoded by a user selected encoding factor.", "Still another objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the “three phased”", "encoded image is sliced as a function of a user selected decoder density, and each slice is divided into three sub-slices, and the first, second, and third latent images are alternately interlaced in the sub-slices, with each latent image encoded by a user selected encoding factor.", "Yet another objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein an “indicia tint”", "is produced which is similar to a two phased encoded image, but with one source file, and every second sub-slice of the input image is the complement of the first sub-slice.", "A further objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the source image consists of a solid color or tint pattern with the encoded image incorporated therein, but the elemental lines are flipped only where a letter or object occurs in underlying latent image.", "Still another objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based-upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein the latent image is encoded directly into a certain visible figure on the source image, thus creating a “hidden image”", "effect.", "Yet another objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein a bitmap source image is used (instead of a grey scale image) to create hidden images behind single color source images or sections of source images.", "Still another related objective of the present invention is to disclose a multi-section lens for decoding at least two encodings based upon the parameters of distinct lens sections of at least one latent image, as implemented by a software program on a computer system, wherein a multilevel, 3-dimensional relief effect is decoded by decoding different encoding parameters corresponding to the parameters of each section.", "Still another possible objective of the present invention is to disclose a decoder lens having holographic images produced through line diffraction techniques for indicating authenticity of the lens.", "Other objectives and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention.", "The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a cross section of a horizontal view of the multi-section decoding lens and FIG. 2 shows the corrected lenticular of a first and second section of the multi-section decoding lens.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Although the invention will be described in terms a specific embodiment with certain alternatives, it will be readily apparent to those skilled in this art that various modifications, rearrangements and substitutions can be made without departing from the spirit of the invention.", "The scope of the invention is defined by the claims appended hereto.", "How an object is viewed under a lens depends on the lens'", "focal length and radius of curvature.", "As light passes through a lens it undergoes two refractions.", "Refraction or bending of light occurs as light passes from one medium to another when there is a difference in the index of refraction between the two materials.", "At the first surface, as the light enters the lens, it passes from air into the plastic or glass.", "Then the light travels through the lens.", "At the other side of the lens, the light again refracts as it goes from the lens to air.", "The surface of the lens may be curved in such a manner as to direct the light in a certain direction.", "Within the lens itself there may be modifications in the curvature to further refract the light.", "Now referring to FIG. 1 , shown is cross section of a horizontal view of the multi-section decoding lens.", "A ray of light ( 10 ) enters a curvature ( 12 ) of a second lens ( 14 ).", "The curvature ( 12 ) has been modified to refract the light ( 10 ) to a predetermined angle.", "Thus, the light is redirected in a specific manner to decode a correlated second latent encoded image ( 22 ) embedded in a rasterized source image in an object ( 24 ).", "The light ( 10 ) then passes to a first lens ( 16 ) with a different radius of curvature ( 18 ) that refracts the light ( 10 ) a second time.", "The light ( 10 ) passing through the first lens ( 14 ) decodes a correlated first latent encoded image ( 20 ) imbedded in a rasterized source image in a document( 24 ).", "The inventor has discovered that by modifying the radius of curvature, a lower frequency may be employed.", "The modified curvature coupled with such double encoding generates an increased complexity to the encoded latent image.", "Further, by modifying the curvature, the thickness of the lens corresponding to a particular frequency can be increased by three.", "As a result, a lower frequency can be employed but the decoding lens remains dense and thus of practical use for decoding increasingly complex encoded latent images.", "Further, by utilizing multi-sectioned lenses and thus multi-encoding, the complexity of the encoded latent images is significantly enhanced making counterfeiting of an object and reproduction of the multi-section decoding lens increasingly untenable.", "Now referring to FIG. 2 , shown is a corrected lenticular of a first and second section of a multi-section decoding lens.", "The first section ( 10 ), the bottom section, shows a 300 line corrected lenticular 10 degree angle lens with a direction of 105 degrees.", "The modifiable parameters of a section are its frequency and curvature.", "Thus, the frequency of the lens is 300 lines per inch and the curvature is 10 degrees causing the light to be directed 105 degrees.", "The second section ( 12 ), the top section, shows a 250.1 line lenticular 30 degree angle lens with a direction of 15 degrees.", "The inventor's software program will scramble a latent image and then embed that latent image into a rasterized source image.", "The program will correlate the first encoding of the latent image to correspond to the parameters of the first lens and the second latent image to correspond to the parameters of the second lens.", "Thus, the encoding of the latent image is a function of the frequency and curvature of a particular lens.", "The software can be programed to scramble the same latent image at least twice or to scramble different images.", "The double encoding permits an elevated level of security not previously available making counterfeiting of objects incorporating this invention much more arduous.", "Further, reproduction of the multi-section lens decoder would require knowledge of the radius of curvature and frequency for all sections, a formidable task which renders such reproduction problematic.", "An expected application of the present invention is where multi-levels of security are needed.", "For example, a company will issue a standard decoder lens to all employees.", "The first section of the multi-section lens will allow an employee access to all minimum security areas.", "Employees with authority to enter maximum security areas would have a second section with parameters different than those of the first section allowing a second latent image to be decoded whereas those without authority would have a second section with the same parameters as the first section and the second image could not be decoded.", "Thus, to gain entrance to maximum security, the authorized employee must have a decoder capable of unencoding both latent images.", "The decoder may contain the employees signature or picture to prevent unauthorized use.", "Additionally, a hologram may be imprinted in the decoding lens for visual verification of the authenticity of the decoder itself.", "The Encoded Indicia process involves rasterizing, or dividing up into lines, a source or visible image according to the frequency (or density) of a lenticular decoder lens.", "The number of lines is also a function of the encoding factor, or zoom factor, as applied to a latent or secondary image.", "After the latent image is processed and encoded, a set of encoded lines exists which can then be combined into the rasterized lines of the visible image.", "The visible image is thus reformed, or re-rasterized, according to the pattern of the encoded latent image lines.", "Where the visible image is darker, the encoded lines are made proportionately thicker in re-forming the rasterized lines of the visible image;", "similarly, where the visible image is lighter, the encoded lines are made proportionately thinner.", "As a result, a new visible image is created, but with the encoded, latent, pattern being visible “underneath”", "when viewed through a transparent decoder lens.", "As for lens density, the inventor has assigned reference names to lenses with various frequencies (or line densities per inch), including for instance, the following: D-7X with 177 lines/inch;", "D-7 with 152.5 lines/inch;", "D-6 with 134 lines/inch;", "D-9 with 69 lines/inch.", "(See reference 6).", "The software for performing this process also provides an “×2”", "(or doubling factor, df) option which doubles the effective line density, and hence divides the output image up into twice as many slices.", "The resulting image will still be decodable by the selected lens because the number of lines is an even multiple of the frequency of the lens.", "The output image slice, having width h, is processed as a function of the input slice width i (see reference 8).", "In turn, width i is a function of width h, the lens density, and a base code factor (or encoding factor) as selected by the user.", "These formulas are as follows: df=2 (if “×2”", "selected);", "1 (by default) o=h*density/100 (See reference 10) i=o*base code(B) (See reference 8) Rearranging these formulas, the value for h becomes: h = ( 1 / B ) * 100 Density * df Hence, as the value for the base code and/or the density is increased, the width h will decrease.", "A larger base code, or encoding factor, therefore creates more lines and results in a more distorted or encoded image.", "This effect will allow the latent image to be visible only when viewed through a decoder.", "Additionally, the latent image might consist of a one, two, or three multi-phased images as created using previous interface screens for multi-phased images and saved in an appropriate file.", "inventor refers to this technique as Encoded Micro Lines.", "All patents and publications mentioned in this specification are indicative of the levels of those skilled in the art to which the invention pertains.", "All patents and publications are herein incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference.", "One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein.", "The methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary and are not intended as limitations on the scope.", "Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims.", "Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments.", "Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims." ]
CROSS-REFERENCE TO RELATED APPLICATIONS This application is a National Stage Application of PCT/IB2012/051983, filed 19 Apr. 2012, which claims benefit of Serial No. 898-2011, filed 20 Apr. 2011 in Chile and which applications are incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the above disclosed applications. BACKGROUND From the discovery of the X-ray in 1895 until now, the emission of a radiation ray, at any energy range, is essentially divergent and the intensity is a function of the distance between it and the emission source (inverse square law). This is due to the X-ray production mechanism; in other words, electrons that impact a target. There are currently several ways to generate X-ray beams, each with a determined source size and a specific, always-positive divergence. The X-ray beams employed in radiotherapy are divergent. The expected objective of radiotherapy is, by using X-rays, to achieve a high X-ray flow zone within a specific volume. These X-rays would then deposit their energy. The energy deposited per unit mass is known as dose in radiotherapy. Since the beam that is used is noticeably divergent, several beams (fields) aimed at the volume of interest must be employed. As is widely known, the depth dose for an X-ray beam is dependent on an exponential downward curve according to the depth, with a maximum value near the surface. A multi-field application allows for a maximum dose in the interest volume (tumor site), despite the fact that the dose values in the surrounding areas are lower than those at the tumor site. These dose values are significant as they have higher values than what is tolerable in some cases, which can prevent the use of an effective dose in the tumor. More refined techniques such as Intensity Modulated Radio Therapy (IMRT) or arc therapy improve and conform the maximum flow volume of X-rays, thus lowering dose levels in neighboring tissues and organs, though this decrease is not significant. A dose value decrease of up to 80% in tissues and organs near the interest zone has currently been achieved in relation to the dose in the interest zone. Treatment planning, however, continues to be complex. A decrease of collateral effects caused by radiation is always attempted, though their complete elimination is impossible. A radiotherapy technique that has lower collateral effects and greater radiobiological effectiveness at the tumor site is that of hadrontherapy. This technique uses hadrons (protons or heavier nuclei) to deposit high doses at the tumor site that are very conformed, that is to say, limited to that area. The cost of this technique, however, is much higher than conventional photon or electron methods, precluding its use for many patients. It is also rarely available at hospitals and health and treatment centers. FIG. 1 shows a sketch comparing the relative depth dose of the most widely used radiotherapy techniques. This invention proposes the use of a device able to generate a convergent photon beam with advantages that are significantly greater than the conventional external radiotherapy technique and the hadrontherapy techniques, the latter catalogued as being those that provide better results. From a comparative point of view, conventional conformal radiotherapy techniques or IMRT (the latter being better): administer a greater superficial dose; are a greater risk to healthy organs; require fractioning and a more complex planning system; require more energy and, therefore, more costly bunkers; not all tumors are accessible; thus rendering the techniques less effective. The advantages of these techniques are that a greater volume is treated and the positioning system is simpler. FIG. 2 shows the fundamental difference between the conventional method, (a), and the convergent method (b). The convergent method, however, presents: lower surface dose, low dose in healthy organs; high dose in the tumor which does not require fractioning; simpler planning system; shorter treatment (one or two sessions); greater effectiveness and accessibility to most tumors; simpler refrigeration system; high energy is not required thus bunker shielding requirements are lower. The disadvantage is that, as the treated volume is smaller, a tumor scan and a more precise positioning system are required. The only external photon method that is comparable, quality-wise, to the convergent technique of the invention being proposed is the arc therapy technique, also known as Tomotherapy, using photons with a linear accelerator (LINAC) that generates electron beams to produce the required X-rays. Arc therapy emulates convergence by using an angular scan around the isocenter (tumor site). Despite longer sessions and equally complex planning, however, each beam is still essentially divergent and the doses in healthy organs are not insignificant. Like the other conventional LINAC techniques, several sessions are required. Similar results can be obtained using a robotic device called a “Cyberknife”. The hadrontherapy technique presents the following: a low surface dose and is highly effective as it deposits a high dose depth in a very small site (Bragg peak, see FIG. 1 ). Hadrons and ions have high radiobiological effectiveness (protons are 5 times more effective than photons) and complex positioning systems. However, a very complex installation is required, which includes a synchrotron able to accelerate particles to energies ranging from several hundred MeV to several GeV, high vacuum, and electrical and magnetic guide systems. Furthermore, the cost of a hadrontherapy system exceeds $100M USD. There are 28 hadrontherapy installations in the world's most developed nations and the technique continues to grow despite its high cost. Hadrontherapy is out of the question for Chile at present though Spain is evaluating the possibility of acquiring one of these installations in the next few years. Hadrontherapy has shown excellent results in patients with complex cancers as it is able to treat tumors that cannot be treated with photons. The cost of this therapy, however, means it is available to only a select few. The convergent method employed by the invention presented here delivers low surface dose and is highly effective, as it deposits a high depth dose in a very small area (“peak focus”). Photons have less radiobiological effectiveness, but the dose deposited at the focus peak site can be up to 100 times greater than the dose on the surface, despite the attenuation effect. This compensates for the photons' lower radiobiological effectiveness and generates an even lower relative dose on the surface and in the healthy organs than that which is obtained in hadrontherapy. The positioning system, however, must be more precise than that of conventional techniques. All of the above will allow for the treatment of complex cancer cases as with hadrontherapy but with a less complex installation. Furthermore, the cost of a LINAC plus a bunker and control building is in the $2 to 3 MUSD ranges, while a LINAC-adaptable convergence system may cost $0.5M USD or less, a noteworthy advantage in relation to the cost of a hadrontherapy installation which is almost two orders of magnitude greater. In this regard, a convergent system would function similarly to a hadrontherapy system but at a significantly lower cost. The first step taken prior to the development of this invention was the study of the effects of a photon beam's convergence on a specific material that was carried out by Monte Carlo Simulations (MCS) and theoretical calculations. FIG. 3 shows the curves of a depth dose corresponding to MCS and the theoretical results. Devices currently exist that achieve beam convergence with a divergent X-ray beam based on the total reflection principle. The divergent X-rays enter a cone-shaped capillary, and the beams travel the length of it by total reflection inside the capillary until they reach the end. The exit section is smaller than the entry section, thus allowing a greater intensity to be achieved. In order to attain a significant increase in intensity, a set of these cone-shaped capillaries set in parallels is used. This makes up what is known as a poli-capillary and allows the entry area to be increased. However, as these devices employ the total reflection principle, its use is only advantageous with X-rays with energies below 50 keV, which limits its application in radiotherapy equipment, where the X-ray energy is much greater than the aforementioned amount. There is currently a great variety of X-ray focusing devices that use not only the total reflection principle but diffraction and/or refraction as well, though all of them can be used for low energy X-rays (<50 keV). For example, in astronomy, an X-ray telescope (Chandra and equivalents) obtains X-ray images of the Universe, allowing us to see emission sources, including black holes. This is a large-scale device (several meters) that is based on the same total reflection principle and uses reflector plates and other materials. SUMMARY OF THE INVENTION After considering existing devices, which are limited to low energy, and the results obtained from studies that were performed, this innovative idea of an electron- and convergent X-ray-generating piece of equipment was developed, appropriate for low, medium and high energies (<0.1 MeV, 0.1-1.0 MeV and 1>MeV respectively). This would also be the only way to achieve X-ray beam convergence at energies within the application's range in radiotherapy techniques. When this beam is pointed virtually towards a water phantom or water equivalent, a depth dose profile can be obtained like the one shown in FIG. 4 for two different energies. These profiles were achieved using a MCS code. Other results attained by MCS are shown from FIGS. 5 to 8 . All the MCS that were carried out show that the convergent radiotherapy technique, as proposed with this invention, is noticeably better than the conventional techniques used to date. A very brief description of the positioning system for the various cases is given in this presentation of the invention. Directional arrows are also shown without providing further details, as that would not be part of the essence of this invention. Also, positioning systems are already available on the market. However, the various ways in which the invention must be adapted in each case shall be presented. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a relative depth dose for the different techniques used in radiotherapy. FIG. 2 a shows a diagram of the traditional X-ray radiotherapy. FIG. 2 b shows a diagram of a convergent X-ray radiotherapy. FIG. 3 shows a depth dose for a convergent photon beam at 0.4 MeV in a water phantom, compared to the theoretical results and MCS. FIG. 4 shows a comparison of two dose profiles for convergent photons from two MCS for focal points at 2 and 10 cm from the surface of the phantom. FIG. 5 shows a sectional view of a depth dose achieved by MCS for convergent photons, for a non-refined case. FIG. 6 shows a sectional view of a depth dose achieved by MCS for convergent photons, generated by the electrons that impact on an anode cap and then pass through a perforated cap-style poli-collimator similar to those proposed in this invention. FIG. 7 shows a profile of the energy deposited at low energy (per voxel unit) (Z=0, Y=0) with angular collimator acceptance: polar: 2 degrees and azimuthal: 2 degrees. E=4 MeV. FIG. 8 shows a profile of the energy deposited at high energy (per voxel unit) (Z=0, Y=0) with angular collimator acceptance: polar: 2 degrees and azimuthal: 2 degrees. E=4 MeV. FIG. 9 shows a sketch of the convergent electron beam generator element, which can be made up of more than one magnetic lens. FIG. 10 shows a sketch of an alternate configuration of the convergent electron beam generator element, which can be made up of an electrostatic element similar to cylinder lenses. FIG. 11 shows a sketch describing how the convergent photon beam is generated by the invention proposed here. FIG. 12 shows a sketch of the present invention's essential functional parts: electron disperser ( 1 ), set of magnet or electrostatic lens ( 2 ), anode cap ( 3 ), shielding ring support ( 4 ), poli-collimator ( 5 ), holes ( 6 ), optional second poli-collimator ( 7 ) and conical ring for penumbra ( 8 ). FIG. 13 shows a detailed description of some specific parts of the invention, including each of its parts: electron source coupler ( 9 ), electron entering window ( 10 ), cone-shaped shielding ( 11 ), vacuum connection I ( 12 ), ring-shaped support ( 13 ), cylindrical external housing ( 14 ), phase coupler ( 15 ), truncated cone ( 16 ), internal shielding ( 17 ), vacuum connection II ( 18 ) and front-end unit ( 19 ). FIGS. 14 a and 14 b show a sectional view and front view, respectively, of the front-end unit, comprising: an exit collimator with collimator support ( 20 ) and set superimposed diaphragms ( 21 ), light supporting plate ( 22 ), with positioning laser guide ( 23 ), position control sensors ( 24 ), and, and central laser ( 25 ). FIG. 15 shows a sectional view of an alternative configuration of the front-end unit, with interchangeable conical ring collimator ( 26 ). FIG. 16 shows a configuration of the present invention adapted to a typical LINAC, with: gantry ( 27 ), electron linear accelerator ( 28 ), convergent device ( 29 ), which constitutes the invention proposed here, and conventional head ( 30 ). FIG. 17 shows a configuration of the convergent device ( 29 ) adapted to a Cyberknife robotic system ( 31 ) and electron linear accelerator ( 28 ). FIG. 18 shows a configuration of the convergent device ( 29 ) adapted to a Tomotherapy system that comprises a rotation system ( 32 ) and electron linear accelerator ( 28 ). FIG. 19 shows an alternate configuration of the convergent device ( 29 ) being used for low energy application that is made up of electron cannon ( 33 ) comprised of: filament ( 34 ), concentrator cathode ( 35 ), and disperser anode ( 36 ). Additionally, a sensor system ( 37 ), with position sensors can be located on the patient's skin aimed to provide spatial positioning information; automatic systems based on the spatial position dedicated to control electro-mechanic devices. FIG. 20 sketches how photon/electron convergent exit beams are exchangeable by means of different cones: convergent device ( 29 ), phase coupler ( 15 ), vacuum ring seal ( 38 ), truncated cone ( 16 ) and empty truncated cone ( 39 ). DETAILED DESCRIPTION OF THE INVENTION The invention presented here consists of a device that generates a convergent electron and X-ray beam. First, an electron beam from electron cannon is needed. The electrons are accelerated in radiotherapy LINAC (or simply LINAC) by a series of stages until a flow of electrons with energy between 6 and 18 MeV is achieved. It can also be used for intermediate or low energy ranges generated solely by means of the electron cannon. As seen in FIG. 12 , the relatively collimated electron beam coming from the electron linear accelerator is first expanded by an electron disperser ( 1 ). The electrons are then focalized by the action of an appropriate set electro magnet or electrostatic lens controlled by electric current and/or voltage respectively ( 2 ). The electrons that emerge from the lens intercept the surface of an anode shaped as a curved (spherical, aspheric or parabolic) cap, which shall be referred to as an “anode cap” ( 3 ) and attached to shielding ring support ( 4 ). The anode cap's curvature radius defines the focal distance of the convergent system. As shown in FIG. 9 , the magnetic lens has an entrance lens body (c), a field concentrator housing (d) and electric conductors with a solenoid winding (e). The convergent electron beam generator element, in an alternative configuration of the invention, can also be made up of an electrostatic element that is similar to cylinder lenses. The first is grounded (f), the second cylinder is negatively polarized (g), and the third is also grounded (h) ( FIG. 10 ). The electronic lenses must be adjusted so that the electron beam impacts perpendicularly on the entire surface of the anode cap. As a result of the interaction of the electrons with the atoms that make up the anode's material, breaking radiation (known as bremsstrahlung), or X-rays in the material, is generated. As the incidence of the electrons occurs on the entire surface of the anode cap (i) (see FIG. 11 ), the bremsstrahlung X-ray emission phenomenon will occur isotropically on the entire anode cap. Bremsstrahlung is generated at each point on the cap. According to FIG. 11 , the X-rays that exit the anode cap have an angular non-isotropic distribution, with a greater intensity in the electrons' incidence direction and an angular divergence inversely proportional to the incident electron's energy (k). The X-rays are then collimated by a spherical poli-collimator ( 5 ) (similar to the anode cap) with tens, or hundreds of small holes ( 6 ) having millimetric or submillimetric dimensions according to the requirements. These holes point in the direction of the focal point, which represents the geometrical convergence focus of the anode cap, i.e. “anode cap focal point” (n). The X-rays that are able to pass through these holes will exit with a much lower angular dispersion than they had at the anode cap ( 3 ) exit. The rest are absorbed into the material, thus generating a convergent photon beam, with its greatest intensity concentrated at the focal point. The definition of the focal point of this convergent photon beam may be improved by inserting an optional second poli-collimator ( 7 ). This effect globally generates a radiation volume that mainly points towards the system's focal point with a significantly greater intensity of X-rays at the focal point (peak-focus), the magnitude of which will depend upon the energy of the electrons, the curvature radius of the anode cap ( 3 ), the anode cap's surface and the opening of the set of superimposed diaphragms that will be shown further on. The invention's essential parts are shown in FIG. 12 . Electrons coming from an electron source are dispersed by a small sheet (scattering foil) ( 1 ) in order to generate a flow of divergent electrons. The electrons are deflected according to the axis by a magnetic (or electrostatic) lens ( 2 ), thus generating a flow of convergent electrons (i) that is perpendicularly intercepted (j) by the anode cap ( 3 ), and a shielding ring support ( 4 ). The X-rays that are able to exit the thickness of the anode cap (k) are collimated by a poli-collimator ( 5 ) having small holes perforated, tens or hundreds, on its entire surface ( 6 ) that point in the direction of the focal point. The convergent X-ray beam (I) can be collimated once again (m) by an optional second poli-collimator ( 7 ). This collimator is surrounded by a concentric conical ring for penumbra ( 8 ). The poli-collimator can be either adhered to or separate from the anode cap. The material from which the polli-colimator is made is of a certain composition and thickness, such that the collimator is able to completely attenuate the X-rays that impact outside the collimator's holes and the holes can be either cylindrical or conical. FIG. 13 shows the invention as an apparatus in more detail. It has an electron source coupler ( 9 ), which allows the device to be attached to a specific LINAC (high energy) or any kind of electron cannon (low energy) by means of screws for example, as shown. Whichever the case, it is a piece that must adapt to the different devices available on the market. When considering LINAC as electron source, there is the electron entering window ( 10 ). Contrary, when using electron cannon as electron source it is not required the insertion of electron disperser ( 1 ) that acts as scattering foil. The electron beam enters a vacuum space contained by a cone-shaped shielding ( 11 ), with a vacuum connection I ( 12 ) and at the base of the cone there is a ring-shaped support ( 13 ) that attaches to the cylindrical external housing ( 14 ). Further down is a phase coupler ( 15 ) that separates the regions where electron and photon beams are transported. The photon region is made up of an external housing shaped like a truncated cone ( 16 ) that has internal shielding ( 17 ) with shielding ring support ( 4 ) and conical ring for penumbra ( 8 ) as well as a vacuum connection II ( 18 ) if required. Finally, there is a front-end unit ( 19 ) at the inferior end of the truncated cone ( 16 ). The details of front-end unit ( 19 ) are described below. FIGS. 14 a and 14 b show two views of the front-end unit ( 19 ), which is made up of: an exit collimator comprising by a collimator support ( 20 ) and a set of superimposed diaphragms ( 21 ). The collimator regulates field size at the incident surface trough the set of superimposed diaphragms placing one on top of the other, as sketched in Figure. In order to mark the entry field on the surface of the patient, there is a light supporting plate ( 22 ) made out of a low Z (atomic number) material, such as acrylic, with holes where positioning laser guide ( 23 ), are placed that point in the focal point's direction. These are located along a circumference on the border of the field diaphragm, enabling visibility of the entry field upon the patient's skin undergoing irradiation. Also position control sensors ( 24 ) are located in the light supporting plate. Finally, in order to locate central axis, the front-end unit has the small removable central laser ( 24 ). FIG. 15 shows a view of an alternate of the front-end unit in which diaphragms are replaced by a solid interchangeable conical ring collimator ( 26 ) that has a predefined field size. The surrounding positioning lasers ( 23 ), central laser ( 25 ) and position control sensors ( 24 ) can be incorporated to the light supporting plate. FIGS. 16, 17 and 18 illustrate how this invention could be adapted to apparatuses currently in use for external photon radiotherapy. FIG. 16 exhibits the invention adapted to a conventional LINAC, showing a gantry ( 27 ) and the electron linear accelerator ( 28 ). Figure includes also a sketch of the convergent device ( 29 ) proposed here that is joint firmly through electron source coupler ( 9 ), in the same location where the conventional head ( 30 ) is attached, as shown in FIG. 16 . The figure also sketches how the conventional head ( 30 ) and the convergent device can be exchanged. FIG. 17 shows a configuration of the convergent device ( 29 ) adapted to a Cyberknife: robotic system ( 31 ) that includes a, linear accelerator ( 28 ) and the convergent device. FIG. 18 displays a configuration of the convergent device ( 29 ) adapted to a Tomotherapy device that comprises a rotation system ( 32 ) an electron linear accelerator ( 28 ) and the convergent device ( 29 ). The above means that the convergent device ( 29 ) can be built a certain size so that it is adjustable to the dimensions of the currently commercially available technologies. FIG. 19 shows a prototype for electron sources with low energies (<1 MeV). This prototype is made up of the electron cannon ( 33 ) and the convergent device ( 29 ) being proposed. Typical electron cannons are comprised of a filament ( 34 ), a concentrator cathode ( 35 ) and disperser anode ( 36 ). The prototype is also equipped with sensor systems ( 37 ) for feedback positioning using the devices described above as well as sensors adhered to the patient's skin (similar to a bandage). Additional advantages that a unit such as this one has to offer are its noteworthy low cost, small size and fewer shield requirements, thus making external photon radiotherapy an effective, low-cost technique available to a greater number of people. Likewise the entire system, electron cannon and convergent device, constitutes an ensemble that becomes a stand-alone convergent beam device. Lastly, the description in FIG. 20 explains how the radiation modality of the proposed convergent device ( 29 ) can be simply converted to a convergent electron beam by exchanging through the phase coupler ( 15 ) the truncated cone ( 16 ) by empty truncate cone ( 39 ) that consists of a similar piece as 16 without anode and collimators, as shown.
A piece of scientific/technological equipment is presented for the generation of a convergent photon beam for radiotherapy or other applications. This equipment consists of adequately modifying the trajectory of an electron beam from a linear accelerator (LINAC) by applying magnetic and/or electric fields. These electrons perpendicularly impact the surface of a curved material that has a particular curvature ratio (anode), thus generating X-rays. The interaction of the electrons with the atoms of the anode's material generate X-rays with a non-isotropic angular-spatial distribution, with a greater concentration in the focal direction, which is defined by the geometry of the anode. A curved collimator with an adequate curvature ratio is attached to the back of the anode. The collimator is made up of an array of a great number of small holes that point toward the focal point. This device transmits X-rays solely in the focal direction. The Summary Figure presents a typical configuration of the invention that has been presented.
Identify the most important claim in the given context and summarize it
[ "CROSS-REFERENCE TO RELATED APPLICATIONS This application is a National Stage Application of PCT/IB2012/051983, filed 19 Apr. 2012, which claims benefit of Serial No. 898-2011, filed 20 Apr. 2011 in Chile and which applications are incorporated herein by reference.", "To the extent appropriate, a claim of priority is made to each of the above disclosed applications.", "BACKGROUND From the discovery of the X-ray in 1895 until now, the emission of a radiation ray, at any energy range, is essentially divergent and the intensity is a function of the distance between it and the emission source (inverse square law).", "This is due to the X-ray production mechanism;", "in other words, electrons that impact a target.", "There are currently several ways to generate X-ray beams, each with a determined source size and a specific, always-positive divergence.", "The X-ray beams employed in radiotherapy are divergent.", "The expected objective of radiotherapy is, by using X-rays, to achieve a high X-ray flow zone within a specific volume.", "These X-rays would then deposit their energy.", "The energy deposited per unit mass is known as dose in radiotherapy.", "Since the beam that is used is noticeably divergent, several beams (fields) aimed at the volume of interest must be employed.", "As is widely known, the depth dose for an X-ray beam is dependent on an exponential downward curve according to the depth, with a maximum value near the surface.", "A multi-field application allows for a maximum dose in the interest volume (tumor site), despite the fact that the dose values in the surrounding areas are lower than those at the tumor site.", "These dose values are significant as they have higher values than what is tolerable in some cases, which can prevent the use of an effective dose in the tumor.", "More refined techniques such as Intensity Modulated Radio Therapy (IMRT) or arc therapy improve and conform the maximum flow volume of X-rays, thus lowering dose levels in neighboring tissues and organs, though this decrease is not significant.", "A dose value decrease of up to 80% in tissues and organs near the interest zone has currently been achieved in relation to the dose in the interest zone.", "Treatment planning, however, continues to be complex.", "A decrease of collateral effects caused by radiation is always attempted, though their complete elimination is impossible.", "A radiotherapy technique that has lower collateral effects and greater radiobiological effectiveness at the tumor site is that of hadrontherapy.", "This technique uses hadrons (protons or heavier nuclei) to deposit high doses at the tumor site that are very conformed, that is to say, limited to that area.", "The cost of this technique, however, is much higher than conventional photon or electron methods, precluding its use for many patients.", "It is also rarely available at hospitals and health and treatment centers.", "FIG. 1 shows a sketch comparing the relative depth dose of the most widely used radiotherapy techniques.", "This invention proposes the use of a device able to generate a convergent photon beam with advantages that are significantly greater than the conventional external radiotherapy technique and the hadrontherapy techniques, the latter catalogued as being those that provide better results.", "From a comparative point of view, conventional conformal radiotherapy techniques or IMRT (the latter being better): administer a greater superficial dose;", "are a greater risk to healthy organs;", "require fractioning and a more complex planning system;", "require more energy and, therefore, more costly bunkers;", "not all tumors are accessible;", "thus rendering the techniques less effective.", "The advantages of these techniques are that a greater volume is treated and the positioning system is simpler.", "FIG. 2 shows the fundamental difference between the conventional method, (a), and the convergent method (b).", "The convergent method, however, presents: lower surface dose, low dose in healthy organs;", "high dose in the tumor which does not require fractioning;", "simpler planning system;", "shorter treatment (one or two sessions);", "greater effectiveness and accessibility to most tumors;", "simpler refrigeration system;", "high energy is not required thus bunker shielding requirements are lower.", "The disadvantage is that, as the treated volume is smaller, a tumor scan and a more precise positioning system are required.", "The only external photon method that is comparable, quality-wise, to the convergent technique of the invention being proposed is the arc therapy technique, also known as Tomotherapy, using photons with a linear accelerator (LINAC) that generates electron beams to produce the required X-rays.", "Arc therapy emulates convergence by using an angular scan around the isocenter (tumor site).", "Despite longer sessions and equally complex planning, however, each beam is still essentially divergent and the doses in healthy organs are not insignificant.", "Like the other conventional LINAC techniques, several sessions are required.", "Similar results can be obtained using a robotic device called a “Cyberknife.”", "The hadrontherapy technique presents the following: a low surface dose and is highly effective as it deposits a high dose depth in a very small site (Bragg peak, see FIG. 1 ).", "Hadrons and ions have high radiobiological effectiveness (protons are 5 times more effective than photons) and complex positioning systems.", "However, a very complex installation is required, which includes a synchrotron able to accelerate particles to energies ranging from several hundred MeV to several GeV, high vacuum, and electrical and magnetic guide systems.", "Furthermore, the cost of a hadrontherapy system exceeds $100M USD.", "There are 28 hadrontherapy installations in the world's most developed nations and the technique continues to grow despite its high cost.", "Hadrontherapy is out of the question for Chile at present though Spain is evaluating the possibility of acquiring one of these installations in the next few years.", "Hadrontherapy has shown excellent results in patients with complex cancers as it is able to treat tumors that cannot be treated with photons.", "The cost of this therapy, however, means it is available to only a select few.", "The convergent method employed by the invention presented here delivers low surface dose and is highly effective, as it deposits a high depth dose in a very small area (“peak focus”).", "Photons have less radiobiological effectiveness, but the dose deposited at the focus peak site can be up to 100 times greater than the dose on the surface, despite the attenuation effect.", "This compensates for the photons'", "lower radiobiological effectiveness and generates an even lower relative dose on the surface and in the healthy organs than that which is obtained in hadrontherapy.", "The positioning system, however, must be more precise than that of conventional techniques.", "All of the above will allow for the treatment of complex cancer cases as with hadrontherapy but with a less complex installation.", "Furthermore, the cost of a LINAC plus a bunker and control building is in the $2 to 3 MUSD ranges, while a LINAC-adaptable convergence system may cost $0.5M USD or less, a noteworthy advantage in relation to the cost of a hadrontherapy installation which is almost two orders of magnitude greater.", "In this regard, a convergent system would function similarly to a hadrontherapy system but at a significantly lower cost.", "The first step taken prior to the development of this invention was the study of the effects of a photon beam's convergence on a specific material that was carried out by Monte Carlo Simulations (MCS) and theoretical calculations.", "FIG. 3 shows the curves of a depth dose corresponding to MCS and the theoretical results.", "Devices currently exist that achieve beam convergence with a divergent X-ray beam based on the total reflection principle.", "The divergent X-rays enter a cone-shaped capillary, and the beams travel the length of it by total reflection inside the capillary until they reach the end.", "The exit section is smaller than the entry section, thus allowing a greater intensity to be achieved.", "In order to attain a significant increase in intensity, a set of these cone-shaped capillaries set in parallels is used.", "This makes up what is known as a poli-capillary and allows the entry area to be increased.", "However, as these devices employ the total reflection principle, its use is only advantageous with X-rays with energies below 50 keV, which limits its application in radiotherapy equipment, where the X-ray energy is much greater than the aforementioned amount.", "There is currently a great variety of X-ray focusing devices that use not only the total reflection principle but diffraction and/or refraction as well, though all of them can be used for low energy X-rays (<50 keV).", "For example, in astronomy, an X-ray telescope (Chandra and equivalents) obtains X-ray images of the Universe, allowing us to see emission sources, including black holes.", "This is a large-scale device (several meters) that is based on the same total reflection principle and uses reflector plates and other materials.", "SUMMARY OF THE INVENTION After considering existing devices, which are limited to low energy, and the results obtained from studies that were performed, this innovative idea of an electron- and convergent X-ray-generating piece of equipment was developed, appropriate for low, medium and high energies (<0.1 MeV, 0.1-1.0 MeV and 1>MeV respectively).", "This would also be the only way to achieve X-ray beam convergence at energies within the application's range in radiotherapy techniques.", "When this beam is pointed virtually towards a water phantom or water equivalent, a depth dose profile can be obtained like the one shown in FIG. 4 for two different energies.", "These profiles were achieved using a MCS code.", "Other results attained by MCS are shown from FIGS. 5 to 8 .", "All the MCS that were carried out show that the convergent radiotherapy technique, as proposed with this invention, is noticeably better than the conventional techniques used to date.", "A very brief description of the positioning system for the various cases is given in this presentation of the invention.", "Directional arrows are also shown without providing further details, as that would not be part of the essence of this invention.", "Also, positioning systems are already available on the market.", "However, the various ways in which the invention must be adapted in each case shall be presented.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a relative depth dose for the different techniques used in radiotherapy.", "FIG. 2 a shows a diagram of the traditional X-ray radiotherapy.", "FIG. 2 b shows a diagram of a convergent X-ray radiotherapy.", "FIG. 3 shows a depth dose for a convergent photon beam at 0.4 MeV in a water phantom, compared to the theoretical results and MCS.", "FIG. 4 shows a comparison of two dose profiles for convergent photons from two MCS for focal points at 2 and 10 cm from the surface of the phantom.", "FIG. 5 shows a sectional view of a depth dose achieved by MCS for convergent photons, for a non-refined case.", "FIG. 6 shows a sectional view of a depth dose achieved by MCS for convergent photons, generated by the electrons that impact on an anode cap and then pass through a perforated cap-style poli-collimator similar to those proposed in this invention.", "FIG. 7 shows a profile of the energy deposited at low energy (per voxel unit) (Z=0, Y=0) with angular collimator acceptance: polar: 2 degrees and azimuthal: 2 degrees.", "E=4 MeV.", "FIG. 8 shows a profile of the energy deposited at high energy (per voxel unit) (Z=0, Y=0) with angular collimator acceptance: polar: 2 degrees and azimuthal: 2 degrees.", "E=4 MeV.", "FIG. 9 shows a sketch of the convergent electron beam generator element, which can be made up of more than one magnetic lens.", "FIG. 10 shows a sketch of an alternate configuration of the convergent electron beam generator element, which can be made up of an electrostatic element similar to cylinder lenses.", "FIG. 11 shows a sketch describing how the convergent photon beam is generated by the invention proposed here.", "FIG. 12 shows a sketch of the present invention's essential functional parts: electron disperser ( 1 ), set of magnet or electrostatic lens ( 2 ), anode cap ( 3 ), shielding ring support ( 4 ), poli-collimator ( 5 ), holes ( 6 ), optional second poli-collimator ( 7 ) and conical ring for penumbra ( 8 ).", "FIG. 13 shows a detailed description of some specific parts of the invention, including each of its parts: electron source coupler ( 9 ), electron entering window ( 10 ), cone-shaped shielding ( 11 ), vacuum connection I ( 12 ), ring-shaped support ( 13 ), cylindrical external housing ( 14 ), phase coupler ( 15 ), truncated cone ( 16 ), internal shielding ( 17 ), vacuum connection II ( 18 ) and front-end unit ( 19 ).", "FIGS. 14 a and 14 b show a sectional view and front view, respectively, of the front-end unit, comprising: an exit collimator with collimator support ( 20 ) and set superimposed diaphragms ( 21 ), light supporting plate ( 22 ), with positioning laser guide ( 23 ), position control sensors ( 24 ), and, and central laser ( 25 ).", "FIG. 15 shows a sectional view of an alternative configuration of the front-end unit, with interchangeable conical ring collimator ( 26 ).", "FIG. 16 shows a configuration of the present invention adapted to a typical LINAC, with: gantry ( 27 ), electron linear accelerator ( 28 ), convergent device ( 29 ), which constitutes the invention proposed here, and conventional head ( 30 ).", "FIG. 17 shows a configuration of the convergent device ( 29 ) adapted to a Cyberknife robotic system ( 31 ) and electron linear accelerator ( 28 ).", "FIG. 18 shows a configuration of the convergent device ( 29 ) adapted to a Tomotherapy system that comprises a rotation system ( 32 ) and electron linear accelerator ( 28 ).", "FIG. 19 shows an alternate configuration of the convergent device ( 29 ) being used for low energy application that is made up of electron cannon ( 33 ) comprised of: filament ( 34 ), concentrator cathode ( 35 ), and disperser anode ( 36 ).", "Additionally, a sensor system ( 37 ), with position sensors can be located on the patient's skin aimed to provide spatial positioning information;", "automatic systems based on the spatial position dedicated to control electro-mechanic devices.", "FIG. 20 sketches how photon/electron convergent exit beams are exchangeable by means of different cones: convergent device ( 29 ), phase coupler ( 15 ), vacuum ring seal ( 38 ), truncated cone ( 16 ) and empty truncated cone ( 39 ).", "DETAILED DESCRIPTION OF THE INVENTION The invention presented here consists of a device that generates a convergent electron and X-ray beam.", "First, an electron beam from electron cannon is needed.", "The electrons are accelerated in radiotherapy LINAC (or simply LINAC) by a series of stages until a flow of electrons with energy between 6 and 18 MeV is achieved.", "It can also be used for intermediate or low energy ranges generated solely by means of the electron cannon.", "As seen in FIG. 12 , the relatively collimated electron beam coming from the electron linear accelerator is first expanded by an electron disperser ( 1 ).", "The electrons are then focalized by the action of an appropriate set electro magnet or electrostatic lens controlled by electric current and/or voltage respectively ( 2 ).", "The electrons that emerge from the lens intercept the surface of an anode shaped as a curved (spherical, aspheric or parabolic) cap, which shall be referred to as an “anode cap”", "( 3 ) and attached to shielding ring support ( 4 ).", "The anode cap's curvature radius defines the focal distance of the convergent system.", "As shown in FIG. 9 , the magnetic lens has an entrance lens body (c), a field concentrator housing (d) and electric conductors with a solenoid winding (e).", "The convergent electron beam generator element, in an alternative configuration of the invention, can also be made up of an electrostatic element that is similar to cylinder lenses.", "The first is grounded (f), the second cylinder is negatively polarized (g), and the third is also grounded (h) ( FIG. 10 ).", "The electronic lenses must be adjusted so that the electron beam impacts perpendicularly on the entire surface of the anode cap.", "As a result of the interaction of the electrons with the atoms that make up the anode's material, breaking radiation (known as bremsstrahlung), or X-rays in the material, is generated.", "As the incidence of the electrons occurs on the entire surface of the anode cap (i) (see FIG. 11 ), the bremsstrahlung X-ray emission phenomenon will occur isotropically on the entire anode cap.", "Bremsstrahlung is generated at each point on the cap.", "According to FIG. 11 , the X-rays that exit the anode cap have an angular non-isotropic distribution, with a greater intensity in the electrons'", "incidence direction and an angular divergence inversely proportional to the incident electron's energy (k).", "The X-rays are then collimated by a spherical poli-collimator ( 5 ) (similar to the anode cap) with tens, or hundreds of small holes ( 6 ) having millimetric or submillimetric dimensions according to the requirements.", "These holes point in the direction of the focal point, which represents the geometrical convergence focus of the anode cap, i.e. “anode cap focal point”", "(n).", "The X-rays that are able to pass through these holes will exit with a much lower angular dispersion than they had at the anode cap ( 3 ) exit.", "The rest are absorbed into the material, thus generating a convergent photon beam, with its greatest intensity concentrated at the focal point.", "The definition of the focal point of this convergent photon beam may be improved by inserting an optional second poli-collimator ( 7 ).", "This effect globally generates a radiation volume that mainly points towards the system's focal point with a significantly greater intensity of X-rays at the focal point (peak-focus), the magnitude of which will depend upon the energy of the electrons, the curvature radius of the anode cap ( 3 ), the anode cap's surface and the opening of the set of superimposed diaphragms that will be shown further on.", "The invention's essential parts are shown in FIG. 12 .", "Electrons coming from an electron source are dispersed by a small sheet (scattering foil) ( 1 ) in order to generate a flow of divergent electrons.", "The electrons are deflected according to the axis by a magnetic (or electrostatic) lens ( 2 ), thus generating a flow of convergent electrons (i) that is perpendicularly intercepted (j) by the anode cap ( 3 ), and a shielding ring support ( 4 ).", "The X-rays that are able to exit the thickness of the anode cap (k) are collimated by a poli-collimator ( 5 ) having small holes perforated, tens or hundreds, on its entire surface ( 6 ) that point in the direction of the focal point.", "The convergent X-ray beam (I) can be collimated once again (m) by an optional second poli-collimator ( 7 ).", "This collimator is surrounded by a concentric conical ring for penumbra ( 8 ).", "The poli-collimator can be either adhered to or separate from the anode cap.", "The material from which the polli-colimator is made is of a certain composition and thickness, such that the collimator is able to completely attenuate the X-rays that impact outside the collimator's holes and the holes can be either cylindrical or conical.", "FIG. 13 shows the invention as an apparatus in more detail.", "It has an electron source coupler ( 9 ), which allows the device to be attached to a specific LINAC (high energy) or any kind of electron cannon (low energy) by means of screws for example, as shown.", "Whichever the case, it is a piece that must adapt to the different devices available on the market.", "When considering LINAC as electron source, there is the electron entering window ( 10 ).", "Contrary, when using electron cannon as electron source it is not required the insertion of electron disperser ( 1 ) that acts as scattering foil.", "The electron beam enters a vacuum space contained by a cone-shaped shielding ( 11 ), with a vacuum connection I ( 12 ) and at the base of the cone there is a ring-shaped support ( 13 ) that attaches to the cylindrical external housing ( 14 ).", "Further down is a phase coupler ( 15 ) that separates the regions where electron and photon beams are transported.", "The photon region is made up of an external housing shaped like a truncated cone ( 16 ) that has internal shielding ( 17 ) with shielding ring support ( 4 ) and conical ring for penumbra ( 8 ) as well as a vacuum connection II ( 18 ) if required.", "Finally, there is a front-end unit ( 19 ) at the inferior end of the truncated cone ( 16 ).", "The details of front-end unit ( 19 ) are described below.", "FIGS. 14 a and 14 b show two views of the front-end unit ( 19 ), which is made up of: an exit collimator comprising by a collimator support ( 20 ) and a set of superimposed diaphragms ( 21 ).", "The collimator regulates field size at the incident surface trough the set of superimposed diaphragms placing one on top of the other, as sketched in Figure.", "In order to mark the entry field on the surface of the patient, there is a light supporting plate ( 22 ) made out of a low Z (atomic number) material, such as acrylic, with holes where positioning laser guide ( 23 ), are placed that point in the focal point's direction.", "These are located along a circumference on the border of the field diaphragm, enabling visibility of the entry field upon the patient's skin undergoing irradiation.", "Also position control sensors ( 24 ) are located in the light supporting plate.", "Finally, in order to locate central axis, the front-end unit has the small removable central laser ( 24 ).", "FIG. 15 shows a view of an alternate of the front-end unit in which diaphragms are replaced by a solid interchangeable conical ring collimator ( 26 ) that has a predefined field size.", "The surrounding positioning lasers ( 23 ), central laser ( 25 ) and position control sensors ( 24 ) can be incorporated to the light supporting plate.", "FIGS. 16, 17 and 18 illustrate how this invention could be adapted to apparatuses currently in use for external photon radiotherapy.", "FIG. 16 exhibits the invention adapted to a conventional LINAC, showing a gantry ( 27 ) and the electron linear accelerator ( 28 ).", "Figure includes also a sketch of the convergent device ( 29 ) proposed here that is joint firmly through electron source coupler ( 9 ), in the same location where the conventional head ( 30 ) is attached, as shown in FIG. 16 .", "The figure also sketches how the conventional head ( 30 ) and the convergent device can be exchanged.", "FIG. 17 shows a configuration of the convergent device ( 29 ) adapted to a Cyberknife: robotic system ( 31 ) that includes a, linear accelerator ( 28 ) and the convergent device.", "FIG. 18 displays a configuration of the convergent device ( 29 ) adapted to a Tomotherapy device that comprises a rotation system ( 32 ) an electron linear accelerator ( 28 ) and the convergent device ( 29 ).", "The above means that the convergent device ( 29 ) can be built a certain size so that it is adjustable to the dimensions of the currently commercially available technologies.", "FIG. 19 shows a prototype for electron sources with low energies (<1 MeV).", "This prototype is made up of the electron cannon ( 33 ) and the convergent device ( 29 ) being proposed.", "Typical electron cannons are comprised of a filament ( 34 ), a concentrator cathode ( 35 ) and disperser anode ( 36 ).", "The prototype is also equipped with sensor systems ( 37 ) for feedback positioning using the devices described above as well as sensors adhered to the patient's skin (similar to a bandage).", "Additional advantages that a unit such as this one has to offer are its noteworthy low cost, small size and fewer shield requirements, thus making external photon radiotherapy an effective, low-cost technique available to a greater number of people.", "Likewise the entire system, electron cannon and convergent device, constitutes an ensemble that becomes a stand-alone convergent beam device.", "Lastly, the description in FIG. 20 explains how the radiation modality of the proposed convergent device ( 29 ) can be simply converted to a convergent electron beam by exchanging through the phase coupler ( 15 ) the truncated cone ( 16 ) by empty truncate cone ( 39 ) that consists of a similar piece as 16 without anode and collimators, as shown." ]
TECHNICAL FIELD This invention relates to input circuitry, and more specifically, to a fast input buffer circuit which protects deep sub-micron complementary metal-oxide semiconductor (CMOS) transistors from overvoltage stress. BACKGROUND OF THE RELATED ART Input circuits have been incorporated into chip technologies for many years to provide fast input buffers which protect deep sub-micron CMOS transistors from overvoltage stress. Three such prior art input buffer circuits are shown in FIGS. 1A-C. The circuit 1 in FIG. 1A has two field effect transistors (FETs) 100 a , 100 b . Field effect transistor 100 a is an n-type field effect transistor, whereas FET 100 b is a p-type field effect transistor. An input pad 110 is connected to the drain terminal of FET 100 a . The gate terminal of FET 100 a is connected to voltage source V DD . The source terminal of FET 100 a is connected to a voltage restoring circuit 120 , in the form of FET 100 b having its gate and source terminals coupled through an inverter 130 . The drain terminal of FET 100 b is connected to a power supply V DD . Further, two inverters 130 are connected in series and coupled to the source terminal of FET 100 b. A problem with the input circuit of FIG. 1A is that the voltage restoring circuit 120 conflicts with external pull-down resistors (not shown), which slow the speed and effectiveness of the circuit. The voltage restoring circuit 120 “pulls-up” the voltage to a “strong” HIGH logic level when FET 100 b is switched ON. The large impedance of the external resistors (not shown) oppose the effectiveness of the voltage restoring circuit 120 to produce this “strong” HIGH logic level. Another prior art input circuit is shown in FIG. 1 B. The circuit 2 of FIG. 1B is composed of an input pad 110 connected to the drain terminal of FET 100 a . The gate terminal of FET 100 a is connected to a voltage source V DD . The source terminal of FET 100 a is connected to series connected inverters 130 a , 130 b , and output Y is generated. This transistor 100 a plays an important role in the operations of the circuit 2 of FIG. 1 B. For example, if the transistor 100 a was not included, then when the input pad 110 is powered up, e.g. to five volts, the gate-to-source voltage on the n-type FET (not shown) of the inverter 130 a will be five volts and such n-type FET would pull the output of the inverter 130 a to ground. This would cause the p-type FET (not shown) of the inverter 130 a to have a gate-to-drain voltage of five volts. For deep submicron architecture neither of these results would be acceptable. With the inclusion of FET 100 a , however, the voltage at node A will never rise above the voltage on the gate terminal of FET 100 a less its threshold drop (for DC conditions and long settling times, the threshold may be large). Therefore, the voltage at node A will be less than the internal voltage V DD . Hence, the voltages across transistor 100 a and the n-type and p-type FETs (not shown) of the inverter 130 a are maintained in a range to achieve reasonable long-term reliability. The circuit 2 of FIG. 1B does not have the conflict disadvantage characteristic of circuit 1 of FIG. 1A, however, it has the disadvantage of leaking DC current because the p-channel device (not shown) in inverter 130 a is never completely turned off. A third prior art input circuit is shown in FIG. 1 C. The circuit 3 of FIG. 1C is composed of a pad input 110 connected to the drain terminal of FET 100 a . The gate terminal of FET 100 a is connected to a voltage source V DD . The source terminal of FET 100 a is connected to a CMOS inverter 140 . This CMOS inverter 140 is composed of an n-type FET 100 c and a p-type FET 100 d. The drain terminal of FET 100 d is connected to a diode 120 a , which is a p-type FET 100 e , having its gate and source terminals coupled together. The drain of FET 100 e is connected to a voltage source V DD . The output of the CMOS inverter 140 is connected to voltage restoring circuit 120 , which is FET 100 b having its gate and source terminals coupled through an inverter 130 . The drain of FET 100 b is connected to a voltage source V DD . Further, another inverter 130 is coupled to the source terminal of FET 100 b. Although the circuit 3 in FIG. 1C avoids the disadvantages of the circuits shown in FIGS. 1A and 1B, the circuit 3 of FIG. 1C is slow. Furthermore, it also has a natural magnitude hysteresis. This hysteresis will slow down the AC performance, but for any input, the output results will consistently be the same. Furthermore, to ensure threshold voltages and reasonable speeds, the sizes of p-type FETs 100 d and 100 e must be made large. The reason for the dimensional differences between the n-type and p-type FETs stems from the characteristic differences between the devices. The relationship between PMOS and NMOS transistors is such that for devices having the same dimensions, the current in a PMOS transistor is less than half of that in an NMOS device and the ON resistance of a p-channel MOSFET is nearly three times that for an n-channel MOSFET. Both circuits 1 and 3 represented in FIGS. 1A and 1C inherently have a large amount of hysteresis (one-ended hysteresis). To meet the 0.8 volt “low” and two volt “high” thresholds (for 3.3 volt systems), the propagation times from low-to-high and from high-to-low will have a large amount of skew between them. Alternatively, to achieve the same values of current and ON resistance as in an NMOS transistor, the channel width/length ratio must be increased to account for the lower hole mobility. This results in PMOS devices requiring nearly three times the area of an equivalent NMOS device. It is thus desirable to provide a fast input buffer which protects deep sub-micron CMOS transistors from overvoltage stress with minimal DC power requirements. Furthermore, it is desirable to provide a fast input buffer which protects deep sub-micron CMOS transistors from overvoltage stress which has no unusual bus loading and is faster than current I/O circuitry. It is also desirable to provide a fast input buffer which protects deep sub-micron CMOS transistors from overvoltage stress which meets transistor-transistor logic (TTL) thresholds and has symmetrical response times for fast propagation times from LOW logic level to HIGH logic level (T PLH ) and from HIGH logic level to LOW logic level (T PHL ). SUMMARY OF THE INVENTION An apparatus including an overvoltage protection circuit is provided that comprises an input terminal configured to convey an input voltage, an output terminal configured to convey an output voltage, a buffer circuit, coupled between the input terminal and the output terminal, configured to receive and buffer the input voltage and in accordance therewith provide the output voltage, and a voltage sensing circuit, coupled to the input terminal and the buffer circuit, configured to sense the input voltage and in accordance therewith maintain the buffer circuit in a predetermined voltage range. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a conventional input circuit. FIG. 1B is another conventional input circuit. FIG. 1C is yet another conventional input circuit. FIG. 2 is an input circuit in accordance with one embodiment of the present invention. FIG. 3 is an input circuit in accordance with another embodiment of the present invention. FIG. 4 is an input circuit in accordance with yet another embodiment of the present invention. FIG. 5 is an input circuit in accordance with still another embodiment of the present invention. FIG. 6A is an input circuit in accordance with yet still another embodiment of the present invention. FIG. 6B is a timing diagram of the input circuit of FIG. 6A illustrating the effect of hysteresis on the circuit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The input circuit 20 of the present invention will now be explained with reference to FIGS. 2-4. FIG. 2 shows an input circuit 20 in accordance with one embodiment of the present invention. An input pad 200 is connected to the anode of diode 210 a . The cathode of diode 210 a is connected to a voltage source V DDESD . Another diode 210 b has its cathode connected to input pad 200 . The anode of diode 210 b is connected to a voltage source V SSIO . Briefly, these diodes 210 a , 210 b serve to protect the circuit 20 from high voltage “spikes,” by discharging the extremely high voltage to the “ESD” and “IO” protection circuits (not shown). Therefore, the circuit 20 will not be damaged by these extremely high voltage “spikes.” In the circuit 20 , node 5 will have a full voltage range from V DD to 0V. The voltage on node 6 will range between 0V to V DD −1V THN . That is, when the input from the pad 200 is HIGH, the source potential of FET 220 a will be larger than the gate potential, i.e. V GS <V T , causing the transistor 220 a to be OFF (the voltage at node 6 will therefore be V DD −1V THN ). However, when the pad 200 input is LOW, the source terminal of FET 220 a will be at a lower potential than the gate terminal, i.e. V GS >V T , and FET 220 a will be ON, thus, the voltage at node 6 will be 0V. Therefore, as explained above, when the pad 200 input is HIGH, the voltage at node 6 will be HIGH, switching ON transistors 220 b and 220 e . Therefore, the voltage at node 5 will be 0V and the voltage at node 7 will be charged to V DD −2V THN . When the pad 200 input is LOW, the voltage at node 6 will be LOW and transistor 220 c will be switched ON. Furthermore, since the input is LOW, transistor 220 d will be switched ON. Thus, the voltage at node 5 will swing to V DD . The voltage at node 7 will swing to V DD . Therefore, FET 220 a prevents overvoltage on the gate to source terminal voltage of FET 220 b by ensuring the largest voltage swing at node 6 will be no greater than V DD −1V THN . Furthermore, as described above node 7 is charged up when the pad input 200 is HIGH. Therefore, an overvoltage problem across the gate to drain terminal voltage of FET 220 d is avoided. The overvoltage protection circuit is thus provided with an internal overvoltage protection. In other words, not only is the buffer circuit protected from overvoltage stress, but the voltage sensing circuit is configured in a way to protect itself from overvoltage stress. Thus, this circuit solves the overvoltage problem inherent in many input circuits and performs faster than conventional overvoltage protection circuits. For example, referring again to FIGS. 1A and 1C, such conventional circuits inherently have a lot of hysteresis (one-ended hysteresis). As an example, for 3.3V systems, the 0.8V LOW and 2V HIGH voltage magnitudes indicate the voltage magnitudes at which these circuits will interpret a state change. For example, an input voltage between the ranges of 0.8V and 2V would be interpreted to be that of the previous state. However, any input voltage below 0.8V will be interpreted as a strong logic LOW. Likewise, any input voltage above 2V will be interpreted as a strong logic HIGH. Thus, the propagation times from low-to-high and from high-to-low will have a large amount of skew between them due to this “hysteresis window” (low-to-high of approximately 0.9 ns and high-to-low of approximately 4.5 ns). Optimal timing would be with near similar propagation times from low-to-high and from high-to-low. As a result of the addition of the voltage sensing circuit component to the circuit of FIG. 2, similar propagation times from low-to-high and from high-to-low, that are partially a function of slow ramp time, can be achieved. Moreover, these times are generally of about half the propagation times from low-to-high and from high-to-low, respectively, of conventional overvoltage circuits. Thus, the circuit of FIG. 2 solves the overvoltage problem inherent in many input circuits and performs faster than conventional overvoltage protection circuits. FIG. 3 shows a second embodiment of the input circuit 30 of the present invention with a sleep mode. The sleep mode provides a method of controlling the output of the circuit irrespective of the input. An example of how this is accomplished will be explained later. The differences in circuit structure between the circuits of FIGS. 2 and 3 will now be explained with like components referenced by like reference numbers. Circuit 30 of FIG. 3 is similar to circuit 20 of FIG. 2 except for the addition of two FETs 220 f and 220 g . FET 220 f is an n-type field effect transistor, whereas FET 220 g is a p-type field effect transistor. FET 220 f has its drain terminal connected, in series, to the drain terminal of FET 220 c . The source terminal of FET 220 f is connected to the drain terminal of FET 220 b . The gate terminal of FET 220 f is connected to the sleep control signal SLEEP_Z. FET 220 g has its drain terminal connected to the drain terminals of FETs 220 c and 220 f . The source terminal of FET 220 g is connected to a voltage source V DD . The gate terminal of FET 220 g is connected to the sleep control signal SLEEP_Z. Operation of the circuit 30 of FIG. 3 is such that the output Y can only be HIGH, i.e. logic level “1,” when both pad input 200 is HIGH and SLEEP_Z is HIGH. That is, the input circuit 30 is controlled by SLEEP_Z. For example, if SLEEP_Z is HIGH and pad input 200 is LOW, output Y will be LOW. If SLEEP_Z is HIGH and pad input 200 is HIGH, output Y will be HIGH. If SLEEP_Z is LOW, then regardless of the logic level of pad input 200 , output Y will always be LOW. FIG. 4 is another embodiment 40 of the input circuit 40 of the present invention with overvoltage protection, sleep mode and hysteresis. The differences in circuit structure between the circuits of FIGS. 2, 3 and 4 will be explained with reference to like components indicated by like reference numbers. Circuit 40 is similar to the circuit 30 of FIG. 3 except for the addition of two FETs 220 h and 220 i . FET 220 h is an n-type field effect transistor, whereas FET 220 i is a p-type field effect transistor. FET 220 h has its source terminal connected to the connection of the source terminal of FET 220 f and the drain terminal of FET 220 b . The drain terminal of FET 220 h is connected to a voltage source V DD . The gate terminals of FETs 220 h and 220 i are connected to node 5 . The source terminal of FET 220 i is connected to a voltage source V SS . The drain terminal of FET 220 i is connected to the common node of the source terminals of FETs 220 c and 220 e and the drain terminal of FET 220 d (node 7 ). Thus, operation of the circuit of FIG. 4 is as that of the circuit of FIGS. 2 and 3, with the addition of noise tolerance. That is, the hysteresis elements, i.e. FETs 220 h and 220 i provide a noise tolerance to the circuit. Typically, the input from the pad 200 will not have “clean” rise and fall times. Instead, these signals will have a “jitter” effect, which is interpreted as noise. In this circuit, the hysteresis window is approximately 500 mV. Thus, the circuit will interpret an input voltage between the ranges of 1.1V to 1.6V to be that of the previous state. However, any input voltage below 1.1V will be interpreted as a strong logic LOW. Likewise, any input voltage above 1.6V will be interpreted as a strong logic HIGH. It should be noted that these voltage thresholds are merely an example of one embodiment. It is possible to alter both the amount of hysteresis and the absolute high and low thresholds. For example, by resizing transistors 220 d , 220 c , 220 f , 220 b , 220 i and 220 h , the amount of hysteresis can be changed, as well as the actual trip points for a high or low threshold. Referring again to FIG. 4, depending upon the potential at the output of the inverter (node 5 ), that potential may be either “high” enough to turn FET 220 h ON, or “low” enough to turn FET 220 i ON. Since the drain terminal of FET 220 h is connected to V DD , if the output potential is “high” enough to raise the gate-to-source voltage of FET 220 h above the threshold voltage, then FET 220 h will turn ON and effectively pull node 5 HIGH very quickly due to V DD being effectively applied to node 5 via FET 220 f and FET 220 h. In contrast, since the source terminal of FET 220 i is connected to V SS , if the output potential is “low” enough to drop the gate-to-source voltage of FET 220 i below the threshold voltage, then FET 220 i will turn ON and effectively pull node 5 LOW very quickly due to V SS being effectively applied to node 5 via FET 220 c and FET 220 i. Thus, a tolerance is introduced in an effort to compensate for noise jitter in the input voltage to produce a desired output logic level. Whereas the hysteresis circuit components, i.e., FET 220 h and FET 220 i , of FIG. 4 indirectly affect node 5 through FETs 220 f and 220 c , respectively, it is possible for the hysteresis circuit components to directly affect node 5 , such as is shown in FIG. 5 . Referring now to FIG. 5, in an alternative embodiment shown therein circuit 50 is similar to the circuit 30 of FIG. 3 except for the addition of FET 220 j and inverter 230 . The source terminal of FET 220 j is connected to a voltage source V DD . The drain terminal of FET 220 j is connected to node 5 . An inverter 230 is coupled between the gate terminal of FET 220 j and node 5 . Thus, hysteresis will affect the circuit 50 , much like described above with respect to the circuit 1 shown in FIG. 1 A. However, in the circuit 50 shown in FIG. 5, the hysteresis circuit components, i.e., FET 220 j and inverter 230 , directly affect node 5 as opposed to the indirect effect on node 5 that occurs in FIG. 4 . Perhaps the hysteresis effect can be best illustrated by FIGS. 6A and 6B. FIG. 6A illustrates an input circuit according to another embodiment of the invention. Specifically, the circuit 60 shown in FIG. 6A is almost identical to the circuit 40 of FIG. 4, except that FET 220 e is absent from the circuit 60 of FIG. 6A, merely for simplification purposes. FIG. 6B is a graphical representation of certain of the node voltages in FIG. 6 A. The three node voltages of interest are V(PAD) (the pad input voltage) 200 , output V(Y) 11 , and V(YBAR) (represented by node 5 in the Figure). The voltage plot represented in FIG. 6B is a voltage vs. time plot of a simulation of the circuit shown in FIG. 6 A. The voltage axis ranges from 0V to 3V and the time axis ranges from 0 s to 4 μs. Input signal V(PAD) is defined for the particular circuit, and will occur as defined, since it is represented as a perfect voltage source during simulation of the circuit of FIG. 6 A. V(PAD) is thus purposely described as a slow ramp, 20 μs rise time and 20 μs fall time, in order to view the actual hysteresis of the circuit. For the particular simulation of the circuit of FIG. 6A, the amount of hysteresis would be 0.53V (1.64V−1.1V=0.53V, measured by the state change voltage potentials) of hysteresis. Hysteresis usually does not affect the output voltage V(Y) maximum/minimum swing, but it does affect the input voltage required to trigger an output voltage transition. Therefore, the simulated peak rise time and fall time of the input voltage V(PAD) 200 are nearly identical, peaking at about 20 μs. However, as mentioned above, hysteresis can affect the simulated peak rise and fall times. As can be seen by reference number 201 (V(YBAR)), hysteresis affects both the maximum amplitude voltage V(PAD) 200 and the peak rise time (shown by the dotted line 8 ). For example, without hysteresis effects, the simulated peak rise and fall times are nearly identical, approximately 20 μs. With the inclusion of hysteresis effects, as represented by dotted line 201 , signal V(PADINT) 8 will equal V(PAD) 200 until V(PAD) 200 rises above V DD −V TH22a , at which point V(PADINT) 8 will no longer follow V(PAD) 200 , and the simulated peak will occur at the 22 μs point, thereby making the rise time approximately 2 μs slower and the fall time approximately 2 μs faster. However, hysteresis will not affect the points at which the circuit output will effectively change states. As described above, the circuit will interpret an input voltage between the ranges of 1.1V to 1.6V to be that of the previous state. However, any input voltage below 1.1V will be interpreted as a strong logic LOW. Likewise, any input voltage above 1.6V will be interpreted as a strong logic HIGH. These voltage ranges are indicated in the plot of FIG. 6B as the intersection points 9 A and 9 B. Thus, a tolerance is introduced in an effort to compensate for noise jitter in the input voltage to produce a desired output logic level. Although the above circuit has been described utilizing a connection of field effect transistors, similar results can be obtained by substituting bipolar junction transistors for the respective field effect transistors. The following examples, recited with reference to the circuit 20 shown in FIG. 2, will better illustrate the benefits and advantages of the fast overvoltage protected input circuit of the present invention. These examples are for illustrative purposes only and in no way are intended to be seen as limiting the invention to their description. EXAMPLE 1 0.35 micron process For a 0.35 micron process the maximum voltage V MAX between the gate to drain/source terminals is 4.2V. In this example, V DD is defined to be 3V and V PAD is defined to be 5.5V. As described above, the voltage on node 6 will range from 0V to V DD −1V THN . Therefore, the voltage on node 6 can be characterized as V A =V DD −1V THN =3V−0.7V=2.3V. The voltage at node 7 will swing from V DD to V DD −2V THN . Therefore, the voltage at node 7 can be characterized as V B =V DD −2V THN =3V−1.4V=1.6V. Thus, in this example, for FET 220 d , the gate to source voltage V GS =5.5V−3V=2.5V, and the gate to drain voltage V GD =5.5V−1.6V=3.9V. Thus, when the pad input voltage is HIGH, FET 220 d will be switched OFF. The source potential of FET 220 a will be large compared to the gate potential. Therefore, the voltage at node 7 is measured across FETs 220 a and 220 e , or 2V THN . Then, V B =V DD 2V THN =1.6V and FET 220 d has a gate to drain voltage of V GD =5.5V−1.6V=3.9V. Similarly, for FET 220 a , the gate to pad voltage V GS =5.5V−3V=2.5V and the gate to node 6 voltage V GD =1V THN . Therefore, the advantage of these circuits 20 , 30 , 40 is that no voltage restoring circuit is needed, and therefore, possible conflict between a restoring circuit and a pull-down resistor is eliminated. When the potential at the input pad 200 swings to a high voltage, the gate terminal of transistor 220 d will be sufficiently high to prevent the transistor 220 d from being ON when transistor 220 b is ON. For example, if transistors 220 e and 220 d were removed and the source terminal of transistor 220 c was tied to V DD , if the input pad 200 is HIGH, transistor 220 c would not be completely OFF, while transistor 220 b would be ON. This occurs as a result of a self-biasing of transistor 220 c . In other words, changes in the biasing of FET 220 b cause the drain current of FET 220 c to increase or decrease accordingly since this produces corresponding increases or decreases in the gate-to-source voltage of FET 220 c which may prevent FET 220 c from being completely OFF. For a typical circuit this could result in a 200-500 μA leakage, or “crow bar,” current associated with each input. Thus, for a low power application, such as in a portable computer, for a chip with about 450 inputs such leakage would be unacceptable. Hence, with transistors 220 d and 220 e in place, as shown, this leakage, or “crow bar,” current is prevented. EXAMPLE 2 0.25 micron process For a 0.25 micron process, the maximum voltage V MAX between the gate to source/drain terminals is about 3.2V. In this example, voltage V DD is defined to be 2.3V and pad voltage, V PAD is defined to be 3.6V. As described above, the voltage on node 6 will range from 0V to V DD −1V THN . Therefore, the voltage on node 6 can be characterized as V A =V DD 1V THN =2.3V−0.6V=1.7V. The voltage at node 7 will swing from V DD to V DD −2V THN . Therefore, the voltage at node 7 can be characterized as V B =V DD −2V THN =2.3V−1.2V=1.1V. In this example, for FET 220 d , the gate to source voltage V GS =3.6V−2.3V=1.3V, and the gate to drain voltage V GD =3.6V−1.1V=2.5V. That is, when the pad input voltage is HIGH, FETs 220 c and 220 d are switched OFF. Therefore, the voltage at node 7 is measured across FETs 220 a and 220 e , or 2V THN . Then, V B =V DD −2V=1.1V, and FET 220 d has a gate to drain voltage of V GD =3.6V−1.1V=2.5V. Similarly, for FET 220 a , the gate to pad voltage V GS =3.6V−2.3V=1.3V, and the gate to node 6 voltage V GD =1V THN . Therefore, the advantage of these circuits 20 , 30 , 40 is that no voltage restoring circuit is needed, and therefore, possible conflict between a restoring circuit and a pull-down resistor is eliminated. Similar to the example directed to the 0.35 micron process, no leakage, or “crow-bar,” current will occur in this example, and the speed through the circuit will be faster than prior art circuits since the propagation times from high-to-low and from low-to-high are nearly equal. It should be noted in each of these examples, that since current can flow in the subthreshold condition, if a voltage higher than the voltage on the gate terminal of transistor 220 a is placed on the PAD 200 for a long period of time, the voltage on the PADINT node 6 will approach the V DD voltage placed on the gate terminal of transistor 220 a. In this disclosure, there is shown and described a preferred embodiment of the invention, but, as also mentioned, it is to be understood that the invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein.
An apparatus including an overvoltage protection circuit is provided that comprises an input terminal configured to convey an input voltage, an output terminal configured to convey an output voltage, a buffer circuit, coupled between the input terminal and the output terminal, configured to receive and buffer the input voltage and in accordance therewith provide the output voltage, and a voltage sensing circuit, coupled to the input terminal and the buffer circuit, configured to sense the input voltage and in accordance therewith maintain the buffer circuit in a predetermined voltage range.
Briefly describe the main invention outlined in the provided context.
[ "TECHNICAL FIELD This invention relates to input circuitry, and more specifically, to a fast input buffer circuit which protects deep sub-micron complementary metal-oxide semiconductor (CMOS) transistors from overvoltage stress.", "BACKGROUND OF THE RELATED ART Input circuits have been incorporated into chip technologies for many years to provide fast input buffers which protect deep sub-micron CMOS transistors from overvoltage stress.", "Three such prior art input buffer circuits are shown in FIGS. 1A-C.", "The circuit 1 in FIG. 1A has two field effect transistors (FETs) 100 a , 100 b .", "Field effect transistor 100 a is an n-type field effect transistor, whereas FET 100 b is a p-type field effect transistor.", "An input pad 110 is connected to the drain terminal of FET 100 a .", "The gate terminal of FET 100 a is connected to voltage source V DD .", "The source terminal of FET 100 a is connected to a voltage restoring circuit 120 , in the form of FET 100 b having its gate and source terminals coupled through an inverter 130 .", "The drain terminal of FET 100 b is connected to a power supply V DD .", "Further, two inverters 130 are connected in series and coupled to the source terminal of FET 100 b. A problem with the input circuit of FIG. 1A is that the voltage restoring circuit 120 conflicts with external pull-down resistors (not shown), which slow the speed and effectiveness of the circuit.", "The voltage restoring circuit 120 “pulls-up”", "the voltage to a “strong”", "HIGH logic level when FET 100 b is switched ON.", "The large impedance of the external resistors (not shown) oppose the effectiveness of the voltage restoring circuit 120 to produce this “strong”", "HIGH logic level.", "Another prior art input circuit is shown in FIG. 1 B. The circuit 2 of FIG. 1B is composed of an input pad 110 connected to the drain terminal of FET 100 a .", "The gate terminal of FET 100 a is connected to a voltage source V DD .", "The source terminal of FET 100 a is connected to series connected inverters 130 a , 130 b , and output Y is generated.", "This transistor 100 a plays an important role in the operations of the circuit 2 of FIG. 1 B. For example, if the transistor 100 a was not included, then when the input pad 110 is powered up, e.g. to five volts, the gate-to-source voltage on the n-type FET (not shown) of the inverter 130 a will be five volts and such n-type FET would pull the output of the inverter 130 a to ground.", "This would cause the p-type FET (not shown) of the inverter 130 a to have a gate-to-drain voltage of five volts.", "For deep submicron architecture neither of these results would be acceptable.", "With the inclusion of FET 100 a , however, the voltage at node A will never rise above the voltage on the gate terminal of FET 100 a less its threshold drop (for DC conditions and long settling times, the threshold may be large).", "Therefore, the voltage at node A will be less than the internal voltage V DD .", "Hence, the voltages across transistor 100 a and the n-type and p-type FETs (not shown) of the inverter 130 a are maintained in a range to achieve reasonable long-term reliability.", "The circuit 2 of FIG. 1B does not have the conflict disadvantage characteristic of circuit 1 of FIG. 1A, however, it has the disadvantage of leaking DC current because the p-channel device (not shown) in inverter 130 a is never completely turned off.", "A third prior art input circuit is shown in FIG. 1 C. The circuit 3 of FIG. 1C is composed of a pad input 110 connected to the drain terminal of FET 100 a .", "The gate terminal of FET 100 a is connected to a voltage source V DD .", "The source terminal of FET 100 a is connected to a CMOS inverter 140 .", "This CMOS inverter 140 is composed of an n-type FET 100 c and a p-type FET 100 d. The drain terminal of FET 100 d is connected to a diode 120 a , which is a p-type FET 100 e , having its gate and source terminals coupled together.", "The drain of FET 100 e is connected to a voltage source V DD .", "The output of the CMOS inverter 140 is connected to voltage restoring circuit 120 , which is FET 100 b having its gate and source terminals coupled through an inverter 130 .", "The drain of FET 100 b is connected to a voltage source V DD .", "Further, another inverter 130 is coupled to the source terminal of FET 100 b. Although the circuit 3 in FIG. 1C avoids the disadvantages of the circuits shown in FIGS. 1A and 1B, the circuit 3 of FIG. 1C is slow.", "Furthermore, it also has a natural magnitude hysteresis.", "This hysteresis will slow down the AC performance, but for any input, the output results will consistently be the same.", "Furthermore, to ensure threshold voltages and reasonable speeds, the sizes of p-type FETs 100 d and 100 e must be made large.", "The reason for the dimensional differences between the n-type and p-type FETs stems from the characteristic differences between the devices.", "The relationship between PMOS and NMOS transistors is such that for devices having the same dimensions, the current in a PMOS transistor is less than half of that in an NMOS device and the ON resistance of a p-channel MOSFET is nearly three times that for an n-channel MOSFET.", "Both circuits 1 and 3 represented in FIGS. 1A and 1C inherently have a large amount of hysteresis (one-ended hysteresis).", "To meet the 0.8 volt “low”", "and two volt “high”", "thresholds (for 3.3 volt systems), the propagation times from low-to-high and from high-to-low will have a large amount of skew between them.", "Alternatively, to achieve the same values of current and ON resistance as in an NMOS transistor, the channel width/length ratio must be increased to account for the lower hole mobility.", "This results in PMOS devices requiring nearly three times the area of an equivalent NMOS device.", "It is thus desirable to provide a fast input buffer which protects deep sub-micron CMOS transistors from overvoltage stress with minimal DC power requirements.", "Furthermore, it is desirable to provide a fast input buffer which protects deep sub-micron CMOS transistors from overvoltage stress which has no unusual bus loading and is faster than current I/O circuitry.", "It is also desirable to provide a fast input buffer which protects deep sub-micron CMOS transistors from overvoltage stress which meets transistor-transistor logic (TTL) thresholds and has symmetrical response times for fast propagation times from LOW logic level to HIGH logic level (T PLH ) and from HIGH logic level to LOW logic level (T PHL ).", "SUMMARY OF THE INVENTION An apparatus including an overvoltage protection circuit is provided that comprises an input terminal configured to convey an input voltage, an output terminal configured to convey an output voltage, a buffer circuit, coupled between the input terminal and the output terminal, configured to receive and buffer the input voltage and in accordance therewith provide the output voltage, and a voltage sensing circuit, coupled to the input terminal and the buffer circuit, configured to sense the input voltage and in accordance therewith maintain the buffer circuit in a predetermined voltage range.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a conventional input circuit.", "FIG. 1B is another conventional input circuit.", "FIG. 1C is yet another conventional input circuit.", "FIG. 2 is an input circuit in accordance with one embodiment of the present invention.", "FIG. 3 is an input circuit in accordance with another embodiment of the present invention.", "FIG. 4 is an input circuit in accordance with yet another embodiment of the present invention.", "FIG. 5 is an input circuit in accordance with still another embodiment of the present invention.", "FIG. 6A is an input circuit in accordance with yet still another embodiment of the present invention.", "FIG. 6B is a timing diagram of the input circuit of FIG. 6A illustrating the effect of hysteresis on the circuit.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The input circuit 20 of the present invention will now be explained with reference to FIGS. 2-4.", "FIG. 2 shows an input circuit 20 in accordance with one embodiment of the present invention.", "An input pad 200 is connected to the anode of diode 210 a .", "The cathode of diode 210 a is connected to a voltage source V DDESD .", "Another diode 210 b has its cathode connected to input pad 200 .", "The anode of diode 210 b is connected to a voltage source V SSIO .", "Briefly, these diodes 210 a , 210 b serve to protect the circuit 20 from high voltage “spikes,” by discharging the extremely high voltage to the “ESD”", "and “IO”", "protection circuits (not shown).", "Therefore, the circuit 20 will not be damaged by these extremely high voltage “spikes.”", "In the circuit 20 , node 5 will have a full voltage range from V DD to 0V.", "The voltage on node 6 will range between 0V to V DD −1V THN .", "That is, when the input from the pad 200 is HIGH, the source potential of FET 220 a will be larger than the gate potential, i.e. V GS <V T , causing the transistor 220 a to be OFF (the voltage at node 6 will therefore be V DD −1V THN ).", "However, when the pad 200 input is LOW, the source terminal of FET 220 a will be at a lower potential than the gate terminal, i.e. V GS >V T , and FET 220 a will be ON, thus, the voltage at node 6 will be 0V.", "Therefore, as explained above, when the pad 200 input is HIGH, the voltage at node 6 will be HIGH, switching ON transistors 220 b and 220 e .", "Therefore, the voltage at node 5 will be 0V and the voltage at node 7 will be charged to V DD −2V THN .", "When the pad 200 input is LOW, the voltage at node 6 will be LOW and transistor 220 c will be switched ON.", "Furthermore, since the input is LOW, transistor 220 d will be switched ON.", "Thus, the voltage at node 5 will swing to V DD .", "The voltage at node 7 will swing to V DD .", "Therefore, FET 220 a prevents overvoltage on the gate to source terminal voltage of FET 220 b by ensuring the largest voltage swing at node 6 will be no greater than V DD −1V THN .", "Furthermore, as described above node 7 is charged up when the pad input 200 is HIGH.", "Therefore, an overvoltage problem across the gate to drain terminal voltage of FET 220 d is avoided.", "The overvoltage protection circuit is thus provided with an internal overvoltage protection.", "In other words, not only is the buffer circuit protected from overvoltage stress, but the voltage sensing circuit is configured in a way to protect itself from overvoltage stress.", "Thus, this circuit solves the overvoltage problem inherent in many input circuits and performs faster than conventional overvoltage protection circuits.", "For example, referring again to FIGS. 1A and 1C, such conventional circuits inherently have a lot of hysteresis (one-ended hysteresis).", "As an example, for 3.3V systems, the 0.8V LOW and 2V HIGH voltage magnitudes indicate the voltage magnitudes at which these circuits will interpret a state change.", "For example, an input voltage between the ranges of 0.8V and 2V would be interpreted to be that of the previous state.", "However, any input voltage below 0.8V will be interpreted as a strong logic LOW.", "Likewise, any input voltage above 2V will be interpreted as a strong logic HIGH.", "Thus, the propagation times from low-to-high and from high-to-low will have a large amount of skew between them due to this “hysteresis window”", "(low-to-high of approximately 0.9 ns and high-to-low of approximately 4.5 ns).", "Optimal timing would be with near similar propagation times from low-to-high and from high-to-low.", "As a result of the addition of the voltage sensing circuit component to the circuit of FIG. 2, similar propagation times from low-to-high and from high-to-low, that are partially a function of slow ramp time, can be achieved.", "Moreover, these times are generally of about half the propagation times from low-to-high and from high-to-low, respectively, of conventional overvoltage circuits.", "Thus, the circuit of FIG. 2 solves the overvoltage problem inherent in many input circuits and performs faster than conventional overvoltage protection circuits.", "FIG. 3 shows a second embodiment of the input circuit 30 of the present invention with a sleep mode.", "The sleep mode provides a method of controlling the output of the circuit irrespective of the input.", "An example of how this is accomplished will be explained later.", "The differences in circuit structure between the circuits of FIGS. 2 and 3 will now be explained with like components referenced by like reference numbers.", "Circuit 30 of FIG. 3 is similar to circuit 20 of FIG. 2 except for the addition of two FETs 220 f and 220 g .", "FET 220 f is an n-type field effect transistor, whereas FET 220 g is a p-type field effect transistor.", "FET 220 f has its drain terminal connected, in series, to the drain terminal of FET 220 c .", "The source terminal of FET 220 f is connected to the drain terminal of FET 220 b .", "The gate terminal of FET 220 f is connected to the sleep control signal SLEEP_Z.", "FET 220 g has its drain terminal connected to the drain terminals of FETs 220 c and 220 f .", "The source terminal of FET 220 g is connected to a voltage source V DD .", "The gate terminal of FET 220 g is connected to the sleep control signal SLEEP_Z.", "Operation of the circuit 30 of FIG. 3 is such that the output Y can only be HIGH, i.e. logic level “1,” when both pad input 200 is HIGH and SLEEP_Z is HIGH.", "That is, the input circuit 30 is controlled by SLEEP_Z.", "For example, if SLEEP_Z is HIGH and pad input 200 is LOW, output Y will be LOW.", "If SLEEP_Z is HIGH and pad input 200 is HIGH, output Y will be HIGH.", "If SLEEP_Z is LOW, then regardless of the logic level of pad input 200 , output Y will always be LOW.", "FIG. 4 is another embodiment 40 of the input circuit 40 of the present invention with overvoltage protection, sleep mode and hysteresis.", "The differences in circuit structure between the circuits of FIGS. 2, 3 and 4 will be explained with reference to like components indicated by like reference numbers.", "Circuit 40 is similar to the circuit 30 of FIG. 3 except for the addition of two FETs 220 h and 220 i .", "FET 220 h is an n-type field effect transistor, whereas FET 220 i is a p-type field effect transistor.", "FET 220 h has its source terminal connected to the connection of the source terminal of FET 220 f and the drain terminal of FET 220 b .", "The drain terminal of FET 220 h is connected to a voltage source V DD .", "The gate terminals of FETs 220 h and 220 i are connected to node 5 .", "The source terminal of FET 220 i is connected to a voltage source V SS .", "The drain terminal of FET 220 i is connected to the common node of the source terminals of FETs 220 c and 220 e and the drain terminal of FET 220 d (node 7 ).", "Thus, operation of the circuit of FIG. 4 is as that of the circuit of FIGS. 2 and 3, with the addition of noise tolerance.", "That is, the hysteresis elements, i.e. FETs 220 h and 220 i provide a noise tolerance to the circuit.", "Typically, the input from the pad 200 will not have “clean”", "rise and fall times.", "Instead, these signals will have a “jitter”", "effect, which is interpreted as noise.", "In this circuit, the hysteresis window is approximately 500 mV.", "Thus, the circuit will interpret an input voltage between the ranges of 1.1V to 1.6V to be that of the previous state.", "However, any input voltage below 1.1V will be interpreted as a strong logic LOW.", "Likewise, any input voltage above 1.6V will be interpreted as a strong logic HIGH.", "It should be noted that these voltage thresholds are merely an example of one embodiment.", "It is possible to alter both the amount of hysteresis and the absolute high and low thresholds.", "For example, by resizing transistors 220 d , 220 c , 220 f , 220 b , 220 i and 220 h , the amount of hysteresis can be changed, as well as the actual trip points for a high or low threshold.", "Referring again to FIG. 4, depending upon the potential at the output of the inverter (node 5 ), that potential may be either “high”", "enough to turn FET 220 h ON, or “low”", "enough to turn FET 220 i ON.", "Since the drain terminal of FET 220 h is connected to V DD , if the output potential is “high”", "enough to raise the gate-to-source voltage of FET 220 h above the threshold voltage, then FET 220 h will turn ON and effectively pull node 5 HIGH very quickly due to V DD being effectively applied to node 5 via FET 220 f and FET 220 h. In contrast, since the source terminal of FET 220 i is connected to V SS , if the output potential is “low”", "enough to drop the gate-to-source voltage of FET 220 i below the threshold voltage, then FET 220 i will turn ON and effectively pull node 5 LOW very quickly due to V SS being effectively applied to node 5 via FET 220 c and FET 220 i. Thus, a tolerance is introduced in an effort to compensate for noise jitter in the input voltage to produce a desired output logic level.", "Whereas the hysteresis circuit components, i.e., FET 220 h and FET 220 i , of FIG. 4 indirectly affect node 5 through FETs 220 f and 220 c , respectively, it is possible for the hysteresis circuit components to directly affect node 5 , such as is shown in FIG. 5 .", "Referring now to FIG. 5, in an alternative embodiment shown therein circuit 50 is similar to the circuit 30 of FIG. 3 except for the addition of FET 220 j and inverter 230 .", "The source terminal of FET 220 j is connected to a voltage source V DD .", "The drain terminal of FET 220 j is connected to node 5 .", "An inverter 230 is coupled between the gate terminal of FET 220 j and node 5 .", "Thus, hysteresis will affect the circuit 50 , much like described above with respect to the circuit 1 shown in FIG. 1 A. However, in the circuit 50 shown in FIG. 5, the hysteresis circuit components, i.e., FET 220 j and inverter 230 , directly affect node 5 as opposed to the indirect effect on node 5 that occurs in FIG. 4 .", "Perhaps the hysteresis effect can be best illustrated by FIGS. 6A and 6B.", "FIG. 6A illustrates an input circuit according to another embodiment of the invention.", "Specifically, the circuit 60 shown in FIG. 6A is almost identical to the circuit 40 of FIG. 4, except that FET 220 e is absent from the circuit 60 of FIG. 6A, merely for simplification purposes.", "FIG. 6B is a graphical representation of certain of the node voltages in FIG. 6 A. The three node voltages of interest are V(PAD) (the pad input voltage) 200 , output V(Y) 11 , and V(YBAR) (represented by node 5 in the Figure).", "The voltage plot represented in FIG. 6B is a voltage vs.", "time plot of a simulation of the circuit shown in FIG. 6 A. The voltage axis ranges from 0V to 3V and the time axis ranges from 0 s to 4 μs.", "Input signal V(PAD) is defined for the particular circuit, and will occur as defined, since it is represented as a perfect voltage source during simulation of the circuit of FIG. 6 A. V(PAD) is thus purposely described as a slow ramp, 20 μs rise time and 20 μs fall time, in order to view the actual hysteresis of the circuit.", "For the particular simulation of the circuit of FIG. 6A, the amount of hysteresis would be 0.53V (1.64V−1.1V=0.53V, measured by the state change voltage potentials) of hysteresis.", "Hysteresis usually does not affect the output voltage V(Y) maximum/minimum swing, but it does affect the input voltage required to trigger an output voltage transition.", "Therefore, the simulated peak rise time and fall time of the input voltage V(PAD) 200 are nearly identical, peaking at about 20 μs.", "However, as mentioned above, hysteresis can affect the simulated peak rise and fall times.", "As can be seen by reference number 201 (V(YBAR)), hysteresis affects both the maximum amplitude voltage V(PAD) 200 and the peak rise time (shown by the dotted line 8 ).", "For example, without hysteresis effects, the simulated peak rise and fall times are nearly identical, approximately 20 μs.", "With the inclusion of hysteresis effects, as represented by dotted line 201 , signal V(PADINT) 8 will equal V(PAD) 200 until V(PAD) 200 rises above V DD −V TH22a , at which point V(PADINT) 8 will no longer follow V(PAD) 200 , and the simulated peak will occur at the 22 μs point, thereby making the rise time approximately 2 μs slower and the fall time approximately 2 μs faster.", "However, hysteresis will not affect the points at which the circuit output will effectively change states.", "As described above, the circuit will interpret an input voltage between the ranges of 1.1V to 1.6V to be that of the previous state.", "However, any input voltage below 1.1V will be interpreted as a strong logic LOW.", "Likewise, any input voltage above 1.6V will be interpreted as a strong logic HIGH.", "These voltage ranges are indicated in the plot of FIG. 6B as the intersection points 9 A and 9 B. Thus, a tolerance is introduced in an effort to compensate for noise jitter in the input voltage to produce a desired output logic level.", "Although the above circuit has been described utilizing a connection of field effect transistors, similar results can be obtained by substituting bipolar junction transistors for the respective field effect transistors.", "The following examples, recited with reference to the circuit 20 shown in FIG. 2, will better illustrate the benefits and advantages of the fast overvoltage protected input circuit of the present invention.", "These examples are for illustrative purposes only and in no way are intended to be seen as limiting the invention to their description.", "EXAMPLE 1 0.35 micron process For a 0.35 micron process the maximum voltage V MAX between the gate to drain/source terminals is 4.2V.", "In this example, V DD is defined to be 3V and V PAD is defined to be 5.5V.", "As described above, the voltage on node 6 will range from 0V to V DD −1V THN .", "Therefore, the voltage on node 6 can be characterized as V A =V DD −1V THN =3V−0.7V=2.3V.", "The voltage at node 7 will swing from V DD to V DD −2V THN .", "Therefore, the voltage at node 7 can be characterized as V B =V DD −2V THN =3V−1.4V=1.6V.", "Thus, in this example, for FET 220 d , the gate to source voltage V GS =5.5V−3V=2.5V, and the gate to drain voltage V GD =5.5V−1.6V=3.9V.", "Thus, when the pad input voltage is HIGH, FET 220 d will be switched OFF.", "The source potential of FET 220 a will be large compared to the gate potential.", "Therefore, the voltage at node 7 is measured across FETs 220 a and 220 e , or 2V THN .", "Then, V B =V DD 2V THN =1.6V and FET 220 d has a gate to drain voltage of V GD =5.5V−1.6V=3.9V.", "Similarly, for FET 220 a , the gate to pad voltage V GS =5.5V−3V=2.5V and the gate to node 6 voltage V GD =1V THN .", "Therefore, the advantage of these circuits 20 , 30 , 40 is that no voltage restoring circuit is needed, and therefore, possible conflict between a restoring circuit and a pull-down resistor is eliminated.", "When the potential at the input pad 200 swings to a high voltage, the gate terminal of transistor 220 d will be sufficiently high to prevent the transistor 220 d from being ON when transistor 220 b is ON.", "For example, if transistors 220 e and 220 d were removed and the source terminal of transistor 220 c was tied to V DD , if the input pad 200 is HIGH, transistor 220 c would not be completely OFF, while transistor 220 b would be ON.", "This occurs as a result of a self-biasing of transistor 220 c .", "In other words, changes in the biasing of FET 220 b cause the drain current of FET 220 c to increase or decrease accordingly since this produces corresponding increases or decreases in the gate-to-source voltage of FET 220 c which may prevent FET 220 c from being completely OFF.", "For a typical circuit this could result in a 200-500 μA leakage, or “crow bar,” current associated with each input.", "Thus, for a low power application, such as in a portable computer, for a chip with about 450 inputs such leakage would be unacceptable.", "Hence, with transistors 220 d and 220 e in place, as shown, this leakage, or “crow bar,” current is prevented.", "EXAMPLE 2 0.25 micron process For a 0.25 micron process, the maximum voltage V MAX between the gate to source/drain terminals is about 3.2V.", "In this example, voltage V DD is defined to be 2.3V and pad voltage, V PAD is defined to be 3.6V.", "As described above, the voltage on node 6 will range from 0V to V DD −1V THN .", "Therefore, the voltage on node 6 can be characterized as V A =V DD 1V THN =2.3V−0.6V=1.7V.", "The voltage at node 7 will swing from V DD to V DD −2V THN .", "Therefore, the voltage at node 7 can be characterized as V B =V DD −2V THN =2.3V−1.2V=1.1V.", "In this example, for FET 220 d , the gate to source voltage V GS =3.6V−2.3V=1.3V, and the gate to drain voltage V GD =3.6V−1.1V=2.5V.", "That is, when the pad input voltage is HIGH, FETs 220 c and 220 d are switched OFF.", "Therefore, the voltage at node 7 is measured across FETs 220 a and 220 e , or 2V THN .", "Then, V B =V DD −2V=1.1V, and FET 220 d has a gate to drain voltage of V GD =3.6V−1.1V=2.5V.", "Similarly, for FET 220 a , the gate to pad voltage V GS =3.6V−2.3V=1.3V, and the gate to node 6 voltage V GD =1V THN .", "Therefore, the advantage of these circuits 20 , 30 , 40 is that no voltage restoring circuit is needed, and therefore, possible conflict between a restoring circuit and a pull-down resistor is eliminated.", "Similar to the example directed to the 0.35 micron process, no leakage, or “crow-bar,” current will occur in this example, and the speed through the circuit will be faster than prior art circuits since the propagation times from high-to-low and from low-to-high are nearly equal.", "It should be noted in each of these examples, that since current can flow in the subthreshold condition, if a voltage higher than the voltage on the gate terminal of transistor 220 a is placed on the PAD 200 for a long period of time, the voltage on the PADINT node 6 will approach the V DD voltage placed on the gate terminal of transistor 220 a. In this disclosure, there is shown and described a preferred embodiment of the invention, but, as also mentioned, it is to be understood that the invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein." ]
RELATED APPLICATION [0001] This application is a divisional of U.S. application Ser. No. 10/655,397, filed on Sep. 5, 2003, the disclosure of which is hereby incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a motion picture encoding device and a motion picture decoding device, which have an inter-field prediction mode. [0004] 2. Description of the Related Art [0005] Generally, motion picture data is large in size. Therefore, when motion picture data is transmitted from a transmitting device to a receiving device or when it is stored in a storage device, highly efficient encoding is applied to motion picture data. In this case, “highly efficient encoding” is an encoding process of converting a specific data string into another data string, and compressing the amount of data. [0006] There are two types of motion picture data: one is mainly composed of only frames and the other is composed of fields. A prior art for compressing a field image is mainly described below. [0007] As the highly efficient encoding method of motion picture data, a frame/field prediction encoding is known. [0008] FIG. 1 shows a block diagram of the configuration of the frame/field predictive encoding device. [0009] This encoding method utilizes the fact that a plurality of segments of motion picture data has high correlation in a time direction with each other. The operation shown in FIG. 1 is roughly described below. A subtracter 39 generates a differential image between an inputted original image and a predicted image, and an orthogonal transform unit 31 , a quantization unit 32 and a coefficient entropy encoding unit 40 encode the differential image. An inverse quantization unit 33 and an inverse orthogonal transform unit 34 reproduce the differential image from the output of the quantization unit 32 . Then, a decoded image generation unit 35 decodes the encoded image using the reproduced differential image reproduced by the decoded image generation unit 35 and the predicted image used at the time of encoding. A decoded image storage unit 36 stores the reproduced image. Then, motion vector calculation unit 37 calculates a motion vector between the reproduced image and a subsequent input image, and a predicted image generation unit 38 generates a predicted image using the motion vector The generated motion vector is encoded by a vector entropy encoding unit 41 and is outputted through a MUX 42 together with the encoded coefficient data encoded by the coefficient entropy encoding unit 40 . In other words, since in motion picture data, there is generally high similarity between frame/field data at a specific time and frame/field data at a subsequent time, the inter-frame/field predictive encoding method utilizes such a property. For example, in a data transmission system adopting the inter-frame/field predictive encoding method, a transmitting device generates motion vector data indicating displacement from previous frame/field image to a target frame/field image, and differential data between a predicted image in the target frame/field which is generated from the previous frame/field image using its motion vector data and a real image in the target frame/field, and transmits the motion vector data and the differential data to a receiving device. The receiving device reproduces the image in the target frame/field from the received motion vector data and differential data. [0010] So far, the summary of the frame/field predictive encoding has been described with reference to FIG. 1 . Next, frame predictive encoding and field predictive encoding are described below [0011] FIGS. 2 and 3 show a format used to encode a field image that is commonly used in ISO/IEC MPEG-2/MPEG-4 (hereinafter called “MPEG-2” and “MPEG-4”, respectively) and the final committee draft of ITU-T H.264/ISO/IEC MPEG-4 Part 10 (Advanced video coding (AVC))(“Joint Final Committee Draft (JFCD) of Joint Video Specification(ITU-T REC, H.264|ISO/IEC 14496-10 AVC)”, JVT-D157, or ISO/IEC JTC1/SO29/WG11 MPEG02/N492, July 2002, Klagenfurt, AT)(hereinafter called “AVC FCD”), which ITU-T and ISO/IEC jointly were standardizing as of August 2002. Specifically, each frame is composed of two fields: a top field and a bottom field. FIG. 2 shows the respective positions of a luminance pixels and a chrominance pixels, and a field to which each pixel belongs. As shown in FIG. 2 , odd number-ordered luminance lines, such as a first luminance line ( 50 a ), a third luminance line ( 50 b ), a fifth luminance line ( 50 c ), a seventh luminance line ( 50 d ), etc., belong to the top field, and even number-ordered lines, such as a second luminance line ( 51 a ), a fourth luminance line ( 51 b ), a sixth luminance line ( 51 c ), a eighth luminance line ( 51 d ), etc., belong to the bottom field. Similarly, odd number-ordered chrominance lines, such as a first chrominance line ( 52 a ), a third chrominance line ( 52 b ), etc., belong to the top field, and even number-ordered chrominance line, such as a second chrominance ( 53 a ), a fourth chrominance line, etc., belong to the bottom field. [0012] Each of the top and bottom fields indicates an image at a different time. Next, the time/spatial disposition of the top and bottom fields is described with reference to FIG. 3 . [0013] In FIGS. 3 and after, the technology of the present invention relates to the vertical component of a motion vector. Therefore, in this specification, horizontal pixel components are not shown, and all the horizontal components of the motion vector are assumed to be 0 for convenience sake. However, in order to show conventional problems and the effects of the present invention, the positional relation between luminance and chrominance in each field is accurately shown. [0014] In FIG. 3 , the vertical and horizontal axes represent the pixel position of a vertical component in each field and the elapse of time, respectively. Since there is no positional change in a field of the horizontal component of each image, in FIG. 3 , its horizontal pixel component is not shown nor is described. [0015] As shown in FIG. 3 , the pixel position of a chrominance component deviates from the pixel position in a field of a luminance component by a quarter vertical pixel. This is because relationship of pixel positions as shown in FIG. 2 is achieved when a frame is constructed from both Top and Bottom fields. If it is based on a NTSC format, each time interval between adjacent top and bottom fields ( 64 a : 65 a , 65 a : 64 b , etc.) is approximately 1/60 seconds. Each time interval between two consecutive top fields ( 64 a : 64 b , etc.) or between two consecutive bottom field ( 65 a : 65 b , etc.) are approximately 1/30 seconds. [0016] Next, the frame predictive encoding mode of a field image and its field prediction, which is adopted in MPEG-2 and AVC FCD, are described. [0017] FIG. 4 shows a method for constructing a frame using two consecutive fields (adjacent top and bottom fields) in a frame predictive mode. [0018] As shown in FIG. 4 , a frame is reconstructed by two time-consecutive fields (top and bottom fields). [0019] FIG. 5 shows a frame predictive mode. [0020] In FIG. 5 it is assumed that each frame, such as 84 a , 84 b , 84 c , etc., is already reconstructed by two consecutive fields (top and bottom fields), as shown in FIG. 4 . In this frame predictive mode, a frame to be encoded which is composed of top and bottom fields is encoded. As a reference image, one reference frame is constructed by two consecutive fields (top and bottom fields) stored for reference use, and is used to predict the target frame to be encoded. Then, these two frame images are encoded according to the process flow shown in FIG. 1 . In the expression method of a motion vector of this frame predictive encoding mode, a zero vector, that is, ( 0 , 0 ) indicates a pixel located in the same spatial position. Specifically, the motion vector ( 0 , 0 ) of a luminance pixel 82 that belongs to frame# 2 ( 84 b ) indicates the pixel position 81 of frame# 1 ( 84 a ). [0021] Next, a field predictive encoding mode is described. [0022] FIG. 6 shows a predictive method in an inter-field predictive mode. [0023] In a field predictive mode, an encoding target is one top field ( 94 a , 94 b , etc.) or bottom field ( 95 a , 95 b , etc.) that is inputted as an original image. As a reference image, a top field or bottom field that is stored before can be used. In this case, it is generally defined that the fact that an original image field parity and a reference field parity are the same means that the original image field and the reference field both are top fields or bottom fields. For example, in a prediction 90 between fields with the same parity shown in FIG. 6 , an original image field ( 94 b ) and a reference field ( 94 a ) both are top fields. Similarly, it is generally defined that the fact that an original image field parity and a reference field parity are different means that one of original image and reference fields is a top field and the other is a bottom field. For example, in a prediction 91 between different parity fields shown in FIG. 6 , the original image field is a bottom field ( 95 a ) and the reference field is a top field ( 94 a ). Then, these original image and reference fields are encoded according to the process flow shown in FIG. 1 . [0024] In the prior art, in both frame and field modes, a motion vector is calculated based on a pixel position in each frame/field. Here, a conventional motion vector calculation method and a conventional pixel corresponding method used when a motion vector is given are described. [0025] FIG. 7 defines the coordinates of a frame/field image widely used in MPEG-2 coding, MPEG-1 coding, AVC FCD coding, etc. White circles in FIG. 7 are pixel definition positions in target frames/fields. In the coordinates of this frame/field image, the upper left corner is designated as the origin ( 0 , 0 ), and values 1, 2, 3, etc., are sequentially assigned to both horizontal and vertical pixel definition positions. Specifically, the coordinates of a pixel that are located at the n-th horizontal position and the m-th vertical position are (n,m). Similarly, the coordinates of a position interpolated among the pixels are also defined. Specifically, since a position 180 marked with a black circle in FIG. 7 is located at 1.5 pixels in the horizontal direction from the pixel located in the upper left corner and at 2 pixels in the vertical direction, the coordinates of the position 180 is expressed as (1.5, 2). In a field image, there are only a half of the pixels of a frame image in the vertical direction. However, even in this case, the coordinates of a pixel are defined in the same way as in FIG. 7 , based on pixel positions located in each field. [0026] Next, the definition of a motion vector between fields is described using the coordinate system shown in FIG. 7 . [0027] FIG. 8 shows a conventional calculation method of a motion vector between corresponding pixels between fields. The definition of a motion vector requires the position of a coding field and the position of a reference field. A motion vector is defined between these two points. Thus, a motion vector between a coding field coordinates 201 (X s ,Y s ) and a reference field coordinates 202 (X d ,Y d ) is calculated. [0028] In the conventional calculation method of a motion vector between pixels corresponding to between-fields, a motion vector is calculated by the same method described below, regardless of whether the coding field or reference field is a top field or a bottom field. [0029] Specifically, coding field coordinates 201 (X s ,Y s ) and reference field coordinates 202 (X d ,Y d ) are inputted to a motion vector calculation unit 200 , and as a motion vector 203 between these two points, (X d −X s ,Y d −Y s ) is given. [0030] FIG. 9 shows a conventional method for calculating a pixel that is pointed by a motion vector defined between fields. In this case, it is assumed that a motion vector is calculated by the method shown in FIG. 8 . The calculation of reference frame/field coordinates requires a coding frame/field position and a motion vector. In the case shown in FIG. 9 , it is assumed that a motion vector 211 (X,Y) is given for coding field coordinates 212 (X s ,Y s ), and reference field coordinates can be calculated using both the motion vector 212 (X,Y) and the coding field coordinates 212 (X s ,Y s ). In the conventional calculation method of a motion vector between corresponding pixels between fields, a reference field position is calculated by the same method described below, regardless of whether the coding field or reference field is a top field or a bottom field. Specifically, a motion vector 211 (X,Y) and coding field coordinates 212 (X s ,Y s ) are inputted to a pixel corresponding unit 210 , and as reference field coordinates 213 , coordinates (X s +X,Y s +Y) is given. [0031] The definition of the relation between a vector and a pixel position applies to both a luminance component and chrominance component. In MPEG-1/MPEG-2/AVC FCD, which all are general motion picture encoding methods, only the vector of a luminance component is encoded, and the vector of a chrominance component is calculated by scaling down the luminance component. Particularly, in AVC FCD, since the number of vertical pixels and that of horizontal pixels of a chrominance component are a half of those of a luminance component, respectively, it is specified that a motion vector used to calculate the predictive pixel of a chrominance component should be obtained by accurately scaling down the motion vector of the luminance component to a half. [0032] FIG. 10 shows a conventional method for calculating a chrominance motion vector using a luminance motion vector. [0033] Specifically, if a luminance motion vector 221 and a chrominance motion vector 222 are (MV_x,MV_y) and (MVC_x, MVC_y), respectively, a chrominance motion vector generation unit 220 can calculate a chrominance motion vector 222 according to the following equation. ( MVC — x, MVC — y )=( MV — x /2 ,MV — y /2)  (1) This conventional calculation method can be used regardless of whether a motion vector is used for predicttion between fields with the same parity or between fields with different parity. [0034] In AVC FCD, as the accuracy of the motion vector of a luminance component, 1/4 pixel accuracy can be applied. Therefore, as a result of equation (1), as the accuracy of the motion vector of a chrominance component, a vector having 1/8 pixel accuracy, that is, accuracy at the decimal fraction, can be used. [0035] FIG. 11 shows the calculation method of the interpolated pixel of a chrominance component that is defined in AVC FCD. [0036] In FIG. 11 , a black circle and a white circle represent an integer pixel and an interpolated pixel, respectively. In this case, the horizontal coordinate of an interpolated pixel G( 256 ) is obtained by internally dividing each horizontal coordinate between points A( 250 ) and C( 252 ) at a ratio α:1-α, and the vertical coordinate can be obtained by internally dividing each vertical coordinate between points A( 250 ) and B( 251 ) at β:1-β. In this case, α and β are a value between 0 and 1. An interpolated pixel G( 256 ) defined by such positions can be roughly calculated as follows using integer pixels A( 250 ), B( 251 ), C( 252 ) and D( 253 ), which are located around the interpolated pixel G( 256 ), and using β and β. G =(1−α)·(1−β)· A +(1−α)·β· B +α·(1−β)· C+α·βD   (2) [0037] The interpolated pixel calculation method of a chrominance component, using the method shown in FIG. 11 is just one example, and there is no problem in using another calculation method. [0038] In the case of this field encoding mode, in a prediction in which an original image field and a reference field are different, that is, between fields with different parity, the respective zero vectors of the motion vector of a luminance component and that of a chrominance component are not parallel in the definition of AVC FCD. Specifically, if a prediction is made using the motion vector of a chrominance component calculated using the motion vector of a luminance component according to the conventional definition, a pixel located in a position spatially deviated from that of the luminance component is to be referenced. This fact is described below with reference to FIG. 12 . In FIG. 12 , it is assumed that a top field 130 , a bottom field 131 and a top field 132 continue timewise. In this case, bottom field 131 is to be encoded using top field 130 . In this inter-field encoding, the vertical motion vector in the same line of each field is defined to be zero. Therefore, if a zero vector ( 0 , 0 ) is assigned to a luminance pixel 133 a that belongs to the second line of bottom field 131 , this pixel can be predicted from a pixel 135 a in top field 130 . Similarly, when a zero vector ( 0 , 0 ) is assigned to a chrominance pixel 133 a which belongs to the first line of the bottom field 131 , this pixel is predicted from the pixel 137 a which is in the first line of chrominance of the top field 130 . Similarly, a luminance pixel 133 b in the third line and a chrominance pixel 134 b , which belong to top field 132 are predicted from pixels 135 b in the third line of luminance and 137 b in the second line of chrominance in bottom field 131 , respectively. Since essentially it is preferable that a chrominance motion vector and a luminance motion vector are parallel, chrominance pixels 134 a and 134 b should be predicted from the positions 136 a and 136 b , respectively, if a luminance motion vector is as it is. [0039] As described earlier, in a prediction between fields with different parity, the fact that the respective zero vectors of luminance and chrominance are not parallel is explained. In the case of AVC FCD, this fact causes the following problems for all vectors in a prediction between fields with different parity. FIGS. 13 and 14 show such problems. Problems in the case of AVC FCD are described below. In the explanation below, a horizontal component of a motion vector is set to zero in all cases for brevity. [0040] FIG. 13 shows a conventional problem caused if a chrominance motion vector is conventionally calculated using a luminance motion vector when a reference field and a coding field are a bottom field and a top field, respectively. In AVC FCD, since, as is clear from equation (1), it is specified that the number of vertical and horizontal pixels of a chrominance component are a half of those of a luminance component, a motion vector used to calculate the predictive pixel of a chrominance should be scaled down to a half of the motion vector of a luminance component. This is regardless of whether a motion vector is used for predicttion between frames, between fields with the same parity or between fields with different parity. [0041] It is shown below that this definition causes a problem when a chrominance motion vector is calculated using a luminance motion vector defined between fields with different parity. In FIG. 13 , a coding field top field luminance pixel 140 in the first line has (0,1) as a predictive vector, and as a result, it points a bottom reference field luminance pixel position 141 in the second line as a predictive value. [0042] In this case, a chrominance motion vector that belongs to the same block is calculated to be (0,½), according to equation (1). If a prediction is made using motion vector (0,½) as a predictive value of a coding field top field chrominance pixel 142 in the first line, a pixel position 143 is used as predicted value, which shifts downward by half a pixel from a pixel in the first line of a bottom reference field chrominance component. [0043] In this case, a luminance motion vector (0,1) and a chrominance vector (0,½) are not parallel. It is preferable to use a bottom reference field chrominance predictive pixel position 145 to which a chrominance motion vector parallel to a luminance motion vector is applied. [0044] FIGS. 14 shows a conventional problem caused if a chrominance motion vector is calculated using a luminance motion vector when a reference field and a coding field are a top field and a bottom field, respectively. As described in FIG. 13 , in FIG. 14 , a bottom coding field luminance pixel 150 in the first line has (0,1) as a predictive vector, and as a result, it points a reference top field luminance pixel position 151 in the second line as a predictive value. [0045] In this case, a chrominance motion vector that belongs to the same block is calculated to be (0,½), according to equation (1). If a prediction is made using motion vector (0,½) as a predictive value of a bottom coding field chrominance pixel 152 , a pixel position 153 is used as predicted value which is shifted by half a pixel from a top reference field chrominance pixel position 153 in the first line. [0046] In this case, a luminance motion vector (0,1) and a chrominance vector (0,½) are not parallel. It is preferable to use a top reference field chrominance predictive pixel position 155 to which a chrominance motion vector parallel to a luminance motion vector is applied. [0047] As described above, if a reference field parity and a coding field parity are different, according to the conventional predictive method, a pixel located in the position of a luminance component spatially deviated from that of the chrominance component is to be referenced, and a predictive image, in which a pixel located in the position of a luminance component is spatially deviated from that of the chrominance component, is generated not only for a zero vector but for all the vectors. Note that, in the above explanation, vector are said to be parallel or not parallel by considering the case where the direction in time of a luminance motion vector and a chrominance motion vector, that is, time direction from coding field to reference field in included in a motion vector. The same is true below. SUMMARY OF THE INVENTION [0048] It is an object of the present invention to provide a motion picture encoding device and a motion picture decoding device capable of particularly improving predictive efficiency of a chrominance component and improving encoding efficiency accordingly, in encoding between different field images. [0049] The motion picture encoding device of the present invention for making the inter-Field motion compensation of a motion picture signal composed of a plurality of fields comprises a plurality of chrominance motion vector generation units generating a chrominance motion vector using a luminance motion vector in a motion picture encoding device; and a selection unit selecting one of the chrominance motion vector generation units used to generate a chrominance vector, using the reference field parity and coding field parity of a motion vector. The chrominance motion vector generation unit selected by the selection unit generates the chrominance predictive vector, based on the motion vector information of luminance information. [0050] The motion picture decoding device of the present invention for making the inter-field motion compensation of a motion picture signal composed of a plurality of fields comprises a plurality of chrominance motion vector generation units generating a chrominance motion vector from a luminance motion vector; and a selection unit selecting one of the chrominance motion vector generation units used to generate a chrominance vector, using the reference field parity and coding field parity of a motion vector. The chrominance motion vector generation unit selected by the selection unit generates the chrominance predictive vector, based on the motion vector information of luminance information. [0051] According to the present invention, since a chrominance motion vector which is generated by a suitable method based on parities of a encoding/decoding field and a reference field, is used, the discrepancy of the chrominance motion vector caused by the difference of arrangement, or the way of assignment to a top and a bottom field of luminance pixels and chrominance pixels, is resolved. [0052] Additionally, by the present invention, a chrominance motion vector which is parallel to a luminance motion vector is obtained even in the case of fields with different parity and the problem of a shift of reference pixel position between luminance components and chrominance components in the conventional method, is resolved. BRIEF DESCRIPTION OF THE DRAWINGS [0053] FIG. 1 shows the configuration of an inter-frame predictive encoding device; [0054] FIG. 2 shows the respective positions of luminance and chrominance pixels and a field to which each of them belongs; [0055] FIG. 3 shows the respective vertical time and spatial positions of luminance and chrominance pixels in a field image; [0056] FIG. 4 shows the relation between a field and a frame in a frame encoding mode; [0057] FIG. 5 shows a predictive method in an inter-frame predictive encoding mode; [0058] FIG. 6 shows a predictive method in an inter-field predictive mode; [0059] FIG. 7 shows the coordinates of a field image; [0060] FIG. 8 shows the conventional calculation method of a motion vector between corresponding pixels between fields; [0061] FIG. 9 shows the conventional calculation method of a pixel pointed by a motion vector; [0062] FIG. 10 shows a conventional method for calculating a chrominance motion vector, using a luminance motion vector; [0063] FIG. 11 shows the calculation method of an interpolated pixel of a chrominance component; [0064] FIG. 12 shows the principle of conventional direct mode for explaining a zero vector between fields with different parity; [0065] FIG. 13 shows a conventional problem caused if a chrominance motion vector is calculated using a luminance motion vector when a reference field and a coding field are a bottom field and a top field, respectively; [0066] FIG. 14 shows a conventional problem caused if a chrominance motion vector is calculated using a luminance motion vector when a reference field and a coding field are a top field and a bottom field, respectively; [0067] FIG. 15 shows the method for generating a chrominance motion vector, using a luminance motion vector in the present invention; [0068] FIGS. 16 shows the operation of one preferred embodiment of the first chrominance motion vector generation unit of the present invention; [0069] FIG. 17 shows the operation of one preferred embodiment of the second chrominance motion vector generation unit of the present invention; [0070] FIG. 18 is the operation of one preferred embodiment of the third chrominance motion vector generation unit of the present invention; [0071] FIG. 19 is the operation of one preferred embodiment of the selection unit of the present invention; [0072] FIG. 20 is one example of the present invention which calculates a chrominance motion vector using a luminance motion vector when a reference field and a coding field are bottom and top fields, respectively; and [0073] FIG. 21 is one example of the present invention which calculates a chrominance motion vector using a luminance motion vector when a reference field and a coding field are top and bottom fields, respectively. [0074] FIG. 22 shows the operation of another preferred embodiment of the first chrominance motion vector generation unit of the present invention; [0075] FIG. 23 shows the operation of another preferred embodiment of the second chrominance motion vector generation unit of the present invention; [0076] FIG. 24 is the operation of another preferred embodiment of the third chrominance motion vector generation unit of the present invention; DESCRIPTION OF THE PREFERRED EMBODIMENTS [0077] Firstly, the principle of coding in the present invention is described. [0078] The motion picture encoding device of the present invention for making the inter-field motion compensation of a motion picture signal composed of a plurality of fields comprises a plurality of chrominance motion vector generation units generating a chrominance motion vector using a luminance motion vector; and a selection unit selecting one of the chrominance motion vector generation units used to generate a chrominance vector, using the respective parity of the reference field and a coding field of a motion vector. The chrominance motion vector generation unit selected by the selection unit generates the chrominance predictive vector, based on the motion vector information of luminance information. [0079] If a chrominance motion vector from a coding field to a reference field is parallel to a luminance motion vector from the coding field to the reference field, the spatial shift of the luminance motion vector and that of the chrominance motion vector become the same, that is, the relation of the spatial positions of the luminance motion vector and the chrominance motion vector is preserved, then the color displacement between fields disappears. [0080] Here, the important thing is that, in conventional method, even if the luminance motion vector is parallel to the chrominance motion vector based on a mathematical expression, each does not become parallel when those vectors are mapped on relations between luminance pixels and between chrominance pixels which compose each field. [0081] The plurality of chrominance motion vector generation units is include the three following types. [0082] A first chrominance motion vector generation unit is selected by the selection unit when a reference field and a coding field have the same parity. A second chrominance motion vector generation unit is selected by the selection unit when a reference field and a coding field are a top field and a bottom field, respectively. A third chrominance motion vector generation unit is selected by the selection unit when a reference field and a coding field are a bottom field and a top field, respectively. [0083] A method for calculating a chrominance motion vector parallel to a luminance motion vector depends on the coding field parity and reference field parity of a luminance motion vector. The calculation method differs in the following three case: a case where the coding field parity and reference field parity are the same, a case where the coding field and reference field are top and bottom fields, respectively, and a case where the coding field and reference field are bottom and top fields, respectively Therefore, in the present invention, an optimal one is selected from the three types of chrominance motion vector generation units calculating a chrominance motion vector parallel to a luminance motion vector, depending on the coding field and the reference field, and a chrominance motion vector is generated. [0084] Specifically, if the reference field parity and coding field parity are the same, the first chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector indicating the vertical displacement of one is luminance pixel of a field image by the value “1” of the vector component as units and a chrominance motion vector indicating the vertical displacement of one chrominance pixel of a field image by the value “1” of the vector component as units are MVy and MVCy, respectively. MVCy=Mvy /2  (3) [0085] If the reference field parity and coding field parity are top and bottom fields, respectively, the second chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector indicating the vertical displacement of one luminance pixel of a field image by the value “1” of the vector component as units and a chrominance motion vector indicating the vertical displacement of one chrominance pixel of a field image by the value “1” of the vector component as units are MVy and MVCy, respectively. MVCy=Mvy /2+0.25  (4) [0086] If the reference field parity and coding field parity are bottom and top fields, respectively, the third chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector indicating the vertical displacement of one luminance pixel of a field image by the value “1” of the vector component as units and a chrominance motion vector indicating the vertical displacement of one chrominance pixel of a field image by the value “1” of the vector component as units are MVy and MVCy, respectively. MVCy=Mvy /2−0.25  (5) [0087] Sometimes, the respective units of luminance and chrominance vectors vary, depending on its definition. In the case that it is defined that a luminance motion vector indicates the displacement of one luminance moving pixel when the component of the luminance motion vector changes by value 4 and that a chrominance motion vector indicates the displacement of one chrominance moving pixel when the component of the chrominance motion vector changes by value 8, if the reference field parity and coding field parity are the same, the first chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector and a chrominance motion vector are MVy and MVCy, respectively. MVCy=Mvy   (6) [0088] In the same definition, if the parity of reference field and coding field are top and bottom fields, respectively, the second chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector and a chrominance motion vector are MVy and MVCy, respectively. MVCy=Mvy+ 2  (7) [0089] In the same definition, if the reference field parity and coding field parity are bottom and top fields, respectively, the third chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector and a chrominance motion vector are MVy and MVCy, respectively. MVCy=Mvy −2  (8) [0090] The motion picture decoding device of the present invention basically has the same functions as the motion picture encoding device, and operates in the same way. [0091] The preferred embodiments of the encoding device are mainly described below. The encoding device has the configuration described above. Since the present invention relates to the vertical component of a motion vector, it is assumed for convenience sake that the horizontal components of all the motion vectors are 0. In this case, the decoding device has the same configuration as the encoding device. [0092] Preferred embodiments are described below assuming that AVC FCD is adopted. [0093] FIG. 15 shows a method for calculating a chrominance motion vector using a luminance motion vector. The preferred embodiment of a device generating a chrominance motion vector using a luminance motion vector in a field prediction comprises three types of chrominance motion vector generation units and one selection unit. [0094] The operation of the present invention shown in FIG. 15 is described below. Firstly it is assumed that a given luminance motion vector 231 is (MV_x,MV_y). This luminance vector is inputted to all of a first chrominance motion vector generation unit 233 , a second chrominance motion vector generation unit 234 and a third chrominance motion vector generation unit 235 . Then, their respective outputs are inputted to a selection unit 230 . The selection unit 230 selects one of the respective outputs of the first, second and third chrominance motion vector generation units, based on information about the coding field parity 237 of the inputted motion vector and its reference field parity 238 , and outputs it as a color motion vector 232 (MVC_x,MVC_y). [0095] FIG. 16 shows the operation of the first chrominance motion vector generation unit. In this preferred embodiment, a luminance motion vector 261 (MV_x,MV_y) is inputted to a first chrominance motion vector generation unit 260 , and a first chrominance motion vector candidate 262 (MVC 1 _x, MVC 1 _y) is outputted. The chrominance motion vector generation unit 260 calculates the first chrominance motion vector candidate 262 as follows using the luminance motion vector 261 . ( MVC 1 — x, MVC 1 — y )=( MV — x /2 , MV — y /2)  (9) Then, the calculated first chrominance motion vector candidate 262 is outputted to the selection unit. [0096] FIG. 17 shows the operation of the second chrominance motion vector generation unit. In this preferred embodiment a luminance motion vector 271 (MV_x,MV_y) is inputted to a second chrominance motion vector generation unit 270 , and a second chrominance motion vector candidate 272 (MVC 2 _x, MVC 2 _y) is outputted. The chrominance motion vector generation unit 270 calculates the second chrominance motion vector candidate 272 as follows using the luminance motion vector 271 . ( MVC 3 — x, MVC 3 — y )=( MV — x /2 , MV — y /2+1/4)  (10) Then, the calculated second chrominance motion vector candidate 272 is outputted to the selection unit. [0097] FIG. 18 shows the operation of the third chrominance motion vector generation unit. In this preferred embodiment, a luminance motion vector 281 (MV_x,MV_y) is inputted to a third chrominance motion vector generation unit 280 , and a third chrominance motion vector candidate 282 (MVC 2 _x, MVC 2 _y) is outputted. The chrominance motion vector generation unit 280 calculates the third chrominance motion vector candidate 282 as follows using the luminance motion vector 281 . ( MVC 3 — x,MVC 3 — y )=( MV — x /2 ,MV — y /2−1/4)  (11) Then, the calculated third chrominance motion vector candidate 282 is outputted to the selection unit. [0098] FIG. 19 shows the operation of one preferred embodiment of the selection unit 240 of the present invention. Firstly, in this preferred embodiment, a condition judgment table 241 is used for judgment of the coding field parity 247 of a motion vector and its reference field parity 248 , and the selection information 249 of a chrominance motion vector generation unit to be selected is outputted. In this preferred embodiment, if the reference field and coding field are the same, this condition judgment table 241 is used for outputting selection information indicating the selection of a first chrominance motion vector candidate 244 . If reference field and coding field are top and bottom fields, respectively, the condition judgment table 241 is used for outputting selection information indicating the selection of a second chrominance motion vector candidate 245 . If reference field and coding field are bottom and top fields, respectively, the condition judgment table 241 is used for outputting selection information indicating the selection of a third chrominance motion vector 246 candidate. [0099] In this case, the first, second or third chrominance motion vector candidates 244 , 245 and 246 are connected to 262 shown in FIG. 16, 272 shown in FIG. 17 and 282 shown in FIG. 18 , respectively. Then, a selector 243 selects one of the first, second and third chrominance motion vector candidates 244 , 245 and 246 , based on the selection information 249 , and outputs (MVC_x,MVC_y) as its chrominance motion vector 242 . [0100] FIG. 20 shows the operation of the present invention to calculate a chrominance vector using a luminance vector in the case where reference field and coding field are bottom and top fields, respectively. In the example shown in FIG. 20 , a luminance motion vector (MV_x,MV_y) used to predict a top coding field pixel 160 is assumed to be (0,1). In this case, a reference field bottom field luminance pixel position 161 is selected for the prediction of a luminance pixel 160 . The calculation process of a chrominance motion vector to be used to predict a top coding field chrominance pixel 162 is described below with reference to FIG. 15 . [0101] Firstly, in FIG. 20 , reference field and coding field are bottom and top fields, respectively. In this case, the condition judgment table 241 shown in FIG. 19 is used for selecting selection information 249 about the third chrominance motion vector candidate. According to equation (11), the third chrominance motion vector candidate is calculated as follows. ( MVC3_x , MVC3_y ) = ( MV_x / 2 , MV_y / 2 - 1 / 4 ) = ( 0 / 2 , 1 / 2 - 1 / 4 ) = ( 0 , 1 / 4 ) ( 12 ) Then, this value is outputted as the chrominance motion vector 242 shown in FIG. 19 . If this vector (0,¼) is applied to the top coding field chrominance pixel 162 , a bottom reference field chrominance pixel position 163 is used as a predicted value. In FIG. 20 , the vertical positional relation between pixels corresponds to a real pixel. As is clear from FIG. 20 , a luminance motion vector (0,1) and a chrominance motion vector (0,¼) are parallel. Thus, the color deviation between luminance and chrominance components, which is a conventional problem, can be solved by the present invention. [0102] Similarly, FIG. 21 shows the operation of the present invention to calculate a chrominance vector using a luminance vector in the case where reference field and coding field are top and bottom fields, respectively. [0103] In the example shown in FIG. 21 , a luminance motion vector (MV_x,MV_y) used to predict a bottom coding field pixel 170 is assumed to be (0,1). In this case, a top reference field luminance pixel position 171 is selected for the prediction of a luminance pixel 170 . The calculation process of a chrominance motion vector to be used to predict a bottom coding field chrominance pixel 172 is described below with reference to FIG. 15 . [0104] Firstly, in FIG. 21 , reference field and coding field are top and bottom fields, respectively. In this case, the condition judgment table 241 shown in FIG. 19 is used for selecting selection information 249 about the second chrominance motion vector candidate. According to equation (10), the candidate second chrominance motion vector is calculated as follows. ( MVC2_x , MVC2_y ) = ( MV_x / 2 , MV_y / 2 + 1 / 4 ) = ( 0 / 2 , 1 / 2 + 1 / 4 ) = ( 0 , 3 / 4 ) ( 13 ) Then, this value is outputted as the chrominance motion vector 242 shown in FIG. 19 . If this vector (0,¾) is applied to the bottom coding field chrominance pixel 172 , a top reference field chrominance pixel position 173 is used as a predictive position. In FIG. 21 , the vertical positional relation between pixels corresponds to a real one. As is clear from FIG. 21 , a luminance motion vector (0,1) and a chrominance motion vector (0,¾) are parallel. Thus, the color deviation between luminance and chrominance components, which is a conventional problem, can be solved by the present invention. [0105] Although in the examples shown in FIGS. 20 and 21 , the prediction of a specific vector is described, in a prediction between other parity fields, a prediction in which there is no deviation between luminance and chrominance can also realized by applying this preferred embodiment. [0106] When the reference field parity and coding field parity are the same, such color deviation does not occur. Therefore, the result of the first chrominance motion vector generation unit 233 of the present invention which has the same configuration as a chrominance motion vector generation unit 220 is selected from the conventional luminance motion vector shown in FIG. 10 , and is used as a color motion vector 232 . Since in this case, a chrominance motion vector calculated by the present invention is the same as conventional one, the description of this preferred embodiment is omitted here. [0107] In another aspect of the present invention, equations (9), (10) and (11) vary depending on the units of luminance and chrominance motion vectors [0108] FIGS. 22 through 24 show another embodiment of the first chrominance motion vector generation unit, the second chrominance motion vector generation unit and the third chrominance motion vector generation unit of the present invention. [0109] In the case that it is defined that a luminance motion vector indicates the displacement of one luminance moving pixel when the value of the luminance motion vector changes by four and that a chrominance motion vector indicates the displacement of one chrominance moving pixel when the value of the chrominance motion vector changes by eight, a chrominance motion vector generation unit 260 a calculates a candidate first chrominance motion vector 262 a using a luminance motion vector 261 a as follows. ( MVC 1 — x,MVC 1 — y )=( MV — x,MV — y )  (14) Then, the calculated first chrominance motion vector candidate 262 a is outputted to a selection unit. [0110] The chrominance motion vector generation unit 270 a calculates a second chrominance motion vector candidate 272 a using a luminance motion vector 271 a as follows. ( MVC 2 — x,MVC 2 — y )=( MV — x,MV — y +2)  (15) Then, the calculated second chrominance motion vector candidate 272 a is outputted to a selection unit. [0111] The chrominance motion vector generation unit 280 a calculates a third chrominance motion vector candidate 282 a using a luminance motion vector 281 a as follows. ( MVC 3 — x,MVC 3 — y )=( MV — x,MV — y −2)  (16) Then, the calculated third chrominance motion vector candidate 282 a is outputted to a selection unit. [0112] Although this preferred embodiment is described assuming that it adopts AVC FCD, this is just one preferred embodiment, and the format for encoding a field image is not limited to this. [0113] According to the present invention, a chrominance motion vector parallel to a luminance motion vector can also be calculated in fields with different parity, and the deviation in a reference pixel position between luminance and chrominance components, which are the conventional problem, can be solved accordingly.
When a prediction is made between fields with different parity, the predicative efficiency of a chrominance vector is improved by adaptively switching the generation of a chrominance motion vector depending on a encoding/decoding field parity (top/bottom) and a reference field parity (top/bottom), and the coding efficiency is improved accordingly.
Briefly summarize the main idea's components and working principles as described in the context.
[ "RELATED APPLICATION [0001] This application is a divisional of U.S. application Ser.", "No. 10/655,397, filed on Sep. 5, 2003, the disclosure of which is hereby incorporated herein by reference in its entirety.", "BACKGROUND OF THE INVENTION [0002] 1.", "Field of the Invention [0003] The present invention relates to a motion picture encoding device and a motion picture decoding device, which have an inter-field prediction mode.", "[0004] 2.", "Description of the Related Art [0005] Generally, motion picture data is large in size.", "Therefore, when motion picture data is transmitted from a transmitting device to a receiving device or when it is stored in a storage device, highly efficient encoding is applied to motion picture data.", "In this case, “highly efficient encoding”", "is an encoding process of converting a specific data string into another data string, and compressing the amount of data.", "[0006] There are two types of motion picture data: one is mainly composed of only frames and the other is composed of fields.", "A prior art for compressing a field image is mainly described below.", "[0007] As the highly efficient encoding method of motion picture data, a frame/field prediction encoding is known.", "[0008] FIG. 1 shows a block diagram of the configuration of the frame/field predictive encoding device.", "[0009] This encoding method utilizes the fact that a plurality of segments of motion picture data has high correlation in a time direction with each other.", "The operation shown in FIG. 1 is roughly described below.", "A subtracter 39 generates a differential image between an inputted original image and a predicted image, and an orthogonal transform unit 31 , a quantization unit 32 and a coefficient entropy encoding unit 40 encode the differential image.", "An inverse quantization unit 33 and an inverse orthogonal transform unit 34 reproduce the differential image from the output of the quantization unit 32 .", "Then, a decoded image generation unit 35 decodes the encoded image using the reproduced differential image reproduced by the decoded image generation unit 35 and the predicted image used at the time of encoding.", "A decoded image storage unit 36 stores the reproduced image.", "Then, motion vector calculation unit 37 calculates a motion vector between the reproduced image and a subsequent input image, and a predicted image generation unit 38 generates a predicted image using the motion vector The generated motion vector is encoded by a vector entropy encoding unit 41 and is outputted through a MUX 42 together with the encoded coefficient data encoded by the coefficient entropy encoding unit 40 .", "In other words, since in motion picture data, there is generally high similarity between frame/field data at a specific time and frame/field data at a subsequent time, the inter-frame/field predictive encoding method utilizes such a property.", "For example, in a data transmission system adopting the inter-frame/field predictive encoding method, a transmitting device generates motion vector data indicating displacement from previous frame/field image to a target frame/field image, and differential data between a predicted image in the target frame/field which is generated from the previous frame/field image using its motion vector data and a real image in the target frame/field, and transmits the motion vector data and the differential data to a receiving device.", "The receiving device reproduces the image in the target frame/field from the received motion vector data and differential data.", "[0010] So far, the summary of the frame/field predictive encoding has been described with reference to FIG. 1 .", "Next, frame predictive encoding and field predictive encoding are described below [0011] FIGS. 2 and 3 show a format used to encode a field image that is commonly used in ISO/IEC MPEG-2/MPEG-4 (hereinafter called “MPEG-2”", "and “MPEG-4”, respectively) and the final committee draft of ITU-T H[.", "].264/ISO/IEC MPEG-4 Part 10 (Advanced video coding (AVC))(“Joint Final Committee Draft (JFCD) of Joint Video Specification(ITU-T REC, H.264|ISO/IEC 14496-10 AVC)”, JVT-D157, or ISO/IEC JTC1/SO29/WG11 MPEG02/N492, July 2002, Klagenfurt, AT)(hereinafter called “AVC FCD”), which ITU-T and ISO/IEC jointly were standardizing as of August 2002.", "Specifically, each frame is composed of two fields: a top field and a bottom field.", "FIG. 2 shows the respective positions of a luminance pixels and a chrominance pixels, and a field to which each pixel belongs.", "As shown in FIG. 2 , odd number-ordered luminance lines, such as a first luminance line ( 50 a ), a third luminance line ( 50 b ), a fifth luminance line ( 50 c ), a seventh luminance line ( 50 d ), etc.", ", belong to the top field, and even number-ordered lines, such as a second luminance line ( 51 a ), a fourth luminance line ( 51 b ), a sixth luminance line ( 51 c ), a eighth luminance line ( 51 d ), etc.", ", belong to the bottom field.", "Similarly, odd number-ordered chrominance lines, such as a first chrominance line ( 52 a ), a third chrominance line ( 52 b ), etc.", ", belong to the top field, and even number-ordered chrominance line, such as a second chrominance ( 53 a ), a fourth chrominance line, etc.", ", belong to the bottom field.", "[0012] Each of the top and bottom fields indicates an image at a different time.", "Next, the time/spatial disposition of the top and bottom fields is described with reference to FIG. 3 .", "[0013] In FIGS. 3 and after, the technology of the present invention relates to the vertical component of a motion vector.", "Therefore, in this specification, horizontal pixel components are not shown, and all the horizontal components of the motion vector are assumed to be 0 for convenience sake.", "However, in order to show conventional problems and the effects of the present invention, the positional relation between luminance and chrominance in each field is accurately shown.", "[0014] In FIG. 3 , the vertical and horizontal axes represent the pixel position of a vertical component in each field and the elapse of time, respectively.", "Since there is no positional change in a field of the horizontal component of each image, in FIG. 3 , its horizontal pixel component is not shown nor is described.", "[0015] As shown in FIG. 3 , the pixel position of a chrominance component deviates from the pixel position in a field of a luminance component by a quarter vertical pixel.", "This is because relationship of pixel positions as shown in FIG. 2 is achieved when a frame is constructed from both Top and Bottom fields.", "If it is based on a NTSC format, each time interval between adjacent top and bottom fields ( 64 a : 65 a , 65 a : 64 b , etc.) is approximately 1/60 seconds.", "Each time interval between two consecutive top fields ( 64 a : 64 b , etc.) or between two consecutive bottom field ( 65 a : 65 b , etc.) are approximately 1/30 seconds.", "[0016] Next, the frame predictive encoding mode of a field image and its field prediction, which is adopted in MPEG-2 and AVC FCD, are described.", "[0017] FIG. 4 shows a method for constructing a frame using two consecutive fields (adjacent top and bottom fields) in a frame predictive mode.", "[0018] As shown in FIG. 4 , a frame is reconstructed by two time-consecutive fields (top and bottom fields).", "[0019] FIG. 5 shows a frame predictive mode.", "[0020] In FIG. 5 it is assumed that each frame, such as 84 a , 84 b , 84 c , etc.", ", is already reconstructed by two consecutive fields (top and bottom fields), as shown in FIG. 4 .", "In this frame predictive mode, a frame to be encoded which is composed of top and bottom fields is encoded.", "As a reference image, one reference frame is constructed by two consecutive fields (top and bottom fields) stored for reference use, and is used to predict the target frame to be encoded.", "Then, these two frame images are encoded according to the process flow shown in FIG. 1 .", "In the expression method of a motion vector of this frame predictive encoding mode, a zero vector, that is, ( 0 , 0 ) indicates a pixel located in the same spatial position.", "Specifically, the motion vector ( 0 , 0 ) of a luminance pixel 82 that belongs to frame# 2 ( 84 b ) indicates the pixel position 81 of frame# 1 ( 84 a ).", "[0021] Next, a field predictive encoding mode is described.", "[0022] FIG. 6 shows a predictive method in an inter-field predictive mode.", "[0023] In a field predictive mode, an encoding target is one top field ( 94 a , 94 b , etc.) or bottom field ( 95 a , 95 b , etc.) that is inputted as an original image.", "As a reference image, a top field or bottom field that is stored before can be used.", "In this case, it is generally defined that the fact that an original image field parity and a reference field parity are the same means that the original image field and the reference field both are top fields or bottom fields.", "For example, in a prediction 90 between fields with the same parity shown in FIG. 6 , an original image field ( 94 b ) and a reference field ( 94 a ) both are top fields.", "Similarly, it is generally defined that the fact that an original image field parity and a reference field parity are different means that one of original image and reference fields is a top field and the other is a bottom field.", "For example, in a prediction 91 between different parity fields shown in FIG. 6 , the original image field is a bottom field ( 95 a ) and the reference field is a top field ( 94 a ).", "Then, these original image and reference fields are encoded according to the process flow shown in FIG. 1 .", "[0024] In the prior art, in both frame and field modes, a motion vector is calculated based on a pixel position in each frame/field.", "Here, a conventional motion vector calculation method and a conventional pixel corresponding method used when a motion vector is given are described.", "[0025] FIG. 7 defines the coordinates of a frame/field image widely used in MPEG-2 coding, MPEG-1 coding, AVC FCD coding, etc.", "White circles in FIG. 7 are pixel definition positions in target frames/fields.", "In the coordinates of this frame/field image, the upper left corner is designated as the origin ( 0 , 0 ), and values 1, 2, 3, etc.", ", are sequentially assigned to both horizontal and vertical pixel definition positions.", "Specifically, the coordinates of a pixel that are located at the n-th horizontal position and the m-th vertical position are (n,m).", "Similarly, the coordinates of a position interpolated among the pixels are also defined.", "Specifically, since a position 180 marked with a black circle in FIG. 7 is located at 1.5 pixels in the horizontal direction from the pixel located in the upper left corner and at 2 pixels in the vertical direction, the coordinates of the position 180 is expressed as (1.5, 2).", "In a field image, there are only a half of the pixels of a frame image in the vertical direction.", "However, even in this case, the coordinates of a pixel are defined in the same way as in FIG. 7 , based on pixel positions located in each field.", "[0026] Next, the definition of a motion vector between fields is described using the coordinate system shown in FIG. 7 .", "[0027] FIG. 8 shows a conventional calculation method of a motion vector between corresponding pixels between fields.", "The definition of a motion vector requires the position of a coding field and the position of a reference field.", "A motion vector is defined between these two points.", "Thus, a motion vector between a coding field coordinates 201 (X s ,Y s ) and a reference field coordinates 202 (X d ,Y d ) is calculated.", "[0028] In the conventional calculation method of a motion vector between pixels corresponding to between-fields, a motion vector is calculated by the same method described below, regardless of whether the coding field or reference field is a top field or a bottom field.", "[0029] Specifically, coding field coordinates 201 (X s ,Y s ) and reference field coordinates 202 (X d ,Y d ) are inputted to a motion vector calculation unit 200 , and as a motion vector 203 between these two points, (X d −X s ,Y d −Y s ) is given.", "[0030] FIG. 9 shows a conventional method for calculating a pixel that is pointed by a motion vector defined between fields.", "In this case, it is assumed that a motion vector is calculated by the method shown in FIG. 8 .", "The calculation of reference frame/field coordinates requires a coding frame/field position and a motion vector.", "In the case shown in FIG. 9 , it is assumed that a motion vector 211 (X,Y) is given for coding field coordinates 212 (X s ,Y s ), and reference field coordinates can be calculated using both the motion vector 212 (X,Y) and the coding field coordinates 212 (X s ,Y s ).", "In the conventional calculation method of a motion vector between corresponding pixels between fields, a reference field position is calculated by the same method described below, regardless of whether the coding field or reference field is a top field or a bottom field.", "Specifically, a motion vector 211 (X,Y) and coding field coordinates 212 (X s ,Y s ) are inputted to a pixel corresponding unit 210 , and as reference field coordinates 213 , coordinates (X s +X,Y s +Y) is given.", "[0031] The definition of the relation between a vector and a pixel position applies to both a luminance component and chrominance component.", "In MPEG-1/MPEG-2/AVC FCD, which all are general motion picture encoding methods, only the vector of a luminance component is encoded, and the vector of a chrominance component is calculated by scaling down the luminance component.", "Particularly, in AVC FCD, since the number of vertical pixels and that of horizontal pixels of a chrominance component are a half of those of a luminance component, respectively, it is specified that a motion vector used to calculate the predictive pixel of a chrominance component should be obtained by accurately scaling down the motion vector of the luminance component to a half.", "[0032] FIG. 10 shows a conventional method for calculating a chrominance motion vector using a luminance motion vector.", "[0033] Specifically, if a luminance motion vector 221 and a chrominance motion vector 222 are (MV_x,MV_y) and (MVC_x, MVC_y), respectively, a chrominance motion vector generation unit 220 can calculate a chrominance motion vector 222 according to the following equation.", "( MVC — x, MVC — y )=( MV — x /2 ,MV — y /2) (1) This conventional calculation method can be used regardless of whether a motion vector is used for predicttion between fields with the same parity or between fields with different parity.", "[0034] In AVC FCD, as the accuracy of the motion vector of a luminance component, 1/4 pixel accuracy can be applied.", "Therefore, as a result of equation (1), as the accuracy of the motion vector of a chrominance component, a vector having 1/8 pixel accuracy, that is, accuracy at the decimal fraction, can be used.", "[0035] FIG. 11 shows the calculation method of the interpolated pixel of a chrominance component that is defined in AVC FCD.", "[0036] In FIG. 11 , a black circle and a white circle represent an integer pixel and an interpolated pixel, respectively.", "In this case, the horizontal coordinate of an interpolated pixel G( 256 ) is obtained by internally dividing each horizontal coordinate between points A( 250 ) and C( 252 ) at a ratio α:1-α, and the vertical coordinate can be obtained by internally dividing each vertical coordinate between points A( 250 ) and B( 251 ) at β:1-β.", "In this case, α and β are a value between 0 and 1.", "An interpolated pixel G( 256 ) defined by such positions can be roughly calculated as follows using integer pixels A( 250 ), B( 251 ), C( 252 ) and D( 253 ), which are located around the interpolated pixel G( 256 ), and using β and β.", "G =(1−α)·(1−β)· A +(1−α)·β· B +α·(1−β)· C+α·βD (2) [0037] The interpolated pixel calculation method of a chrominance component, using the method shown in FIG. 11 is just one example, and there is no problem in using another calculation method.", "[0038] In the case of this field encoding mode, in a prediction in which an original image field and a reference field are different, that is, between fields with different parity, the respective zero vectors of the motion vector of a luminance component and that of a chrominance component are not parallel in the definition of AVC FCD.", "Specifically, if a prediction is made using the motion vector of a chrominance component calculated using the motion vector of a luminance component according to the conventional definition, a pixel located in a position spatially deviated from that of the luminance component is to be referenced.", "This fact is described below with reference to FIG. 12 .", "In FIG. 12 , it is assumed that a top field 130 , a bottom field 131 and a top field 132 continue timewise.", "In this case, bottom field 131 is to be encoded using top field 130 .", "In this inter-field encoding, the vertical motion vector in the same line of each field is defined to be zero.", "Therefore, if a zero vector ( 0 , 0 ) is assigned to a luminance pixel 133 a that belongs to the second line of bottom field 131 , this pixel can be predicted from a pixel 135 a in top field 130 .", "Similarly, when a zero vector ( 0 , 0 ) is assigned to a chrominance pixel 133 a which belongs to the first line of the bottom field 131 , this pixel is predicted from the pixel 137 a which is in the first line of chrominance of the top field 130 .", "Similarly, a luminance pixel 133 b in the third line and a chrominance pixel 134 b , which belong to top field 132 are predicted from pixels 135 b in the third line of luminance and 137 b in the second line of chrominance in bottom field 131 , respectively.", "Since essentially it is preferable that a chrominance motion vector and a luminance motion vector are parallel, chrominance pixels 134 a and 134 b should be predicted from the positions 136 a and 136 b , respectively, if a luminance motion vector is as it is.", "[0039] As described earlier, in a prediction between fields with different parity, the fact that the respective zero vectors of luminance and chrominance are not parallel is explained.", "In the case of AVC FCD, this fact causes the following problems for all vectors in a prediction between fields with different parity.", "FIGS. 13 and 14 show such problems.", "Problems in the case of AVC FCD are described below.", "In the explanation below, a horizontal component of a motion vector is set to zero in all cases for brevity.", "[0040] FIG. 13 shows a conventional problem caused if a chrominance motion vector is conventionally calculated using a luminance motion vector when a reference field and a coding field are a bottom field and a top field, respectively.", "In AVC FCD, since, as is clear from equation (1), it is specified that the number of vertical and horizontal pixels of a chrominance component are a half of those of a luminance component, a motion vector used to calculate the predictive pixel of a chrominance should be scaled down to a half of the motion vector of a luminance component.", "This is regardless of whether a motion vector is used for predicttion between frames, between fields with the same parity or between fields with different parity.", "[0041] It is shown below that this definition causes a problem when a chrominance motion vector is calculated using a luminance motion vector defined between fields with different parity.", "In FIG. 13 , a coding field top field luminance pixel 140 in the first line has (0,1) as a predictive vector, and as a result, it points a bottom reference field luminance pixel position 141 in the second line as a predictive value.", "[0042] In this case, a chrominance motion vector that belongs to the same block is calculated to be (0,½), according to equation (1).", "If a prediction is made using motion vector (0,½) as a predictive value of a coding field top field chrominance pixel 142 in the first line, a pixel position 143 is used as predicted value, which shifts downward by half a pixel from a pixel in the first line of a bottom reference field chrominance component.", "[0043] In this case, a luminance motion vector (0,1) and a chrominance vector (0,½) are not parallel.", "It is preferable to use a bottom reference field chrominance predictive pixel position 145 to which a chrominance motion vector parallel to a luminance motion vector is applied.", "[0044] FIGS. 14 shows a conventional problem caused if a chrominance motion vector is calculated using a luminance motion vector when a reference field and a coding field are a top field and a bottom field, respectively.", "As described in FIG. 13 , in FIG. 14 , a bottom coding field luminance pixel 150 in the first line has (0,1) as a predictive vector, and as a result, it points a reference top field luminance pixel position 151 in the second line as a predictive value.", "[0045] In this case, a chrominance motion vector that belongs to the same block is calculated to be (0,½), according to equation (1).", "If a prediction is made using motion vector (0,½) as a predictive value of a bottom coding field chrominance pixel 152 , a pixel position 153 is used as predicted value which is shifted by half a pixel from a top reference field chrominance pixel position 153 in the first line.", "[0046] In this case, a luminance motion vector (0,1) and a chrominance vector (0,½) are not parallel.", "It is preferable to use a top reference field chrominance predictive pixel position 155 to which a chrominance motion vector parallel to a luminance motion vector is applied.", "[0047] As described above, if a reference field parity and a coding field parity are different, according to the conventional predictive method, a pixel located in the position of a luminance component spatially deviated from that of the chrominance component is to be referenced, and a predictive image, in which a pixel located in the position of a luminance component is spatially deviated from that of the chrominance component, is generated not only for a zero vector but for all the vectors.", "Note that, in the above explanation, vector are said to be parallel or not parallel by considering the case where the direction in time of a luminance motion vector and a chrominance motion vector, that is, time direction from coding field to reference field in included in a motion vector.", "The same is true below.", "SUMMARY OF THE INVENTION [0048] It is an object of the present invention to provide a motion picture encoding device and a motion picture decoding device capable of particularly improving predictive efficiency of a chrominance component and improving encoding efficiency accordingly, in encoding between different field images.", "[0049] The motion picture encoding device of the present invention for making the inter-Field motion compensation of a motion picture signal composed of a plurality of fields comprises a plurality of chrominance motion vector generation units generating a chrominance motion vector using a luminance motion vector in a motion picture encoding device;", "and a selection unit selecting one of the chrominance motion vector generation units used to generate a chrominance vector, using the reference field parity and coding field parity of a motion vector.", "The chrominance motion vector generation unit selected by the selection unit generates the chrominance predictive vector, based on the motion vector information of luminance information.", "[0050] The motion picture decoding device of the present invention for making the inter-field motion compensation of a motion picture signal composed of a plurality of fields comprises a plurality of chrominance motion vector generation units generating a chrominance motion vector from a luminance motion vector;", "and a selection unit selecting one of the chrominance motion vector generation units used to generate a chrominance vector, using the reference field parity and coding field parity of a motion vector.", "The chrominance motion vector generation unit selected by the selection unit generates the chrominance predictive vector, based on the motion vector information of luminance information.", "[0051] According to the present invention, since a chrominance motion vector which is generated by a suitable method based on parities of a encoding/decoding field and a reference field, is used, the discrepancy of the chrominance motion vector caused by the difference of arrangement, or the way of assignment to a top and a bottom field of luminance pixels and chrominance pixels, is resolved.", "[0052] Additionally, by the present invention, a chrominance motion vector which is parallel to a luminance motion vector is obtained even in the case of fields with different parity and the problem of a shift of reference pixel position between luminance components and chrominance components in the conventional method, is resolved.", "BRIEF DESCRIPTION OF THE DRAWINGS [0053] FIG. 1 shows the configuration of an inter-frame predictive encoding device;", "[0054] FIG. 2 shows the respective positions of luminance and chrominance pixels and a field to which each of them belongs;", "[0055] FIG. 3 shows the respective vertical time and spatial positions of luminance and chrominance pixels in a field image;", "[0056] FIG. 4 shows the relation between a field and a frame in a frame encoding mode;", "[0057] FIG. 5 shows a predictive method in an inter-frame predictive encoding mode;", "[0058] FIG. 6 shows a predictive method in an inter-field predictive mode;", "[0059] FIG. 7 shows the coordinates of a field image;", "[0060] FIG. 8 shows the conventional calculation method of a motion vector between corresponding pixels between fields;", "[0061] FIG. 9 shows the conventional calculation method of a pixel pointed by a motion vector;", "[0062] FIG. 10 shows a conventional method for calculating a chrominance motion vector, using a luminance motion vector;", "[0063] FIG. 11 shows the calculation method of an interpolated pixel of a chrominance component;", "[0064] FIG. 12 shows the principle of conventional direct mode for explaining a zero vector between fields with different parity;", "[0065] FIG. 13 shows a conventional problem caused if a chrominance motion vector is calculated using a luminance motion vector when a reference field and a coding field are a bottom field and a top field, respectively;", "[0066] FIG. 14 shows a conventional problem caused if a chrominance motion vector is calculated using a luminance motion vector when a reference field and a coding field are a top field and a bottom field, respectively;", "[0067] FIG. 15 shows the method for generating a chrominance motion vector, using a luminance motion vector in the present invention;", "[0068] FIGS. 16 shows the operation of one preferred embodiment of the first chrominance motion vector generation unit of the present invention;", "[0069] FIG. 17 shows the operation of one preferred embodiment of the second chrominance motion vector generation unit of the present invention;", "[0070] FIG. 18 is the operation of one preferred embodiment of the third chrominance motion vector generation unit of the present invention;", "[0071] FIG. 19 is the operation of one preferred embodiment of the selection unit of the present invention;", "[0072] FIG. 20 is one example of the present invention which calculates a chrominance motion vector using a luminance motion vector when a reference field and a coding field are bottom and top fields, respectively;", "and [0073] FIG. 21 is one example of the present invention which calculates a chrominance motion vector using a luminance motion vector when a reference field and a coding field are top and bottom fields, respectively.", "[0074] FIG. 22 shows the operation of another preferred embodiment of the first chrominance motion vector generation unit of the present invention;", "[0075] FIG. 23 shows the operation of another preferred embodiment of the second chrominance motion vector generation unit of the present invention;", "[0076] FIG. 24 is the operation of another preferred embodiment of the third chrominance motion vector generation unit of the present invention;", "DESCRIPTION OF THE PREFERRED EMBODIMENTS [0077] Firstly, the principle of coding in the present invention is described.", "[0078] The motion picture encoding device of the present invention for making the inter-field motion compensation of a motion picture signal composed of a plurality of fields comprises a plurality of chrominance motion vector generation units generating a chrominance motion vector using a luminance motion vector;", "and a selection unit selecting one of the chrominance motion vector generation units used to generate a chrominance vector, using the respective parity of the reference field and a coding field of a motion vector.", "The chrominance motion vector generation unit selected by the selection unit generates the chrominance predictive vector, based on the motion vector information of luminance information.", "[0079] If a chrominance motion vector from a coding field to a reference field is parallel to a luminance motion vector from the coding field to the reference field, the spatial shift of the luminance motion vector and that of the chrominance motion vector become the same, that is, the relation of the spatial positions of the luminance motion vector and the chrominance motion vector is preserved, then the color displacement between fields disappears.", "[0080] Here, the important thing is that, in conventional method, even if the luminance motion vector is parallel to the chrominance motion vector based on a mathematical expression, each does not become parallel when those vectors are mapped on relations between luminance pixels and between chrominance pixels which compose each field.", "[0081] The plurality of chrominance motion vector generation units is include the three following types.", "[0082] A first chrominance motion vector generation unit is selected by the selection unit when a reference field and a coding field have the same parity.", "A second chrominance motion vector generation unit is selected by the selection unit when a reference field and a coding field are a top field and a bottom field, respectively.", "A third chrominance motion vector generation unit is selected by the selection unit when a reference field and a coding field are a bottom field and a top field, respectively.", "[0083] A method for calculating a chrominance motion vector parallel to a luminance motion vector depends on the coding field parity and reference field parity of a luminance motion vector.", "The calculation method differs in the following three case: a case where the coding field parity and reference field parity are the same, a case where the coding field and reference field are top and bottom fields, respectively, and a case where the coding field and reference field are bottom and top fields, respectively Therefore, in the present invention, an optimal one is selected from the three types of chrominance motion vector generation units calculating a chrominance motion vector parallel to a luminance motion vector, depending on the coding field and the reference field, and a chrominance motion vector is generated.", "[0084] Specifically, if the reference field parity and coding field parity are the same, the first chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector indicating the vertical displacement of one is luminance pixel of a field image by the value “1”", "of the vector component as units and a chrominance motion vector indicating the vertical displacement of one chrominance pixel of a field image by the value “1”", "of the vector component as units are MVy and MVCy, respectively.", "MVCy=Mvy /2 (3) [0085] If the reference field parity and coding field parity are top and bottom fields, respectively, the second chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector indicating the vertical displacement of one luminance pixel of a field image by the value “1”", "of the vector component as units and a chrominance motion vector indicating the vertical displacement of one chrominance pixel of a field image by the value “1”", "of the vector component as units are MVy and MVCy, respectively.", "MVCy=Mvy /2+0.25 (4) [0086] If the reference field parity and coding field parity are bottom and top fields, respectively, the third chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector indicating the vertical displacement of one luminance pixel of a field image by the value “1”", "of the vector component as units and a chrominance motion vector indicating the vertical displacement of one chrominance pixel of a field image by the value “1”", "of the vector component as units are MVy and MVCy, respectively.", "MVCy=Mvy /2−0.25 (5) [0087] Sometimes, the respective units of luminance and chrominance vectors vary, depending on its definition.", "In the case that it is defined that a luminance motion vector indicates the displacement of one luminance moving pixel when the component of the luminance motion vector changes by value 4 and that a chrominance motion vector indicates the displacement of one chrominance moving pixel when the component of the chrominance motion vector changes by value 8, if the reference field parity and coding field parity are the same, the first chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector and a chrominance motion vector are MVy and MVCy, respectively.", "MVCy=Mvy (6) [0088] In the same definition, if the parity of reference field and coding field are top and bottom fields, respectively, the second chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector and a chrominance motion vector are MVy and MVCy, respectively.", "MVCy=Mvy+ 2 (7) [0089] In the same definition, if the reference field parity and coding field parity are bottom and top fields, respectively, the third chrominance motion vector generation unit calculates a chrominance motion vector as follows, assuming that a luminance motion vector and a chrominance motion vector are MVy and MVCy, respectively.", "MVCy=Mvy −2 (8) [0090] The motion picture decoding device of the present invention basically has the same functions as the motion picture encoding device, and operates in the same way.", "[0091] The preferred embodiments of the encoding device are mainly described below.", "The encoding device has the configuration described above.", "Since the present invention relates to the vertical component of a motion vector, it is assumed for convenience sake that the horizontal components of all the motion vectors are 0.", "In this case, the decoding device has the same configuration as the encoding device.", "[0092] Preferred embodiments are described below assuming that AVC FCD is adopted.", "[0093] FIG. 15 shows a method for calculating a chrominance motion vector using a luminance motion vector.", "The preferred embodiment of a device generating a chrominance motion vector using a luminance motion vector in a field prediction comprises three types of chrominance motion vector generation units and one selection unit.", "[0094] The operation of the present invention shown in FIG. 15 is described below.", "Firstly it is assumed that a given luminance motion vector 231 is (MV_x,MV_y).", "This luminance vector is inputted to all of a first chrominance motion vector generation unit 233 , a second chrominance motion vector generation unit 234 and a third chrominance motion vector generation unit 235 .", "Then, their respective outputs are inputted to a selection unit 230 .", "The selection unit 230 selects one of the respective outputs of the first, second and third chrominance motion vector generation units, based on information about the coding field parity 237 of the inputted motion vector and its reference field parity 238 , and outputs it as a color motion vector 232 (MVC_x,MVC_y).", "[0095] FIG. 16 shows the operation of the first chrominance motion vector generation unit.", "In this preferred embodiment, a luminance motion vector 261 (MV_x,MV_y) is inputted to a first chrominance motion vector generation unit 260 , and a first chrominance motion vector candidate 262 (MVC 1 _x, MVC 1 _y) is outputted.", "The chrominance motion vector generation unit 260 calculates the first chrominance motion vector candidate 262 as follows using the luminance motion vector 261 .", "( MVC 1 — x, MVC 1 — y )=( MV — x /2 , MV — y /2) (9) Then, the calculated first chrominance motion vector candidate 262 is outputted to the selection unit.", "[0096] FIG. 17 shows the operation of the second chrominance motion vector generation unit.", "In this preferred embodiment a luminance motion vector 271 (MV_x,MV_y) is inputted to a second chrominance motion vector generation unit 270 , and a second chrominance motion vector candidate 272 (MVC 2 _x, MVC 2 _y) is outputted.", "The chrominance motion vector generation unit 270 calculates the second chrominance motion vector candidate 272 as follows using the luminance motion vector 271 .", "( MVC 3 — x, MVC 3 — y )=( MV — x /2 , MV — y /2+1/4) (10) Then, the calculated second chrominance motion vector candidate 272 is outputted to the selection unit.", "[0097] FIG. 18 shows the operation of the third chrominance motion vector generation unit.", "In this preferred embodiment, a luminance motion vector 281 (MV_x,MV_y) is inputted to a third chrominance motion vector generation unit 280 , and a third chrominance motion vector candidate 282 (MVC 2 _x, MVC 2 _y) is outputted.", "The chrominance motion vector generation unit 280 calculates the third chrominance motion vector candidate 282 as follows using the luminance motion vector 281 .", "( MVC 3 — x,MVC 3 — y )=( MV — x /2 ,MV — y /2−1/4) (11) Then, the calculated third chrominance motion vector candidate 282 is outputted to the selection unit.", "[0098] FIG. 19 shows the operation of one preferred embodiment of the selection unit 240 of the present invention.", "Firstly, in this preferred embodiment, a condition judgment table 241 is used for judgment of the coding field parity 247 of a motion vector and its reference field parity 248 , and the selection information 249 of a chrominance motion vector generation unit to be selected is outputted.", "In this preferred embodiment, if the reference field and coding field are the same, this condition judgment table 241 is used for outputting selection information indicating the selection of a first chrominance motion vector candidate 244 .", "If reference field and coding field are top and bottom fields, respectively, the condition judgment table 241 is used for outputting selection information indicating the selection of a second chrominance motion vector candidate 245 .", "If reference field and coding field are bottom and top fields, respectively, the condition judgment table 241 is used for outputting selection information indicating the selection of a third chrominance motion vector 246 candidate.", "[0099] In this case, the first, second or third chrominance motion vector candidates 244 , 245 and 246 are connected to 262 shown in FIG. 16, 272 shown in FIG. 17 and 282 shown in FIG. 18 , respectively.", "Then, a selector 243 selects one of the first, second and third chrominance motion vector candidates 244 , 245 and 246 , based on the selection information 249 , and outputs (MVC_x,MVC_y) as its chrominance motion vector 242 .", "[0100] FIG. 20 shows the operation of the present invention to calculate a chrominance vector using a luminance vector in the case where reference field and coding field are bottom and top fields, respectively.", "In the example shown in FIG. 20 , a luminance motion vector (MV_x,MV_y) used to predict a top coding field pixel 160 is assumed to be (0,1).", "In this case, a reference field bottom field luminance pixel position 161 is selected for the prediction of a luminance pixel 160 .", "The calculation process of a chrominance motion vector to be used to predict a top coding field chrominance pixel 162 is described below with reference to FIG. 15 .", "[0101] Firstly, in FIG. 20 , reference field and coding field are bottom and top fields, respectively.", "In this case, the condition judgment table 241 shown in FIG. 19 is used for selecting selection information 249 about the third chrominance motion vector candidate.", "According to equation (11), the third chrominance motion vector candidate is calculated as follows.", "( MVC3_x , MVC3_y ) = ( MV_x / 2 , MV_y / 2 - 1 / 4 ) = ( 0 / 2 , 1 / 2 - 1 / 4 ) = ( 0 , 1 / 4 ) ( 12 ) Then, this value is outputted as the chrominance motion vector 242 shown in FIG. 19 .", "If this vector (0,¼) is applied to the top coding field chrominance pixel 162 , a bottom reference field chrominance pixel position 163 is used as a predicted value.", "In FIG. 20 , the vertical positional relation between pixels corresponds to a real pixel.", "As is clear from FIG. 20 , a luminance motion vector (0,1) and a chrominance motion vector (0,¼) are parallel.", "Thus, the color deviation between luminance and chrominance components, which is a conventional problem, can be solved by the present invention.", "[0102] Similarly, FIG. 21 shows the operation of the present invention to calculate a chrominance vector using a luminance vector in the case where reference field and coding field are top and bottom fields, respectively.", "[0103] In the example shown in FIG. 21 , a luminance motion vector (MV_x,MV_y) used to predict a bottom coding field pixel 170 is assumed to be (0,1).", "In this case, a top reference field luminance pixel position 171 is selected for the prediction of a luminance pixel 170 .", "The calculation process of a chrominance motion vector to be used to predict a bottom coding field chrominance pixel 172 is described below with reference to FIG. 15 .", "[0104] Firstly, in FIG. 21 , reference field and coding field are top and bottom fields, respectively.", "In this case, the condition judgment table 241 shown in FIG. 19 is used for selecting selection information 249 about the second chrominance motion vector candidate.", "According to equation (10), the candidate second chrominance motion vector is calculated as follows.", "( MVC2_x , MVC2_y ) = ( MV_x / 2 , MV_y / 2 + 1 / 4 ) = ( 0 / 2 , 1 / 2 + 1 / 4 ) = ( 0 , 3 / 4 ) ( 13 ) Then, this value is outputted as the chrominance motion vector 242 shown in FIG. 19 .", "If this vector (0,¾) is applied to the bottom coding field chrominance pixel 172 , a top reference field chrominance pixel position 173 is used as a predictive position.", "In FIG. 21 , the vertical positional relation between pixels corresponds to a real one.", "As is clear from FIG. 21 , a luminance motion vector (0,1) and a chrominance motion vector (0,¾) are parallel.", "Thus, the color deviation between luminance and chrominance components, which is a conventional problem, can be solved by the present invention.", "[0105] Although in the examples shown in FIGS. 20 and 21 , the prediction of a specific vector is described, in a prediction between other parity fields, a prediction in which there is no deviation between luminance and chrominance can also realized by applying this preferred embodiment.", "[0106] When the reference field parity and coding field parity are the same, such color deviation does not occur.", "Therefore, the result of the first chrominance motion vector generation unit 233 of the present invention which has the same configuration as a chrominance motion vector generation unit 220 is selected from the conventional luminance motion vector shown in FIG. 10 , and is used as a color motion vector 232 .", "Since in this case, a chrominance motion vector calculated by the present invention is the same as conventional one, the description of this preferred embodiment is omitted here.", "[0107] In another aspect of the present invention, equations (9), (10) and (11) vary depending on the units of luminance and chrominance motion vectors [0108] FIGS. 22 through 24 show another embodiment of the first chrominance motion vector generation unit, the second chrominance motion vector generation unit and the third chrominance motion vector generation unit of the present invention.", "[0109] In the case that it is defined that a luminance motion vector indicates the displacement of one luminance moving pixel when the value of the luminance motion vector changes by four and that a chrominance motion vector indicates the displacement of one chrominance moving pixel when the value of the chrominance motion vector changes by eight, a chrominance motion vector generation unit 260 a calculates a candidate first chrominance motion vector 262 a using a luminance motion vector 261 a as follows.", "( MVC 1 — x,MVC 1 — y )=( MV — x,MV — y ) (14) Then, the calculated first chrominance motion vector candidate 262 a is outputted to a selection unit.", "[0110] The chrominance motion vector generation unit 270 a calculates a second chrominance motion vector candidate 272 a using a luminance motion vector 271 a as follows.", "( MVC 2 — x,MVC 2 — y )=( MV — x,MV — y +2) (15) Then, the calculated second chrominance motion vector candidate 272 a is outputted to a selection unit.", "[0111] The chrominance motion vector generation unit 280 a calculates a third chrominance motion vector candidate 282 a using a luminance motion vector 281 a as follows.", "( MVC 3 — x,MVC 3 — y )=( MV — x,MV — y −2) (16) Then, the calculated third chrominance motion vector candidate 282 a is outputted to a selection unit.", "[0112] Although this preferred embodiment is described assuming that it adopts AVC FCD, this is just one preferred embodiment, and the format for encoding a field image is not limited to this.", "[0113] According to the present invention, a chrominance motion vector parallel to a luminance motion vector can also be calculated in fields with different parity, and the deviation in a reference pixel position between luminance and chrominance components, which are the conventional problem, can be solved accordingly." ]
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a continuation from U.S. patent application Ser. No. 12/911,541, filed Oct. 25, 2010, which is a continuation from U.S. patent application Ser. No. 11/551,684, filed Oct. 20, 2006, now U.S. Pat. No. 7,853,316, issued Dec. 14, 2010, which claims priority to U.S. Provisional Patent Application Ser. No. 60/728,481, filed Oct. 20, 2005, and which is a continuation-in-part “CIP” of U.S. patent application Ser. No. 10/548,982, which was filed Sep. 7, 2005 and granted a U.S. national stage filing date of May 2, 2006, now U.S. Pat. No. 7,711,413, issued May 4, 2010, which claims priority to PCT International Patent Application No. PCT/US2004/012773, filed Apr. 23, 2004 and which claims priority to U.S. Provisional Patent Application Ser. No. 60/466,215, filed Apr. 28, 2003, all of which are herein expressly incorporated by reference. BACKGROUND OF THE INVENTION [0002] The present invention relates to catheter probes based on the use of a fiber that does not rotate. More specifically, the present invention relates to optical coherence tomography based on the use of an optical fiber that does not rotate, which is enclosed in a catheter portion. [0003] Myocardial infarction or heart attack remains the leading cause of death in our society. Unfortunately, most of us can identify a family member or close friend that has suffered from a myocardial infarction. Until recently many investigators believed that coronary arteries critically blocked with atherosclerotic plaque that subsequently progressed to total occlusion was the primary mechanism for myocardial infarction. Recent evidence from many investigational studies, however, clearly indicates that most infarctions are due to sudden rupture of non-critically stenosed coronary arteries due to sudden plaque rupture. For example, Little et al. (Little, W C, Downes, T R, Applegate, R J. The underlying coronary lesion in myocardial infarction: implications for coronary angiography. Clin Cardiol 1991, 14: 868-874, incorporated by reference herein) observed that approximately 70% of patients suffering from an acute plaque rupture were initiated on plaques that were less than 50% occluded as revealed by previous coronary angiography. This and similar observations have been confirmed by other investigators (Nissen, S. Coronary angiography and intravascular ultrasound. Am J Cardiol 2001, 87 (suppl): 15A -20 A, incorporated by reference herein). [0004] The development of technologies to identify these unstable plaques holds the potential to decrease substantially the incidence of acute coronary syndromes that often lead to premature death. Unfortunately, no methods are currently available to the cardiologist that may be applied to specify which coronary plaques are vulnerable and thus prone to rupture. Although treadmill testing has been used for decades to identify patients at greater cardiovascular risk, this approach does not have the specificity to differentiate between stable and vulnerable plaques that are prone to rupture and frequently result in myocardial infarction. Inasmuch as a great deal of information exists regarding the pathology of unstable plaques (determined at autopsy) technologies based upon identifying the well described pathologic appearance of the vulnerable plaque offers a promising long term strategy to solve this problem. [0005] The unstable plaque was first identified and characterized by pathologists in the early 1980's. Davis and coworkers noted that with the reconstruction of serial histological sections in patients with acute myocardial infarctions associated with death, a rupture or fissuring of athermanous plaque was evident (Davis M J, Thomas A C. Plaque fissuring: the cause of acute myocardial infarction, sudden death, and crescendo angina. Br Heart J 1985; 53: 3 63-37 3, incorporated by reference herein). Ulcerated plaques were further characterized as having a thin fibrous cap, increased macrophages with decreased smooth muscle cells and an increased lipid core when compared to non-ulcerated atherosclerotic plaques in human aortas (Davis M J, Richardson E D, Woolf N. Katz O R, Mann J. Risk of thrombosis in human atherosclerotic plaques: role of extracellular lipid, macrophage, and smooth muscle cell content, incorporated by reference herein). Furthermore, no correlation in size of lipid pool and percent stenosis was observed when imaging by coronary angiography. In fact, most cardiologists agree that unstable plaques progress to more stenotic yet stable plaques through progression via rupture with the formation of a mural thrombus and plaque remodeling, but without complete luminal occlusion (Topol E J, Rabbaic R. Strategies to achieve coronary arterial plaque stabilization. Cardiovasc Res 1999; 41: 402-417, incorporated by reference herein). Neovascularization with intra-plaque hemorrhage may also play a role in this progression from small lesions, i.e., those less than about 50% occluded, to larger significant plaques. Yet, if the unique features of unstable plaque could be recognized by the cardiologist and then stabilized, a dramatic decrease may be realized in both acute myocardial infarction and unstable angina syndromes, and in the sudden progression of coronary artery disease. SUMMARY OF THE INVENTION [0006] The present invention uses depth-resolved light reflection or Optical Coherence Tomography (OCT) to identify the pathological features that have been identifie3d in the vulnerable plaque. In OCT, light from a broad band light source or tunable laser source is split by an optical fiber splitter with one fiber directing light to the vessel wall and the other fiber directing light to a moving reference mirror. The distal end of the optical fiber is interfaced with a catheter for interrogation of the coronary artery during a heart catheterization procedure. The reflected light from the plaque is recombined with the signal from the reference mirror forming interference fringes (measured by an photovoltaic detector) allowing precise depth-resolved imaging of the plaque on a micron scale. [0007] OCT uses a superluminescent diode source or tunable laser source emitting a 1300 nm wave length, with a 50-250 nm band width (distribution of wave length) to make in situ tomographic images with axial resolution of 2-20 μm and tissue penetration of 2-3 mm. OCT has the potential to image tissues at the level of a single cell. In fact, the inventors have recently utilized broader band width optical sources so that axial resolution is improved to 4 um or less. With such resolution, OCT can be applied to visualize intimal caps, their thickness, and details of structure including fissures, the size and extent of the underlying lipid pool and the presence of inflammatory cells. Moreover, near infrared light sources used in OCT instrumentation can penetrate into heavily calcified tissue regions characteristic of advanced coronary artery disease. With cellular resolution, application of OCT may be used to identify other details of the vulnerable plaque such as infiltration of monocytes and macrophages. In short, application of OCT can provide detailed images of a pathologic specimen without cutting or disturbing the tissue. [0008] One concern regarding application of this technology to image atherosclerotic plaques within the arterial lumen is the strong scattering of light due to the presence of red blood cells. Once a catheter system is positioned in a coronary artery, the blood flow between the OCT optical fiber and artery can obscure light penetration into the vessel wall. One proposed solution is the use of saline flushes. Saline use is limited in duration, however, since myocardial ischemia eventually occurs in the distal myocardium. The inventors have proposed the use of artificial blood substitutes in the place of saline. Artificial hemoglobin or artificial blood including hemoglobin is non-particulate and therefore does not scatter light. Moreover, artificial hemoglobin is about to be approved by the United States Food and Drug Administration as a blood substitute and can carry oxygen necessary to prevent myocardial ischemia. Recently, the inventors demonstrated the viability of using artificial hemoglobin to reduce light scattering by blood in mouse myocardium coronary arteries (Villard J W, Feldman M D, Kim Jeehyun, Milner T O, and Freeman G L. Use of a blood substitute to determine instantaneous murine right ventricular thickening with optical coherence tomography. Circulation 2002, Volume 105: Pages 1843-1849, incorporated by reference herein). [0009] An OCT catheter to image coronary plaques has been built and is currently being tested by investigators. (Jang I K, Bouma B E, Hang O H, et al. Visualization of coronary atherosclerotic plaques in patients using optical coherence tomography: comparison with intravascular ultrasound. JACC 2002; 3 9: 604-609, incorporated by reference herein). The prototype catheter consists of a single light source and is able to image over a 360 degree arc of a coronary arterial lumen by rotating a shaft that spins the optical fiber. Because the rotating shaft is housed outside of the body, the spinning rod in the catheter must rotate with uniform angular velocity so that the light can be focused for equal intervals of time on each angular segment of the coronary artery. Mechanical drag in the rotating shaft can produce significant distortion and artifacts in recorded OCT images of the coronary artery. Unfortunately, because the catheter will always be forced to make several bends between the entry point in the femoral artery to the coronary artery (e.g., the 180 degree turn around the aortic arch), uneven mechanical drag will result in OCT image artifacts As the application of OCT is shifted from imaging gross anatomical structures of the coronary artery to its capability to image at the level of a single cell, non-uniform rotation of the single fiber OCT prototype will become an increasingly problematic source of distortion and image artifact. [0010] Essentially, current endoscope type single channel OCT systems suffer by non-constant rotating speed that forms irregular images of a vessel target. See U.S. Pat. No. 6,134,003, incorporated by reference herein. The approach of a rotary shaft to spin a single mode fiber is prone to produce artifacts. The catheter will always be forced to make several bends from its entry in the femoral artery, to the 180 degree turn around the aortic arch, to its final destination in the coronary artery. All these bends will cause uneven friction on the rotary shaft, and uneven time distribution of the light on the entire 360 degree arch of the coronary artery. As the application of OCT is shifted from gross anatomical structures of the coronary artery to its capability to image at higher resolutions (i.e., the level of a single cell), then non-uniform rotation of the single fiber OCT will become a greater source of artifact. [0011] The present invention overcomes this disadvantage of current single mode endoscope OCT by putting a rotating part at the end of the fiber probe. The rotating part is driven by biocompatible gas or liquid pumped externally. The rotating part is based on a miniature turbine, screw or water wheel, or nanotechnology. The single mode fiber itself remains stationary, but only a prism reflecting incident light to the target vessel wall will rotate at constant speed. [0012] The present invention pertains to a catheter imaging probe for a patient. The probe comprises a conduit through which energy is transmitted. The probe comprises a first portion through which the conduit extends. The probe comprises a second portion which rotates relative to the conduit to redirect the energy from the conduit. [0013] The present invention also pertains to a rotating tip assembly suitable for use with the inventive catheter imaging probe. The rotating tip assembly comprises generally an axle having a plurality of turbine-like members projecting generally radially outward from a central longitudinal axis of the axle, the axle further having a central longitudinal bore extending along the entire longitudinal axis of the axle. A distal end of the axle is beveled at an angle suitable to permit the reflection or refraction of optical energy at a predetermined angle away from the central longitudinal axis of the axle, then to gather light reflected back from the environment surrounding the catheter tip and transmit the same to the optical fiber. An outer housing having optically transparent properties is provided and is mounted on a distal end of a catheter body. A catheter end cap having a central longitudinal bore and a plurality of fluid flow ports passing through the catheter end cap and oriented co-axial with the longitudinal axis of the catheter end cap and the catheter body is provided. The catheter end cap is affixed within a distal end of the central longitudinal bore in the catheter body, and axle having the plurality of turbine-like members is concentrically and co-axially engaged within the central longitudinal bore of the catheter end cap and is rotatable therein. A second cap is provided which comprises generally concentrically aligned annular members, a first inner annular member defining a central longitudinal bore of the second cap and being in concentric spaced-apart relationship with a second outer cylindrical member so as to define an annular opening there between. The annular opening is maintained by spacer or rib members. The second outer cylindrical member has a plurality of fluid flow ports passing through a distal end surface thereof. BRIEF DESCRIPTION OF THE DRAWINGS [0014] FIG. 1 is a perspective view of the rotating tip assembly of the present invention depicting fluid flows there through and optical inputs. [0015] FIG. 2 is a perspective view of a first embodiment of a turbine member in accordance with the present invention. [0016] FIG. 3 is a perspective cut-away view of the rotating tip assembly of the present invention. [0017] FIG. 4A is an end elevational view of a housing cap for the rotating tip assembly of the present invention. [0018] FIG. 4B is a perspective end view of the housing cap for the rotating tip assembly of the present invention. [0019] FIG. 5A is a side end elevational view of the cap member for the rotating tip assembly of the present invention. [0020] FIG. 5B is a perspective view of the cap member for the rotating tip assembly of the present invention [0021] FIG. 6 is an end elevational view of an alternative embodiment of the housing cap in accordance with the present invention. [0022] FIG. 7 is a perspective view of an alternative embodiment of the turbine member in accordance with the present invention. [0023] FIG. 8 is a perspective view of an alternative embodiment of the second cap member in accordance with an embodiment of the present invention. [0024] FIG. 9 is a perspective view of an alternative embodiment of the rotating tip assembly in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0025] In the accompanying figures, like elements are identified by like reference numerals among the several preferred embodiments of the present invention. A rotating catheter tip assembly 10 comprises a housing 12 and a turbine 16 , as shown in FIG. 1 . The housing 12 includes a conduit 27 that extends through the housing 12 and turbine 16 , whereby the turbine 16 rotates relative to the conduit 27 to redirect energy from the conduit 27 . Preferably, conduit 27 is a radiation waveguide, and more preferably the radiation waveguide is an optical fiber. The rotating catheter tip assembly 10 rotates a reflecting material 17 , which then reflects energy emanating from the conduit 27 . The reflecting material 17 is coupled with a focusing element 19 to focus the energy from conduit 27 to a target. For purposes of this detailed description, it will be understood that light is redirected from an optical fiber and reflected light from a given in vivo target is then gathered and redirected back to the optical fiber through the focusing element 19 . The focusing element 19 may be any type of lens, GRIN lens, and the like suitable to focus optical energy. The focusing element 19 can be attached to the conduit, as to not rotate and alternatively, there is a space in between the focusing element 19 and the conduit 27 , whereby the focusing element 19 is attached to turbine 16 as to rotate thereby. [0026] The turbine 16 includes a center axle 22 and a plurality of vane members 18 , as shown in FIG. 2 . The center axle 22 includes a central longitudinal bore 26 , through which the conduit 27 extends. The center axle 22 includes a window opening 24 at the distal end, through which reflecting material 17 reflects energy emanating from the conduit 27 . The vane members 18 project radially outward from center axle 22 and provide a rotating torque to the center axle 22 when a flowing fluid (gas or liquid) flows against the vane members 16 , thereby causing the center axle 22 to rotate about the conduit 27 . Preferably, the vane members 16 can have a predetermined curvature along the longitudinal axis of the turbine 16 . The vane members 16 can be spiral shaped, or in any other configuration which permits rotation of the turbine 16 . Preferably, the turbine 16 is made from stainless steel, plastic tygon or Teflon. Alternatively, the turbine 16 includes knobs to support the axle 22 and allows the axle 22 to rotate without wobbling. [0027] The housing 12 includes a cylinder 32 , a housing cap 14 , and a cap member 20 , as shown in FIG. 3 . The cylinder 32 includes a central chamber 33 , a distal opening 29 , and outlet channels 30 . The central chamber 33 houses the turbine member 16 and includes an inflow and an outflow, which define a fluid flow pathway 48 . The inflow runs along the turbine member 16 , while the outflow runs along the outlet channels 30 . The housing cap 14 includes a plurality of fluid inlet ports 42 , a plurality of fluid outlet ports 44 , and a central opening 40 , as shown in FIGS. 4 a and 4 b . The fluid inlet ports 42 attach to fluid inlet tubes 41 , as shown in FIG. 1 . The fluid inlet tubes 41 are connected to a fluid source (not shown). The fluid inlet ports 42 pass through a generally central portion of the housing cap 14 , to transmit fluid to central chamber 33 . The fluid inlet ports 42 generally align with turbine member 16 . The fluid outlet ports 44 pass through a relatively peripheral portion of the housing 14 and align with the outlet channels 30 and outlet tubes 43 , as shown in FIG. 1 . The central opening 40 includes a concentric recessed seat 39 , as shown in FIG. 4 , in which the axle 22 sits and substantially rotates thereabout. Concentric recessed seat 39 is formed to permit the axle 22 to rotate without wobbling. The central opening 40 co-axially aligns with longitudinal bore 26 and permits conduit 27 to be passed there through, whereby the turbine member 16 is freely rotatable without rotate conduit 27 . The axle 22 is co-axially aligned to an opening 29 at a distal end of the housing 12 and opening 29 permits axle to rotate about an axis. Preferably the housing 12 is made from Teflon. Alternatively, the housing 12 includes a cover transparent to the energy and which encapsulates the turbine 16 , so that no fluid can escape from the housing except through the channels 30 . Preferably, the transparent cover is made from any biocompatible transparent plastic. Such plastic can include Polymethyl methacrylate (PMMA) or the like. [0028] The cap member 20 includes an inner annular member 28 , an outer annular member 27 , a plurality of spacer rib members 34 , and a plurality of spaces 35 , as shown in FIGS. 5 a and 5 b . The cap member 20 is concentrically mounted onto the distal end of the axle 22 through inner annular member 28 , as shown in FIG. 5 b . The inner annular member 28 permits axle 22 to freely rotate thereabout, without wobbling. The inner annular member 28 and outer annular member 27 are connected by spacer rib members 34 and are concentrically spaced apart. The spaces 35 between adjacent pairs of spacer rib members 34 provide outflow pathways for the fluid flow 48 to pass from the central chamber 33 to the distal end of housing 12 and then to outlet channels 30 . A plurality of fluid flow ports (not shown) may be provided in a distal surface of the cap member 20 and define a distal end of spaces 35 to channel fluid flow out of spaces 35 . [0029] At the distal end of the axle 22 , a reflecting material 17 (not shown) is attached to the center axle 22 at window 24 , as shown in FIG. 1 . The reflecting material redirects energy from the conduit 27 . The reflecting material preferably includes a prism or a mirror, which reflects energy from the conduit, the prism rotating with the center axle 22 . In one embodiment the energy is radiant energy. Preferably, a lens focuses energy onto the patient. The lens can be a microlens, GRIN lens, or optical fiber lines. The probe preferably includes a fluid source connected to the inlet tube. [0030] The fluid is provided to the inlet tubes 41 , as shown in FIG. 1 . The fluid is provided by a fluid source (not shown). Preferably, the fluid source is a pump. The pump can be any standard fluid pump, as known and recognized by those skilled in the art. Preferably, the fluid is chosen from a group consisting of oxygen, carbon dioxide, nitrogen, helium, saline, water, d5W or artificial blood such as Oxyglobin. Alternatively, any gas that can be dissolved into blood or tissue relatively easily can be used. Accordingly, a gas pump would used to provide fluid to the inlet tubes 41 . [0031] The preferred dimensions of the outer diameter of the housing 12 is 2 mm, the outer diameter of the turbine 16 is 1.4 mm, the outer diameter of the inlet tube 42 is 0.2 mm, the outer diameter of the outlet tube 44 is 0.2 mm. The speed can be 30 rotations per second. The turbine pitch can be 4 pitch/mm, while the speed of the gas flow can be 120 mm/sec and target flow rate is 3 mm 3 /sec. The above are all examples. The invention is not limited to these values. For instance, to obtain a finer image, the flow rate is lower and the time it takes to obtain an image is then longer. [0032] Alternatively, the turbine 16 includes wart to reflect energy coming through a radiation energy guide back to the radiation energy guide. The reflective wart can be any reflective material on the axle 22 . Preferably, the wart is block shape with a flat wall shape. The wart rotates with the turbine and the energy reflected by the wart indicates current angular position of the prism. The wart identifies one angular position of the rotating portion when the light hits and gets back form the wart. The wart may be a flat wall facing the radiation energy guide to reflect back. The wart can be molded into the axle, and flat wall can have a reflective material, such as a mirror placed on it to increase the reflection. The width of the wart is small compared to the circumference of axle 22 , so as to identify a given point, and is high enough to block the energy emitted from optical fiber, so it is reflected by wart. [0033] In operation, the assembly may be connected to a sample arm of a single mode fiber OCT. In the center of an OCT probe, the turbine 16 is connected to a prism. Gas or liquid flows through the inlet port 42 into the turbine chamber 32 . The turbine 16 is supported by positioning between the housing cap 14 and cap member 20 to maintain constant position during rotation. At the center of the turbine 16 , the central longitudinal bore 26 includes an optical fiber. During rotation of the turbine 16 , the optical fiber remains stationary. In spectral domain phase sensitive OCT, the reference reflecting surface is within the catheter. [0034] A probing light will be launched from the single mode optical fiber through a lens having a curvature to focus the light onto target tissue area. A rotating prism connected to the turbine reflects incoming light toward target tissue area on the vessel wall, enabling the imaging system to scan 360 degrees around an inner vessel wall at a constant speed. The reflected light from the target tissue returns to the fiber through the prism. A standard analysis of the light is then performed to obtain the image, as in U.S. Pat. No. 6,134,003, incorporated by reference herein. Gas or liquid gone through the turbine 16 exits the probe through an outlet tube 44 . The rotation direction and speed of the turbine are controlled by the pressure difference between inlet ports 42 and outlet ports 44 . Applying a gas or liquid through an inlet tube pressure is induced to the turbine which rotates; therefore, a prism put on the end of the turbine rotates as well. Finally, an imaging system can scan 360 degrees around the inner vessel wall at a constant speed. [0035] FIG. 6 depicts an alternative embodiment of a housing cap 14 , synonymously termed a catheter cap 14 , which is mountable on a distal open end of a catheter body (not shown) such that central flange 41 seats against the distal end of the catheter body (not shown). The fluid inlet openings 42 and fluid outlet openings 44 consist of channels which permit fluid flow to pass through the catheter cap 14 in the manner discussed above. Central opening 40 again accommodates passage of the optical fiber 27 therethrough and is co-axially aligned with the central bore of 26 of the turbine member 16 as depicted in FIG. 7 . The proximal and distal ends of the catheter cap 14 projects from the central flange 41 and are preferably mirror images of one another about the central flange 41 . [0036] An alternative embodiment of the turbine member 16 is illustrated in FIG. 7 . The principal difference between the first embodiment of the turbine member illustrated in FIGS. 1-5 is that there is a space in between the focusing element 19 and the conduit 27 . The space may be an air space or an optical gap providing for the optical energy permission to expand before being focused by the focusing element. In this embodiment, the focusing element 19 and the reflecting material 17 both rotate about the axis by the axle 22 , by being substantially connected to the axle by optical glue, or the like. Also, the curved or helical pitch of the turbine vanes 18 is greater than that depicted in FIGS. 1-5 , such that they subtend approximately a 90 degree arc about the circumference of the axle 22 . [0037] A second embodiment of a cap member 20 is depicted in FIG. 8 , and is synonymously termed second cap member 60 . The second cap member 60 includes a central opening 64 , a collection channel 65 and a plurality of outflow ports 66 . The central opening 64 is concentrically mounted onto the distal end of the axle 22 to permit axle 22 to rotate freely thereabout. The collection channel 65 is connected to the outflow ports 66 , to permit the outflow of fluid. The outflow ports are substantially aligned with the outflow ports 66 of the catheter cap 14 , to allow the outflow to return to the fluid source (not shown). Second cap member 60 is similar to second cap member 60 , in that it has an inner annular member 64 through which the axle 22 of turbine member, and an outer annular member 62 which is in concentrically spaced apart relationship therewith 16 passes except that after fluid flows through the spaces 35 it enters a return path by passing through outlet flow ports 66 which are provided about a peripheral portion of a distal surface of the second cap member 60 and enter the fluid outlet channels 30 in the housing 12 . [0038] FIG. 9 demonstrates the complete assembly 100 of the catheter cap 14 , second cap member 60 , with turbine member 16 therebetween. [0039] The present invention also pertains to a method for imaging a patient. The method comprises the steps of inserting a catheter into a patient, rotating a turbine 16 of the catheter relative to a conduit 27 , extending through the turbine 16 of the catheter, redirecting energy transmitted through the conduit 27 to the patient and receiving the energy reflected or backscattered to the turbine, and redirecting reflected energy to the conduit 27 . [0040] Preferably, the rotating step includes flowing fluid through an inlet tube 41 to the turbine 16 to turn an axle 22 of the turbine 16 . [0041] Preferably, the flowing step includes flowing the fluid against a plurality of vane members 18 which extend from a rotating center axle 22 of the turbine 16 to create a rotating torque on the center axle 22 to rotate about the conduit 27 that extends through the center axle 22 . The axle 22 preferably has reflecting material 17 attached to the distal end of the axle 22 , which redirects the energy from the conduit 27 . Preferably, the conduit 27 is an optical fiber. [0042] The reflecting material 17 preferably includes a prism or mirror which reflects light from the conduit, and includes rotating the prism with the axle as the axle is rotated by the flowing fluid. Preferably, the rotating step includes the step of rotating the center axle 22 that is supported by knobs of the cylinder of the turbine in which the center axle 22 is disposed. Preferably, flowing the fluid from the inlet tube 41 through a chamber 33 and removing the fluid flowing from the housing 12 through at least one outlet tube 43 . [0043] In the foregoing described embodiment of the invention, those of ordinary skill in the art will understand and appreciate that an assembly is described which provides a fluid drive mechanism for rotating a mirror about the central longitudinal axis of the assembly while transmitting optical energy from a co-axial optical fiber which is maintained stationary within the central axis of the assembly, such that light energy may be reflected or refracted perpendicular to the central longitudinal axis of the catheter and traverse a 360 degree arc. [0044] Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be described by the following claims.
The present invention relates to a rotating catheter tip for optical coherence tomography based on the use of an optical fiber that does not rotate, that is enclosed in a catheter, which has a tip rotates under the influence of a fluid drive system to redirect light from the fiber to a surrounding vessel and the light reflected or backscattered from the vessel back to the optical fiber.
Identify the most important claim in the given context and summarize it
[ "CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a continuation from U.S. patent application Ser.", "No. 12/911,541, filed Oct. 25, 2010, which is a continuation from U.S. patent application Ser.", "No. 11/551,684, filed Oct. 20, 2006, now U.S. Pat. No. 7,853,316, issued Dec. 14, 2010, which claims priority to U.S. Provisional Patent Application Ser.", "No. 60/728,481, filed Oct. 20, 2005, and which is a continuation-in-part “CIP”", "of U.S. patent application Ser.", "No. 10/548,982, which was filed Sep. 7, 2005 and granted a U.S. national stage filing date of May 2, 2006, now U.S. Pat. No. 7,711,413, issued May 4, 2010, which claims priority to PCT International Patent Application No. PCT/US2004/012773, filed Apr. 23, 2004 and which claims priority to U.S. Provisional Patent Application Ser.", "No. 60/466,215, filed Apr. 28, 2003, all of which are herein expressly incorporated by reference.", "BACKGROUND OF THE INVENTION [0002] The present invention relates to catheter probes based on the use of a fiber that does not rotate.", "More specifically, the present invention relates to optical coherence tomography based on the use of an optical fiber that does not rotate, which is enclosed in a catheter portion.", "[0003] Myocardial infarction or heart attack remains the leading cause of death in our society.", "Unfortunately, most of us can identify a family member or close friend that has suffered from a myocardial infarction.", "Until recently many investigators believed that coronary arteries critically blocked with atherosclerotic plaque that subsequently progressed to total occlusion was the primary mechanism for myocardial infarction.", "Recent evidence from many investigational studies, however, clearly indicates that most infarctions are due to sudden rupture of non-critically stenosed coronary arteries due to sudden plaque rupture.", "For example, Little et al.", "(Little, W C, Downes, T R, Applegate, R J. The underlying coronary lesion in myocardial infarction: implications for coronary angiography.", "Clin Cardiol 1991, 14: 868-874, incorporated by reference herein) observed that approximately 70% of patients suffering from an acute plaque rupture were initiated on plaques that were less than 50% occluded as revealed by previous coronary angiography.", "This and similar observations have been confirmed by other investigators (Nissen, S. Coronary angiography and intravascular ultrasound.", "Am J Cardiol 2001, 87 (suppl): 15A -20 A, incorporated by reference herein).", "[0004] The development of technologies to identify these unstable plaques holds the potential to decrease substantially the incidence of acute coronary syndromes that often lead to premature death.", "Unfortunately, no methods are currently available to the cardiologist that may be applied to specify which coronary plaques are vulnerable and thus prone to rupture.", "Although treadmill testing has been used for decades to identify patients at greater cardiovascular risk, this approach does not have the specificity to differentiate between stable and vulnerable plaques that are prone to rupture and frequently result in myocardial infarction.", "Inasmuch as a great deal of information exists regarding the pathology of unstable plaques (determined at autopsy) technologies based upon identifying the well described pathologic appearance of the vulnerable plaque offers a promising long term strategy to solve this problem.", "[0005] The unstable plaque was first identified and characterized by pathologists in the early 1980's.", "Davis and coworkers noted that with the reconstruction of serial histological sections in patients with acute myocardial infarctions associated with death, a rupture or fissuring of athermanous plaque was evident (Davis M J, Thomas A C. Plaque fissuring: the cause of acute myocardial infarction, sudden death, and crescendo angina.", "Br Heart J 1985;", "53: 3 63-37 3, incorporated by reference herein).", "Ulcerated plaques were further characterized as having a thin fibrous cap, increased macrophages with decreased smooth muscle cells and an increased lipid core when compared to non-ulcerated atherosclerotic plaques in human aortas (Davis M J, Richardson E D, Woolf N. Katz O R, Mann J. Risk of thrombosis in human atherosclerotic plaques: role of extracellular lipid, macrophage, and smooth muscle cell content, incorporated by reference herein).", "Furthermore, no correlation in size of lipid pool and percent stenosis was observed when imaging by coronary angiography.", "In fact, most cardiologists agree that unstable plaques progress to more stenotic yet stable plaques through progression via rupture with the formation of a mural thrombus and plaque remodeling, but without complete luminal occlusion (Topol E J, Rabbaic R. Strategies to achieve coronary arterial plaque stabilization.", "Cardiovasc Res 1999;", "41: 402-417, incorporated by reference herein).", "Neovascularization with intra-plaque hemorrhage may also play a role in this progression from small lesions, i.e., those less than about 50% occluded, to larger significant plaques.", "Yet, if the unique features of unstable plaque could be recognized by the cardiologist and then stabilized, a dramatic decrease may be realized in both acute myocardial infarction and unstable angina syndromes, and in the sudden progression of coronary artery disease.", "SUMMARY OF THE INVENTION [0006] The present invention uses depth-resolved light reflection or Optical Coherence Tomography (OCT) to identify the pathological features that have been identifie3d in the vulnerable plaque.", "In OCT, light from a broad band light source or tunable laser source is split by an optical fiber splitter with one fiber directing light to the vessel wall and the other fiber directing light to a moving reference mirror.", "The distal end of the optical fiber is interfaced with a catheter for interrogation of the coronary artery during a heart catheterization procedure.", "The reflected light from the plaque is recombined with the signal from the reference mirror forming interference fringes (measured by an photovoltaic detector) allowing precise depth-resolved imaging of the plaque on a micron scale.", "[0007] OCT uses a superluminescent diode source or tunable laser source emitting a 1300 nm wave length, with a 50-250 nm band width (distribution of wave length) to make in situ tomographic images with axial resolution of 2-20 μm and tissue penetration of 2-3 mm.", "OCT has the potential to image tissues at the level of a single cell.", "In fact, the inventors have recently utilized broader band width optical sources so that axial resolution is improved to 4 um or less.", "With such resolution, OCT can be applied to visualize intimal caps, their thickness, and details of structure including fissures, the size and extent of the underlying lipid pool and the presence of inflammatory cells.", "Moreover, near infrared light sources used in OCT instrumentation can penetrate into heavily calcified tissue regions characteristic of advanced coronary artery disease.", "With cellular resolution, application of OCT may be used to identify other details of the vulnerable plaque such as infiltration of monocytes and macrophages.", "In short, application of OCT can provide detailed images of a pathologic specimen without cutting or disturbing the tissue.", "[0008] One concern regarding application of this technology to image atherosclerotic plaques within the arterial lumen is the strong scattering of light due to the presence of red blood cells.", "Once a catheter system is positioned in a coronary artery, the blood flow between the OCT optical fiber and artery can obscure light penetration into the vessel wall.", "One proposed solution is the use of saline flushes.", "Saline use is limited in duration, however, since myocardial ischemia eventually occurs in the distal myocardium.", "The inventors have proposed the use of artificial blood substitutes in the place of saline.", "Artificial hemoglobin or artificial blood including hemoglobin is non-particulate and therefore does not scatter light.", "Moreover, artificial hemoglobin is about to be approved by the United States Food and Drug Administration as a blood substitute and can carry oxygen necessary to prevent myocardial ischemia.", "Recently, the inventors demonstrated the viability of using artificial hemoglobin to reduce light scattering by blood in mouse myocardium coronary arteries (Villard J W, Feldman M D, Kim Jeehyun, Milner T O, and Freeman G L. Use of a blood substitute to determine instantaneous murine right ventricular thickening with optical coherence tomography.", "Circulation 2002, Volume 105: Pages 1843-1849, incorporated by reference herein).", "[0009] An OCT catheter to image coronary plaques has been built and is currently being tested by investigators.", "(Jang I K, Bouma B E, Hang O H, et al.", "Visualization of coronary atherosclerotic plaques in patients using optical coherence tomography: comparison with intravascular ultrasound.", "JACC 2002;", "3 9: 604-609, incorporated by reference herein).", "The prototype catheter consists of a single light source and is able to image over a 360 degree arc of a coronary arterial lumen by rotating a shaft that spins the optical fiber.", "Because the rotating shaft is housed outside of the body, the spinning rod in the catheter must rotate with uniform angular velocity so that the light can be focused for equal intervals of time on each angular segment of the coronary artery.", "Mechanical drag in the rotating shaft can produce significant distortion and artifacts in recorded OCT images of the coronary artery.", "Unfortunately, because the catheter will always be forced to make several bends between the entry point in the femoral artery to the coronary artery (e.g., the 180 degree turn around the aortic arch), uneven mechanical drag will result in OCT image artifacts As the application of OCT is shifted from imaging gross anatomical structures of the coronary artery to its capability to image at the level of a single cell, non-uniform rotation of the single fiber OCT prototype will become an increasingly problematic source of distortion and image artifact.", "[0010] Essentially, current endoscope type single channel OCT systems suffer by non-constant rotating speed that forms irregular images of a vessel target.", "See U.S. Pat. No. 6,134,003, incorporated by reference herein.", "The approach of a rotary shaft to spin a single mode fiber is prone to produce artifacts.", "The catheter will always be forced to make several bends from its entry in the femoral artery, to the 180 degree turn around the aortic arch, to its final destination in the coronary artery.", "All these bends will cause uneven friction on the rotary shaft, and uneven time distribution of the light on the entire 360 degree arch of the coronary artery.", "As the application of OCT is shifted from gross anatomical structures of the coronary artery to its capability to image at higher resolutions (i.e., the level of a single cell), then non-uniform rotation of the single fiber OCT will become a greater source of artifact.", "[0011] The present invention overcomes this disadvantage of current single mode endoscope OCT by putting a rotating part at the end of the fiber probe.", "The rotating part is driven by biocompatible gas or liquid pumped externally.", "The rotating part is based on a miniature turbine, screw or water wheel, or nanotechnology.", "The single mode fiber itself remains stationary, but only a prism reflecting incident light to the target vessel wall will rotate at constant speed.", "[0012] The present invention pertains to a catheter imaging probe for a patient.", "The probe comprises a conduit through which energy is transmitted.", "The probe comprises a first portion through which the conduit extends.", "The probe comprises a second portion which rotates relative to the conduit to redirect the energy from the conduit.", "[0013] The present invention also pertains to a rotating tip assembly suitable for use with the inventive catheter imaging probe.", "The rotating tip assembly comprises generally an axle having a plurality of turbine-like members projecting generally radially outward from a central longitudinal axis of the axle, the axle further having a central longitudinal bore extending along the entire longitudinal axis of the axle.", "A distal end of the axle is beveled at an angle suitable to permit the reflection or refraction of optical energy at a predetermined angle away from the central longitudinal axis of the axle, then to gather light reflected back from the environment surrounding the catheter tip and transmit the same to the optical fiber.", "An outer housing having optically transparent properties is provided and is mounted on a distal end of a catheter body.", "A catheter end cap having a central longitudinal bore and a plurality of fluid flow ports passing through the catheter end cap and oriented co-axial with the longitudinal axis of the catheter end cap and the catheter body is provided.", "The catheter end cap is affixed within a distal end of the central longitudinal bore in the catheter body, and axle having the plurality of turbine-like members is concentrically and co-axially engaged within the central longitudinal bore of the catheter end cap and is rotatable therein.", "A second cap is provided which comprises generally concentrically aligned annular members, a first inner annular member defining a central longitudinal bore of the second cap and being in concentric spaced-apart relationship with a second outer cylindrical member so as to define an annular opening there between.", "The annular opening is maintained by spacer or rib members.", "The second outer cylindrical member has a plurality of fluid flow ports passing through a distal end surface thereof.", "BRIEF DESCRIPTION OF THE DRAWINGS [0014] FIG. 1 is a perspective view of the rotating tip assembly of the present invention depicting fluid flows there through and optical inputs.", "[0015] FIG. 2 is a perspective view of a first embodiment of a turbine member in accordance with the present invention.", "[0016] FIG. 3 is a perspective cut-away view of the rotating tip assembly of the present invention.", "[0017] FIG. 4A is an end elevational view of a housing cap for the rotating tip assembly of the present invention.", "[0018] FIG. 4B is a perspective end view of the housing cap for the rotating tip assembly of the present invention.", "[0019] FIG. 5A is a side end elevational view of the cap member for the rotating tip assembly of the present invention.", "[0020] FIG. 5B is a perspective view of the cap member for the rotating tip assembly of the present invention [0021] FIG. 6 is an end elevational view of an alternative embodiment of the housing cap in accordance with the present invention.", "[0022] FIG. 7 is a perspective view of an alternative embodiment of the turbine member in accordance with the present invention.", "[0023] FIG. 8 is a perspective view of an alternative embodiment of the second cap member in accordance with an embodiment of the present invention.", "[0024] FIG. 9 is a perspective view of an alternative embodiment of the rotating tip assembly in accordance with the present invention.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0025] In the accompanying figures, like elements are identified by like reference numerals among the several preferred embodiments of the present invention.", "A rotating catheter tip assembly 10 comprises a housing 12 and a turbine 16 , as shown in FIG. 1 .", "The housing 12 includes a conduit 27 that extends through the housing 12 and turbine 16 , whereby the turbine 16 rotates relative to the conduit 27 to redirect energy from the conduit 27 .", "Preferably, conduit 27 is a radiation waveguide, and more preferably the radiation waveguide is an optical fiber.", "The rotating catheter tip assembly 10 rotates a reflecting material 17 , which then reflects energy emanating from the conduit 27 .", "The reflecting material 17 is coupled with a focusing element 19 to focus the energy from conduit 27 to a target.", "For purposes of this detailed description, it will be understood that light is redirected from an optical fiber and reflected light from a given in vivo target is then gathered and redirected back to the optical fiber through the focusing element 19 .", "The focusing element 19 may be any type of lens, GRIN lens, and the like suitable to focus optical energy.", "The focusing element 19 can be attached to the conduit, as to not rotate and alternatively, there is a space in between the focusing element 19 and the conduit 27 , whereby the focusing element 19 is attached to turbine 16 as to rotate thereby.", "[0026] The turbine 16 includes a center axle 22 and a plurality of vane members 18 , as shown in FIG. 2 .", "The center axle 22 includes a central longitudinal bore 26 , through which the conduit 27 extends.", "The center axle 22 includes a window opening 24 at the distal end, through which reflecting material 17 reflects energy emanating from the conduit 27 .", "The vane members 18 project radially outward from center axle 22 and provide a rotating torque to the center axle 22 when a flowing fluid (gas or liquid) flows against the vane members 16 , thereby causing the center axle 22 to rotate about the conduit 27 .", "Preferably, the vane members 16 can have a predetermined curvature along the longitudinal axis of the turbine 16 .", "The vane members 16 can be spiral shaped, or in any other configuration which permits rotation of the turbine 16 .", "Preferably, the turbine 16 is made from stainless steel, plastic tygon or Teflon.", "Alternatively, the turbine 16 includes knobs to support the axle 22 and allows the axle 22 to rotate without wobbling.", "[0027] The housing 12 includes a cylinder 32 , a housing cap 14 , and a cap member 20 , as shown in FIG. 3 .", "The cylinder 32 includes a central chamber 33 , a distal opening 29 , and outlet channels 30 .", "The central chamber 33 houses the turbine member 16 and includes an inflow and an outflow, which define a fluid flow pathway 48 .", "The inflow runs along the turbine member 16 , while the outflow runs along the outlet channels 30 .", "The housing cap 14 includes a plurality of fluid inlet ports 42 , a plurality of fluid outlet ports 44 , and a central opening 40 , as shown in FIGS. 4 a and 4 b .", "The fluid inlet ports 42 attach to fluid inlet tubes 41 , as shown in FIG. 1 .", "The fluid inlet tubes 41 are connected to a fluid source (not shown).", "The fluid inlet ports 42 pass through a generally central portion of the housing cap 14 , to transmit fluid to central chamber 33 .", "The fluid inlet ports 42 generally align with turbine member 16 .", "The fluid outlet ports 44 pass through a relatively peripheral portion of the housing 14 and align with the outlet channels 30 and outlet tubes 43 , as shown in FIG. 1 .", "The central opening 40 includes a concentric recessed seat 39 , as shown in FIG. 4 , in which the axle 22 sits and substantially rotates thereabout.", "Concentric recessed seat 39 is formed to permit the axle 22 to rotate without wobbling.", "The central opening 40 co-axially aligns with longitudinal bore 26 and permits conduit 27 to be passed there through, whereby the turbine member 16 is freely rotatable without rotate conduit 27 .", "The axle 22 is co-axially aligned to an opening 29 at a distal end of the housing 12 and opening 29 permits axle to rotate about an axis.", "Preferably the housing 12 is made from Teflon.", "Alternatively, the housing 12 includes a cover transparent to the energy and which encapsulates the turbine 16 , so that no fluid can escape from the housing except through the channels 30 .", "Preferably, the transparent cover is made from any biocompatible transparent plastic.", "Such plastic can include Polymethyl methacrylate (PMMA) or the like.", "[0028] The cap member 20 includes an inner annular member 28 , an outer annular member 27 , a plurality of spacer rib members 34 , and a plurality of spaces 35 , as shown in FIGS. 5 a and 5 b .", "The cap member 20 is concentrically mounted onto the distal end of the axle 22 through inner annular member 28 , as shown in FIG. 5 b .", "The inner annular member 28 permits axle 22 to freely rotate thereabout, without wobbling.", "The inner annular member 28 and outer annular member 27 are connected by spacer rib members 34 and are concentrically spaced apart.", "The spaces 35 between adjacent pairs of spacer rib members 34 provide outflow pathways for the fluid flow 48 to pass from the central chamber 33 to the distal end of housing 12 and then to outlet channels 30 .", "A plurality of fluid flow ports (not shown) may be provided in a distal surface of the cap member 20 and define a distal end of spaces 35 to channel fluid flow out of spaces 35 .", "[0029] At the distal end of the axle 22 , a reflecting material 17 (not shown) is attached to the center axle 22 at window 24 , as shown in FIG. 1 .", "The reflecting material redirects energy from the conduit 27 .", "The reflecting material preferably includes a prism or a mirror, which reflects energy from the conduit, the prism rotating with the center axle 22 .", "In one embodiment the energy is radiant energy.", "Preferably, a lens focuses energy onto the patient.", "The lens can be a microlens, GRIN lens, or optical fiber lines.", "The probe preferably includes a fluid source connected to the inlet tube.", "[0030] The fluid is provided to the inlet tubes 41 , as shown in FIG. 1 .", "The fluid is provided by a fluid source (not shown).", "Preferably, the fluid source is a pump.", "The pump can be any standard fluid pump, as known and recognized by those skilled in the art.", "Preferably, the fluid is chosen from a group consisting of oxygen, carbon dioxide, nitrogen, helium, saline, water, d5W or artificial blood such as Oxyglobin.", "Alternatively, any gas that can be dissolved into blood or tissue relatively easily can be used.", "Accordingly, a gas pump would used to provide fluid to the inlet tubes 41 .", "[0031] The preferred dimensions of the outer diameter of the housing 12 is 2 mm, the outer diameter of the turbine 16 is 1.4 mm, the outer diameter of the inlet tube 42 is 0.2 mm, the outer diameter of the outlet tube 44 is 0.2 mm.", "The speed can be 30 rotations per second.", "The turbine pitch can be 4 pitch/mm, while the speed of the gas flow can be 120 mm/sec and target flow rate is 3 mm 3 /sec.", "The above are all examples.", "The invention is not limited to these values.", "For instance, to obtain a finer image, the flow rate is lower and the time it takes to obtain an image is then longer.", "[0032] Alternatively, the turbine 16 includes wart to reflect energy coming through a radiation energy guide back to the radiation energy guide.", "The reflective wart can be any reflective material on the axle 22 .", "Preferably, the wart is block shape with a flat wall shape.", "The wart rotates with the turbine and the energy reflected by the wart indicates current angular position of the prism.", "The wart identifies one angular position of the rotating portion when the light hits and gets back form the wart.", "The wart may be a flat wall facing the radiation energy guide to reflect back.", "The wart can be molded into the axle, and flat wall can have a reflective material, such as a mirror placed on it to increase the reflection.", "The width of the wart is small compared to the circumference of axle 22 , so as to identify a given point, and is high enough to block the energy emitted from optical fiber, so it is reflected by wart.", "[0033] In operation, the assembly may be connected to a sample arm of a single mode fiber OCT.", "In the center of an OCT probe, the turbine 16 is connected to a prism.", "Gas or liquid flows through the inlet port 42 into the turbine chamber 32 .", "The turbine 16 is supported by positioning between the housing cap 14 and cap member 20 to maintain constant position during rotation.", "At the center of the turbine 16 , the central longitudinal bore 26 includes an optical fiber.", "During rotation of the turbine 16 , the optical fiber remains stationary.", "In spectral domain phase sensitive OCT, the reference reflecting surface is within the catheter.", "[0034] A probing light will be launched from the single mode optical fiber through a lens having a curvature to focus the light onto target tissue area.", "A rotating prism connected to the turbine reflects incoming light toward target tissue area on the vessel wall, enabling the imaging system to scan 360 degrees around an inner vessel wall at a constant speed.", "The reflected light from the target tissue returns to the fiber through the prism.", "A standard analysis of the light is then performed to obtain the image, as in U.S. Pat. No. 6,134,003, incorporated by reference herein.", "Gas or liquid gone through the turbine 16 exits the probe through an outlet tube 44 .", "The rotation direction and speed of the turbine are controlled by the pressure difference between inlet ports 42 and outlet ports 44 .", "Applying a gas or liquid through an inlet tube pressure is induced to the turbine which rotates;", "therefore, a prism put on the end of the turbine rotates as well.", "Finally, an imaging system can scan 360 degrees around the inner vessel wall at a constant speed.", "[0035] FIG. 6 depicts an alternative embodiment of a housing cap 14 , synonymously termed a catheter cap 14 , which is mountable on a distal open end of a catheter body (not shown) such that central flange 41 seats against the distal end of the catheter body (not shown).", "The fluid inlet openings 42 and fluid outlet openings 44 consist of channels which permit fluid flow to pass through the catheter cap 14 in the manner discussed above.", "Central opening 40 again accommodates passage of the optical fiber 27 therethrough and is co-axially aligned with the central bore of 26 of the turbine member 16 as depicted in FIG. 7 .", "The proximal and distal ends of the catheter cap 14 projects from the central flange 41 and are preferably mirror images of one another about the central flange 41 .", "[0036] An alternative embodiment of the turbine member 16 is illustrated in FIG. 7 .", "The principal difference between the first embodiment of the turbine member illustrated in FIGS. 1-5 is that there is a space in between the focusing element 19 and the conduit 27 .", "The space may be an air space or an optical gap providing for the optical energy permission to expand before being focused by the focusing element.", "In this embodiment, the focusing element 19 and the reflecting material 17 both rotate about the axis by the axle 22 , by being substantially connected to the axle by optical glue, or the like.", "Also, the curved or helical pitch of the turbine vanes 18 is greater than that depicted in FIGS. 1-5 , such that they subtend approximately a 90 degree arc about the circumference of the axle 22 .", "[0037] A second embodiment of a cap member 20 is depicted in FIG. 8 , and is synonymously termed second cap member 60 .", "The second cap member 60 includes a central opening 64 , a collection channel 65 and a plurality of outflow ports 66 .", "The central opening 64 is concentrically mounted onto the distal end of the axle 22 to permit axle 22 to rotate freely thereabout.", "The collection channel 65 is connected to the outflow ports 66 , to permit the outflow of fluid.", "The outflow ports are substantially aligned with the outflow ports 66 of the catheter cap 14 , to allow the outflow to return to the fluid source (not shown).", "Second cap member 60 is similar to second cap member 60 , in that it has an inner annular member 64 through which the axle 22 of turbine member, and an outer annular member 62 which is in concentrically spaced apart relationship therewith 16 passes except that after fluid flows through the spaces 35 it enters a return path by passing through outlet flow ports 66 which are provided about a peripheral portion of a distal surface of the second cap member 60 and enter the fluid outlet channels 30 in the housing 12 .", "[0038] FIG. 9 demonstrates the complete assembly 100 of the catheter cap 14 , second cap member 60 , with turbine member 16 therebetween.", "[0039] The present invention also pertains to a method for imaging a patient.", "The method comprises the steps of inserting a catheter into a patient, rotating a turbine 16 of the catheter relative to a conduit 27 , extending through the turbine 16 of the catheter, redirecting energy transmitted through the conduit 27 to the patient and receiving the energy reflected or backscattered to the turbine, and redirecting reflected energy to the conduit 27 .", "[0040] Preferably, the rotating step includes flowing fluid through an inlet tube 41 to the turbine 16 to turn an axle 22 of the turbine 16 .", "[0041] Preferably, the flowing step includes flowing the fluid against a plurality of vane members 18 which extend from a rotating center axle 22 of the turbine 16 to create a rotating torque on the center axle 22 to rotate about the conduit 27 that extends through the center axle 22 .", "The axle 22 preferably has reflecting material 17 attached to the distal end of the axle 22 , which redirects the energy from the conduit 27 .", "Preferably, the conduit 27 is an optical fiber.", "[0042] The reflecting material 17 preferably includes a prism or mirror which reflects light from the conduit, and includes rotating the prism with the axle as the axle is rotated by the flowing fluid.", "Preferably, the rotating step includes the step of rotating the center axle 22 that is supported by knobs of the cylinder of the turbine in which the center axle 22 is disposed.", "Preferably, flowing the fluid from the inlet tube 41 through a chamber 33 and removing the fluid flowing from the housing 12 through at least one outlet tube 43 .", "[0043] In the foregoing described embodiment of the invention, those of ordinary skill in the art will understand and appreciate that an assembly is described which provides a fluid drive mechanism for rotating a mirror about the central longitudinal axis of the assembly while transmitting optical energy from a co-axial optical fiber which is maintained stationary within the central axis of the assembly, such that light energy may be reflected or refracted perpendicular to the central longitudinal axis of the catheter and traverse a 360 degree arc.", "[0044] Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be described by the following claims." ]
BACKGROUND OF THE INVENTION The invention relates to a process for the production of a composite camshaft and an apparatus suitable for use in the production process. A known process for the production of composite camshafts is disclosed in German Application No. DE-A1-3209980 wherein cam elements and bearing elements produced by sintering are fixed on a shaft by means of small pins or tubes arranged in radial bore holes. After fixing the elements in place, the camshaft is sintered at a predetermined temperature so as to allow the cam elements and bearing elements to become integrally bonded with the shaft. The process for making the radial bore holes in the shaft, the angular position of which has to be very exact, is very laborious and requires a number of mechanical operations including an alignment of the parts during the drilling operation and also during the subsequent fixing in position operation, which is disadvantageous for economical reasons. The object of the present invention is the development of a process for the production of a composite camshaft which makes possible a simple alignment and fixing in position of the cam elements and bearing elements on the shaft in an efficient operation. The present invention is also drawn to an apparatus for carrying out the process. SUMMARY OF THE INVENTION The foregoing objects are achieved by way of the process of the present invention for the production of a composite camshaft having a plurality of cam elements and a plurality of bearing elements mounted on a shaft at a desired location and a desired orientation comprising providing an elongated shaft having a longitudinal axis and an outer circumferential surface configuration, providing a plurality of cam elements and bearing elements wherein each of the cam elements and bearing elements are provided with an internal bore having a size and configuration substantially similar to the outer circumferential configuration of the shaft, positioning the plurality of cam elements and the plurality of bearing elements successively on the shaft, locating a first of one of the plurality of cam elements and the plurality of bearing elements at a desired location along the longitudinal axis of the shaft, orienting the first of one of the plurality of cam elements and the plurality of bearing elements at a desired orientation on the outer circumferential surface of the shaft with respect to the longitudinal axis thereof, fixing the first of one of the plurality of cam elements and the plurality of bearing elements on the shaft, and repeating the locating, orienting and fixing steps until all of the plurality of cam elements and bearing elements are secured on each shaft. The apparatus for carrying out the process comprises first motor means for rotatably supporting a shaft for rotation about a longitudinal axis of the shaft, gripping means mounted proximate to the shaft for selectively holding the cam elements at desired locations along the axis of the shaft, securing means associated with the gripping means for securing the selectively held cam elements to the shaft, second motor means for displacing the gripping means and the securing means along the axis of the shaft, and control means for selectively actuating the first and second motor means for locating and orienting the cam elements on the shaft. BRIEF DESCRIPTION OF THE DRAWING The single figure shows a diagrammatic representation of an apparatus for the automatic positioning and fixing in position of cam elements on a camshaft in accordance with the process of the present invention. DETAILED DESCRIPTION The apparatus has a receiving device 10 for the camshaft 1, which consists of a preferably hollow shaft 2 and cam elements 3 and bearing elements 4 arranged thereupon. The receiving device 10 has a chucking fixture 12 which is rotatably by first motor means in the form of a rotary drive 11 and, at the other end, a tailstock with a center 13, for keeping a shaft 2 rotatably supported about axis 16. On the chucking fixture 12 there is arranged an angle of rotation measuring device 14, which is effectively connected to a microprocessor 15. Parallel to the axis of rotation 16 there is arranged a longitudinal guide 17, on which a gripping device 19 is longitudinally displaceable by means of a second motor means or drive 18. A displacement measuring device 20 is effectively connected to the microprocessor 15. The first and second drives 11 and 18 are likewise effectively connected to the microprocessor 15. A securing means 21 in the form of a welding or soldering device is arranged to be longitudinally displaceably together with the gripping device 19. The securing means 21 is designed for the application of at least three weld or solder points evenly distributed round the circumference on one end face of the cam elements 3. The welding or soldering device may also be arranged longitudinally displaceably on a second guide if desired, which requires a further drive and displacement measuring device. The process for the production of the camshaft is as follows. The cam elements 3, and if desired also the bearing elements 4, are pushed onto the shaft 2 in the desired number and sequence, where they are aligned in one direction alongside one another at one end of the shaft. The cam elements, preferably made of a hard casting, each have a bore hole which has a slight play with respect to the preferably smooth shaft, which is achieved by prior mechanical working, for example by grinding. The shaft 2, provided with the cam elements 3 and bearing elements 4 threaded on, is located in the receiving device 10 and microprocessor 15 is actuated which causes the first cam element 3 located near the free end of the shaft to be seized by the gripping device 19 and brought into the desired position on the shaft by longitudinal displacement thereof by means of the gripping device and drive 18. Thereafter, by turning of the shaft 2 by means of the rotary drive 11 the desired orientation of the cam element is accomplished. As the welding or soldering device 21 is likewise brought into the operational position at the same time as the longitudinal displacement of the gripping device 19, the corresponding weld or solder points can be applied, for example by the extension of preferably three weding or soldering arms, to one end face of the cam element 3 for the fixing of the cam element in the correct position. Thus, all cam elements successively or, if two having the same circumferential direction are alongside each other, two cam elements at once, are brought into the specified position and fixed there by means of a tack connection. Once all cam elements have been fixed in position, the firm connection of the cam elements 3 to the shaft 2 is established by a circumferential weld or solder connection on at least one end face of each cam element 3. This is preferably performed in a separate welding or soldering device or by means of a welding or soldering device additional arranged in the previously described apparatus. It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modification of form, size, arrangement of pafts and details of operation. The invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims.
A process for the production of composite camshafts comprises the selective positioning of a plurality of cam elements on a camshaft and orienting the cam elements at a desired location with respect to the central axis of the shaft and thereafter securing the cam elements in place on the shaft.
Identify and summarize the most critical features from the given passage.
[ "BACKGROUND OF THE INVENTION The invention relates to a process for the production of a composite camshaft and an apparatus suitable for use in the production process.", "A known process for the production of composite camshafts is disclosed in German Application No. DE-A1-3209980 wherein cam elements and bearing elements produced by sintering are fixed on a shaft by means of small pins or tubes arranged in radial bore holes.", "After fixing the elements in place, the camshaft is sintered at a predetermined temperature so as to allow the cam elements and bearing elements to become integrally bonded with the shaft.", "The process for making the radial bore holes in the shaft, the angular position of which has to be very exact, is very laborious and requires a number of mechanical operations including an alignment of the parts during the drilling operation and also during the subsequent fixing in position operation, which is disadvantageous for economical reasons.", "The object of the present invention is the development of a process for the production of a composite camshaft which makes possible a simple alignment and fixing in position of the cam elements and bearing elements on the shaft in an efficient operation.", "The present invention is also drawn to an apparatus for carrying out the process.", "SUMMARY OF THE INVENTION The foregoing objects are achieved by way of the process of the present invention for the production of a composite camshaft having a plurality of cam elements and a plurality of bearing elements mounted on a shaft at a desired location and a desired orientation comprising providing an elongated shaft having a longitudinal axis and an outer circumferential surface configuration, providing a plurality of cam elements and bearing elements wherein each of the cam elements and bearing elements are provided with an internal bore having a size and configuration substantially similar to the outer circumferential configuration of the shaft, positioning the plurality of cam elements and the plurality of bearing elements successively on the shaft, locating a first of one of the plurality of cam elements and the plurality of bearing elements at a desired location along the longitudinal axis of the shaft, orienting the first of one of the plurality of cam elements and the plurality of bearing elements at a desired orientation on the outer circumferential surface of the shaft with respect to the longitudinal axis thereof, fixing the first of one of the plurality of cam elements and the plurality of bearing elements on the shaft, and repeating the locating, orienting and fixing steps until all of the plurality of cam elements and bearing elements are secured on each shaft.", "The apparatus for carrying out the process comprises first motor means for rotatably supporting a shaft for rotation about a longitudinal axis of the shaft, gripping means mounted proximate to the shaft for selectively holding the cam elements at desired locations along the axis of the shaft, securing means associated with the gripping means for securing the selectively held cam elements to the shaft, second motor means for displacing the gripping means and the securing means along the axis of the shaft, and control means for selectively actuating the first and second motor means for locating and orienting the cam elements on the shaft.", "BRIEF DESCRIPTION OF THE DRAWING The single figure shows a diagrammatic representation of an apparatus for the automatic positioning and fixing in position of cam elements on a camshaft in accordance with the process of the present invention.", "DETAILED DESCRIPTION The apparatus has a receiving device 10 for the camshaft 1, which consists of a preferably hollow shaft 2 and cam elements 3 and bearing elements 4 arranged thereupon.", "The receiving device 10 has a chucking fixture 12 which is rotatably by first motor means in the form of a rotary drive 11 and, at the other end, a tailstock with a center 13, for keeping a shaft 2 rotatably supported about axis 16.", "On the chucking fixture 12 there is arranged an angle of rotation measuring device 14, which is effectively connected to a microprocessor 15.", "Parallel to the axis of rotation 16 there is arranged a longitudinal guide 17, on which a gripping device 19 is longitudinally displaceable by means of a second motor means or drive 18.", "A displacement measuring device 20 is effectively connected to the microprocessor 15.", "The first and second drives 11 and 18 are likewise effectively connected to the microprocessor 15.", "A securing means 21 in the form of a welding or soldering device is arranged to be longitudinally displaceably together with the gripping device 19.", "The securing means 21 is designed for the application of at least three weld or solder points evenly distributed round the circumference on one end face of the cam elements 3.", "The welding or soldering device may also be arranged longitudinally displaceably on a second guide if desired, which requires a further drive and displacement measuring device.", "The process for the production of the camshaft is as follows.", "The cam elements 3, and if desired also the bearing elements 4, are pushed onto the shaft 2 in the desired number and sequence, where they are aligned in one direction alongside one another at one end of the shaft.", "The cam elements, preferably made of a hard casting, each have a bore hole which has a slight play with respect to the preferably smooth shaft, which is achieved by prior mechanical working, for example by grinding.", "The shaft 2, provided with the cam elements 3 and bearing elements 4 threaded on, is located in the receiving device 10 and microprocessor 15 is actuated which causes the first cam element 3 located near the free end of the shaft to be seized by the gripping device 19 and brought into the desired position on the shaft by longitudinal displacement thereof by means of the gripping device and drive 18.", "Thereafter, by turning of the shaft 2 by means of the rotary drive 11 the desired orientation of the cam element is accomplished.", "As the welding or soldering device 21 is likewise brought into the operational position at the same time as the longitudinal displacement of the gripping device 19, the corresponding weld or solder points can be applied, for example by the extension of preferably three weding or soldering arms, to one end face of the cam element 3 for the fixing of the cam element in the correct position.", "Thus, all cam elements successively or, if two having the same circumferential direction are alongside each other, two cam elements at once, are brought into the specified position and fixed there by means of a tack connection.", "Once all cam elements have been fixed in position, the firm connection of the cam elements 3 to the shaft 2 is established by a circumferential weld or solder connection on at least one end face of each cam element 3.", "This is preferably performed in a separate welding or soldering device or by means of a welding or soldering device additional arranged in the previously described apparatus.", "It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modification of form, size, arrangement of pafts and details of operation.", "The invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims." ]
RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §120 of U.S. application Ser. No. 12/437,746, entitled “SYSTEM AND METHOD FOR PREDICTING COOLING PERFORMANCE OF ARRANGEMENTS OF EQUIPMENT IN A DATA CENTER,” filed on May 8, 2009, and issued on Aug. 21, 2012, as U.S. Pat. No. 8,249,825, which is herein incorporated by reference in its entirety. BACKGROUND 1. Field of the Invention At least one embodiment in accordance with the present invention relates generally to systems and methods for data center management and design, and more specifically, to systems and methods for predicting cooling performance of arrangements of equipment in a data center, including improper clusters of equipment in a data center. 2. Discussion of Related Art In response to the increasing demands of information-based economies, information technology networks continue to proliferate across the globe. One manifestation of this growth is the centralized network data center. A centralized network data center typically consists of various information technology equipment, collocated in a structure that provides network connectivity, electrical power and cooling capacity. Often the equipment is housed of specialized enclosures termed “racks” which integrate these connectivity, power and cooling elements. In some data center configurations, these rows are organized into hot and cold aisles to decrease the cost associated with cooling the information technology equipment. These characteristics make data centers a cost effective way to deliver the computing power required by many software applications. Various processes and software applications, such as the InfrastruXure® Central product available from American Power Conversion Corporation of West Kingston, R.I., have been developed to aid data center personnel in designing and maintaining efficient and effective data centers configurations. These tools often guide data center personnel through activities such as designing the data center structure, positioning equipment within the data center prior to installation and repositioning equipment after construction and installation are complete. Thus, conventional tool sets provide data center personnel with a standardized and predictable design methodology. SUMMARY OF THE INVENTION A first aspect of the invention is directed to a computer-implemented method for evaluating equipment in an improper cluster in a data center, the equipment including a plurality of equipment racks, and at least one rack-based cooling provider. The method includes receiving data regarding each of the plurality of equipment racks and the at least one cooling provider, the data including a layout of the improper cluster of equipment racks and the at least one cooling provider, storing the received data, identifying at least one gap in the layout, determining cooling performance of at least one of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap, and displaying the layout of the data center, wherein the layout includes an indication of the cooling performance of the at least one of the plurality of equipment racks. In the method, determining cooling performance of the at least one of the plurality of equipment racks may include determining capture index for the at least one of the plurality of equipment racks, and the method may further include determining capture index for each of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap. In the method, determining capture index may include determining airflow through the at least one gap, and determining airflow may include determining airflow out of an aisle of the improper cluster through the at least one gap, and determining airflow into the aisle through the at least one gap. Further, determining cooling performance of the at least one of the plurality of equipment racks may include determining a value for capture index for the at least one of the plurality of equipment racks with each gap in the layout modeled as a blank panel. The method may further include determining a corrector value based on characteristics of the at least one gap, and applying the corrector value to the value for capture index for the at least one of the plurality of equipment racks. The method may also include positioning the equipment in the data center in accordance with the layout. Another aspect of the invention is directed to a system for evaluating equipment in an improper cluster in a data center, the equipment including a plurality of equipment racks, and at least one rack-based cooling provider. The system includes an interface, and a controller configured to receive data regarding each of the plurality of equipment racks and the at least one cooling provider, the data including a layout of the improper cluster of equipment racks and the at least one cooling provider, store the received data in the system, identify at least one gap in the layout, and determine cooling performance of at least one of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap. The system may further include a display coupled to the controller, and the controller may be further configured to display the layout of the data center, wherein the layout includes an indication of the cooling performance of the at least one of the plurality of equipment racks. The controller may be further configured to determine capture index for the at least one of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap. In the system, the controller may be configured to determine airflow out of an aisle of the improper cluster through the at least one gap, and determine airflow into the aisle through the at least one gap. The controller may be further configured to determine a value for capture index for the at least one of the plurality of equipment racks with each gap in the layout modeled as a blank panel. Further, the controller may be configured to determine a corrector value based on characteristics of the at least one gap, and apply the corrector value to the value for capture index for the at least one of the plurality of equipment racks. Another aspect of the invention is directed to a computer readable medium having stored thereon sequences of instruction including instructions that will cause a processor to receive data regarding a layout of an improper cluster of equipment racks and at least one cooling provider, store the received data, identify at least one gap in the layout, and determine cooling performance of at least one of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap. The sequences of instruction may further include instructions that will cause the processor to display the layout of the data center on a display associated with the processor, wherein the layout includes an indication of the cooling performance of the at least one of the plurality of equipment racks. The medium may also include instructions that will cause the processor to determine capture index for the at least one of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap. The sequences of instruction may further include instructions that will cause the processor to determine airflow through the at least one gap, including airflow out of an aisle of the improper cluster through the at least one gap, and determine airflow into the aisle through the at least one gap. The sequences of instruction may also include instructions that will cause the processor to determine a value for capture index for the at least one of the plurality of equipment racks with each gap in the layout modeled as a blank panel, and the sequences of instruction may further include instructions that will cause the processor to determine a corrector value based on characteristics of the at least one gap, and apply the corrector value to the value for capture index for the at least one of the plurality of equipment racks. BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings: FIG. 1 shows an example computer system with which various aspects in accord with the present invention may be implemented; FIG. 2 illustrates an example distributed system including an embodiment; FIG. 3 shows a layout of an improper cluster of data equipment racks and coolers; and FIG. 4 shows a flowchart of a process for determining cooling characteristics in accordance with one embodiment. DETAILED DESCRIPTION At least some embodiments in accordance with the present invention relate to systems and processes through which a user may design data center configurations. These systems may facilitate this design activity by allowing the user to create models of data center configurations from which performance metrics may be determined. Both the systems and the user may employ these performance metrics to determine alternative data center configurations that meet various design objectives. Further, in at least one embodiment, a system will provide an initial layout of data center equipment and conduct a cooling analysis on the layout in real time. As described in U.S. patent application Ser. No. 12/019,109, titled “System and Method for Evaluating Equipment Rack Cooling”, filed Jan. 24, 2008 (referred to herein as “the '109 Application”), and in U.S. patent application Ser. No. 11/342,300, titled “Methods and Systems for Managing Facility Power and Cooling” filed Jan. 27, 2006 (referred to herein as “the '300 application”), both of which are assigned to the assignee of the present application, and both of which are hereby incorporated herein by reference in their entirety, typical equipment racks in modern data centers draw cooling air in the front of the rack and exhaust air out the rear of the rack. The equipment racks, and in-row coolers are typically arranged in rows in an alternating front/back arrangement creating alternating hot and cool aisles in a data center with the front of each row of racks facing the cool aisle and the rear of each row of racks facing the hot aisle. Adjacent rows of equipment racks separated by a cool aisle may be referred to as a cool aisle cluster, and adjacent rows of equipment racks separated by a hot aisle may be referred to as a hot aisle cluster. As readily apparent to one of ordinary skill in the art, a row of equipment racks may be part of one hot aisle cluster and one cool aisle cluster. In descriptions and claims herein, equipment in racks, or the racks themselves, may be referred to as cooling consumers, and in-row cooling units and/or computer room air conditioners (CRACs) may be referred to as cooling providers. In the referenced applications, tools are provided for analyzing the cooling performance of a cluster of racks in a data center. In these tools, multiple analyses may be performed on different layouts to attempt to optimize the cooling performance of the data center. In typical prior methods and systems for designing and analyzing the layout of clusters in a data center, the methods and systems are either limited for use with simple clusters having two equal-length rows and no gaps or openings in the rows, or if not limited to simple clusters, involve the use of complex algorithms that typically cannot be performed in real-time. In data centers, there are many equipment groupings that have unequal row length or contain gaps and are not proper clusters easily analyzed by prior techniques. For at least one embodiment, an improper cluster is defined herein as including a two-row grouping of racks, and potentially coolers, around a common cool or hot aisle in which there are gaps in the rows or unequal-length rows. A single row may constitute an improper cluster. A continuous break between equipment in a row greater than three feet may constitute a break in the row and the row may be divided into multiple proper and improper clusters, or considered to be one improper cluster. In at least one embodiment, a method is provided for predicting the cooling performance of an improper cluster in a data center in real-time. The method may be incorporated in a system having capabilities for predicting the cooling performance of proper clusters and for performing other design and analysis functions of equipment in a data center. The aspects disclosed herein in accordance with the present invention, are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. These aspects are capable of assuming other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. In particular, acts, elements and features discussed in connection with any one or more embodiments are not intended to be excluded from a similar role in any other embodiments. For example, according to one embodiment of the present invention, a computer system is configured to perform any of the functions described herein, including but not limited to, configuring, modeling and presenting information regarding specific data center configurations. Further, computer systems in embodiments of the data center may be used to automatically measure environmental parameters in a data center, and control equipment, such as chillers or coolers to optimize performance. Moreover, the systems described herein may be configured to include or exclude any of the functions discussed herein. Thus the invention is not limited to a specific function or set of functions. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use herein of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Computer System Various aspects and functions described herein in accordance with the present invention may be implemented as hardware or software on one or more computer systems. There are many examples of computer systems currently in use. These examples include, among others, network appliances, personal computers, workstations, mainframes, networked clients, servers, media servers, application servers, database servers and web servers. Other examples of computer systems may include mobile computing devices, such as cellular phones and personal digital assistants, and network equipment, such as load balancers, routers and switches. Further, aspects in accordance with the present invention may be located on a single computer system or may be distributed among a plurality of computer systems connected to one or more communications networks. For example, various aspects and functions may be distributed among one or more computer systems configured to provide a service to one or more client computers, or to perform an overall task as part of a distributed system. Additionally, aspects may be performed on a client-server or multi-tier system that includes components distributed among one or more server systems that perform various functions. Thus, the invention is not limited to executing on any particular system or group of systems. Further, aspects may be implemented in software, hardware or firmware, or any combination thereof. Thus, aspects in accordance with the present invention may be implemented within methods, acts, systems, system elements and components using a variety of hardware and software configurations, and the invention is not limited to any particular distributed architecture, network, or communication protocol. FIG. 1 shows a block diagram of a distributed computer system 100 , in which various aspects and functions in accord with the present invention may be practiced. Distributed computer system 100 may include one more computer systems. For example, as illustrated, distributed computer system 100 includes computer systems 102 , 104 and 106 . As shown, computer systems 102 , 104 and 106 are interconnected by, and may exchange data through, communication network 108 . Network 108 may include any communication network through which computer systems may exchange data. To exchange data using network 108 , computer systems 102 , 104 and 106 and network 108 may use various methods, protocols and standards, including, among others, token ring, ethernet, wireless ethernet, Bluetooth, TCP/IP, UDP, Http, FTP, SNMP, SMS, MMS, SS7, Json, Soap, and Corba. To ensure data transfer is secure, computer systems 102 , 104 and 106 may transmit data via network 108 using a variety of security measures including TSL, SSL or VPN among other security techniques. While distributed computer system 100 illustrates three networked computer systems, distributed computer system 100 may include any number of computer systems and computing devices, networked using any medium and communication protocol. Various aspects and functions in accordance with the present invention may be implemented as specialized hardware or software executing in one or more computer systems including computer system 102 shown in FIG. 1 . As depicted, computer system 102 includes processor 110 , memory 112 , bus 114 , interface 116 and storage 118 . Processor 110 may perform a series of instructions that result in manipulated data. Processor 110 may be a commercially available processor such as an Intel Pentium, Motorola PowerPC, SGI MIPS, Sun UltraSPARC, or Hewlett-Packard PA-RISC processor, but may be any type of processor or controller as many other processors and controllers are available. Processor 110 is connected to other system elements, including one or more memory devices 112 , by bus 114 . Memory 112 may be used for storing programs and data during operation of computer system 102 . Thus, memory 112 may be a relatively high performance, volatile, random access memory such as a dynamic random access memory (DRAM) or static memory (SRAM). However, memory 112 may include any device for storing data, such as a disk drive or other non-volatile storage device. Various embodiments in accordance with the present invention may organize memory 112 into particularized and, in some cases, unique structures to perform the aspects and functions disclosed herein. Components of computer system 102 may be coupled by an interconnection element such as bus 114 . Bus 114 may include one or more physical busses, for example, busses between components that are integrated within a same machine, but may include any communication coupling between system elements including specialized or standard computing bus technologies such as IDE, SCSI, PCI and InfiniBand. Thus, bus 114 enables communications, for example, data and instructions, to be exchanged between system components of computer system 102 . Computer system 102 also includes one or more interface devices 116 such as input devices, output devices and combination input/output devices. Interface devices may receive input or provide output. More particularly, output devices may render information for external presentation. Input devices may accept information from external sources. Examples of interface devices include keyboards, mouse devices, trackballs, microphones, touch screens, printing devices, display screens, speakers, network interface cards, etc. Interface devices allow computer system 102 to exchange information and communicate with external entities, such as users and other systems. Storage system 118 may include a computer readable and writeable nonvolatile storage medium in which instructions are stored that define a program to be executed by the processor. Storage system 118 also may include information that is recorded, on or in, the medium, and this information may be processed by the program. More specifically, the information may be stored in one or more data structures specifically configured to conserve storage space or increase data exchange performance. The instructions may be persistently stored as encoded signals, and the instructions may cause a processor to perform any of the functions described herein. The medium may, for example, be optical disk, magnetic disk or flash memory, among others. In operation, the processor or some other controller may cause data to be read from the nonvolatile recording medium into another memory, such as memory 112 , that allows for faster access to the information by the processor than does the storage medium included in storage system 118 . The memory may be located in storage system 118 or in memory 112 , however, processor 110 may manipulate the data within the memory 112 , and then copies the data to the medium associated with storage system 118 after processing is completed. A variety of components may manage data movement between the medium and integrated circuit memory element and the invention is not limited thereto. Further, the invention is not limited to a particular memory system or storage system. Although computer system 102 is shown by way of example as one type of computer system upon which various aspects and functions in accordance with the present invention may be practiced, aspects of the invention are not limited to being implemented on the computer system as shown in FIG. 1 . Various aspects and functions in accord with the present invention may be practiced on one or more computers having a different architectures or components than that shown in FIG. 1 . For instance, computer system 102 may include specially-programmed, special-purpose hardware, such as for example, an application-specific integrated circuit (ASIC) tailored to perform a particular operation disclosed herein. While another embodiment may perform the same function using several general-purpose computing devices running MAC OS System X with Motorola PowerPC processors and several specialized computing devices running proprietary hardware and operating systems. Computer system 102 may be a computer system including an operating system that manages at least a portion of the hardware elements included in computer system 102 . Usually, a processor or controller, such as processor 110 , executes an operating system which may be, for example, a Windows-based operating system, such as, Windows NT, Windows 2000 (Windows ME), Windows XP or Windows Vista operating systems, available from the Microsoft Corporation, a MAC OS System X operating system available from Apple Computer, one of many Linux-based operating system distributions, for example, the Enterprise Linux operating system available from Red Hat Inc., a Solaris operating system available from Sun Microsystems, or a UNIX operating system available from various sources. Many other operating systems may be used, and embodiments are not limited to any particular implementation. The processor and operating system together define a computer platform for which application programs in high-level programming languages may be written. These component applications may be executable, intermediate, for example, C−, bytecode or interpreted code which communicates over a communication network, for example, the Internet, using a communication protocol, for example, TCP/IP. Similarly, aspects in accord with the present invention may be implemented using an object-oriented programming language, such as .Net, SmallTalk, Java, C++, Ada, or C# (C-Sharp). Other object-oriented programming languages may also be used. Alternatively, functional, scripting, or logical programming languages may be used. Additionally, various aspects and functions in accordance with the present invention may be implemented in a non-programmed environment, for example, documents created in HTML, XML or other format that, when viewed in a window of a browser program, render aspects of a graphical-user interface or perform other functions. Further, various embodiments in accord with the present invention may be implemented as programmed or non-programmed elements, or any combination thereof. For example, a web page may be implemented using HTML while a data object called from within the web page may be written in C++. Thus, the invention is not limited to a specific programming language and any suitable programming language could also be used. Further, in at least one embodiment, the tool may be implemented using VBA Excel. A computer system included within an embodiment may perform additional functions outside the scope of the invention. For instance, aspects of the system may be implemented using an existing commercial product, such as, for example, Database Management Systems such as SQL Server available from Microsoft of Seattle Wash., Oracle Database from Oracle of Redwood Shores, Calif., and MySQL from MySQL AB of Uppsala, Sweden or integration software such as Web Sphere middleware from IBM of Armonk, N.Y. However, a computer system running, for example, SQL Server may be able to support both aspects in accord with the present invention and databases for sundry applications not within the scope of the invention. Example System Architecture FIG. 2 presents a context diagram including physical and logical elements of distributed system 200 . As shown, distributed system 200 is specially configured in accordance with the present invention. The system structure and content recited with regard to FIG. 2 is for exemplary purposes only and is not intended to limit the invention to the specific structure shown in FIG. 2 . As will be apparent to one of ordinary skill in the art, many variant system structures can be architected without deviating from the scope of the present invention. The particular arrangement presented in FIG. 2 was chosen to promote clarity. Information may flow between the elements, components and subsystems depicted in FIG. 2 using any technique. Such techniques include, for example, passing the information over the network via TCP/IP, passing the information between modules in memory and passing the information by writing to a file, database, or some other non-volatile storage device. Other techniques and protocols may be used without departing from the scope of the invention. Referring to FIG. 2 , system 200 includes user 202 , interface 204 , data center design and management system 206 , communications network 208 and data center database 210 . System 200 may allow user 202 , such as a data center architect or other data center personnel, to interact with interface 204 to create or modify a model of one or more data center configurations. According to one embodiment, interface 204 may include aspects of the floor editor and the rack editor as disclosed in Patent Cooperation Treaty Application No. PCT/US08/63675, entitled METHODS AND SYSTEMS FOR MANAGING FACILITY POWER AND COOLING, filed on May 15, 2008, which is incorporated herein by reference in its entirety and is hereinafter referred to as PCT/US08/63675. In other embodiments, interface 204 may be implemented with specialized facilities that enable user 202 to design, in a drag and drop fashion, a model that includes a representation of the physical layout of a data center or any subset thereof. This layout may include representations of data center structural components as well as data center equipment. The features of interface 204 , as may be found in various embodiments in accordance with the present invention, are discussed further below. In at least one embodiment, information regarding a data center is entered into system 200 through the interface, and assessments and recommendations for the data center are provided to the user. Further, in at least one embodiment, optimization processes may be performed to optimize cooling performance and energy usage of the data center. As shown in FIG. 2 , data center design and management system 206 presents data design interface 204 to user 202 . According to one embodiment, data center design and management system 206 may include the data center design and management system as disclosed in PCT/US08/63675. In this embodiment, design interface 204 may incorporate functionality of the input module, the display module and the builder module included in PCT/US08/63675 and may use the database module to store and retrieve data. As illustrated, data center design and management system 206 may exchange information with data center database 210 via network 208 . This information may include any information required to support the features and functions of data center design and management system 206 . For example, in one embodiment, data center database 210 may include at least some portion of the data stored in the data center equipment database described in PCT/US08/63675. In another embodiment, this information may include any information required to support interface 204 , such as, among other data, the physical layout of one or more data center model configurations, the production and distribution characteristics of the cooling providers included in the model configurations, the consumption characteristics of the cooling consumers in the model configurations, and a listing of equipment racks and cooling providers to be included in a cluster. In one embodiment, data center database 210 may store types of cooling providers, the amount of cool air provided by each type of cooling provider, and a temperature of cool air provided by the cooling provider. Thus, for example, data center database 210 includes records of a particular type of CRAC unit that is rated to deliver airflow at the rate of 5,600 cfm at a temperature of 68 degrees Fahrenheit. In addition, the data center database 210 may store one or more cooling metrics, such as inlet and outlet temperatures of the CRACs and inlet and outlet temperatures of one or more equipment racks. The temperatures may be periodically measured and input into the system, or in other embodiments, the temperatures may be continuously monitored using devices coupled to the system 200 . Data center database 210 may take the form of any logical construction capable of storing information on a computer readable medium including, among other structures, flat files, indexed files, hierarchical databases, relational databases or object oriented databases. The data may be modeled using unique and foreign key relationships and indexes. The unique and foreign key relationships and indexes may be established between the various fields and tables to ensure both data integrity and data interchange performance. The computer systems shown in FIG. 2 , which include data center design and management system 206 , network 208 and data center equipment database 210 , each may include one or more computer systems. As discussed above with regard to FIG. 1 , computer systems may have one or more processors or controllers, memory and interface devices. The particular configuration of system 200 depicted in FIG. 2 is used for illustration purposes only and embodiments of the invention may be practiced in other contexts. Thus, embodiments of the invention are not limited to a specific number of users or systems. In at least one embodiment, which will now be described, a tool is provided that predicts cooling performance for an improper hot aisle cluster in real time and displays results of the prediction along with a model of the improper cluster. FIG. 3 shows a model of an improper cluster of racks 300 . The improper cluster includes two rows of racks A and B separated by a hot aisle 302 . Each row includes racks R and coolers C. Row A includes 6 racks and 3 coolers and Row B includes 4 racks and 1 cooler. Row B also includes two gaps 304 and 306 . In one embodiment, the racks are standard nineteen inch equipment racks having an overall width of 24 inches and the coolers have a width of 12 inches. However, embodiments of the invention may be used with racks and coolers of other sizes. Gap 304 is approximately two feet wide and gap 306 , representing a difference in lengths of the Rows A and B, is approximately 4 feet wide. As shown in FIG. 3 , in accordance with some embodiments, the results of the prediction of cooling performance may be displayed directly on the racks in the model. In FIG. 3 , the results are shown as capture index (in percentage) on each of the racks in the model. In embodiments of the invention, different performance metrics can be used to evaluate the cooling performance of an improper cluster. In one embodiment, the performance metric is capture index. Capture index, and methods of determining capture index are described in greater detail in the '109 and '300 applications referenced above. The cold-aisle capture index for a rack is defined in at least some embodiments as the fraction of air ingested by the rack which originates from local cooling resources (e.g., perforated floor tiles or local coolers). The hot-aisle capture index is defined as the fraction of air exhausted by a rack which is captured by local extracts (e.g., local coolers or return vents). CI therefore varies between 0 and 100% with better cooling performance generally indicated by greater CI values. In a cold-aisle analysis, high CI's ensure that the bulk of the air ingested by a rack comes from local cooling resources rather than being drawn from the room environment or from air which may have already been heated by electronics equipment. In this case, rack inlet temperatures will closely track the perforated-tile airflow temperatures and, assuming these temperatures are within the desired range, acceptable cooling will be achieved. In a hot-aisle analysis, high CI's ensure that rack exhaust is captured locally and there is little heating of the surrounding room environment. While good (high) CI values typically imply good cooling performance; low CI values do not necessarily imply unacceptable cooling performance. For example, in a rack in a raised-floor environment which draws most of its airflow from the surrounding room environment rather than from the perforated tiles, the rack's cold-aisle CI will be low; however, if the surrounding room environment is sufficiently cool, the rack's inlet temperature may still be acceptable. In this case, the rack's cooling needs are met by the external room environment rather than perforated tiles within the rack's cluster. If this process is repeated many times across the data center, facility cooling will be complex and may be unpredictable. High CI values lead to inherently scalable cluster layouts and more predictable room environments. In one embodiment, a tool operable on one or more computer systems described above determines capture index for racks of an improper cluster. In doing so, the improper cluster is first analyzed as a proper cluster, with all gaps and any row-length mismatches filled with blanking panels (or “dummy” racks with zero airflow). The capture index is determined for each of the racks in the proper cluster using any of a number of techniques for determining the CI, including the algebraic, neural network and PDA-CFD techniques described in the '109 and '300 applications referenced above. Once the CI is determined for the proper cluster, a corrector model is applied to the results to correct for the negative effects created by gaps in the improper cluster. Gaps in the rows of an improper cluster provide an opening to allow air to escape from the aisle between the two rows in a cluster having a negative effect on the capture index. The corrector model determines the percentage of reduction of the CI for each rack in the improper cluster. The final CI for a rack i in an improper cluster can be expressed as follows using equation (1): CI i gap =CI i blank ·(1−Corrector i )  Equation (1) where, CI i blank is the “benchmark” CI value for rack i when all the gaps and row length mismatches in the cluster are replaced by blanking panels. Corrector i is the percentage reduction (expressed as a decimal value) of the CI of rack i. In equations discussed herein, rack locations are designated as A i and B j . The designation A or B indicates which row the rack is contained in and the subscript i or j indicates the slot in the row containing the rack, which may be counted from left or right. For example, in the cluster of FIG. 3 , Row A includes 6 racks and 3 coolers for a total of 9 objects or 30 6-inch slots and Row B includes 4 racks, one cooler and two gaps for a totally of 7 objects or 30 6-inch slots. The CI corrector is related to the distance between the rack of interest and all the gaps in the improper cluster where each 6-inch “slot” (in an open “gap section” like 304 or 306 of FIG. 3 ) is typically considered one gap. In one embodiment, the percentage reduction of the CI value of a certain rack at location A i can be adequately represented as follows: ⁢ Equation ⁢ ⁢ ( 2 ) Corrector Ai = X · ∑ j all ⁢ ⁢ gaps ⁢ ⁢ in ⁢ ⁢ row ⁢ ⁢ A ⁢ ⁢ ⅇ - Y · Δ ⁢ ⁢ x ⁡ ( i , j ) + Z · ∑ j all ⁢ ⁢ gaps ⁢ ⁢ in ⁢ ⁢ row ⁢ ⁢ B ⁢ ⁢ ⅇ - Y · Δ ⁢ ⁢ x ⁡ ( i , j ) ∑ j all ⁢ ⁢ objects ⁢ ⁢ in ⁢ ⁢ row ⁢ ⁢ A ⁢ ⁢ ⅇ - Y · Δ ⁢ ⁢ x ⁡ ( i , j ) + Z · ∑ j all ⁢ ⁢ objects ⁢ ⁢ in ⁢ ⁢ row ⁢ ⁢ B ⁢ ⁢ ⅇ - Y · Δ ⁢ ⁢ x ⁡ ( i , j ) where, Corrector Ai is the percentage reduction (expressed as a decimal value) of the CI of rack i in Row A X, Y, and Z are empirical constants Δx(i,j) is the horizontal distance between locations (slots) i and j. In equation (2), the numerator is equal to zero when there are no gaps and hence the Corrector Ai becomes zero. In this case, the cluster is a proper cluster and no correction is needed. The closer a gap is to a rack, the larger the Corrector for that rack and hence the lower the CI of the rack. The empirical constants X, Y and Z can be determined by comparing the calculations for a large number of layouts to corresponding “benchmark” cases typically created by CFD simulation. The constants in the model are then adjusted to give the best overall agreement with the benchmark cases based on various metrics including CI. The Corrector described herein can be applied to any type of improper cluster, which might include hot aisle improper clusters with row-based coolers and cold aisle improper clusters with row-based coolers and/or perforated tiles. In one example, for hot aisle improper clusters with row-based coolers, constants X and Y are fixed for all cluster configurations, but constant Z varies with aisle width as shown in the table below. For a single-row improper cluster, Z is 2. TABLE 1 Constants vs. Aisle Width for Hot Aisle Clusters with Row-Based Coolers Hot Aisle Width (ft) Constant 3 4 5 6 X 1 1 1 1 Y 0.073 0.073 0.073 0.073 Z 3 2.33 1.67 1 In one example, for cold aisle improper clusters with row-based coolers, constants X and Y are fixed for all cluster configurations, but the constant Z varies with aisle width as shown in the table below. For a single row improper cluster, Z is 2. TABLE 2 Constants vs. Aisle Width for Cold Aisle Clusters with Row-Based Coolers Cold Aisle Width (ft) Constant 4 6 X 1 1 Y 0.123 0.123 Z 3 1 In one example, for cold aisle improper clusters with perforated tiles, constants X and Y are fixed for all cluster configurations, but constant Z varies with aisle width as shown in the table below. For a single row improper cluster, Z is 0.18. TABLE 3 Constants vs. Aisle Width for Cold Aisle Clusters with Perforated Tiles Cold Aisle Width (ft) Constant 4 6 X 1 1 Y 2.8 2.8 Z 0.1 0.05 In one example, for cold aisle improper clusters with both row-based coolers and perforated tiles, the calculation of constant X can be expressed as follows using equation (3): X=α·X PT +(1−α)· X IR   Equation (3) where, X PT is the constant X used in the cold-aisle-cluster-with-perforated-tiles applications for the same cold aisle width; X IR is the constant X used in the cold aisle cluster-with-row-based-coolers applications for the same cold aisle width; and α is the fraction of supply airflow delivered by the perforated tiles. Constants Y and Z are be determined in a similar manner. It is noted that the effect of the presence of gaps on cooling performance is greater for layouts with row-based coolers than for raised floor applications due to the strong horizontal airflow patterns associated with row-based coolers. FIG. 4 provides a flow chart of a process 400 for determining the CI for equipment racks of an improper cluster using the corrector model described above in accordance with one embodiment. First at stage 402 of the process 400 , information regarding the layout for the improper cluster is loaded into the tool. The information may include power consumption values for each of the racks, cooling capacities of each of the coolers and location of the racks and coolers in the layout. At least some of the information may have previously been stored in a database contained in a computer system implementing the tool transmitted to the computer system via a network or loaded into the system by a user. At stage 404 , gaps are identified in the improper cluster, and the gaps (including mismatches at the end of a row) are covered in the layout with blanking panels or replaced with racks having no airflow. The CI for each rack in the improper cluster is then determined (stage 406 ) using one of a number of techniques as discussed above. As part of stage 406 , the Corrector for each rack is determined and applied to the CI. At stage 408 , the model is then displayed (and may be printed) with the corrected CI for each of the racks. At stage 410 , the process ends. In some embodiments, the displayed model may provide additional indications for out of tolerance CI values, such as warning labels or through the use of color codes. Further, in some embodiments, when an out of tolerance condition is indicated, a user may be prompted to rearrange the racks to find a more satisfactory solution. In another embodiment, a tool for determining CI for equipment racks in improper hot aisle clusters utilizes an embedded algebraic model. This embedded algebraic model may be included within existing algebraic models (or similar models) for proper clusters or may be implemented as a stand alone tool. One example of an algebraic model with which the embedded algebraic model may be used is described in the '109 and '300 applications referenced above. In the embedded algebraic model of one embodiment, airflow which passes through gaps is explicitly estimated in order to account for the unfavorable effects of gaps on the CI of each rack. In general, there are two types of airflows through any given gap: an inflow, Q gap in , and an outflow, Q gap out . Both “in” and “out” airflows may be simultaneously present in the same gap. The model of airflows used in at least one embodiment of the tool need not have a direct, accurate physical interpretation for the tool to be effective. In other words, if the “in” term computed by the tool is, for example, 375 cfm; it does not mean that the actual inflow through the gap must be 375 cfm for the tool to be effective. Rather, the use of the “in” and “out” flow terms allow for more degrees of freedom in the tool with which the tool may be “tuned.” The inflow, Q gap in , is determined by the cooler airflow rate as well as the distance between all the coolers and the gap. It has been found that the airflow rate which comes in through a gap i in row A into a hot aisle can be adequately represented as shown in Equation (4) below: ( Q Ai ) gap ⁢ ⁢ in = ∑ all ⁢ ⁢ j ≠ i all ⁢ ⁢ coolers ⁢ ⁢ j ⁢ ⁢ in ⁢ ⁢ Row ⁢ ⁢ A ⁢ ⁢ ( Q Aj ) cap ⁢ ⁢ self · X 1 · ⅇ - Y 1 · Δ ⁢ ⁢ x ⁡ ( i , j ) + X 3 · ∑ all ⁢ ⁢ j ≠ i all ⁢ ⁢ coolers ⁢ ⁢ j ⁢ ⁢ in ⁢ ⁢ Row ⁢ ⁢ B ⁢ ⁢ ( Q Bj ) cap ⁢ ⁢ self · X 1 · ⅇ - Y 1 · Δ ⁢ ⁢ x ⁡ ( i , j ) Equation ⁢ ⁢ ( 4 ) where, (Q Ai ) gap in is the airflow rate that comes in through the gap at location A i (Q Aj ) cap self is the airflow rate captured by the cooler at location A j (Q Bj ) cap self is the airflow rate captured by the cooler at location B j Δx(i,j) is the horizontal distance between locations (slots) i and j X 1 and Y 1 are empirical constants and X 3 is the empirical “coupling” constant accounting for effects from the opposite row. Similarly, the outflow, Q gap out can be determined by the rack airflow rate as well as the distance between all the racks and the gap. It has been found that the airflow rate which leaves the hot aisle through a gap i in row A can be adequately represented as: ( Q Ai ) gap ⁢ ⁢ out = ∑ all ⁢ ⁢ j ≠ i all ⁢ ⁢ rock ⁢ ⁢ j ⁢ ⁢ in ⁢ ⁢ Row ⁢ ⁢ A ⁢ ⁢ ( Q Aj ) sup ⁢ ⁢ self · X 2 · ⅇ - Y 2 · Δ ⁢ ⁢ x ⁡ ( i , j ) + Y 3 · ∑ all ⁢ ⁢ j ≠ i all ⁢ ⁢ rock ⁢ ⁢ j ⁢ ⁢ in ⁢ ⁢ Row ⁢ ⁢ B ⁢ ⁢ ( Q Bj ) sup ⁢ ⁢ self · X 2 · ⅇ - Y 2 · Δ ⁢ ⁢ x ⁡ ( i , j ) Equation ⁢ ⁢ ( 5 ) where, (Q Ai ) gap out is the airflow rate that leaves through the gap at location A i (Q Aj ) sup self is the airflow rate supplied by the rack at location A j (Q Bj ) sup self is the airflow rate supplied by the rack at location B j Δx(i,j) is the horizontal distance between locations (slots) i and j X 2 and Y 2 are empirical constants and Y 3 is the empirical “coupling” constant accounting for effects from the opposite row. The constants are, again, determined by comparing the calculations for a large number of layouts to corresponding “benchmark” cases typically created by CFD simulation. The constants in the model are then adjusted to give the best overall agreement with the benchmark cases based on various metrics including CI. When calculating the net airflow that can be supplied to a particular location A i using the current hot-aisle algebraic calculator, the tool accounts for the airflow which escapes the hot aisle through all the gaps. To accomplish this, two extra terms are subtracted from the equation to calculate the (Q Aj ) cap net (from the '109 Application referenced above) one for row A and one for Row B as shown by Equation (6) below: ( Q Ai ) cap ⁢ ⁢ net = ( Q Ai ) cap ⁢ ⁢ self + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ not ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Aj ) cap ⁢ ⁢ self · A · ⅇ - B ⁢ ⁢ Δ ⁢ ⁢ x ⁡ ( i , j ) - ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Aj ) gap ⁢ ⁢ out · X 4 · ⅇ - Y 4 · Δ ⁢ ⁢ x ⁡ ( i , j ) + C · { ( Q Bi ) cap ⁢ ⁢ self + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ not ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Bj ) cap ⁢ ⁢ self · A · ⅇ - B ⁢ ⁢ Δ ⁢ ⁢ x ⁡ ( i , j ) - ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Bj ) gap ⁢ ⁢ out · X 4 · ⅇ - Y 4 · Δ ⁢ ⁢ x ⁡ ( i , j ) } Equation ⁢ ⁢ ( 6 ) where, (Q Ai ) cap net is the net maximum airflow that can be captured at location A i including contributions from all coolers in the cluster (Q Aj ) cap self is the airflow captured by the cooler at location A j (Q Bj ) cap self is the airflow captured by the cooler at location B j (Q Aj ) gap out is the airflow rate that leaves through the gap at location A j (Q Bj ) gap out is the airflow rate that leaves through the gap at location B j Δx(i,j) is the horizontal distance between locations (slots) i and j A, B, X 4 , and Y 4 are empirical constants C is an empirical “coupling” constant accounting for effects from the opposite row Similarly, the airflow which enters the hot aisle through gaps can also be accounted for by adding two extra terms, Q gap in one for row A and one for row B, when calculating the (Q Aj ) sup net as shown by Equation (7) below: ( Q Ai ) sup ⁢ ⁢ net = ( Q Ai ) sup ⁢ ⁢ self + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ not ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Aj ) sup ⁢ ⁢ self · E · ⅇ - F ⁢ ⁢ Δ ⁢ ⁢ x ⁡ ( i , j ) + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Aj ) gap ⁢ ⁢ in · X 5 · ⅇ - Y 5 · Δ ⁢ ⁢ x ⁡ ( i , j ) + D · { ( Q Bi ) sup ⁢ ⁢ self + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ not ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Bj ) sup ⁢ ⁢ self · E · ⅇ - F ⁢ ⁢ Δ ⁢ ⁢ x ⁡ ( i , j ) + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Bj ) gap ⁢ ⁢ in · X 5 · ⅇ - Y 5 · Δ ⁢ ⁢ x ⁡ ( i , j ) } Equation ⁢ ⁢ ( 7 ) where, (Q Ai ) sup net is the net maximum airflow that can be supplied to location A i including contributions from all racks in the cluster (Q Aj ) sup self is the airflow supplied by the rack at location A j (Q Bj ) sup self is the airflow supplied by the rack at location B j (Q Aj ) gap in is the airflow rate that comes in through the gap at location A j (Q Bj ) gap in is the airflow rate that comes in through the gap at location B j Δx(i,j) is the horizontal distance between locations (slots) i and j E, F, X 5 , and Y 5 are empirical constants D is an empirical “coupling” constant accounting for effects from the opposite row All the empirical constants can be determined by comparing the calculations for a large number of layouts to corresponding “benchmark” cases typically created by CFD simulation. The constants in the model are then adjusted to give the best overall agreement with the benchmark cases based on various metrics including CI. In one example, empirical constants are determined as shown in the following table: TABLE 4 Constants of Imbedded Model for Hot Aisle Clusters X1 1.000 Y1 12.736 X2 1.000 Y2 2.486 X3 10.517 Y3 0.018 X4 1.000 Y4 0.019 X5 1.000 Y5 8.548 The CI is then equal to the ratio of net airflow captured and net airflow supplied at any location expressed as a percentage with values capped at 100%. In the embodiments above, an embedded algebraic model is provided for determining capture index for equipment racks in the hot aisle of an improper cluster of racks. As readily understood by one of ordinary skill in the art, analogous models may be created for determining the capture index for equipment racks in other layouts including cold aisles with row-based coolers, cold aisles with perforated tiles, and cold aisles with both row-based coolers and perforated tiles. Using the algebraic method described above, the CI for racks in an improper cluster may be determined. The results of the analysis can then be used to layout equipment in a data center as described above or to rearrange the layout to ensure that specified cooling requirements are met. In one embodiment, calculations are typically performed for every 6-inch slot along both rows of a cluster so that the tool may be used with standard-width equipment racks; results are averaged over the actual entire rack width before being presented. In methods of at least one embodiment of the invention, after successful modeling of an improper cluster, the results of the model may be used as part of a system to order equipment, ship equipment and install equipment in a data center. In at least some embodiments of the invention discussed herein, the performance of assessments and calculations in real-time refers to processes that are completed in a matter of a few seconds or less rather than several minutes or longer as can happen with complex calculations, such as those involving typical CFD calculations. Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.
A system and method for evaluating equipment in an improper cluster in a data center, the equipment including a plurality of equipment racks, and at least one cooling provider. In one aspect, the method includes receiving data regarding each of the plurality of equipment racks and the at least one cooling provider, the data including a layout of the improper cluster of equipment racks and the at least one cooling provider, storing the received data, identifying at least one gap in the layout, determining cooling performance of at least one of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap, and displaying the layout of the data center, wherein the layout includes an indication of the cooling performance of the at least one of the plurality of equipment racks.
Briefly summarize the main idea's components and working principles as described in the context.
[ "RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §120 of U.S. application Ser.", "No. 12/437,746, entitled “SYSTEM AND METHOD FOR PREDICTING COOLING PERFORMANCE OF ARRANGEMENTS OF EQUIPMENT IN A DATA CENTER,” filed on May 8, 2009, and issued on Aug. 21, 2012, as U.S. Pat. No. 8,249,825, which is herein incorporated by reference in its entirety.", "BACKGROUND 1.", "Field of the Invention At least one embodiment in accordance with the present invention relates generally to systems and methods for data center management and design, and more specifically, to systems and methods for predicting cooling performance of arrangements of equipment in a data center, including improper clusters of equipment in a data center.", "Discussion of Related Art In response to the increasing demands of information-based economies, information technology networks continue to proliferate across the globe.", "One manifestation of this growth is the centralized network data center.", "A centralized network data center typically consists of various information technology equipment, collocated in a structure that provides network connectivity, electrical power and cooling capacity.", "Often the equipment is housed of specialized enclosures termed “racks”", "which integrate these connectivity, power and cooling elements.", "In some data center configurations, these rows are organized into hot and cold aisles to decrease the cost associated with cooling the information technology equipment.", "These characteristics make data centers a cost effective way to deliver the computing power required by many software applications.", "Various processes and software applications, such as the InfrastruXure® Central product available from American Power Conversion Corporation of West Kingston, R.I., have been developed to aid data center personnel in designing and maintaining efficient and effective data centers configurations.", "These tools often guide data center personnel through activities such as designing the data center structure, positioning equipment within the data center prior to installation and repositioning equipment after construction and installation are complete.", "Thus, conventional tool sets provide data center personnel with a standardized and predictable design methodology.", "SUMMARY OF THE INVENTION A first aspect of the invention is directed to a computer-implemented method for evaluating equipment in an improper cluster in a data center, the equipment including a plurality of equipment racks, and at least one rack-based cooling provider.", "The method includes receiving data regarding each of the plurality of equipment racks and the at least one cooling provider, the data including a layout of the improper cluster of equipment racks and the at least one cooling provider, storing the received data, identifying at least one gap in the layout, determining cooling performance of at least one of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap, and displaying the layout of the data center, wherein the layout includes an indication of the cooling performance of the at least one of the plurality of equipment racks.", "In the method, determining cooling performance of the at least one of the plurality of equipment racks may include determining capture index for the at least one of the plurality of equipment racks, and the method may further include determining capture index for each of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap.", "In the method, determining capture index may include determining airflow through the at least one gap, and determining airflow may include determining airflow out of an aisle of the improper cluster through the at least one gap, and determining airflow into the aisle through the at least one gap.", "Further, determining cooling performance of the at least one of the plurality of equipment racks may include determining a value for capture index for the at least one of the plurality of equipment racks with each gap in the layout modeled as a blank panel.", "The method may further include determining a corrector value based on characteristics of the at least one gap, and applying the corrector value to the value for capture index for the at least one of the plurality of equipment racks.", "The method may also include positioning the equipment in the data center in accordance with the layout.", "Another aspect of the invention is directed to a system for evaluating equipment in an improper cluster in a data center, the equipment including a plurality of equipment racks, and at least one rack-based cooling provider.", "The system includes an interface, and a controller configured to receive data regarding each of the plurality of equipment racks and the at least one cooling provider, the data including a layout of the improper cluster of equipment racks and the at least one cooling provider, store the received data in the system, identify at least one gap in the layout, and determine cooling performance of at least one of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap.", "The system may further include a display coupled to the controller, and the controller may be further configured to display the layout of the data center, wherein the layout includes an indication of the cooling performance of the at least one of the plurality of equipment racks.", "The controller may be further configured to determine capture index for the at least one of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap.", "In the system, the controller may be configured to determine airflow out of an aisle of the improper cluster through the at least one gap, and determine airflow into the aisle through the at least one gap.", "The controller may be further configured to determine a value for capture index for the at least one of the plurality of equipment racks with each gap in the layout modeled as a blank panel.", "Further, the controller may be configured to determine a corrector value based on characteristics of the at least one gap, and apply the corrector value to the value for capture index for the at least one of the plurality of equipment racks.", "Another aspect of the invention is directed to a computer readable medium having stored thereon sequences of instruction including instructions that will cause a processor to receive data regarding a layout of an improper cluster of equipment racks and at least one cooling provider, store the received data, identify at least one gap in the layout, and determine cooling performance of at least one of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap.", "The sequences of instruction may further include instructions that will cause the processor to display the layout of the data center on a display associated with the processor, wherein the layout includes an indication of the cooling performance of the at least one of the plurality of equipment racks.", "The medium may also include instructions that will cause the processor to determine capture index for the at least one of the plurality of equipment racks based, at least in part, on characteristics of the at least one gap.", "The sequences of instruction may further include instructions that will cause the processor to determine airflow through the at least one gap, including airflow out of an aisle of the improper cluster through the at least one gap, and determine airflow into the aisle through the at least one gap.", "The sequences of instruction may also include instructions that will cause the processor to determine a value for capture index for the at least one of the plurality of equipment racks with each gap in the layout modeled as a blank panel, and the sequences of instruction may further include instructions that will cause the processor to determine a corrector value based on characteristics of the at least one gap, and apply the corrector value to the value for capture index for the at least one of the plurality of equipment racks.", "BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings are not intended to be drawn to scale.", "In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral.", "For purposes of clarity, not every component may be labeled in every drawing.", "In the drawings: FIG. 1 shows an example computer system with which various aspects in accord with the present invention may be implemented;", "FIG. 2 illustrates an example distributed system including an embodiment;", "FIG. 3 shows a layout of an improper cluster of data equipment racks and coolers;", "and FIG. 4 shows a flowchart of a process for determining cooling characteristics in accordance with one embodiment.", "DETAILED DESCRIPTION At least some embodiments in accordance with the present invention relate to systems and processes through which a user may design data center configurations.", "These systems may facilitate this design activity by allowing the user to create models of data center configurations from which performance metrics may be determined.", "Both the systems and the user may employ these performance metrics to determine alternative data center configurations that meet various design objectives.", "Further, in at least one embodiment, a system will provide an initial layout of data center equipment and conduct a cooling analysis on the layout in real time.", "As described in U.S. patent application Ser.", "No. 12/019,109, titled “System and Method for Evaluating Equipment Rack Cooling”, filed Jan. 24, 2008 (referred to herein as “the '109 Application”), and in U.S. patent application Ser.", "No. 11/342,300, titled “Methods and Systems for Managing Facility Power and Cooling”", "filed Jan. 27, 2006 (referred to herein as “the '300 application”), both of which are assigned to the assignee of the present application, and both of which are hereby incorporated herein by reference in their entirety, typical equipment racks in modern data centers draw cooling air in the front of the rack and exhaust air out the rear of the rack.", "The equipment racks, and in-row coolers are typically arranged in rows in an alternating front/back arrangement creating alternating hot and cool aisles in a data center with the front of each row of racks facing the cool aisle and the rear of each row of racks facing the hot aisle.", "Adjacent rows of equipment racks separated by a cool aisle may be referred to as a cool aisle cluster, and adjacent rows of equipment racks separated by a hot aisle may be referred to as a hot aisle cluster.", "As readily apparent to one of ordinary skill in the art, a row of equipment racks may be part of one hot aisle cluster and one cool aisle cluster.", "In descriptions and claims herein, equipment in racks, or the racks themselves, may be referred to as cooling consumers, and in-row cooling units and/or computer room air conditioners (CRACs) may be referred to as cooling providers.", "In the referenced applications, tools are provided for analyzing the cooling performance of a cluster of racks in a data center.", "In these tools, multiple analyses may be performed on different layouts to attempt to optimize the cooling performance of the data center.", "In typical prior methods and systems for designing and analyzing the layout of clusters in a data center, the methods and systems are either limited for use with simple clusters having two equal-length rows and no gaps or openings in the rows, or if not limited to simple clusters, involve the use of complex algorithms that typically cannot be performed in real-time.", "In data centers, there are many equipment groupings that have unequal row length or contain gaps and are not proper clusters easily analyzed by prior techniques.", "For at least one embodiment, an improper cluster is defined herein as including a two-row grouping of racks, and potentially coolers, around a common cool or hot aisle in which there are gaps in the rows or unequal-length rows.", "A single row may constitute an improper cluster.", "A continuous break between equipment in a row greater than three feet may constitute a break in the row and the row may be divided into multiple proper and improper clusters, or considered to be one improper cluster.", "In at least one embodiment, a method is provided for predicting the cooling performance of an improper cluster in a data center in real-time.", "The method may be incorporated in a system having capabilities for predicting the cooling performance of proper clusters and for performing other design and analysis functions of equipment in a data center.", "The aspects disclosed herein in accordance with the present invention, are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings.", "These aspects are capable of assuming other embodiments and of being practiced or of being carried out in various ways.", "Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting.", "In particular, acts, elements and features discussed in connection with any one or more embodiments are not intended to be excluded from a similar role in any other embodiments.", "For example, according to one embodiment of the present invention, a computer system is configured to perform any of the functions described herein, including but not limited to, configuring, modeling and presenting information regarding specific data center configurations.", "Further, computer systems in embodiments of the data center may be used to automatically measure environmental parameters in a data center, and control equipment, such as chillers or coolers to optimize performance.", "Moreover, the systems described herein may be configured to include or exclude any of the functions discussed herein.", "Thus the invention is not limited to a specific function or set of functions.", "Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.", "The use herein of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.", "Computer System Various aspects and functions described herein in accordance with the present invention may be implemented as hardware or software on one or more computer systems.", "There are many examples of computer systems currently in use.", "These examples include, among others, network appliances, personal computers, workstations, mainframes, networked clients, servers, media servers, application servers, database servers and web servers.", "Other examples of computer systems may include mobile computing devices, such as cellular phones and personal digital assistants, and network equipment, such as load balancers, routers and switches.", "Further, aspects in accordance with the present invention may be located on a single computer system or may be distributed among a plurality of computer systems connected to one or more communications networks.", "For example, various aspects and functions may be distributed among one or more computer systems configured to provide a service to one or more client computers, or to perform an overall task as part of a distributed system.", "Additionally, aspects may be performed on a client-server or multi-tier system that includes components distributed among one or more server systems that perform various functions.", "Thus, the invention is not limited to executing on any particular system or group of systems.", "Further, aspects may be implemented in software, hardware or firmware, or any combination thereof.", "Thus, aspects in accordance with the present invention may be implemented within methods, acts, systems, system elements and components using a variety of hardware and software configurations, and the invention is not limited to any particular distributed architecture, network, or communication protocol.", "FIG. 1 shows a block diagram of a distributed computer system 100 , in which various aspects and functions in accord with the present invention may be practiced.", "Distributed computer system 100 may include one more computer systems.", "For example, as illustrated, distributed computer system 100 includes computer systems 102 , 104 and 106 .", "As shown, computer systems 102 , 104 and 106 are interconnected by, and may exchange data through, communication network 108 .", "Network 108 may include any communication network through which computer systems may exchange data.", "To exchange data using network 108 , computer systems 102 , 104 and 106 and network 108 may use various methods, protocols and standards, including, among others, token ring, ethernet, wireless ethernet, Bluetooth, TCP/IP, UDP, Http, FTP, SNMP, SMS, MMS, SS7, Json, Soap, and Corba.", "To ensure data transfer is secure, computer systems 102 , 104 and 106 may transmit data via network 108 using a variety of security measures including TSL, SSL or VPN among other security techniques.", "While distributed computer system 100 illustrates three networked computer systems, distributed computer system 100 may include any number of computer systems and computing devices, networked using any medium and communication protocol.", "Various aspects and functions in accordance with the present invention may be implemented as specialized hardware or software executing in one or more computer systems including computer system 102 shown in FIG. 1 .", "As depicted, computer system 102 includes processor 110 , memory 112 , bus 114 , interface 116 and storage 118 .", "Processor 110 may perform a series of instructions that result in manipulated data.", "Processor 110 may be a commercially available processor such as an Intel Pentium, Motorola PowerPC, SGI MIPS, Sun UltraSPARC, or Hewlett-Packard PA-RISC processor, but may be any type of processor or controller as many other processors and controllers are available.", "Processor 110 is connected to other system elements, including one or more memory devices 112 , by bus 114 .", "Memory 112 may be used for storing programs and data during operation of computer system 102 .", "Thus, memory 112 may be a relatively high performance, volatile, random access memory such as a dynamic random access memory (DRAM) or static memory (SRAM).", "However, memory 112 may include any device for storing data, such as a disk drive or other non-volatile storage device.", "Various embodiments in accordance with the present invention may organize memory 112 into particularized and, in some cases, unique structures to perform the aspects and functions disclosed herein.", "Components of computer system 102 may be coupled by an interconnection element such as bus 114 .", "Bus 114 may include one or more physical busses, for example, busses between components that are integrated within a same machine, but may include any communication coupling between system elements including specialized or standard computing bus technologies such as IDE, SCSI, PCI and InfiniBand.", "Thus, bus 114 enables communications, for example, data and instructions, to be exchanged between system components of computer system 102 .", "Computer system 102 also includes one or more interface devices 116 such as input devices, output devices and combination input/output devices.", "Interface devices may receive input or provide output.", "More particularly, output devices may render information for external presentation.", "Input devices may accept information from external sources.", "Examples of interface devices include keyboards, mouse devices, trackballs, microphones, touch screens, printing devices, display screens, speakers, network interface cards, etc.", "Interface devices allow computer system 102 to exchange information and communicate with external entities, such as users and other systems.", "Storage system 118 may include a computer readable and writeable nonvolatile storage medium in which instructions are stored that define a program to be executed by the processor.", "Storage system 118 also may include information that is recorded, on or in, the medium, and this information may be processed by the program.", "More specifically, the information may be stored in one or more data structures specifically configured to conserve storage space or increase data exchange performance.", "The instructions may be persistently stored as encoded signals, and the instructions may cause a processor to perform any of the functions described herein.", "The medium may, for example, be optical disk, magnetic disk or flash memory, among others.", "In operation, the processor or some other controller may cause data to be read from the nonvolatile recording medium into another memory, such as memory 112 , that allows for faster access to the information by the processor than does the storage medium included in storage system 118 .", "The memory may be located in storage system 118 or in memory 112 , however, processor 110 may manipulate the data within the memory 112 , and then copies the data to the medium associated with storage system 118 after processing is completed.", "A variety of components may manage data movement between the medium and integrated circuit memory element and the invention is not limited thereto.", "Further, the invention is not limited to a particular memory system or storage system.", "Although computer system 102 is shown by way of example as one type of computer system upon which various aspects and functions in accordance with the present invention may be practiced, aspects of the invention are not limited to being implemented on the computer system as shown in FIG. 1 .", "Various aspects and functions in accord with the present invention may be practiced on one or more computers having a different architectures or components than that shown in FIG. 1 .", "For instance, computer system 102 may include specially-programmed, special-purpose hardware, such as for example, an application-specific integrated circuit (ASIC) tailored to perform a particular operation disclosed herein.", "While another embodiment may perform the same function using several general-purpose computing devices running MAC OS System X with Motorola PowerPC processors and several specialized computing devices running proprietary hardware and operating systems.", "Computer system 102 may be a computer system including an operating system that manages at least a portion of the hardware elements included in computer system 102 .", "Usually, a processor or controller, such as processor 110 , executes an operating system which may be, for example, a Windows-based operating system, such as, Windows NT, Windows 2000 (Windows ME), Windows XP or Windows Vista operating systems, available from the Microsoft Corporation, a MAC OS System X operating system available from Apple Computer, one of many Linux-based operating system distributions, for example, the Enterprise Linux operating system available from Red Hat Inc., a Solaris operating system available from Sun Microsystems, or a UNIX operating system available from various sources.", "Many other operating systems may be used, and embodiments are not limited to any particular implementation.", "The processor and operating system together define a computer platform for which application programs in high-level programming languages may be written.", "These component applications may be executable, intermediate, for example, C−, bytecode or interpreted code which communicates over a communication network, for example, the Internet, using a communication protocol, for example, TCP/IP.", "Similarly, aspects in accord with the present invention may be implemented using an object-oriented programming language, such as .", "Net, SmallTalk, Java, C++, Ada, or C# (C-Sharp).", "Other object-oriented programming languages may also be used.", "Alternatively, functional, scripting, or logical programming languages may be used.", "Additionally, various aspects and functions in accordance with the present invention may be implemented in a non-programmed environment, for example, documents created in HTML, XML or other format that, when viewed in a window of a browser program, render aspects of a graphical-user interface or perform other functions.", "Further, various embodiments in accord with the present invention may be implemented as programmed or non-programmed elements, or any combination thereof.", "For example, a web page may be implemented using HTML while a data object called from within the web page may be written in C++.", "Thus, the invention is not limited to a specific programming language and any suitable programming language could also be used.", "Further, in at least one embodiment, the tool may be implemented using VBA Excel.", "A computer system included within an embodiment may perform additional functions outside the scope of the invention.", "For instance, aspects of the system may be implemented using an existing commercial product, such as, for example, Database Management Systems such as SQL Server available from Microsoft of Seattle Wash.", ", Oracle Database from Oracle of Redwood Shores, Calif.", ", and MySQL from MySQL AB of Uppsala, Sweden or integration software such as Web Sphere middleware from IBM of Armonk, N.Y. However, a computer system running, for example, SQL Server may be able to support both aspects in accord with the present invention and databases for sundry applications not within the scope of the invention.", "Example System Architecture FIG. 2 presents a context diagram including physical and logical elements of distributed system 200 .", "As shown, distributed system 200 is specially configured in accordance with the present invention.", "The system structure and content recited with regard to FIG. 2 is for exemplary purposes only and is not intended to limit the invention to the specific structure shown in FIG. 2 .", "As will be apparent to one of ordinary skill in the art, many variant system structures can be architected without deviating from the scope of the present invention.", "The particular arrangement presented in FIG. 2 was chosen to promote clarity.", "Information may flow between the elements, components and subsystems depicted in FIG. 2 using any technique.", "Such techniques include, for example, passing the information over the network via TCP/IP, passing the information between modules in memory and passing the information by writing to a file, database, or some other non-volatile storage device.", "Other techniques and protocols may be used without departing from the scope of the invention.", "Referring to FIG. 2 , system 200 includes user 202 , interface 204 , data center design and management system 206 , communications network 208 and data center database 210 .", "System 200 may allow user 202 , such as a data center architect or other data center personnel, to interact with interface 204 to create or modify a model of one or more data center configurations.", "According to one embodiment, interface 204 may include aspects of the floor editor and the rack editor as disclosed in Patent Cooperation Treaty Application No. PCT/US08/63675, entitled METHODS AND SYSTEMS FOR MANAGING FACILITY POWER AND COOLING, filed on May 15, 2008, which is incorporated herein by reference in its entirety and is hereinafter referred to as PCT/US08/63675.", "In other embodiments, interface 204 may be implemented with specialized facilities that enable user 202 to design, in a drag and drop fashion, a model that includes a representation of the physical layout of a data center or any subset thereof.", "This layout may include representations of data center structural components as well as data center equipment.", "The features of interface 204 , as may be found in various embodiments in accordance with the present invention, are discussed further below.", "In at least one embodiment, information regarding a data center is entered into system 200 through the interface, and assessments and recommendations for the data center are provided to the user.", "Further, in at least one embodiment, optimization processes may be performed to optimize cooling performance and energy usage of the data center.", "As shown in FIG. 2 , data center design and management system 206 presents data design interface 204 to user 202 .", "According to one embodiment, data center design and management system 206 may include the data center design and management system as disclosed in PCT/US08/63675.", "In this embodiment, design interface 204 may incorporate functionality of the input module, the display module and the builder module included in PCT/US08/63675 and may use the database module to store and retrieve data.", "As illustrated, data center design and management system 206 may exchange information with data center database 210 via network 208 .", "This information may include any information required to support the features and functions of data center design and management system 206 .", "For example, in one embodiment, data center database 210 may include at least some portion of the data stored in the data center equipment database described in PCT/US08/63675.", "In another embodiment, this information may include any information required to support interface 204 , such as, among other data, the physical layout of one or more data center model configurations, the production and distribution characteristics of the cooling providers included in the model configurations, the consumption characteristics of the cooling consumers in the model configurations, and a listing of equipment racks and cooling providers to be included in a cluster.", "In one embodiment, data center database 210 may store types of cooling providers, the amount of cool air provided by each type of cooling provider, and a temperature of cool air provided by the cooling provider.", "Thus, for example, data center database 210 includes records of a particular type of CRAC unit that is rated to deliver airflow at the rate of 5,600 cfm at a temperature of 68 degrees Fahrenheit.", "In addition, the data center database 210 may store one or more cooling metrics, such as inlet and outlet temperatures of the CRACs and inlet and outlet temperatures of one or more equipment racks.", "The temperatures may be periodically measured and input into the system, or in other embodiments, the temperatures may be continuously monitored using devices coupled to the system 200 .", "Data center database 210 may take the form of any logical construction capable of storing information on a computer readable medium including, among other structures, flat files, indexed files, hierarchical databases, relational databases or object oriented databases.", "The data may be modeled using unique and foreign key relationships and indexes.", "The unique and foreign key relationships and indexes may be established between the various fields and tables to ensure both data integrity and data interchange performance.", "The computer systems shown in FIG. 2 , which include data center design and management system 206 , network 208 and data center equipment database 210 , each may include one or more computer systems.", "As discussed above with regard to FIG. 1 , computer systems may have one or more processors or controllers, memory and interface devices.", "The particular configuration of system 200 depicted in FIG. 2 is used for illustration purposes only and embodiments of the invention may be practiced in other contexts.", "Thus, embodiments of the invention are not limited to a specific number of users or systems.", "In at least one embodiment, which will now be described, a tool is provided that predicts cooling performance for an improper hot aisle cluster in real time and displays results of the prediction along with a model of the improper cluster.", "FIG. 3 shows a model of an improper cluster of racks 300 .", "The improper cluster includes two rows of racks A and B separated by a hot aisle 302 .", "Each row includes racks R and coolers C. Row A includes 6 racks and 3 coolers and Row B includes 4 racks and 1 cooler.", "Row B also includes two gaps 304 and 306 .", "In one embodiment, the racks are standard nineteen inch equipment racks having an overall width of 24 inches and the coolers have a width of 12 inches.", "However, embodiments of the invention may be used with racks and coolers of other sizes.", "Gap 304 is approximately two feet wide and gap 306 , representing a difference in lengths of the Rows A and B, is approximately 4 feet wide.", "As shown in FIG. 3 , in accordance with some embodiments, the results of the prediction of cooling performance may be displayed directly on the racks in the model.", "In FIG. 3 , the results are shown as capture index (in percentage) on each of the racks in the model.", "In embodiments of the invention, different performance metrics can be used to evaluate the cooling performance of an improper cluster.", "In one embodiment, the performance metric is capture index.", "Capture index, and methods of determining capture index are described in greater detail in the '109 and '300 applications referenced above.", "The cold-aisle capture index for a rack is defined in at least some embodiments as the fraction of air ingested by the rack which originates from local cooling resources (e.g., perforated floor tiles or local coolers).", "The hot-aisle capture index is defined as the fraction of air exhausted by a rack which is captured by local extracts (e.g., local coolers or return vents).", "CI therefore varies between 0 and 100% with better cooling performance generally indicated by greater CI values.", "In a cold-aisle analysis, high CI's ensure that the bulk of the air ingested by a rack comes from local cooling resources rather than being drawn from the room environment or from air which may have already been heated by electronics equipment.", "In this case, rack inlet temperatures will closely track the perforated-tile airflow temperatures and, assuming these temperatures are within the desired range, acceptable cooling will be achieved.", "In a hot-aisle analysis, high CI's ensure that rack exhaust is captured locally and there is little heating of the surrounding room environment.", "While good (high) CI values typically imply good cooling performance;", "low CI values do not necessarily imply unacceptable cooling performance.", "For example, in a rack in a raised-floor environment which draws most of its airflow from the surrounding room environment rather than from the perforated tiles, the rack's cold-aisle CI will be low;", "however, if the surrounding room environment is sufficiently cool, the rack's inlet temperature may still be acceptable.", "In this case, the rack's cooling needs are met by the external room environment rather than perforated tiles within the rack's cluster.", "If this process is repeated many times across the data center, facility cooling will be complex and may be unpredictable.", "High CI values lead to inherently scalable cluster layouts and more predictable room environments.", "In one embodiment, a tool operable on one or more computer systems described above determines capture index for racks of an improper cluster.", "In doing so, the improper cluster is first analyzed as a proper cluster, with all gaps and any row-length mismatches filled with blanking panels (or “dummy”", "racks with zero airflow).", "The capture index is determined for each of the racks in the proper cluster using any of a number of techniques for determining the CI, including the algebraic, neural network and PDA-CFD techniques described in the '109 and '300 applications referenced above.", "Once the CI is determined for the proper cluster, a corrector model is applied to the results to correct for the negative effects created by gaps in the improper cluster.", "Gaps in the rows of an improper cluster provide an opening to allow air to escape from the aisle between the two rows in a cluster having a negative effect on the capture index.", "The corrector model determines the percentage of reduction of the CI for each rack in the improper cluster.", "The final CI for a rack i in an improper cluster can be expressed as follows using equation (1): CI i gap =CI i blank ·(1−Corrector i ) Equation (1) where, CI i blank is the “benchmark”", "CI value for rack i when all the gaps and row length mismatches in the cluster are replaced by blanking panels.", "Corrector i is the percentage reduction (expressed as a decimal value) of the CI of rack i. In equations discussed herein, rack locations are designated as A i and B j .", "The designation A or B indicates which row the rack is contained in and the subscript i or j indicates the slot in the row containing the rack, which may be counted from left or right.", "For example, in the cluster of FIG. 3 , Row A includes 6 racks and 3 coolers for a total of 9 objects or 30 6-inch slots and Row B includes 4 racks, one cooler and two gaps for a totally of 7 objects or 30 6-inch slots.", "The CI corrector is related to the distance between the rack of interest and all the gaps in the improper cluster where each 6-inch “slot”", "(in an open “gap section”", "like 304 or 306 of FIG. 3 ) is typically considered one gap.", "In one embodiment, the percentage reduction of the CI value of a certain rack at location A i can be adequately represented as follows: ⁢ Equation ⁢ ⁢ ( 2 ) Corrector Ai = X · ∑ j all ⁢ ⁢ gaps ⁢ ⁢ in ⁢ ⁢ row ⁢ ⁢ A ⁢ ⁢ ⅇ - Y · Δ ⁢ ⁢ x ⁡ ( i , j ) + Z · ∑ j all ⁢ ⁢ gaps ⁢ ⁢ in ⁢ ⁢ row ⁢ ⁢ B ⁢ ⁢ ⅇ - Y · Δ ⁢ ⁢ x ⁡ ( i , j ) ∑ j all ⁢ ⁢ objects ⁢ ⁢ in ⁢ ⁢ row ⁢ ⁢ A ⁢ ⁢ ⅇ - Y · Δ ⁢ ⁢ x ⁡ ( i , j ) + Z · ∑ j all ⁢ ⁢ objects ⁢ ⁢ in ⁢ ⁢ row ⁢ ⁢ B ⁢ ⁢ ⅇ - Y · Δ ⁢ ⁢ x ⁡ ( i , j ) where, Corrector Ai is the percentage reduction (expressed as a decimal value) of the CI of rack i in Row A X, Y, and Z are empirical constants Δx(i,j) is the horizontal distance between locations (slots) i and j. In equation (2), the numerator is equal to zero when there are no gaps and hence the Corrector Ai becomes zero.", "In this case, the cluster is a proper cluster and no correction is needed.", "The closer a gap is to a rack, the larger the Corrector for that rack and hence the lower the CI of the rack.", "The empirical constants X, Y and Z can be determined by comparing the calculations for a large number of layouts to corresponding “benchmark”", "cases typically created by CFD simulation.", "The constants in the model are then adjusted to give the best overall agreement with the benchmark cases based on various metrics including CI.", "The Corrector described herein can be applied to any type of improper cluster, which might include hot aisle improper clusters with row-based coolers and cold aisle improper clusters with row-based coolers and/or perforated tiles.", "In one example, for hot aisle improper clusters with row-based coolers, constants X and Y are fixed for all cluster configurations, but constant Z varies with aisle width as shown in the table below.", "For a single-row improper cluster, Z is 2.", "TABLE 1 Constants vs.", "Aisle Width for Hot Aisle Clusters with Row-Based Coolers Hot Aisle Width (ft) Constant 3 4 5 6 X 1 1 1 1 Y 0.073 0.073 0.073 0.073 Z 3 2.33 1.67 1 In one example, for cold aisle improper clusters with row-based coolers, constants X and Y are fixed for all cluster configurations, but the constant Z varies with aisle width as shown in the table below.", "For a single row improper cluster, Z is 2.", "TABLE 2 Constants vs.", "Aisle Width for Cold Aisle Clusters with Row-Based Coolers Cold Aisle Width (ft) Constant 4 6 X 1 1 Y 0.123 0.123 Z 3 1 In one example, for cold aisle improper clusters with perforated tiles, constants X and Y are fixed for all cluster configurations, but constant Z varies with aisle width as shown in the table below.", "For a single row improper cluster, Z is 0.18.", "TABLE 3 Constants vs.", "Aisle Width for Cold Aisle Clusters with Perforated Tiles Cold Aisle Width (ft) Constant 4 6 X 1 1 Y 2.8 2.8 Z 0.1 0.05 In one example, for cold aisle improper clusters with both row-based coolers and perforated tiles, the calculation of constant X can be expressed as follows using equation (3): X=α·X PT +(1−α)· X IR Equation (3) where, X PT is the constant X used in the cold-aisle-cluster-with-perforated-tiles applications for the same cold aisle width;", "X IR is the constant X used in the cold aisle cluster-with-row-based-coolers applications for the same cold aisle width;", "and α is the fraction of supply airflow delivered by the perforated tiles.", "Constants Y and Z are be determined in a similar manner.", "It is noted that the effect of the presence of gaps on cooling performance is greater for layouts with row-based coolers than for raised floor applications due to the strong horizontal airflow patterns associated with row-based coolers.", "FIG. 4 provides a flow chart of a process 400 for determining the CI for equipment racks of an improper cluster using the corrector model described above in accordance with one embodiment.", "First at stage 402 of the process 400 , information regarding the layout for the improper cluster is loaded into the tool.", "The information may include power consumption values for each of the racks, cooling capacities of each of the coolers and location of the racks and coolers in the layout.", "At least some of the information may have previously been stored in a database contained in a computer system implementing the tool transmitted to the computer system via a network or loaded into the system by a user.", "At stage 404 , gaps are identified in the improper cluster, and the gaps (including mismatches at the end of a row) are covered in the layout with blanking panels or replaced with racks having no airflow.", "The CI for each rack in the improper cluster is then determined (stage 406 ) using one of a number of techniques as discussed above.", "As part of stage 406 , the Corrector for each rack is determined and applied to the CI.", "At stage 408 , the model is then displayed (and may be printed) with the corrected CI for each of the racks.", "At stage 410 , the process ends.", "In some embodiments, the displayed model may provide additional indications for out of tolerance CI values, such as warning labels or through the use of color codes.", "Further, in some embodiments, when an out of tolerance condition is indicated, a user may be prompted to rearrange the racks to find a more satisfactory solution.", "In another embodiment, a tool for determining CI for equipment racks in improper hot aisle clusters utilizes an embedded algebraic model.", "This embedded algebraic model may be included within existing algebraic models (or similar models) for proper clusters or may be implemented as a stand alone tool.", "One example of an algebraic model with which the embedded algebraic model may be used is described in the '109 and '300 applications referenced above.", "In the embedded algebraic model of one embodiment, airflow which passes through gaps is explicitly estimated in order to account for the unfavorable effects of gaps on the CI of each rack.", "In general, there are two types of airflows through any given gap: an inflow, Q gap in , and an outflow, Q gap out .", "Both “in”", "and “out”", "airflows may be simultaneously present in the same gap.", "The model of airflows used in at least one embodiment of the tool need not have a direct, accurate physical interpretation for the tool to be effective.", "In other words, if the “in”", "term computed by the tool is, for example, 375 cfm;", "it does not mean that the actual inflow through the gap must be 375 cfm for the tool to be effective.", "Rather, the use of the “in”", "and “out”", "flow terms allow for more degrees of freedom in the tool with which the tool may be “tuned.”", "The inflow, Q gap in , is determined by the cooler airflow rate as well as the distance between all the coolers and the gap.", "It has been found that the airflow rate which comes in through a gap i in row A into a hot aisle can be adequately represented as shown in Equation (4) below: ( Q Ai ) gap ⁢ ⁢ in = ∑ all ⁢ ⁢ j ≠ i all ⁢ ⁢ coolers ⁢ ⁢ j ⁢ ⁢ in ⁢ ⁢ Row ⁢ ⁢ A ⁢ ⁢ ( Q Aj ) cap ⁢ ⁢ self · X 1 · ⅇ - Y 1 · Δ ⁢ ⁢ x ⁡ ( i , j ) + X 3 · ∑ all ⁢ ⁢ j ≠ i all ⁢ ⁢ coolers ⁢ ⁢ j ⁢ ⁢ in ⁢ ⁢ Row ⁢ ⁢ B ⁢ ⁢ ( Q Bj ) cap ⁢ ⁢ self · X 1 · ⅇ - Y 1 · Δ ⁢ ⁢ x ⁡ ( i , j ) Equation ⁢ ⁢ ( 4 ) where, (Q Ai ) gap in is the airflow rate that comes in through the gap at location A i (Q Aj ) cap self is the airflow rate captured by the cooler at location A j (Q Bj ) cap self is the airflow rate captured by the cooler at location B j Δx(i,j) is the horizontal distance between locations (slots) i and j X 1 and Y 1 are empirical constants and X 3 is the empirical “coupling”", "constant accounting for effects from the opposite row.", "Similarly, the outflow, Q gap out can be determined by the rack airflow rate as well as the distance between all the racks and the gap.", "It has been found that the airflow rate which leaves the hot aisle through a gap i in row A can be adequately represented as: ( Q Ai ) gap ⁢ ⁢ out = ∑ all ⁢ ⁢ j ≠ i all ⁢ ⁢ rock ⁢ ⁢ j ⁢ ⁢ in ⁢ ⁢ Row ⁢ ⁢ A ⁢ ⁢ ( Q Aj ) sup ⁢ ⁢ self · X 2 · ⅇ - Y 2 · Δ ⁢ ⁢ x ⁡ ( i , j ) + Y 3 · ∑ all ⁢ ⁢ j ≠ i all ⁢ ⁢ rock ⁢ ⁢ j ⁢ ⁢ in ⁢ ⁢ Row ⁢ ⁢ B ⁢ ⁢ ( Q Bj ) sup ⁢ ⁢ self · X 2 · ⅇ - Y 2 · Δ ⁢ ⁢ x ⁡ ( i , j ) Equation ⁢ ⁢ ( 5 ) where, (Q Ai ) gap out is the airflow rate that leaves through the gap at location A i (Q Aj ) sup self is the airflow rate supplied by the rack at location A j (Q Bj ) sup self is the airflow rate supplied by the rack at location B j Δx(i,j) is the horizontal distance between locations (slots) i and j X 2 and Y 2 are empirical constants and Y 3 is the empirical “coupling”", "constant accounting for effects from the opposite row.", "The constants are, again, determined by comparing the calculations for a large number of layouts to corresponding “benchmark”", "cases typically created by CFD simulation.", "The constants in the model are then adjusted to give the best overall agreement with the benchmark cases based on various metrics including CI.", "When calculating the net airflow that can be supplied to a particular location A i using the current hot-aisle algebraic calculator, the tool accounts for the airflow which escapes the hot aisle through all the gaps.", "To accomplish this, two extra terms are subtracted from the equation to calculate the (Q Aj ) cap net (from the '109 Application referenced above) one for row A and one for Row B as shown by Equation (6) below: ( Q Ai ) cap ⁢ ⁢ net = ( Q Ai ) cap ⁢ ⁢ self + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ not ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Aj ) cap ⁢ ⁢ self · A · ⅇ - B ⁢ ⁢ Δ ⁢ ⁢ x ⁡ ( i , j ) - ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Aj ) gap ⁢ ⁢ out · X 4 · ⅇ - Y 4 · Δ ⁢ ⁢ x ⁡ ( i , j ) + C · { ( Q Bi ) cap ⁢ ⁢ self + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ not ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Bj ) cap ⁢ ⁢ self · A · ⅇ - B ⁢ ⁢ Δ ⁢ ⁢ x ⁡ ( i , j ) - ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Bj ) gap ⁢ ⁢ out · X 4 · ⅇ - Y 4 · Δ ⁢ ⁢ x ⁡ ( i , j ) } Equation ⁢ ⁢ ( 6 ) where, (Q Ai ) cap net is the net maximum airflow that can be captured at location A i including contributions from all coolers in the cluster (Q Aj ) cap self is the airflow captured by the cooler at location A j (Q Bj ) cap self is the airflow captured by the cooler at location B j (Q Aj ) gap out is the airflow rate that leaves through the gap at location A j (Q Bj ) gap out is the airflow rate that leaves through the gap at location B j Δx(i,j) is the horizontal distance between locations (slots) i and j A, B, X 4 , and Y 4 are empirical constants C is an empirical “coupling”", "constant accounting for effects from the opposite row Similarly, the airflow which enters the hot aisle through gaps can also be accounted for by adding two extra terms, Q gap in one for row A and one for row B, when calculating the (Q Aj ) sup net as shown by Equation (7) below: ( Q Ai ) sup ⁢ ⁢ net = ( Q Ai ) sup ⁢ ⁢ self + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ not ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Aj ) sup ⁢ ⁢ self · E · ⅇ - F ⁢ ⁢ Δ ⁢ ⁢ x ⁡ ( i , j ) + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Aj ) gap ⁢ ⁢ in · X 5 · ⅇ - Y 5 · Δ ⁢ ⁢ x ⁡ ( i , j ) + D · { ( Q Bi ) sup ⁢ ⁢ self + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ not ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Bj ) sup ⁢ ⁢ self · E · ⅇ - F ⁢ ⁢ Δ ⁢ ⁢ x ⁡ ( i , j ) + ∑ all ⁢ ⁢ j ≠ i and ⁢ ⁢ j ⁢ ⁢ is ⁢ ⁢ a ⁢ ⁢ gap ⁢ ⁢ ( Q Bj ) gap ⁢ ⁢ in · X 5 · ⅇ - Y 5 · Δ ⁢ ⁢ x ⁡ ( i , j ) } Equation ⁢ ⁢ ( 7 ) where, (Q Ai ) sup net is the net maximum airflow that can be supplied to location A i including contributions from all racks in the cluster (Q Aj ) sup self is the airflow supplied by the rack at location A j (Q Bj ) sup self is the airflow supplied by the rack at location B j (Q Aj ) gap in is the airflow rate that comes in through the gap at location A j (Q Bj ) gap in is the airflow rate that comes in through the gap at location B j Δx(i,j) is the horizontal distance between locations (slots) i and j E, F, X 5 , and Y 5 are empirical constants D is an empirical “coupling”", "constant accounting for effects from the opposite row All the empirical constants can be determined by comparing the calculations for a large number of layouts to corresponding “benchmark”", "cases typically created by CFD simulation.", "The constants in the model are then adjusted to give the best overall agreement with the benchmark cases based on various metrics including CI.", "In one example, empirical constants are determined as shown in the following table: TABLE 4 Constants of Imbedded Model for Hot Aisle Clusters X1 1.000 Y1 12.736 X2 1.000 Y2 2.486 X3 10.517 Y3 0.018 X4 1.000 Y4 0.019 X5 1.000 Y5 8.548 The CI is then equal to the ratio of net airflow captured and net airflow supplied at any location expressed as a percentage with values capped at 100%.", "In the embodiments above, an embedded algebraic model is provided for determining capture index for equipment racks in the hot aisle of an improper cluster of racks.", "As readily understood by one of ordinary skill in the art, analogous models may be created for determining the capture index for equipment racks in other layouts including cold aisles with row-based coolers, cold aisles with perforated tiles, and cold aisles with both row-based coolers and perforated tiles.", "Using the algebraic method described above, the CI for racks in an improper cluster may be determined.", "The results of the analysis can then be used to layout equipment in a data center as described above or to rearrange the layout to ensure that specified cooling requirements are met.", "In one embodiment, calculations are typically performed for every 6-inch slot along both rows of a cluster so that the tool may be used with standard-width equipment racks;", "results are averaged over the actual entire rack width before being presented.", "In methods of at least one embodiment of the invention, after successful modeling of an improper cluster, the results of the model may be used as part of a system to order equipment, ship equipment and install equipment in a data center.", "In at least some embodiments of the invention discussed herein, the performance of assessments and calculations in real-time refers to processes that are completed in a matter of a few seconds or less rather than several minutes or longer as can happen with complex calculations, such as those involving typical CFD calculations.", "Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art.", "Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention.", "Accordingly, the foregoing description and drawings are by way of example only." ]
FIELD OF THE INVENTION [0001] This invention generally relates to wired and wireless ultra wideband (UWB) data communications apparatus and methods, and in particular to UWB receiver systems and architectures. The benefit of U.S. provisional 60/518,344 filed Nov. 10, 2003 is claimed. BACKGROUND TO THE INVENTION [0002] Techniques for UWB communication developed from radar and other military applications, and pioneering work was carried out by Dr G. F. Ross, as described in U.S. Pat. No. 3,728,632. Ultra-wideband communications systems employ very short pulses of electromagnetic radiation (impulses) with short rise and fall times, resulting in a spectrum with a very wide bandwidth. Some systems employ direct excitation of an antenna with such a pulse which then radiates with its characteristic impulse or step response (depending upon the excitation). Such systems are referred to as carrierless or “carrier free” since the resulting rf emission lacks any well-defined carrier frequency. However other UWB systems radiate one or a few cycles of a high frequency carrier and thus it is possible to define a meaningful centre frequency and/or phase despite the large signal bandwidth. The US Federal Communications Commission (FCC) defines UWB as a −10 dB bandwidth of at least 25% of a centre (or average) frequency or a bandwidth of at least 1.5 GHz; the US DARPA definition is similar but refers to a −20 dB bandwidth. Such formal definitions are useful and clearly differentiates UWB systems from conventional narrow and wideband systems but the techniques described in this specification are not limited to systems falling within this precise definition and may be employed with similar systems employing very short pulses of electromagnetic radiation. [0003] UWB communications systems have a number of advantages over conventional systems. Broadly speaking, the very large bandwidth facilitates very high data rate communications and since pulses of radiation are employed the average transmit power (and also power consumption) may be kept low even though the power in each pulse may be relatively large. Also, since the power in each pulse is spread over a large bandwidth the power per unit frequency may be very low indeed, allowing UWB systems to coexist with other spectrum users and, in military applications, providing a low probability of intercept. The short pulses also make UWB communications systems relatively unsusceptible to multipath effects since multiple reflections can in general be resolved. Finally UWB systems lend themselves to a substantially all digital implementation, with consequent cost savings and other advantages. [0004] FIG. 1 a shows an example of an analogue UWB transceiver 100 . This comprises an transmit/receive antenna 102 with a characteristic impulse response indicated by bandpass filter (BPF) 104 (although in some instances a bandpass filter may be explicitly included), couples to a transmit/receive switch 106 . [0005] The transmit chain comprises an impulse generator 108 modulatable by a baseband transmit data input 110 , and an antenna driver 112 . The driver may be omitted since only a small output voltage swing is generally required. One of a number of modulation techniques may be employed, typically either OOK (on-off keying i.e. transmitting or not transmitting a pulse), M-ary amplitude shift keying (pulse amplitude modulation), or PPM (pulse position modulation i.e. dithering the pulse position). Typically the transmitted pulse has a duration of <Ins and may have a bandwidth of the order of gigahertz. [0006] The receive chain typically comprises a low noise amplifier (LNA) and automatic gain control (AGC) stage 114 followed by a correlator or matched filter (MF) 116 , matched to the received pulse shape so that it outputs an impulse when presented with rf energy having the correct (matching) pulse shape. The output of MF 116 is generally digitised by an analogue-to-digital converter (ADC) 118 and then presented to a (digital or software-based) variable gain threshold circuit 120 , the output of which comprises the received data. The skilled person will understand that forward error correction (FEC) such as block error coding and other baseband processing may also be employed, but such techniques are well-known and conventional and hence these is omitted for clarity. [0007] FIG. 1 b shows one example of a carrier-based UWB transmitter 122 . A similar transmitter is described in more detail in U.S. Pat. No. 6,026,125. This form of transmitter allows the UWB transmission centre frequency and bandwidth to be controlled and, because it is carrier-based, allows the use of frequency and phase as well as amplitude and position modulation. Thus, for example, QAM (quadrature amplitude modulation) or M-ary PSK (phase shift keying) may be employed. [0008] Referring to FIG. 1 b , an oscillator 124 generates a high frequency carrier which is gated by a mixer 126 which, in effect, acts as a high speed switch. A second input to the mixer is provided by an impulse generator 128 , filtered by an (optional) bandpass filter 130 . The amplitude of the filtered impulse determines the time for which the mixer diodes are forward biased and hence the effective pulse width and bandwidth of the UWB signal at the output of the mixer. The bandwidth of the UWB signal is similarly also determined by the bandwidth of filter 130 . The centre frequency and instantaneous phase of the UWB signal is determined by oscillator 124 , and may be modulated by a data input 132 . An example of a transmitter with a centre frequency of 1.5 GHz and a bandwidth of 400 MHz is described in U.S. Pat. No. 6,026,125. Pulse to pulse coherency can be achieved by phase locking the impulse generator to the oscillator. [0009] The output of mixer 126 is processed by a bandpass filter 134 to reject out-of-band frequencies and undesirable mixer products, optionally attenuated by a digitally controlled rf attenuator 136 to allow additional amplitude modulation, and then passed to a wideband power amplifier 138 such as a MMIC (monolithic microwave integrated circuit), and transmit antenna 140 . The power amplifier may be gated on and off in synchrony with the impulses from generator 128 , as described in US'125, to reduce power consumption. [0010] FIG. 1 c shows a similar transmitter to that of FIG. 1 b , in which like elements have like reference numerals. The transmitter of FIG. 1 c is, broadly speaking, a special case of the transmitter of FIG. 1 b in which the oscillator frequency has been set to zero. The output of oscillator 124 of FIG. 1 b is effectively a dc level which serves to keep mixer 126 always on, so these elements are omitted (and the impulse generator or its output is modulated). [0011] FIG. 1 d shows an alternative carrier-based UWB transmitter 142 , also described in U.S. Pat. No. 6,026,125. Again like elements to those of FIG. 1 b are shown by like reference numerals. [0012] In the arrangement of FIG. 1 d a time gating circuit 144 gates the output of oscillator 124 under control of a timing signal 146 . The pulse width of this timing signal determines the instantaneous UWB signal bandwidth. Thus the transmitted signal UWB bandwidth may be adjusted by adjusting the width of this pulse. [0013] Ultra-wideband receivers suitable for use with the UWB transmitters of FIGS. 1 b to 1 d are described in U.S. Pat. No. 5,901,172. These receivers use tunnel diode-based detectors to enable single pulse detection at high speeds (several megabits per second) with reduced vulnerability to in-band interference. Broadly speaking a tunnel diode is switched between active and inactive modes, charge stored in the diode being discharged during its inactive mode. The tunnel diode acts, in effect, as a time-gated matched filter, and the correlation operation is synchronised to the incoming pulses. [0014] FIG. 1 e shows another example of a known UWB transmitter 148 , described in U.S. Pat. No. 6,304,623. In FIG. 1 e a pulser 150 generates an rf pulse for transmission by antenna 152 under control of a timing signal 154 provided by a precision timing generator 156 , itself controlled by a stable timebase 158 . A code generator 160 receives a reference clock from the timing generator and provides pseudo-random time offset commands to the timing generator for dithering the transmitter pulse positions. This has the effect of spreading and flattening the comb-like spectrum which would otherwise be produced by regular, narrow pulses (in some systems amplitude modulation may be employed for a similar effect). [0015] FIG. 1 f shows a corresponding receiver 162 , also described in US'623. This uses a similar timing generator 164 , timebase 166 and code generator 168 (generating the same pseudo-random sequence), but the timebase 166 is locked to the received signal by a tracking loop filter 170 . The timing signal output of timing generator 164 drives a template generator 172 which outputs a template signal and a correlator/sampler 176 and accumulator 178 samples and correlates the received signal with the template, integrating over an aperture time of the correlator to produce an output which is sampled at the end of an integration cycle by a detector 180 to determine whether a one or a zero has been received. [0016] FIG. 1 g shows a UWB transceiver 182 employing spread spectrum-type coding techniques. A transceiver of the general type is described in more detail in U.S. Pat. No. 6,400,754, to which reference may be made. [0017] In FIG. 1 g a receive antenna 184 and low noise amplifier 186 provide one input to a time-integrating correlator 188 . A second input to the correlator is provided by a code sequence generator 190 which generates a spread spectrum-type code such as a Kasami code, that is a code with a high auto-correlation coefficient from a family of codes with low cross-correlation coefficients. Correlator 188 multiplies the analogue input signal by the reference code and integrates over a code sequence period and may comprise a matched filter with a plurality of phases representing different time alignments of the input signal and reference code. The correlator output is digitised by analogue-to-digital converter 192 which provides an output to a bus 194 controlled by a processor 196 with memory 198 the code sequence generator 190 is driven by a crystal oscillator driven clock 200 a transmit antenna driver 202 receives data from bus 194 which is multiplied by a code sequence from generator 190 and transmitted from transmit antenna 204 . In operation coded sequences of impulse doublets are received and transmitted, in one arrangement each bit comprising a 1023-chip sequence of 10 ns chips, thus having a duration of 10 μs and providing 30 dB processing gain. Shorter spreading sequences and/or faster clocks may be employed for higher bit rates. [0018] The transceiver described in U.S. Pat. No. 6,400,754 uses a modification of a frequency-independent current-mode shielded loop antenna (described in U.S. Pat. No. 4,506,267) comprising a flat rectangular conducting plate. This antenna is referred to as a large-current radiator (LCR) antenna and when driven by a current it radiates outwards on the surface of the plate. [0019] FIG. 1 h shows a driver circuit 206 for such an LCR transmit antenna 208 . The antenna is driven by an H-bridge comprising four MOSFETs 210 controlled by left (L) and right (R) control lines 212 , 214 . By toggling line 214 high then low whilst maintaining line 214 low an impulse doublet (that is a pair of impulses of opposite polarity) of a first polarity is transmitted, and by toggling line 212 high then low whilst holding line 214 low an impulse doublet of opposite polarity is radiated. The antenna only radiates whilst the current through it changes, and transmits a single gaussian impulse on each transition. [0020] FIGS. 2 a to 2 h show some examples of UWB waveforms, FIG. 2 a shows a typical output waveform of a UWB impulse transmitter, and FIG. 1 b shows the power spectrum of the waveform of FIG. 2 a . FIG. 2 c shows a wavelet pulse (which when shortened becomes a monocycle) such as might be radiated from one of the transmitters of FIGS. 1 b to 1 d . FIG. 2 d shows the power spectrum of FIG. 2 c . FIG. 2 e shows an impulse doublet and FIG. 2 f the power spectrum of the doublet of FIG. 2 e . It can be seen that the spectrum of FIG. 2 f comprises a comb with a spacing (in frequency) determined by the spacing (in time) of the impulses of the doublet and an overall bandwidth determined by the width of each impulse. It can also be appreciated from FIGS. 2 e and 2 f that dithering the pulse positions will tend to reduce the nulls of the comb spectrum. FIG. 2 g shows examples of basis impulse doublet waveforms for a logic 0 and a logic 1 FIG. 2 h shows an example of a TDMA UWB transmission such as might be radiated from the transceiver of FIG. 1 g , in which bursts of Code Division Multiple access (CDMA)-encoded data are separated by periods of non-transmission to allow access by other devices. [0021] Ultra wideband communications potentially offer significant advantages for wireless home networking, particularly broadband networking for audio and video entertainment devices, because of the very high data rates which are possible with UWB systems. However, UWB communications also present a number of special problems, most particularly the very low transmit power output imposed by the relevant regulatory authorities, in the US the FCC. Thus the maximum permitted power output is presently below the acceptable noise floor for unintentional emitters so that a UWB signal effectively appears merely as noise to a conventional receiver. This low power output limits the effective range of UWB communications and there is therefore a need to address this difficulty. [0022] One way to improve the range of a UWB communications link is to adopt a rake receiver type approach to combine the energy in a plurality of multipath components of a received signal. Multipath effects arise when a signal from a transmitter to a receiver takes two or more different paths (multipaths) such as a direct path between a transmit and receive antenna and an indirect path via reflection off a surface. In a multipath environment two or more versions of a transmitted signal arrive at the receiver at different times. Most wireless environments, and in particular indoor environments, have significant levels of multipath which, in a conventional RF communications system, typically produces a comb-like frequency response, the multiple delays of the multipath components of the received signal giving the appearance of tines of a rake. The number and position of multipath channels generally changes over time, particularly when one or both of the transmitter and receiver is moving. [0023] It is helpful to briefly review the operation of a conventional rake receiver before going on to consider a known UWB rake-type receiver. [0024] In a spread spectrum communication system a baseband signal is spread by mixing it with a pseudorandom spreading sequence of a much higher bit rate (referred to as the chip rate) before modulating the rf carrier. At the receiver the baseband signal is recovered by feeding the received signal and the pseudorandom spreading sequence into a correlator and allowing one to slip past the other until a lock is obtained. Once code lock has been obtained, it is maintained by means of a code tracking loop such as an early-late tracking loop which detects when the input signal is early or late with respect to the spreading sequence and compensates for the change. Alternatively a matched filter may be employed for despreading and synchronisation. [0025] Such a system is described as code division multiplexed as the baseband signal can only be recovered if the initial pseudorandom spreading sequence is known. A spread spectrum communication system allows many transmitters with different spreading sequences all to use the same part of the rf spectrum, a receiver “tuning” to the desired signal by selecting the appropriate spreading sequence (CDMA—code division multiple access). [0026] One advantage of conventional spread spectrum systems is that they are relatively insensitive to multipath fading. A correlator in a spread spectrum receiver will tend to lock onto one of the multipath components, normally the direct signal which is the strongest. However a plurality of correlator may be provided to allow the spread spectrum receiver to lock onto a corresponding plurality of separate multipath components of the received signal. Such a spread spectrum receiver is known as a rake receiver and the elements of the receiver comprising the correlator are often referred to as “fingers” of the rake receiver. The separate outputs from each finger of the rake receiver are combined to provide an improved signal to noise ratio (or bit error rate) generally either by weighting each output equally or by estimating weights which maximise the signal to noise ratio of the combined output (“Maximal Ratio Combining”—MRC). [0027] FIG. 3 a shows the main components of a typical rake receiver 300 , A bank of correlators 302 comprises, in this example, three correlators 302 , 302 and 302 each of which receives a CDMA spread spectrum signal from input 304 . The correlators are known as the fingers of the rake; in the illustrated example the rake has three fingers. The CDMA signal may be at baseband or at IF (Intermediate Frequency). Each correlator locks to a separate multipath component which is delayed by at least one chip with respect to the other multipath components. More or fewer correlators can be provided according to a quality-cost/complexity trade off. The despread output from a correlator is a signal with a magnitude and phase modified by the attenuation and phase shift of the multipath channel through which the multipath component locked onto by the finger of the rake receiver has been transmitted. A channel estimate comprising a complex number characterising the phase and attenuation of the communications channel, in particular for the multipath component of the channel the rake finger has despread, may be obtained, for example using a training sequence. The channel estimate may then be conjugated to invert the phase (and optionally normalised) and used to multiply the received signal to compensate for the channel. [0028] The outputs of all the correlators go to a combiner 306 such as an MRC combiner, which adds the outputs in a weighted sum, generally giving greater weight to the stronger signals. The weighting may be determined based upon signal strength before or after correlation, according to conventional algorithms. The combined signal is then fed to a discriminator 308 which makes a decision as to whether a bit is a 1 or a 0 and provides a baseband output. The discriminator may include additional filtering, integration or other processing. The rake receiver may be implemented in either hardware or software or a mixture of both. [0029] The effects of multipath propagation on UWB transmissions are not the same as on conventional RF transmissions. In particular where a UWB signal comprises a succession of wavelets or pulses (the terms are used substantially synonymously in the specification), because of the short duration and relatively long separation (in time) of these pulses it is often possible to substantially time-resolve the pulses belonging to multipath components of the UWB signal. In simple terms, the delays between the arrival of pulses in different multipath components originating from a single transmitted UWB pulse are often long enough to make it unlikely that two pulses arrive at the same time. This is described further below and can be exploited to advantage in a UWB receiver design. [0030] It is known to apply conventional rake receiver techniques to UWB communications systems, as described for example in WO01/93441, WO01/93442, and WO01/93482. FIG. 3 b , which is taken from WO01/93482, shows such a transceiver; similar arrangements are described in the other two specifications. [0031] Referring to FIG. 3 b , this shows a UWB transmitter 7 0 , 21 , 17 , 23 , 25 , 27 , 1 and a UWB receiver 1 , 27 , 3 , 29 , 31 , 1-N , 7 1-N , 9 . The receiver comprises a plurality of tracking correlators 31 1 - 31 N together with a plurality of timing generators 7 1 - 7 N , and as described in WO'482 (page 15) during a receive mode of operation the multiple arms can resolve and lock onto different multipath components of a signal. By coherent addition of the energy from these different multipath signal components the received signal to noise ratio may be improved. However the design of '482 is relatively physically large, expensive and power hungry to implement and fails to take advantage of some aspects of UWB multipath transmission. SUMMARY OF THE INVENTION [0032] In one aspect the invention provides an ultra wideband (UWB) receiver system comprising a receiver front end to receive a UWB signal; an analogue-to-digital converter coupled to said receiver front end to digitise said received UWB signal; and a correlator coupled to said analogue-to-digital converter to correlate said digitised UWB signal with a reference signal. [0033] Digitising the received UWB signal prior to correlation with a reference signal helps to reduce the cost, size, and power consumption of the receiver by facilitating further processing in accordance with a number of digital techniques as described below. For example one digital correlator correlating a pair of signals (the received and reference signals) may be employed to correlate a received pulse having a plurality of multipath components, rather than a separate correlation being needed for each separate multipath component. Correlation speed may also be increased by correlating a set of digitised samples of an incoming UWB signal with a reference signal. More generally digitising prior to the correlator facilitates time multiplexing of a correlator, for example storing partial or intermediate correlation results, and thus facilitates the provision of a much larger number of correlators than might otherwise be possible, thus helping to provide an improved signal to noise ratio. Multiple correlators may be employed in parallel, for example for pipelined correlation operations, and by multiplexing correlators in the time domain, sharing a single correlator between different multipath components of the same pulse and/or between different pulses a plurality of logically parallel correlators may be provided by a single physical correlator. In a preferred embodiment the UWB signal is a carrierless signal comprising a plurality of pulses or wavelets, thus facilitating such time multiplexing since much of the reference wave form is then substantially zero, comprising short pulses separated by longer periods of substantially zero signal, providing spaces in which a correlator or multiple-accumulator may be multiplexed for use in correlating other (later or earlier) transmitted pulses. Thus the correlator can be faster, more efficient, smaller and potentially cheaper. [0034] As UWB signals by their nature have a very wide bandwidth, for example 500 MHz or greater even when the UWB spectrum is subdivided into bands, the analogue-to-digital converter preferably operates at 10 9 samples per second and may operate at 10 10 samples per second or more. Since such fast analogue-to-digital conversion can have a high power consumption the reference signal, for example from a reference signal generator, may be used to control a power supply to the converter so that the power consumption of the converter can be reduced in periods where there is no expected received signal (pulse). Thus the converter may be inhibited or its power effectively removed during periods when no multipath component of a pulse is expected. Thus in another aspect the invention provides a method of controlling an analogue-to-digital converter in accordance with these techniques. [0035] As the received UWB signal may be at a very low level or even in the noise (because there may be redundancy in the transmitted data, for example by distributing a data bit over a plurality of successively transmitted pulses) an analogue-to-digital converter with a multiple bit resolution is indicated. However the number of bits required may be reduced by employing a controllable gain device such as a switched or programmeable attenuator prior to the analogue-to-digital converter and controlling this using the reference signal. Thus when a low level multipath component is expected the gain may be increased or attenuation reduced. In some circumstances a one bit analogue-to-digital converter may even be employed, which simplifies later correlation since a one-bit multiply may be implemented by means of an EXOR gate. Optionally one or more statistical characteristics of the received UWB signal may be monitored in order to adjust the signal prior to digitisation. [0036] Where the UWB signal comprises a plurality of pulses a plurality of correlation or multiply-accumulate modules may be employed to perform a plurality of correlations substantially in parallel between the digitised UWB signal and differently delayed versions of the reference signal to locate a pulse. As described further below in embodiments it is highly advantageous to delay the reference signal rather than the digitised sample data as using a look-up table in memory it is relatively straightforward to generate differently delayed versions of a stored signal. In embodiments this provides much faster signal acquisition and tracking than a conventional sliding window or early-late approach thus facilitating managing the very fast stream of data from the analogue-to-digital converter. The skilled person will appreciate that the bandwidth of the digital ‘pipe’ from this converter is roughly three orders of magnitude wider than the level at which conventional digital RF processing generally takes place (10 GHz as compared with 10 MHz). [0037] In preferred embodiments each of the correlation modules correlates a plurality of multipath components of a transmitted pulse and where these interleave but do not substantially overlap a correlation module may be time multiplexed to correlate multipath components of successively transmitted pulses with the reference signal. This further facilitates rapid processing of the digitised incoming UWB signal. Where correlation is performed against a plurality of multipath components a single template may be used for all multipath components but preferably a separate template is used for at least some of or each of the multipath components for improved correlation with the received signal. The reference signal template for one or more multipath components may be derived by training the receiver. For example an associated UWB transmitter may be employed to directly transmit a signal to the receiver to calibrate out or at least compensate for phase and/or gain distortions or non-linearities introduced by the receiver (analogue) front end and/or analogue-to-digital converter. This is important in a UWB system since the ultra wideband input stage will generally have phase and gain characteristics which vary significantly over the receiver bandwidth thus introducing significant distortions to the transmitted pulse shape. The associated transmitter may provide a timing signal directly to the receiver, for example across a direct wired connection, so that the receiver knows when to store received data into a reference signal memory in order to construct a receive signal template. A second training stage may optionally (but preferably) also be applied in which a signal from a remote transmitter is acquired using the stored reference signal and then used to store a second reference signal which takes account of the distortions introduced by the channel for each multipath component. [0038] It will be appreciated that the above described correlator may be employed to locate the position of a pulse in time (pulse-position modulation). However in preferred embodiments the correlator includes a discriminator which may be employed to determine the phase of a received pulse, for example determining whether the pulse is upright or inverted (bi-phase modulation). This bi-phase determination effectively comes at no extra cost to the pulse position determination and is effectively co-determined with the pulse position. This permits a doubling in the number of data bits to be sent as compared with either pulse position modulation or bi-phase modulation when used separately. Although it is known to dither the position of bi-phase pulses, for example using a pseudorandom sequence, it has not previously been recognised that a pulsed UWB signal may be modulated with information data to be communicated across a UWB link using pulse position modulation (PPM) in which a pulse position is dependant upon the information data and at the same time bi-phase modulation (or M-ary phase modulation) in which the pulse phase is also dependant upon the information data, two or more information bits being encoded as a combination of pulse phase and pulse position. [0039] Preferably the analogue-to-digital converter comprises a plurality of A-to-D conversion modules to provide a plurality of successively delayed samples of the UWB signal substantially in parallel, for example using a phase-tapped clock. The correlator may then be configured to process these successively delayed samples substantially simultaneously to allow a time-slice of the received signal to be correlated with a time-slice of the reference signal, preferably the time-slice having sufficient duration to encompass a substantial portion of a pulse within the UWB signal. Since a single transmitted pulse is generally received as a set of multipath components each comprising a version of the pulse the time-slice preferably extends over the duration of a pulse of a multipath component rather than over the entire set of multipath components which may be significantly delayed with respect to one another. A correlator to correlate time-slices of the received and reference signals each comprising a plurality of samples may comprise a plurality of multipliers in parallel coupled to a common accumulator. [0040] The reference signal is preferably provided from a reference signal memory, and advantageously within this memory the reference signal may be stored as a set of pulse shapes each separated by a delay, each pulse shape representing an expected pulse shape of a received multipath component of a transmitted pulse. Thus in a preferred embodiment the reference signal memory stores sets of data samples defining pulse shapes and associated data values defining delays between these pulses, that is between the reception of different multipath components of a pulse. [0041] Preferably the reference signal memory is configured to provide a plurality of stored reference signal values for different, successively delayed versions of the reference signal substantially simultaneously. This facilitates rapid location of the exact position in time of a multipath component of a pulse since the successively delayed versions of the pulse may be correlated with the incoming received signal in parallel. Thus the reference signal memory preferably has a plurality of outputs so that when the memory is addressed each of these outputs can provide a data sample corresponding to a different point on the stored reference signal waveform. In fact, as described above, it is preferable for the reference signal memory to have a plurality of sets of outputs each set of outputs providing a time-slice of samples of the stored reference signal extending over a period approximately equal to or greater than the duration of a multipath component of a pulse, the sets of samples being successively delayed to provide, in effect, successively delayed pulse shapes. It is further preferable that the delay of each set of samples, that is of each pulse shape, should correspond to an integral number (such as one) sample periods so that these successively delayed sets of samples may be provided by appropriate wiring of outputs from the memory. For example first and second sets of 16 samples delayed by one sample will have 15 sample values in common and need only 17 outputs from the memory to provide 32 sets of samples defining two pulse shapes delayed by one sample with respect to one another. [0042] Preferably the receiver system also includes a controller for identifying data in a received UWB signal which can be written into the reference signal memory for use as a template in later correlations. This facilitates training of the receiver to perform correlations with unexpected received UWB signal rather than an ideal UWB signal. It will be appreciated that the controller need not itself read the digitised signal to be used as a template but need only identify which portion of an incoming signal may be employed for this purpose, for example using the correlator. In some embodiments more than one reference signal may be stored. For example a reference signal may be stored for each of a plurality of transmitters from which the receiver system receives signals, allowing a different reference signal to be employed for each transmitter, and therefore allowing the receiver to compensate for the potentially different multipath channel to each transmitter. The reference signal for a transmitter may then be selected according to which transmitter the receiver is communicating with (or in some embodiments correlations with more than one reference signal may be performed effectively in parallel, for example by multiplexing). [0043] In a related aspect the invention provides an ultra wideband (UWB) receiver system for reception of UWB signals from a plurality of UWB transmitters, the receiver system comprising: a receiver front end to receive a said UWB signal; a correlator coupled to said receiver front end to correlate said UWB signal with a reference signal; and means to select one of a plurality of said reference signals for receiving a signal from a corresponding one of said transmitters. [0044] The above described features and aspects of the invention may advantageously be combined and permuted, as will be understood by the skilled person. BRIEF DESCRIPTION OF THE DRAWINGS [0045] These and other aspects of the present invention will now be further described, by way of example only, with reference to the accompanying figures in which: [0046] FIGS. 1 a to 1 h show, respectively, a typical UWB transceiver, a first example of a carrier-based UWB transmitter, a variant of this first example transmitter, a second example of a carrier-based UWB transmitter, a third example of a UWB transmitter, a receiver for the third example transmitter, a UWB transceiver employing spread spectrum techniques, and a driver circuit for a large-current radiator antenna; [0047] FIGS. 2 a to 2 h show examples of UWB waveforms; [0048] FIGS. 3 a and 3 b show, respectively, the main elements of a conventional rake receiver for spread-spectrum signals, and a block diagram of a known UWB transceiver employing conventional rake receiver techniques; [0049] FIGS. 4 a to 4 d show, respectively, a transmitted UWB signal comprising a single pulse, an example of a received version of the transmitted pulse of FIG. 4 a with multipath reflections and other propagation effects, a series of transmitted UWB pulses of the type shown in FIG. 4 a , and a received signal corresponding to the transmitted signal of FIG. 4 c showing overlapping multipath reflections; [0050] FIG. 5 shows an overview block diagram of a UWB receiver embodying aspects of the present invention, [0051] FIG. 6 shows a simplified block diagram of a demodulator architecture for use with the receiver of FIG. 5 ; [0052] FIG. 7 shows a timing diagram illustrating timing variations of multipath components of a pulse with respect to pulse repetition frequency; [0053] FIG. 8 shows diagrammatically a modulation scheme for use with the D modulator of FIG. 6 , [0054] FIGS. 9 a and 9 b show, respectively, a data frame format and pilot tone pulses for the receiver of FIG. 5 ; [0055] FIGS. 10 a and 10 b show, respectively, a UWB transmitter and a pulse generator for the UWB transmitter; [0056] FIGS. 11 a and 11 b show, respectively, a signal acquisition and tracking system for the receiver of FIG. 5 , and a waveform memory data format; [0057] FIGS. 12 a and 12 b show, respectively, a flow diagram of a signal acquisition procedure, and a diagrammatic illustration of a signal hunt process; [0058] FIGS. 13 a and 13 b show, respectively, a reference waveform generation system, and a variant of the system of FIG. 13 a; [0059] FIG. 14 shows a block diagram of a correlator for the demodulator of FIG. 6 ; [0060] FIGS. 15 a and 15 b show, respectively, received signals with interleaved multipath components, and a diagrammatic illustration of the operation of the correlator of FIG. 14 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0061] As previously mentioned a transmission medium coupling a UWB transmitter and UWB receiver will typically give rise to a number of physical effects that complicate the function of the receiver. The transmission medium may comprise a wireless or wired transmission channel. The physical effects include multiple path reflections, which result in multiple pulses at the receiver or each transmitted pulse, in some cases these pulses being phase inverted. Dispersion, frequency dependent continuation and other properties of the transmission medium distort the pulse shape. Interference and noise sources are received in addition to the desired pulse data. Noise sources include thermal noise (from the receiver itself), narrow band interference from radio transmitters sharing the same frequency spectrum, and broadband interference (from switching and alike). There may also be interference from co-located UWB systems sharing the same physical space for electrical cabling. A UWB receiver should preferably be capable of dealing with all these effects. [0062] Referring now to FIG. 4 , FIG. 4 a shows an example of a transmitted UWB pulse, which in this example has a duration of approximately 100 ps. FIG. 4 b shows the same pulse as it might be seen by a UWB receiver. As can be seen the received pulse has a plurality of multipath components and also exhibits distortion and other propagation effects. Multipath components are received over a time scale which depends upon the transmission channel but which may, for example, be between 10 ns and 100 ns (the pulses shown in this diagram are not to scale), multipath at the longer end of this range being observed in wired systems such as UWB over mains (AC power cable) transmissions as described in the co-depending UK Patent Application No. 0222828.6 filed on 2 nd Oct. 2002. The first received multipath component need not be the largest (as shown in FIG. 4 b ) and may be significantly distorted or even inverted. [0063] FIG. 4 c illustrates a series of transmitted pulses and FIG. 4 d an example of a corresponding received signal. It can be seen that multipath reflections from one pulse may overlap with the first signals from the next pulse. This problem is exasperated when timing modulation is applied to a transmitted pulse. [0064] FIG. 5 shows a block diagram of a UWB receiver 500 embodying an aspect of the present invention. [0065] An incoming UWB signal is received by an antenna 502 , which may comprise a capacitive an/or inductive coupling to a cable system such as a mains power cable or a telephone cable. The received UWB signal is provided to an analog front end block 504 which comprises a low noise amplifier (LNA) and filter 506 and an analog-to-digital converter 508 . A set of counters or registers 510 is also provided to capture and record statistics relating to the received UWB input signal. The analog front end 504 is primarily responsible for converting the received UWB signal into digital form. [0066] The digitised UWB signal output from front end 504 is provided to a demodulation block 512 comprising a correlator bank 514 and a detector 516 . The digitised input signal is correlated with a reference signal from a reference signal memory 518 which discriminates against noise and the output of the correlator is then fed to the defector which determines the n (where n is a positive integer) most probable locations and phase values for a received pulse. [0067] The output of the demodulation block 512 is provided to a conventional forward error correction (FEC) block 520 . In one implementation of the receiver FEC block 520 comprises a trellis or Viterbi state decoder 522 followed by a (de) interlever 524 , a Reed Solomon decoder 526 and (de) scrambler 528 . In other implementations other codings/decoding schemes such as turbo coding may be employed. [0068] The output of FEC block is then passed to a data sychronisation unit 530 comprising a cyclic redundancy check (CRC) block 532 and de-framer 534 . The data sychronisation unit 530 locks onto and tracks framing within the received data separating MAC (Media Access Control) control information from the application data stream(s) providing a data output to a subsequent MAC block (not shown). [0069] A control processor 536 comprising a CPU (Central Processing Unit) with program code and data storage memory is used to control the receiver. The primary task of the control processor 536 is to maintain the reference signal that is fed to the correlator to track changes in the received signal due to environmental changes (such as the initial determination of the reference wave form, control over gain in the LNA block 506 , and on-going adjustments in the reference wave form to compensate for external changes in the environment). [0070] Referring now to the analog front end 504 in more detail, in a preferred arrangement the LNA block 506 amplifies the signal received from the antenna or cable coupling. The amplifier design contains a fixed frequency passive filter that rejects signals out side of the FCC/ETSC permitted spectral band (3.1-10.6 GHz), as well as rejecting signals from the 5 GHz UNII frequency band. Rejection of such signal areas prevents strong narrow band transmissions from saturating the subsequent A/D converter. It is particularly important to reject signals that are likely to be co-located with a UWB device, such as 802.11, Bluetooth and mobile phone frequencies. [0071] The LNA also contains a switchable attenuator that may be used to adjust the signal level fed to the A/D unit. The attenuator may be controlled directly by both the control processor 536 and the reference signal. The purpose of the attenuator is to avoid input saturation at the A/D unit, while maintaining sufficient sensitivity to detect the received pulse waveform. [0072] The reference waveform from the Detector unit may also control the attenuation in real time, allowing different gain settings to be applied to different portions of the multipath signals that are received from a single pulse. The A/D converter 508 may take a variety of forms. In a preferred embodiment the A/D converter 508 is logically configured as a continuous sampler, effectively providing a continuous stream of samples at a suitable rate as determined by the upper frequency of the relevant UWB band and the Nyqust criterion, for example 20G samples per seconds (20 GHz) for a 10 GHz upper frequency. Physically, however, the A/D module may comprise a bank of samplers, for example 16 to provide 16 samples for each received pulse, successively triggered by a phase tapped clock to provide a snapshot of a portion of a received UWB signals at different phases which may then be used to provide an input to the correlator banks 514 of demodulation block 512 . In this way parallel blocks of signal samples may be provided at a rate of a few hundred megahertz, for example at substantially the pulse repetition frequency (PRF) rate thus effectively reducing the primary digitisation clocks speed to this rate; preferably each block substantially spans the duration of a received UWB pulse. Implementing the sampler as a plurality of parallel sampling circuits operating of a phase tapped reference clock facilitates the fabrication of suitable sample (and hold) devices on conventional silicon processors. [0073] Some examples of fast A/D converters are the described in the following documents, which are hereby incorporated by referenced: “A 20GSamples/s 8-Bit A/D Convertor with a 1 MB memory in 0.18 μCMOS presented by Brian Setterberg of Agilent Technologies, Inc., at the 2003 IEEE International Solid-State Circuit Conference (ISSCC)”; “A Serial-Link Transceiver Based on 8 -Gsamples/s A/D and D/A Converters in 0.25 μm CMOS presented by Chih-Kong Ken Yang, Vladimir Stojanovic, Siamak Modjtahedi, Mark A, Horowitz and William F. Ellersick, IEEE Journal of Solid-State Circuits, Vol 36, No 11 , Nov. 2001”; published US Patent Applications 2002 0167373 and 2002 0145484. [0074] Depending upon the application the A/D converter may either be a single-bit converter or a multi-bit converter, and may either monitor the received voltage level or the power level in the received signal. The A/D converter 508 may comprise a non-continuous sampler where the sampler is run only around the expected time of arrival of a received pulse (or around a desired time slice when hunting for a received pulse) and is substantially inactive at other times. In this way a high sampling rate may effectively be achieved but with advantages such as reduced power consumption. [0075] In general, it is desirable to gain as much information about the input signal as possible, favouring a multi-bit voltage sensitive sampling scheme. However, implementation constraints (physical silicon area and power consumption) mean that such a scheme is preferably only used for devices where immunity to noise (including unexpected narrow band interference) is important, for example where operation in close proximity to an 802.11 system is envisaged. In some arrangements sure bit conversion permits an acceptable compromise. [0076] Non-continuous sampling can offset some of the disadvantages of such a sampler, but can constrain the range of possible delay modulation values that can be detected, thereby reducing the potential information that can be carried by each pulse. Such a trade-off is often acceptable in systems where there are many co-located independent pulse transmissions, since the risk of ‘collisions’ between pulses from different transmissions is reduced. [0077] Single bit sampling is prone to saturation but offers a significant saving in silicon cost and power consumption and is therefore preferable level based A/D converters benefit from accurate control the input signal gain. The AFE 504 therefore preferably contains counters that monitor statistics of the input signal conversion, recording the number of values recorded in each of the sampling levels over some period of time. Software running on the Control Processor periodically reads these values and resets the counters. The software may then use these to determine an optimium setting for the gain/attenuation control applied to the received signal by LNA unit 506 . For such purposes, the software may assume that the received signal is, on average, a gaussian noise signal. [0078] Referring now to the demodulator block 512 , this is responsible for extracting a data signal imposed on the pulses by a transmitter. [0079] The scheme described here is specifically designed to decode modulation by means of the pulse arrival time or by the pulse phase. It may also be adapted to detect modulation by means of the pulse shape (spectral modulation). [0080] The input to the demodulator is a stream of sample data from the AFE 504 ; the output is a stream of decoded data bits. The output data rate is substantially constant fixed by the PRF (Pulse Repetition Frequency) and the number of bits encoded by each pulse. The operating parameters of the demodulator (PRF and bit-encoding) are typically fixed for a given transmitter. However, the demodulator (and other system parameters, such as AFE gain) may be time multiplexed by the MAC processor in order to facilitate near simultaneous reception from multiple transmitters. [0081] The demodulator contains units to correlate the received signal against a reference signal (programmed and maintained to track changes in the external signal propagation environment) by control processor 536 . The detailed form of the demodulator is shown in FIG. 6 . [0082] Referring to FIG. 6 , this shows a simplified block diagram of demodulator 512 of FIG. 5 ; like elements to those of FIG. 5 are indicated by like reference numerals. The input from the wireless antenna or wired interface and amplifier/filter unit 506 is implemented in discrete analog circuitry, and the A/D (sampler) 508 and demodulator 512 are implemented in the sampling clock domain which has, in one embodiment, an effective range of 25 GHz, corresponding to an actual clock rate of 250 MHz. The system control logic and output to the forward error correction apparatus also operates at 250 MHz. [0083] The correlator 514 comprises a bank of multiply-accumulate units 600 each of which receives an input signal sample (comprising a set of samples of the input signal at successive sampling intervals) and multiplies this by a reference sample (comprising a set of samples of a reference waveform at successive sampling intervals) provided by reference waveform synthesiser 518 . In the case of single bit A/D sampling the multiplier operation may be implemented using a simple XOR gate. The accumulators average the (correlation) data over a number of pulses, by averaging over (successive) transmitted pulses bearing the same encoded data and/or averaging over multipath components. [0084] The reference signal generator or synthesiser 518 provides the reference signal to the multiply-accumulate units 600 under control of a pattern sequencer 602 . The pattern sequencer is controlled by a PSR (Pseudo Random) sequence lock acquisition module 604 , preferably implemented in software as described later. Conceptually the pattern sequencer 602 provides a reference waveform 606 to a plurality of delay units 608 to provide a plurality of successively delayed versions of the reference waveform to multiply-accumulate units 600 . However although illustrated as a pipeline system with multiply-accumulated delay taps equivalent to a sample period to reduce the effective clock speed the reference waveform is preferably applied in parallel to the multiply-accumulate units 600 as described later. Such a parallel implementation is possible because the reference waveform is stored in memory and therefore a parallel set of differently delayed reference waveforms may be read out from the memory substantially simultaneously; implementation of the demodulator would be significantly more complex were delay taps conceptually applied to the incoming received UWB signal sample data since without additional complexity this would not be readily available in the form of successively delayed time windows of samples of parallel in samples. [0085] The reference signal for the correlator is programmed into the reference signal generator 518 by software running on control processor 536 , which preferably uses a training algorithm to determine the receiver response (that is, amptitude and phase distortion to a transmitted pulse). The control processor 536 also maintains a clock phase locked to the PRF (Pulse Repetition Frequency) of the transmitter from which signals are being received by using the arrival times of detected pulses relative to an internal timing reference (Local Crystal Oscillator). A power control output 610 from the reference waveform generator may also be employed to gate power to the A/D and sampling circuitry 508 to put this circuitry into a reduced power mode in periods where there is no expected received signal. This is particularly advantageous in systems using a multi-bit A/D since these often have a relatively large power consumption. [0086] A multiply-accumulate unit 600 provide outputs to a discriminator 612 which determines the sign and peak value (or values if probabilistic outputs are supplied to the following stage of the (absolute) value maximum accumulator output). The discriminator outputs provide an output data signal identifying the position of a received pulse and the pulse phase (that is, normal or inverted). A constellation decoder maps this position/phase data from the discriminator to an n-bit symbol which is then passed to the forward error correction block 520 . [0087] The demodulator 512 has a plurality of interfaces to other parts of the receiver system, each of which is preferably via a data synchroniser 616 a, b, c , such as a register or buffer. Thus the multiply-accumulate units 600 provide an output to the control processor 536 for calibration of the receiver front end (and preferably also the transmission channel) and for location processing to facilitate physical location of a UWB receiver according to known techniques. The interface between the constellation decoder 614 and FEC blocks 520 is preferably also implemented via a buffer. The PSR lock acquisition module 502 preferably has a bi-directional interface to a software control function implemented on control processor 536 to provide functions such as physical location of the receiver, delay tracking, and data (de) whitening. [0088] Referring next to FIG. 7 this shows relative timings of transmitted data pulses and multipath components of such pulses as seen by the receiver. As can be seen from FIG. 7 a typical delay span for a multipath reflection is between 1 and 100 ns whereas a typical interval between successive transmitted data pulses is between 2 and 10 ns. It can therefore be appreciated that a multipath reflection of a one pulse may arrive following a direct, line of sight transmission of the next pulse, or even of the next few pulses. The multipath reflections may also be phase inverted subject to different path distortions from the direct path. [0089] In a simple but less preferred arrangement the multiply-accumulate stages 600 of the correlator only integrate multipath energy over the inter-transmit pulse period so that, for example in FIG. 7 , multipath components arriving outside the 2-10 ns delay range would be ignored. However in general typical multipath delays are greater than the average inter-transmit pulse period, and thus significant energy may be lost with this approach. The problem is exacerbated if pseudo-random timing jitter is applied to the timing of the transmitted pulses to achieve spectral whitening. [0090] For these reasons it is therefore preferable to implement two or more correlator banks, that is banks of multiply-accumulate units 600 as shown in FIG. 6 , parallel to facilitate pipelining of the pulse integrations. Such parallelism implemented by repetition of the correlator logic but in a preferred arrangement this parallelism is achieved by multiplexing the use of a single set of multiply-accumulate chains 600 , for example by keeping track of distinct sets of accumulator values in a static RAM (Random Access Memory) buffer memory. [0091] FIG. 8 shows a schematic diagram of a UWB signal employing a preferred modulation scheme for the above described receiver and which may be generated by a transmitter described later with reference to FIG. 10 . The signal of FIG. 8 may be employed in a wireless or wired UWB transmission system. [0092] The signal 800 comprises a plurality of wavelets or pulses 802 each of which has either a normal or inverted form to encode a single bit of information data to be transmitted; FIG. 8 shows two normal (rather than inverted) examples of such pulses. As illustrated, according to a preferred such a wavelet or pulse comprises a positive-going portion 802 a and negative-going portion 802 b ; the order of these two portions may be reversed to invert the pulse, thus facilitating generation of normal and inverted pulses in hardware. The pulses 802 have a nominal pulse repetition frequency, for example of the order of 100 MHz. However an additional one or more information data bits may be modulated onto signal 800 by varying the precise position (timing) of a pulse dependent upon the data to be transmitted. For various reasons bi-phase modulation of a UWB signal has been the preferred modulation of many applications. However by also varying the pulse position more data may be encoded onto the UWB signal thus increasing the available data rate for the options for forward error correction at a given data rate and hence the range of a signal. In practical schemes it is further preferable to dither the pulse position (in time) in a deterministic manner to further whiten the UWB signal spectrum and hence reduce the overall signal profile and/or facilitate staying within regulatory boundaries. Thus in addition to the precise timing of a pulse being dependent upon variable information data to be transmitted the pulse position may also be dependent upon a pseudo random or PN (pseudo noise) signal. Such a pseudo random sequence is preferably deterministic so that although apparently random once the sequence and start point is known it can be reconstructed in a deterministic manner at the receiver to allow this PN modulation to be effectively subtracted from the received signal or compensated for in other ways. [0093] Preferably the PN modulation is greater than the information data modulation since having a relatively small range of pulse positions about an expected pulse position (once the effects of PN modulation have been compensated for) simplifies demodulation of position-encoded data. In one preferred arrangement, described below, the positions a pulse can take in response modulation by information data are separated by one (or more generally an integral number) of reference (and input) UWB signal sampling intervals. Thus in some preferred embodiments a pulse 802 may take one of eight or 16 different positions in time (although other numbers of positions may be employed) and correlator 514 correlates the input signal with reference signals at all of these positions substantially in parallel to, in a parallel operation, locate the actual or most likely position of a received pulse. As shown in FIG. 8 according to a typical scheme the duration of a single doublet is typically between Sops and 100 ps and the correlator bank 514 performs parallel correlation operations over a time window 804 of approximately ins, thus identifying the pulse as being in one of around 16 overlapping positions. The skilled person will understand that the above timings, and the number of parallel multiply-accumulate units 600 of correlator 514 may be varied according to the requirements of a particular implementation or application. [0094] FIG. 9 a shows one example of an MAC frame 900 for use with the receiver 500 when receiving a signal of the type shown in FIG. 8 . This MAC frame is, however, provided merely for illustrative purposes and many other different frame formats may be employed. The example MAC frame 900 begins with a preamble sequence 902 comprising 32 bits of preamble data, for example pseudo random data for training. This is followed by a 4 byte header comprising a pseudo random sequence identifier and a pseudo random sequence seed (for identifying a starting point in a sequence), for example as a pair of 2 byte values. Different pseudo random sequences may be employed by different transmitters to help avoid collisions between transmitted UWB data signals. The header is preferably structured to give the appearance of noise, and may therefore include a whitening function—for example the pseudo random sequence identifier and seed may each be selected so that the header appears essentially random. The header is followed by payload data 906 which may also be whitened of a fixed or variable length, for example 128 bytes. [0095] FIG. 9 b schematically illustrates the positions of pilot tone pulses within a UWB signal 910 also comprising information-carrying pulses (not shown). In one arrangement one in every 100 pulses comprises a pilot tone pulse and, as can be seen from FIG. 9 b , these pilot tone pulses occur at regularly spaced intervals to provide a low-level pilot tone within the UWB signal regulatory spectral mask. Optionally the positions (in time) of the pilot tone pulses may be modulated to provide timing jitter, allowing more frequent or stronger pilot tone pulses within the spectral mask, although this is not necessary. [0096] FIGS. 10 a and 10 b illustrate an example of a UWB transmitter 1000 which may be employed to generate the information data modulated UWB signal 800 of FIG. 8 . The transmitter structure of FIG. 10 is provided by way of example only and other transmitter structures may also be employed to generate the UWB signal of FIG. 8 . For simplicity forward error coding arrangements are not explicitly shown in the figure. [0097] Referring to FIG. 10 a a clock 1002 operating at, for example, 250 MHz provides a clock signal to a chain of delay elements 1004 a - e each providing a delay of, in this example, 40 ps. The successively delayed versions of the clock signal are provided to each of a plurality of monostable pulse generators 1006 , each of which also receives an enable and control input from a controller 1008 . When enabled by the controller 1008 a monostable 1006 provides an output pulse doublet; the phase (normal or inverted) of the pulse doublet is also controllable by controller 1008 . The outputs from all of the monostable pulse generators 1006 are combined, in this example in summers 1008 and the combined output is provided to a transmit antenna 1010 . The controller 1008 receives a pseudo random sequence input from a pseudo noise generator 1012 , and also receives a data and control input 1014 , for example from a preceding forward error correction block and from a transmitter control processor. The data and control input receives information data to be transmitted by the transmitter and control signals such as a timing control signal to control when the transmitter is to transmit and/or pseudo noise sequence selection and start point control signals. The controller 1008 may comprise a state machine implemented in either software or dedicated hardware or a combination of the two. [0098] In operation the controller 1008 controls the timing of transmitted UWB pulses and the phase (normal or inverted) of these pulses by providing appropriate enable and phase control signals to the monostable pulse generators 1006 which are then triggered to provide output pulses at the corresponding time by the phase tapped clock from clock signal generator 1002 . [0099] Referring now to FIG. 10 b this shows an example of one implementation of a monostable 1006 for the transmitter of FIG. 10 a . The monostable comprises two pulse generators 1020 a, b , one providing a positive-going pulse, the other providing a negative-going pulse, outputs from these two pulse generators being combined in a summer 1022 to provide a pulse doublet output signal 1024 . Both of pulse generators 1020 a and 1020 b are controlled by a common enable line 1026 which when asserted enables the pulse generators to provide an output pulse in response to an input timing reference signal on line 1028 , but which when de-asserted disables the pulse generators from providing their outputs. In addition pulse generator 1020 b has a delay signal input 1030 which delays the production of its output pulse by two cycles to effectively invert the pulse doublet. Thus according to whether or not the delay input 1030 is asserted a pulse doublet comprising either a positive or negative-going pulse or a negative then positive-going pulse is provided. A UWB transmitter such as a transmitter 1000 of FIG. 10 may be combined with the UWB receiver of FIG. 5 to provide a UWB transceiver. In this case it is preferable that the UWB transmitter and receiver portions of the transceiver are synchronised to a common PRF clock to avoid self-collision, that is to avoid jamming reception of transmissions from a remote transmitter by local transmissions. [0100] Referring next to FIG. 11 , this shows details of the receiver 500 of FIG. 5 , and in particular details of the signal acquisition and locking system, including details of the reference signal capture signal. Like elements of those to FIGS. 5 and 6 are shown by like reference numerals. Broadly speaking the functions of the PSR lock acquisition module 604 are provided by a phase control processor and the functions of the pattern sequencer 602 of FIG. 6 are provided by a combination of a reference waveform data table and of a PSR sequence generator. [0101] As previously described the analog front end and A/D converter 504 provides a plurality of examples of a received UWB input signal in parallel to correlator 514 and each set of input signal samples is processed by a correlator comprising one of multiply-accumulate units 600 of correlator 514 to correlate the set of received samples in parallel with sets of reference signals representing differently delayed pulses. The sets of samples defining differently delayed versions of a referenced signal pulse are derived from a waveform of a pulse stored in a reference waveform data table 1100 . A reference received pulse is preferably stored in this table as a pulse shaped for each of a set of multi part components of the pulse together with data representing delay intervals between these multipath components, as shown in FIG. 11 b . However differently delayed versions of a pulse may be provided by accessing a common wave shape data store for the pulse. As shown in FIG. 11 b a reference or template waveform for a single received pulse having a plurality of multipath components comprises sample data 102 for a plurality of successive sample points of a multipath component of a pulse followed by delay data 1104 representing an interval between that multipath component of the pulse and the next multipath component. An input 1106 allows reference waveform data to be written into the referenced waveform data table 1100 . Reference waveform data is provided to the correlator 514 from the data table 1100 under control of a PSR sequence generator 1108 in synchronisms with a PRF clock input 1110 . [0102] A phase control processor 1112 provides a PRF clock to sequence generator 1108 and reference waveform data to data table 1100 . The phase control processor includes a processor and non-volatile program memory storing program code for pilot tone identification, to provide a software phase locked loop (PLL), for multipath component identification, and for template wave shape retrieval and storage. A clock 1114 provides a clock signal to the phase control processor and receives tracking data from processor 1112 comprising a time advance/retard signal for controlling the phase of the clock and a frequency increase/decrease for controlling the frequency of the clock when the phase needs to be consistently advanced/retarded. The clock 1114 is thus adjustable to track movement of the receiver with respect to the transmitter by means of systematic adjustment in the clock timing (which are generally small compared with the modulation). As described further below clock 1114 acts as a slave to a similar clock in a remote transmitter and thus acts as a link clock; typically it has a frequency in the range 50-200 MHz. [0103] The phase control processor 1112 provides a control output to a UWB transmitter 1116 , such as transmitter 1000 in FIG. 10 , to control the transmitter to provide a UWB signal from a transmit antenna 1118 for use in training receiver. The control processor 1112 also receives a starter frame input signal 1120 from a MAC state machine implemented in either hardware or software. The phase control processor 1112 further receives a set of inputs 1122 , one from each accumulator of correlator 514 , and a further input 1124 from the output of discriminator 612 . [0104] Broadly speaking, in operation the phase control processor 1112 programs the reference waveform data table 1100 with an initial, predetermined wave shape and then identifies the UWB signal pilot tone and runs a software phase lock loop to lock onto this tone to provide a time reference. The processor then uses this to identify the wave shape of a received pulse, including its multipath components. Optionally the processor 1112 may apply a Fast Fourier Transform (FFT) filter to remove narrow band interference. Broadly speaking to locate the multipath components of a transmitted pulse the phase control processor 1112 scans a sample window by shifting the phase of the PRF clock with respect to the internal clock from clock generator 1114 , integrating to obtain an average sampled data wave shape. Initially the multipath component with the strongest signal is identified and the shape of this multipath component of the pulse determined from the input data, and then the processor hunts for other multipath components both backwards and forwards from the strongest signal (because the direct line of sight pulse may not be the strongest). As previously described the correlator operates with blocks of eight or 16 samples and these blocks are effectively positional in time with respect to the link clock reference from clock generator 1114 . Preferably the multipath component pulse tracking procedure is repeated at a frequency in the order of kilohertz in order to track variations in the multipath channel and, in embodiments where implemented, to obtain physical location information relating to the receiver's position. In wired UWB transmission systems the multipath environment may be quasi static in which case a channel characterisation procedure such as that described above may only be applied at switch on or, for example, when the error rate increases above a threshold. [0105] In the arrangement shown in FIG. 11 a the phase control processor receives sampled input signal data via the correlator 514 . This simplifies the architecture of the receiver, although in other arrangements processor 1112 may receive sampled input signal data directly from analog front end 504 . To obtain sample input data from correlator 514 the input data may be correlated with a delta function such as a spike or impulse written into the wave form data table. [0106] FIG. 12 a shows a flow diagram explaining further the operation of the phase control processor 1112 of FIG. 11 a . To initial calibrate the receiver front end the control processor, at step S 1200 , instructs transmitter 1116 to local UWB pulses under control of the local clock generator 1114 . These pulses are received at a very high signal level and, moreover, processor 1112 knows when these pulses are transmitted and thus knows at what position in time the received input data is expected to comprise a transmitted pulse (taking account of the delay introduced by the separation between transmit antenna 1118 and receive antenna 502 (typically one or a few centimetres)). [0107] At step S 1202 processor 1112 programs wave form data table 1100 with a predetermined template, in particular an impulse, and hunts for the transmitted pulses by controlling the timing of PSR sequence generator 1108 . This is conveniently performed by inhibiting generation of a pseudo random sequence so that the phase of the output of generator 1108 may be varied by using the PSR seed as a phase offset adjust. Once the locally transmitted pulses are identified the wave shape of a pulse as received and digitised by analog front end 504 is read from correlator 514 and written into the referenced wave form data table to serve as an initial reference wave form. This in effect calibrates out phase and gain non-linearities in the receiver front end. Although the locally received signal is strong the wave shape data written into the data table 1100 may optionally comprise an average of a plurality of received pulses. [0108] Once this initial calibration has been performed the phase control processor 1112 has the more difficult task of frequency and phase locking onto a signal from a remote transmitter and of tracking this signal. Thus at step S 1206 processor 1112 controls the receiver to hunt for a signal at the pulse repetition frequency of the remote transmitter, that is at the pilot tone of the remote transmitter. The pilot tone frequency may not be known exactly but in preferred arrangements is limited to a small set of possible frequencies such as 50 MHz, 100 MHz, and 250 MHz and thus the receiver can pick each of these frequencies in turn to look for incoming UWB signals. The process of hunting for a signal at PRF is illustrated in FIG. 12 b . The receiver system first runs a correlation in a set of windows 1210 spaced by intervals at the PRF frequency, averaging the correlation results over a plurality of such windows and, if no significant correlation is found, slips the windows, at the same frequency, to a slightly delayed position 1212 as shown in timeline (ii) to repeat the correlation and averaging procedure until pulses at the PRF are found. Once the PRF frequency has been found, because the correlator 514 provides a plurality of outputs corresponding to a small range of delays either side of a desired time position it is straightforward to track variations in the PRF. The clock generator 1114 (and the equivalent in the transmitter) is preferably crystal controlled and thus relatively stable and varies only slowly compared with the kilohertz PLL tracking frequency. The more difficult task is to locate the remote transmitter PRF in the first place, particularly as a pilot tone pulse is transmitted for of the order of only one in 100 pulses, and because the UWB signal is relatively low level, especially at longer ranges. These difficulties are addressed by averaging over a relatively long period in order to identify the systematic pilot tone impulses which appear at fixed times and distinguish, for example, from other UWB pulses which appear effectively at random times. Depending upon the strength of the UWB signal and upon the range and transmit channel it may take as long as one or a few seconds to lock onto the relevant pilot tone as the correlator windows are slipped, which allows averaging over extremely large number of pulses. [0109] Once the phase control processor has locked onto the PRF of the remote receiver the processor can rely on the relative stability of clock generator 1114 and can thus rewrite the referenced wave form data table 1100 with an impulse and average over a plurality of pulses, typically between 100 and 1000 pulses, to determine the reference wave form for the transmit channel, and can then write this into the wave form data table. The number of pulses over which the signal needs to be averaged depends upon the range—one pulse may be enough at one metre and average of 10 4 pulses may be necessary at a range of 30 metres. Once the reference wave form for a first multipath component of a transmitted pulse has been identified the phase control processor 1112 can hunt backwards and forwards from this to identify the next multipath component of the pilot tone, and this can be repeated to determine data for a plurality of multipath components of a transmitted pulse. The number of multipath components for which data is acquired depends upon a trade off between acquisition time and system sensitivity (capturing energy from more multipath components facilitates greater sensitivity but takes longer to acquire). It will be appreciated that once the pulse shapes and delays for multipath components of a pulse have been located in time and samples stored tracking the variations of these over time is relatively straightforward and may be accomplished by periodically averaging over say 100 to 1000 pulses, for example by time multiplexing correlator in a similar way to that described below. [0110] FIG. 13 shows details of the reference wave form generation system. The PSR sequence generator 1108 receives control signals from the control processor 1112 comprising a pilot tone to control the timing of the reference wave form generation, and a starter frame signal and a sequence seed to control pseudo random sequence modulation for pulse position dithering, and provides a read timing control output 1302 to a pattern controller 1300 . Referring ahead to FIG. 15 a , this shows the received multipath components of two successively transmitted pulses 1500 and 1502 , each with a plurality of multipath components 1500 a - c , 1502 a - c . It can be seen that the multipath components 1500 a, b of pulse 1500 arrive before the start of pulse 1502 but that the multipath component 1500 c of pulse 1500 arrives between multipath components 1502 a and 1502 b of pulse 1502 . In order to correlate the received signal with a reference wave form corresponding to pulse 1500 (or 1502 ) the reference wave form data table 1100 should preferably be able to provide the appropriate multipath component of the pulses at the appropriate times even when these are interleaved as shown. Although this is not essential it is preferable in order to be able to retrieve energy from more multipath components of a received signal. [0111] Referring back now to FIG. 13 a pattern generator 1300 provides a plurality of outputs 1304 for providing reference wave forms corresponding to a plurality of transmitted pulses having overlapping multipath components. Thus, for example, if it is desired to process overlapping or interleaved multipath components from two successive transmitted pulses pattern controller 1300 provides two address outputs 1304 for addressing the wave form data table at appropriate times to provide portions of the reference wave form corresponding to the overlapping or interleaved portions of the multipath components. Thus referring again to the example of FIG. 15 a pattern controller 1300 provides a first address output for controlling data table 1100 to provide multipath components 1500 a, b, c and a second address output for addressing the table to provide the reference wave shapes for multipath components 1502 a, b, c at appropriate times. It will be appreciated that the number of address outputs of pattern controller 1300 depends upon the delay span of the number of significant multipath components of a pulse as compared with the inter-transmit pulse spacing. The reference wave form data table 1100 provides an output 1306 which comprises a time ordered combination of the multipath components of successfully transmitted components in the example of FIG. 15 a multipath components 1500 a , 1500 b , 1502 a , 1502 c , 1502 b and so forth. In a preferred arrangement a single set of outputs provides these multipath components in a time multiplexed fashion for use with correlator 514 also operating in a time sliced or multiplexed configuration. However an alternative arrangement is illustrated in FIG. 13 b in which data table 1100 has a plurality of sets of outputs, one for each transmitted pulse the receiver is concurrently able to process, which are combined in a summer 1310 and provided as a combined output for subsequent correlation. [0112] Referring in more detail to the parallel data outputs from the reference wave form data table, the data table memory is configured to provide a plurality of blocks of reference signal data in parallel, each block of data being delayed with respect to a previous block of data. A block of data may comprise, for example, eight or 16 sample values of the stored reference wave form, preferably defining a multipath component of a pulse such as a one of components 1500 a, b, c of FIG. 15 a . The blocks preferably overlap in time and in one arrangement each block is delayed from the previous block by one sample, 16 blocks defining 16 successfully delayed multipath pulse components being output in parallel. In this example this requires a BUS comprises 256 parallel outputs from reference output data table 100 , but the majority of these outputs may be provided simply by appropriate wiring since 16 blocks each of 16 samples, each delayed by a sample requires only 32 parallel sample value outputs. Each of these sample value outputs, it will be appreciated, may comprise a single or multi-bit value, depending upon whether or single or multi-bit A/D conversion is employed. Depending upon the duration of a multipath component of a pulse such as multipath component 1500 a of FIG. 15 a is stored within the reference wave form data table, a block of reference data may be added with zeros at either or both ends. The use of a reference wave form data table provides important benefits to the receiver system, in particular allowing use of a lower quality receiver analog front end than would otherwise be acceptable as the above described process of self-calibration, storing referenced wave form data table 1100 , can compensate for distortion within the receiver as previously described. [0113] In operation the PSR sequence generator 1108 is responsive to the pseudo random sequence employed for transmitting the data to control the read timing from the reference wave form data table to compensate for the pseudo random (but deterministic) time modulation imposed on the variable, information—dependent phase and position modulation. Pattern controller 1300 also provides an end of pattern output signal 1308 for use in resetting the correlator as described further below. [0114] FIG. 4 shows details of the configuration of the multiply-accumulate units of correlator 514 . The correlator comprises a plurality, in one configuration 16 , of multiply units 1400 each coupled to a respective accumulator 1402 . Each multiplier unit 1400 receives the same block 1404 of sampled input data, as illustrated comprising 16 successively delayed samples (either one or multi-bit values). Each multiply unit 1400 also receives a block of reference signal samples 1406 , in one configuration comprising 16 successive samples of the reference signal wave form, from data table 1100 , but each of blocks 1406 is successively delayed so that the sampled input data is correlated in parallel by multiplier units 1400 with portions of the referenced signal wave form spanning a range (as illustrated, 16) of successive time slices of the referenced wave form. The effect of this is to slide the sampled input data block or time slice along the referenced wave form until a correlation is found but it is easier in practice to firstly change the referenced wave form delay rather than the sampled received data delay, and secondly to perform a plurality of correlation in parallel rather than employ a single slide window. [0115] Each of multiply units 1400 comprises a multiplier to multiply each input data sample with the corresponding reference data sample and provide an output to the corresponding accumulator 1402 so that the accumulator accumulates a correlation value from all (in this case 16) correlation operations in parallel. Each accumulator has an output 1408 coupled to a partial correlation store 1410 for writing an accumulated correlation value into the store. Each accumulator also has an input 1412 from a read output of store 1410 to allow a partial correlation value written into the store to be read back from the store and added to a further correlation value in each respective accumulator. Writing of data into the store and reading of data from the store is controlled by the phase control processor 1112 . The partial correlation store 1410 comprises a plurality of sets of memory locations, each set of memory locations storing a set of partial correlation values, one from each multiply-accumulate module (T1 . . . T16). Storage is provided for as many sets of partial correlation values as is needed to process a desired number of transmitted pulses as overlapping or interleaved multipath components. Thus, for example, two sets of memory locations for partial correlation values are provided for storing partial correlation values where multipath components of two successively transmitted pulses overlap or interleave. [0116] Data from each of the plurality of memory locations of a set of partial correlation results is provided on an output 1414 to discriminator module 612 . Discriminator 512 also provides a memory clear output 1416 for clearing or setting to zero a set of partial correlation values, and receives an end of pattern signal 1308 from pattern controller 1300 . Discriminator 612 provides an output 1418 to subsequent forward error correction modules such as a Viterbi decoder. Although reference has been made to store 1410 storing partial correlation, once the correlation of a complete set of multipath components of a received signal pulse is complete the accumulated correlation values from outputs 1418 are written into store 1410 thus providing a set of complete correlation values, that is taking account of all multipath components it has been decided to process, and these complete correlation values are available to the discriminator 612 via BUS 1414 . [0117] To illustrate the operation of the correlator 514 of FIG. 14 it is helpful to refer to FIG. 15 a . Broadly speaking the procedure is to correlate (accumulate) the first received multipath component 1500 a and to dump this into store 1410 , and then to correlate the next multipath component 1500 b , also accumulating the previously stored partial correlation for multipath component 1500 a by reading this from store 1410 adding this to the partial correlation value of multipath component 1500 b , and the total accumulated set of correlation values is then written back into store 1410 . This process is continued until a multipath component of a subsequent pulse is encountered, in this case multipath component 1502 a of pulse 1500 . The pattern controller 1300 of FIG. 13 then controls the reference wave form data table 1100 to provide a pulse shape appropriate for correlating with multipath component 1502 a and following the correlation operation the result of this correlation is dumped into a separate set of memory locations within store 1410 , this set of memory locations being allocated to the second pulse. The correlation operation for multipath components of the received signal continues with the partial correlation results being written into the set of memory locations for either the first or second pulse as appropriate, the pattern generator controlling the wave form data table to generate a reference wave shape for the appropriate multipath component. Thus continuing with the example of FIG. 15 a multipath component 1500 c of the first pulse is next accumulated with the partial correlation value read from store 1410 for the first pulse and dumped back into store 1410 . In this case this is the final processed multipath component pulse of 1500 though the accumulated correlation values in store 1410 for the first pulse can then be taken as complete correlation values and processed by discriminator 612 . The signal indicating that the complete set of multipath components has been correlated is provided by pattern controller 1300 since this controller is able to determine that the final stored multipath component has been processed. However correlation of pulse 1502 continues with multipath component 1502 b and when the first multipath component of a third pulse (is not shown in FIG. 1500 a ) received the set of partial correlation values which was previously used for pulse 1500 (and which was cleared by discriminator 612 after the complete correlation values for pulse 1500 were processed) is available for use for accumulating correlation values for this third pulse. [0118] FIG. 15 b shows, diagrammatically, the correlation of a multipath component 1510 a of a received UWB signal pulse 1510 with a set of referenced pulses 1512 a, b of which, for clarity, only two are shown. The referenced signal pulses are time shifted to either side of the received multipath component 1510 a and correlation with each of these referenced signal pulses provides a correlation value as schematically illustrated in graph 1514 . The shape of this curve, and the height and width of its peak may alter depending upon the received signal and referenced signal shape. In FIG. 15 b a set of (full) correlation values output from storage 1410 to discriminator 612 on BUS 1414 is diagrammatically illustrated by bar chart 1516 in which each bar 1518 represents an accumulated correlation value for one of the delayed versions of the referenced signal multipath component 1512 . It can be seen that most of the accumulated correlation values are close to a mean level 1520 but one of the accumulated values represented by bar 1522 is significantly different from the others. This represents the most likely pulse position; the bars 1524 , 1526 to either side of it represents next most probable pulse positions. Bar 1522 a is significantly greater than the average 1520 which applies a positive correlation (normal pulse) whilst bar 1522 b has a correlation value which is significantly less (more negative) than the average which implies a negative correlation that is an inverted received signal pulse as compared with the reference. Thus the correlator of FIG. 14 b is able to co-determine both the likely position (in time) of a received signal pulse and also the phase (normal or inverted) of the pulse and hence to co-determine information data modulated to both pulse position and pulse phase simultaneously. The use of both position and phase simultaneously to encode information data significantly enhances the information data carrying capacity of the system. [0119] In the above described system the correlator is employed for correlating successive multipath components of received signal pulses. However essentially the same arrangement can also be used for accumulating relation values for successively transmitting impulses carrying the same data. In other words a transmitter and/or receiver may employ redundancy, using two or more transmit pulses to carry substantially the same data, at the receiver processing these as though they were merely multipath components of a single pulse. This reduces the effective data rate (halving data rate where two pulses are received instead of one to transmit a given symbol) but potentially increases the range of a transmission system by providing greater energy per transmitted symbol. Such an arrangement may be employed adaptively, reducing the data rate but increasing reliability where transmission conditions are difficult or at the edge of range of a system. The reduction in effective data rate may be partially compensated for by increasing the pulse repetition frequency, providing that operation within the desired regulatory spectral envelope is maintained; the transmit power may also be adaptively controlled to facilitate this. [0120] No doubt alternatives will occur to the skilled person. It will be understood that the invention is not limited to the described embodiments and encompasses modifications apparent to those skilled in the art lying within the scope of the claims appended hereto. [0121] Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever. [0122] In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated. [0123] The entire disclosures of all applications, patents and publications, cited herein and of corresponding Great Britain application No. 0316897.8, filed Jul. 18, 2003, and U.S. Provisional Application Ser. No. 60/518,344, filed Nov. 10, 2003, are incorporated by reference herein. [0124] The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples. [0125] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.
This invention generally relates to wired and wireless ultra wideband (UWB) data communications apparatus and methods, and in particular to UWB receiver systems and architectures. An ultra wideband (UWB) receiver system comprising: a receiver front end to receive a UWB signal; an analogue-to-digital converter coupled to said receiver front end to digitise said received UBW signal; and a correlator coupled to said analogue-to-digital converter to correlate said digitised UWB signal with a reference signal.
Summarize the document in concise, focusing on the main idea's functionality and advantages.
[ "FIELD OF THE INVENTION [0001] This invention generally relates to wired and wireless ultra wideband (UWB) data communications apparatus and methods, and in particular to UWB receiver systems and architectures.", "The benefit of U.S. provisional 60/518,344 filed Nov. 10, 2003 is claimed.", "BACKGROUND TO THE INVENTION [0002] Techniques for UWB communication developed from radar and other military applications, and pioneering work was carried out by Dr G. F. Ross, as described in U.S. Pat. No. 3,728,632.", "Ultra-wideband communications systems employ very short pulses of electromagnetic radiation (impulses) with short rise and fall times, resulting in a spectrum with a very wide bandwidth.", "Some systems employ direct excitation of an antenna with such a pulse which then radiates with its characteristic impulse or step response (depending upon the excitation).", "Such systems are referred to as carrierless or “carrier free”", "since the resulting rf emission lacks any well-defined carrier frequency.", "However other UWB systems radiate one or a few cycles of a high frequency carrier and thus it is possible to define a meaningful centre frequency and/or phase despite the large signal bandwidth.", "The US Federal Communications Commission (FCC) defines UWB as a −10 dB bandwidth of at least 25% of a centre (or average) frequency or a bandwidth of at least 1.5 GHz;", "the US DARPA definition is similar but refers to a −20 dB bandwidth.", "Such formal definitions are useful and clearly differentiates UWB systems from conventional narrow and wideband systems but the techniques described in this specification are not limited to systems falling within this precise definition and may be employed with similar systems employing very short pulses of electromagnetic radiation.", "[0003] UWB communications systems have a number of advantages over conventional systems.", "Broadly speaking, the very large bandwidth facilitates very high data rate communications and since pulses of radiation are employed the average transmit power (and also power consumption) may be kept low even though the power in each pulse may be relatively large.", "Also, since the power in each pulse is spread over a large bandwidth the power per unit frequency may be very low indeed, allowing UWB systems to coexist with other spectrum users and, in military applications, providing a low probability of intercept.", "The short pulses also make UWB communications systems relatively unsusceptible to multipath effects since multiple reflections can in general be resolved.", "Finally UWB systems lend themselves to a substantially all digital implementation, with consequent cost savings and other advantages.", "[0004] FIG. 1 a shows an example of an analogue UWB transceiver 100 .", "This comprises an transmit/receive antenna 102 with a characteristic impulse response indicated by bandpass filter (BPF) 104 (although in some instances a bandpass filter may be explicitly included), couples to a transmit/receive switch 106 .", "[0005] The transmit chain comprises an impulse generator 108 modulatable by a baseband transmit data input 110 , and an antenna driver 112 .", "The driver may be omitted since only a small output voltage swing is generally required.", "One of a number of modulation techniques may be employed, typically either OOK (on-off keying i.e. transmitting or not transmitting a pulse), M-ary amplitude shift keying (pulse amplitude modulation), or PPM (pulse position modulation i.e. dithering the pulse position).", "Typically the transmitted pulse has a duration of <Ins and may have a bandwidth of the order of gigahertz.", "[0006] The receive chain typically comprises a low noise amplifier (LNA) and automatic gain control (AGC) stage 114 followed by a correlator or matched filter (MF) 116 , matched to the received pulse shape so that it outputs an impulse when presented with rf energy having the correct (matching) pulse shape.", "The output of MF 116 is generally digitised by an analogue-to-digital converter (ADC) 118 and then presented to a (digital or software-based) variable gain threshold circuit 120 , the output of which comprises the received data.", "The skilled person will understand that forward error correction (FEC) such as block error coding and other baseband processing may also be employed, but such techniques are well-known and conventional and hence these is omitted for clarity.", "[0007] FIG. 1 b shows one example of a carrier-based UWB transmitter 122 .", "A similar transmitter is described in more detail in U.S. Pat. No. 6,026,125.", "This form of transmitter allows the UWB transmission centre frequency and bandwidth to be controlled and, because it is carrier-based, allows the use of frequency and phase as well as amplitude and position modulation.", "Thus, for example, QAM (quadrature amplitude modulation) or M-ary PSK (phase shift keying) may be employed.", "[0008] Referring to FIG. 1 b , an oscillator 124 generates a high frequency carrier which is gated by a mixer 126 which, in effect, acts as a high speed switch.", "A second input to the mixer is provided by an impulse generator 128 , filtered by an (optional) bandpass filter 130 .", "The amplitude of the filtered impulse determines the time for which the mixer diodes are forward biased and hence the effective pulse width and bandwidth of the UWB signal at the output of the mixer.", "The bandwidth of the UWB signal is similarly also determined by the bandwidth of filter 130 .", "The centre frequency and instantaneous phase of the UWB signal is determined by oscillator 124 , and may be modulated by a data input 132 .", "An example of a transmitter with a centre frequency of 1.5 GHz and a bandwidth of 400 MHz is described in U.S. Pat. No. 6,026,125.", "Pulse to pulse coherency can be achieved by phase locking the impulse generator to the oscillator.", "[0009] The output of mixer 126 is processed by a bandpass filter 134 to reject out-of-band frequencies and undesirable mixer products, optionally attenuated by a digitally controlled rf attenuator 136 to allow additional amplitude modulation, and then passed to a wideband power amplifier 138 such as a MMIC (monolithic microwave integrated circuit), and transmit antenna 140 .", "The power amplifier may be gated on and off in synchrony with the impulses from generator 128 , as described in US'125, to reduce power consumption.", "[0010] FIG. 1 c shows a similar transmitter to that of FIG. 1 b , in which like elements have like reference numerals.", "The transmitter of FIG. 1 c is, broadly speaking, a special case of the transmitter of FIG. 1 b in which the oscillator frequency has been set to zero.", "The output of oscillator 124 of FIG. 1 b is effectively a dc level which serves to keep mixer 126 always on, so these elements are omitted (and the impulse generator or its output is modulated).", "[0011] FIG. 1 d shows an alternative carrier-based UWB transmitter 142 , also described in U.S. Pat. No. 6,026,125.", "Again like elements to those of FIG. 1 b are shown by like reference numerals.", "[0012] In the arrangement of FIG. 1 d a time gating circuit 144 gates the output of oscillator 124 under control of a timing signal 146 .", "The pulse width of this timing signal determines the instantaneous UWB signal bandwidth.", "Thus the transmitted signal UWB bandwidth may be adjusted by adjusting the width of this pulse.", "[0013] Ultra-wideband receivers suitable for use with the UWB transmitters of FIGS. 1 b to 1 d are described in U.S. Pat. No. 5,901,172.", "These receivers use tunnel diode-based detectors to enable single pulse detection at high speeds (several megabits per second) with reduced vulnerability to in-band interference.", "Broadly speaking a tunnel diode is switched between active and inactive modes, charge stored in the diode being discharged during its inactive mode.", "The tunnel diode acts, in effect, as a time-gated matched filter, and the correlation operation is synchronised to the incoming pulses.", "[0014] FIG. 1 e shows another example of a known UWB transmitter 148 , described in U.S. Pat. No. 6,304,623.", "In FIG. 1 e a pulser 150 generates an rf pulse for transmission by antenna 152 under control of a timing signal 154 provided by a precision timing generator 156 , itself controlled by a stable timebase 158 .", "A code generator 160 receives a reference clock from the timing generator and provides pseudo-random time offset commands to the timing generator for dithering the transmitter pulse positions.", "This has the effect of spreading and flattening the comb-like spectrum which would otherwise be produced by regular, narrow pulses (in some systems amplitude modulation may be employed for a similar effect).", "[0015] FIG. 1 f shows a corresponding receiver 162 , also described in US'623.", "This uses a similar timing generator 164 , timebase 166 and code generator 168 (generating the same pseudo-random sequence), but the timebase 166 is locked to the received signal by a tracking loop filter 170 .", "The timing signal output of timing generator 164 drives a template generator 172 which outputs a template signal and a correlator/sampler 176 and accumulator 178 samples and correlates the received signal with the template, integrating over an aperture time of the correlator to produce an output which is sampled at the end of an integration cycle by a detector 180 to determine whether a one or a zero has been received.", "[0016] FIG. 1 g shows a UWB transceiver 182 employing spread spectrum-type coding techniques.", "A transceiver of the general type is described in more detail in U.S. Pat. No. 6,400,754, to which reference may be made.", "[0017] In FIG. 1 g a receive antenna 184 and low noise amplifier 186 provide one input to a time-integrating correlator 188 .", "A second input to the correlator is provided by a code sequence generator 190 which generates a spread spectrum-type code such as a Kasami code, that is a code with a high auto-correlation coefficient from a family of codes with low cross-correlation coefficients.", "Correlator 188 multiplies the analogue input signal by the reference code and integrates over a code sequence period and may comprise a matched filter with a plurality of phases representing different time alignments of the input signal and reference code.", "The correlator output is digitised by analogue-to-digital converter 192 which provides an output to a bus 194 controlled by a processor 196 with memory 198 the code sequence generator 190 is driven by a crystal oscillator driven clock 200 a transmit antenna driver 202 receives data from bus 194 which is multiplied by a code sequence from generator 190 and transmitted from transmit antenna 204 .", "In operation coded sequences of impulse doublets are received and transmitted, in one arrangement each bit comprising a 1023-chip sequence of 10 ns chips, thus having a duration of 10 μs and providing 30 dB processing gain.", "Shorter spreading sequences and/or faster clocks may be employed for higher bit rates.", "[0018] The transceiver described in U.S. Pat. No. 6,400,754 uses a modification of a frequency-independent current-mode shielded loop antenna (described in U.S. Pat. No. 4,506,267) comprising a flat rectangular conducting plate.", "This antenna is referred to as a large-current radiator (LCR) antenna and when driven by a current it radiates outwards on the surface of the plate.", "[0019] FIG. 1 h shows a driver circuit 206 for such an LCR transmit antenna 208 .", "The antenna is driven by an H-bridge comprising four MOSFETs 210 controlled by left (L) and right (R) control lines 212 , 214 .", "By toggling line 214 high then low whilst maintaining line 214 low an impulse doublet (that is a pair of impulses of opposite polarity) of a first polarity is transmitted, and by toggling line 212 high then low whilst holding line 214 low an impulse doublet of opposite polarity is radiated.", "The antenna only radiates whilst the current through it changes, and transmits a single gaussian impulse on each transition.", "[0020] FIGS. 2 a to 2 h show some examples of UWB waveforms, FIG. 2 a shows a typical output waveform of a UWB impulse transmitter, and FIG. 1 b shows the power spectrum of the waveform of FIG. 2 a .", "FIG. 2 c shows a wavelet pulse (which when shortened becomes a monocycle) such as might be radiated from one of the transmitters of FIGS. 1 b to 1 d .", "FIG. 2 d shows the power spectrum of FIG. 2 c .", "FIG. 2 e shows an impulse doublet and FIG. 2 f the power spectrum of the doublet of FIG. 2 e .", "It can be seen that the spectrum of FIG. 2 f comprises a comb with a spacing (in frequency) determined by the spacing (in time) of the impulses of the doublet and an overall bandwidth determined by the width of each impulse.", "It can also be appreciated from FIGS. 2 e and 2 f that dithering the pulse positions will tend to reduce the nulls of the comb spectrum.", "FIG. 2 g shows examples of basis impulse doublet waveforms for a logic 0 and a logic 1 FIG. 2 h shows an example of a TDMA UWB transmission such as might be radiated from the transceiver of FIG. 1 g , in which bursts of Code Division Multiple access (CDMA)-encoded data are separated by periods of non-transmission to allow access by other devices.", "[0021] Ultra wideband communications potentially offer significant advantages for wireless home networking, particularly broadband networking for audio and video entertainment devices, because of the very high data rates which are possible with UWB systems.", "However, UWB communications also present a number of special problems, most particularly the very low transmit power output imposed by the relevant regulatory authorities, in the US the FCC.", "Thus the maximum permitted power output is presently below the acceptable noise floor for unintentional emitters so that a UWB signal effectively appears merely as noise to a conventional receiver.", "This low power output limits the effective range of UWB communications and there is therefore a need to address this difficulty.", "[0022] One way to improve the range of a UWB communications link is to adopt a rake receiver type approach to combine the energy in a plurality of multipath components of a received signal.", "Multipath effects arise when a signal from a transmitter to a receiver takes two or more different paths (multipaths) such as a direct path between a transmit and receive antenna and an indirect path via reflection off a surface.", "In a multipath environment two or more versions of a transmitted signal arrive at the receiver at different times.", "Most wireless environments, and in particular indoor environments, have significant levels of multipath which, in a conventional RF communications system, typically produces a comb-like frequency response, the multiple delays of the multipath components of the received signal giving the appearance of tines of a rake.", "The number and position of multipath channels generally changes over time, particularly when one or both of the transmitter and receiver is moving.", "[0023] It is helpful to briefly review the operation of a conventional rake receiver before going on to consider a known UWB rake-type receiver.", "[0024] In a spread spectrum communication system a baseband signal is spread by mixing it with a pseudorandom spreading sequence of a much higher bit rate (referred to as the chip rate) before modulating the rf carrier.", "At the receiver the baseband signal is recovered by feeding the received signal and the pseudorandom spreading sequence into a correlator and allowing one to slip past the other until a lock is obtained.", "Once code lock has been obtained, it is maintained by means of a code tracking loop such as an early-late tracking loop which detects when the input signal is early or late with respect to the spreading sequence and compensates for the change.", "Alternatively a matched filter may be employed for despreading and synchronisation.", "[0025] Such a system is described as code division multiplexed as the baseband signal can only be recovered if the initial pseudorandom spreading sequence is known.", "A spread spectrum communication system allows many transmitters with different spreading sequences all to use the same part of the rf spectrum, a receiver “tuning”", "to the desired signal by selecting the appropriate spreading sequence (CDMA—code division multiple access).", "[0026] One advantage of conventional spread spectrum systems is that they are relatively insensitive to multipath fading.", "A correlator in a spread spectrum receiver will tend to lock onto one of the multipath components, normally the direct signal which is the strongest.", "However a plurality of correlator may be provided to allow the spread spectrum receiver to lock onto a corresponding plurality of separate multipath components of the received signal.", "Such a spread spectrum receiver is known as a rake receiver and the elements of the receiver comprising the correlator are often referred to as “fingers”", "of the rake receiver.", "The separate outputs from each finger of the rake receiver are combined to provide an improved signal to noise ratio (or bit error rate) generally either by weighting each output equally or by estimating weights which maximise the signal to noise ratio of the combined output (“Maximal Ratio Combining”—MRC).", "[0027] FIG. 3 a shows the main components of a typical rake receiver 300 , A bank of correlators 302 comprises, in this example, three correlators 302 , 302 and 302 each of which receives a CDMA spread spectrum signal from input 304 .", "The correlators are known as the fingers of the rake;", "in the illustrated example the rake has three fingers.", "The CDMA signal may be at baseband or at IF (Intermediate Frequency).", "Each correlator locks to a separate multipath component which is delayed by at least one chip with respect to the other multipath components.", "More or fewer correlators can be provided according to a quality-cost/complexity trade off.", "The despread output from a correlator is a signal with a magnitude and phase modified by the attenuation and phase shift of the multipath channel through which the multipath component locked onto by the finger of the rake receiver has been transmitted.", "A channel estimate comprising a complex number characterising the phase and attenuation of the communications channel, in particular for the multipath component of the channel the rake finger has despread, may be obtained, for example using a training sequence.", "The channel estimate may then be conjugated to invert the phase (and optionally normalised) and used to multiply the received signal to compensate for the channel.", "[0028] The outputs of all the correlators go to a combiner 306 such as an MRC combiner, which adds the outputs in a weighted sum, generally giving greater weight to the stronger signals.", "The weighting may be determined based upon signal strength before or after correlation, according to conventional algorithms.", "The combined signal is then fed to a discriminator 308 which makes a decision as to whether a bit is a 1 or a 0 and provides a baseband output.", "The discriminator may include additional filtering, integration or other processing.", "The rake receiver may be implemented in either hardware or software or a mixture of both.", "[0029] The effects of multipath propagation on UWB transmissions are not the same as on conventional RF transmissions.", "In particular where a UWB signal comprises a succession of wavelets or pulses (the terms are used substantially synonymously in the specification), because of the short duration and relatively long separation (in time) of these pulses it is often possible to substantially time-resolve the pulses belonging to multipath components of the UWB signal.", "In simple terms, the delays between the arrival of pulses in different multipath components originating from a single transmitted UWB pulse are often long enough to make it unlikely that two pulses arrive at the same time.", "This is described further below and can be exploited to advantage in a UWB receiver design.", "[0030] It is known to apply conventional rake receiver techniques to UWB communications systems, as described for example in WO01/93441, WO01/93442, and WO01/93482.", "FIG. 3 b , which is taken from WO01/93482, shows such a transceiver;", "similar arrangements are described in the other two specifications.", "[0031] Referring to FIG. 3 b , this shows a UWB transmitter 7 0 , 21 , 17 , 23 , 25 , 27 , 1 and a UWB receiver 1 , 27 , 3 , 29 , 31 , 1-N , 7 1-N , 9 .", "The receiver comprises a plurality of tracking correlators 31 1 - 31 N together with a plurality of timing generators 7 1 - 7 N , and as described in WO'482 (page 15) during a receive mode of operation the multiple arms can resolve and lock onto different multipath components of a signal.", "By coherent addition of the energy from these different multipath signal components the received signal to noise ratio may be improved.", "However the design of '482 is relatively physically large, expensive and power hungry to implement and fails to take advantage of some aspects of UWB multipath transmission.", "SUMMARY OF THE INVENTION [0032] In one aspect the invention provides an ultra wideband (UWB) receiver system comprising a receiver front end to receive a UWB signal;", "an analogue-to-digital converter coupled to said receiver front end to digitise said received UWB signal;", "and a correlator coupled to said analogue-to-digital converter to correlate said digitised UWB signal with a reference signal.", "[0033] Digitising the received UWB signal prior to correlation with a reference signal helps to reduce the cost, size, and power consumption of the receiver by facilitating further processing in accordance with a number of digital techniques as described below.", "For example one digital correlator correlating a pair of signals (the received and reference signals) may be employed to correlate a received pulse having a plurality of multipath components, rather than a separate correlation being needed for each separate multipath component.", "Correlation speed may also be increased by correlating a set of digitised samples of an incoming UWB signal with a reference signal.", "More generally digitising prior to the correlator facilitates time multiplexing of a correlator, for example storing partial or intermediate correlation results, and thus facilitates the provision of a much larger number of correlators than might otherwise be possible, thus helping to provide an improved signal to noise ratio.", "Multiple correlators may be employed in parallel, for example for pipelined correlation operations, and by multiplexing correlators in the time domain, sharing a single correlator between different multipath components of the same pulse and/or between different pulses a plurality of logically parallel correlators may be provided by a single physical correlator.", "In a preferred embodiment the UWB signal is a carrierless signal comprising a plurality of pulses or wavelets, thus facilitating such time multiplexing since much of the reference wave form is then substantially zero, comprising short pulses separated by longer periods of substantially zero signal, providing spaces in which a correlator or multiple-accumulator may be multiplexed for use in correlating other (later or earlier) transmitted pulses.", "Thus the correlator can be faster, more efficient, smaller and potentially cheaper.", "[0034] As UWB signals by their nature have a very wide bandwidth, for example 500 MHz or greater even when the UWB spectrum is subdivided into bands, the analogue-to-digital converter preferably operates at 10 9 samples per second and may operate at 10 10 samples per second or more.", "Since such fast analogue-to-digital conversion can have a high power consumption the reference signal, for example from a reference signal generator, may be used to control a power supply to the converter so that the power consumption of the converter can be reduced in periods where there is no expected received signal (pulse).", "Thus the converter may be inhibited or its power effectively removed during periods when no multipath component of a pulse is expected.", "Thus in another aspect the invention provides a method of controlling an analogue-to-digital converter in accordance with these techniques.", "[0035] As the received UWB signal may be at a very low level or even in the noise (because there may be redundancy in the transmitted data, for example by distributing a data bit over a plurality of successively transmitted pulses) an analogue-to-digital converter with a multiple bit resolution is indicated.", "However the number of bits required may be reduced by employing a controllable gain device such as a switched or programmeable attenuator prior to the analogue-to-digital converter and controlling this using the reference signal.", "Thus when a low level multipath component is expected the gain may be increased or attenuation reduced.", "In some circumstances a one bit analogue-to-digital converter may even be employed, which simplifies later correlation since a one-bit multiply may be implemented by means of an EXOR gate.", "Optionally one or more statistical characteristics of the received UWB signal may be monitored in order to adjust the signal prior to digitisation.", "[0036] Where the UWB signal comprises a plurality of pulses a plurality of correlation or multiply-accumulate modules may be employed to perform a plurality of correlations substantially in parallel between the digitised UWB signal and differently delayed versions of the reference signal to locate a pulse.", "As described further below in embodiments it is highly advantageous to delay the reference signal rather than the digitised sample data as using a look-up table in memory it is relatively straightforward to generate differently delayed versions of a stored signal.", "In embodiments this provides much faster signal acquisition and tracking than a conventional sliding window or early-late approach thus facilitating managing the very fast stream of data from the analogue-to-digital converter.", "The skilled person will appreciate that the bandwidth of the digital ‘pipe’ from this converter is roughly three orders of magnitude wider than the level at which conventional digital RF processing generally takes place (10 GHz as compared with 10 MHz).", "[0037] In preferred embodiments each of the correlation modules correlates a plurality of multipath components of a transmitted pulse and where these interleave but do not substantially overlap a correlation module may be time multiplexed to correlate multipath components of successively transmitted pulses with the reference signal.", "This further facilitates rapid processing of the digitised incoming UWB signal.", "Where correlation is performed against a plurality of multipath components a single template may be used for all multipath components but preferably a separate template is used for at least some of or each of the multipath components for improved correlation with the received signal.", "The reference signal template for one or more multipath components may be derived by training the receiver.", "For example an associated UWB transmitter may be employed to directly transmit a signal to the receiver to calibrate out or at least compensate for phase and/or gain distortions or non-linearities introduced by the receiver (analogue) front end and/or analogue-to-digital converter.", "This is important in a UWB system since the ultra wideband input stage will generally have phase and gain characteristics which vary significantly over the receiver bandwidth thus introducing significant distortions to the transmitted pulse shape.", "The associated transmitter may provide a timing signal directly to the receiver, for example across a direct wired connection, so that the receiver knows when to store received data into a reference signal memory in order to construct a receive signal template.", "A second training stage may optionally (but preferably) also be applied in which a signal from a remote transmitter is acquired using the stored reference signal and then used to store a second reference signal which takes account of the distortions introduced by the channel for each multipath component.", "[0038] It will be appreciated that the above described correlator may be employed to locate the position of a pulse in time (pulse-position modulation).", "However in preferred embodiments the correlator includes a discriminator which may be employed to determine the phase of a received pulse, for example determining whether the pulse is upright or inverted (bi-phase modulation).", "This bi-phase determination effectively comes at no extra cost to the pulse position determination and is effectively co-determined with the pulse position.", "This permits a doubling in the number of data bits to be sent as compared with either pulse position modulation or bi-phase modulation when used separately.", "Although it is known to dither the position of bi-phase pulses, for example using a pseudorandom sequence, it has not previously been recognised that a pulsed UWB signal may be modulated with information data to be communicated across a UWB link using pulse position modulation (PPM) in which a pulse position is dependant upon the information data and at the same time bi-phase modulation (or M-ary phase modulation) in which the pulse phase is also dependant upon the information data, two or more information bits being encoded as a combination of pulse phase and pulse position.", "[0039] Preferably the analogue-to-digital converter comprises a plurality of A-to-D conversion modules to provide a plurality of successively delayed samples of the UWB signal substantially in parallel, for example using a phase-tapped clock.", "The correlator may then be configured to process these successively delayed samples substantially simultaneously to allow a time-slice of the received signal to be correlated with a time-slice of the reference signal, preferably the time-slice having sufficient duration to encompass a substantial portion of a pulse within the UWB signal.", "Since a single transmitted pulse is generally received as a set of multipath components each comprising a version of the pulse the time-slice preferably extends over the duration of a pulse of a multipath component rather than over the entire set of multipath components which may be significantly delayed with respect to one another.", "A correlator to correlate time-slices of the received and reference signals each comprising a plurality of samples may comprise a plurality of multipliers in parallel coupled to a common accumulator.", "[0040] The reference signal is preferably provided from a reference signal memory, and advantageously within this memory the reference signal may be stored as a set of pulse shapes each separated by a delay, each pulse shape representing an expected pulse shape of a received multipath component of a transmitted pulse.", "Thus in a preferred embodiment the reference signal memory stores sets of data samples defining pulse shapes and associated data values defining delays between these pulses, that is between the reception of different multipath components of a pulse.", "[0041] Preferably the reference signal memory is configured to provide a plurality of stored reference signal values for different, successively delayed versions of the reference signal substantially simultaneously.", "This facilitates rapid location of the exact position in time of a multipath component of a pulse since the successively delayed versions of the pulse may be correlated with the incoming received signal in parallel.", "Thus the reference signal memory preferably has a plurality of outputs so that when the memory is addressed each of these outputs can provide a data sample corresponding to a different point on the stored reference signal waveform.", "In fact, as described above, it is preferable for the reference signal memory to have a plurality of sets of outputs each set of outputs providing a time-slice of samples of the stored reference signal extending over a period approximately equal to or greater than the duration of a multipath component of a pulse, the sets of samples being successively delayed to provide, in effect, successively delayed pulse shapes.", "It is further preferable that the delay of each set of samples, that is of each pulse shape, should correspond to an integral number (such as one) sample periods so that these successively delayed sets of samples may be provided by appropriate wiring of outputs from the memory.", "For example first and second sets of 16 samples delayed by one sample will have 15 sample values in common and need only 17 outputs from the memory to provide 32 sets of samples defining two pulse shapes delayed by one sample with respect to one another.", "[0042] Preferably the receiver system also includes a controller for identifying data in a received UWB signal which can be written into the reference signal memory for use as a template in later correlations.", "This facilitates training of the receiver to perform correlations with unexpected received UWB signal rather than an ideal UWB signal.", "It will be appreciated that the controller need not itself read the digitised signal to be used as a template but need only identify which portion of an incoming signal may be employed for this purpose, for example using the correlator.", "In some embodiments more than one reference signal may be stored.", "For example a reference signal may be stored for each of a plurality of transmitters from which the receiver system receives signals, allowing a different reference signal to be employed for each transmitter, and therefore allowing the receiver to compensate for the potentially different multipath channel to each transmitter.", "The reference signal for a transmitter may then be selected according to which transmitter the receiver is communicating with (or in some embodiments correlations with more than one reference signal may be performed effectively in parallel, for example by multiplexing).", "[0043] In a related aspect the invention provides an ultra wideband (UWB) receiver system for reception of UWB signals from a plurality of UWB transmitters, the receiver system comprising: a receiver front end to receive a said UWB signal;", "a correlator coupled to said receiver front end to correlate said UWB signal with a reference signal;", "and means to select one of a plurality of said reference signals for receiving a signal from a corresponding one of said transmitters.", "[0044] The above described features and aspects of the invention may advantageously be combined and permuted, as will be understood by the skilled person.", "BRIEF DESCRIPTION OF THE DRAWINGS [0045] These and other aspects of the present invention will now be further described, by way of example only, with reference to the accompanying figures in which: [0046] FIGS. 1 a to 1 h show, respectively, a typical UWB transceiver, a first example of a carrier-based UWB transmitter, a variant of this first example transmitter, a second example of a carrier-based UWB transmitter, a third example of a UWB transmitter, a receiver for the third example transmitter, a UWB transceiver employing spread spectrum techniques, and a driver circuit for a large-current radiator antenna;", "[0047] FIGS. 2 a to 2 h show examples of UWB waveforms;", "[0048] FIGS. 3 a and 3 b show, respectively, the main elements of a conventional rake receiver for spread-spectrum signals, and a block diagram of a known UWB transceiver employing conventional rake receiver techniques;", "[0049] FIGS. 4 a to 4 d show, respectively, a transmitted UWB signal comprising a single pulse, an example of a received version of the transmitted pulse of FIG. 4 a with multipath reflections and other propagation effects, a series of transmitted UWB pulses of the type shown in FIG. 4 a , and a received signal corresponding to the transmitted signal of FIG. 4 c showing overlapping multipath reflections;", "[0050] FIG. 5 shows an overview block diagram of a UWB receiver embodying aspects of the present invention, [0051] FIG. 6 shows a simplified block diagram of a demodulator architecture for use with the receiver of FIG. 5 ;", "[0052] FIG. 7 shows a timing diagram illustrating timing variations of multipath components of a pulse with respect to pulse repetition frequency;", "[0053] FIG. 8 shows diagrammatically a modulation scheme for use with the D modulator of FIG. 6 , [0054] FIGS. 9 a and 9 b show, respectively, a data frame format and pilot tone pulses for the receiver of FIG. 5 ;", "[0055] FIGS. 10 a and 10 b show, respectively, a UWB transmitter and a pulse generator for the UWB transmitter;", "[0056] FIGS. 11 a and 11 b show, respectively, a signal acquisition and tracking system for the receiver of FIG. 5 , and a waveform memory data format;", "[0057] FIGS. 12 a and 12 b show, respectively, a flow diagram of a signal acquisition procedure, and a diagrammatic illustration of a signal hunt process;", "[0058] FIGS. 13 a and 13 b show, respectively, a reference waveform generation system, and a variant of the system of FIG. 13 a;", "[0059] FIG. 14 shows a block diagram of a correlator for the demodulator of FIG. 6 ;", "[0060] FIGS. 15 a and 15 b show, respectively, received signals with interleaved multipath components, and a diagrammatic illustration of the operation of the correlator of FIG. 14 .", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0061] As previously mentioned a transmission medium coupling a UWB transmitter and UWB receiver will typically give rise to a number of physical effects that complicate the function of the receiver.", "The transmission medium may comprise a wireless or wired transmission channel.", "The physical effects include multiple path reflections, which result in multiple pulses at the receiver or each transmitted pulse, in some cases these pulses being phase inverted.", "Dispersion, frequency dependent continuation and other properties of the transmission medium distort the pulse shape.", "Interference and noise sources are received in addition to the desired pulse data.", "Noise sources include thermal noise (from the receiver itself), narrow band interference from radio transmitters sharing the same frequency spectrum, and broadband interference (from switching and alike).", "There may also be interference from co-located UWB systems sharing the same physical space for electrical cabling.", "A UWB receiver should preferably be capable of dealing with all these effects.", "[0062] Referring now to FIG. 4 , FIG. 4 a shows an example of a transmitted UWB pulse, which in this example has a duration of approximately 100 ps.", "FIG. 4 b shows the same pulse as it might be seen by a UWB receiver.", "As can be seen the received pulse has a plurality of multipath components and also exhibits distortion and other propagation effects.", "Multipath components are received over a time scale which depends upon the transmission channel but which may, for example, be between 10 ns and 100 ns (the pulses shown in this diagram are not to scale), multipath at the longer end of this range being observed in wired systems such as UWB over mains (AC power cable) transmissions as described in the co-depending UK Patent Application No. 0222828.6 filed on 2 nd Oct. 2002.", "The first received multipath component need not be the largest (as shown in FIG. 4 b ) and may be significantly distorted or even inverted.", "[0063] FIG. 4 c illustrates a series of transmitted pulses and FIG. 4 d an example of a corresponding received signal.", "It can be seen that multipath reflections from one pulse may overlap with the first signals from the next pulse.", "This problem is exasperated when timing modulation is applied to a transmitted pulse.", "[0064] FIG. 5 shows a block diagram of a UWB receiver 500 embodying an aspect of the present invention.", "[0065] An incoming UWB signal is received by an antenna 502 , which may comprise a capacitive an/or inductive coupling to a cable system such as a mains power cable or a telephone cable.", "The received UWB signal is provided to an analog front end block 504 which comprises a low noise amplifier (LNA) and filter 506 and an analog-to-digital converter 508 .", "A set of counters or registers 510 is also provided to capture and record statistics relating to the received UWB input signal.", "The analog front end 504 is primarily responsible for converting the received UWB signal into digital form.", "[0066] The digitised UWB signal output from front end 504 is provided to a demodulation block 512 comprising a correlator bank 514 and a detector 516 .", "The digitised input signal is correlated with a reference signal from a reference signal memory 518 which discriminates against noise and the output of the correlator is then fed to the defector which determines the n (where n is a positive integer) most probable locations and phase values for a received pulse.", "[0067] The output of the demodulation block 512 is provided to a conventional forward error correction (FEC) block 520 .", "In one implementation of the receiver FEC block 520 comprises a trellis or Viterbi state decoder 522 followed by a (de) interlever 524 , a Reed Solomon decoder 526 and (de) scrambler 528 .", "In other implementations other codings/decoding schemes such as turbo coding may be employed.", "[0068] The output of FEC block is then passed to a data sychronisation unit 530 comprising a cyclic redundancy check (CRC) block 532 and de-framer 534 .", "The data sychronisation unit 530 locks onto and tracks framing within the received data separating MAC (Media Access Control) control information from the application data stream(s) providing a data output to a subsequent MAC block (not shown).", "[0069] A control processor 536 comprising a CPU (Central Processing Unit) with program code and data storage memory is used to control the receiver.", "The primary task of the control processor 536 is to maintain the reference signal that is fed to the correlator to track changes in the received signal due to environmental changes (such as the initial determination of the reference wave form, control over gain in the LNA block 506 , and on-going adjustments in the reference wave form to compensate for external changes in the environment).", "[0070] Referring now to the analog front end 504 in more detail, in a preferred arrangement the LNA block 506 amplifies the signal received from the antenna or cable coupling.", "The amplifier design contains a fixed frequency passive filter that rejects signals out side of the FCC/ETSC permitted spectral band (3.1-10.6 GHz), as well as rejecting signals from the 5 GHz UNII frequency band.", "Rejection of such signal areas prevents strong narrow band transmissions from saturating the subsequent A/D converter.", "It is particularly important to reject signals that are likely to be co-located with a UWB device, such as 802.11, Bluetooth and mobile phone frequencies.", "[0071] The LNA also contains a switchable attenuator that may be used to adjust the signal level fed to the A/D unit.", "The attenuator may be controlled directly by both the control processor 536 and the reference signal.", "The purpose of the attenuator is to avoid input saturation at the A/D unit, while maintaining sufficient sensitivity to detect the received pulse waveform.", "[0072] The reference waveform from the Detector unit may also control the attenuation in real time, allowing different gain settings to be applied to different portions of the multipath signals that are received from a single pulse.", "The A/D converter 508 may take a variety of forms.", "In a preferred embodiment the A/D converter 508 is logically configured as a continuous sampler, effectively providing a continuous stream of samples at a suitable rate as determined by the upper frequency of the relevant UWB band and the Nyqust criterion, for example 20G samples per seconds (20 GHz) for a 10 GHz upper frequency.", "Physically, however, the A/D module may comprise a bank of samplers, for example 16 to provide 16 samples for each received pulse, successively triggered by a phase tapped clock to provide a snapshot of a portion of a received UWB signals at different phases which may then be used to provide an input to the correlator banks 514 of demodulation block 512 .", "In this way parallel blocks of signal samples may be provided at a rate of a few hundred megahertz, for example at substantially the pulse repetition frequency (PRF) rate thus effectively reducing the primary digitisation clocks speed to this rate;", "preferably each block substantially spans the duration of a received UWB pulse.", "Implementing the sampler as a plurality of parallel sampling circuits operating of a phase tapped reference clock facilitates the fabrication of suitable sample (and hold) devices on conventional silicon processors.", "[0073] Some examples of fast A/D converters are the described in the following documents, which are hereby incorporated by referenced: “A 20GSamples/s 8-Bit A/D Convertor with a 1 MB memory in 0.18 μCMOS presented by Brian Setterberg of Agilent Technologies, Inc., at the 2003 IEEE International Solid-State Circuit Conference (ISSCC)”;", "“A Serial-Link Transceiver Based on 8 -Gsamples/s A/D and D/A Converters in 0.25 μm CMOS presented by Chih-Kong Ken Yang, Vladimir Stojanovic, Siamak Modjtahedi, Mark A, Horowitz and William F. Ellersick, IEEE Journal of Solid-State Circuits, Vol 36, No 11 , Nov. 2001”;", "published US Patent Applications 2002 0167373 and 2002 0145484.", "[0074] Depending upon the application the A/D converter may either be a single-bit converter or a multi-bit converter, and may either monitor the received voltage level or the power level in the received signal.", "The A/D converter 508 may comprise a non-continuous sampler where the sampler is run only around the expected time of arrival of a received pulse (or around a desired time slice when hunting for a received pulse) and is substantially inactive at other times.", "In this way a high sampling rate may effectively be achieved but with advantages such as reduced power consumption.", "[0075] In general, it is desirable to gain as much information about the input signal as possible, favouring a multi-bit voltage sensitive sampling scheme.", "However, implementation constraints (physical silicon area and power consumption) mean that such a scheme is preferably only used for devices where immunity to noise (including unexpected narrow band interference) is important, for example where operation in close proximity to an 802.11 system is envisaged.", "In some arrangements sure bit conversion permits an acceptable compromise.", "[0076] Non-continuous sampling can offset some of the disadvantages of such a sampler, but can constrain the range of possible delay modulation values that can be detected, thereby reducing the potential information that can be carried by each pulse.", "Such a trade-off is often acceptable in systems where there are many co-located independent pulse transmissions, since the risk of ‘collisions’ between pulses from different transmissions is reduced.", "[0077] Single bit sampling is prone to saturation but offers a significant saving in silicon cost and power consumption and is therefore preferable level based A/D converters benefit from accurate control the input signal gain.", "The AFE 504 therefore preferably contains counters that monitor statistics of the input signal conversion, recording the number of values recorded in each of the sampling levels over some period of time.", "Software running on the Control Processor periodically reads these values and resets the counters.", "The software may then use these to determine an optimium setting for the gain/attenuation control applied to the received signal by LNA unit 506 .", "For such purposes, the software may assume that the received signal is, on average, a gaussian noise signal.", "[0078] Referring now to the demodulator block 512 , this is responsible for extracting a data signal imposed on the pulses by a transmitter.", "[0079] The scheme described here is specifically designed to decode modulation by means of the pulse arrival time or by the pulse phase.", "It may also be adapted to detect modulation by means of the pulse shape (spectral modulation).", "[0080] The input to the demodulator is a stream of sample data from the AFE 504 ;", "the output is a stream of decoded data bits.", "The output data rate is substantially constant fixed by the PRF (Pulse Repetition Frequency) and the number of bits encoded by each pulse.", "The operating parameters of the demodulator (PRF and bit-encoding) are typically fixed for a given transmitter.", "However, the demodulator (and other system parameters, such as AFE gain) may be time multiplexed by the MAC processor in order to facilitate near simultaneous reception from multiple transmitters.", "[0081] The demodulator contains units to correlate the received signal against a reference signal (programmed and maintained to track changes in the external signal propagation environment) by control processor 536 .", "The detailed form of the demodulator is shown in FIG. 6 .", "[0082] Referring to FIG. 6 , this shows a simplified block diagram of demodulator 512 of FIG. 5 ;", "like elements to those of FIG. 5 are indicated by like reference numerals.", "The input from the wireless antenna or wired interface and amplifier/filter unit 506 is implemented in discrete analog circuitry, and the A/D (sampler) 508 and demodulator 512 are implemented in the sampling clock domain which has, in one embodiment, an effective range of 25 GHz, corresponding to an actual clock rate of 250 MHz.", "The system control logic and output to the forward error correction apparatus also operates at 250 MHz.", "[0083] The correlator 514 comprises a bank of multiply-accumulate units 600 each of which receives an input signal sample (comprising a set of samples of the input signal at successive sampling intervals) and multiplies this by a reference sample (comprising a set of samples of a reference waveform at successive sampling intervals) provided by reference waveform synthesiser 518 .", "In the case of single bit A/D sampling the multiplier operation may be implemented using a simple XOR gate.", "The accumulators average the (correlation) data over a number of pulses, by averaging over (successive) transmitted pulses bearing the same encoded data and/or averaging over multipath components.", "[0084] The reference signal generator or synthesiser 518 provides the reference signal to the multiply-accumulate units 600 under control of a pattern sequencer 602 .", "The pattern sequencer is controlled by a PSR (Pseudo Random) sequence lock acquisition module 604 , preferably implemented in software as described later.", "Conceptually the pattern sequencer 602 provides a reference waveform 606 to a plurality of delay units 608 to provide a plurality of successively delayed versions of the reference waveform to multiply-accumulate units 600 .", "However although illustrated as a pipeline system with multiply-accumulated delay taps equivalent to a sample period to reduce the effective clock speed the reference waveform is preferably applied in parallel to the multiply-accumulate units 600 as described later.", "Such a parallel implementation is possible because the reference waveform is stored in memory and therefore a parallel set of differently delayed reference waveforms may be read out from the memory substantially simultaneously;", "implementation of the demodulator would be significantly more complex were delay taps conceptually applied to the incoming received UWB signal sample data since without additional complexity this would not be readily available in the form of successively delayed time windows of samples of parallel in samples.", "[0085] The reference signal for the correlator is programmed into the reference signal generator 518 by software running on control processor 536 , which preferably uses a training algorithm to determine the receiver response (that is, amptitude and phase distortion to a transmitted pulse).", "The control processor 536 also maintains a clock phase locked to the PRF (Pulse Repetition Frequency) of the transmitter from which signals are being received by using the arrival times of detected pulses relative to an internal timing reference (Local Crystal Oscillator).", "A power control output 610 from the reference waveform generator may also be employed to gate power to the A/D and sampling circuitry 508 to put this circuitry into a reduced power mode in periods where there is no expected received signal.", "This is particularly advantageous in systems using a multi-bit A/D since these often have a relatively large power consumption.", "[0086] A multiply-accumulate unit 600 provide outputs to a discriminator 612 which determines the sign and peak value (or values if probabilistic outputs are supplied to the following stage of the (absolute) value maximum accumulator output).", "The discriminator outputs provide an output data signal identifying the position of a received pulse and the pulse phase (that is, normal or inverted).", "A constellation decoder maps this position/phase data from the discriminator to an n-bit symbol which is then passed to the forward error correction block 520 .", "[0087] The demodulator 512 has a plurality of interfaces to other parts of the receiver system, each of which is preferably via a data synchroniser 616 a, b, c , such as a register or buffer.", "Thus the multiply-accumulate units 600 provide an output to the control processor 536 for calibration of the receiver front end (and preferably also the transmission channel) and for location processing to facilitate physical location of a UWB receiver according to known techniques.", "The interface between the constellation decoder 614 and FEC blocks 520 is preferably also implemented via a buffer.", "The PSR lock acquisition module 502 preferably has a bi-directional interface to a software control function implemented on control processor 536 to provide functions such as physical location of the receiver, delay tracking, and data (de) whitening.", "[0088] Referring next to FIG. 7 this shows relative timings of transmitted data pulses and multipath components of such pulses as seen by the receiver.", "As can be seen from FIG. 7 a typical delay span for a multipath reflection is between 1 and 100 ns whereas a typical interval between successive transmitted data pulses is between 2 and 10 ns.", "It can therefore be appreciated that a multipath reflection of a one pulse may arrive following a direct, line of sight transmission of the next pulse, or even of the next few pulses.", "The multipath reflections may also be phase inverted subject to different path distortions from the direct path.", "[0089] In a simple but less preferred arrangement the multiply-accumulate stages 600 of the correlator only integrate multipath energy over the inter-transmit pulse period so that, for example in FIG. 7 , multipath components arriving outside the 2-10 ns delay range would be ignored.", "However in general typical multipath delays are greater than the average inter-transmit pulse period, and thus significant energy may be lost with this approach.", "The problem is exacerbated if pseudo-random timing jitter is applied to the timing of the transmitted pulses to achieve spectral whitening.", "[0090] For these reasons it is therefore preferable to implement two or more correlator banks, that is banks of multiply-accumulate units 600 as shown in FIG. 6 , parallel to facilitate pipelining of the pulse integrations.", "Such parallelism implemented by repetition of the correlator logic but in a preferred arrangement this parallelism is achieved by multiplexing the use of a single set of multiply-accumulate chains 600 , for example by keeping track of distinct sets of accumulator values in a static RAM (Random Access Memory) buffer memory.", "[0091] FIG. 8 shows a schematic diagram of a UWB signal employing a preferred modulation scheme for the above described receiver and which may be generated by a transmitter described later with reference to FIG. 10 .", "The signal of FIG. 8 may be employed in a wireless or wired UWB transmission system.", "[0092] The signal 800 comprises a plurality of wavelets or pulses 802 each of which has either a normal or inverted form to encode a single bit of information data to be transmitted;", "FIG. 8 shows two normal (rather than inverted) examples of such pulses.", "As illustrated, according to a preferred such a wavelet or pulse comprises a positive-going portion 802 a and negative-going portion 802 b ;", "the order of these two portions may be reversed to invert the pulse, thus facilitating generation of normal and inverted pulses in hardware.", "The pulses 802 have a nominal pulse repetition frequency, for example of the order of 100 MHz.", "However an additional one or more information data bits may be modulated onto signal 800 by varying the precise position (timing) of a pulse dependent upon the data to be transmitted.", "For various reasons bi-phase modulation of a UWB signal has been the preferred modulation of many applications.", "However by also varying the pulse position more data may be encoded onto the UWB signal thus increasing the available data rate for the options for forward error correction at a given data rate and hence the range of a signal.", "In practical schemes it is further preferable to dither the pulse position (in time) in a deterministic manner to further whiten the UWB signal spectrum and hence reduce the overall signal profile and/or facilitate staying within regulatory boundaries.", "Thus in addition to the precise timing of a pulse being dependent upon variable information data to be transmitted the pulse position may also be dependent upon a pseudo random or PN (pseudo noise) signal.", "Such a pseudo random sequence is preferably deterministic so that although apparently random once the sequence and start point is known it can be reconstructed in a deterministic manner at the receiver to allow this PN modulation to be effectively subtracted from the received signal or compensated for in other ways.", "[0093] Preferably the PN modulation is greater than the information data modulation since having a relatively small range of pulse positions about an expected pulse position (once the effects of PN modulation have been compensated for) simplifies demodulation of position-encoded data.", "In one preferred arrangement, described below, the positions a pulse can take in response modulation by information data are separated by one (or more generally an integral number) of reference (and input) UWB signal sampling intervals.", "Thus in some preferred embodiments a pulse 802 may take one of eight or 16 different positions in time (although other numbers of positions may be employed) and correlator 514 correlates the input signal with reference signals at all of these positions substantially in parallel to, in a parallel operation, locate the actual or most likely position of a received pulse.", "As shown in FIG. 8 according to a typical scheme the duration of a single doublet is typically between Sops and 100 ps and the correlator bank 514 performs parallel correlation operations over a time window 804 of approximately ins, thus identifying the pulse as being in one of around 16 overlapping positions.", "The skilled person will understand that the above timings, and the number of parallel multiply-accumulate units 600 of correlator 514 may be varied according to the requirements of a particular implementation or application.", "[0094] FIG. 9 a shows one example of an MAC frame 900 for use with the receiver 500 when receiving a signal of the type shown in FIG. 8 .", "This MAC frame is, however, provided merely for illustrative purposes and many other different frame formats may be employed.", "The example MAC frame 900 begins with a preamble sequence 902 comprising 32 bits of preamble data, for example pseudo random data for training.", "This is followed by a 4 byte header comprising a pseudo random sequence identifier and a pseudo random sequence seed (for identifying a starting point in a sequence), for example as a pair of 2 byte values.", "Different pseudo random sequences may be employed by different transmitters to help avoid collisions between transmitted UWB data signals.", "The header is preferably structured to give the appearance of noise, and may therefore include a whitening function—for example the pseudo random sequence identifier and seed may each be selected so that the header appears essentially random.", "The header is followed by payload data 906 which may also be whitened of a fixed or variable length, for example 128 bytes.", "[0095] FIG. 9 b schematically illustrates the positions of pilot tone pulses within a UWB signal 910 also comprising information-carrying pulses (not shown).", "In one arrangement one in every 100 pulses comprises a pilot tone pulse and, as can be seen from FIG. 9 b , these pilot tone pulses occur at regularly spaced intervals to provide a low-level pilot tone within the UWB signal regulatory spectral mask.", "Optionally the positions (in time) of the pilot tone pulses may be modulated to provide timing jitter, allowing more frequent or stronger pilot tone pulses within the spectral mask, although this is not necessary.", "[0096] FIGS. 10 a and 10 b illustrate an example of a UWB transmitter 1000 which may be employed to generate the information data modulated UWB signal 800 of FIG. 8 .", "The transmitter structure of FIG. 10 is provided by way of example only and other transmitter structures may also be employed to generate the UWB signal of FIG. 8 .", "For simplicity forward error coding arrangements are not explicitly shown in the figure.", "[0097] Referring to FIG. 10 a a clock 1002 operating at, for example, 250 MHz provides a clock signal to a chain of delay elements 1004 a - e each providing a delay of, in this example, 40 ps.", "The successively delayed versions of the clock signal are provided to each of a plurality of monostable pulse generators 1006 , each of which also receives an enable and control input from a controller 1008 .", "When enabled by the controller 1008 a monostable 1006 provides an output pulse doublet;", "the phase (normal or inverted) of the pulse doublet is also controllable by controller 1008 .", "The outputs from all of the monostable pulse generators 1006 are combined, in this example in summers 1008 and the combined output is provided to a transmit antenna 1010 .", "The controller 1008 receives a pseudo random sequence input from a pseudo noise generator 1012 , and also receives a data and control input 1014 , for example from a preceding forward error correction block and from a transmitter control processor.", "The data and control input receives information data to be transmitted by the transmitter and control signals such as a timing control signal to control when the transmitter is to transmit and/or pseudo noise sequence selection and start point control signals.", "The controller 1008 may comprise a state machine implemented in either software or dedicated hardware or a combination of the two.", "[0098] In operation the controller 1008 controls the timing of transmitted UWB pulses and the phase (normal or inverted) of these pulses by providing appropriate enable and phase control signals to the monostable pulse generators 1006 which are then triggered to provide output pulses at the corresponding time by the phase tapped clock from clock signal generator 1002 .", "[0099] Referring now to FIG. 10 b this shows an example of one implementation of a monostable 1006 for the transmitter of FIG. 10 a .", "The monostable comprises two pulse generators 1020 a, b , one providing a positive-going pulse, the other providing a negative-going pulse, outputs from these two pulse generators being combined in a summer 1022 to provide a pulse doublet output signal 1024 .", "Both of pulse generators 1020 a and 1020 b are controlled by a common enable line 1026 which when asserted enables the pulse generators to provide an output pulse in response to an input timing reference signal on line 1028 , but which when de-asserted disables the pulse generators from providing their outputs.", "In addition pulse generator 1020 b has a delay signal input 1030 which delays the production of its output pulse by two cycles to effectively invert the pulse doublet.", "Thus according to whether or not the delay input 1030 is asserted a pulse doublet comprising either a positive or negative-going pulse or a negative then positive-going pulse is provided.", "A UWB transmitter such as a transmitter 1000 of FIG. 10 may be combined with the UWB receiver of FIG. 5 to provide a UWB transceiver.", "In this case it is preferable that the UWB transmitter and receiver portions of the transceiver are synchronised to a common PRF clock to avoid self-collision, that is to avoid jamming reception of transmissions from a remote transmitter by local transmissions.", "[0100] Referring next to FIG. 11 , this shows details of the receiver 500 of FIG. 5 , and in particular details of the signal acquisition and locking system, including details of the reference signal capture signal.", "Like elements of those to FIGS. 5 and 6 are shown by like reference numerals.", "Broadly speaking the functions of the PSR lock acquisition module 604 are provided by a phase control processor and the functions of the pattern sequencer 602 of FIG. 6 are provided by a combination of a reference waveform data table and of a PSR sequence generator.", "[0101] As previously described the analog front end and A/D converter 504 provides a plurality of examples of a received UWB input signal in parallel to correlator 514 and each set of input signal samples is processed by a correlator comprising one of multiply-accumulate units 600 of correlator 514 to correlate the set of received samples in parallel with sets of reference signals representing differently delayed pulses.", "The sets of samples defining differently delayed versions of a referenced signal pulse are derived from a waveform of a pulse stored in a reference waveform data table 1100 .", "A reference received pulse is preferably stored in this table as a pulse shaped for each of a set of multi part components of the pulse together with data representing delay intervals between these multipath components, as shown in FIG. 11 b .", "However differently delayed versions of a pulse may be provided by accessing a common wave shape data store for the pulse.", "As shown in FIG. 11 b a reference or template waveform for a single received pulse having a plurality of multipath components comprises sample data 102 for a plurality of successive sample points of a multipath component of a pulse followed by delay data 1104 representing an interval between that multipath component of the pulse and the next multipath component.", "An input 1106 allows reference waveform data to be written into the referenced waveform data table 1100 .", "Reference waveform data is provided to the correlator 514 from the data table 1100 under control of a PSR sequence generator 1108 in synchronisms with a PRF clock input 1110 .", "[0102] A phase control processor 1112 provides a PRF clock to sequence generator 1108 and reference waveform data to data table 1100 .", "The phase control processor includes a processor and non-volatile program memory storing program code for pilot tone identification, to provide a software phase locked loop (PLL), for multipath component identification, and for template wave shape retrieval and storage.", "A clock 1114 provides a clock signal to the phase control processor and receives tracking data from processor 1112 comprising a time advance/retard signal for controlling the phase of the clock and a frequency increase/decrease for controlling the frequency of the clock when the phase needs to be consistently advanced/retarded.", "The clock 1114 is thus adjustable to track movement of the receiver with respect to the transmitter by means of systematic adjustment in the clock timing (which are generally small compared with the modulation).", "As described further below clock 1114 acts as a slave to a similar clock in a remote transmitter and thus acts as a link clock;", "typically it has a frequency in the range 50-200 MHz.", "[0103] The phase control processor 1112 provides a control output to a UWB transmitter 1116 , such as transmitter 1000 in FIG. 10 , to control the transmitter to provide a UWB signal from a transmit antenna 1118 for use in training receiver.", "The control processor 1112 also receives a starter frame input signal 1120 from a MAC state machine implemented in either hardware or software.", "The phase control processor 1112 further receives a set of inputs 1122 , one from each accumulator of correlator 514 , and a further input 1124 from the output of discriminator 612 .", "[0104] Broadly speaking, in operation the phase control processor 1112 programs the reference waveform data table 1100 with an initial, predetermined wave shape and then identifies the UWB signal pilot tone and runs a software phase lock loop to lock onto this tone to provide a time reference.", "The processor then uses this to identify the wave shape of a received pulse, including its multipath components.", "Optionally the processor 1112 may apply a Fast Fourier Transform (FFT) filter to remove narrow band interference.", "Broadly speaking to locate the multipath components of a transmitted pulse the phase control processor 1112 scans a sample window by shifting the phase of the PRF clock with respect to the internal clock from clock generator 1114 , integrating to obtain an average sampled data wave shape.", "Initially the multipath component with the strongest signal is identified and the shape of this multipath component of the pulse determined from the input data, and then the processor hunts for other multipath components both backwards and forwards from the strongest signal (because the direct line of sight pulse may not be the strongest).", "As previously described the correlator operates with blocks of eight or 16 samples and these blocks are effectively positional in time with respect to the link clock reference from clock generator 1114 .", "Preferably the multipath component pulse tracking procedure is repeated at a frequency in the order of kilohertz in order to track variations in the multipath channel and, in embodiments where implemented, to obtain physical location information relating to the receiver's position.", "In wired UWB transmission systems the multipath environment may be quasi static in which case a channel characterisation procedure such as that described above may only be applied at switch on or, for example, when the error rate increases above a threshold.", "[0105] In the arrangement shown in FIG. 11 a the phase control processor receives sampled input signal data via the correlator 514 .", "This simplifies the architecture of the receiver, although in other arrangements processor 1112 may receive sampled input signal data directly from analog front end 504 .", "To obtain sample input data from correlator 514 the input data may be correlated with a delta function such as a spike or impulse written into the wave form data table.", "[0106] FIG. 12 a shows a flow diagram explaining further the operation of the phase control processor 1112 of FIG. 11 a .", "To initial calibrate the receiver front end the control processor, at step S 1200 , instructs transmitter 1116 to local UWB pulses under control of the local clock generator 1114 .", "These pulses are received at a very high signal level and, moreover, processor 1112 knows when these pulses are transmitted and thus knows at what position in time the received input data is expected to comprise a transmitted pulse (taking account of the delay introduced by the separation between transmit antenna 1118 and receive antenna 502 (typically one or a few centimetres)).", "[0107] At step S 1202 processor 1112 programs wave form data table 1100 with a predetermined template, in particular an impulse, and hunts for the transmitted pulses by controlling the timing of PSR sequence generator 1108 .", "This is conveniently performed by inhibiting generation of a pseudo random sequence so that the phase of the output of generator 1108 may be varied by using the PSR seed as a phase offset adjust.", "Once the locally transmitted pulses are identified the wave shape of a pulse as received and digitised by analog front end 504 is read from correlator 514 and written into the referenced wave form data table to serve as an initial reference wave form.", "This in effect calibrates out phase and gain non-linearities in the receiver front end.", "Although the locally received signal is strong the wave shape data written into the data table 1100 may optionally comprise an average of a plurality of received pulses.", "[0108] Once this initial calibration has been performed the phase control processor 1112 has the more difficult task of frequency and phase locking onto a signal from a remote transmitter and of tracking this signal.", "Thus at step S 1206 processor 1112 controls the receiver to hunt for a signal at the pulse repetition frequency of the remote transmitter, that is at the pilot tone of the remote transmitter.", "The pilot tone frequency may not be known exactly but in preferred arrangements is limited to a small set of possible frequencies such as 50 MHz, 100 MHz, and 250 MHz and thus the receiver can pick each of these frequencies in turn to look for incoming UWB signals.", "The process of hunting for a signal at PRF is illustrated in FIG. 12 b .", "The receiver system first runs a correlation in a set of windows 1210 spaced by intervals at the PRF frequency, averaging the correlation results over a plurality of such windows and, if no significant correlation is found, slips the windows, at the same frequency, to a slightly delayed position 1212 as shown in timeline (ii) to repeat the correlation and averaging procedure until pulses at the PRF are found.", "Once the PRF frequency has been found, because the correlator 514 provides a plurality of outputs corresponding to a small range of delays either side of a desired time position it is straightforward to track variations in the PRF.", "The clock generator 1114 (and the equivalent in the transmitter) is preferably crystal controlled and thus relatively stable and varies only slowly compared with the kilohertz PLL tracking frequency.", "The more difficult task is to locate the remote transmitter PRF in the first place, particularly as a pilot tone pulse is transmitted for of the order of only one in 100 pulses, and because the UWB signal is relatively low level, especially at longer ranges.", "These difficulties are addressed by averaging over a relatively long period in order to identify the systematic pilot tone impulses which appear at fixed times and distinguish, for example, from other UWB pulses which appear effectively at random times.", "Depending upon the strength of the UWB signal and upon the range and transmit channel it may take as long as one or a few seconds to lock onto the relevant pilot tone as the correlator windows are slipped, which allows averaging over extremely large number of pulses.", "[0109] Once the phase control processor has locked onto the PRF of the remote receiver the processor can rely on the relative stability of clock generator 1114 and can thus rewrite the referenced wave form data table 1100 with an impulse and average over a plurality of pulses, typically between 100 and 1000 pulses, to determine the reference wave form for the transmit channel, and can then write this into the wave form data table.", "The number of pulses over which the signal needs to be averaged depends upon the range—one pulse may be enough at one metre and average of 10 4 pulses may be necessary at a range of 30 metres.", "Once the reference wave form for a first multipath component of a transmitted pulse has been identified the phase control processor 1112 can hunt backwards and forwards from this to identify the next multipath component of the pilot tone, and this can be repeated to determine data for a plurality of multipath components of a transmitted pulse.", "The number of multipath components for which data is acquired depends upon a trade off between acquisition time and system sensitivity (capturing energy from more multipath components facilitates greater sensitivity but takes longer to acquire).", "It will be appreciated that once the pulse shapes and delays for multipath components of a pulse have been located in time and samples stored tracking the variations of these over time is relatively straightforward and may be accomplished by periodically averaging over say 100 to 1000 pulses, for example by time multiplexing correlator in a similar way to that described below.", "[0110] FIG. 13 shows details of the reference wave form generation system.", "The PSR sequence generator 1108 receives control signals from the control processor 1112 comprising a pilot tone to control the timing of the reference wave form generation, and a starter frame signal and a sequence seed to control pseudo random sequence modulation for pulse position dithering, and provides a read timing control output 1302 to a pattern controller 1300 .", "Referring ahead to FIG. 15 a , this shows the received multipath components of two successively transmitted pulses 1500 and 1502 , each with a plurality of multipath components 1500 a - c , 1502 a - c .", "It can be seen that the multipath components 1500 a, b of pulse 1500 arrive before the start of pulse 1502 but that the multipath component 1500 c of pulse 1500 arrives between multipath components 1502 a and 1502 b of pulse 1502 .", "In order to correlate the received signal with a reference wave form corresponding to pulse 1500 (or 1502 ) the reference wave form data table 1100 should preferably be able to provide the appropriate multipath component of the pulses at the appropriate times even when these are interleaved as shown.", "Although this is not essential it is preferable in order to be able to retrieve energy from more multipath components of a received signal.", "[0111] Referring back now to FIG. 13 a pattern generator 1300 provides a plurality of outputs 1304 for providing reference wave forms corresponding to a plurality of transmitted pulses having overlapping multipath components.", "Thus, for example, if it is desired to process overlapping or interleaved multipath components from two successive transmitted pulses pattern controller 1300 provides two address outputs 1304 for addressing the wave form data table at appropriate times to provide portions of the reference wave form corresponding to the overlapping or interleaved portions of the multipath components.", "Thus referring again to the example of FIG. 15 a pattern controller 1300 provides a first address output for controlling data table 1100 to provide multipath components 1500 a, b, c and a second address output for addressing the table to provide the reference wave shapes for multipath components 1502 a, b, c at appropriate times.", "It will be appreciated that the number of address outputs of pattern controller 1300 depends upon the delay span of the number of significant multipath components of a pulse as compared with the inter-transmit pulse spacing.", "The reference wave form data table 1100 provides an output 1306 which comprises a time ordered combination of the multipath components of successfully transmitted components in the example of FIG. 15 a multipath components 1500 a , 1500 b , 1502 a , 1502 c , 1502 b and so forth.", "In a preferred arrangement a single set of outputs provides these multipath components in a time multiplexed fashion for use with correlator 514 also operating in a time sliced or multiplexed configuration.", "However an alternative arrangement is illustrated in FIG. 13 b in which data table 1100 has a plurality of sets of outputs, one for each transmitted pulse the receiver is concurrently able to process, which are combined in a summer 1310 and provided as a combined output for subsequent correlation.", "[0112] Referring in more detail to the parallel data outputs from the reference wave form data table, the data table memory is configured to provide a plurality of blocks of reference signal data in parallel, each block of data being delayed with respect to a previous block of data.", "A block of data may comprise, for example, eight or 16 sample values of the stored reference wave form, preferably defining a multipath component of a pulse such as a one of components 1500 a, b, c of FIG. 15 a .", "The blocks preferably overlap in time and in one arrangement each block is delayed from the previous block by one sample, 16 blocks defining 16 successfully delayed multipath pulse components being output in parallel.", "In this example this requires a BUS comprises 256 parallel outputs from reference output data table 100 , but the majority of these outputs may be provided simply by appropriate wiring since 16 blocks each of 16 samples, each delayed by a sample requires only 32 parallel sample value outputs.", "Each of these sample value outputs, it will be appreciated, may comprise a single or multi-bit value, depending upon whether or single or multi-bit A/D conversion is employed.", "Depending upon the duration of a multipath component of a pulse such as multipath component 1500 a of FIG. 15 a is stored within the reference wave form data table, a block of reference data may be added with zeros at either or both ends.", "The use of a reference wave form data table provides important benefits to the receiver system, in particular allowing use of a lower quality receiver analog front end than would otherwise be acceptable as the above described process of self-calibration, storing referenced wave form data table 1100 , can compensate for distortion within the receiver as previously described.", "[0113] In operation the PSR sequence generator 1108 is responsive to the pseudo random sequence employed for transmitting the data to control the read timing from the reference wave form data table to compensate for the pseudo random (but deterministic) time modulation imposed on the variable, information—dependent phase and position modulation.", "Pattern controller 1300 also provides an end of pattern output signal 1308 for use in resetting the correlator as described further below.", "[0114] FIG. 4 shows details of the configuration of the multiply-accumulate units of correlator 514 .", "The correlator comprises a plurality, in one configuration 16 , of multiply units 1400 each coupled to a respective accumulator 1402 .", "Each multiplier unit 1400 receives the same block 1404 of sampled input data, as illustrated comprising 16 successively delayed samples (either one or multi-bit values).", "Each multiply unit 1400 also receives a block of reference signal samples 1406 , in one configuration comprising 16 successive samples of the reference signal wave form, from data table 1100 , but each of blocks 1406 is successively delayed so that the sampled input data is correlated in parallel by multiplier units 1400 with portions of the referenced signal wave form spanning a range (as illustrated, 16) of successive time slices of the referenced wave form.", "The effect of this is to slide the sampled input data block or time slice along the referenced wave form until a correlation is found but it is easier in practice to firstly change the referenced wave form delay rather than the sampled received data delay, and secondly to perform a plurality of correlation in parallel rather than employ a single slide window.", "[0115] Each of multiply units 1400 comprises a multiplier to multiply each input data sample with the corresponding reference data sample and provide an output to the corresponding accumulator 1402 so that the accumulator accumulates a correlation value from all (in this case 16) correlation operations in parallel.", "Each accumulator has an output 1408 coupled to a partial correlation store 1410 for writing an accumulated correlation value into the store.", "Each accumulator also has an input 1412 from a read output of store 1410 to allow a partial correlation value written into the store to be read back from the store and added to a further correlation value in each respective accumulator.", "Writing of data into the store and reading of data from the store is controlled by the phase control processor 1112 .", "The partial correlation store 1410 comprises a plurality of sets of memory locations, each set of memory locations storing a set of partial correlation values, one from each multiply-accumulate module (T1 .", "T16).", "Storage is provided for as many sets of partial correlation values as is needed to process a desired number of transmitted pulses as overlapping or interleaved multipath components.", "Thus, for example, two sets of memory locations for partial correlation values are provided for storing partial correlation values where multipath components of two successively transmitted pulses overlap or interleave.", "[0116] Data from each of the plurality of memory locations of a set of partial correlation results is provided on an output 1414 to discriminator module 612 .", "Discriminator 512 also provides a memory clear output 1416 for clearing or setting to zero a set of partial correlation values, and receives an end of pattern signal 1308 from pattern controller 1300 .", "Discriminator 612 provides an output 1418 to subsequent forward error correction modules such as a Viterbi decoder.", "Although reference has been made to store 1410 storing partial correlation, once the correlation of a complete set of multipath components of a received signal pulse is complete the accumulated correlation values from outputs 1418 are written into store 1410 thus providing a set of complete correlation values, that is taking account of all multipath components it has been decided to process, and these complete correlation values are available to the discriminator 612 via BUS 1414 .", "[0117] To illustrate the operation of the correlator 514 of FIG. 14 it is helpful to refer to FIG. 15 a .", "Broadly speaking the procedure is to correlate (accumulate) the first received multipath component 1500 a and to dump this into store 1410 , and then to correlate the next multipath component 1500 b , also accumulating the previously stored partial correlation for multipath component 1500 a by reading this from store 1410 adding this to the partial correlation value of multipath component 1500 b , and the total accumulated set of correlation values is then written back into store 1410 .", "This process is continued until a multipath component of a subsequent pulse is encountered, in this case multipath component 1502 a of pulse 1500 .", "The pattern controller 1300 of FIG. 13 then controls the reference wave form data table 1100 to provide a pulse shape appropriate for correlating with multipath component 1502 a and following the correlation operation the result of this correlation is dumped into a separate set of memory locations within store 1410 , this set of memory locations being allocated to the second pulse.", "The correlation operation for multipath components of the received signal continues with the partial correlation results being written into the set of memory locations for either the first or second pulse as appropriate, the pattern generator controlling the wave form data table to generate a reference wave shape for the appropriate multipath component.", "Thus continuing with the example of FIG. 15 a multipath component 1500 c of the first pulse is next accumulated with the partial correlation value read from store 1410 for the first pulse and dumped back into store 1410 .", "In this case this is the final processed multipath component pulse of 1500 though the accumulated correlation values in store 1410 for the first pulse can then be taken as complete correlation values and processed by discriminator 612 .", "The signal indicating that the complete set of multipath components has been correlated is provided by pattern controller 1300 since this controller is able to determine that the final stored multipath component has been processed.", "However correlation of pulse 1502 continues with multipath component 1502 b and when the first multipath component of a third pulse (is not shown in FIG. 1500 a ) received the set of partial correlation values which was previously used for pulse 1500 (and which was cleared by discriminator 612 after the complete correlation values for pulse 1500 were processed) is available for use for accumulating correlation values for this third pulse.", "[0118] FIG. 15 b shows, diagrammatically, the correlation of a multipath component 1510 a of a received UWB signal pulse 1510 with a set of referenced pulses 1512 a, b of which, for clarity, only two are shown.", "The referenced signal pulses are time shifted to either side of the received multipath component 1510 a and correlation with each of these referenced signal pulses provides a correlation value as schematically illustrated in graph 1514 .", "The shape of this curve, and the height and width of its peak may alter depending upon the received signal and referenced signal shape.", "In FIG. 15 b a set of (full) correlation values output from storage 1410 to discriminator 612 on BUS 1414 is diagrammatically illustrated by bar chart 1516 in which each bar 1518 represents an accumulated correlation value for one of the delayed versions of the referenced signal multipath component 1512 .", "It can be seen that most of the accumulated correlation values are close to a mean level 1520 but one of the accumulated values represented by bar 1522 is significantly different from the others.", "This represents the most likely pulse position;", "the bars 1524 , 1526 to either side of it represents next most probable pulse positions.", "Bar 1522 a is significantly greater than the average 1520 which applies a positive correlation (normal pulse) whilst bar 1522 b has a correlation value which is significantly less (more negative) than the average which implies a negative correlation that is an inverted received signal pulse as compared with the reference.", "Thus the correlator of FIG. 14 b is able to co-determine both the likely position (in time) of a received signal pulse and also the phase (normal or inverted) of the pulse and hence to co-determine information data modulated to both pulse position and pulse phase simultaneously.", "The use of both position and phase simultaneously to encode information data significantly enhances the information data carrying capacity of the system.", "[0119] In the above described system the correlator is employed for correlating successive multipath components of received signal pulses.", "However essentially the same arrangement can also be used for accumulating relation values for successively transmitting impulses carrying the same data.", "In other words a transmitter and/or receiver may employ redundancy, using two or more transmit pulses to carry substantially the same data, at the receiver processing these as though they were merely multipath components of a single pulse.", "This reduces the effective data rate (halving data rate where two pulses are received instead of one to transmit a given symbol) but potentially increases the range of a transmission system by providing greater energy per transmitted symbol.", "Such an arrangement may be employed adaptively, reducing the data rate but increasing reliability where transmission conditions are difficult or at the edge of range of a system.", "The reduction in effective data rate may be partially compensated for by increasing the pulse repetition frequency, providing that operation within the desired regulatory spectral envelope is maintained;", "the transmit power may also be adaptively controlled to facilitate this.", "[0120] No doubt alternatives will occur to the skilled person.", "It will be understood that the invention is not limited to the described embodiments and encompasses modifications apparent to those skilled in the art lying within the scope of the claims appended hereto.", "[0121] Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent.", "The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.", "[0122] In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.", "[0123] The entire disclosures of all applications, patents and publications, cited herein and of corresponding Great Britain application No. 0316897.8, filed Jul. 18, 2003, and U.S. Provisional Application Ser.", "No. 60/518,344, filed Nov. 10, 2003, are incorporated by reference herein.", "[0124] The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.", "[0125] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions." ]
BACKGROUND OF THE INVENTION The invention relates to an installation for transporting objects, in particular items of clothing hanging on clothes hangers. Such installations transport the objects on conveying paths by means of a transporting roller, containing two parallel spaced-apart flanges on the end sides and a central part located therebetween as well as a through-passage opening leading through the center between the flanges and the central part, the central part having at least one peripheral, annular circumferential part which can rotate separately from the two flanges, and the two flanges being connected to one another and to the circumferential part such that, in the case of the circumferential part rotating as a result of bearing on the conveying path, the two flanges are in a rest state irrespective of the rotation, a hook-like carrier element for an object which is to be transported passing through the through-passage opening and projecting from the latter by way of its free end. The transporting roller of the abovementioned transporting installation is known from EP 10 13 569 A1 and is designed in order to avoid the smoothing effect which arises with a build-up of at least two transporting rollers. BRIEF SUMMARY OF THE INVENTION It is an object of the present invention to provide an installation which is intended for transporting objects of the type mentioned below and ensures, by straightforward means, the reliable transportation of objects which are to be transported on conveying paths. Accordingly, the invention provides that the conveying path comprises a fixed rolling ridge with a transporting-roller running track on its top side, the transporting roller riding on the rolling ridge, the two flanges of the transporting roller engaging laterally around the rolling ridge, and the circumferential part of the transporting roller engaging with transporter-roller running track, and that guided along the rolling ridge, spaced apart laterally from the same at least corresponding to the thickness of the flange projecting there, is a comb-like conveying mechanism, of which the gaps or clearances are dimensioned for the engagement of the free end of the hook-like carrier element. This manner of transporting-roller movement allows a straightforward design of the transporting means for the transporting roller in the form of a comb-like conveying mechanism which can be moved along the conveying path and in the gaps of which the free end of the hook-like carrier element for the goods which are to be transported can be accommodated in order for the transporting roller to be carried along. The comb-like conveying mechanism is advantageously connected to a link chain running parallel to the conveying path, in particular a laterally curved chain of a drive arrangement. The comb-like conveying mechanism preferably comprises tines in the form of regularly spaced-apart carry-along pins which extend perpendicularly to the through-passage opening of the transporting roller and perpendicularly to the transporting-roller running track, in order to provide the highest possible clearance for the reliable engagement of the free end of the hook-like carrier element. According to a particularly advantageous development of the invention, the rolling ridge, provided by the transporting-roller running track, is formed as part of a profile rail, in which the link chain is guided. This profile rail preferably has a generally C-shaped cross section, an upwardly oriented edge of the C-profile rail forming the transporting-roller running track. The comb-like conveying mechanism preferably spans to the full extent, by way of its tines, the gap between the mutually facing edges of the C-profile rail for the purposes of providing a clearance which is bounded at the top and bottom, in order for the free end of the hook-like carrier element, and thus the transporting roller, to be reliably secured throughout the conveying displacement. An advantageous development of the invention provides that the installation has a location for supplying or introducing the transporting roller(s) into the conveying path, having a downwardly sloping section which opens out laterally into the conveying path and comprises a fixed rolling ridge with a transporting-roller running track on its top side, said rolling ridge opening out into the rolling ridge of the conveying path, there being provided in the downwardly sloping section, on which the transporting roller(s) is or are conveyed to the conveying path by the action of gravitational force, an arrangement for restraining the transporting roller(s), which can be released synchronously with the presence of a gap of the conveying mechanism in the supply location, with account being taken of the period of time taken for the respective transporting roller to come into contact with this gap. This object is achieved by the features set forth below. Advantageous developments of the invention are also specified below. At this introduction location, or generally in the case of diverters which open out into the conveying path, the gap sequence of the conveying mechanism is coordinated with the timing of the respective diverter. Provided for this purpose is a corresponding clock generator, for example in the form of a gearwheel, which engages in the gaps of the comb-like conveying mechanism, or the spaced-apart tines thereof, and controls the diverter in a correspondingly synchronous manner. The restraining arrangement at the abovementioned location for introducing transporting rollers into the conveying path preferably comprises a restraining pin for releasing a leading transporting roller and a further restraining pin for restraining trailing transporting rollers, it being possible for the restraining pins to be moved in the direction of their longitudinal axes between a restraining position in front of the respective transporting roller and a release position, in which they are disengaged from the respective transporting roller. The restraining pins can preferably be moved essentially perpendicularly to the transporting-roller running track of the downwardly sloping section. The invention further provides that the conveying path comprises at least one ejecting location or discharging line which branches off from it and has a downwardly sloping section, which has a fixed rolling ridge with a transporting-roller running track on its top side and on which the transporting roller(s) is or are conveyed to a collecting location by the action of gravitational force, the ejecting location comprising a diverter which can optionally be brought up to the conveying path in order to transfer the transporting roller(s) to the downwardly sloping section of the ejecting location, with the free end of the hook-like carrier element passing through the through-passage opening thereof, being disengaged in the process. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS The invention is explained in more detail, by way of example, hereinbelow, with reference to the drawing, in which: FIG. 1 shows, schematically, an embodiment of an installation for transporting items of clothing hanging on clothes hangers with single-stage sorting, FIG. 2 shows, schematically, an embodiment of an installation for transporting items of clothing hanging on clothes hangers, with two-stage sorting, FIGS. 3 to 5 show an embodiment of the introduction location at which items of clothing hanging on clothes hangers are introduced into the conveying path of the installation of FIGS. 1 and 2, FIG. 3 showing a leading transporting roller being separated off from trailing transporting rollers, FIG. 4 showing the transfer of the transporting roller separated according to FIG. 3, and FIG. 5 showing the beginning of the next separating operation once the leading transporting roller has been transferred, FIG. 6 shows an ejecting location of the installation of FIGS. 1 and 2, at which transporting rollers with items of clothing hanging on clothes hangers are ejected from the conveying path, FIG. 7 shows a schematic perspective illustration of a transporting roller of the installation of FIGS. 1 and 2 on the conveying ridge of the conveying path of the installation, FIG. 8 shows a front view of the transporting roller from FIG. 7 in the direction transverse to the conveying path, and FIG. 9 shows a cross section through the transporting roller along line I—I from FIG. 7 without the carrier element, conveying path and barcoding, but with cutouts and a securing part. DETAILED DESCRIPTION OF THE INVENTION Since the conveying principle according to the invention of an installation for transporting objects is based on a specifically configured transporting roller with fixed side parts and a rotatable annular part in the center, this transporting roller, which is described in more detail, for example, in EP 1 013 569 A1, will be explained in more detail hereinbelow with reference to FIGS. 7, 8 and 9 , in which the same parts with the same functions have the same designations. In FIGS. 7 and 8, the transporting roller 1 essentially comprises two parallel disk-like outer flanges 2 , 3 on the end sides in each case, the elements referred to above as fixed side parts, and a central part 4 located therebetween, the element referred to above as a rotary annular part. Provided along the associated center axis 5 is a through-passage opening 6 , in which a securing part 7 is optionally located. The transporting roller 1 is connected, via its through-passage opening 6 , to an arcuate carrier element or hook 8 of a hanger, on which items of clothing are conveyed in the transporting installation in question. For this purpose, the central part 4 of the transporting roller 1 bears on a rolling ridge, which will be explained in more detail at a later stage in the text, of a conveying path of the transporting installation, the inclination of the same making it possible for the transporting roller 1 to move. As can be gathered from FIG. 8, the carrier element 8 , in the form of a clothes-hanger hook, bears on the ends of the securing-part 7 in each case. The securing part 7 is a hollow-cylindrical bushing, of which the end regions are bent outward in each case by riveting 24 , 25 . The inner construction of the transporting roller 1 cannot readily be seen from FIGS. 7 and 8. The transporting roller 1 is thus shown in section in FIG. 9 . The central part 4 , which is located between the first flange 3 and the second flange 2 , has an annular web 11 , which forms part of the first disk-like flange 3 , is directed towards the second flange 2 , is extended on one side and has a central bore as through-passage opening 6 of standard diameter. The annular web 11 has a slightly inclined outer surface from its point of attachment to the first flange 3 to its free end region 20 , which is flattened perpendicularly to the center axis 5 . The slightly inclined outer surface of the annular web 11 , at the same time, constitutes the inner running surface 12 for the rolling bodies 13 , 14 of a rolling-contact bearing. A multiplicity of rolling bodies are usually necessary for a reliably functioning rolling-contact bearing. The inner running surface 12 has, in the center, an encircling groove-like depression 18 , which is adapted in an accurately dimensioned manner to the outer surfaces of the rolling body 13 , 14 and in which the rolling bodies 13 , 14 can move. On the outside, the rotatable circumferential part 15 , in the form of an outer ring, encloses the rolling bodies 13 , 14 at a radial distance from the inner running surface 12 , and it has a disk-like side wall 21 which is angled perpendicularly to the center axis 5 and is located on the smaller-diameter side of the annular web 11 . In the direction of the side of the larger annular-web diameter or of the first flange 3 , the outer ring 15 is preferably open, inter alia for assembly reasons. The outer ring 15 is provided in each case with a slight amount of slot-induced play 16 , 17 in relation to the inner surfaces 23 , 22 of the first and of the second flanges 3 , 2 . On its paraxial inner running surface 10 , the outer ring 15 may likewise contain an encircling groove-like depression 19 , which is likewise adapted to the surfaces of the rolling body 13 , 14 . The second disk-like flange 2 is firmly secured against the free flattened end region 20 of the annular web 11 by the securing part 7 , the securing part 7 pressing the second flange 2 onto the end region 20 of the annular web 11 by rigid riveting 24 , 25 . The hollow-cylindrical securing part 7 has formed through it a channel 26 , into which the hook 8 of a clothes hanger is introduced and pushed through until that position of the hook 8 which is shown in FIG. 8 is reached. In the simplest case (FIGS. 7 and 8 ), the second flange 2 may be provided with barcodings 37 . In FIG. 9, the second disk-like flange 2 has hole-like cutouts 27 , 28 in which, instead of the barcodings 37 shown in FIGS. 7 and 8, coding arrangements having electrical and electronic components (these arrangements not being shown) can be fastened. The coding arrangements may be, for example, radially or circularly arranged inductive, magnetic and/or capacitive arrangements or pins, made of a material differing from the flange material, in order for it to be possible to gather the storage information therefrom. The cutouts 27 , 28 , however, may also constitute an annular groove in which it is possible to secure electrical components, coupled with ROM and/or RAM memory modules, which have been introduced therein. As can be gathered from FIGS. 7 to 9 , in the transporting roller 1 , the central part 4 in other words has at least one peripheral annular circumferential part 15 which can be rotated separately from the two flanges 2 , 3 , the two flanges 2 , 3 being connected to one another and to the circumferential part 15 such that, in the case of the circumferential part 15 rotating as a result of bearing on the conveying path, the two flanges 2 , 3 are in a rest state irrespective of the rotation. This configuration of the transporting roller is the basis for the design according to the invention, which will be explained hereinbelow, of the transporting installation for transporting, in particular, items of clothing hanging on clothes hangers. In particular, this transporting roller, with fixed outer elements and a rotating inner element, allows a transporting means or a pushing arrangement to act directly on the transporting roller. A corresponding transporting installation will be explained hereinbelow with reference to FIGS. 1 to 6 . FIGS. 1 and 2 show, schematically, in general terms, two embodiments of the arrangement according to the invention for transporting, in particular, items of clothing hanging on clothes hangers, the installation according to FIG. 1 being provided for single-stage sorting, while the installation according to FIG. 2 is provided for two-stage sorting. The transporting installation shown in FIG. 1 comprises an open-circuit conveying path 41 with a supply location 42 at one end for unsorted goods and with an end 43 for the removal of sorted goods. Provided between the supply location 42 and the removal end 43 of the conveying path 41 are a plurality of parallel discharging lines, of which merely four discharging lines 44 to 47 are illustrated in FIG. 1 . The discharging lines 44 to 47 , on the inlet side, branch off from the conveying path 41 via diverters 48 to 51 . On the outlet side, the discharging lines 44 to 47 pass over into the conveying path 41 again via diverters 52 to 55 . Between their inlet and their outlet, the discharging lines 44 to 47 are each provided with a downwardly sloping section, in order to transfer the incoming goods to the outlet-side diverters 52 to 55 on account of the gravitational force thereof. The discharging lines provide a sorting means which is referred to here as being single-stage because the goods only pass through one or more of the discharging lines once. In contrast to this, FIG. 2 shows a modified design of the transporting installation of FIG. 1, with two-stage sorting of goods. In addition to the design with a plurality of discharging lines which is shown in FIG. 1, the transporting installation according to FIG. 2 comprises a return line 56 , which is connected to the conveying path 41 , via an inlet diverter 57 , downstream of the discharging lines 44 to 47 . In addition, the return line 56 is connected to the conveying path 41 upstream of the discharging lines 44 to 47 and downstream of the supply location 42 . For the purposes of transporting goods, the return line 46 likewise comprises a downwardly sloping section, which runs in the opposite direction to the downwardly sloping sections of the discharging lines 44 to 47 . Formed at the end of each discharging line 44 to 47 is a collecting location or a transfer station 58 , by means of which goods coming in via the discharging lines 44 to 47 are collected and can be introduced into the conveying path 41 again in a specific manner. A similar collecting location 62 is located at the end of the return line 56 . Details of the transporting installation according to FIGS. 1 and 2 can be gathered from FIGS. 3 to 5 , which show the installation in detail in the region of the supply location 42 . Accordingly, the conveying path 41 and the supply location 42 comprise a respective profile rail 63 , 64 with a generally C-shaped cross section. On account of the C-shaped cross section, the profile rail 63 , 64 is closed all the way round apart from a respective gap 65 , 66 , which is bounded by the mutually facing edges of the C-shaped profile rail. Of these two edges, the bottom or upwardly oriented edge is formed as a transporting-roller running track 67 , 68 . The running track 67 or 68 thus forms the top side of a respective rolling ridge 69 , 70 , which forms one of the mutually facing ends of the C-shaped profile rail 63 with the respective gap 65 , 66 located therebetween. The transporting roller 1 , which is shown in FIGS. 7 to 9 , FIGS. 3 to 5 showing four running-track rollers 1 , 1 ′, 1 ″ and 1 ′″, rides on said rolling ridge 69 , 70 , the central part 4 of each transporting roller being in rolling contact with the running track 67 , 68 , while the lateral, stationary flanges 2 , 3 of each transporting roller engage over the rolling ridge 69 , 70 on both sides, as a result of which the respective transporting roller is guided laterally. Additional lateral guidance for the transporting roller 1 is provided by the guide ridge 71 , 72 , which is located opposite the respective rolling ridge 69 , 70 , constitutes that end of the respective C-shaped profile 63 , 64 which is located opposite the rolling ridge 69 , 70 and engages between the two flanges 2 , 3 , albeit without coming into contact with the central part 4 of the transporting roller 1 . Interacting with one another, the rolling ridge 69 , 70 and the guide ridge 71 , 72 thus provide lateral positive guidance for the transporting roller 1 , with the result that said roller cannot pass laterally out of the profile rail 63 , 64 although, in the gap 65 , 66 of the latter, it can run in an essentially resistance-free manner, i.e. under rolling resistance, on the running track 67 , 68 . Added to this rolling resistance at most, when the goods hanging on the transporting rollers pivot laterally, is a brief contact resistance between the two flanges 2 , 3 and the ridges 69 to 72 . In order to convey the transporting rollers on the essentially horizontally running conveying path 41 or in the profile rail 63 , use is made of a link chain 73 , which is guided via gearwheels, spaced apart in the running direction, outside (as is shown) or alternatively within, the profile rail 63 and is driven via an electromotive drive (not shown). The motion of the link chain 73 is transmitted to the transporting rollers with the aid of a comb-like conveying mechanism 74 , which runs along the gap 65 in the profile rail 63 . The comb-like conveying mechanism is connected to the link chain 73 by a connecting means (not shown) which is arranged in the profile rail and, with the link chain 73 located on the outside, engages through a slot in the profile rail 63 (said slot not being shown either) located opposite the gap 65 . The tines of the comb-line conveying mechanism 74 run perpendicularly to the through-passage opening 6 of the transporting rollers running in the gap 65 and perpendicularly to the transporting-roller running track 68 . In the exemplary embodiment illustrated, the tines of the comb-like conveying mechanism are formed as uniformly spaced-apart carry-along pins for the free end of the hook-like carrier element 8 of the goods-securing part, e.g. in the form of a clothes hanger. The interspaces or clearances 78 of the tines or carry-along pins, of which two pins are designated 75 and 76 in FIGS. 3 to 5 , and the height of these spaces are selected such that the free end of the carrier element, coming from the supply location 42 , can pass into these spaces 78 and is then carried along together with the respective transporting roller and the goods hanging thereon. On account of the specific construction of the transporting roller, that flange 2 or 3 of the transporting roller which is oriented toward the interior of the profile rail engages with at least the two carry-along pins 75 , 76 defining the accommodating clearance, without relative movement, and the associated friction, occurring between these parts during the conveying movement, because these flanges are fixed and do not accompany the rolling movement of the rolling part of the transporting roller, as has been explained above with reference to FIGS. 7 to 9 . The operation of transporting rollers entering into the conveying path 41 via the supply location 42 will be explained hereinbelow with reference to FIGS. 3 to 4 . As has been indicated above, the supply location 42 is defined by a profile rail 64 with a C-shaped cross section corresponding to the profile rail 63 . At least in the region of the supply location 42 , that is to say at the location where the profile rail 64 opens out laterally into the profile rail 63 , the profile rail 64 has a downwardly sloping section, of which the lowermost point is situated at the location at which the profile rail 64 opens out into the profile rail 63 . On account of this downwardly sloping section, the transporting rollers, with the clothes hangers hanging on them, which are fed into the profile rail 64 at the other end of the latter move down the downwardly sloping section under the action of gravitational force. In order for the transporting rollers 1 to 1 ′″ to be fed into the conveying path 41 or the profile rail 63 separately and at the appropriate point in time, that is to say when a predetermined clearance 78 of the comb-like conveying mechanism 74 reaches the location at which the profile rail 64 opens out into the profile rail 63 , a restraining arrangement is formed at the supply location 42 upstream of the opening-out location. This restraining arrangement comprises two restraining pins 84 and 85 , which are spaced apart one behind the other in the longitudinal direction of the profile rail 64 . The restraining pins 84 and 85 can have their axial position adjusted in a manner known per se by means of drive cylinders 86 , 87 , with the aid of which the restraining pins 84 , 85 can optionally be displaced into a position in front of a respective transporting roller. In FIG. 3, the front restraining pin 84 , as seen in the conveying direction in the profile rail 64 , is located in front of the leading transporting roller 1 , with the result that the latter butts against the restraining pin 84 , while the rear restraining pin 85 is located on the rear side of said transporting roller 1 , in front of the next, trailing transporting roller 1 ′. The leading transporting roller 1 has thus already been separated off from the trailing transporting rollers 1 ′, 1 ″ and 1 ′″, of which the roller 1 ′ is restrained by the rear restraining pin 85 , while the following transporting rollers 1 ″, 1 ′″ butt against one another and against the transporting roller 1 ′. Starting from the position in FIG. 3, the next step is for the front restraining pin 84 then to be drawn back from its position in front of the transporting roller 1 when a restraining pin 82 a , which is concealed in FIG. 3, is situated immediately in front of the location at which the profile rail 64 opens out into the profile rail 63 . For this purpose, the motion of the link chain 73 is synchronized, in a manner which is not illustrated specifically, with the actuation of the drive cylinder 86 for the front restraining pin 84 , e.g. by means of a synchronization gearwheel 79 which interacts with the link chain 73 , with account being taken of the time which is required for the released transporting roller 1 to run out of its restrained position, with the restraining pin 84 extended, to the location at which the profile rail 64 opens out into the profile rail 63 . There, the free end of the hook-like carrier element 8 , which is oriented inward (toward the interior of the profile rail 63 .) and projects from the through-passage opening 6 of the transporting roller, engages in the clearance 78 of the conveying mechanism 74 , which is situated at the opening-out location, with the result that the transporting roller is carried along via the carrier element. The next step, as is shown in FIG. 5, is for a further transporting roller 1 ″″ to run up and thus form the last transporting roller of the abutting transporting rollers 1 ′, 1 ″, 1 ′″, 1 ″″, of which the now leading transporting roller 1 ′ comes into abutment against the restraining pin 84 , which has now been extended again, once the rear restraining pin 85 has been retracted. In order to separate the now leading transporting roller 1 ′, the rear restraining pin 85 is extended again, and the operation of separating the leading transporting roller, the beginning of which is shown in FIG. 3, begins anew, as has been explained above. A transporting-installation configuration which is similar to the supply location is located, for example, at the transition from the discharging lines 44 to 47 to the conveying path 41 . At this location, the diverters 52 to 55 , as appropriate, are formed in a manner corresponding to the profile rail 64 at the supply location 42 . FIG. 6 shows a location for moving the transporting rollers out of the conveying path 41 onto one of the discharging lines, for example the discharging line 44 according to FIGS. 1 and 2. The discharging line 44 , in turn, comprises a profile rail 88 , which is curved similarly to the profile rail 64 and opens out into the conveying path. The profile rail 88 likewise opens out into the profile rail 63 , which defines the conveying path 41 . The profile rail 88 , however, serves for ejecting transporting rollers, and the goods hanging on them, from the conveying path 41 . Since not every transporting roller is to be transferred from the profile rail 63 to the profile rail 88 , a diverter is formed between these two profile rails 63 and 88 . This diverter comprises a rolling-ridge section 89 , which is articulated pivotably on the profile rail 63 , and a guide-ridge section 90 , which is articulated pivotably on the profile rail 63 . In the pivoted-in state, the rolling-ridge section 89 forms part of the rolling ridge 69 of the profile rail 63 , while, in the pivoted-in state, the guide-ridge section 90 forms part of the guide ridge 71 of the profile rail 63 . In the pivoted-out state, or when the diverter is positioned such that transporting rollers are to be ejected from the profile rail 63 onto the profile rail 88 , the rolling-ridge section 89 interrupts the rolling ridge 69 and the guide-ridge section 90 interrupts the guide ridge 71 , and these sections 89 , 90 of the diverter, in the pivoted-out position, then adjoin a respective rolling ridge 91 and a guide ridge 92 of the profile rail 88 , as a result of which transporting rollers arriving at the diverter are ejected into the profile rail 88 . In order to adjust the sections 89 , 90 of the diverter, use is made of a diverter-switching mechanism 93 , which is merely illustrated schematically as a C-shaped clamp. As soon as a transporting roller located on the diverter leaves the diverter, it is transported by the downward slope on the discharging line, under the action of gravitational force, to a collecting location. LIST OF DESIGNATIONS 1 Transporting roller 2 Second flange 3 First flange 4 Central part 5 Center axis 6 Through-passage opening 7 Securing part 8 Carrier element 11 Annular web 12 Inner running surface 13 Rolling body 14 Rolling body 15 Circumferential part 16 Play 17 Play 18 First groove-like depression 19 Second groove-like depression 20 Free end region 21 Disk-like side wall 22 Inner surface 23 Inner surface 24 Riveting 25 Riveting 26 Channel 27 Cutout 28 Cutout 36 Latching cutout 37 Coding arrangement 41 Conveying path 42 Supply location 43 Removal end 44 Discharging line 45 Discharging line 46 Discharging line 47 Discharging line 48 Diverter 49 Diverter 50 Diverter 51 Diverter 52 Diverter 53 Diverter 54 Diverter 55 Diverter 56 Return line 57 Diverter 58 Collecting location 59 Collecting location 60 Collecting location 61 Collecting location 62 Collecting location 63 Profile rail 64 Profile rail 65 Gap 66 Gap 67 Running track 68 Running track 69 Rolling ridge 70 Rolling ridge 71 Guide ridge 72 Guide ridge 73 Link chain 74 Conveying mechanism 75 Carry-along pin 76 Carry-along pin 78 Clearance 79 Synchronization gearwheel 84 Restraining pin 85 Restraining pin 86 Drive cylinder 87 Drive cylinder 88 Profile rail 89 Rolling-ridge section 90 Guide-ridge section 91 Rolling ridge 92 Guide ridge 93 Diverter-switching mechanism
An installation for transporting objects, in particular items of clothing hanging on clothes hangers, on conveying paths of a transporting roller, in particular a roller having two parallel spaced-apart flanges on end sides thereof and a central part located therebetween, as well as a through-passage opening extending through a center thereof disposed between the flanges and the central part. The central part has at least one peripheral, annular circumferential part which can rotate separately from the two flanges, so that when the circumferential part rotates as a result of bearing on one of the conveying paths, the two flanges remain in a rest state irrespective of the rotation of the circumferential part. A hook-like carrier element is provided for an object which is to be transported, passing through the through-passage opening and projecting from the latter by way of its free end. The conveying path includes a fixed rolling ridge with a transporting-roller running track on its top side, so that the transporting roller rides on the rolling ridge with the two flanges of the transporting roller engaging laterally around the rolling ridge, and with the circumferential part of the transporting roller engaging the transporting-roller running track. A comb-like conveying mechanism is guided along the rolling ridge, spaced apart laterally from the same at least corresponding to the thickness of the flange projecting there. The comb-like conveying mechanism is provided with gaps which are dimensioned for engagement with the free end of the hook-like carrier element.
Condense the core contents of the given document.
[ "BACKGROUND OF THE INVENTION The invention relates to an installation for transporting objects, in particular items of clothing hanging on clothes hangers.", "Such installations transport the objects on conveying paths by means of a transporting roller, containing two parallel spaced-apart flanges on the end sides and a central part located therebetween as well as a through-passage opening leading through the center between the flanges and the central part, the central part having at least one peripheral, annular circumferential part which can rotate separately from the two flanges, and the two flanges being connected to one another and to the circumferential part such that, in the case of the circumferential part rotating as a result of bearing on the conveying path, the two flanges are in a rest state irrespective of the rotation, a hook-like carrier element for an object which is to be transported passing through the through-passage opening and projecting from the latter by way of its free end.", "The transporting roller of the abovementioned transporting installation is known from EP 10 13 569 A1 and is designed in order to avoid the smoothing effect which arises with a build-up of at least two transporting rollers.", "BRIEF SUMMARY OF THE INVENTION It is an object of the present invention to provide an installation which is intended for transporting objects of the type mentioned below and ensures, by straightforward means, the reliable transportation of objects which are to be transported on conveying paths.", "Accordingly, the invention provides that the conveying path comprises a fixed rolling ridge with a transporting-roller running track on its top side, the transporting roller riding on the rolling ridge, the two flanges of the transporting roller engaging laterally around the rolling ridge, and the circumferential part of the transporting roller engaging with transporter-roller running track, and that guided along the rolling ridge, spaced apart laterally from the same at least corresponding to the thickness of the flange projecting there, is a comb-like conveying mechanism, of which the gaps or clearances are dimensioned for the engagement of the free end of the hook-like carrier element.", "This manner of transporting-roller movement allows a straightforward design of the transporting means for the transporting roller in the form of a comb-like conveying mechanism which can be moved along the conveying path and in the gaps of which the free end of the hook-like carrier element for the goods which are to be transported can be accommodated in order for the transporting roller to be carried along.", "The comb-like conveying mechanism is advantageously connected to a link chain running parallel to the conveying path, in particular a laterally curved chain of a drive arrangement.", "The comb-like conveying mechanism preferably comprises tines in the form of regularly spaced-apart carry-along pins which extend perpendicularly to the through-passage opening of the transporting roller and perpendicularly to the transporting-roller running track, in order to provide the highest possible clearance for the reliable engagement of the free end of the hook-like carrier element.", "According to a particularly advantageous development of the invention, the rolling ridge, provided by the transporting-roller running track, is formed as part of a profile rail, in which the link chain is guided.", "This profile rail preferably has a generally C-shaped cross section, an upwardly oriented edge of the C-profile rail forming the transporting-roller running track.", "The comb-like conveying mechanism preferably spans to the full extent, by way of its tines, the gap between the mutually facing edges of the C-profile rail for the purposes of providing a clearance which is bounded at the top and bottom, in order for the free end of the hook-like carrier element, and thus the transporting roller, to be reliably secured throughout the conveying displacement.", "An advantageous development of the invention provides that the installation has a location for supplying or introducing the transporting roller(s) into the conveying path, having a downwardly sloping section which opens out laterally into the conveying path and comprises a fixed rolling ridge with a transporting-roller running track on its top side, said rolling ridge opening out into the rolling ridge of the conveying path, there being provided in the downwardly sloping section, on which the transporting roller(s) is or are conveyed to the conveying path by the action of gravitational force, an arrangement for restraining the transporting roller(s), which can be released synchronously with the presence of a gap of the conveying mechanism in the supply location, with account being taken of the period of time taken for the respective transporting roller to come into contact with this gap.", "This object is achieved by the features set forth below.", "Advantageous developments of the invention are also specified below.", "At this introduction location, or generally in the case of diverters which open out into the conveying path, the gap sequence of the conveying mechanism is coordinated with the timing of the respective diverter.", "Provided for this purpose is a corresponding clock generator, for example in the form of a gearwheel, which engages in the gaps of the comb-like conveying mechanism, or the spaced-apart tines thereof, and controls the diverter in a correspondingly synchronous manner.", "The restraining arrangement at the abovementioned location for introducing transporting rollers into the conveying path preferably comprises a restraining pin for releasing a leading transporting roller and a further restraining pin for restraining trailing transporting rollers, it being possible for the restraining pins to be moved in the direction of their longitudinal axes between a restraining position in front of the respective transporting roller and a release position, in which they are disengaged from the respective transporting roller.", "The restraining pins can preferably be moved essentially perpendicularly to the transporting-roller running track of the downwardly sloping section.", "The invention further provides that the conveying path comprises at least one ejecting location or discharging line which branches off from it and has a downwardly sloping section, which has a fixed rolling ridge with a transporting-roller running track on its top side and on which the transporting roller(s) is or are conveyed to a collecting location by the action of gravitational force, the ejecting location comprising a diverter which can optionally be brought up to the conveying path in order to transfer the transporting roller(s) to the downwardly sloping section of the ejecting location, with the free end of the hook-like carrier element passing through the through-passage opening thereof, being disengaged in the process.", "BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS The invention is explained in more detail, by way of example, hereinbelow, with reference to the drawing, in which: FIG. 1 shows, schematically, an embodiment of an installation for transporting items of clothing hanging on clothes hangers with single-stage sorting, FIG. 2 shows, schematically, an embodiment of an installation for transporting items of clothing hanging on clothes hangers, with two-stage sorting, FIGS. 3 to 5 show an embodiment of the introduction location at which items of clothing hanging on clothes hangers are introduced into the conveying path of the installation of FIGS. 1 and 2, FIG. 3 showing a leading transporting roller being separated off from trailing transporting rollers, FIG. 4 showing the transfer of the transporting roller separated according to FIG. 3, and FIG. 5 showing the beginning of the next separating operation once the leading transporting roller has been transferred, FIG. 6 shows an ejecting location of the installation of FIGS. 1 and 2, at which transporting rollers with items of clothing hanging on clothes hangers are ejected from the conveying path, FIG. 7 shows a schematic perspective illustration of a transporting roller of the installation of FIGS. 1 and 2 on the conveying ridge of the conveying path of the installation, FIG. 8 shows a front view of the transporting roller from FIG. 7 in the direction transverse to the conveying path, and FIG. 9 shows a cross section through the transporting roller along line I—I from FIG. 7 without the carrier element, conveying path and barcoding, but with cutouts and a securing part.", "DETAILED DESCRIPTION OF THE INVENTION Since the conveying principle according to the invention of an installation for transporting objects is based on a specifically configured transporting roller with fixed side parts and a rotatable annular part in the center, this transporting roller, which is described in more detail, for example, in EP 1 013 569 A1, will be explained in more detail hereinbelow with reference to FIGS. 7, 8 and 9 , in which the same parts with the same functions have the same designations.", "In FIGS. 7 and 8, the transporting roller 1 essentially comprises two parallel disk-like outer flanges 2 , 3 on the end sides in each case, the elements referred to above as fixed side parts, and a central part 4 located therebetween, the element referred to above as a rotary annular part.", "Provided along the associated center axis 5 is a through-passage opening 6 , in which a securing part 7 is optionally located.", "The transporting roller 1 is connected, via its through-passage opening 6 , to an arcuate carrier element or hook 8 of a hanger, on which items of clothing are conveyed in the transporting installation in question.", "For this purpose, the central part 4 of the transporting roller 1 bears on a rolling ridge, which will be explained in more detail at a later stage in the text, of a conveying path of the transporting installation, the inclination of the same making it possible for the transporting roller 1 to move.", "As can be gathered from FIG. 8, the carrier element 8 , in the form of a clothes-hanger hook, bears on the ends of the securing-part 7 in each case.", "The securing part 7 is a hollow-cylindrical bushing, of which the end regions are bent outward in each case by riveting 24 , 25 .", "The inner construction of the transporting roller 1 cannot readily be seen from FIGS. 7 and 8.", "The transporting roller 1 is thus shown in section in FIG. 9 .", "The central part 4 , which is located between the first flange 3 and the second flange 2 , has an annular web 11 , which forms part of the first disk-like flange 3 , is directed towards the second flange 2 , is extended on one side and has a central bore as through-passage opening 6 of standard diameter.", "The annular web 11 has a slightly inclined outer surface from its point of attachment to the first flange 3 to its free end region 20 , which is flattened perpendicularly to the center axis 5 .", "The slightly inclined outer surface of the annular web 11 , at the same time, constitutes the inner running surface 12 for the rolling bodies 13 , 14 of a rolling-contact bearing.", "A multiplicity of rolling bodies are usually necessary for a reliably functioning rolling-contact bearing.", "The inner running surface 12 has, in the center, an encircling groove-like depression 18 , which is adapted in an accurately dimensioned manner to the outer surfaces of the rolling body 13 , 14 and in which the rolling bodies 13 , 14 can move.", "On the outside, the rotatable circumferential part 15 , in the form of an outer ring, encloses the rolling bodies 13 , 14 at a radial distance from the inner running surface 12 , and it has a disk-like side wall 21 which is angled perpendicularly to the center axis 5 and is located on the smaller-diameter side of the annular web 11 .", "In the direction of the side of the larger annular-web diameter or of the first flange 3 , the outer ring 15 is preferably open, inter alia for assembly reasons.", "The outer ring 15 is provided in each case with a slight amount of slot-induced play 16 , 17 in relation to the inner surfaces 23 , 22 of the first and of the second flanges 3 , 2 .", "On its paraxial inner running surface 10 , the outer ring 15 may likewise contain an encircling groove-like depression 19 , which is likewise adapted to the surfaces of the rolling body 13 , 14 .", "The second disk-like flange 2 is firmly secured against the free flattened end region 20 of the annular web 11 by the securing part 7 , the securing part 7 pressing the second flange 2 onto the end region 20 of the annular web 11 by rigid riveting 24 , 25 .", "The hollow-cylindrical securing part 7 has formed through it a channel 26 , into which the hook 8 of a clothes hanger is introduced and pushed through until that position of the hook 8 which is shown in FIG. 8 is reached.", "In the simplest case (FIGS.", "7 and 8 ), the second flange 2 may be provided with barcodings 37 .", "In FIG. 9, the second disk-like flange 2 has hole-like cutouts 27 , 28 in which, instead of the barcodings 37 shown in FIGS. 7 and 8, coding arrangements having electrical and electronic components (these arrangements not being shown) can be fastened.", "The coding arrangements may be, for example, radially or circularly arranged inductive, magnetic and/or capacitive arrangements or pins, made of a material differing from the flange material, in order for it to be possible to gather the storage information therefrom.", "The cutouts 27 , 28 , however, may also constitute an annular groove in which it is possible to secure electrical components, coupled with ROM and/or RAM memory modules, which have been introduced therein.", "As can be gathered from FIGS. 7 to 9 , in the transporting roller 1 , the central part 4 in other words has at least one peripheral annular circumferential part 15 which can be rotated separately from the two flanges 2 , 3 , the two flanges 2 , 3 being connected to one another and to the circumferential part 15 such that, in the case of the circumferential part 15 rotating as a result of bearing on the conveying path, the two flanges 2 , 3 are in a rest state irrespective of the rotation.", "This configuration of the transporting roller is the basis for the design according to the invention, which will be explained hereinbelow, of the transporting installation for transporting, in particular, items of clothing hanging on clothes hangers.", "In particular, this transporting roller, with fixed outer elements and a rotating inner element, allows a transporting means or a pushing arrangement to act directly on the transporting roller.", "A corresponding transporting installation will be explained hereinbelow with reference to FIGS. 1 to 6 .", "FIGS. 1 and 2 show, schematically, in general terms, two embodiments of the arrangement according to the invention for transporting, in particular, items of clothing hanging on clothes hangers, the installation according to FIG. 1 being provided for single-stage sorting, while the installation according to FIG. 2 is provided for two-stage sorting.", "The transporting installation shown in FIG. 1 comprises an open-circuit conveying path 41 with a supply location 42 at one end for unsorted goods and with an end 43 for the removal of sorted goods.", "Provided between the supply location 42 and the removal end 43 of the conveying path 41 are a plurality of parallel discharging lines, of which merely four discharging lines 44 to 47 are illustrated in FIG. 1 .", "The discharging lines 44 to 47 , on the inlet side, branch off from the conveying path 41 via diverters 48 to 51 .", "On the outlet side, the discharging lines 44 to 47 pass over into the conveying path 41 again via diverters 52 to 55 .", "Between their inlet and their outlet, the discharging lines 44 to 47 are each provided with a downwardly sloping section, in order to transfer the incoming goods to the outlet-side diverters 52 to 55 on account of the gravitational force thereof.", "The discharging lines provide a sorting means which is referred to here as being single-stage because the goods only pass through one or more of the discharging lines once.", "In contrast to this, FIG. 2 shows a modified design of the transporting installation of FIG. 1, with two-stage sorting of goods.", "In addition to the design with a plurality of discharging lines which is shown in FIG. 1, the transporting installation according to FIG. 2 comprises a return line 56 , which is connected to the conveying path 41 , via an inlet diverter 57 , downstream of the discharging lines 44 to 47 .", "In addition, the return line 56 is connected to the conveying path 41 upstream of the discharging lines 44 to 47 and downstream of the supply location 42 .", "For the purposes of transporting goods, the return line 46 likewise comprises a downwardly sloping section, which runs in the opposite direction to the downwardly sloping sections of the discharging lines 44 to 47 .", "Formed at the end of each discharging line 44 to 47 is a collecting location or a transfer station 58 , by means of which goods coming in via the discharging lines 44 to 47 are collected and can be introduced into the conveying path 41 again in a specific manner.", "A similar collecting location 62 is located at the end of the return line 56 .", "Details of the transporting installation according to FIGS. 1 and 2 can be gathered from FIGS. 3 to 5 , which show the installation in detail in the region of the supply location 42 .", "Accordingly, the conveying path 41 and the supply location 42 comprise a respective profile rail 63 , 64 with a generally C-shaped cross section.", "On account of the C-shaped cross section, the profile rail 63 , 64 is closed all the way round apart from a respective gap 65 , 66 , which is bounded by the mutually facing edges of the C-shaped profile rail.", "Of these two edges, the bottom or upwardly oriented edge is formed as a transporting-roller running track 67 , 68 .", "The running track 67 or 68 thus forms the top side of a respective rolling ridge 69 , 70 , which forms one of the mutually facing ends of the C-shaped profile rail 63 with the respective gap 65 , 66 located therebetween.", "The transporting roller 1 , which is shown in FIGS. 7 to 9 , FIGS. 3 to 5 showing four running-track rollers 1 , 1 ′, 1 ″ and 1 ′″, rides on said rolling ridge 69 , 70 , the central part 4 of each transporting roller being in rolling contact with the running track 67 , 68 , while the lateral, stationary flanges 2 , 3 of each transporting roller engage over the rolling ridge 69 , 70 on both sides, as a result of which the respective transporting roller is guided laterally.", "Additional lateral guidance for the transporting roller 1 is provided by the guide ridge 71 , 72 , which is located opposite the respective rolling ridge 69 , 70 , constitutes that end of the respective C-shaped profile 63 , 64 which is located opposite the rolling ridge 69 , 70 and engages between the two flanges 2 , 3 , albeit without coming into contact with the central part 4 of the transporting roller 1 .", "Interacting with one another, the rolling ridge 69 , 70 and the guide ridge 71 , 72 thus provide lateral positive guidance for the transporting roller 1 , with the result that said roller cannot pass laterally out of the profile rail 63 , 64 although, in the gap 65 , 66 of the latter, it can run in an essentially resistance-free manner, i.e. under rolling resistance, on the running track 67 , 68 .", "Added to this rolling resistance at most, when the goods hanging on the transporting rollers pivot laterally, is a brief contact resistance between the two flanges 2 , 3 and the ridges 69 to 72 .", "In order to convey the transporting rollers on the essentially horizontally running conveying path 41 or in the profile rail 63 , use is made of a link chain 73 , which is guided via gearwheels, spaced apart in the running direction, outside (as is shown) or alternatively within, the profile rail 63 and is driven via an electromotive drive (not shown).", "The motion of the link chain 73 is transmitted to the transporting rollers with the aid of a comb-like conveying mechanism 74 , which runs along the gap 65 in the profile rail 63 .", "The comb-like conveying mechanism is connected to the link chain 73 by a connecting means (not shown) which is arranged in the profile rail and, with the link chain 73 located on the outside, engages through a slot in the profile rail 63 (said slot not being shown either) located opposite the gap 65 .", "The tines of the comb-line conveying mechanism 74 run perpendicularly to the through-passage opening 6 of the transporting rollers running in the gap 65 and perpendicularly to the transporting-roller running track 68 .", "In the exemplary embodiment illustrated, the tines of the comb-like conveying mechanism are formed as uniformly spaced-apart carry-along pins for the free end of the hook-like carrier element 8 of the goods-securing part, e.g. in the form of a clothes hanger.", "The interspaces or clearances 78 of the tines or carry-along pins, of which two pins are designated 75 and 76 in FIGS. 3 to 5 , and the height of these spaces are selected such that the free end of the carrier element, coming from the supply location 42 , can pass into these spaces 78 and is then carried along together with the respective transporting roller and the goods hanging thereon.", "On account of the specific construction of the transporting roller, that flange 2 or 3 of the transporting roller which is oriented toward the interior of the profile rail engages with at least the two carry-along pins 75 , 76 defining the accommodating clearance, without relative movement, and the associated friction, occurring between these parts during the conveying movement, because these flanges are fixed and do not accompany the rolling movement of the rolling part of the transporting roller, as has been explained above with reference to FIGS. 7 to 9 .", "The operation of transporting rollers entering into the conveying path 41 via the supply location 42 will be explained hereinbelow with reference to FIGS. 3 to 4 .", "As has been indicated above, the supply location 42 is defined by a profile rail 64 with a C-shaped cross section corresponding to the profile rail 63 .", "At least in the region of the supply location 42 , that is to say at the location where the profile rail 64 opens out laterally into the profile rail 63 , the profile rail 64 has a downwardly sloping section, of which the lowermost point is situated at the location at which the profile rail 64 opens out into the profile rail 63 .", "On account of this downwardly sloping section, the transporting rollers, with the clothes hangers hanging on them, which are fed into the profile rail 64 at the other end of the latter move down the downwardly sloping section under the action of gravitational force.", "In order for the transporting rollers 1 to 1 ′″ to be fed into the conveying path 41 or the profile rail 63 separately and at the appropriate point in time, that is to say when a predetermined clearance 78 of the comb-like conveying mechanism 74 reaches the location at which the profile rail 64 opens out into the profile rail 63 , a restraining arrangement is formed at the supply location 42 upstream of the opening-out location.", "This restraining arrangement comprises two restraining pins 84 and 85 , which are spaced apart one behind the other in the longitudinal direction of the profile rail 64 .", "The restraining pins 84 and 85 can have their axial position adjusted in a manner known per se by means of drive cylinders 86 , 87 , with the aid of which the restraining pins 84 , 85 can optionally be displaced into a position in front of a respective transporting roller.", "In FIG. 3, the front restraining pin 84 , as seen in the conveying direction in the profile rail 64 , is located in front of the leading transporting roller 1 , with the result that the latter butts against the restraining pin 84 , while the rear restraining pin 85 is located on the rear side of said transporting roller 1 , in front of the next, trailing transporting roller 1 ′.", "The leading transporting roller 1 has thus already been separated off from the trailing transporting rollers 1 ′, 1 ″ and 1 ′″, of which the roller 1 ′ is restrained by the rear restraining pin 85 , while the following transporting rollers 1 ″, 1 ′″ butt against one another and against the transporting roller 1 ′.", "Starting from the position in FIG. 3, the next step is for the front restraining pin 84 then to be drawn back from its position in front of the transporting roller 1 when a restraining pin 82 a , which is concealed in FIG. 3, is situated immediately in front of the location at which the profile rail 64 opens out into the profile rail 63 .", "For this purpose, the motion of the link chain 73 is synchronized, in a manner which is not illustrated specifically, with the actuation of the drive cylinder 86 for the front restraining pin 84 , e.g. by means of a synchronization gearwheel 79 which interacts with the link chain 73 , with account being taken of the time which is required for the released transporting roller 1 to run out of its restrained position, with the restraining pin 84 extended, to the location at which the profile rail 64 opens out into the profile rail 63 .", "There, the free end of the hook-like carrier element 8 , which is oriented inward (toward the interior of the profile rail 63 .) and projects from the through-passage opening 6 of the transporting roller, engages in the clearance 78 of the conveying mechanism 74 , which is situated at the opening-out location, with the result that the transporting roller is carried along via the carrier element.", "The next step, as is shown in FIG. 5, is for a further transporting roller 1 ″″ to run up and thus form the last transporting roller of the abutting transporting rollers 1 ′, 1 ″, 1 ′″, 1 ″″, of which the now leading transporting roller 1 ′ comes into abutment against the restraining pin 84 , which has now been extended again, once the rear restraining pin 85 has been retracted.", "In order to separate the now leading transporting roller 1 ′, the rear restraining pin 85 is extended again, and the operation of separating the leading transporting roller, the beginning of which is shown in FIG. 3, begins anew, as has been explained above.", "A transporting-installation configuration which is similar to the supply location is located, for example, at the transition from the discharging lines 44 to 47 to the conveying path 41 .", "At this location, the diverters 52 to 55 , as appropriate, are formed in a manner corresponding to the profile rail 64 at the supply location 42 .", "FIG. 6 shows a location for moving the transporting rollers out of the conveying path 41 onto one of the discharging lines, for example the discharging line 44 according to FIGS. 1 and 2.", "The discharging line 44 , in turn, comprises a profile rail 88 , which is curved similarly to the profile rail 64 and opens out into the conveying path.", "The profile rail 88 likewise opens out into the profile rail 63 , which defines the conveying path 41 .", "The profile rail 88 , however, serves for ejecting transporting rollers, and the goods hanging on them, from the conveying path 41 .", "Since not every transporting roller is to be transferred from the profile rail 63 to the profile rail 88 , a diverter is formed between these two profile rails 63 and 88 .", "This diverter comprises a rolling-ridge section 89 , which is articulated pivotably on the profile rail 63 , and a guide-ridge section 90 , which is articulated pivotably on the profile rail 63 .", "In the pivoted-in state, the rolling-ridge section 89 forms part of the rolling ridge 69 of the profile rail 63 , while, in the pivoted-in state, the guide-ridge section 90 forms part of the guide ridge 71 of the profile rail 63 .", "In the pivoted-out state, or when the diverter is positioned such that transporting rollers are to be ejected from the profile rail 63 onto the profile rail 88 , the rolling-ridge section 89 interrupts the rolling ridge 69 and the guide-ridge section 90 interrupts the guide ridge 71 , and these sections 89 , 90 of the diverter, in the pivoted-out position, then adjoin a respective rolling ridge 91 and a guide ridge 92 of the profile rail 88 , as a result of which transporting rollers arriving at the diverter are ejected into the profile rail 88 .", "In order to adjust the sections 89 , 90 of the diverter, use is made of a diverter-switching mechanism 93 , which is merely illustrated schematically as a C-shaped clamp.", "As soon as a transporting roller located on the diverter leaves the diverter, it is transported by the downward slope on the discharging line, under the action of gravitational force, to a collecting location.", "LIST OF DESIGNATIONS 1 Transporting roller 2 Second flange 3 First flange 4 Central part 5 Center axis 6 Through-passage opening 7 Securing part 8 Carrier element 11 Annular web 12 Inner running surface 13 Rolling body 14 Rolling body 15 Circumferential part 16 Play 17 Play 18 First groove-like depression 19 Second groove-like depression 20 Free end region 21 Disk-like side wall 22 Inner surface 23 Inner surface 24 Riveting 25 Riveting 26 Channel 27 Cutout 28 Cutout 36 Latching cutout 37 Coding arrangement 41 Conveying path 42 Supply location 43 Removal end 44 Discharging line 45 Discharging line 46 Discharging line 47 Discharging line 48 Diverter 49 Diverter 50 Diverter 51 Diverter 52 Diverter 53 Diverter 54 Diverter 55 Diverter 56 Return line 57 Diverter 58 Collecting location 59 Collecting location 60 Collecting location 61 Collecting location 62 Collecting location 63 Profile rail 64 Profile rail 65 Gap 66 Gap 67 Running track 68 Running track 69 Rolling ridge 70 Rolling ridge 71 Guide ridge 72 Guide ridge 73 Link chain 74 Conveying mechanism 75 Carry-along pin 76 Carry-along pin 78 Clearance 79 Synchronization gearwheel 84 Restraining pin 85 Restraining pin 86 Drive cylinder 87 Drive cylinder 88 Profile rail 89 Rolling-ridge section 90 Guide-ridge section 91 Rolling ridge 92 Guide ridge 93 Diverter-switching mechanism" ]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor lasers having a greater degree of reliability and more particularly to structures that enable semiconductor lasers to be tested for reliability. The invention further relates to methods for testing the reliability of semiconductor lasers in wafer or chip form. The invention also relates to methods for the fabrication of semiconductor lasers which include the use of reliability tests in the fabrication process where the reliability tests include measuring the voltage drop or drops across one or more levels of a laser structure during the passage of current through the structure. Semiconductor lasers are used in a variety of applications that require a high level of reliability in the devices under normal use for specified periods of time. Reliability is of a special concern when the lasers are used in communications systems which are difficult to repair or replace, such as undersea cable. The cost of ensuring reliability of the semiconductor laser is a substantial part of the final cost of a laser transmitter or pump module. Thus, if the reliability of a laser is assured on the basis of tests performed on individual lasers after the full fabrication of the semiconductor laser devices or other incorporation of the devices in modules or packages, the cost of reliability assurance will be excessive due to the cost of handling and testing individual devices as well as the loss of materials and labor invested in the fabrication of those semiconductor laser devices which ultimately fail. The present invention overcomes these drawbacks. In optical semiconductor devices, excitation is introduced by electron (hole) injection to the conduction (valence) band through current biasing at the p-n junction. The voltage drop across a semiconductor junction (either a p-n junction or a Schottky Metal-Semiconductor junction) depends on the impurities present in the junction volume itself. Any impurity which tends to counteract the effect of the dopants or which provides current leakage paths will cause a deviation of the voltage across the junction from the value it would have in the absence of the impurity. Impurities which cause reliability problems tend to be those which diffuse rapidly and these impurities will cause the junction voltage to change with time when the material is stressed very hard by the passage of substantial current. In addition, morphological changes in either the metalsemiconductor interface or the p-n junctions of the semiconductor device under bias will also cause changes in the voltage which are accelerated by high currents. The theory of semiconductor laser reliability has been developed over many years since the invention of the semiconductor laser. For most lasers, the most important aspect of reliability is the change in efficiency of the laser. The problem of reliability of semiconductor lasers have been discussed in many articles, such as, for example, Aoyagi et al., “Threshold Current Density Dependence on p-doping in AlGaInP Laser,” SPIE Laser Diode Technology and Applications II, Vol. 1219 1990; Sakaki et al., “Doping Optimization in InGaAsP DH Lasers and Improved Characteristics in BH Lasers Grown by MOVPE,” Journal of Crystal Growth, Vol. 93 pp. 838-843, 1988; Zemel and Gallant, “Carrier Lifetime in InP/InGaAs/Inp by Open-Circuit Voltage and Photoluminescence Decay,” Journal of Applied Physics, Vol. 78 pg. 1094, 1995 and Ikegami et al., “Stress Test on 1.3 μm Buried-Heterostructure Laser Diode,” Electronics Letters, Vol. 19 pg. 382, 1983, which are herein incorporated by reference. While not wishing to be bound by theory, it is believed that changes in this performance indicator may be due to non-radiative recombination centers (NRRCs) in the active region. These NRRCs result in changes in light output at a constant current, an increase in the threshold current of the laser, or an increase in the current required to create a stated optical power at the output facet. Non-radiative recombination centers may be induced by a variety of original causes, including diffusion of impurities into the active layer from regions outside of the active layer during processing. Diffusion of these NRRCs may be assisted by electrical fields, currents or by the heat energy generated by current flow. Additionally, the NRRCs may be generated during manufacture by improper processing such as excess alloying of the metal contacts near the active region or by the incorporation of impurities such as copper which are known to act as NRRCs. In direct band-gap semiconductors, NRRCs occur mainly as a result of crystalline defects or impurities. Additionally, NRRCs occur due to spiking of metal through the layers of the laser. This spiking is known to cause laser degradation and failure. Since voltage can be measured very accurately, changes in voltage the junctions of the semiconductor device during the passage of current can be detected even when the change is very small. Thus, it is an object of the present invention to measure the changes in the voltage drop between the metal and the cap layer. The voltage drop between these layers correlates to changes in threshold current, which is a standard indicator of device reliability. Further, changes in voltage drops may be greatly accelerated by the passage of high currents through the device structure and these changes may be used to predict laser reliability. Because the present invention relies on principals of device physics which are well-known to those skilled in the art, it is possible to correlate the present invention tb the measurement of other voltage drops in the stack of layers making up the device, including the drop across the first heterojunction, the device p-n junction and the junctions between the laser layers and the blocking layer. The economic impact of the wafer level reliability testing of the present invention can be estimated by considering that much of the cost of a packaged laser is in the testing of the laser. Further, threats to laser reliability are often associated with errors in wafer fabrication which can be eliminated by the present invention. 2. Description of the Related Art The prior art includes descriptions of the causes of failure of reliability of semiconductor lasers and other semiconductor devices, and the use of wafer level testing as a part of the fabrication of integrated circuits, but no use of wafer level testing incorporating a voltage test point as part of the fabrication sequence of a laser and no description of laser structures incorporating voltage test points. In the past, it has been the practice to provide a test structure on the edge of a wafer or substrate to measure changes in the electrical properties. However, due to the high levels of electrical noise present in many manufacturing processes, it was usually necessary to halt the process and remove the wafer or substrate from the process in order to make the measurement. Therefore the process was interrupted and throughput was diminished. Further, the accuracy of the measurement was compromised by the need to re-start the process. Various methods for detecting defects in, and thus testing the future reliability of, thin film insulators in integrated circuits, particularly insulators in memory devices, such as EPROMs, EEPROMs, DRAMs, and other products with nonvolatile memory, have been discussed in the related arts. Unfortunately, existing wafer-level-reliability monitors of oxide breakdown voltage are not good predictors of laser reliability, and they are slow and destructive. Further, these methods have been limited to memory devices and not the semiconductor lasers of the present invention. One type of reliability testing for memory cells is called “burn-in”. In a burn-in test, the integrated circuit is subjected to elevated temperatures before performing functional tests on the integrated circuit. An integrated circuit undergoing a burn-in test is subjected to an elevated temperature for several hours. Because a large amount of time is required for a burn-in test, functional testing is usually performed before a burn-in test is performed. Later, burn-in tests and other tests for material defects are performed on samples in a group, or batch, of integrated circuits which have already undergone functional testing. Another prior method for determining defects in a semiconductor is to perform scanning electron microscope (“SEM”) views of the semiconductor surfaces. The SEM provides detailed information about the structure of the device, but requires the destructive slicing of the die to expose the cross sectional view. Additionally, a great deal of time is required to prepare and analyze the many SEM photographs needed to adequately represent an entire semiconductor. Another testing method for integrated circuits is shown by Gutt et al., U.S. Pat. No. 5,057,441. Gutt et al. disclose a method for testing metal films by measuring 1/f noise. They disclose causing a direct current and an alternating current to flow in the test portion, the combined currents being of sufficient magnitude to stimulate 1/f 2 noise in the test portion, determining the noise spectrum associated with the alternating current and comparing the slope and amplitude of the spectrum with predetermined values at one or more preselected frequencies. The present invention overcomes the drawbacks of the prior art and provides a method for efficiently testing semiconductor lasers at the wafer fabrication level. By testing the lasers at the wafer fabrication level, it is possible to greatly reduce the processing and testing costs inherent in laser fabrication. SUMMARY OF THE INVENTION The present invention tests laser structures in which voltage drops across specific interfaces, or a set of interfaces, may be tested while current flows through the laser in a normal manner. The invention further relates to a method for fabricating semiconductor lasers which incorporates testing the semiconductor lasers for reliability by testing the voltage drops across the semiconductor laser and using the results as predictors of reliability. Specifically, the invention relates to a method for manufacturing a semiconductor laser which includes the steps of providing one or more semiconductor substrates (here referred to as “wafers”) to be processed, and processing them. During the processing, a test point is formed on each of at least some of the substrates. The method further includes the step of evaluating a film test portion on at least one of the substrates relative to predetermined standards. If the result of the evaluation so indicates, the method further includes adjusting one or more process parameters such that subsequently processed substrates include film test portions conforming to the predetermined standards. The evaluating step comprises providing a voltage across the semiconductor laser through the voltage test point, determining the voltage drop across the semiconductor laser and comparing the voltage drop with a predetermined voltage profile. The method optionally includes performing one or more additional steps toward formation of the semiconductor laser to fabricate the laser for a particular application. The above and other advantages and features of the invention will be more clearly understood from the following detailed description which is provided in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a laser structure incorporating a test point attached to the cap layer of the laser. FIG. 2 shows a partially cut away side view of the structure of a typical laser during a step in the fabrication process having a voltage test point for evaluating reliability. FIG. 3 shows a partially cut away side view of a structure of a typical laser during a step in the fabrication process having a voltage test point for evaluating reliability according to a second aspect of the invention. FIG. 4 shows a partially cut away side view of a structure of a typical laser during a step in the fabrication process having a voltage test point for evaluating reliability according to a third aspect of the invention. FIG. 5 shows an exemplary circuit by which the voltage drop between the contact metal and the cap layer may be measured in order to develop reliability-predictive information. FIG. 6A shows current-voltage traces of a reliable laser during testing. FIG. 6B shows current-voltage traces of an unreliable laser during testing. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention will now be described with relation to a homojunction semiconductor laser. It is understood that the invention has broader applicability and may be used in any semiconductor laser, such as a single heterostructure laser, a double heterostructure laser, a multiple heterostructure laser, a homostructure laser or the like. Similarly, the process described below is but one method of many that could be used according to the present invention. The fundamental light producing mechanism in a semiconductor laser is the recombination of excess conduction band electrons and valence band holes. The semiconductor laser is formed of an active layer surrounded by two confinement layers. In a heterojunction semiconductor laser, one confinement layer is n doped and the other confinement layer is p doped. In the practice of the present invention, the active layer and the confinement layer may be comprised of any materials known to be used for semiconductor lasers. For example, the active layer may be, for example, AlGa, InAs, GaAs, InGaN, GaN, InGaAsP or any other materials which may form a semiconductor laser. The confinement layer may be formed, for example, of AlSb, GaSb, InP, AlGaAs, InGaAsP, InGaN, InGaAlN or the like. For example, the laser may include an active layer which includes GaAs that is sandwiched by two confinement layers having a lower index of refraction than the active layer, the upper confinement layer being p doped and the lower confinement layer being n doped. The present invention includes adding at least one voltage test point to the semiconductor laser during the wafer level fabrication of the semiconductor laser. Accordingly, a laser structure is disclosed which includes at least one voltage test point in addition to the contact points necessary for the normal operation of the laser, together with a method for testing the reliability of the semiconductor laser by which the voltage drop between two points in the laser structure is measured while a high current is passed through the structure. Further, a method for fabrication of semiconductor lasers is disclosed in which the fabrication sequence incorporates the testing of voltage drops in lasers as a means of assuring reliability. Reference is now made to the figures. FIG. 1 shows a top view of a semiconductor laser structure 10 which has incorporated thereon a voltage test point 20 . The voltage test point 20 is attached to a cap layer 30 of the semiconductor laser 10 . While the figure shows only a single test point, it should be understood that the semiconductor laser wafer may include a plurality of voltage test points. The semiconductor laser 10 further has an ohmic metal contact 40 which is connected to the cap layer 30 . The ohmic metal contact is formed on an upper portion of the cap layer 30 and covers at least part of the cap layer 30 . These contacts 20 , 40 are added to the semiconductor laser during the fabrication of the semiconductor laser 10 at the wafer level. The contacts are physically and electrically in contact with the semiconductor laser 10 and are formed of any suitable conductive metal. It should be understood that the voltage test point 20 may be fabricated onto the surface of the semiconductor laser 10 by any methods known in the art for wafer fabrication. Reference is now made to FIG. 2 . The figure shows a partially cut away side view of the structure of a typical semiconductor laser during fabrication having a voltage test point disposed thereon. The semiconductor laser 10 has an active region 50 displaced between an upper confinement region 80 and a lower confinement region 85 . The upper confinement region 80 is formed of an p doped material and the lower confinement region 85 is formed of a n doped material. The active region 50 , upper confinement region 80 and lower confinement region 85 are embedded in a blocking region 65 on a substrate 90 . The semiconductor laser 10 has an n-side contact 70 which is physically and electrically in contact with the substrate 90 . The semiconductor laser has a clad layer 60 displaced between the cap layer 30 and the blocking layer 65 and the upper confinement region 80 . The semiconductor laser has a cap layer 30 patterned over the clad layer 60 . The semiconductor laser 10 has a voltage test point 20 connected to a portion of the semiconductor laser 10 . The semiconductor laser 10 also includes an ohmic contact 40 in physical and electrical contact with an upper portion of the semiconductor laser 10 . The ohmic contact 40 and the voltage test point 20 are in electrical and physical contact with the semiconductor laser 10 through a cap layer 30 . Reference is now made to FIG. 3 . The figure shows a partially cut away side view of a structure of a typical semiconductor laser during fabrication having a voltage test point 220 disposed on a clad layer 260 according to a second aspect of the invention. The semiconductor laser 210 has an active region 250 displaced between an upper confinement region 280 and a lower confinement region 285 . The upper confinement region 280 is formed of an p doped material and the lower confinement region 285 is formed of a n doped material. The active region 250 , upper confinement region 280 and lower confinement region 285 are embedded in a blocking region 265 on a substrate 290 . The semiconductor laser 210 has an n-side contact 270 which is physically and electrically in contact with the substrate 290 . The semiconductor laser has a clad layer 260 displaced between the cap layer 230 and the blocking layer 265 and the upper confinement region 280 . The semiconductor laser has a cap layer 230 patterned over the clad layer 260 . The semiconductor laser 210 has a voltage test point 220 connected to the upper portion of the clad layer 260 . The semiconductor laser 210 also includes an ohmic contact 240 in physical and electrical contact with an upper portion of the semiconductor laser 210 . The semiconductor laser 210 is then selectively cut away by one or more etching processes to remove a portion of the cap layer 220 to expose the clad layer 260 . FIG. 3 shows that the clad layer 260 is also selectively etched to expose the clad layer 260 and permit placement of test point 220 at a location between upper and lower planar surfaces of clad layer 260 ; however, it is possible to only remove the cap layer 230 so as to expose the clad layer 260 . The voltage test point 220 is then formed over the planar upper surface portion of the clad layer 260 so that the voltage loss between the metal layer 240 and the clad layer 260 can be measured as discussed below. Reference is now made to FIG. 4 . The figure shows a partially cut away side view of a structure of a typical semiconductor laser during fabrication having a voltage test point 320 disposed on a blocking layer 365 according to a third aspect of the invention. The semiconductor laser 310 has an active region 350 displaced between an upper confinement region 380 and a lower confinement region 385 . The upper confinement region 380 is formed of an p doped material and the lower confinement region 385 is formed of a n doped material. The active region 350 , upper confinement region 380 and lower confinement region 385 are embedded in a blocking region 365 on a substrate 390 . The semiconductor laser 310 has an n-side contact 370 which is physically and electrically in contact with the substrate 390 . The semiconductor laser has a clad layer 360 displaced between the cap layer 330 and the blocking layer 365 and the upper confinement region 380 . The semiconductor laser has a cap layer 330 patterned over the clad layer 360 . The semiconductor laser 310 has a voltage test point 320 connected to an upper portion of the blocking layer 365 . The semiconductor laser 310 also includes an ohmic contact 340 in physical and electrical contact with an upper portion of the semiconductor laser 310 . The semiconductor laser 310 is then selectively cut away by one or more etching processes to remove a portion of the cap layer 320 and a portion of the clad layer 360 to expose the blocking layer 360 . FIG. 4 shows that the blocking layer 365 is also selectively etched to a desired depth to expose the blocking layer 365 ; however, it is possible to only remove a portion of the cap layer 330 and a portion of the clad layer 360 so as to expose the blocking layer 365 . The voltage test point 320 is then formed over a portion of the blocking layer 365 so that the voltage loss between the metal layer 340 and the blocking layer 365 can be measured as discussed below. Reference is now made to FIG. 5 . This figure shows an exemplary circuit by which the voltage drop in the semiconductor laser between the contact metal 40 and the cap layer 30 may be measured in order to develop reliability-predictive information. The circuit 100 includes a current source 120 which provides current across the semiconductor laser 10 . The current across the semiconductor laser according to the present invention is that current used to operate semiconductor lasers in general. The selection of the current level will vary depending upon the type of semiconductor laser and materials that the semiconductor laser is formed from. Generally, the test current may range from between about 0.1 milliamp to about 1 amp. Preferably the current density equals or exceeds 1×10 7 amps/meter 2 . The current I flows to the ohmic contact 40 which is located on the cap layer 30 of the semiconductor laser 10 . Voltage drop, Vc, between the metal 40 and the cap layer 30 is between node 130 and node 140 . The current I flows from the current source 120 to the ohmic contact 40 and into the active layer 50 and the substrate 90 . The current I flows through the substrate 90 and out the n-side contact 70 . A separate contact, voltage test point 20 , is provided on the cap layer 30 . The voltage drop Vc between the metal 40 and the cap layer 30 can be monitored by a voltage measurement device 110 directly across the terminals 40 , 20 of the semiconductor laser 10 . The voltage measurement device 100 may include any well known voltage measuring device such as so-called multi-meters, oscilloscopes or other devices. The voltage drop Vc between the ohmic contact metal 40 and the cap layer 30 (V 2−V 1 ) correlates to the changes in threshold current which is the standard indicator of semiconductor device reliability. Since voltage can be measured very accurately, changes in voltage across the junctions of the semiconductor device during the passage of current can be detected even when the change is very small. The smaller the voltage drop, the more reliable the semiconductor laser will be. The fact that the testing procedure takes place during the fabrication of the semiconductor laser allows for a determination of which semiconductor lasers have impurities in the NRRCs and should be discarded before further processing. Additionally, in situ testing of the semiconductor lasers during fabrication allows for modifications to the fabrication process if it is found that the impurities are due to a specific processing flaw. Further, the present invention can be used to measure the change in voltage drop acceleration by increasing the current I from the current source 120 . Reference is now made to FIG. 6 . FIG. 6A shows current-voltage traces of a reliable laser during testing while FIG. 6B shows current-voltage traces of an unreliable laser during testing. Voltage is measured on the vertical axis and current is measured on the horizontal axis. As can be seen from FIG. 6A, as the current increases, the voltage drop between the ohmic contact 40 and the cap layer 30 increases. However, the ratio of the voltage drop Vc to the current is close to a linear relationship. The voltage/current profile in FIG. 6A indicates that the semiconductor laser was successfully fabricated as the resistance of the contact increases only slightly and the semiconductor laser should have good reliability during its use. FIG. 6B on the other hand, shows the results of a semiconductor laser which is unreliable. As can be seen from the figure, as the current increases, the voltage increases dramatically. The voltage/current profile of this test indicates that the resistance between the metal and the cap layer increases as the current is increased due to impurities during fabrication and that the laser is likely to fail during use. Thus, the present invention provides a method and apparatus for testing semiconductor lasers for defects at the wafer or chip level during fabrication. It should again be noted that although the invention has been described with specific reference to homojunction semiconductor lasers, the invention has broader applicability and may be used in any semiconductor laser, such as a single heterostructure laser, a double heterostructure laser, or the like. Additionally, the semiconductor laser may also be coupled by a waveguide in an optoelectronic integrated circuit to additional circuitry, such as, for example additional lasers, photodetectors, modulators, semiconductor amplifiers, splitters, beam expanders or the like. Similarly, the process described above is but one method of many that could be used. Accordingly, the above description and accompanying drawings are only illustrative of preferred embodiments which can achieve the features and advantages of the present invention. It is not intended that the invention be limited to the embodiments shown and described in detail herein. The invention is only limited by the scope of the following claims.
The invention relates to semiconductor lasers and more particularly to structures which enable the semiconductor lasers to be tested for reliability. The invention further relates to methods for testing the reliability of semiconductor lasers in wafer or chip form. The invention also relates to methods for the fabrication of semiconductor lasers which includes the use of reliability tests in the fabrication process where the reliability tests includes measuring the voltage drop or drops across one or more levels of a laser structure during the passage of current through the structure.
Briefly summarize the main idea's components and working principles as described in the context.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention The present invention relates to semiconductor lasers having a greater degree of reliability and more particularly to structures that enable semiconductor lasers to be tested for reliability.", "The invention further relates to methods for testing the reliability of semiconductor lasers in wafer or chip form.", "The invention also relates to methods for the fabrication of semiconductor lasers which include the use of reliability tests in the fabrication process where the reliability tests include measuring the voltage drop or drops across one or more levels of a laser structure during the passage of current through the structure.", "Semiconductor lasers are used in a variety of applications that require a high level of reliability in the devices under normal use for specified periods of time.", "Reliability is of a special concern when the lasers are used in communications systems which are difficult to repair or replace, such as undersea cable.", "The cost of ensuring reliability of the semiconductor laser is a substantial part of the final cost of a laser transmitter or pump module.", "Thus, if the reliability of a laser is assured on the basis of tests performed on individual lasers after the full fabrication of the semiconductor laser devices or other incorporation of the devices in modules or packages, the cost of reliability assurance will be excessive due to the cost of handling and testing individual devices as well as the loss of materials and labor invested in the fabrication of those semiconductor laser devices which ultimately fail.", "The present invention overcomes these drawbacks.", "In optical semiconductor devices, excitation is introduced by electron (hole) injection to the conduction (valence) band through current biasing at the p-n junction.", "The voltage drop across a semiconductor junction (either a p-n junction or a Schottky Metal-Semiconductor junction) depends on the impurities present in the junction volume itself.", "Any impurity which tends to counteract the effect of the dopants or which provides current leakage paths will cause a deviation of the voltage across the junction from the value it would have in the absence of the impurity.", "Impurities which cause reliability problems tend to be those which diffuse rapidly and these impurities will cause the junction voltage to change with time when the material is stressed very hard by the passage of substantial current.", "In addition, morphological changes in either the metalsemiconductor interface or the p-n junctions of the semiconductor device under bias will also cause changes in the voltage which are accelerated by high currents.", "The theory of semiconductor laser reliability has been developed over many years since the invention of the semiconductor laser.", "For most lasers, the most important aspect of reliability is the change in efficiency of the laser.", "The problem of reliability of semiconductor lasers have been discussed in many articles, such as, for example, Aoyagi et al.", ", “Threshold Current Density Dependence on p-doping in AlGaInP Laser,” SPIE Laser Diode Technology and Applications II, Vol. 1219 1990;", "Sakaki et al.", ", “Doping Optimization in InGaAsP DH Lasers and Improved Characteristics in BH Lasers Grown by MOVPE,” Journal of Crystal Growth, Vol. 93 pp. 838-843, 1988;", "Zemel and Gallant, “Carrier Lifetime in InP/InGaAs/Inp by Open-Circuit Voltage and Photoluminescence Decay,” Journal of Applied Physics, Vol. 78 pg.", "1094, 1995 and Ikegami et al.", ", “Stress Test on 1.3 μm Buried-Heterostructure Laser Diode,” Electronics Letters, Vol. 19 pg.", "382, 1983, which are herein incorporated by reference.", "While not wishing to be bound by theory, it is believed that changes in this performance indicator may be due to non-radiative recombination centers (NRRCs) in the active region.", "These NRRCs result in changes in light output at a constant current, an increase in the threshold current of the laser, or an increase in the current required to create a stated optical power at the output facet.", "Non-radiative recombination centers may be induced by a variety of original causes, including diffusion of impurities into the active layer from regions outside of the active layer during processing.", "Diffusion of these NRRCs may be assisted by electrical fields, currents or by the heat energy generated by current flow.", "Additionally, the NRRCs may be generated during manufacture by improper processing such as excess alloying of the metal contacts near the active region or by the incorporation of impurities such as copper which are known to act as NRRCs.", "In direct band-gap semiconductors, NRRCs occur mainly as a result of crystalline defects or impurities.", "Additionally, NRRCs occur due to spiking of metal through the layers of the laser.", "This spiking is known to cause laser degradation and failure.", "Since voltage can be measured very accurately, changes in voltage the junctions of the semiconductor device during the passage of current can be detected even when the change is very small.", "Thus, it is an object of the present invention to measure the changes in the voltage drop between the metal and the cap layer.", "The voltage drop between these layers correlates to changes in threshold current, which is a standard indicator of device reliability.", "Further, changes in voltage drops may be greatly accelerated by the passage of high currents through the device structure and these changes may be used to predict laser reliability.", "Because the present invention relies on principals of device physics which are well-known to those skilled in the art, it is possible to correlate the present invention tb the measurement of other voltage drops in the stack of layers making up the device, including the drop across the first heterojunction, the device p-n junction and the junctions between the laser layers and the blocking layer.", "The economic impact of the wafer level reliability testing of the present invention can be estimated by considering that much of the cost of a packaged laser is in the testing of the laser.", "Further, threats to laser reliability are often associated with errors in wafer fabrication which can be eliminated by the present invention.", "Description of the Related Art The prior art includes descriptions of the causes of failure of reliability of semiconductor lasers and other semiconductor devices, and the use of wafer level testing as a part of the fabrication of integrated circuits, but no use of wafer level testing incorporating a voltage test point as part of the fabrication sequence of a laser and no description of laser structures incorporating voltage test points.", "In the past, it has been the practice to provide a test structure on the edge of a wafer or substrate to measure changes in the electrical properties.", "However, due to the high levels of electrical noise present in many manufacturing processes, it was usually necessary to halt the process and remove the wafer or substrate from the process in order to make the measurement.", "Therefore the process was interrupted and throughput was diminished.", "Further, the accuracy of the measurement was compromised by the need to re-start the process.", "Various methods for detecting defects in, and thus testing the future reliability of, thin film insulators in integrated circuits, particularly insulators in memory devices, such as EPROMs, EEPROMs, DRAMs, and other products with nonvolatile memory, have been discussed in the related arts.", "Unfortunately, existing wafer-level-reliability monitors of oxide breakdown voltage are not good predictors of laser reliability, and they are slow and destructive.", "Further, these methods have been limited to memory devices and not the semiconductor lasers of the present invention.", "One type of reliability testing for memory cells is called “burn-in.”", "In a burn-in test, the integrated circuit is subjected to elevated temperatures before performing functional tests on the integrated circuit.", "An integrated circuit undergoing a burn-in test is subjected to an elevated temperature for several hours.", "Because a large amount of time is required for a burn-in test, functional testing is usually performed before a burn-in test is performed.", "Later, burn-in tests and other tests for material defects are performed on samples in a group, or batch, of integrated circuits which have already undergone functional testing.", "Another prior method for determining defects in a semiconductor is to perform scanning electron microscope (“SEM”) views of the semiconductor surfaces.", "The SEM provides detailed information about the structure of the device, but requires the destructive slicing of the die to expose the cross sectional view.", "Additionally, a great deal of time is required to prepare and analyze the many SEM photographs needed to adequately represent an entire semiconductor.", "Another testing method for integrated circuits is shown by Gutt et al.", ", U.S. Pat. No. 5,057,441.", "Gutt et al.", "disclose a method for testing metal films by measuring 1/f noise.", "They disclose causing a direct current and an alternating current to flow in the test portion, the combined currents being of sufficient magnitude to stimulate 1/f 2 noise in the test portion, determining the noise spectrum associated with the alternating current and comparing the slope and amplitude of the spectrum with predetermined values at one or more preselected frequencies.", "The present invention overcomes the drawbacks of the prior art and provides a method for efficiently testing semiconductor lasers at the wafer fabrication level.", "By testing the lasers at the wafer fabrication level, it is possible to greatly reduce the processing and testing costs inherent in laser fabrication.", "SUMMARY OF THE INVENTION The present invention tests laser structures in which voltage drops across specific interfaces, or a set of interfaces, may be tested while current flows through the laser in a normal manner.", "The invention further relates to a method for fabricating semiconductor lasers which incorporates testing the semiconductor lasers for reliability by testing the voltage drops across the semiconductor laser and using the results as predictors of reliability.", "Specifically, the invention relates to a method for manufacturing a semiconductor laser which includes the steps of providing one or more semiconductor substrates (here referred to as “wafers”) to be processed, and processing them.", "During the processing, a test point is formed on each of at least some of the substrates.", "The method further includes the step of evaluating a film test portion on at least one of the substrates relative to predetermined standards.", "If the result of the evaluation so indicates, the method further includes adjusting one or more process parameters such that subsequently processed substrates include film test portions conforming to the predetermined standards.", "The evaluating step comprises providing a voltage across the semiconductor laser through the voltage test point, determining the voltage drop across the semiconductor laser and comparing the voltage drop with a predetermined voltage profile.", "The method optionally includes performing one or more additional steps toward formation of the semiconductor laser to fabricate the laser for a particular application.", "The above and other advantages and features of the invention will be more clearly understood from the following detailed description which is provided in connection with the accompanying drawings.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a laser structure incorporating a test point attached to the cap layer of the laser.", "FIG. 2 shows a partially cut away side view of the structure of a typical laser during a step in the fabrication process having a voltage test point for evaluating reliability.", "FIG. 3 shows a partially cut away side view of a structure of a typical laser during a step in the fabrication process having a voltage test point for evaluating reliability according to a second aspect of the invention.", "FIG. 4 shows a partially cut away side view of a structure of a typical laser during a step in the fabrication process having a voltage test point for evaluating reliability according to a third aspect of the invention.", "FIG. 5 shows an exemplary circuit by which the voltage drop between the contact metal and the cap layer may be measured in order to develop reliability-predictive information.", "FIG. 6A shows current-voltage traces of a reliable laser during testing.", "FIG. 6B shows current-voltage traces of an unreliable laser during testing.", "DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention will now be described with relation to a homojunction semiconductor laser.", "It is understood that the invention has broader applicability and may be used in any semiconductor laser, such as a single heterostructure laser, a double heterostructure laser, a multiple heterostructure laser, a homostructure laser or the like.", "Similarly, the process described below is but one method of many that could be used according to the present invention.", "The fundamental light producing mechanism in a semiconductor laser is the recombination of excess conduction band electrons and valence band holes.", "The semiconductor laser is formed of an active layer surrounded by two confinement layers.", "In a heterojunction semiconductor laser, one confinement layer is n doped and the other confinement layer is p doped.", "In the practice of the present invention, the active layer and the confinement layer may be comprised of any materials known to be used for semiconductor lasers.", "For example, the active layer may be, for example, AlGa, InAs, GaAs, InGaN, GaN, InGaAsP or any other materials which may form a semiconductor laser.", "The confinement layer may be formed, for example, of AlSb, GaSb, InP, AlGaAs, InGaAsP, InGaN, InGaAlN or the like.", "For example, the laser may include an active layer which includes GaAs that is sandwiched by two confinement layers having a lower index of refraction than the active layer, the upper confinement layer being p doped and the lower confinement layer being n doped.", "The present invention includes adding at least one voltage test point to the semiconductor laser during the wafer level fabrication of the semiconductor laser.", "Accordingly, a laser structure is disclosed which includes at least one voltage test point in addition to the contact points necessary for the normal operation of the laser, together with a method for testing the reliability of the semiconductor laser by which the voltage drop between two points in the laser structure is measured while a high current is passed through the structure.", "Further, a method for fabrication of semiconductor lasers is disclosed in which the fabrication sequence incorporates the testing of voltage drops in lasers as a means of assuring reliability.", "Reference is now made to the figures.", "FIG. 1 shows a top view of a semiconductor laser structure 10 which has incorporated thereon a voltage test point 20 .", "The voltage test point 20 is attached to a cap layer 30 of the semiconductor laser 10 .", "While the figure shows only a single test point, it should be understood that the semiconductor laser wafer may include a plurality of voltage test points.", "The semiconductor laser 10 further has an ohmic metal contact 40 which is connected to the cap layer 30 .", "The ohmic metal contact is formed on an upper portion of the cap layer 30 and covers at least part of the cap layer 30 .", "These contacts 20 , 40 are added to the semiconductor laser during the fabrication of the semiconductor laser 10 at the wafer level.", "The contacts are physically and electrically in contact with the semiconductor laser 10 and are formed of any suitable conductive metal.", "It should be understood that the voltage test point 20 may be fabricated onto the surface of the semiconductor laser 10 by any methods known in the art for wafer fabrication.", "Reference is now made to FIG. 2 .", "The figure shows a partially cut away side view of the structure of a typical semiconductor laser during fabrication having a voltage test point disposed thereon.", "The semiconductor laser 10 has an active region 50 displaced between an upper confinement region 80 and a lower confinement region 85 .", "The upper confinement region 80 is formed of an p doped material and the lower confinement region 85 is formed of a n doped material.", "The active region 50 , upper confinement region 80 and lower confinement region 85 are embedded in a blocking region 65 on a substrate 90 .", "The semiconductor laser 10 has an n-side contact 70 which is physically and electrically in contact with the substrate 90 .", "The semiconductor laser has a clad layer 60 displaced between the cap layer 30 and the blocking layer 65 and the upper confinement region 80 .", "The semiconductor laser has a cap layer 30 patterned over the clad layer 60 .", "The semiconductor laser 10 has a voltage test point 20 connected to a portion of the semiconductor laser 10 .", "The semiconductor laser 10 also includes an ohmic contact 40 in physical and electrical contact with an upper portion of the semiconductor laser 10 .", "The ohmic contact 40 and the voltage test point 20 are in electrical and physical contact with the semiconductor laser 10 through a cap layer 30 .", "Reference is now made to FIG. 3 .", "The figure shows a partially cut away side view of a structure of a typical semiconductor laser during fabrication having a voltage test point 220 disposed on a clad layer 260 according to a second aspect of the invention.", "The semiconductor laser 210 has an active region 250 displaced between an upper confinement region 280 and a lower confinement region 285 .", "The upper confinement region 280 is formed of an p doped material and the lower confinement region 285 is formed of a n doped material.", "The active region 250 , upper confinement region 280 and lower confinement region 285 are embedded in a blocking region 265 on a substrate 290 .", "The semiconductor laser 210 has an n-side contact 270 which is physically and electrically in contact with the substrate 290 .", "The semiconductor laser has a clad layer 260 displaced between the cap layer 230 and the blocking layer 265 and the upper confinement region 280 .", "The semiconductor laser has a cap layer 230 patterned over the clad layer 260 .", "The semiconductor laser 210 has a voltage test point 220 connected to the upper portion of the clad layer 260 .", "The semiconductor laser 210 also includes an ohmic contact 240 in physical and electrical contact with an upper portion of the semiconductor laser 210 .", "The semiconductor laser 210 is then selectively cut away by one or more etching processes to remove a portion of the cap layer 220 to expose the clad layer 260 .", "FIG. 3 shows that the clad layer 260 is also selectively etched to expose the clad layer 260 and permit placement of test point 220 at a location between upper and lower planar surfaces of clad layer 260 ;", "however, it is possible to only remove the cap layer 230 so as to expose the clad layer 260 .", "The voltage test point 220 is then formed over the planar upper surface portion of the clad layer 260 so that the voltage loss between the metal layer 240 and the clad layer 260 can be measured as discussed below.", "Reference is now made to FIG. 4 .", "The figure shows a partially cut away side view of a structure of a typical semiconductor laser during fabrication having a voltage test point 320 disposed on a blocking layer 365 according to a third aspect of the invention.", "The semiconductor laser 310 has an active region 350 displaced between an upper confinement region 380 and a lower confinement region 385 .", "The upper confinement region 380 is formed of an p doped material and the lower confinement region 385 is formed of a n doped material.", "The active region 350 , upper confinement region 380 and lower confinement region 385 are embedded in a blocking region 365 on a substrate 390 .", "The semiconductor laser 310 has an n-side contact 370 which is physically and electrically in contact with the substrate 390 .", "The semiconductor laser has a clad layer 360 displaced between the cap layer 330 and the blocking layer 365 and the upper confinement region 380 .", "The semiconductor laser has a cap layer 330 patterned over the clad layer 360 .", "The semiconductor laser 310 has a voltage test point 320 connected to an upper portion of the blocking layer 365 .", "The semiconductor laser 310 also includes an ohmic contact 340 in physical and electrical contact with an upper portion of the semiconductor laser 310 .", "The semiconductor laser 310 is then selectively cut away by one or more etching processes to remove a portion of the cap layer 320 and a portion of the clad layer 360 to expose the blocking layer 360 .", "FIG. 4 shows that the blocking layer 365 is also selectively etched to a desired depth to expose the blocking layer 365 ;", "however, it is possible to only remove a portion of the cap layer 330 and a portion of the clad layer 360 so as to expose the blocking layer 365 .", "The voltage test point 320 is then formed over a portion of the blocking layer 365 so that the voltage loss between the metal layer 340 and the blocking layer 365 can be measured as discussed below.", "Reference is now made to FIG. 5 .", "This figure shows an exemplary circuit by which the voltage drop in the semiconductor laser between the contact metal 40 and the cap layer 30 may be measured in order to develop reliability-predictive information.", "The circuit 100 includes a current source 120 which provides current across the semiconductor laser 10 .", "The current across the semiconductor laser according to the present invention is that current used to operate semiconductor lasers in general.", "The selection of the current level will vary depending upon the type of semiconductor laser and materials that the semiconductor laser is formed from.", "Generally, the test current may range from between about 0.1 milliamp to about 1 amp.", "Preferably the current density equals or exceeds 1×10 7 amps/meter 2 .", "The current I flows to the ohmic contact 40 which is located on the cap layer 30 of the semiconductor laser 10 .", "Voltage drop, Vc, between the metal 40 and the cap layer 30 is between node 130 and node 140 .", "The current I flows from the current source 120 to the ohmic contact 40 and into the active layer 50 and the substrate 90 .", "The current I flows through the substrate 90 and out the n-side contact 70 .", "A separate contact, voltage test point 20 , is provided on the cap layer 30 .", "The voltage drop Vc between the metal 40 and the cap layer 30 can be monitored by a voltage measurement device 110 directly across the terminals 40 , 20 of the semiconductor laser 10 .", "The voltage measurement device 100 may include any well known voltage measuring device such as so-called multi-meters, oscilloscopes or other devices.", "The voltage drop Vc between the ohmic contact metal 40 and the cap layer 30 (V 2−V 1 ) correlates to the changes in threshold current which is the standard indicator of semiconductor device reliability.", "Since voltage can be measured very accurately, changes in voltage across the junctions of the semiconductor device during the passage of current can be detected even when the change is very small.", "The smaller the voltage drop, the more reliable the semiconductor laser will be.", "The fact that the testing procedure takes place during the fabrication of the semiconductor laser allows for a determination of which semiconductor lasers have impurities in the NRRCs and should be discarded before further processing.", "Additionally, in situ testing of the semiconductor lasers during fabrication allows for modifications to the fabrication process if it is found that the impurities are due to a specific processing flaw.", "Further, the present invention can be used to measure the change in voltage drop acceleration by increasing the current I from the current source 120 .", "Reference is now made to FIG. 6 .", "FIG. 6A shows current-voltage traces of a reliable laser during testing while FIG. 6B shows current-voltage traces of an unreliable laser during testing.", "Voltage is measured on the vertical axis and current is measured on the horizontal axis.", "As can be seen from FIG. 6A, as the current increases, the voltage drop between the ohmic contact 40 and the cap layer 30 increases.", "However, the ratio of the voltage drop Vc to the current is close to a linear relationship.", "The voltage/current profile in FIG. 6A indicates that the semiconductor laser was successfully fabricated as the resistance of the contact increases only slightly and the semiconductor laser should have good reliability during its use.", "FIG. 6B on the other hand, shows the results of a semiconductor laser which is unreliable.", "As can be seen from the figure, as the current increases, the voltage increases dramatically.", "The voltage/current profile of this test indicates that the resistance between the metal and the cap layer increases as the current is increased due to impurities during fabrication and that the laser is likely to fail during use.", "Thus, the present invention provides a method and apparatus for testing semiconductor lasers for defects at the wafer or chip level during fabrication.", "It should again be noted that although the invention has been described with specific reference to homojunction semiconductor lasers, the invention has broader applicability and may be used in any semiconductor laser, such as a single heterostructure laser, a double heterostructure laser, or the like.", "Additionally, the semiconductor laser may also be coupled by a waveguide in an optoelectronic integrated circuit to additional circuitry, such as, for example additional lasers, photodetectors, modulators, semiconductor amplifiers, splitters, beam expanders or the like.", "Similarly, the process described above is but one method of many that could be used.", "Accordingly, the above description and accompanying drawings are only illustrative of preferred embodiments which can achieve the features and advantages of the present invention.", "It is not intended that the invention be limited to the embodiments shown and described in detail herein.", "The invention is only limited by the scope of the following claims." ]
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a device for determining the levelness of compound strings or string sets, namely bichords and trichords, of a grand piano. The device uses the upper surface of the key bed of the piano as a reference surface and determines levelness of the aforesaid string sets. In addition to the string leveling device, a method of use thereof is provided. 2. Description of the Prior Art The history of the modern piano begins with the pianoforte developed by a harpsichord builder, Bartolommeo Christofori. Christofori invented the instrument in Florence in 1709 and completed a prototype around 1720. The main driving force behind the instrument's development was that, in contradistinction to the predecessor instruments—the harpsichord and the clavichord—the piano provided variations in volume. Additionally development was spurred on by the desire to play fuller, less delicate music. Musicians of the time sought a full rich sound and were unsatisfied by the strong and uniform harpsichord tone produced by plucking large strings with keyboard-controlled quills. On the other hand, the percussive action of the clavichord, while allowing for variations in volume, produced weak tones by striking brass hammers against small, thin strings. Of the several versions of the piano invented in the Eighteenth century, Christofori's pianoforte, is most closely related to the modern-day grand piano in that the hammers thereof are wooden blocks covered on the striking surface with soft leather. Later in the Eighteenth century a piano hammer was designed with the same basic shape that survives today. In this design, two layers of leather were used with the inner layer being a firm leather, and the outer layer being softer. The final form of the leather covered piano hammer used three layers of leather of varying firmness with the softest leather on the outside and the firmest layer on the inside. This provided a piano hammer that was soft and compliant at the surface to provide the requisite tone for pianissimo playing and a hammer firmer underneath to provide the strength for forte playing. As the grand piano developed, it became more and more a solo instrument, and needed to be louder. To increase volume, strings needed to be thicker and the support structure stronger, so that greater tension could be achieved. The frame of the pianos, commonly made of wood, became thicker and heavier, and was strengthened by cross-bracing. By 1820, English manufacturer John Broadwood began to build iron hitch pin plates, which now meant plates were made of more metal than wood. In 1825 Alpheus Babcock patented the cast-iron frame and further in 1843, American manufacturer Jonas Chickering began making pianos with the full-perimeter plate—a feature of modern grand pianos. In 1821 a French builder, Sebastian Erard, invented the last major basic refinement of the piano action; the double escapement. Shortly thereafter, the heavy iron frame required by the action and the higher tensioned strings was provided, and then cross-stringing, a system whereby the long bass strings cross over the shorter middle-range strings, was invented. After the invention of the iron frame for the strings on a piano, heavier strings, including bichords and trichords, could be used at higher tensions to produce a fuller sound from the piano. This rendered the leather covered piano hammer unacceptable. The result was the development and patenting of a felt covered piano hammer by Alpheus Babcock in 1833. These hammers provided a more acceptable tone than the leather covered hammers. In the late Nineteenth century machines were invented to cover the raw wood piano hammers with felt. The felt hammers enabled the manufacturer to fine tune the tone of the piano by adjusting the hardness of the felt. The process of tonally regulating the piano hammers is called voicing, requires skilled piano technicians, and is a time consuming operation. Initially, the piano hammer felt is checked for proper shaping, particularly that the striking surface is flat across the width thereof. During voicing, the technician adjusts the tone of a hammer by adjusting the softness or the hardness of the hammer felt. When a tone sounds too soft, by applying a solution of lacquer and lacquer thinner to the hammer felt the technician adjusts the felt hardness and the tone produced at that site. Alternate methods of adjusting hammer felt hardness include working the hammer felt with a needle to loosen the fibrous structure thereof. String leveling of a grand piano is a process completed before voicing or the adjustments of the felts of the hammers. If the string sets—bichords and trichords—are not level, the strike of the corresponding hammer produces a fuzzy note and the damping of the strike is not properly accomplished. This creates what is referred to as an aftersound or ring, which, in turn, destroys the normal clarity or definition of individual notes of the instrument. In practice, piano technicians are trained to detect unlevel string sets by ear. Upon detection, the technician is presently taught to correct the condition by withdrawing the piano action and placing the end of a steel rule on the string set to sight along the string. When gaps are present, the sagging string is drawn up to the higher string by shortening or kinking the string. A complete piano action consists of thousands of parts and weighs on the order of 30 kilograms or more and hence has a substantial support or key bed on which the action rests when in the piano case. The key bed is rigidly connected to the piano case and is an integral part of the piano case. Because a mechanical coupling exists between the key bed and the piano soundboard through various components of the piano case, vibrations originating at the key bed are transmitted through the frame of the piano to the soundboard to produce extraneous noise, such as the aftersound, supra, which detract from the tonal integrity of the instrument. Consequently, in a grand piano, as the frame of the piano action is in intimate contact with the key bed, it is critical that the key bed be perfectly flat and that the string sets be precisely level with respect thereto. There are two other aspects of the grand piano manufacture and maintenance that are impacted by string leveling—the una corda pedal action for playing pianissimo and the damping mechanism for curtailing and ending the resonating of a string set. The una corda pedal in the modern grand piano is the left pedal and shifts the piano action sufficiently in the key bed to enable the piano hammers to strike only one string of each bichord unison and two strings of each trichord unison. This places a further requirement on key bed construction to permit a noiseless sliding of the piano action relative to the key bed whenever the una corda pedal is depressed. The description of the una corda pedal and the action thereof is found in a patent to Harold A. Conklin, Jr., U.S. Pat. No. 4,127,051, which description is incorporated herein by reference. In the grand piano, the damping mechanism curtails and ends the resonating of a string or string set. The depressing of a key raises a damper wire which, in turn, supports a damper head and the attached damper felt and thereafter, upon release, the damper assembly falls on the string or string set. For even damping across the entire range of the piano, the weight of the damper assembly is varied in accordance with the size and tension of the string or string set so as to have a correspondingly even damping influence on the resonance thereof. The damper felt has a longitudinal aspect which for proper damping action needs to be in full contact with the string or string set. At a pre-determined node when a string set is not level, the damping mechanism does not seat properly thereon and results in a partially damped note. This is created by one or two strings ceasing to resonate and by the remaining undamped string sustaining the note until the natural decay occurs. In manufacturing a grand piano the process of string leveling is accomplished prior to voicing which was described by Franz Mohr of Steinway as open work (or work with the piano action withdrawn from the piano case). The manufacturer anticipates that during the initial period of use, the instrument will be tuned, string leveled and voiced with greater frequency. This results as the outer portion of the hammer felts continue to be further shaped by the initial play by the pianist. Additionally, the tuning-string-leveling-voicing process takes on particular importance when a pianist individualizes the grand piano for concerts or recording sessions. When voicing is attempted without the pre-requisite string leveling, the shaping and the hardening of hammer felts do not provide the desired clarity as a hammer strike on an uneven string set produces tones with differing decays. Similarly, in regulating the mechanical arrangement of the una corda pedal, unlevel strings create a condition in which the hammer strikes, instead of squarely meeting the string (bichord) or string set (trichord), are frequently glancing blows. This produces an uneven tonal quality that is readily heard because of the pianissimo mode. The effect of unlevel string sets when adjusting the damper mechanism is described in a December, 2002 article in the Piano Technicians Journal . Andrew Remillard in an article entitled Dampers: Peace and Quiet at Last indicates that for proper adjustment of the dampers the strings need to be level because, “if one string hangs a little beneath its neighbor it will be virtually impossible to ever completely dampen it.” Prior to preparing this application, the inventor became familiar with several patents concerned with grand piano manufacture and maintenance, which patents are included herein as further background material. The patents are: ITEM NO. U.S. PAT. NO. INVENTOR ISSUE DATE 1. 6,559,369 Gilmore May 6, 2003 2. 6,489,548 Schindler Dec. 3, 2002 3. 6,479,738 Gilmore Nov. 12, 2002 4. 6,278,047 Cumberland Aug. 21, 2001 5. 6,107,556 Gilliam Aug. 22, 2000 6. 5,756,913 Gilmore May 26, 1998 7. 5,654,515 Youse Aug. 5, 1997 8. 5,528,970 Zacaroli Jun. 25, 1996 9. 5,423,241 Scarton et al. Jun. 13, 1995 10. 5,065,660 de Buda Nov. 19, 1991 11. 4,253,374 Watterman Mar. 3, 1981 12. 4,127,051 Conklin, Jr. Nov. 28, 1978 13. 3,675,529 Van Der Woerd Jul. 11, 1972 Additional background information was obtained from several nonpatent references, namely: 14. 40 TH Annual PTG Convention (1997)—Mini Technical Classes—Michael Vecchione, Making Unisons Sound SPOT ON 15. 40 TH Annual PTG Convention (1997)—Mini Technical Classes—Clair Davies, String Leveling 16. 1998 www.ptg.org—John Woodrow, String Leveling Questions 17. Del Fandrick, RPT, Q. and A. On the Level, Piano Technicians Journal ( PTJ ), Vol 38, No. 2 (1995) 18. Clair Davies, RPT String Leveling by Ear, PTJ . Vol. 40, No. 11 (1997) 19. Solution for Agraffe Noise, PTJ , Vol. 32, No. 8 (1989) 20. Q. and A. Fuzzy, False Tone, PTJ , Vol. 29, No. 3 (1986) 21. Virgil E. Smith Criminal Negligence in Piano Service, PTJ , Vol. 36, No 10 (1993) 22. David W. Pitsch, RPT, After Touch, PTJ , Vol 25, No 12 (1982) 23. Susan Graham, Agraffes, PTJ , Vol. 27, No. 5 (1984) 24. Selections from Five Lectures on The Acoustics of the Piano Proceedings of the Royal Swedish Academy of Piano (1990) as published at www.speech.kth.se In addition to the patents uncovered, the nonpatent references, as cited above, uncovered a series of five lectures entitled, The Acoustics of the Piano , sponsored by the Royal Swedish Academy of Music (1990). While there was some emphasis on aftersound and the physics of sound upon a hammer striking a string, there is seemingly no mention of the effect of unlevel strings on the voicing or on the damping mechanism. In fact, the discussion seems to indicate that some roughness at the edge of the notes was deliberate, which teaches away from the precise string leveling, infra. In Clair Davies teaching before the Piano Technicians Guild (PTG) convention about string leveling, he uses the square end of a steel rule to check that the strings are coplanar and does not use the key bed as reference. This teaching also indicates that Franz Mohr called string leveling part of the “open work” of piano tuning. With the foregoing background in mind, the purpose of the present invention is to provide a novel string leveling device which precisely gauges the condition of the bichords and trichords of a grand piano with reference to the upper surface of the key bed. The disclosed invention also encompasses a method of using the apparatus as a preliminary step to voicing a grand piano, adjusting the damping mechanism and regulating the una corda pedal. SUMMARY OF THE INVENTION Briefly, in accordance with one aspect of the present invention, an apparatus or unison gauge for indicating levelness of a string set includes a contact block adjustably engageable with the lowermost tangential aspect of the string set under examination and a set of battery powered indicators providing an indication for each string. With the piano action withdrawn from the piano case, the base of the device is designed to rest on the key bed below the piano hammer strike area of the string set and to hold the contact block, which is mounted thereon on an extendable mast or probe, with the contact face thereof in a plane parallel to the key bed. The mast can be raised or lowered to conform the gauge to the grand piano being examined. Each contact block provides at least two contact points for each string of a string set and has a corresponding indicator therefor. When in the case of a trichord with all strings level, in this embodiment, the strings contact all six contact points and completes the circuits for all three indicators. The contact block is under slight spring tension when engaged with a string set, which is being monitored and, upon release of the spring tension readily slides along the key bed to the next string set. The unison gauge of this invention brings precision to string leveling, while at the same time saving several hours of the piano technician's time. The present invention is effective in measuring the levelness of the string sets of a grand piano and is useful at the manufacturing level for quality assurance and is of even greater use in field maintenance procedures where string leveling is a preliminary step to voicing, damping mechanism adjustment, and una corde pedal regulation. The gauge is relatively small, portable, handheld, and is easy to use by a piano technician during grand piano production or field maintenance of grand pianos. In method of use of the Russo unison gauge of this invention (as the hammer strike areas of the various unisons are arrayed on a slightly arced path following the bridge of the grand piano), the gauge is first adjusted so that the altitude upon extension is slightly greater than the highest unison with respect to the key bed surface. The gauge is then aligned so that the contacts for a particular string are in line. This assures that when a 3×2 contact array is elevated to contact, for example, a trichord string set, all six contacts are in contact upon finding a level string set. If an indication of an unlevel condition occurs, the sagging string is then shortened or lifted to the right height using a string hook (or a low-effort string hook—see Reference 18 by Clair Davies, supra. OBJECTS AND FEATURES OF THE INVENTION Accordingly, it is the primary object of the present invention to provide a new and novel device to ascertain the levelness of string sets of a grand piano. It is another object of the present invention to provide a new and novel device to ascertain that the hammer strike points of a string set—namely a bichord or a trichord—lie in a line parallel to the key bed. It is yet another object of the present invention to provide a levelness device for a grand piano which is easy to use and economical to manufacture. It is still yet another object of the present invention to provide a device that eliminates piano aftersound by precisely leveling string sets. It is a feature of the present invention that the string leveling device hereof is readily moved from one string set to another and has a baseplate for using the upper surface of the key bed as a reference plane. It is another feature of the present invention that the contact surface of the string leveling device is readily raised into and lowered from tangential engagement with the string set at the hammer strike point. It is yet another feature of the present invention that the extension of the string leveling device encompasses the range of elevation of the strings sets in presently marketed grand pianos. Other objects and features of the invention will become apparent upon review of the drawing and the detailed description which follows. BRIEF DESCRIPTION OF THE DRAWING In the drawing as hereinafter described, preferred embodiments are depicted; however, various other modifications and alternate constructions can be made thereto without departing from the true spirit and scope of the invention. Also, in the drawing which follows, the same part in the various views is provided the same reference designator. FIGS. 1 and 1A are partial perspective views of a grand piano with the piano action withdrawn and the unison gauge of this invention positioned between the piano key bed and a trichord with FIG. 1 showing the details of the lyre structure, and FIG. 1A , of the damper mechanism; FIG. 2 is a partially cutaway perspective view of the unison gauge of FIG. 1 showing the mast elevation mechanism for adjusting the gauge to the piano under string leveling; FIG. 3 is a cross-sectional view of the unison gauge showing the mast extended to bring the contacts of the contact block into tangential engagement with a level trichord having a sagging string; FIG. 4 is a cross-sectional view of the unison gauge showing the mast extended to bring the contacts of the contact block into tangential engagement with the trichord being leveled; FIG. 5 is a detailed view providing a schematic representation of the indicator panel, the circuitry and power supply arrangement; FIG. 6 is a detailed view of a interchangeable contact block for the unison gauge of FIG. 2 for tangential engagement with a bichord unison; FIG. 7 is a partially cutaway perspective view of a second embodiment of the unison gauge of this invention using a series of precision base blocks to elevate the device; FIG. 8 is a partially cutaway perspective view of a third embodiment of the unison gauge of this invention, which embodiment accommodates the gauging of both bichords and trichords; and, FIG. 9 is a view of a piano technician shortening a sagging string of a string set to bring all the strings in the unison to a level condition. DESCRIPTION OF THE PREFERRED EMBODIMENTS Before embarking on the description of the device, several terms are defined for the purpose of adding clarity to this specification and the claims which follow. Here the term unison refers to a string set, which, in turn, is a bichord or trichord, that is played as one note by the percussive force of a piano hammer. The term bichord is defined as a unison or string set having two strings that is played as one note by the percussive force of a piano hammer. The term trichord is defined as a unison or string set having three strings that is played as one note by the percussive force of a piano hammer. The term voicing is defined as the final adjustment of a piano and includes trimming, hardening, needling, and, if necessary, replacing the hammer felts. The term damping mechanism adjustment is defined as the procedure by which the dampers and the damper lift mechanism are adjusted to ensure accurate damping performance. The una corda pedal is defined as the pedal for shifting the piano action so that, while the pedal is depressed, the respective piano hammers strike only one string of a bichord and only two strings of a trichord. Referring now to FIGS. 1 and 1A partial perspective views of a grand piano are shown with the piano action withdrawn and the unison gauge of this invention positioned between the piano key bed and a trichord. The Russo unison gauge is referred to generally by the reference designator 20 . A grand piano 22 , with which the unison gauge 20 of this invention is used, is shown as having a piano case 24 with a piano action 26 withdrawn therefrom. Surrounding the piano action 26 is the piano case 24 and beneath the withdrawn piano action 26 and extending rearward therefrom is a key bed 28 —a flat expanse providing support for the piano action 26 . Depending from the piano case 24 is a pedal-supporting lyre structure 30 with a una corda pedal 32 on the left side thereof. Across and atop a string assembly 34 , a damper mechanism 36 is disposed with a damper 38 to cut off the resonating of each associated string or string set 40 . In this figure, the unison gauge 20 is shown extended between the key bed 28 and the string set 40 of string assembly 34 . Referring now to FIGS. 2 and 3 are respectively perspective and sectional views of the unison gauge of the invention shown in FIG. 1 . Here the mast elevation mechanism for adjusting the external gauge range to the piano under string leveling. Each unison gauge 20 has two operating ranges, namely, (1) an external range 42 and (2) an internal range 44 . The external range 42 of a unison gauge 20 for a grand piano depends on and is fixed by the manufacturer, and as there is no industry-wide standardization, the maximum height between key bed and string set varies brand-to-brand from 6.5 to 9.5 inches. The string array 46 of string assembly 34 is slightly arcuate and in a grand piano wherein the external range is for example 7.75 inches (max.) the minimum-to-maximum range of key bed to string set heights is from 7.00 inches to 7.75 inches. This then determines the internal range 44 of operation of a unison gauge. Returning to FIG. 2 , the structure of the unison gauge 20 is next discussed. In this embodiment, the gauge 20 has a flat base 48 for emplacement of the gauge on key bed 28 . As will be ascertained from the discussion, infra, the key bed 28 is used as a reference plane and the flatness characteristic of the base 48 is translated into the precision gauging of the string set levelness. Upon the base 48 , a gauge housing 50 is constructed and receives therein a mast assembly 52 which is slidably mounted to move along an axis line 54 normal to the lower surface 56 of base 48 and the upper surface 58 of key bed 28 . The mast assembly 52 is a gear arrangement that raises and lowers the entire mast assembly 52 to a fixed position thereby setting the external range 42 . Here, the gear arrangement consists of worm or drive gear 60 and mating or driven gear 62 with the drive gear 60 rotated by control knob 64 . While shown herein by a worm gear unit, any suitable mechanical device that translates the motion into displacement along the mast axis including, but not limited to a slider-crank mechanism, a ratchet, or a rack and pinion arrangement, would be within the contemplation of this invention. Referring now to both FIGS. 2 and 3 , the mast assembly 52 is described in some detail. The mast 66 includes a support mast or fixed portion 68 and a slidable mast or movable portion 70 for extension and retraction along channel 72 of support mast 68 . Although the support mast 68 is shown as female and the slidable mast 70 is shown as male, the interengagement function is readily reversible. Likewise, the slidable mast 70 is optionally constructed as telescoping within the support mast 68 . A spring 74 extends from a lower spring holder 76 attached to base 48 to upper spring holder 78 attached to slidable mast 68 . When the spring 74 is relaxed (not compressed), the unison gauge 20 is in the fully extended condition—limited, of course, by the selected external range 42 . Medial the slidable mast portion 70 , a handle 80 is attached thereto and adapted to retracting or lowering the mast assembly 52 by compressing and holding compressed spring 74 . Compression of the spring in this manner releases the gauge that was held between the key bed and a particular unison and enables the operator to move the gauge to the next unison to be checked for levelness. Referring now to FIG. 3 a cross-sectional view is shown of the unison gauge 20 with the mast extended to bring the contacts of the contact block into tangential engagement with a level trichord. At the end of the slidable mast portion 70 opposite the base 48 , a contact block 82 is mounted thereon. The contact block 82 is constructed with the upper surface 84 thereof lying in a plane parallel to lower surface of base 48 . The upper surface 84 of contact block 82 contains contact points 86 arrayed in grid which adapts the structure for tangential engagement with the trichord being leveled. The contact block 82 has two contact points 86 for each string and, when the trichord is level, each string is in contact with both of the corresponding contact points 86 . With the geometry of the gauge as discussed above, indication that each string of the specific trichord is level shows: (1) the two contact points lie in a line 88 parallel to lower surface 56 of base 48 and upper surface 58 of key bed 28 ; (2) the six tangentially engaged contact points lie within three parallel lines 88 in upper surface 84 of contact block 82 ; and, (3) because of the internal range 44 , while the plane of each trichord may be at a slightly different altitude with respect to upper surface 58 of key bed 28 , the plane is parallel to the key bed. Referring now to FIG. 4 a cross-sectional view is shown of the unison gauge 20 with the mast extended to bring the contacts of the contact block into tangential engagement with a trichord having a sagging string. It is noted that the spring tension of spring 74 at the relaxed condition is selected so as to be insufficient to impel a sagging string of a unison to the properly aligned position. Thus, a sagging string will always create a non-indication of levelness with respect to the other strings in the string set and will not provide a level indication until the condition is remedied. The unison gauge 20 provides indication of levelness through a series of indicators. The indicators shown are battery-powered, light emitting diodes mounted on gauge housing 50 . The physical positioning of the indicators is best seen in FIGS. 2 , 3 and 4 with the circuitry in FIG. 5 . A battery compartment access panel 90 slides to one side and covers a 1.5 volt battery 92 adjacent the base 48 of unison gauge 20 . For the trichord unison 40 , a light emitting diode (LED) 94 is associated with each string of the string set. A wiring harness 96 extends from the contact block 82 mounted on the slidable mast 70 to an indicator panel 98 on gauge housing 50 . Three parallel lines accommodate the LED's 94 with the circuit for each indicator being completed by the respective string. A low battery indication is optionally provided. Referring now to FIG. 6 , an interchangeable contact block 100 is shown. This contact block is used for determining the string levelness of a bichord unison 102 . In lieu of the 3×2 matrix of contact block 82 , here a 2×2 matrix of contact points 104 is employed. For indication of levelness a two-branch parallel circuit structure 106 is associated with LED's 108 . A second embodiment of the unison gauge of this invention is shown in FIG. 7 . Here similar parts to those in the first embodiment are provided with reference designators 100 units higher than those in the first embodiment. Thus the mast assembly 152 of the second embodiment is similar to mast assembly 52 of the first embodiment. In this embodiment the means of elevating the unison gauge 120 differs from that described, supra. In lieu of an internal mechanism, precision-machined base blocks 161 and 163 that nest the one with the other and with the base 148 are used to elevate the unison gauge 120 . While these base blocks increase the external range 142 by 1-inch increments from 6.4 inches to 9.5 inches, special base blocks are optionally available for given makes of grand pianos, e.g. a Steinway block or a Kawai block. A third embodiment of the unison gauge of this invention is shown in FIG. 8 . Here similar parts to those in the first embodiment are provided with reference designators 200 units higher than those in the first embodiment. Thus the mast assembly 252 of the third embodiment is similar to mast assembly 52 of the first embodiment. In this embodiment the unison gauge 220 incorporates both a trichord mode and a bichord mode and indicates levelness in either mode. A mode switch 293 switches between a three-light set of light emitting diodes 294 with an associated three-branch, parallel circuit, as above, and a two-light set of light emitting diodes 295 with an associated two branch, parallel circuit. The contact block 282 uses the 3×2 matrix 304 thereof to ascertain the levelness of trichord unisons and upon switching modes the same (now 2×3) matrix 304 to ascertain the levelness of the bichord unisons. The technician using the gauge needs only to switch the mode and to rotate the gauge 220 at a right angle to the other mode. In operation, string leveling is performed as a preliminary step to several manufacturing and maintenance procedures for the grand piano. As indicated above, these include voicing, damping mechanism adjustment and una corda pedal action. The rationale for leveling strings is slightly different in each case but significantly each string leveling operation concerns the interaction of felted, movable mechanical parts with piano strings. When a damper head falls on a unison, if two strings are high and one is low, the low string will not be properly damped. When a hammer strikes an unlevel string set, a complex of tones, rather than a single one, emanates from the unison. When a una corda pedal is depressed, an unlevel string, which is purposely rendered inoperative by the pedal action, often catches the corner of a piano hammer and does not provide the desired pianissimo effect. String leveling is considered preliminary because the strings provide a “roadway” on which the felted, movable mechanical parts operate and it is more sensible to fix the “potholes” than all the suspension problems arising from a rough ride. A note is now inserted about selection of the external range. The selectability of the external range is only important to the Russo unison gauge user who maintains or re-manufactures a variety of grand pianos. This invention contemplates the ability to construct unison gauges operable over the entire external range without adjustment and also unison gauges which have fixed external ranges. For these reasons the selection is considered an optional step in the methodology. The general steps of string leveling are as follows: a. withdrawing the piano action from the piano case to provide access to the key bed and the strike area of the string sets; b. optionally selecting the external range for the unison gauge, with the compression capability thereof including the minimum and maximum altitudes of the string sets being leveled; c. placing the unison gauge on the key bed having the contact points of the gauge head aligned with the longitudinal axis of the strings of the string set and having a row of contact points for each string of a string set; d. compressing the unison gauge by using the handle therefor and moving the gauge head downwards towards the base; e. releasing the gauge for tangential contact between the string-set-under-test and the contact points of the gauge head; f. completing the circuit for the LED indicators and observing the display; g. shortening, as required, the sagging string of the string set, see FIG. 9 ; h. repeating steps c. through f. until all contact points are indicated as being in the same plane; i. compressing the unison gauge by using the handle therefor and moving the gauge to the next string-set-under-test; and, j. repeating steps e. through h. until all unisons have been tested for levelness. The following steps of string leveling applies to the embodiment of the unison gauge which uses two separate contact heads, namely, one for trichord and the other for bichords: a. through i. using the trichord contact head repeat steps a. through h. as in the preceding paragraph; j. (not used); k. repeating steps e. through h. until all trichords are indicated as being level; l. demounting the trichord contact head and securing in lieu thereof the bichord contact head; and m. repeating step e. through i. until all bichords are indicated as being level. While the preferred embodiment of our invention has been described fully in order to explain its principles, it is understood that various modifications or alterations may be made to the preferred embodiment without departing from the scope of the invention as set forth in the appended claims.
A unison gauge for indicating levelness of a string set of a grand piano is described. The gauge has a contact block adjustably engageable with the lowermost tangential aspect of the string set. Battery powered indicators provide an indication for each string. With the piano action withdrawn from the piano case, the base of the device rests on the key bed below the piano hammer strike area of the string set and holds the contact block mounted thereon on an extendable mast. The contacts of the contact block are in a plane parallel to the key bed. The contact block is under slight spring tension when engaged with a string set being monitored and, upon compression of the spring readily slides along the key bed to the next string set. A method of use of the unison gauge is also provided.
Summarize the document in concise, focusing on the main idea's functionality and advantages.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention This invention relates to a device for determining the levelness of compound strings or string sets, namely bichords and trichords, of a grand piano.", "The device uses the upper surface of the key bed of the piano as a reference surface and determines levelness of the aforesaid string sets.", "In addition to the string leveling device, a method of use thereof is provided.", "Description of the Prior Art The history of the modern piano begins with the pianoforte developed by a harpsichord builder, Bartolommeo Christofori.", "Christofori invented the instrument in Florence in 1709 and completed a prototype around 1720.", "The main driving force behind the instrument's development was that, in contradistinction to the predecessor instruments—the harpsichord and the clavichord—the piano provided variations in volume.", "Additionally development was spurred on by the desire to play fuller, less delicate music.", "Musicians of the time sought a full rich sound and were unsatisfied by the strong and uniform harpsichord tone produced by plucking large strings with keyboard-controlled quills.", "On the other hand, the percussive action of the clavichord, while allowing for variations in volume, produced weak tones by striking brass hammers against small, thin strings.", "Of the several versions of the piano invented in the Eighteenth century, Christofori's pianoforte, is most closely related to the modern-day grand piano in that the hammers thereof are wooden blocks covered on the striking surface with soft leather.", "Later in the Eighteenth century a piano hammer was designed with the same basic shape that survives today.", "In this design, two layers of leather were used with the inner layer being a firm leather, and the outer layer being softer.", "The final form of the leather covered piano hammer used three layers of leather of varying firmness with the softest leather on the outside and the firmest layer on the inside.", "This provided a piano hammer that was soft and compliant at the surface to provide the requisite tone for pianissimo playing and a hammer firmer underneath to provide the strength for forte playing.", "As the grand piano developed, it became more and more a solo instrument, and needed to be louder.", "To increase volume, strings needed to be thicker and the support structure stronger, so that greater tension could be achieved.", "The frame of the pianos, commonly made of wood, became thicker and heavier, and was strengthened by cross-bracing.", "By 1820, English manufacturer John Broadwood began to build iron hitch pin plates, which now meant plates were made of more metal than wood.", "In 1825 Alpheus Babcock patented the cast-iron frame and further in 1843, American manufacturer Jonas Chickering began making pianos with the full-perimeter plate—a feature of modern grand pianos.", "In 1821 a French builder, Sebastian Erard, invented the last major basic refinement of the piano action;", "the double escapement.", "Shortly thereafter, the heavy iron frame required by the action and the higher tensioned strings was provided, and then cross-stringing, a system whereby the long bass strings cross over the shorter middle-range strings, was invented.", "After the invention of the iron frame for the strings on a piano, heavier strings, including bichords and trichords, could be used at higher tensions to produce a fuller sound from the piano.", "This rendered the leather covered piano hammer unacceptable.", "The result was the development and patenting of a felt covered piano hammer by Alpheus Babcock in 1833.", "These hammers provided a more acceptable tone than the leather covered hammers.", "In the late Nineteenth century machines were invented to cover the raw wood piano hammers with felt.", "The felt hammers enabled the manufacturer to fine tune the tone of the piano by adjusting the hardness of the felt.", "The process of tonally regulating the piano hammers is called voicing, requires skilled piano technicians, and is a time consuming operation.", "Initially, the piano hammer felt is checked for proper shaping, particularly that the striking surface is flat across the width thereof.", "During voicing, the technician adjusts the tone of a hammer by adjusting the softness or the hardness of the hammer felt.", "When a tone sounds too soft, by applying a solution of lacquer and lacquer thinner to the hammer felt the technician adjusts the felt hardness and the tone produced at that site.", "Alternate methods of adjusting hammer felt hardness include working the hammer felt with a needle to loosen the fibrous structure thereof.", "String leveling of a grand piano is a process completed before voicing or the adjustments of the felts of the hammers.", "If the string sets—bichords and trichords—are not level, the strike of the corresponding hammer produces a fuzzy note and the damping of the strike is not properly accomplished.", "This creates what is referred to as an aftersound or ring, which, in turn, destroys the normal clarity or definition of individual notes of the instrument.", "In practice, piano technicians are trained to detect unlevel string sets by ear.", "Upon detection, the technician is presently taught to correct the condition by withdrawing the piano action and placing the end of a steel rule on the string set to sight along the string.", "When gaps are present, the sagging string is drawn up to the higher string by shortening or kinking the string.", "A complete piano action consists of thousands of parts and weighs on the order of 30 kilograms or more and hence has a substantial support or key bed on which the action rests when in the piano case.", "The key bed is rigidly connected to the piano case and is an integral part of the piano case.", "Because a mechanical coupling exists between the key bed and the piano soundboard through various components of the piano case, vibrations originating at the key bed are transmitted through the frame of the piano to the soundboard to produce extraneous noise, such as the aftersound, supra, which detract from the tonal integrity of the instrument.", "Consequently, in a grand piano, as the frame of the piano action is in intimate contact with the key bed, it is critical that the key bed be perfectly flat and that the string sets be precisely level with respect thereto.", "There are two other aspects of the grand piano manufacture and maintenance that are impacted by string leveling—the una corda pedal action for playing pianissimo and the damping mechanism for curtailing and ending the resonating of a string set.", "The una corda pedal in the modern grand piano is the left pedal and shifts the piano action sufficiently in the key bed to enable the piano hammers to strike only one string of each bichord unison and two strings of each trichord unison.", "This places a further requirement on key bed construction to permit a noiseless sliding of the piano action relative to the key bed whenever the una corda pedal is depressed.", "The description of the una corda pedal and the action thereof is found in a patent to Harold A. Conklin, Jr., U.S. Pat. No. 4,127,051, which description is incorporated herein by reference.", "In the grand piano, the damping mechanism curtails and ends the resonating of a string or string set.", "The depressing of a key raises a damper wire which, in turn, supports a damper head and the attached damper felt and thereafter, upon release, the damper assembly falls on the string or string set.", "For even damping across the entire range of the piano, the weight of the damper assembly is varied in accordance with the size and tension of the string or string set so as to have a correspondingly even damping influence on the resonance thereof.", "The damper felt has a longitudinal aspect which for proper damping action needs to be in full contact with the string or string set.", "At a pre-determined node when a string set is not level, the damping mechanism does not seat properly thereon and results in a partially damped note.", "This is created by one or two strings ceasing to resonate and by the remaining undamped string sustaining the note until the natural decay occurs.", "In manufacturing a grand piano the process of string leveling is accomplished prior to voicing which was described by Franz Mohr of Steinway as open work (or work with the piano action withdrawn from the piano case).", "The manufacturer anticipates that during the initial period of use, the instrument will be tuned, string leveled and voiced with greater frequency.", "This results as the outer portion of the hammer felts continue to be further shaped by the initial play by the pianist.", "Additionally, the tuning-string-leveling-voicing process takes on particular importance when a pianist individualizes the grand piano for concerts or recording sessions.", "When voicing is attempted without the pre-requisite string leveling, the shaping and the hardening of hammer felts do not provide the desired clarity as a hammer strike on an uneven string set produces tones with differing decays.", "Similarly, in regulating the mechanical arrangement of the una corda pedal, unlevel strings create a condition in which the hammer strikes, instead of squarely meeting the string (bichord) or string set (trichord), are frequently glancing blows.", "This produces an uneven tonal quality that is readily heard because of the pianissimo mode.", "The effect of unlevel string sets when adjusting the damper mechanism is described in a December, 2002 article in the Piano Technicians Journal .", "Andrew Remillard in an article entitled Dampers: Peace and Quiet at Last indicates that for proper adjustment of the dampers the strings need to be level because, “if one string hangs a little beneath its neighbor it will be virtually impossible to ever completely dampen it.”", "Prior to preparing this application, the inventor became familiar with several patents concerned with grand piano manufacture and maintenance, which patents are included herein as further background material.", "The patents are: ITEM NO.", "U.S. PAT.", "NO.", "INVENTOR ISSUE DATE 1.", "6,559,369 Gilmore May 6, 2003 2.", "6,489,548 Schindler Dec. 3, 2002 3.", "6,479,738 Gilmore Nov. 12, 2002 4.", "6,278,047 Cumberland Aug. 21, 2001 5.", "6,107,556 Gilliam Aug. 22, 2000 6.", "5,756,913 Gilmore May 26, 1998 7.", "5,654,515 Youse Aug. 5, 1997 8.", "5,528,970 Zacaroli Jun. 25, 1996 9.", "5,423,241 Scarton et al.", "Jun. 13, 1995 10.", "5,065,660 de Buda Nov. 19, 1991 11.", "4,253,374 Watterman Mar. 3, 1981 12.", "4,127,051 Conklin, Jr. Nov. 28, 1978 13.", "3,675,529 Van Der Woerd Jul. 11, 1972 Additional background information was obtained from several nonpatent references, namely: 14.", "40 TH Annual PTG Convention (1997)—Mini Technical Classes—Michael Vecchione, Making Unisons Sound SPOT ON 15.", "40 TH Annual PTG Convention (1997)—Mini Technical Classes—Clair Davies, String Leveling 16.", "1998 www.", "ptg.org—John Woodrow, String Leveling Questions 17.", "Del Fandrick, RPT, Q. and A. On the Level, Piano Technicians Journal ( PTJ ), Vol 38, No. 2 (1995) 18.", "Clair Davies, RPT String Leveling by Ear, PTJ .", "Vol. 40, No. 11 (1997) 19.", "Solution for Agraffe Noise, PTJ , Vol. 32, No. 8 (1989) 20.", "Q. and A. Fuzzy, False Tone, PTJ , Vol. 29, No. 3 (1986) 21.", "Virgil E. Smith Criminal Negligence in Piano Service, PTJ , Vol. 36, No 10 (1993) 22.", "David W. Pitsch, RPT, After Touch, PTJ , Vol 25, No 12 (1982) 23.", "Susan Graham, Agraffes, PTJ , Vol. 27, No. 5 (1984) 24.", "Selections from Five Lectures on The Acoustics of the Piano Proceedings of the Royal Swedish Academy of Piano (1990) as published at www.", "speech.", "kth.", "se In addition to the patents uncovered, the nonpatent references, as cited above, uncovered a series of five lectures entitled, The Acoustics of the Piano , sponsored by the Royal Swedish Academy of Music (1990).", "While there was some emphasis on aftersound and the physics of sound upon a hammer striking a string, there is seemingly no mention of the effect of unlevel strings on the voicing or on the damping mechanism.", "In fact, the discussion seems to indicate that some roughness at the edge of the notes was deliberate, which teaches away from the precise string leveling, infra.", "In Clair Davies teaching before the Piano Technicians Guild (PTG) convention about string leveling, he uses the square end of a steel rule to check that the strings are coplanar and does not use the key bed as reference.", "This teaching also indicates that Franz Mohr called string leveling part of the “open work”", "of piano tuning.", "With the foregoing background in mind, the purpose of the present invention is to provide a novel string leveling device which precisely gauges the condition of the bichords and trichords of a grand piano with reference to the upper surface of the key bed.", "The disclosed invention also encompasses a method of using the apparatus as a preliminary step to voicing a grand piano, adjusting the damping mechanism and regulating the una corda pedal.", "SUMMARY OF THE INVENTION Briefly, in accordance with one aspect of the present invention, an apparatus or unison gauge for indicating levelness of a string set includes a contact block adjustably engageable with the lowermost tangential aspect of the string set under examination and a set of battery powered indicators providing an indication for each string.", "With the piano action withdrawn from the piano case, the base of the device is designed to rest on the key bed below the piano hammer strike area of the string set and to hold the contact block, which is mounted thereon on an extendable mast or probe, with the contact face thereof in a plane parallel to the key bed.", "The mast can be raised or lowered to conform the gauge to the grand piano being examined.", "Each contact block provides at least two contact points for each string of a string set and has a corresponding indicator therefor.", "When in the case of a trichord with all strings level, in this embodiment, the strings contact all six contact points and completes the circuits for all three indicators.", "The contact block is under slight spring tension when engaged with a string set, which is being monitored and, upon release of the spring tension readily slides along the key bed to the next string set.", "The unison gauge of this invention brings precision to string leveling, while at the same time saving several hours of the piano technician's time.", "The present invention is effective in measuring the levelness of the string sets of a grand piano and is useful at the manufacturing level for quality assurance and is of even greater use in field maintenance procedures where string leveling is a preliminary step to voicing, damping mechanism adjustment, and una corde pedal regulation.", "The gauge is relatively small, portable, handheld, and is easy to use by a piano technician during grand piano production or field maintenance of grand pianos.", "In method of use of the Russo unison gauge of this invention (as the hammer strike areas of the various unisons are arrayed on a slightly arced path following the bridge of the grand piano), the gauge is first adjusted so that the altitude upon extension is slightly greater than the highest unison with respect to the key bed surface.", "The gauge is then aligned so that the contacts for a particular string are in line.", "This assures that when a 3×2 contact array is elevated to contact, for example, a trichord string set, all six contacts are in contact upon finding a level string set.", "If an indication of an unlevel condition occurs, the sagging string is then shortened or lifted to the right height using a string hook (or a low-effort string hook—see Reference 18 by Clair Davies, supra.", "OBJECTS AND FEATURES OF THE INVENTION Accordingly, it is the primary object of the present invention to provide a new and novel device to ascertain the levelness of string sets of a grand piano.", "It is another object of the present invention to provide a new and novel device to ascertain that the hammer strike points of a string set—namely a bichord or a trichord—lie in a line parallel to the key bed.", "It is yet another object of the present invention to provide a levelness device for a grand piano which is easy to use and economical to manufacture.", "It is still yet another object of the present invention to provide a device that eliminates piano aftersound by precisely leveling string sets.", "It is a feature of the present invention that the string leveling device hereof is readily moved from one string set to another and has a baseplate for using the upper surface of the key bed as a reference plane.", "It is another feature of the present invention that the contact surface of the string leveling device is readily raised into and lowered from tangential engagement with the string set at the hammer strike point.", "It is yet another feature of the present invention that the extension of the string leveling device encompasses the range of elevation of the strings sets in presently marketed grand pianos.", "Other objects and features of the invention will become apparent upon review of the drawing and the detailed description which follows.", "BRIEF DESCRIPTION OF THE DRAWING In the drawing as hereinafter described, preferred embodiments are depicted;", "however, various other modifications and alternate constructions can be made thereto without departing from the true spirit and scope of the invention.", "Also, in the drawing which follows, the same part in the various views is provided the same reference designator.", "FIGS. 1 and 1A are partial perspective views of a grand piano with the piano action withdrawn and the unison gauge of this invention positioned between the piano key bed and a trichord with FIG. 1 showing the details of the lyre structure, and FIG. 1A , of the damper mechanism;", "FIG. 2 is a partially cutaway perspective view of the unison gauge of FIG. 1 showing the mast elevation mechanism for adjusting the gauge to the piano under string leveling;", "FIG. 3 is a cross-sectional view of the unison gauge showing the mast extended to bring the contacts of the contact block into tangential engagement with a level trichord having a sagging string;", "FIG. 4 is a cross-sectional view of the unison gauge showing the mast extended to bring the contacts of the contact block into tangential engagement with the trichord being leveled;", "FIG. 5 is a detailed view providing a schematic representation of the indicator panel, the circuitry and power supply arrangement;", "FIG. 6 is a detailed view of a interchangeable contact block for the unison gauge of FIG. 2 for tangential engagement with a bichord unison;", "FIG. 7 is a partially cutaway perspective view of a second embodiment of the unison gauge of this invention using a series of precision base blocks to elevate the device;", "FIG. 8 is a partially cutaway perspective view of a third embodiment of the unison gauge of this invention, which embodiment accommodates the gauging of both bichords and trichords;", "and, FIG. 9 is a view of a piano technician shortening a sagging string of a string set to bring all the strings in the unison to a level condition.", "DESCRIPTION OF THE PREFERRED EMBODIMENTS Before embarking on the description of the device, several terms are defined for the purpose of adding clarity to this specification and the claims which follow.", "Here the term unison refers to a string set, which, in turn, is a bichord or trichord, that is played as one note by the percussive force of a piano hammer.", "The term bichord is defined as a unison or string set having two strings that is played as one note by the percussive force of a piano hammer.", "The term trichord is defined as a unison or string set having three strings that is played as one note by the percussive force of a piano hammer.", "The term voicing is defined as the final adjustment of a piano and includes trimming, hardening, needling, and, if necessary, replacing the hammer felts.", "The term damping mechanism adjustment is defined as the procedure by which the dampers and the damper lift mechanism are adjusted to ensure accurate damping performance.", "The una corda pedal is defined as the pedal for shifting the piano action so that, while the pedal is depressed, the respective piano hammers strike only one string of a bichord and only two strings of a trichord.", "Referring now to FIGS. 1 and 1A partial perspective views of a grand piano are shown with the piano action withdrawn and the unison gauge of this invention positioned between the piano key bed and a trichord.", "The Russo unison gauge is referred to generally by the reference designator 20 .", "A grand piano 22 , with which the unison gauge 20 of this invention is used, is shown as having a piano case 24 with a piano action 26 withdrawn therefrom.", "Surrounding the piano action 26 is the piano case 24 and beneath the withdrawn piano action 26 and extending rearward therefrom is a key bed 28 —a flat expanse providing support for the piano action 26 .", "Depending from the piano case 24 is a pedal-supporting lyre structure 30 with a una corda pedal 32 on the left side thereof.", "Across and atop a string assembly 34 , a damper mechanism 36 is disposed with a damper 38 to cut off the resonating of each associated string or string set 40 .", "In this figure, the unison gauge 20 is shown extended between the key bed 28 and the string set 40 of string assembly 34 .", "Referring now to FIGS. 2 and 3 are respectively perspective and sectional views of the unison gauge of the invention shown in FIG. 1 .", "Here the mast elevation mechanism for adjusting the external gauge range to the piano under string leveling.", "Each unison gauge 20 has two operating ranges, namely, (1) an external range 42 and (2) an internal range 44 .", "The external range 42 of a unison gauge 20 for a grand piano depends on and is fixed by the manufacturer, and as there is no industry-wide standardization, the maximum height between key bed and string set varies brand-to-brand from 6.5 to 9.5 inches.", "The string array 46 of string assembly 34 is slightly arcuate and in a grand piano wherein the external range is for example 7.75 inches (max.) the minimum-to-maximum range of key bed to string set heights is from 7.00 inches to 7.75 inches.", "This then determines the internal range 44 of operation of a unison gauge.", "Returning to FIG. 2 , the structure of the unison gauge 20 is next discussed.", "In this embodiment, the gauge 20 has a flat base 48 for emplacement of the gauge on key bed 28 .", "As will be ascertained from the discussion, infra, the key bed 28 is used as a reference plane and the flatness characteristic of the base 48 is translated into the precision gauging of the string set levelness.", "Upon the base 48 , a gauge housing 50 is constructed and receives therein a mast assembly 52 which is slidably mounted to move along an axis line 54 normal to the lower surface 56 of base 48 and the upper surface 58 of key bed 28 .", "The mast assembly 52 is a gear arrangement that raises and lowers the entire mast assembly 52 to a fixed position thereby setting the external range 42 .", "Here, the gear arrangement consists of worm or drive gear 60 and mating or driven gear 62 with the drive gear 60 rotated by control knob 64 .", "While shown herein by a worm gear unit, any suitable mechanical device that translates the motion into displacement along the mast axis including, but not limited to a slider-crank mechanism, a ratchet, or a rack and pinion arrangement, would be within the contemplation of this invention.", "Referring now to both FIGS. 2 and 3 , the mast assembly 52 is described in some detail.", "The mast 66 includes a support mast or fixed portion 68 and a slidable mast or movable portion 70 for extension and retraction along channel 72 of support mast 68 .", "Although the support mast 68 is shown as female and the slidable mast 70 is shown as male, the interengagement function is readily reversible.", "Likewise, the slidable mast 70 is optionally constructed as telescoping within the support mast 68 .", "A spring 74 extends from a lower spring holder 76 attached to base 48 to upper spring holder 78 attached to slidable mast 68 .", "When the spring 74 is relaxed (not compressed), the unison gauge 20 is in the fully extended condition—limited, of course, by the selected external range 42 .", "Medial the slidable mast portion 70 , a handle 80 is attached thereto and adapted to retracting or lowering the mast assembly 52 by compressing and holding compressed spring 74 .", "Compression of the spring in this manner releases the gauge that was held between the key bed and a particular unison and enables the operator to move the gauge to the next unison to be checked for levelness.", "Referring now to FIG. 3 a cross-sectional view is shown of the unison gauge 20 with the mast extended to bring the contacts of the contact block into tangential engagement with a level trichord.", "At the end of the slidable mast portion 70 opposite the base 48 , a contact block 82 is mounted thereon.", "The contact block 82 is constructed with the upper surface 84 thereof lying in a plane parallel to lower surface of base 48 .", "The upper surface 84 of contact block 82 contains contact points 86 arrayed in grid which adapts the structure for tangential engagement with the trichord being leveled.", "The contact block 82 has two contact points 86 for each string and, when the trichord is level, each string is in contact with both of the corresponding contact points 86 .", "With the geometry of the gauge as discussed above, indication that each string of the specific trichord is level shows: (1) the two contact points lie in a line 88 parallel to lower surface 56 of base 48 and upper surface 58 of key bed 28 ;", "(2) the six tangentially engaged contact points lie within three parallel lines 88 in upper surface 84 of contact block 82 ;", "and, (3) because of the internal range 44 , while the plane of each trichord may be at a slightly different altitude with respect to upper surface 58 of key bed 28 , the plane is parallel to the key bed.", "Referring now to FIG. 4 a cross-sectional view is shown of the unison gauge 20 with the mast extended to bring the contacts of the contact block into tangential engagement with a trichord having a sagging string.", "It is noted that the spring tension of spring 74 at the relaxed condition is selected so as to be insufficient to impel a sagging string of a unison to the properly aligned position.", "Thus, a sagging string will always create a non-indication of levelness with respect to the other strings in the string set and will not provide a level indication until the condition is remedied.", "The unison gauge 20 provides indication of levelness through a series of indicators.", "The indicators shown are battery-powered, light emitting diodes mounted on gauge housing 50 .", "The physical positioning of the indicators is best seen in FIGS. 2 , 3 and 4 with the circuitry in FIG. 5 .", "A battery compartment access panel 90 slides to one side and covers a 1.5 volt battery 92 adjacent the base 48 of unison gauge 20 .", "For the trichord unison 40 , a light emitting diode (LED) 94 is associated with each string of the string set.", "A wiring harness 96 extends from the contact block 82 mounted on the slidable mast 70 to an indicator panel 98 on gauge housing 50 .", "Three parallel lines accommodate the LED's 94 with the circuit for each indicator being completed by the respective string.", "A low battery indication is optionally provided.", "Referring now to FIG. 6 , an interchangeable contact block 100 is shown.", "This contact block is used for determining the string levelness of a bichord unison 102 .", "In lieu of the 3×2 matrix of contact block 82 , here a 2×2 matrix of contact points 104 is employed.", "For indication of levelness a two-branch parallel circuit structure 106 is associated with LED's 108 .", "A second embodiment of the unison gauge of this invention is shown in FIG. 7 .", "Here similar parts to those in the first embodiment are provided with reference designators 100 units higher than those in the first embodiment.", "Thus the mast assembly 152 of the second embodiment is similar to mast assembly 52 of the first embodiment.", "In this embodiment the means of elevating the unison gauge 120 differs from that described, supra.", "In lieu of an internal mechanism, precision-machined base blocks 161 and 163 that nest the one with the other and with the base 148 are used to elevate the unison gauge 120 .", "While these base blocks increase the external range 142 by 1-inch increments from 6.4 inches to 9.5 inches, special base blocks are optionally available for given makes of grand pianos, e.g. a Steinway block or a Kawai block.", "A third embodiment of the unison gauge of this invention is shown in FIG. 8 .", "Here similar parts to those in the first embodiment are provided with reference designators 200 units higher than those in the first embodiment.", "Thus the mast assembly 252 of the third embodiment is similar to mast assembly 52 of the first embodiment.", "In this embodiment the unison gauge 220 incorporates both a trichord mode and a bichord mode and indicates levelness in either mode.", "A mode switch 293 switches between a three-light set of light emitting diodes 294 with an associated three-branch, parallel circuit, as above, and a two-light set of light emitting diodes 295 with an associated two branch, parallel circuit.", "The contact block 282 uses the 3×2 matrix 304 thereof to ascertain the levelness of trichord unisons and upon switching modes the same (now 2×3) matrix 304 to ascertain the levelness of the bichord unisons.", "The technician using the gauge needs only to switch the mode and to rotate the gauge 220 at a right angle to the other mode.", "In operation, string leveling is performed as a preliminary step to several manufacturing and maintenance procedures for the grand piano.", "As indicated above, these include voicing, damping mechanism adjustment and una corda pedal action.", "The rationale for leveling strings is slightly different in each case but significantly each string leveling operation concerns the interaction of felted, movable mechanical parts with piano strings.", "When a damper head falls on a unison, if two strings are high and one is low, the low string will not be properly damped.", "When a hammer strikes an unlevel string set, a complex of tones, rather than a single one, emanates from the unison.", "When a una corda pedal is depressed, an unlevel string, which is purposely rendered inoperative by the pedal action, often catches the corner of a piano hammer and does not provide the desired pianissimo effect.", "String leveling is considered preliminary because the strings provide a “roadway”", "on which the felted, movable mechanical parts operate and it is more sensible to fix the “potholes”", "than all the suspension problems arising from a rough ride.", "A note is now inserted about selection of the external range.", "The selectability of the external range is only important to the Russo unison gauge user who maintains or re-manufactures a variety of grand pianos.", "This invention contemplates the ability to construct unison gauges operable over the entire external range without adjustment and also unison gauges which have fixed external ranges.", "For these reasons the selection is considered an optional step in the methodology.", "The general steps of string leveling are as follows: a. withdrawing the piano action from the piano case to provide access to the key bed and the strike area of the string sets;", "b. optionally selecting the external range for the unison gauge, with the compression capability thereof including the minimum and maximum altitudes of the string sets being leveled;", "c. placing the unison gauge on the key bed having the contact points of the gauge head aligned with the longitudinal axis of the strings of the string set and having a row of contact points for each string of a string set;", "d. compressing the unison gauge by using the handle therefor and moving the gauge head downwards towards the base;", "e. releasing the gauge for tangential contact between the string-set-under-test and the contact points of the gauge head;", "f. completing the circuit for the LED indicators and observing the display;", "g. shortening, as required, the sagging string of the string set, see FIG. 9 ;", "h. repeating steps c. through f. until all contact points are indicated as being in the same plane;", "i. compressing the unison gauge by using the handle therefor and moving the gauge to the next string-set-under-test;", "and, j. repeating steps e. through h. until all unisons have been tested for levelness.", "The following steps of string leveling applies to the embodiment of the unison gauge which uses two separate contact heads, namely, one for trichord and the other for bichords: a. through i. using the trichord contact head repeat steps a. through h. as in the preceding paragraph;", "j. (not used);", "k. repeating steps e. through h. until all trichords are indicated as being level;", "l. demounting the trichord contact head and securing in lieu thereof the bichord contact head;", "and m. repeating step e. through i. until all bichords are indicated as being level.", "While the preferred embodiment of our invention has been described fully in order to explain its principles, it is understood that various modifications or alterations may be made to the preferred embodiment without departing from the scope of the invention as set forth in the appended claims." ]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surgical instrument, commonly called a "trocar instrument" or "device," or simply a "trocar," that is used to pierce the wall of an anatomical cavity thereby forming a passageway providing communication with the inside of the cavity. Other medical instruments such as endoscopes, arthoscopes, and operating instruments can thereafter be inserted through the passageway to perform various medical procedures within the anatomical cavity. Surgical techniques using trocar devices to pierce anatomical cavity walls have recently gained great favor in the expanding field known as "least invasive surgery." Such techniques have been widely employed, for example, in gall bladder surgery and their use for other types of operations is actively being explored and implemented. These methods are desirable because the passageway formed by the trocar is small and neat. Therefore, the major trauma associated with large surgical incisions, used to perform certain operations in the past, can be avoided. The present invention provides an improved safety trocar instrument that is well suited to least invasive surgical techniques. By its design the safety trocar instrument of the present invention not only avoids the trauma that results when large incisions are made in an anatomical cavity wall, but also reduces the chance that unintended and unwanted trauma will result particularly after the instrument penetrates the wall. 2. Description of the Prior Art In its elemental form, a trocar is a device comprising an elongated shaft of, for example, surgical steel having a sharpened blade or point. Typically, least invasive surgery using such a device is performed first by inserting a fine surgical or 'Veress" needle through the cavity wall and thereafter injecting a fluid into the cavity to insufflate it and separate the cavit wall, including muscle and the peritoneum in the case of the abdomen, from other internal organs like the heart, stomach, and major blood vessels. The sharpened point of the trocar is then placed against the cavity wall and urged to pierce it by manually applying pressure to the proximal end of the shaft. An outer sleeve or "cannula" may be slid over the shaft through the wound created by the sharp point. The sleeve permits the shaft to be withdrawn from the cavity wall and maintains the passageway into the cavity. Observation and surgical instruments can then be introduced into the cavity through the sleeve. Ordinarily, the cavity wall exerts relatively large resistance to penetration by the trocar point. However, once the wall is pierced that resistance is relieved, often suddenly, so that the sharp trocar point may suddenly be urged deeply into the cavity. Therefore, the risk exists that the sharp trocar point will injure vital organs in the cavity. Accordingly, attempts have been made to reduce that risk. For example, U.S. Pat. No. 4,654,030 (Moll, et al.) discloses a safety trocar device that includes a trocar subassembly and a trocar tube subassembly that interfit with, but are separable from, one another. The trocar subassembly includes a grip, a trocar or "obturator" having a sharpened piercing tip or point, an axially reciprocally mounted tubular obturator sleeve or shield, and a compressed coil spring for urging the shield forwardly essentially to surround and shield the piercing tip of the obturator. The trocar tube subassembly includes a main body and an elongated trocar tube. The trocar device is used by inserting the obturator and shield of the trocar subassembly into the trocar tube of the trocar tube subassembly. The shield and piercing tip are together urged to extend through the lumen of the trocar tube. Ordinarily, the shield is locked in this extended position. However, when unlocked the shield may withdraw into the trocar tube against the urging of the compressed spring in the trocar subassembly. In order to pierce an anatomical cavity wall, the shield is first unlocked. Its exposed distal end is placed against the anatomical cavity wall by applying pressure to the assembly. The resistance exerted by the wall causes the shield to retract axially into the trocar tube thereby to expose the piercing tip of the obturator. Thus the tip may puncture the cavity wall. Once the tip and shield have penetrated the wall and have entered the anatomical cavity, the resistance exerted by the wall on the distal end of the shield is relieved permitting it to be urged by the compressed spring back to its extended position surrounding the piercing tip. Accordingly, once the resistance of the cavity wall on the distal end of the shield is released, the chances of injury to internal organ structures are reduced because the sharp portions of the piercing tip are again covered by the shield. U.S. Pat. No. 4,535,773 (Yoon) also relates to a safety puncturing instrument or trocar for puncturing an anatomical cavity wall and discloses several embodiments of that instrument. A number of the embodiments are conceptually similar to that disclosed in the Moll Patent and include an outer sleeve or obturator tube with an elongated section defining an interior lumen opening at a distal end and extending through to a proximal end. A thin-walled inner sleeve or shield is mounted coaxially within the outer sleeve and is urged by a compression spring to protrude from the lumen at the distal end of the outer sleeve. A trocar or obturator has a sharp blade at its distal end that can be inserted into the inner sleeve so that, when seated, the blade projects beyond the distal end of the outer sleeve but is encircled and shielded by the distal end of the inner sleeve. These embodiments of the safety puncturing instrument disclosed in the Yoon Patent are used by inserting the trocar into the inner and outer sleeves and placing the distal end of the inner sleeve against the wall of an anatomical cavity. Force is then applied to the proximal end of the trocar so that the outer sleeve and trocar blade are forced toward the cavity wall. The distal end of the inner sleeve is urged to retract within the distal end of the outer sleeve by resistance exerted by the cavity wall, thereby compressing the spring and permitting the trocar blade to be exposed to pierce the wall. When the outer sleeve enters the wound created by the trocar blade, the inner sleeve is held completely within the outer sleeve by the resistance of the cavity wall to passage of the distal ends of the outer and inner sleeves. As force continues to be applied to the proximal end of the trocar, the sharp point passes through the cavity wall and enters into the cavity. The force also causes the outer sleeve to follow through the wound. As the distal ends of the outer and inner sleeves clear the inner surface of the inside of the cavity wall, the resistance of the wall is relieved thereby releasing the inner sleeve, which is then returned to its extended position by the spring to shield the trocar blade. Safety trocars like those described above and disclosed in the Moll and Yoon Patents have certain inherent drawbacks. First, because the piercing tip of the trocar blade is generally shielded when the instrument is placed against the anatomical cavity wall, it is necessarily shielded from the surgeon's view. Therefore, he or she cannot be certain that the tip will puncture the wall at the precise location desired. Moreover, after the piercing tip has penetrated the cavity wall, it must protrude a further substantial distance into the anatomical cavity before the inner sleeve or shield is released again to cover the tip. Thus, a substantial period remains during which the tip is exposed and may injure internal organ structures. In the Yoon devices, since the inner sleeve or shield and outer sleeve may remain in the cavity after the trocar is removed, they often project a substantial distance into the cavity. Thus the available space in the cavity within which the surgeon can work is reduced. The Yoon Patent also discloses another embodiment, shown in its FIGS. 34 and 35, that includes structure for causing the sharp trocar point to retract inwardly into the outer sleeve. More particularly, this structure includes a puncturing implement or trocar having a shaft with a large diameter section at its distal end terminating in a sharp blade and a point that bears one or more electrical pressure sensors or transducer elements. An intermediate section of the trocar has a reduced diameter and is able to slide within a hollow proximal tubular section. A tension spring is coupled between the proximal end of the intermediate shaft section and a plug threaded into the proximal end of the tubular section. A detent mechanism holding a small detent is mounted in the intermediate shaft section. The detent is urged radially outwardly by a compression spring. When the intermediate shaft section is fully extended outwardly from the tubular section, the detent is coaxially aligned with and protrudes radially into a small hole in the wall of that tubular section. Thus, the shaft of the trocar is locked in the fully extended position against the urging of the coil spring, which is then held in tension. The whole assembly is carried in an outer sleeve. When the trocar is locked in the extended position, its blade extends beyond the distal end of that sleeve. Electrical leads pass through the interior of the shaft of the trocar and connect the blade sensors to electrical contacts within the detent, and in turn to an electrical socket. To use the instrument, the trocar is first locked in its outwardly extended position with the detent radially engaged in the detent hole. The trocartubular section assembly is then fitted with a handle and the distal end of the trocar is inserted into the outer sleeve. When that assembly is fully inserted into that sleeve, the detent is coaxially aligned with a radial solenoid socket adjacent the electrical socket. An electrical plug assembly includes an electrical jack that connects the leads from the blade sensors through the socket to an alarm network. The trocar assembly may then be used by pressing the blade against the anatomical cavity wall such that counterforce exerted by that wall on the blade sensors is converted to a sequential set of ready signals that trigger the alarm network. As the blade passes through the wall into the cavity interior, the counterforce is relieved from the blade sensors sequentially to produce a set of electrical signals through the alarm network. When the penetration is complete, the electrical signals from the sensors cause the alarm network to actuate the solenoid, thereby depressing the detent to permit the tension spring to retract the blade into the sleeve. An alternative detent structure is illustrated in FIG. 36 of the Yoon Patent. While in many respects this latter embodiment of the Yoon invention is an improvement over the other safety trocar designs described in the Yoon and Moll Patents, it nevertheless suffers from certain serious disadvantages. First, it depends on electrical pressure sensors or transducer elements connected to an alarm network to sense release of the counterforce exerted by the anatomical cavity wall and thereby to trigger retraction of the trocar point. Therefore, proper operation of the device may be destroyed by an electrical power failure or interruption that, even if brief, can result in serious injury to the patient. Further, the device is not self-contained but must instead be connected to the external alarm network. That alarm network may be cumbersome and the electrical leads connecting the trocar device to the alarm network may well interfere with the surgeon's work. Therefore, still additional improvement to safety trocar instrument design would be greatly beneficial to the surgical community. SUMMARY OF THE INVENTION It is a principal object of the present invention to provide an improved safety trocar instrument that mitigates the problems associated with prior devices of the type disclosed in the Moll and Yoon Patents and having a safety shield that projects forwardly to surround a sharp trocar point after the point and distal end of the shield penetrate an anatomical cavity wall. It is an additional principal object of the present invention to provide a self-contained, mechanically actuated safety trocar instrument in which a sharp trocar point is retracted into a surrounding sleeve when the sharp point has penetrated an anatomical cavity wall. The invention thereby results in a substantial improvement over known devices such as the latter embodiment described in the Yoon Patent. These and other objects are achieved by the present invention, which in a preferred embodiment includes a main body that supports an outer sleeve or cannula. The main body is configured to mate with a trocar subassembly that includes a plunger head and a main housing having a trocar. The trocar has a sharp point. The safety trocar instrument in accordance with this preferred embodiment is assembled by mating the main body-cannula subassembly with the trocar subassembly such that the trocar is received coaxially within the cannula. The trocar is urged by a retraction spring to a withdrawn rest position with the point surrounded by the distal end of the cannula. This instrument is armed to pierce an anatomical cavity wall by manually pressing the plunger head of the trocar subassembly into the main body until the sharp trocar point projects beyond the distal end of the cannula with the trocar in a fully extended position. The trocar is initially held in such attitude by an internal latching mechanism residing in the plunger head and main housing of the trocar subassembly. However, the trocar is linked to the latching mechanism through a lost-motion coupling that permits it to be urged backwardly into the housing and plunger head, to an intermediate retracted position, against the force of a pressure spring. The point is nevertheless exposed when the trocar is in the intermediate position. Once armed, the trocar instrument is used to pierce an anatomical cavity wall by pressing the exposed point of the trocar against the wall at precisely the desired location. During this operation, pressure against the trocar point urges the trocar backwardly through the lost-motion coupling to the intermediate position in a first stage to prepare a trip mechanism for disarming the latching mechanism. When the cavity wall has been completely penetrated, pressure on the trocar point is relieved permitting it again to be returned through the lost-motion coupling by the pressure spring to its fully extended position. The return of the trocar point causes the trip mechanism to fully disarm the latch mechanism thereby releasing the trocar and permitting it to be retracted to its rest position by the retractor spring with its sharp point surrounded by the distal end of the cannula. The trocar subassembly can then be removed leaving the cannula in the anatomical cavity wall to provide communication with the inside of the cavity. Thus the present invention provides a safety trocar instrument in which the sharp point of the trocar is retracted into a surrounding shield structure. Since retraction occurs immediately upon entry of the trocar point into the anatomical cavity, there is a reduced likelihood of injury to internal organs. Moreover, since retraction occurs promptly at that time, little of the device remains in the cavity after penetration to infringe upon the surgeon's work area. Still further, the trocar point is exposed to the surgeon's view at the start of penetration so that he or she can precisely position it at the desired cavity wall location. Thus the safety trocar instrument of the present invention is a substantial improvement over designs of the type disclosed in the Moll Patents and as the initial embodiments in the Yoon Patent. The present invention is also entirely self-contained and mechanically actuated. Therefore, it is not affected by electrical power failures or interruptions nor does it depend on cumbersome ancillary electrical equipment. And since no wire connections to such ancillary equipment are required, they are not present to interfere with the surgeon's work. These and other objects, aspects, features, and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (A to F) is a sequence of perspective views of the preferred embodiment of the safety trocar instrument of the present invention showing it at various stages during use; FIG. 2 is a vertical cross-sectional view of the safety trocar instrument of the present invention shown in its assembled rest condition; FIGS. 3A to 3D are a sequence of vertical cross-sectional views of the safety trocar instrument of the present invention showing it being armed and operated through initial piercing of an anatomical cavity wall; and FIGS. 4A to 4D are a sequence of vertical cross-sectional views of the safety trocar instrument of the present invention showing the trocar retraction operation and the trocar subassembly being removed from the main body-cannula assembly. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1A though 1F diagrammatically show the safety trocar instrument in accordance with the preferred embodiment of the present invention as it appears in various stages of use. More particularly, this safety trocar instrument, generally indicated at 10, includes a main body 12 having an outer tubular sleeve or cannula 14 projecting from it. The main body-cannula subassembly, generally indicated at 16, is configured to mate with a trocar subassembly generally indicated at 18, that includes a sleeve 20, mounted in a housing 22, and an elongate trocar 24, having a sharp point 26 and being mounted for axial reciprocal movement in the sleeve 20 but being urged to a retracted position therein. In the assembled rest position of the instrument 10 shown in FIG. 1A, in which the sleeve 20 and cannula 14 are partly broken away to show the location of the trocar point 26, the trocar subassembly 18 is mated with the main body-cannula subassembly 16 such that the coaxially arranged trocar 22 and sleeve 20 are in turn received coaxially within the cannula 14. As can be seen, in this rest position the distal end of the sleeve resides entirely within the distal end of the cannula and the sharp point 26 of the trocar resides within the distal end of the sleeve 20. Thus, in the rest position the sleeve and cannula 14 shield the trocar point 26. The assembled instrument is armed, as shown in FIG. 1B, to pierce an anatomical wall diagrammatically illustrated at 28, by manually squeezing the trocar subassembly 18 into the main body-cannula subassembly 16. This operation causes the sharp trocar point 26 to project beyond the distal ends of both the sleeve 20 and cannula 14. The trocar is latched in this fully extended position by an internal latching mechanism but is permitted partially to retract from the fully extended position by a lost-motion coupling. Both the latching mechanism and lost-motion coupling will be described in detail below. Thus the trocar point is exposed in preparation for puncturing the cavity wall 28. As shown in FIGS. 1B and 1C, the trocar point 26 is visible to a surgeon so that it can be precisely positioned at the desired location on an anatomical cavity wall 28 for the intended puncture wound. As the point begins penetration, counterforce exerted by the wall 28 urges the trocar 24 back toward, but not withdrawn into, the distal end of the cannula to an intermediate retracted position as permitted by the lost-motion coupling. In this intermediate position, a trip mechanism is prepared to disarm the internal latching mechanism. FIG. 1D shows the state of the trocar instrument 10 in which both the trocar point 26 and the distal ends of the sleeve 20 and cannula 14 have cleared the inside surface of the wall 28. Accordingly, the counterforce exerted by the wall on the trocar is relieved permitting it again to be projected to its fully extending position. This action causes the trip mechanism to disarm the internal latch mechanism permitting the trocar to be retracted to its rest position with the trocar point 26 shielded within the sleeve 20 and cannula 14 distal ends, as shown in FIG. 1E. In FIG. 1E the sleeve 20 and cannula 14 are shown partly broken away for clarity as in FIG. 1A. Finally, as shown in FIG. 1F, the trocar subassembly 18 can be withdrawn from the main body-cannula subassembly 16 with the cannula 14 remaining in the puncture wound in the wall 28. The cannula thus provides a passage through the cavity wall into the cavity interior. The specific structure of the safety trocar instrument 10 in accordance with a preferred embodiment of the present invention will now be described with reference to FIG. 2, which is a vertical cross-sectional view thereof. The trocar device includes the main body 12 having the cannula 14 extending therefrom. The main body 12 is formed with an intermediate partition 30, an upwardly projecting stop 32 on the partition 30, and a captured compression spring 34. The main body 12 is also formed with a generally rectangularly shaped socket 36 projecting upwardly from the partition 30. The trocar subassembly 18 is configured to mate with main body-cannula subassembly 16 and includes a main housing 38 having an integrally formed plunger head 40, and the sleeve 20, which has a radial flange 42 at its proximal end and is mounted for reciprocal movement within the housing 38. The bottom of the main housing 38 is rectangularly shaped to be telescopically received in the socket 36. The trocar 24 is mounted for axial reciprocal movement within the trocar subassembly and includes a shaft 52 having radially projecting upper and lower flanges 54 and 55 near its proximal end and the sharp point 26 at its distal end. The trocar shaft 52 is coaxially received within the sleeve 20. A stop plate 50 is received about the trocar shaft 52 between the upper and lower flanges 54 and 55 and is urged upwardly into contact with the upper radial flange 54 by a pressure spring 57. The stop plate 50, pressure spring 57, and flanges 54 and 55 constitute a lost-motion coupling, the function of which will be described in further detail below. The trocar 24 is urged to a retracted rest position by a retractor spring 56 compressed between the lower side of the stop plate 50, which engages the upper flange 54, and the sleeve flange 42. The trocar 24 is also stopped in this retracted rest position by a pair of pivotable pushers 58 mounted in the plunger head 40 that, when closed in the radial direction, engage the proximal end 59 of the trocar shaft 52, which has a reduced diameter. The pivotable pushers 58 each have a downwardly, radially outwardly tapered outer cam surface 60 that is engaged by an inner aperture in an embracing ring 62 mounted in the plunger head 40. The ring 62 is urged downwardly by a plunger spring 64 that is compressed between it and the inner surface of the top 65 of the plunger head 40. The embracing ring 62, which thus constitutes a cam driver, urges the pivotable pushers 58 radially together by engaging the tapered outer pusher surfaces 60. In addition, the trocar subassembly incorporates a latch mechanism the function of which was generally described above. Now, in detail, this latch mechanism includes latch means in the form of a pawl 68 mounted for pivoted movement on the sleeve flange 42, and an upstanding tab 76 projecting upwardly from the intermediate partition 30 in the main body through a hole in the bottom of the main housing. The pawl 68 is formed with a hook 72 at its upper end, which can override and engage an upper edge of the stop plate 50, and a foot 78 at its lower end that can engage a catch 79 at the upper end of the tab 76. A trip mechanism for the latch mechanism, comprising the tab 76 and pawl 68, includes an arm 74 pivotably mounted in the plunger head. The arm 74 has a tab 71, which can be engaged by the lower edge of the lower flange 55 to cause the arm 74 to pivot in the counterclockwise direction, and a finger 73, which can engage the foot 78 of pawl 68. It is these latch and trip mechanisms, in cooperation with the trocar flanges 54 and 55 and the stop plate 50, that determine the sequence of operations of the trocar instrument described above with reference to FIGS. 1A to 1F. More particularly, FIGS. 3A through 3D show the sequence of movements of the various elements of the safety trocar instrument described above from the rest position to arming of the instrument, and, in turn, to initial penetration of the anatomical cavity wall. In the initial rest position shown in FIG. 3A, which is substantially the same as FIG. 2, the trocar subassembly 18 is inserted into the main body-cannula subassembly 16 with the sleeve 20 and trocar shaft 52 coaxially received within the cannula 14. The distal ends of the sleeve 20 and cannula 14 terminate at nearly the same axial location, with the main housing 38 being urged outwardly from the main body 12 to its rest position by the relaxed compression spring 34. When the device is to be used, the trocar subassembly 18 is manually squeezed into main body-cannula subassembly 16 thereby compressing the captured spring 34, until the catch 79 of the tab 76 catches the foot 78 of the pawl 68 with the sleeve flange 42 abutting the stop 32, which projects through holes in the bottom of the main housing 38. At this stage, the trocar shaft is moved downwardly a small distance by the pushers 58, but the trocar point 26 remains within both the sleeve 20 and cannula 14, as shown in FIG. 3B. Further depression of plunger head 40 relative to the main housing 38 causes the pivotable pushers 58 to push the trocar shaft 54 axially downwardly further until the hook 72 of the pawl 68 overrides and catches the edge of the stop plate 50 thereby compressing the retractor spring 56. At this stage the trocar point 26 projects to a fully extended position beyond the distal ends of both the sleeve 20 and cannula 14, as shown in FIG. 3C. Those distal ends also become substantially coextensive. Ultimately, complete depression of plunger head 40 causes the sidewall of the embracing ring 62 to engage the periphery of the sleeve flange 42, which as noted has come to rest on the top of a stop 32 projecting upwardly from the intermediate partition 30. Therefore, further downward movement of the plunger head 40 causes the embracing ring 62 to move upwardly relative to the pushers 58, which are then permitted to spread radially outwardly and release the proximal end 59 of the trocar shaft 52. In this configuration, shown in FIG. 3C, the trocar instrument is armed and ready to pierce an anatomical cavity wall. The instrument can then create a puncture wound by pressing the point 26 of the trocar 24 against the cavity wall. As the point begins its entry, resistance or counterforce exerted by the wall causes the trocar shaft 52 to be urged inwardly into cannula 14 and sleeve 20, against the force of the pressure spring 57, to an intermediate retracted position until the edge of the lower flange 55 overrides the tab 71 of arm 74, as shown in FIG. 3D. The upper and lower flanges 54 and 55 in cooperation with the pressure spring 57 permit this lost trocar motion relative to the stop plate 50. FIGS. 4A to 4D show the sequence of movement of the various elements of the safety trocar instrument as the cavity wall is penetrated and retraction of the trocar point 26 is subsequently triggered. As depicted in FIG. 4A, counterforce against the point 26 of the trocar shaft 52 is relieved when the trocar and cannula 14 clear the inner surface of the cavity wall. Therefore, the pressure spring 57 may urge the trocar shaft 52 downwardly again from the intermediate position toward the fully extended position. This motion of the trocar causes the arm 74 to be pivoted in the counterclockwise direction by engagement of the edge of the lower flange 55 with the tab 71. The extreme end of the arm 74 then depresses the foot 78 of pawl 68 causing it also to pivot in the counterclockwise direction to disengage its hook 72 from the edge of the stop plate 50, thereby releasing the stop plate 50. The retractor spring 56 compressed between the flange 42 and the stop plate 50 then urges the trocar shaft 52 upwardly into the sleeve 20 and cannula 14 to its withdrawn rest position with the point shielded within the distal ends of both, as depicted in FIG. 4B. When the plunger head 40 is thereafter manually released, it may move upwardly within the main housing 38 under the influence of compressed spring 34, disengaging the sidewall of the embracing ring 62 from the periphery of the sleeve flange 42. The ring 62 may then be urged downwardly to embrace the pushers 58 and urge them together. The pushers may then again grip the proximal end 59 of the trocar shaft 52, as shown in FIG. 4C. As can also be seen there, the pawl 68 can swing about its pivot so that the foot 78 can be disengaged from the catch 79 of the leg 76. Thereafter the trocar subassembly may be removed from the main body-cannula subassembly such that the cannula remains in the anatomical cavity wall to provide communication with the cavity interior. It should be noted that the sleeve 20 in the trocar subassembly is long enough in the preferred embodiment to shield the trocar point, particularly when the trocar subassembly is in its rest condition and removed from the main body-cannula subassembly. However, the sleeve 20 may be eliminated if desired since it, by itself, is not necessary to retraction of the trocar point into the distal end of the cannula. If the sleeve is eliminated, the cannula will shield the trocar point after it is retracted following cavity penetration. Accordingly, it will be appreciated that the present invention provides an improved safety trocar instrument that retracts a sharpened trocar point into a shielding sleeve as soon as the point of the trocar penetrates an anatomical cavity wall. The instrument may be self-contained and is mechanically actuated. Therefore, reliable operation does not depend on external power supplies or electrical triggering mechanisms. Although a specific embodiment of the present invention has been described above in detail, it will be understood that this description is merely for purposes of illustration. Various modifications of and equivalent structures corresponding to the disclosed aspects of the preferred embodiment in addition to those described above may be made by those skilled in the art without departing from the spirit of the present invention which is defined in the following claims, the scope of which is to be accorded the broadest interpretation so as to encompass such modifications and equivalent structures.
A safety trocar instrument, for piercing the wall of an anatomical cavity to provide communication with the inside of the cavity, includes a tubular cannula and an elongate trocar having a sharp piercing point. The trocar is mounted for axial reciprocal movement within the cannula between a withdrawn rest position, in which the point is received within and shielded by the distal end of the cannula, a fully extended position in which the point is exposed beyond the distal end of the cannula, and an intermediate retracted position in which the point also is exposed beyond the distal end of the cannula. A retraction spring biases the trocar to its withdrawn position. A latch latches the trocar, in opposition to the retraction spring, for reciprocal movement between the fully extended and intermediate positions. A trip member couples the trocar to the latch member when the trocar moves from the fully extended position to the intermediate position, and trips the latch member when the trocar returns toward the fully extended position to unlatch the trocar and permit it to be moved to the withdrawn position by the retraction spring.
Provide a concise summary of the essential information conveyed in the given context.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention The present invention relates to a surgical instrument, commonly called a "trocar instrument"", "or "device,"", "or simply a "trocar,"", "that is used to pierce the wall of an anatomical cavity thereby forming a passageway providing communication with the inside of the cavity.", "Other medical instruments such as endoscopes, arthoscopes, and operating instruments can thereafter be inserted through the passageway to perform various medical procedures within the anatomical cavity.", "Surgical techniques using trocar devices to pierce anatomical cavity walls have recently gained great favor in the expanding field known as "least invasive surgery.", """, "Such techniques have been widely employed, for example, in gall bladder surgery and their use for other types of operations is actively being explored and implemented.", "These methods are desirable because the passageway formed by the trocar is small and neat.", "Therefore, the major trauma associated with large surgical incisions, used to perform certain operations in the past, can be avoided.", "The present invention provides an improved safety trocar instrument that is well suited to least invasive surgical techniques.", "By its design the safety trocar instrument of the present invention not only avoids the trauma that results when large incisions are made in an anatomical cavity wall, but also reduces the chance that unintended and unwanted trauma will result particularly after the instrument penetrates the wall.", "Description of the Prior Art In its elemental form, a trocar is a device comprising an elongated shaft of, for example, surgical steel having a sharpened blade or point.", "Typically, least invasive surgery using such a device is performed first by inserting a fine surgical or 'Veress"", "needle through the cavity wall and thereafter injecting a fluid into the cavity to insufflate it and separate the cavit wall, including muscle and the peritoneum in the case of the abdomen, from other internal organs like the heart, stomach, and major blood vessels.", "The sharpened point of the trocar is then placed against the cavity wall and urged to pierce it by manually applying pressure to the proximal end of the shaft.", "An outer sleeve or "cannula"", "may be slid over the shaft through the wound created by the sharp point.", "The sleeve permits the shaft to be withdrawn from the cavity wall and maintains the passageway into the cavity.", "Observation and surgical instruments can then be introduced into the cavity through the sleeve.", "Ordinarily, the cavity wall exerts relatively large resistance to penetration by the trocar point.", "However, once the wall is pierced that resistance is relieved, often suddenly, so that the sharp trocar point may suddenly be urged deeply into the cavity.", "Therefore, the risk exists that the sharp trocar point will injure vital organs in the cavity.", "Accordingly, attempts have been made to reduce that risk.", "For example, U.S. Pat. No. 4,654,030 (Moll, et al.) discloses a safety trocar device that includes a trocar subassembly and a trocar tube subassembly that interfit with, but are separable from, one another.", "The trocar subassembly includes a grip, a trocar or "obturator"", "having a sharpened piercing tip or point, an axially reciprocally mounted tubular obturator sleeve or shield, and a compressed coil spring for urging the shield forwardly essentially to surround and shield the piercing tip of the obturator.", "The trocar tube subassembly includes a main body and an elongated trocar tube.", "The trocar device is used by inserting the obturator and shield of the trocar subassembly into the trocar tube of the trocar tube subassembly.", "The shield and piercing tip are together urged to extend through the lumen of the trocar tube.", "Ordinarily, the shield is locked in this extended position.", "However, when unlocked the shield may withdraw into the trocar tube against the urging of the compressed spring in the trocar subassembly.", "In order to pierce an anatomical cavity wall, the shield is first unlocked.", "Its exposed distal end is placed against the anatomical cavity wall by applying pressure to the assembly.", "The resistance exerted by the wall causes the shield to retract axially into the trocar tube thereby to expose the piercing tip of the obturator.", "Thus the tip may puncture the cavity wall.", "Once the tip and shield have penetrated the wall and have entered the anatomical cavity, the resistance exerted by the wall on the distal end of the shield is relieved permitting it to be urged by the compressed spring back to its extended position surrounding the piercing tip.", "Accordingly, once the resistance of the cavity wall on the distal end of the shield is released, the chances of injury to internal organ structures are reduced because the sharp portions of the piercing tip are again covered by the shield.", "U.S. Pat. No. 4,535,773 (Yoon) also relates to a safety puncturing instrument or trocar for puncturing an anatomical cavity wall and discloses several embodiments of that instrument.", "A number of the embodiments are conceptually similar to that disclosed in the Moll Patent and include an outer sleeve or obturator tube with an elongated section defining an interior lumen opening at a distal end and extending through to a proximal end.", "A thin-walled inner sleeve or shield is mounted coaxially within the outer sleeve and is urged by a compression spring to protrude from the lumen at the distal end of the outer sleeve.", "A trocar or obturator has a sharp blade at its distal end that can be inserted into the inner sleeve so that, when seated, the blade projects beyond the distal end of the outer sleeve but is encircled and shielded by the distal end of the inner sleeve.", "These embodiments of the safety puncturing instrument disclosed in the Yoon Patent are used by inserting the trocar into the inner and outer sleeves and placing the distal end of the inner sleeve against the wall of an anatomical cavity.", "Force is then applied to the proximal end of the trocar so that the outer sleeve and trocar blade are forced toward the cavity wall.", "The distal end of the inner sleeve is urged to retract within the distal end of the outer sleeve by resistance exerted by the cavity wall, thereby compressing the spring and permitting the trocar blade to be exposed to pierce the wall.", "When the outer sleeve enters the wound created by the trocar blade, the inner sleeve is held completely within the outer sleeve by the resistance of the cavity wall to passage of the distal ends of the outer and inner sleeves.", "As force continues to be applied to the proximal end of the trocar, the sharp point passes through the cavity wall and enters into the cavity.", "The force also causes the outer sleeve to follow through the wound.", "As the distal ends of the outer and inner sleeves clear the inner surface of the inside of the cavity wall, the resistance of the wall is relieved thereby releasing the inner sleeve, which is then returned to its extended position by the spring to shield the trocar blade.", "Safety trocars like those described above and disclosed in the Moll and Yoon Patents have certain inherent drawbacks.", "First, because the piercing tip of the trocar blade is generally shielded when the instrument is placed against the anatomical cavity wall, it is necessarily shielded from the surgeon's view.", "Therefore, he or she cannot be certain that the tip will puncture the wall at the precise location desired.", "Moreover, after the piercing tip has penetrated the cavity wall, it must protrude a further substantial distance into the anatomical cavity before the inner sleeve or shield is released again to cover the tip.", "Thus, a substantial period remains during which the tip is exposed and may injure internal organ structures.", "In the Yoon devices, since the inner sleeve or shield and outer sleeve may remain in the cavity after the trocar is removed, they often project a substantial distance into the cavity.", "Thus the available space in the cavity within which the surgeon can work is reduced.", "The Yoon Patent also discloses another embodiment, shown in its FIGS. 34 and 35, that includes structure for causing the sharp trocar point to retract inwardly into the outer sleeve.", "More particularly, this structure includes a puncturing implement or trocar having a shaft with a large diameter section at its distal end terminating in a sharp blade and a point that bears one or more electrical pressure sensors or transducer elements.", "An intermediate section of the trocar has a reduced diameter and is able to slide within a hollow proximal tubular section.", "A tension spring is coupled between the proximal end of the intermediate shaft section and a plug threaded into the proximal end of the tubular section.", "A detent mechanism holding a small detent is mounted in the intermediate shaft section.", "The detent is urged radially outwardly by a compression spring.", "When the intermediate shaft section is fully extended outwardly from the tubular section, the detent is coaxially aligned with and protrudes radially into a small hole in the wall of that tubular section.", "Thus, the shaft of the trocar is locked in the fully extended position against the urging of the coil spring, which is then held in tension.", "The whole assembly is carried in an outer sleeve.", "When the trocar is locked in the extended position, its blade extends beyond the distal end of that sleeve.", "Electrical leads pass through the interior of the shaft of the trocar and connect the blade sensors to electrical contacts within the detent, and in turn to an electrical socket.", "To use the instrument, the trocar is first locked in its outwardly extended position with the detent radially engaged in the detent hole.", "The trocartubular section assembly is then fitted with a handle and the distal end of the trocar is inserted into the outer sleeve.", "When that assembly is fully inserted into that sleeve, the detent is coaxially aligned with a radial solenoid socket adjacent the electrical socket.", "An electrical plug assembly includes an electrical jack that connects the leads from the blade sensors through the socket to an alarm network.", "The trocar assembly may then be used by pressing the blade against the anatomical cavity wall such that counterforce exerted by that wall on the blade sensors is converted to a sequential set of ready signals that trigger the alarm network.", "As the blade passes through the wall into the cavity interior, the counterforce is relieved from the blade sensors sequentially to produce a set of electrical signals through the alarm network.", "When the penetration is complete, the electrical signals from the sensors cause the alarm network to actuate the solenoid, thereby depressing the detent to permit the tension spring to retract the blade into the sleeve.", "An alternative detent structure is illustrated in FIG. 36 of the Yoon Patent.", "While in many respects this latter embodiment of the Yoon invention is an improvement over the other safety trocar designs described in the Yoon and Moll Patents, it nevertheless suffers from certain serious disadvantages.", "First, it depends on electrical pressure sensors or transducer elements connected to an alarm network to sense release of the counterforce exerted by the anatomical cavity wall and thereby to trigger retraction of the trocar point.", "Therefore, proper operation of the device may be destroyed by an electrical power failure or interruption that, even if brief, can result in serious injury to the patient.", "Further, the device is not self-contained but must instead be connected to the external alarm network.", "That alarm network may be cumbersome and the electrical leads connecting the trocar device to the alarm network may well interfere with the surgeon's work.", "Therefore, still additional improvement to safety trocar instrument design would be greatly beneficial to the surgical community.", "SUMMARY OF THE INVENTION It is a principal object of the present invention to provide an improved safety trocar instrument that mitigates the problems associated with prior devices of the type disclosed in the Moll and Yoon Patents and having a safety shield that projects forwardly to surround a sharp trocar point after the point and distal end of the shield penetrate an anatomical cavity wall.", "It is an additional principal object of the present invention to provide a self-contained, mechanically actuated safety trocar instrument in which a sharp trocar point is retracted into a surrounding sleeve when the sharp point has penetrated an anatomical cavity wall.", "The invention thereby results in a substantial improvement over known devices such as the latter embodiment described in the Yoon Patent.", "These and other objects are achieved by the present invention, which in a preferred embodiment includes a main body that supports an outer sleeve or cannula.", "The main body is configured to mate with a trocar subassembly that includes a plunger head and a main housing having a trocar.", "The trocar has a sharp point.", "The safety trocar instrument in accordance with this preferred embodiment is assembled by mating the main body-cannula subassembly with the trocar subassembly such that the trocar is received coaxially within the cannula.", "The trocar is urged by a retraction spring to a withdrawn rest position with the point surrounded by the distal end of the cannula.", "This instrument is armed to pierce an anatomical cavity wall by manually pressing the plunger head of the trocar subassembly into the main body until the sharp trocar point projects beyond the distal end of the cannula with the trocar in a fully extended position.", "The trocar is initially held in such attitude by an internal latching mechanism residing in the plunger head and main housing of the trocar subassembly.", "However, the trocar is linked to the latching mechanism through a lost-motion coupling that permits it to be urged backwardly into the housing and plunger head, to an intermediate retracted position, against the force of a pressure spring.", "The point is nevertheless exposed when the trocar is in the intermediate position.", "Once armed, the trocar instrument is used to pierce an anatomical cavity wall by pressing the exposed point of the trocar against the wall at precisely the desired location.", "During this operation, pressure against the trocar point urges the trocar backwardly through the lost-motion coupling to the intermediate position in a first stage to prepare a trip mechanism for disarming the latching mechanism.", "When the cavity wall has been completely penetrated, pressure on the trocar point is relieved permitting it again to be returned through the lost-motion coupling by the pressure spring to its fully extended position.", "The return of the trocar point causes the trip mechanism to fully disarm the latch mechanism thereby releasing the trocar and permitting it to be retracted to its rest position by the retractor spring with its sharp point surrounded by the distal end of the cannula.", "The trocar subassembly can then be removed leaving the cannula in the anatomical cavity wall to provide communication with the inside of the cavity.", "Thus the present invention provides a safety trocar instrument in which the sharp point of the trocar is retracted into a surrounding shield structure.", "Since retraction occurs immediately upon entry of the trocar point into the anatomical cavity, there is a reduced likelihood of injury to internal organs.", "Moreover, since retraction occurs promptly at that time, little of the device remains in the cavity after penetration to infringe upon the surgeon's work area.", "Still further, the trocar point is exposed to the surgeon's view at the start of penetration so that he or she can precisely position it at the desired cavity wall location.", "Thus the safety trocar instrument of the present invention is a substantial improvement over designs of the type disclosed in the Moll Patents and as the initial embodiments in the Yoon Patent.", "The present invention is also entirely self-contained and mechanically actuated.", "Therefore, it is not affected by electrical power failures or interruptions nor does it depend on cumbersome ancillary electrical equipment.", "And since no wire connections to such ancillary equipment are required, they are not present to interfere with the surgeon's work.", "These and other objects, aspects, features, and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (A to F) is a sequence of perspective views of the preferred embodiment of the safety trocar instrument of the present invention showing it at various stages during use;", "FIG. 2 is a vertical cross-sectional view of the safety trocar instrument of the present invention shown in its assembled rest condition;", "FIGS. 3A to 3D are a sequence of vertical cross-sectional views of the safety trocar instrument of the present invention showing it being armed and operated through initial piercing of an anatomical cavity wall;", "and FIGS. 4A to 4D are a sequence of vertical cross-sectional views of the safety trocar instrument of the present invention showing the trocar retraction operation and the trocar subassembly being removed from the main body-cannula assembly.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1A though 1F diagrammatically show the safety trocar instrument in accordance with the preferred embodiment of the present invention as it appears in various stages of use.", "More particularly, this safety trocar instrument, generally indicated at 10, includes a main body 12 having an outer tubular sleeve or cannula 14 projecting from it.", "The main body-cannula subassembly, generally indicated at 16, is configured to mate with a trocar subassembly generally indicated at 18, that includes a sleeve 20, mounted in a housing 22, and an elongate trocar 24, having a sharp point 26 and being mounted for axial reciprocal movement in the sleeve 20 but being urged to a retracted position therein.", "In the assembled rest position of the instrument 10 shown in FIG. 1A, in which the sleeve 20 and cannula 14 are partly broken away to show the location of the trocar point 26, the trocar subassembly 18 is mated with the main body-cannula subassembly 16 such that the coaxially arranged trocar 22 and sleeve 20 are in turn received coaxially within the cannula 14.", "As can be seen, in this rest position the distal end of the sleeve resides entirely within the distal end of the cannula and the sharp point 26 of the trocar resides within the distal end of the sleeve 20.", "Thus, in the rest position the sleeve and cannula 14 shield the trocar point 26.", "The assembled instrument is armed, as shown in FIG. 1B, to pierce an anatomical wall diagrammatically illustrated at 28, by manually squeezing the trocar subassembly 18 into the main body-cannula subassembly 16.", "This operation causes the sharp trocar point 26 to project beyond the distal ends of both the sleeve 20 and cannula 14.", "The trocar is latched in this fully extended position by an internal latching mechanism but is permitted partially to retract from the fully extended position by a lost-motion coupling.", "Both the latching mechanism and lost-motion coupling will be described in detail below.", "Thus the trocar point is exposed in preparation for puncturing the cavity wall 28.", "As shown in FIGS. 1B and 1C, the trocar point 26 is visible to a surgeon so that it can be precisely positioned at the desired location on an anatomical cavity wall 28 for the intended puncture wound.", "As the point begins penetration, counterforce exerted by the wall 28 urges the trocar 24 back toward, but not withdrawn into, the distal end of the cannula to an intermediate retracted position as permitted by the lost-motion coupling.", "In this intermediate position, a trip mechanism is prepared to disarm the internal latching mechanism.", "FIG. 1D shows the state of the trocar instrument 10 in which both the trocar point 26 and the distal ends of the sleeve 20 and cannula 14 have cleared the inside surface of the wall 28.", "Accordingly, the counterforce exerted by the wall on the trocar is relieved permitting it again to be projected to its fully extending position.", "This action causes the trip mechanism to disarm the internal latch mechanism permitting the trocar to be retracted to its rest position with the trocar point 26 shielded within the sleeve 20 and cannula 14 distal ends, as shown in FIG. 1E.", "In FIG. 1E the sleeve 20 and cannula 14 are shown partly broken away for clarity as in FIG. 1A.", "Finally, as shown in FIG. 1F, the trocar subassembly 18 can be withdrawn from the main body-cannula subassembly 16 with the cannula 14 remaining in the puncture wound in the wall 28.", "The cannula thus provides a passage through the cavity wall into the cavity interior.", "The specific structure of the safety trocar instrument 10 in accordance with a preferred embodiment of the present invention will now be described with reference to FIG. 2, which is a vertical cross-sectional view thereof.", "The trocar device includes the main body 12 having the cannula 14 extending therefrom.", "The main body 12 is formed with an intermediate partition 30, an upwardly projecting stop 32 on the partition 30, and a captured compression spring 34.", "The main body 12 is also formed with a generally rectangularly shaped socket 36 projecting upwardly from the partition 30.", "The trocar subassembly 18 is configured to mate with main body-cannula subassembly 16 and includes a main housing 38 having an integrally formed plunger head 40, and the sleeve 20, which has a radial flange 42 at its proximal end and is mounted for reciprocal movement within the housing 38.", "The bottom of the main housing 38 is rectangularly shaped to be telescopically received in the socket 36.", "The trocar 24 is mounted for axial reciprocal movement within the trocar subassembly and includes a shaft 52 having radially projecting upper and lower flanges 54 and 55 near its proximal end and the sharp point 26 at its distal end.", "The trocar shaft 52 is coaxially received within the sleeve 20.", "A stop plate 50 is received about the trocar shaft 52 between the upper and lower flanges 54 and 55 and is urged upwardly into contact with the upper radial flange 54 by a pressure spring 57.", "The stop plate 50, pressure spring 57, and flanges 54 and 55 constitute a lost-motion coupling, the function of which will be described in further detail below.", "The trocar 24 is urged to a retracted rest position by a retractor spring 56 compressed between the lower side of the stop plate 50, which engages the upper flange 54, and the sleeve flange 42.", "The trocar 24 is also stopped in this retracted rest position by a pair of pivotable pushers 58 mounted in the plunger head 40 that, when closed in the radial direction, engage the proximal end 59 of the trocar shaft 52, which has a reduced diameter.", "The pivotable pushers 58 each have a downwardly, radially outwardly tapered outer cam surface 60 that is engaged by an inner aperture in an embracing ring 62 mounted in the plunger head 40.", "The ring 62 is urged downwardly by a plunger spring 64 that is compressed between it and the inner surface of the top 65 of the plunger head 40.", "The embracing ring 62, which thus constitutes a cam driver, urges the pivotable pushers 58 radially together by engaging the tapered outer pusher surfaces 60.", "In addition, the trocar subassembly incorporates a latch mechanism the function of which was generally described above.", "Now, in detail, this latch mechanism includes latch means in the form of a pawl 68 mounted for pivoted movement on the sleeve flange 42, and an upstanding tab 76 projecting upwardly from the intermediate partition 30 in the main body through a hole in the bottom of the main housing.", "The pawl 68 is formed with a hook 72 at its upper end, which can override and engage an upper edge of the stop plate 50, and a foot 78 at its lower end that can engage a catch 79 at the upper end of the tab 76.", "A trip mechanism for the latch mechanism, comprising the tab 76 and pawl 68, includes an arm 74 pivotably mounted in the plunger head.", "The arm 74 has a tab 71, which can be engaged by the lower edge of the lower flange 55 to cause the arm 74 to pivot in the counterclockwise direction, and a finger 73, which can engage the foot 78 of pawl 68.", "It is these latch and trip mechanisms, in cooperation with the trocar flanges 54 and 55 and the stop plate 50, that determine the sequence of operations of the trocar instrument described above with reference to FIGS. 1A to 1F.", "More particularly, FIGS. 3A through 3D show the sequence of movements of the various elements of the safety trocar instrument described above from the rest position to arming of the instrument, and, in turn, to initial penetration of the anatomical cavity wall.", "In the initial rest position shown in FIG. 3A, which is substantially the same as FIG. 2, the trocar subassembly 18 is inserted into the main body-cannula subassembly 16 with the sleeve 20 and trocar shaft 52 coaxially received within the cannula 14.", "The distal ends of the sleeve 20 and cannula 14 terminate at nearly the same axial location, with the main housing 38 being urged outwardly from the main body 12 to its rest position by the relaxed compression spring 34.", "When the device is to be used, the trocar subassembly 18 is manually squeezed into main body-cannula subassembly 16 thereby compressing the captured spring 34, until the catch 79 of the tab 76 catches the foot 78 of the pawl 68 with the sleeve flange 42 abutting the stop 32, which projects through holes in the bottom of the main housing 38.", "At this stage, the trocar shaft is moved downwardly a small distance by the pushers 58, but the trocar point 26 remains within both the sleeve 20 and cannula 14, as shown in FIG. 3B.", "Further depression of plunger head 40 relative to the main housing 38 causes the pivotable pushers 58 to push the trocar shaft 54 axially downwardly further until the hook 72 of the pawl 68 overrides and catches the edge of the stop plate 50 thereby compressing the retractor spring 56.", "At this stage the trocar point 26 projects to a fully extended position beyond the distal ends of both the sleeve 20 and cannula 14, as shown in FIG. 3C.", "Those distal ends also become substantially coextensive.", "Ultimately, complete depression of plunger head 40 causes the sidewall of the embracing ring 62 to engage the periphery of the sleeve flange 42, which as noted has come to rest on the top of a stop 32 projecting upwardly from the intermediate partition 30.", "Therefore, further downward movement of the plunger head 40 causes the embracing ring 62 to move upwardly relative to the pushers 58, which are then permitted to spread radially outwardly and release the proximal end 59 of the trocar shaft 52.", "In this configuration, shown in FIG. 3C, the trocar instrument is armed and ready to pierce an anatomical cavity wall.", "The instrument can then create a puncture wound by pressing the point 26 of the trocar 24 against the cavity wall.", "As the point begins its entry, resistance or counterforce exerted by the wall causes the trocar shaft 52 to be urged inwardly into cannula 14 and sleeve 20, against the force of the pressure spring 57, to an intermediate retracted position until the edge of the lower flange 55 overrides the tab 71 of arm 74, as shown in FIG. 3D.", "The upper and lower flanges 54 and 55 in cooperation with the pressure spring 57 permit this lost trocar motion relative to the stop plate 50.", "FIGS. 4A to 4D show the sequence of movement of the various elements of the safety trocar instrument as the cavity wall is penetrated and retraction of the trocar point 26 is subsequently triggered.", "As depicted in FIG. 4A, counterforce against the point 26 of the trocar shaft 52 is relieved when the trocar and cannula 14 clear the inner surface of the cavity wall.", "Therefore, the pressure spring 57 may urge the trocar shaft 52 downwardly again from the intermediate position toward the fully extended position.", "This motion of the trocar causes the arm 74 to be pivoted in the counterclockwise direction by engagement of the edge of the lower flange 55 with the tab 71.", "The extreme end of the arm 74 then depresses the foot 78 of pawl 68 causing it also to pivot in the counterclockwise direction to disengage its hook 72 from the edge of the stop plate 50, thereby releasing the stop plate 50.", "The retractor spring 56 compressed between the flange 42 and the stop plate 50 then urges the trocar shaft 52 upwardly into the sleeve 20 and cannula 14 to its withdrawn rest position with the point shielded within the distal ends of both, as depicted in FIG. 4B.", "When the plunger head 40 is thereafter manually released, it may move upwardly within the main housing 38 under the influence of compressed spring 34, disengaging the sidewall of the embracing ring 62 from the periphery of the sleeve flange 42.", "The ring 62 may then be urged downwardly to embrace the pushers 58 and urge them together.", "The pushers may then again grip the proximal end 59 of the trocar shaft 52, as shown in FIG. 4C.", "As can also be seen there, the pawl 68 can swing about its pivot so that the foot 78 can be disengaged from the catch 79 of the leg 76.", "Thereafter the trocar subassembly may be removed from the main body-cannula subassembly such that the cannula remains in the anatomical cavity wall to provide communication with the cavity interior.", "It should be noted that the sleeve 20 in the trocar subassembly is long enough in the preferred embodiment to shield the trocar point, particularly when the trocar subassembly is in its rest condition and removed from the main body-cannula subassembly.", "However, the sleeve 20 may be eliminated if desired since it, by itself, is not necessary to retraction of the trocar point into the distal end of the cannula.", "If the sleeve is eliminated, the cannula will shield the trocar point after it is retracted following cavity penetration.", "Accordingly, it will be appreciated that the present invention provides an improved safety trocar instrument that retracts a sharpened trocar point into a shielding sleeve as soon as the point of the trocar penetrates an anatomical cavity wall.", "The instrument may be self-contained and is mechanically actuated.", "Therefore, reliable operation does not depend on external power supplies or electrical triggering mechanisms.", "Although a specific embodiment of the present invention has been described above in detail, it will be understood that this description is merely for purposes of illustration.", "Various modifications of and equivalent structures corresponding to the disclosed aspects of the preferred embodiment in addition to those described above may be made by those skilled in the art without departing from the spirit of the present invention which is defined in the following claims, the scope of which is to be accorded the broadest interpretation so as to encompass such modifications and equivalent structures." ]
CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a division of U.S. patent application Ser. No. 13/430,925 filed Mar. 27, 2012. BACKGROUND [0002] This disclosure relates to ram air turbines utilized to provide emergency power for an aircraft. More particularly, this disclosure relates to controlling fluid within a ram air turbine that supplies both electric and hydraulic power to an aircraft. [0003] A ram air turbine is used to generate supplemental power in an aircraft by extracting power from an air stream along the exterior of the aircraft during flight. The ram air turbine includes a turbine that drives an electric motor or hydraulic pump. In operation, the turbine is moved from a stowed position within the aircraft to a position that provides clearance for blades of the turbine and the aircraft. The turbine is mounted at the end of a strut and drives a turbine drive shaft that in turn drives the electric motor or hydraulic pump. Hydraulic fluid from the hydraulic pump may be damaging to generator components. SUMMARY [0004] A method of controlling fluid flow in a ram air turbine assembly according to an exemplary aspect of the present disclosure includes, among other things, redirecting flow moving in an axial direction against the surface of a drive shaft to flow moving in a radial direction away from the drive shaft to limit flow of the fluid from a hydraulic pump to a generator. [0005] In a further non-limiting embodiment of the foregoing method, the method includes using a radially extending feature of the drive shaft to initiate the redirecting. [0006] In a further non-limiting embodiment of any of the foregoing methods, the method includes driving the hydraulic pump and the generator using the drive shaft. [0007] In a further non-limiting embodiment of any of the foregoing methods, the method includes rotating a turbine of a ram air turbine to rotate the drive shaft. [0008] In a further non-limiting embodiment of any of the foregoing methods, the fluid is a hydraulic fluid. [0009] In a further non-limiting embodiment of any of the foregoing methods, the method includes moving a strut from a stowed position to a deployed position, and redirecting after the deploying. [0010] In a further non-limiting embodiment of any of the foregoing methods, the method includes rotating the drive shaft about a drive shaft axis to directly drive the hydraulic pump and the generator when the strut is in the deployed position. [0011] In a further non-limiting embodiment of any of the foregoing methods, the method includes supporting a turbine within the strut, the strut connected to a turbine shaft that rotates about a turbine shaft axis transverse to the drive shaft axis. [0012] In a further non-limiting embodiment of any of the foregoing methods, the method includes redirecting flow moving in the axial direction to flow moving in the radial direction into an annular cavity. [0013] In a further non-limiting embodiment of any of the foregoing methods, the method includes holding at least a portion of both the hydraulic pump and the generator within a housing assembly and providing the annular cavity within the housing assembly. [0014] In a further non-limiting embodiment of any of the foregoing methods, the method includes draining the fluid from the annular cavity using a conduit. [0015] In a further non-limiting embodiment of any of the foregoing methods, the drive shaft, the hydraulic pump, and the generator are axially aligned. [0016] In a further non-limiting embodiment of any of the foregoing methods, the generator is axially closer to the turbine than the hydraulic pump. [0017] In a further non-limiting embodiment of any of the foregoing methods, the method includes redirecting using an interruption in the drive shaft. [0018] In a further non-limiting embodiment of any of the foregoing methods, the interruption extends circumferentially and continuously about the entire axis. [0019] In a further non-limiting embodiment of any of the foregoing methods, the interruption comprises a first rib extending radially from the drive shaft and a second rib extending radially from the drive shaft, the first rib axially spaced from the second rib. [0020] A method of controlling flow in a ram air turbine according to another exemplary aspect of the present disclosure includes, among other things, rotating a turbine to rotate a turbine shaft about a turbine shaft axis when a ram air turbine is in a deployed position, rotating a drive shaft about a turbine shaft axis with the turbine shaft, the turbine shaft rotating about a turbine shaft axis that is transverse to the drive shaft axis, driving a hydraulic pump and a generator with the drive shaft, and redirecting a fluid flowing from the hydraulic pump to a generator into an cavity provided by a housing of the ram air turbine. [0021] In a further non-limiting embodiment of the foregoing method, the cavity is an annular cavity. [0022] In a further non-limiting embodiment of any of the foregoing methods, the method includes redirecting using an interruption in the drive shaft. [0023] In a further non-limiting embodiment of any of the foregoing methods, the method includes holding the hydraulic pump, the generator, or both within the housing. DESCRIPTION OF THE FIGURES [0024] The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures that accompany the detailed description can be briefly described as follows: [0025] FIG. 1 is a schematic view of an example ram air turbine including a generator and a hydraulic pump. [0026] FIG. 2 is a sectional view of the FIG. 1 ram air turbine. [0027] FIG. 3 is a close-up sectional view of an interface between the generator and the hydraulic pump of the FIG. 1 ram air turbine. DETAILED DESCRIPTION [0028] Referring to FIGS. 1 and 2 , an example ram air turbine assembly (RAT) 10 is mounted to an airframe 12 and is deployable to provide both electric power and hydraulic pressure. The example RAT 10 includes a turbine 14 that rotates responsive to air flow along the outside of the airframe 12 . The turbine 14 is supported at the end of strut 22 attached to a generator housing 24 . The generator housing 24 is mounted for rotation to the airframe 12 with a swivel post 28 . [0029] A generator 32 disposed within the generator housing 24 is coupled to a hydraulic pump 38 . The generator 32 generates electric power that can be supplied to an aircraft system such as is schematically indicated at 40 . The hydraulic pump 38 receives fluid from a fluid supply 44 and pumps the fluid to various systems indicated at 42 that utilize pressurized fluid for operation. [0030] The turbine 14 rotates to drive a turbine shaft 46 about an axis 48 . The turbine shaft 46 drives a gearbox 50 . The example gearbox 50 is disposed aft of the turbine 14 and along the axis 48 of rotation of the turbine 14 and turbine shaft 46 . The example gearbox 50 drives a drive shaft 52 that rotates about an axis 54 that is transverse to the axis 48 . The drive shaft 52 extends from the gearbox 16 through the strut 22 to the generator 32 . The drive shaft 52 is coupled to drive the generator 32 at a desired speed. [0031] The example gearbox 50 includes gears that provide a desired ratio of rotational speed between the turbine shaft 46 and the drive shaft 52 . In this example, the drive shaft 52 is rotated at a greater speed than the turbine shaft 46 . The gearbox 50 can be configured to provide any desired speed ratio relative to rotation of the turbine 14 . [0032] The speed at which the drive shaft 52 is rotated is determined to provide the desired rotational speed required to drive the generator 32 and produce a desired amount of electrical energy at the desired frequency. The electrical energy produced by the generator 32 is then transmitted to the aircraft system schematically indicated at 40 . [0033] A second drive shaft 56 couples the hydraulic pump 38 in rotation with the generator 32 such that the hydraulic pump 38 rotates at the same speed as the generator 32 . As the hydraulic pump 38 and the generator 32 are coupled to rotate together, the hydraulic pump 20 communicates pressurized fluid to the aircraft systems 40 at the same time as the generator 18 produces electric power. [0034] The generator 18 is supported within the generator housing 24 at an end distal from the turbine 14 . The generator housing 24 includes a mounting bracket 60 and an integral swivel bracket 58 . The mounting bracket 60 attaches to an actuator 62 . The actuator 62 drives movement of the RAT 10 between a stowed position within the airframe 12 and the deployed position schematically shown in FIG. 1 . [0035] The swivel bracket 58 mounts to the swivel post 28 to support the RAT 10 . The strut 22 is attached to the generator housing 24 and therefore moves with the pivoting movement of the generator housing 24 . The hydraulic pump 20 is mounted to the generator housing 24 and therefore also rotates with the generator housing 24 during movement to the deployed position. [0036] Referring to FIG. 3 , the second drive shaft 56 is rotated by the main drive shaft 52 through a spline connection 66 . The second drive shaft 56 couples rotation of rotors within the generator 32 with rotation of the hydraulic pump 38 . In other examples, the second drive shaft 56 is not a separate shaft but is instead a continuation of the drive shaft 52 . [0037] The hydraulic pump 38 is mostly vertically above the generator 32 when the RAT 10 is deployed. When deployed, some of the face seal leakage flows from the hydraulic pump 38 against an exterior surface 68 of the second drive shaft 56 , and toward the generator 32 . The example fluid is hydraulic fluid such as Skydrol® or some other type of phosphate ester hydraulic fluid. The fluid can damage components of the generator 32 as is known. When not deployed, the fluid is not in a position to flow downward along the exterior surface 68 . [0038] The example second drive shaft 56 includes an interruption 70 that limits flow of fluid from the hydraulic pump 38 to the generator 32 . The interruption 70 is axially between the hydraulic pump 38 and the generator 32 . The example interruption 70 includes two ribs 72 extending radially from the exterior surface 68 positioned axially between the generator 32 . The ribs 72 are axially spaced from each other, and each of the ribs 72 extends circumferentially and continuously about the entire axis 54 . [0039] In one specific example, the diameter of the second drive shaft 56 is about 0.65 inches (1.65 centimeters), and the ribs 72 each extend more than about 0.005 inches (0.127 millimeters) from the exterior surface 68 . In some examples, the ribs extend about 0.039 inches (1 millimeter) from the exterior surface 68 . [0040] The ribs 72 may be considered slinger rings. Other examples of the interruption 70 may include other numbers of ribs or other features. [0041] The example interruption 70 redirects fluid flowing from the hydraulic pump 38 to the generator 32 when the second drive shaft 56 is rotated. In some examples, the second drive shaft 56 rotates at about 12,000 rotations per minute. As the fluid flow moves over the interruption 70 , the fluid is moved radially outward, which causes the fluid to separate from the drive shaft 56 and to move radially outward due to the increased centrifugal force. The fluid moves from the second drive shaft 56 into a cavity 74 that extends about the axis 54 . One of the ribs 72 a is located radially inside of a pump ring 82 to direct leakage away from shaft 56 at the first opportunity. Most of the leakage will encounter the inner diameter of the pump ring 82 , and gravity will cause it to flow from there to drain passage 78 (since the generator shaft 56 is not quite vertical when deployed). [0042] Fluid that gets by the rib 72 a will encounter the rib 72 b , which will expel the fluid into cavity 74 . Fluid that somehow passes both ribs 72 a and 72 b and enters the region between the rib 72 b and the splined portion of the shaft 56 will be centrifugally expelled to the inner diameter of the shaft 52 , where it can then be flung out into cavity 74 . [0043] The generator 18 is constructed from materials that can withstand the occasional splash of hydraulic fluid. But full immersion or sustained contact would be undesirable. The fluid exclusion features described are designed to prevent this. An air gap exists between the second drive shaft 56 and a shield 80 to avoid seal drag or seal friction heating with unreliable lubrication that could occur on a rapidly rotating shaft. [0044] The example cavity 74 is an annular cavity in this example. A portion of the cavity 74 is provided by a housing 76 of the hydraulic pump 38 , and another portion of the cavity 74 is provided by the generator housing 24 . A conduit 78 drains the fluid from the cavity 74 into an ecology bottle (not shown) that can be removed from the RAT 10 . [0045] The example generator 18 includes a shield 80 that is integral with a bearing liner of the RAT 10 . Fluid that lands on the shield 80 tends to move toward the conduit 78 due to gravity. The shield 80 has a raised flange on the inside of the shield 80 that keeps fluid from dripping into bearing areas 86 of the generator 18 . Gravity keeps fluid from travelling over the flange. The flange is located axially away from an end 84 of the drive shaft 52 so fluid from inside the drive shaft 52 can spray harmlessly past the gap to the bearing areas 86 . [0046] In some examples, an O-ring (not shown) may surround the second drive shaft 56 between the hydraulic pump 20 and the generator 18 . [0047] Features of the disclosed examples include providing inline power generation with a single gearbox 16 that drives both the generator 18 and the hydraulic pump 20 while limiting leakage flow from the hydraulic pump 20 to the generator. [0048] The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims.
An exemplary method of controlling fluid flow in a ram air turbine assembly, includes redirecting flow moving in an axial direction against the surface of a drive shaft to flow moving in a radial direction away from the drive shaft to limit flow of the fluid from a hydraulic pump to a generator.
Provide a concise summary of the essential information conveyed in the given context.
[ "CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a division of U.S. patent application Ser.", "No. 13/430,925 filed Mar. 27, 2012.", "BACKGROUND [0002] This disclosure relates to ram air turbines utilized to provide emergency power for an aircraft.", "More particularly, this disclosure relates to controlling fluid within a ram air turbine that supplies both electric and hydraulic power to an aircraft.", "[0003] A ram air turbine is used to generate supplemental power in an aircraft by extracting power from an air stream along the exterior of the aircraft during flight.", "The ram air turbine includes a turbine that drives an electric motor or hydraulic pump.", "In operation, the turbine is moved from a stowed position within the aircraft to a position that provides clearance for blades of the turbine and the aircraft.", "The turbine is mounted at the end of a strut and drives a turbine drive shaft that in turn drives the electric motor or hydraulic pump.", "Hydraulic fluid from the hydraulic pump may be damaging to generator components.", "SUMMARY [0004] A method of controlling fluid flow in a ram air turbine assembly according to an exemplary aspect of the present disclosure includes, among other things, redirecting flow moving in an axial direction against the surface of a drive shaft to flow moving in a radial direction away from the drive shaft to limit flow of the fluid from a hydraulic pump to a generator.", "[0005] In a further non-limiting embodiment of the foregoing method, the method includes using a radially extending feature of the drive shaft to initiate the redirecting.", "[0006] In a further non-limiting embodiment of any of the foregoing methods, the method includes driving the hydraulic pump and the generator using the drive shaft.", "[0007] In a further non-limiting embodiment of any of the foregoing methods, the method includes rotating a turbine of a ram air turbine to rotate the drive shaft.", "[0008] In a further non-limiting embodiment of any of the foregoing methods, the fluid is a hydraulic fluid.", "[0009] In a further non-limiting embodiment of any of the foregoing methods, the method includes moving a strut from a stowed position to a deployed position, and redirecting after the deploying.", "[0010] In a further non-limiting embodiment of any of the foregoing methods, the method includes rotating the drive shaft about a drive shaft axis to directly drive the hydraulic pump and the generator when the strut is in the deployed position.", "[0011] In a further non-limiting embodiment of any of the foregoing methods, the method includes supporting a turbine within the strut, the strut connected to a turbine shaft that rotates about a turbine shaft axis transverse to the drive shaft axis.", "[0012] In a further non-limiting embodiment of any of the foregoing methods, the method includes redirecting flow moving in the axial direction to flow moving in the radial direction into an annular cavity.", "[0013] In a further non-limiting embodiment of any of the foregoing methods, the method includes holding at least a portion of both the hydraulic pump and the generator within a housing assembly and providing the annular cavity within the housing assembly.", "[0014] In a further non-limiting embodiment of any of the foregoing methods, the method includes draining the fluid from the annular cavity using a conduit.", "[0015] In a further non-limiting embodiment of any of the foregoing methods, the drive shaft, the hydraulic pump, and the generator are axially aligned.", "[0016] In a further non-limiting embodiment of any of the foregoing methods, the generator is axially closer to the turbine than the hydraulic pump.", "[0017] In a further non-limiting embodiment of any of the foregoing methods, the method includes redirecting using an interruption in the drive shaft.", "[0018] In a further non-limiting embodiment of any of the foregoing methods, the interruption extends circumferentially and continuously about the entire axis.", "[0019] In a further non-limiting embodiment of any of the foregoing methods, the interruption comprises a first rib extending radially from the drive shaft and a second rib extending radially from the drive shaft, the first rib axially spaced from the second rib.", "[0020] A method of controlling flow in a ram air turbine according to another exemplary aspect of the present disclosure includes, among other things, rotating a turbine to rotate a turbine shaft about a turbine shaft axis when a ram air turbine is in a deployed position, rotating a drive shaft about a turbine shaft axis with the turbine shaft, the turbine shaft rotating about a turbine shaft axis that is transverse to the drive shaft axis, driving a hydraulic pump and a generator with the drive shaft, and redirecting a fluid flowing from the hydraulic pump to a generator into an cavity provided by a housing of the ram air turbine.", "[0021] In a further non-limiting embodiment of the foregoing method, the cavity is an annular cavity.", "[0022] In a further non-limiting embodiment of any of the foregoing methods, the method includes redirecting using an interruption in the drive shaft.", "[0023] In a further non-limiting embodiment of any of the foregoing methods, the method includes holding the hydraulic pump, the generator, or both within the housing.", "DESCRIPTION OF THE FIGURES [0024] The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description.", "The figures that accompany the detailed description can be briefly described as follows: [0025] FIG. 1 is a schematic view of an example ram air turbine including a generator and a hydraulic pump.", "[0026] FIG. 2 is a sectional view of the FIG. 1 ram air turbine.", "[0027] FIG. 3 is a close-up sectional view of an interface between the generator and the hydraulic pump of the FIG. 1 ram air turbine.", "DETAILED DESCRIPTION [0028] Referring to FIGS. 1 and 2 , an example ram air turbine assembly (RAT) 10 is mounted to an airframe 12 and is deployable to provide both electric power and hydraulic pressure.", "The example RAT 10 includes a turbine 14 that rotates responsive to air flow along the outside of the airframe 12 .", "The turbine 14 is supported at the end of strut 22 attached to a generator housing 24 .", "The generator housing 24 is mounted for rotation to the airframe 12 with a swivel post 28 .", "[0029] A generator 32 disposed within the generator housing 24 is coupled to a hydraulic pump 38 .", "The generator 32 generates electric power that can be supplied to an aircraft system such as is schematically indicated at 40 .", "The hydraulic pump 38 receives fluid from a fluid supply 44 and pumps the fluid to various systems indicated at 42 that utilize pressurized fluid for operation.", "[0030] The turbine 14 rotates to drive a turbine shaft 46 about an axis 48 .", "The turbine shaft 46 drives a gearbox 50 .", "The example gearbox 50 is disposed aft of the turbine 14 and along the axis 48 of rotation of the turbine 14 and turbine shaft 46 .", "The example gearbox 50 drives a drive shaft 52 that rotates about an axis 54 that is transverse to the axis 48 .", "The drive shaft 52 extends from the gearbox 16 through the strut 22 to the generator 32 .", "The drive shaft 52 is coupled to drive the generator 32 at a desired speed.", "[0031] The example gearbox 50 includes gears that provide a desired ratio of rotational speed between the turbine shaft 46 and the drive shaft 52 .", "In this example, the drive shaft 52 is rotated at a greater speed than the turbine shaft 46 .", "The gearbox 50 can be configured to provide any desired speed ratio relative to rotation of the turbine 14 .", "[0032] The speed at which the drive shaft 52 is rotated is determined to provide the desired rotational speed required to drive the generator 32 and produce a desired amount of electrical energy at the desired frequency.", "The electrical energy produced by the generator 32 is then transmitted to the aircraft system schematically indicated at 40 .", "[0033] A second drive shaft 56 couples the hydraulic pump 38 in rotation with the generator 32 such that the hydraulic pump 38 rotates at the same speed as the generator 32 .", "As the hydraulic pump 38 and the generator 32 are coupled to rotate together, the hydraulic pump 20 communicates pressurized fluid to the aircraft systems 40 at the same time as the generator 18 produces electric power.", "[0034] The generator 18 is supported within the generator housing 24 at an end distal from the turbine 14 .", "The generator housing 24 includes a mounting bracket 60 and an integral swivel bracket 58 .", "The mounting bracket 60 attaches to an actuator 62 .", "The actuator 62 drives movement of the RAT 10 between a stowed position within the airframe 12 and the deployed position schematically shown in FIG. 1 .", "[0035] The swivel bracket 58 mounts to the swivel post 28 to support the RAT 10 .", "The strut 22 is attached to the generator housing 24 and therefore moves with the pivoting movement of the generator housing 24 .", "The hydraulic pump 20 is mounted to the generator housing 24 and therefore also rotates with the generator housing 24 during movement to the deployed position.", "[0036] Referring to FIG. 3 , the second drive shaft 56 is rotated by the main drive shaft 52 through a spline connection 66 .", "The second drive shaft 56 couples rotation of rotors within the generator 32 with rotation of the hydraulic pump 38 .", "In other examples, the second drive shaft 56 is not a separate shaft but is instead a continuation of the drive shaft 52 .", "[0037] The hydraulic pump 38 is mostly vertically above the generator 32 when the RAT 10 is deployed.", "When deployed, some of the face seal leakage flows from the hydraulic pump 38 against an exterior surface 68 of the second drive shaft 56 , and toward the generator 32 .", "The example fluid is hydraulic fluid such as Skydrol® or some other type of phosphate ester hydraulic fluid.", "The fluid can damage components of the generator 32 as is known.", "When not deployed, the fluid is not in a position to flow downward along the exterior surface 68 .", "[0038] The example second drive shaft 56 includes an interruption 70 that limits flow of fluid from the hydraulic pump 38 to the generator 32 .", "The interruption 70 is axially between the hydraulic pump 38 and the generator 32 .", "The example interruption 70 includes two ribs 72 extending radially from the exterior surface 68 positioned axially between the generator 32 .", "The ribs 72 are axially spaced from each other, and each of the ribs 72 extends circumferentially and continuously about the entire axis 54 .", "[0039] In one specific example, the diameter of the second drive shaft 56 is about 0.65 inches (1.65 centimeters), and the ribs 72 each extend more than about 0.005 inches (0.127 millimeters) from the exterior surface 68 .", "In some examples, the ribs extend about 0.039 inches (1 millimeter) from the exterior surface 68 .", "[0040] The ribs 72 may be considered slinger rings.", "Other examples of the interruption 70 may include other numbers of ribs or other features.", "[0041] The example interruption 70 redirects fluid flowing from the hydraulic pump 38 to the generator 32 when the second drive shaft 56 is rotated.", "In some examples, the second drive shaft 56 rotates at about 12,000 rotations per minute.", "As the fluid flow moves over the interruption 70 , the fluid is moved radially outward, which causes the fluid to separate from the drive shaft 56 and to move radially outward due to the increased centrifugal force.", "The fluid moves from the second drive shaft 56 into a cavity 74 that extends about the axis 54 .", "One of the ribs 72 a is located radially inside of a pump ring 82 to direct leakage away from shaft 56 at the first opportunity.", "Most of the leakage will encounter the inner diameter of the pump ring 82 , and gravity will cause it to flow from there to drain passage 78 (since the generator shaft 56 is not quite vertical when deployed).", "[0042] Fluid that gets by the rib 72 a will encounter the rib 72 b , which will expel the fluid into cavity 74 .", "Fluid that somehow passes both ribs 72 a and 72 b and enters the region between the rib 72 b and the splined portion of the shaft 56 will be centrifugally expelled to the inner diameter of the shaft 52 , where it can then be flung out into cavity 74 .", "[0043] The generator 18 is constructed from materials that can withstand the occasional splash of hydraulic fluid.", "But full immersion or sustained contact would be undesirable.", "The fluid exclusion features described are designed to prevent this.", "An air gap exists between the second drive shaft 56 and a shield 80 to avoid seal drag or seal friction heating with unreliable lubrication that could occur on a rapidly rotating shaft.", "[0044] The example cavity 74 is an annular cavity in this example.", "A portion of the cavity 74 is provided by a housing 76 of the hydraulic pump 38 , and another portion of the cavity 74 is provided by the generator housing 24 .", "A conduit 78 drains the fluid from the cavity 74 into an ecology bottle (not shown) that can be removed from the RAT 10 .", "[0045] The example generator 18 includes a shield 80 that is integral with a bearing liner of the RAT 10 .", "Fluid that lands on the shield 80 tends to move toward the conduit 78 due to gravity.", "The shield 80 has a raised flange on the inside of the shield 80 that keeps fluid from dripping into bearing areas 86 of the generator 18 .", "Gravity keeps fluid from travelling over the flange.", "The flange is located axially away from an end 84 of the drive shaft 52 so fluid from inside the drive shaft 52 can spray harmlessly past the gap to the bearing areas 86 .", "[0046] In some examples, an O-ring (not shown) may surround the second drive shaft 56 between the hydraulic pump 20 and the generator 18 .", "[0047] Features of the disclosed examples include providing inline power generation with a single gearbox 16 that drives both the generator 18 and the hydraulic pump 20 while limiting leakage flow from the hydraulic pump 20 to the generator.", "[0048] The preceding description is exemplary rather than limiting in nature.", "Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure.", "Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims." ]
BACKGROUND OF THE INVENTION This invention relates to treatment of gaseous waste containing sulfur, or nitrogen compounds and more particularly relates to biological treatment systems for such gaseous waste. It has been known that retention ponds could be built for holding aqueous waste materials containing undesirable materials and that to some extent such materials could be biologically metabolized and degraded by organisms within the pond. Such ponds have, however, been difficult to manage in that the undesirable materials (pollutants ) could overwhelm many desirable life forms within the pond thus causing it to become biologically unstable. Additionally, metabolic products build up which are toxic to the metabolizing organisms. Removal of such toxic products was difficult and expensive and sometimes not even possible. Furthermore, to maintain a viable population of such organisms, nutrients often had to be supplied to the pond, especially when commonly occurring organisms were depleted or destroyed by toxic pollutants or metabolic products. It has further been known to use bacteria as the organisms for metabolizing the undesirable waste materials. For example bacteria of the genus Thiobacillus is known to convert certain undesirable liquid and gaseous sulfur containing compounds such as hydrogen sulfide, mercaptans, inorganic sulfides, sulfites and carbon disulfide into more biologically inert metabolic by-product compounds containing SO 4 = . Unfortunately, most such SO 4 = containing compounds are usually in the form of sulfuric acid which rapidly becomes toxic and must be neutralizer. Examples of such Thiobacillus bacteria include Thiobacillus thiooxidans, Thiobacillus ferrooxidans, Thiobacillus thioparus, Thiobacillus denitrificans, Thiobacillus neapolitanus, Thiobacillus tepidarius, Thiobacillus versutus and Thiobacillus intermedius. The bacteria Thiobacillus denitrificans is also known to metabolize undesirable nitrogen containing compounds. Other bacteria are known which will metabolize alcohols, such as methanol and ethanol, methane, ketones, aldehydes, esters, ethers and carboxylic acids such as acetic and formic acids. It has also been known to attempt to neutralize metabolically produced acids by throwing lime or ground limestone into a pond. Such an approach is messy, expensive and poses other problems associated with turbidity and floating of powdered material and usually does very little to offset the toxic effects of introduced pollutants. Attempts have been made to biologically treat aqueous not gaseous effluents within columns containing limestone for purposes of neutralization. Nutrients must be added to and maintained within the waste stream in proper concentration which is exceedingly difficult. When undesirable microbial colonies become established they can overpower desirable organisms or shield the limestone from contact with acid within water passing through the column. When desirable microorganisms are replaced by other undesirable organisms or killed by improper nutrient balance or when the limestone must be replaced, desirable colonies must again be reestablished. This is often time consuming and difficult. BRIEF DESCRIPTION OF THE DRAWING The drawing shows a schematic view of a system in accordance with the present invention. BRIEF DESCRIPTION OF THE INVENTION The invention comprises a biological treatment system for removal of gaseous waste materials in a gaseous waste stream. The system comprises a column containing bacteria which break down said gaseous materials; a pond in series with the column containing life forms in addition to the bacteria, which life forms provide essential nutrients for the bacteria; a treatment bed containing a reaction medium for removing undesirable biological metabolic by-products from the action of said bacteria upon the gaseous waste materials; a fluid distribution means for circulating water between the pond, column and bed and a means for delivering the gaseous waste materials through the column before such waste materials reach the pond. DETAILED DESCRIPTION OF THE INVENTION "Biological treatment", as used herein, means to be ingested or eaten by a living organism and converted or metabolized by the organism to a more environmentally friendly or manageable substance. "Waste material" means a biologically treatable material which is environmentally unfriendly and not in a form for practical use for any purpose. "Environmentally unfriendly" means an undesirable organic or inorganic compound which in sufficient concentration may be toxic, noxious or carcinogenic to plant or animal life. "Sulfur or nitrogen containing component" means a nitrogen or sulfur containing waste material. Examples of such compounds are hydrogen sulfide, carbon disulfide, sulfur dioxide, nitrous oxide, nitrogen dioxide, nitrogen pentoxide, and organic compounds which contain a --SO 3 , --NO 2 , --SR, or --NR 2 group where R is hydrogen or a carbon containing radical. Examples of such groups are mercapto, thioether and amino groups. "Gaseous waste material" means a waste material which is in a gaseous or vapor phase at ambient conditions. Examples of such gaseous waste materials are carbon disulfide, hydrogen sulfide, nitrous oxide, nitric oxide, nitrogen dioxide, ammonia, sulfur dioxide, methane, methanol vapor, ethanol vapor, formaldehyde vapor, formic acid vapor, acetic acid vapor, sulfur trioxide and methyl mercaptan. Specific concentrations of such gaseous waste material may vary, e.g. from less than about 20 ppm to above about 5000 ppm. CS 2 or H 2 S gaseous waste material is usually from about 20 to about 5000 ppm in air. "Column" as used herein means an elongated container containing a material (e.g. limestone or porous beads) which will act as a substrate for a microorganism which will metabolize a gaseous waste material, such as a sulfur or nitrogen containing component, as previously described. The column, in general, is designed to permit one or more fluids to flow through it. The column substrate material is kept damp by a liquid fluid, but is not immersed in liquid. When two fluids flow through the column, they may flow concurrent or counter current to each other. Usually pond water flows at a slow rate downwardly through the column while an air stream containing an environmentally undesirable sulfur or nitrogen containing gaseous component flows either upwardly or downwardly through the column. "Pond", as used herein means a body of water having a depth of at least eight inches and a surface which is open to the air. "Microorganism" as used herein means an organism, normally unicellular, not visible to the unaided eye. Microorganisms suitable for use in accordance with the present invention for metabolizing gaseous waste materials, e.g., sulfur or nitrogen containing components, include bacteria, algae, yeasts and molds. The most commonly used microorganisms for that purpose are bacteria. "Additional life forms" means life forms in addition to the microorganisms which metabolize introduced undesirable waste materials, such as sulfur or nitrogen containing components. Such additional life forms may develop nutrients for the metabolizing microorganisms or may further metabolize by-products from the metabolizing microorganisms. Such additional life forms are aquatic or semi aquatic and include bacteria, protists, algae, fungi including yeasts and molds, higher plant life including bryophytes, pteridophytes and spermatophytes, polyps, hydra, mollusks, various worms, arthropods including crustaceans, including fairy shrimps and crawfish, insects, myriapods and spiders, fish, amphibians and reptiles. "Bacteria" as used herein means one celled, prokaryote, chlorophyll free microorganisms which reproduce by simple cell division including the cocci, bacilli and spirilla forms thereof. Especially suitable for metabolic processes used in the present invention are the thiobacillus bacteria as previously described. "Reaction medium" as used herein means a chemical material suitable for reducing or eliminating toxic effects of metabolic by-products. Such by-products are usually acidic in nature, e.g. sulfuric acid or nitric acid. A preferred reaction medium for neutralizing acidic by-products is calcium carbonate, usually in the form of limestone. Reaction media which can neutralize ammonium hydroxide include acidic salts such as magnesium sulfate, aluminum sulfate, aluminum chloride, zinc chloride, magnesium chloride or zinc sulfate, and mineral acids such as sulfuric acid, phosphoric acid or hydrochloric acid or organic acids such as acetic acid. The fluid distribution means is usually a pump which removes water from the pond and sprays it on the column medium at the top of the column to keep the medium moist and provide nutrients. The means for delivering pollutants through the column is a fan or gas pump for causing flow of gas through the column. All pollutants are not necessarily removed from one pass through the column. Some of the pollutants may be absorbed in the water within the column and circulated to the pond where further metabolism occurs. In view of the discussion herein the advantages of the system become apparent. The highest concentration of pollutants initially pass through the column containing microorganisms which are not only resistant to the pollutants but feed upon them. The pond provides nutrients and keeps them in balance without significant human intervention and provides a reservoir for further metabolism of pollutants absorbed in recirculating water. In the event that the column must be shut down, recovery is rapid because the pond provides a reservoir of desirable microorganisms. The neutralizing bed may be separate or integral with the column and may be easily serviced without significant down time due to fast recovery as previously described. The following examples serve to illustrate and not limit the present invention: EXAMPLE 1 As shown in the drawing, a five foot long ten inch diameter fiberglass reinforced column 10, such as used in aquaculture, was filled with small limestone pieces 12 after sieving out fines through a 1/2 inch screen. The limestone provided calcium and magnesium carbonates for neutralization of H 2 SO 4 produced in the process and thus maintains an essentially neutral pH. The limestone also provides carbon for bacterial reproduction and inorganic micronutrients needed to support healthy bacterial growth. The column was covered with a fiberglass plate 14 through which two stainless steel pipes 16 and 18 were inserted for gas and water supply. Bottom outlet pipe 20 was attached to the bottom 24 of column 10. The column 10 was placed on a raised platform, not shown, for accommodation of bottom pipe 20 and for gravity flow of liquid effluent into subsequent tanks designated as T-1, T-2 and T-3 filled with deionized water which were exposed to sunlight. Alternatively a pump can be used to transfer water. Tank T-2 acted as a pond. Liquid outlet pipe 20 from the column was connected to tank T-1 near its top. The tanks all had dimensions of 24 inches long by 17 inches wide by 19 inches deep. An outlet 26 near the bottom of T-1 flowed into tank T-2. An outlet 28 from T-2 flowed into T-3 from where water was pumped back to the top of column 10 by means of pump 29, conduit 30 and nozzle 32. Several live fish 34 variously selected from goldfish, tilapia or catfish were introduced into tank T-2 and provided organic nutrients for the bacteria, especially organic nitrogen. Effluent air from a viscose plant containing CS 2 and H 2 S gases was introduced into the top of the column 10 through inlet 16 and out through an inverted "J" fitting 36 at bottom 24 to prevent water from entering chromatograph line 38. Both the influent and effluent gases were connected by lines 38 and 39 through an automatic gas sampling device to a gas chromatograph for monitoring of concentration of CS 2 and H 2 S. The limestone containing column 10 was inoculated with filtered mud slurries from the bank of a small creek near a viscose plant, from a lagoon bank where plant effluents were treated, from a sulfur spring fed channel at French Lick, Ind., and with cultured thiobacillus bacteria from mud samples obtained near a viscose plant. Within a month destruction efficiency for about 20 parts per million (ppm) H 2 S and about 20 ppm CS 2 , went to 100% for H 2 S and 90-95% for CS 2 . The system was also run with plants 40 and fish 34 in T-1 and T-3. For example bitter melon, jalapeno pepper, and Malabar lettuce were grown in floating type planters 42. In all cases the system ran with almost no intervention. No artificial nutrients were provided for the bacteria and no neutralizing caustic was introduced. Initially the fish were fed with fish food which was stopped when the tanks developed algae growth. EXAMPLE 2 The above example was repeated on a larger scale using a 30 inch by 40 inch high limestone bed and 47×25×18 inch tanks. Air flow was increased to 70 to 80 liters per minute without adversely affecting the destruction efficiency of the H 2 S and CS 2 . When sulfate concentration, usually in the form of magnesium sulfate, became too high a portion of the water was replaced and the system continued to efficiently run with essentially no interruption. The system was run for several months with no problems.
A biological treatment system for removal of gaseous waste materials. The system comprises a column containing microorganisms which break down components of the waste materials; a pond in series with the column containing life forms in addition to the microorganisms in the column, which life forms provide essential nutrients for the microorganisms in the column; a treatment bed containing a reaction medium for removing undesirable biological metabolic by-products from the action of said microorganisms upon the gaseous waste materials; a fluid distribution means for circulating water between the pond, column and bed and a means for delivering gaseous waste materials through the column before such gaseous waste materials reach the pond.
Provide a concise summary of the essential information conveyed in the context.
[ "BACKGROUND OF THE INVENTION This invention relates to treatment of gaseous waste containing sulfur, or nitrogen compounds and more particularly relates to biological treatment systems for such gaseous waste.", "It has been known that retention ponds could be built for holding aqueous waste materials containing undesirable materials and that to some extent such materials could be biologically metabolized and degraded by organisms within the pond.", "Such ponds have, however, been difficult to manage in that the undesirable materials (pollutants ) could overwhelm many desirable life forms within the pond thus causing it to become biologically unstable.", "Additionally, metabolic products build up which are toxic to the metabolizing organisms.", "Removal of such toxic products was difficult and expensive and sometimes not even possible.", "Furthermore, to maintain a viable population of such organisms, nutrients often had to be supplied to the pond, especially when commonly occurring organisms were depleted or destroyed by toxic pollutants or metabolic products.", "It has further been known to use bacteria as the organisms for metabolizing the undesirable waste materials.", "For example bacteria of the genus Thiobacillus is known to convert certain undesirable liquid and gaseous sulfur containing compounds such as hydrogen sulfide, mercaptans, inorganic sulfides, sulfites and carbon disulfide into more biologically inert metabolic by-product compounds containing SO 4 = .", "Unfortunately, most such SO 4 = containing compounds are usually in the form of sulfuric acid which rapidly becomes toxic and must be neutralizer.", "Examples of such Thiobacillus bacteria include Thiobacillus thiooxidans, Thiobacillus ferrooxidans, Thiobacillus thioparus, Thiobacillus denitrificans, Thiobacillus neapolitanus, Thiobacillus tepidarius, Thiobacillus versutus and Thiobacillus intermedius.", "The bacteria Thiobacillus denitrificans is also known to metabolize undesirable nitrogen containing compounds.", "Other bacteria are known which will metabolize alcohols, such as methanol and ethanol, methane, ketones, aldehydes, esters, ethers and carboxylic acids such as acetic and formic acids.", "It has also been known to attempt to neutralize metabolically produced acids by throwing lime or ground limestone into a pond.", "Such an approach is messy, expensive and poses other problems associated with turbidity and floating of powdered material and usually does very little to offset the toxic effects of introduced pollutants.", "Attempts have been made to biologically treat aqueous not gaseous effluents within columns containing limestone for purposes of neutralization.", "Nutrients must be added to and maintained within the waste stream in proper concentration which is exceedingly difficult.", "When undesirable microbial colonies become established they can overpower desirable organisms or shield the limestone from contact with acid within water passing through the column.", "When desirable microorganisms are replaced by other undesirable organisms or killed by improper nutrient balance or when the limestone must be replaced, desirable colonies must again be reestablished.", "This is often time consuming and difficult.", "BRIEF DESCRIPTION OF THE DRAWING The drawing shows a schematic view of a system in accordance with the present invention.", "BRIEF DESCRIPTION OF THE INVENTION The invention comprises a biological treatment system for removal of gaseous waste materials in a gaseous waste stream.", "The system comprises a column containing bacteria which break down said gaseous materials;", "a pond in series with the column containing life forms in addition to the bacteria, which life forms provide essential nutrients for the bacteria;", "a treatment bed containing a reaction medium for removing undesirable biological metabolic by-products from the action of said bacteria upon the gaseous waste materials;", "a fluid distribution means for circulating water between the pond, column and bed and a means for delivering the gaseous waste materials through the column before such waste materials reach the pond.", "DETAILED DESCRIPTION OF THE INVENTION "Biological treatment", as used herein, means to be ingested or eaten by a living organism and converted or metabolized by the organism to a more environmentally friendly or manageable substance.", ""Waste material"", "means a biologically treatable material which is environmentally unfriendly and not in a form for practical use for any purpose.", ""Environmentally unfriendly"", "means an undesirable organic or inorganic compound which in sufficient concentration may be toxic, noxious or carcinogenic to plant or animal life.", ""Sulfur or nitrogen containing component"", "means a nitrogen or sulfur containing waste material.", "Examples of such compounds are hydrogen sulfide, carbon disulfide, sulfur dioxide, nitrous oxide, nitrogen dioxide, nitrogen pentoxide, and organic compounds which contain a --SO 3 , --NO 2 , --SR, or --NR 2 group where R is hydrogen or a carbon containing radical.", "Examples of such groups are mercapto, thioether and amino groups.", ""Gaseous waste material"", "means a waste material which is in a gaseous or vapor phase at ambient conditions.", "Examples of such gaseous waste materials are carbon disulfide, hydrogen sulfide, nitrous oxide, nitric oxide, nitrogen dioxide, ammonia, sulfur dioxide, methane, methanol vapor, ethanol vapor, formaldehyde vapor, formic acid vapor, acetic acid vapor, sulfur trioxide and methyl mercaptan.", "Specific concentrations of such gaseous waste material may vary, e.g. from less than about 20 ppm to above about 5000 ppm.", "CS 2 or H 2 S gaseous waste material is usually from about 20 to about 5000 ppm in air.", ""Column"", "as used herein means an elongated container containing a material (e.g. limestone or porous beads) which will act as a substrate for a microorganism which will metabolize a gaseous waste material, such as a sulfur or nitrogen containing component, as previously described.", "The column, in general, is designed to permit one or more fluids to flow through it.", "The column substrate material is kept damp by a liquid fluid, but is not immersed in liquid.", "When two fluids flow through the column, they may flow concurrent or counter current to each other.", "Usually pond water flows at a slow rate downwardly through the column while an air stream containing an environmentally undesirable sulfur or nitrogen containing gaseous component flows either upwardly or downwardly through the column.", ""Pond", as used herein means a body of water having a depth of at least eight inches and a surface which is open to the air.", ""Microorganism"", "as used herein means an organism, normally unicellular, not visible to the unaided eye.", "Microorganisms suitable for use in accordance with the present invention for metabolizing gaseous waste materials, e.g., sulfur or nitrogen containing components, include bacteria, algae, yeasts and molds.", "The most commonly used microorganisms for that purpose are bacteria.", ""Additional life forms"", "means life forms in addition to the microorganisms which metabolize introduced undesirable waste materials, such as sulfur or nitrogen containing components.", "Such additional life forms may develop nutrients for the metabolizing microorganisms or may further metabolize by-products from the metabolizing microorganisms.", "Such additional life forms are aquatic or semi aquatic and include bacteria, protists, algae, fungi including yeasts and molds, higher plant life including bryophytes, pteridophytes and spermatophytes, polyps, hydra, mollusks, various worms, arthropods including crustaceans, including fairy shrimps and crawfish, insects, myriapods and spiders, fish, amphibians and reptiles.", ""Bacteria"", "as used herein means one celled, prokaryote, chlorophyll free microorganisms which reproduce by simple cell division including the cocci, bacilli and spirilla forms thereof.", "Especially suitable for metabolic processes used in the present invention are the thiobacillus bacteria as previously described.", ""Reaction medium"", "as used herein means a chemical material suitable for reducing or eliminating toxic effects of metabolic by-products.", "Such by-products are usually acidic in nature, e.g. sulfuric acid or nitric acid.", "A preferred reaction medium for neutralizing acidic by-products is calcium carbonate, usually in the form of limestone.", "Reaction media which can neutralize ammonium hydroxide include acidic salts such as magnesium sulfate, aluminum sulfate, aluminum chloride, zinc chloride, magnesium chloride or zinc sulfate, and mineral acids such as sulfuric acid, phosphoric acid or hydrochloric acid or organic acids such as acetic acid.", "The fluid distribution means is usually a pump which removes water from the pond and sprays it on the column medium at the top of the column to keep the medium moist and provide nutrients.", "The means for delivering pollutants through the column is a fan or gas pump for causing flow of gas through the column.", "All pollutants are not necessarily removed from one pass through the column.", "Some of the pollutants may be absorbed in the water within the column and circulated to the pond where further metabolism occurs.", "In view of the discussion herein the advantages of the system become apparent.", "The highest concentration of pollutants initially pass through the column containing microorganisms which are not only resistant to the pollutants but feed upon them.", "The pond provides nutrients and keeps them in balance without significant human intervention and provides a reservoir for further metabolism of pollutants absorbed in recirculating water.", "In the event that the column must be shut down, recovery is rapid because the pond provides a reservoir of desirable microorganisms.", "The neutralizing bed may be separate or integral with the column and may be easily serviced without significant down time due to fast recovery as previously described.", "The following examples serve to illustrate and not limit the present invention: EXAMPLE 1 As shown in the drawing, a five foot long ten inch diameter fiberglass reinforced column 10, such as used in aquaculture, was filled with small limestone pieces 12 after sieving out fines through a 1/2 inch screen.", "The limestone provided calcium and magnesium carbonates for neutralization of H 2 SO 4 produced in the process and thus maintains an essentially neutral pH.", "The limestone also provides carbon for bacterial reproduction and inorganic micronutrients needed to support healthy bacterial growth.", "The column was covered with a fiberglass plate 14 through which two stainless steel pipes 16 and 18 were inserted for gas and water supply.", "Bottom outlet pipe 20 was attached to the bottom 24 of column 10.", "The column 10 was placed on a raised platform, not shown, for accommodation of bottom pipe 20 and for gravity flow of liquid effluent into subsequent tanks designated as T-1, T-2 and T-3 filled with deionized water which were exposed to sunlight.", "Alternatively a pump can be used to transfer water.", "Tank T-2 acted as a pond.", "Liquid outlet pipe 20 from the column was connected to tank T-1 near its top.", "The tanks all had dimensions of 24 inches long by 17 inches wide by 19 inches deep.", "An outlet 26 near the bottom of T-1 flowed into tank T-2.", "An outlet 28 from T-2 flowed into T-3 from where water was pumped back to the top of column 10 by means of pump 29, conduit 30 and nozzle 32.", "Several live fish 34 variously selected from goldfish, tilapia or catfish were introduced into tank T-2 and provided organic nutrients for the bacteria, especially organic nitrogen.", "Effluent air from a viscose plant containing CS 2 and H 2 S gases was introduced into the top of the column 10 through inlet 16 and out through an inverted "J"", "fitting 36 at bottom 24 to prevent water from entering chromatograph line 38.", "Both the influent and effluent gases were connected by lines 38 and 39 through an automatic gas sampling device to a gas chromatograph for monitoring of concentration of CS 2 and H 2 S. The limestone containing column 10 was inoculated with filtered mud slurries from the bank of a small creek near a viscose plant, from a lagoon bank where plant effluents were treated, from a sulfur spring fed channel at French Lick, Ind.", ", and with cultured thiobacillus bacteria from mud samples obtained near a viscose plant.", "Within a month destruction efficiency for about 20 parts per million (ppm) H 2 S and about 20 ppm CS 2 , went to 100% for H 2 S and 90-95% for CS 2 .", "The system was also run with plants 40 and fish 34 in T-1 and T-3.", "For example bitter melon, jalapeno pepper, and Malabar lettuce were grown in floating type planters 42.", "In all cases the system ran with almost no intervention.", "No artificial nutrients were provided for the bacteria and no neutralizing caustic was introduced.", "Initially the fish were fed with fish food which was stopped when the tanks developed algae growth.", "EXAMPLE 2 The above example was repeated on a larger scale using a 30 inch by 40 inch high limestone bed and 47×25×18 inch tanks.", "Air flow was increased to 70 to 80 liters per minute without adversely affecting the destruction efficiency of the H 2 S and CS 2 .", "When sulfate concentration, usually in the form of magnesium sulfate, became too high a portion of the water was replaced and the system continued to efficiently run with essentially no interruption.", "The system was run for several months with no problems." ]
[0001] This application is a continuation application of prior U.S. patent application Ser. No. 11/194,112, filed Jul. 29, 2005 the contents of which is incorporated herein by reference in its entirety. FIELD OF THE INVENTION [0002] The invention relates to a supportive glove for receiving the hand of a wearer for use in athletics. More particularly, the invention relates to a soccer goalkeeper's glove. BACKGROUND [0003] The gloves used by soccer goalkeepers, otherwise known as goalies, typically include a dorsal element and a palmar element, both being fashioned from latex foam, and an element for securing the glove to the goalkeeper's wrist. Although goalkeeper gloves are similar in these respects, there are various modes of goalkeeper glove design that vary with respect to durability, flexibility, and seam placement, thereby affecting the fit and feel of the glove along with the goalkeeper's ability to control the soccer ball. [0004] Goalkeeper glove characteristics are affected by the pattern from which the dorsal and palmar elements are cut and the securing mechanism used to attach the glove to the goalkeeper's wrist. Unlike traditional gloves fashioned from leather, cloth, or a knitted yarn, latex foam is the material of choice among goalkeeper glove designers because of its flexible and protective qualities. The use of latex foam, although having desirable characteristics, affects glove design by necessitating a dorsal and palmar element with multiple seams that may interfere with ball control or reduce durability. [0005] As noted, the pattern from which the dorsal and palmar elements are cut affects glove characteristics. The majority of goalkeeper gloves employ a variety of patterns for the dorsal and palmar elements including: the traditional cut, the gunn cut/rolled finger cut, the rifle cut pattern, or a negative/reuse stitch pattern [0006] In a traditional cut glove 10 , shown in FIGS. 1-2 , a dorsal element 11 and a palmar element 12 are each fashioned from a single section of latex foam material, with only palmar element 12 having an attached thumb region. Supplemental elements (not shown), formed from a flexible material, connect dorsal and palmar elements 11 and 12 in the second through fifth digit regions, thereby creating an interior space for each digit. In addition, the union of dorsal and palmar elements 11 and 12 with the supplemental elements creates a dorsal seam 13 and a palmar seam 14 on the periphery of dorsal and palmar elements 11 and 12 , respectively. The dorsal thumb region includes a separate, flexible supplemental element 15 sewn to the edge of the thumb area of palmar element 12 and to dorsal element 11 . This combination of elements gives traditional cut glove 10 a relatively flat, paddle-like configuration and palmar seam 14 limits the goalkeeper's control of the ball and reduces glove durability. [0007] A gunn cut glove 20 , shown in FIGS. 3-5 , includes a dorsal element 21 and a palmar element 22 that are each fashioned from a single section of latex foam material including regions for the first, second, and fifth digits and dorsal element 21 including regions for the second through fifth digits. The second and fifth digit regions of palmar element 22 have a greater width than corresponding regions of dorsal element 21 . To form the glove regions for the second and fifth digits, the wider palmar regions are flexed to meet the edges of the second and fifth digit regions of dorsal element 21 and then sewn, the flexed material defining a recess for the goalkeeper's digits. The dorsal thumb region is formed from a separate, flexible supplemental element 24 sewn to the edge of the thumb region of palmar element 22 and to dorsal element 21 . [0008] Unlike traditional cut glove 10 , gunn cut glove 20 contains only one seam 25 joining dorsal and palmar elements 21 and 22 in the digit regions due to the lack of supplemental elements. The flexing of the second and fifth digit regions of palmar element 22 and the resulting smooth palmar surface embodies the primary advantage of the gunn cut pattern over the traditional cut pattern. The digit regions of gunn cut glove 20 are rounded and lack seams on the palmar surface that may interfere with ball control. However, the gunn cut glove is more complex and costly to manufacture. Moreover, seam 26 at the base of the third and fourth digits may be uncomfortable and lack durability. [0009] In a rifle cut glove 30 , shown in FIGS. 6-8 , a dorsal element 31 and a palmar element 32 are each formed from a single section of foam material, with palmar element 32 , shown separately in FIG. 8 , including only the first, second, fourth, and fifth digit regions and dorsal element 31 including the second through fifth digit regions. The second digit region of palmar element 32 has a greater width than the corresponding region of dorsal element 31 . A single, separate section 33 of latex foam material, also shown in FIG. 8 , forms the third digit region of palmar element 31 and is sewn to palmar element 31 at the base of the third digit region. Supplemental elements (not shown), formed from a flexible material, connect edges of the dorsal and palmar elements in the third, fourth, and fifth digit regions, thereby creating an interior space for each digit. The union of dorsal and palmar elements 31 and 32 with the supplemental elements creates seams 34 and 35 on the periphery of the dorsal and palmar elements, respectively. To form the glove regions for the second digit, the wider palmar region is flexed to meet the edges of the second digit region of dorsal element 31 and then sewn, the flexed material thereby defining a recess for the goalkeeper's second digit. The dorsal thumb region includes a separate, flexible supplemental element 36 sewn to the edge of the thumb region of palmar element 32 and to dorsal element 31 . [0010] The primary advantage of rifle cut glove 30 lies in the rounded palmar surface of the second digit. Like gunn cut glove 20 , rifle cut glove 30 is more complex and costly to manufacture than traditional cut glove 10 . In addition, seam 37 at the base of the third digit may cause discomfort and represent an area of low durability. [0011] The traditional cut, gunn cut, and the rifle cut pattern goalkeeper gloves have similar wrist securing apparatus which includes a wrist element 50 ( FIGS. 1-7 ) comprising a circumferential band of elastic material. The goalkeeper inserts his/her hand into the circumferential band of material to secure the glove. The circumferential band is sewn to the palmer and dorsal portions of the glove. A strap 52 is attached to wrist element 50 to surround and releasably attach a substantial portion of the circumference of wrist element 50 . However, use of wrist element 50 provides a hindrance to securing the goalkeeper's hand quickly. In addition, the wrist element 50 provides a goalkeeper with adequate flexibility in wrist area of the glove. [0012] Therefore, there is a need in the art for a goalkeeper's glove that overcomes the disadvantages of the prior art gloves and provides a goalkeeper with a glove that gives a greater degree of flexibility and fit, is easy to put on, and exhibits superior ball control characteristics. SUMMARY OF THE INVENTION [0013] The invention relates to an athletic glove for supporting and receiving a hand of a wearer. The glove includes a palmar element and a dorsal element. The palmar element is formed of a first shock-absorbing material and is located to substantially cover a palmar metacarpal area of the wearer's hand and a palmar side of a first digit, a second digit, a third digit, a fourth digit, and a fifth digit of the wearer's hand. The palmar element also has at least one additional section that wraps around a medial or a lateral side of at least one of the second through fifth digits to cover at least a portion of a dorsal side of the digit wrapped by the at least one additional section. The dorsal element is located opposite the palmar element and substantially covers a dorsal metacarpal area of the wearer's hand and at least a portion of the dorsal side of the second digit, the third digit, the fourth digit, and the fifth digit that are not covered by the at least one additional section of the palmar element. [0014] The athletic glove further includes at least one three dimensional finger cap which forms at least a portion of at least one digit of the wearer's hand. The athletic glove also comprises an open wrist feature which allows for a greater degree of adjustability or fit. Furthermore, the open wrist feature allows for better support and the ability to adjust tightness of the glove. The palmar element of the glove includes two wing portions that attach to a stretchable material to secure the glove to the wrist of the wearer. [0015] The advantages and features of novelty characterizing the invention are pointed out with particularity in the appended claims. To gain an improved understanding of the advantages and features of novelty, however, reference may be made to the following descriptive matter and accompanying drawings that describe and illustrate various embodiments and concepts related to the invention. DESCRIPTION OF THE DRAWINGS [0016] FIG. 1 is a plan view of the dorsal side of a traditional cut glove. [0017] FIG. 2 is a plan view of the palmar side of the traditional cut glove. [0018] FIG. 3 is a plan view of the dorsal side of a gunn cut glove. [0019] FIG. 4 is a plan view of the palmar side of the gunn cut glove. [0020] FIG. 5 is an illustration of a first portion of the pattern from which the palmar element of the gunn cut glove is formed. [0021] FIG. 6 is a plan view of the dorsal side of the rifle cut glove. [0022] FIG. 7 is a plan view of the palmar side of the rifle cut glove. [0023] FIG. 8 is an illustration of the patterns from which the palmar element of the rifle cut glove is formed. [0024] FIG. 9 is a plan view of the palmar side of the soccer glove in accordance with an aspect of the invention. [0025] FIG. 10 is an additional plan view of the palmar side of the soccer glove in accordance with an aspect of the invention. [0026] FIG. 11 is a plan view of the dorsal side of the soccer glove in accordance with an aspect of the invention. [0027] FIG. 12 is a plan view of the use of multiple finger caps in accordance with an aspect of the invention. [0028] FIG. 13 illustrates an open wrist portion in accordance with an aspect of the invention. DETAILED DESCRIPTION OF THE INVENTION [0029] Referring to the accompanying figures, a goalkeeper's glove in accordance with various aspects of the invention is disclosed. The figures illustrate only the glove intended for use on the right hand of a wearer. It should be understood by those skilled in the art that a left glove, such glove being a mirror image of the right glove, is included within the scope of the invention. In distinguishing portions of the glove or the hand received by the glove, reference will be made to areas of the hand, including a dorsal, palmar, lateral, and medial side; the five digits; and an area corresponding to the metacarpal bones. Such references are not intended to demarcate precise areas. Rather, they are intended to delineate general areas to aid in discussion. [0030] With reference to FIGS. 9-13 , a goalkeeper's glove according to the present invention is illustrated, wherein the primary elements of a glove 300 include a dorsal element 202 ( FIG. 11 ) and a palmar element 302 ( FIG. 9 ). Dorsal element 202 and palmar element 302 may be formed of any suitable material or combination of suitable materials, including a shock-absorbing, lightweight, foamed, natural latex rubber, ranging in thickness from two to five millimeters, bonded to a lightweight scrim of poly-based cells of approximately two to three millimeters. In addition, a textile layer may be bonded to the interior surface of palmar element 302 to provide enhanced comfort. [0031] FIGS. 9-10 illustrate palmar element 302 in an aspect of the invention. Palmar element 302 may be designed to cover a substantial portion of the palmar area of the wearer's hand. In addition, palmar element 302 may form a continuous section of material. [0032] Palmar element 302 may include a palmar metacarpal area 303 for covering the palmar metacarpal bones and the joints between the metacarpals and phalanges of the second through fifth digits and palmar digit areas 304 a - 304 e for covering the palmar areas of the first through fifth digits, respectively. One skilled in the art will realize that the term first digit conventionally refers to the thumb, the term second digit conventionally refers to the index finger, the term third digit conventionally refers to the middle finger, the term fourth digit refers to the ring finger, and the fifth digit refers to the pinky finger. [0033] Extending from palmar digital areas 304 a , 304 b , and 304 e are additional sections 306 a , 306 b , and 306 e , respectively which are part of the material comprising palmar element 302 . The purpose of additional sections 306 are to wrap around digits, thereby creating a seamless surface that extends from the palmar area, around the sides of the digits, and to the dorsal area. A seamless surface on the medial side of the fifth digit and on lateral sides of the first and second digit create a configuration wherein the digital regions of the glove do not have seams that may interfere with ball control while catching, handling, and throwing. [0034] With respect to the first digit, additional section 306 a may wrap over line 310 a so as to cover the lateral side of the first digit and at least a portion of the dorsal portions of the first digit. Additional section 306 a may be sewn to palmar digital area 304 a and first supplemental element 402 to create a cavity for the first digit. A V-shaped cut 308 a in palmar element 300 may form a flex notch 321 a ( FIG. 10 ) generally at the junction of palmar metacarpal area 302 and first palmar digital area 304 a. [0035] In forming a cavity for receiving the second digit, additional section 306 b may wrap over line 310 b so as to cover the lateral side of the second digit and dorsal portions of the second digit. Additional section 306 b may be sewn to palmar digital area 304 b along the medial side and tip area, and abuts dorsal digital area 204 b ( FIG. 11 ) across the dorsal surface of the second digit. A straight cut 308 b in palmar element 300 may form a flex notch 321 b ( FIG. 10 ) generally at the junction of palmar metacarpal area 302 and palmar digital area 304 b. [0036] Similarly, additional section 306 e may wrap over line 310 e so as to cover the medial side of the fifth digit and dorsal portions of the fifth digit. Additional section 306 e may be sewn to palmar digital area 304 e along the lateral side and tip area and abuts dorsal digital area 204 e ( FIG. 11 ) across the dorsal surface of the fifth digit. A straight cut 308 e in palmar element 300 may form a flex notch 321 e ( FIG. 10 ) generally at the junction of palmar metacarpal area 302 and palmar digital area 304 e. [0037] FIG. 11 illustrates the dorsal side of glove 300 . Dorsal element 202 may include a dorsal metacarpal area 203 for covering the dorsal metacarpal bones and the joints between the metacarpals and phalanges of the first through fifth digits and dorsal digit areas 204 a - 204 e for covering the dorsal areas of the first through fifth digits, respectively. Dorsal element 202 may also comprise a first finger cap 1101 , a second finger cap 1105 , a stretchable material 1110 , and an intermediate material 1115 . In an alternative embodiment, the first digit may include a secondary stretchable material (not shown) that may be used to cover the dorsal area of the first digit. The secondary stretchable material may be sewn to the stretchable material 1110 . [0038] In an aspect of the invention, the union of additional section 306 b with dorsal digital area 204 b is accomplished by sewing additional section 306 b and dorsal digital area 204 b such that the edge of additional section 306 b abuts dorsal digital area 204 b . This configuration forms a flexible joint in the dorsal surface. The union of additional section 306 e with dorsal digital area 204 e is accomplished in a similar manner and creates a second flexible joint. As noted, the seamless surface created by the wrapping of additional sections 306 around digits enhances ball control. The joints in the dorsal surface of the second and fifth digits promote this goal through increased flexibility in these digits. In other aspects of the invention, the possibility of using one or more additional sections to wrap an individual digit are not limited by the particular digit. [0039] Finger cap 1101 and 1105 may be molded from a polymer such as polyethylene, polyurethane, polyamide, polyester, polyolefin, or vinyl. The molding process may produce a three dimensional representation of any of the first through fifth digits or portions thereof. For example, finger cap 1101 along with stretchable material 1110 and intermediate material 1115 may form the dorsal portion of a third digit such as digit area 204 c . Portions of finger cap 1101 may be sewn to stretchable material 1110 and intermediate material 1115 . Finger cap 1101 and intermediate material 1115 may be sewn to palmar digit area 304 c to create a cavity for the third digit. Similarly, finger cap 1105 along with stretchable material 1110 and intermediate material 1115 may be sewn together to form the dorsal portion of a fourth digit. Finger cap 1105 and intermediate material 110 may be sewn to palmar digit area 304 d to create a cavity for the fourth digit. [0040] Those skilled in the art will realize that finger caps may be molded for use on any of the first through fifth digits. For example, FIG. 12 illustrates the use of finger caps 1205 - 1225 on each of the digits of the wearer. Finger caps may provide a goalie's fingers a greater degree of performance and support due to the use of a molded shock-absorbent material. The finger caps may mimic the natural anatomy of a wear's digits due to the molded three dimensional shapes of the finger caps. The molded three dimensional shapes may provide a greater degree of performance. In addition, the use of the finger caps provides the goalie with a greater degree of ball control due to additional finger flexibility given to the various fingers inserted in the finger caps and the reduction of seams on the palmar portion of the glove. In an aspect of the invention, the molded three dimensional finger caps may also include some surface indentations or different size panels representing various areas of a wearer's digits. [0041] Both the stretchable material 1110 and the intermediate material 1115 may comprise an elastic material. The stretchable material 1110 and the intermediate material 1115 may deform in the presence of a tensile force, thereby stretching to accommodate wearers with various finger dimensions. The stretchable material 1110 and the intermediate material 1115 may be any material with the ability to substantially return to an original size and shape following deformation. In addition, the stretchable material 1110 and the intermediate material 1115 may be made from various lightweight, breathable materials. [0042] FIG. 13 illustrates an open wrist portion 1305 in accordance with an aspect of the invention. Referring to FIG. 13 , palmar element 302 includes a first wing portion 1310 and a second wing portion 1315 . The first wing portion 1310 attaches to stretchable material 1110 through the use of a hook and loop fastener system. The second wing portion 1315 overlaps the first wing portion 1110 to form a cylinder that encircles a wrist of the hand of the wearer. The second wing portion 1315 may be connected to the first wing portion 1310 using a hook and loop fastener system. Those skilled in the art will realize that other fastener systems may be utilized to connect the wing portions and the stretchable material 1110 to provide a releasable fastener system. [0043] The open wrist portion 1305 may provide a goalkeeper with adequate flexibility in the wrist area of the glove. In addition, the glove 300 may be easier to place on the hand or remove from the hand of the wearer. The open wrist design provides ease of slipping a hand into or out of glove 300 . The ease of placement and removal of the glove from the hand of the wearer may provide for a longer lasting glove. [0044] Moreover, the open wrist portion 1305 may allow for better support and provide the wearer with a greater ability to adjust tightness of the glove as the wings may provide for greater variability of support. Furthermore, the open wrist portion 1305 may allow for greater air circulation throughout the glove 300 providing greater comfort for wearer and reduction of possible mildew formation in glove 300 . [0045] The present invention is disclosed above and in the accompanying drawings with reference to a variety of embodiments. The purpose served by the disclosure, however, is to provide an example of the various features and concepts related to the invention, not to limit the scope of the invention. One skilled in the relevant art will recognize that numerous variations and modifications may be made to the embodiments described above without departing from the scope of the present invention, as defined by the appended claims.
The invention relates to an athletic glove for supporting a hand of a wearer. The soccer glove improves performance through the use a three dimensional finger cap which forms at least a portion of at least one digit of the wearer's hand. The athletic glove also comprises an open wrist feature which allows for a greater degree of support, adjustability, comfort, and ease of access and removal
Briefly describe the main idea outlined in the provided context.
[ "[0001] This application is a continuation application of prior U.S. patent application Ser.", "No. 11/194,112, filed Jul. 29, 2005 the contents of which is incorporated herein by reference in its entirety.", "FIELD OF THE INVENTION [0002] The invention relates to a supportive glove for receiving the hand of a wearer for use in athletics.", "More particularly, the invention relates to a soccer goalkeeper's glove.", "BACKGROUND [0003] The gloves used by soccer goalkeepers, otherwise known as goalies, typically include a dorsal element and a palmar element, both being fashioned from latex foam, and an element for securing the glove to the goalkeeper's wrist.", "Although goalkeeper gloves are similar in these respects, there are various modes of goalkeeper glove design that vary with respect to durability, flexibility, and seam placement, thereby affecting the fit and feel of the glove along with the goalkeeper's ability to control the soccer ball.", "[0004] Goalkeeper glove characteristics are affected by the pattern from which the dorsal and palmar elements are cut and the securing mechanism used to attach the glove to the goalkeeper's wrist.", "Unlike traditional gloves fashioned from leather, cloth, or a knitted yarn, latex foam is the material of choice among goalkeeper glove designers because of its flexible and protective qualities.", "The use of latex foam, although having desirable characteristics, affects glove design by necessitating a dorsal and palmar element with multiple seams that may interfere with ball control or reduce durability.", "[0005] As noted, the pattern from which the dorsal and palmar elements are cut affects glove characteristics.", "The majority of goalkeeper gloves employ a variety of patterns for the dorsal and palmar elements including: the traditional cut, the gunn cut/rolled finger cut, the rifle cut pattern, or a negative/reuse stitch pattern [0006] In a traditional cut glove 10 , shown in FIGS. 1-2 , a dorsal element 11 and a palmar element 12 are each fashioned from a single section of latex foam material, with only palmar element 12 having an attached thumb region.", "Supplemental elements (not shown), formed from a flexible material, connect dorsal and palmar elements 11 and 12 in the second through fifth digit regions, thereby creating an interior space for each digit.", "In addition, the union of dorsal and palmar elements 11 and 12 with the supplemental elements creates a dorsal seam 13 and a palmar seam 14 on the periphery of dorsal and palmar elements 11 and 12 , respectively.", "The dorsal thumb region includes a separate, flexible supplemental element 15 sewn to the edge of the thumb area of palmar element 12 and to dorsal element 11 .", "This combination of elements gives traditional cut glove 10 a relatively flat, paddle-like configuration and palmar seam 14 limits the goalkeeper's control of the ball and reduces glove durability.", "[0007] A gunn cut glove 20 , shown in FIGS. 3-5 , includes a dorsal element 21 and a palmar element 22 that are each fashioned from a single section of latex foam material including regions for the first, second, and fifth digits and dorsal element 21 including regions for the second through fifth digits.", "The second and fifth digit regions of palmar element 22 have a greater width than corresponding regions of dorsal element 21 .", "To form the glove regions for the second and fifth digits, the wider palmar regions are flexed to meet the edges of the second and fifth digit regions of dorsal element 21 and then sewn, the flexed material defining a recess for the goalkeeper's digits.", "The dorsal thumb region is formed from a separate, flexible supplemental element 24 sewn to the edge of the thumb region of palmar element 22 and to dorsal element 21 .", "[0008] Unlike traditional cut glove 10 , gunn cut glove 20 contains only one seam 25 joining dorsal and palmar elements 21 and 22 in the digit regions due to the lack of supplemental elements.", "The flexing of the second and fifth digit regions of palmar element 22 and the resulting smooth palmar surface embodies the primary advantage of the gunn cut pattern over the traditional cut pattern.", "The digit regions of gunn cut glove 20 are rounded and lack seams on the palmar surface that may interfere with ball control.", "However, the gunn cut glove is more complex and costly to manufacture.", "Moreover, seam 26 at the base of the third and fourth digits may be uncomfortable and lack durability.", "[0009] In a rifle cut glove 30 , shown in FIGS. 6-8 , a dorsal element 31 and a palmar element 32 are each formed from a single section of foam material, with palmar element 32 , shown separately in FIG. 8 , including only the first, second, fourth, and fifth digit regions and dorsal element 31 including the second through fifth digit regions.", "The second digit region of palmar element 32 has a greater width than the corresponding region of dorsal element 31 .", "A single, separate section 33 of latex foam material, also shown in FIG. 8 , forms the third digit region of palmar element 31 and is sewn to palmar element 31 at the base of the third digit region.", "Supplemental elements (not shown), formed from a flexible material, connect edges of the dorsal and palmar elements in the third, fourth, and fifth digit regions, thereby creating an interior space for each digit.", "The union of dorsal and palmar elements 31 and 32 with the supplemental elements creates seams 34 and 35 on the periphery of the dorsal and palmar elements, respectively.", "To form the glove regions for the second digit, the wider palmar region is flexed to meet the edges of the second digit region of dorsal element 31 and then sewn, the flexed material thereby defining a recess for the goalkeeper's second digit.", "The dorsal thumb region includes a separate, flexible supplemental element 36 sewn to the edge of the thumb region of palmar element 32 and to dorsal element 31 .", "[0010] The primary advantage of rifle cut glove 30 lies in the rounded palmar surface of the second digit.", "Like gunn cut glove 20 , rifle cut glove 30 is more complex and costly to manufacture than traditional cut glove 10 .", "In addition, seam 37 at the base of the third digit may cause discomfort and represent an area of low durability.", "[0011] The traditional cut, gunn cut, and the rifle cut pattern goalkeeper gloves have similar wrist securing apparatus which includes a wrist element 50 ( FIGS. 1-7 ) comprising a circumferential band of elastic material.", "The goalkeeper inserts his/her hand into the circumferential band of material to secure the glove.", "The circumferential band is sewn to the palmer and dorsal portions of the glove.", "A strap 52 is attached to wrist element 50 to surround and releasably attach a substantial portion of the circumference of wrist element 50 .", "However, use of wrist element 50 provides a hindrance to securing the goalkeeper's hand quickly.", "In addition, the wrist element 50 provides a goalkeeper with adequate flexibility in wrist area of the glove.", "[0012] Therefore, there is a need in the art for a goalkeeper's glove that overcomes the disadvantages of the prior art gloves and provides a goalkeeper with a glove that gives a greater degree of flexibility and fit, is easy to put on, and exhibits superior ball control characteristics.", "SUMMARY OF THE INVENTION [0013] The invention relates to an athletic glove for supporting and receiving a hand of a wearer.", "The glove includes a palmar element and a dorsal element.", "The palmar element is formed of a first shock-absorbing material and is located to substantially cover a palmar metacarpal area of the wearer's hand and a palmar side of a first digit, a second digit, a third digit, a fourth digit, and a fifth digit of the wearer's hand.", "The palmar element also has at least one additional section that wraps around a medial or a lateral side of at least one of the second through fifth digits to cover at least a portion of a dorsal side of the digit wrapped by the at least one additional section.", "The dorsal element is located opposite the palmar element and substantially covers a dorsal metacarpal area of the wearer's hand and at least a portion of the dorsal side of the second digit, the third digit, the fourth digit, and the fifth digit that are not covered by the at least one additional section of the palmar element.", "[0014] The athletic glove further includes at least one three dimensional finger cap which forms at least a portion of at least one digit of the wearer's hand.", "The athletic glove also comprises an open wrist feature which allows for a greater degree of adjustability or fit.", "Furthermore, the open wrist feature allows for better support and the ability to adjust tightness of the glove.", "The palmar element of the glove includes two wing portions that attach to a stretchable material to secure the glove to the wrist of the wearer.", "[0015] The advantages and features of novelty characterizing the invention are pointed out with particularity in the appended claims.", "To gain an improved understanding of the advantages and features of novelty, however, reference may be made to the following descriptive matter and accompanying drawings that describe and illustrate various embodiments and concepts related to the invention.", "DESCRIPTION OF THE DRAWINGS [0016] FIG. 1 is a plan view of the dorsal side of a traditional cut glove.", "[0017] FIG. 2 is a plan view of the palmar side of the traditional cut glove.", "[0018] FIG. 3 is a plan view of the dorsal side of a gunn cut glove.", "[0019] FIG. 4 is a plan view of the palmar side of the gunn cut glove.", "[0020] FIG. 5 is an illustration of a first portion of the pattern from which the palmar element of the gunn cut glove is formed.", "[0021] FIG. 6 is a plan view of the dorsal side of the rifle cut glove.", "[0022] FIG. 7 is a plan view of the palmar side of the rifle cut glove.", "[0023] FIG. 8 is an illustration of the patterns from which the palmar element of the rifle cut glove is formed.", "[0024] FIG. 9 is a plan view of the palmar side of the soccer glove in accordance with an aspect of the invention.", "[0025] FIG. 10 is an additional plan view of the palmar side of the soccer glove in accordance with an aspect of the invention.", "[0026] FIG. 11 is a plan view of the dorsal side of the soccer glove in accordance with an aspect of the invention.", "[0027] FIG. 12 is a plan view of the use of multiple finger caps in accordance with an aspect of the invention.", "[0028] FIG. 13 illustrates an open wrist portion in accordance with an aspect of the invention.", "DETAILED DESCRIPTION OF THE INVENTION [0029] Referring to the accompanying figures, a goalkeeper's glove in accordance with various aspects of the invention is disclosed.", "The figures illustrate only the glove intended for use on the right hand of a wearer.", "It should be understood by those skilled in the art that a left glove, such glove being a mirror image of the right glove, is included within the scope of the invention.", "In distinguishing portions of the glove or the hand received by the glove, reference will be made to areas of the hand, including a dorsal, palmar, lateral, and medial side;", "the five digits;", "and an area corresponding to the metacarpal bones.", "Such references are not intended to demarcate precise areas.", "Rather, they are intended to delineate general areas to aid in discussion.", "[0030] With reference to FIGS. 9-13 , a goalkeeper's glove according to the present invention is illustrated, wherein the primary elements of a glove 300 include a dorsal element 202 ( FIG. 11 ) and a palmar element 302 ( FIG. 9 ).", "Dorsal element 202 and palmar element 302 may be formed of any suitable material or combination of suitable materials, including a shock-absorbing, lightweight, foamed, natural latex rubber, ranging in thickness from two to five millimeters, bonded to a lightweight scrim of poly-based cells of approximately two to three millimeters.", "In addition, a textile layer may be bonded to the interior surface of palmar element 302 to provide enhanced comfort.", "[0031] FIGS. 9-10 illustrate palmar element 302 in an aspect of the invention.", "Palmar element 302 may be designed to cover a substantial portion of the palmar area of the wearer's hand.", "In addition, palmar element 302 may form a continuous section of material.", "[0032] Palmar element 302 may include a palmar metacarpal area 303 for covering the palmar metacarpal bones and the joints between the metacarpals and phalanges of the second through fifth digits and palmar digit areas 304 a - 304 e for covering the palmar areas of the first through fifth digits, respectively.", "One skilled in the art will realize that the term first digit conventionally refers to the thumb, the term second digit conventionally refers to the index finger, the term third digit conventionally refers to the middle finger, the term fourth digit refers to the ring finger, and the fifth digit refers to the pinky finger.", "[0033] Extending from palmar digital areas 304 a , 304 b , and 304 e are additional sections 306 a , 306 b , and 306 e , respectively which are part of the material comprising palmar element 302 .", "The purpose of additional sections 306 are to wrap around digits, thereby creating a seamless surface that extends from the palmar area, around the sides of the digits, and to the dorsal area.", "A seamless surface on the medial side of the fifth digit and on lateral sides of the first and second digit create a configuration wherein the digital regions of the glove do not have seams that may interfere with ball control while catching, handling, and throwing.", "[0034] With respect to the first digit, additional section 306 a may wrap over line 310 a so as to cover the lateral side of the first digit and at least a portion of the dorsal portions of the first digit.", "Additional section 306 a may be sewn to palmar digital area 304 a and first supplemental element 402 to create a cavity for the first digit.", "A V-shaped cut 308 a in palmar element 300 may form a flex notch 321 a ( FIG. 10 ) generally at the junction of palmar metacarpal area 302 and first palmar digital area 304 a. [0035] In forming a cavity for receiving the second digit, additional section 306 b may wrap over line 310 b so as to cover the lateral side of the second digit and dorsal portions of the second digit.", "Additional section 306 b may be sewn to palmar digital area 304 b along the medial side and tip area, and abuts dorsal digital area 204 b ( FIG. 11 ) across the dorsal surface of the second digit.", "A straight cut 308 b in palmar element 300 may form a flex notch 321 b ( FIG. 10 ) generally at the junction of palmar metacarpal area 302 and palmar digital area 304 b. [0036] Similarly, additional section 306 e may wrap over line 310 e so as to cover the medial side of the fifth digit and dorsal portions of the fifth digit.", "Additional section 306 e may be sewn to palmar digital area 304 e along the lateral side and tip area and abuts dorsal digital area 204 e ( FIG. 11 ) across the dorsal surface of the fifth digit.", "A straight cut 308 e in palmar element 300 may form a flex notch 321 e ( FIG. 10 ) generally at the junction of palmar metacarpal area 302 and palmar digital area 304 e. [0037] FIG. 11 illustrates the dorsal side of glove 300 .", "Dorsal element 202 may include a dorsal metacarpal area 203 for covering the dorsal metacarpal bones and the joints between the metacarpals and phalanges of the first through fifth digits and dorsal digit areas 204 a - 204 e for covering the dorsal areas of the first through fifth digits, respectively.", "Dorsal element 202 may also comprise a first finger cap 1101 , a second finger cap 1105 , a stretchable material 1110 , and an intermediate material 1115 .", "In an alternative embodiment, the first digit may include a secondary stretchable material (not shown) that may be used to cover the dorsal area of the first digit.", "The secondary stretchable material may be sewn to the stretchable material 1110 .", "[0038] In an aspect of the invention, the union of additional section 306 b with dorsal digital area 204 b is accomplished by sewing additional section 306 b and dorsal digital area 204 b such that the edge of additional section 306 b abuts dorsal digital area 204 b .", "This configuration forms a flexible joint in the dorsal surface.", "The union of additional section 306 e with dorsal digital area 204 e is accomplished in a similar manner and creates a second flexible joint.", "As noted, the seamless surface created by the wrapping of additional sections 306 around digits enhances ball control.", "The joints in the dorsal surface of the second and fifth digits promote this goal through increased flexibility in these digits.", "In other aspects of the invention, the possibility of using one or more additional sections to wrap an individual digit are not limited by the particular digit.", "[0039] Finger cap 1101 and 1105 may be molded from a polymer such as polyethylene, polyurethane, polyamide, polyester, polyolefin, or vinyl.", "The molding process may produce a three dimensional representation of any of the first through fifth digits or portions thereof.", "For example, finger cap 1101 along with stretchable material 1110 and intermediate material 1115 may form the dorsal portion of a third digit such as digit area 204 c .", "Portions of finger cap 1101 may be sewn to stretchable material 1110 and intermediate material 1115 .", "Finger cap 1101 and intermediate material 1115 may be sewn to palmar digit area 304 c to create a cavity for the third digit.", "Similarly, finger cap 1105 along with stretchable material 1110 and intermediate material 1115 may be sewn together to form the dorsal portion of a fourth digit.", "Finger cap 1105 and intermediate material 110 may be sewn to palmar digit area 304 d to create a cavity for the fourth digit.", "[0040] Those skilled in the art will realize that finger caps may be molded for use on any of the first through fifth digits.", "For example, FIG. 12 illustrates the use of finger caps 1205 - 1225 on each of the digits of the wearer.", "Finger caps may provide a goalie's fingers a greater degree of performance and support due to the use of a molded shock-absorbent material.", "The finger caps may mimic the natural anatomy of a wear's digits due to the molded three dimensional shapes of the finger caps.", "The molded three dimensional shapes may provide a greater degree of performance.", "In addition, the use of the finger caps provides the goalie with a greater degree of ball control due to additional finger flexibility given to the various fingers inserted in the finger caps and the reduction of seams on the palmar portion of the glove.", "In an aspect of the invention, the molded three dimensional finger caps may also include some surface indentations or different size panels representing various areas of a wearer's digits.", "[0041] Both the stretchable material 1110 and the intermediate material 1115 may comprise an elastic material.", "The stretchable material 1110 and the intermediate material 1115 may deform in the presence of a tensile force, thereby stretching to accommodate wearers with various finger dimensions.", "The stretchable material 1110 and the intermediate material 1115 may be any material with the ability to substantially return to an original size and shape following deformation.", "In addition, the stretchable material 1110 and the intermediate material 1115 may be made from various lightweight, breathable materials.", "[0042] FIG. 13 illustrates an open wrist portion 1305 in accordance with an aspect of the invention.", "Referring to FIG. 13 , palmar element 302 includes a first wing portion 1310 and a second wing portion 1315 .", "The first wing portion 1310 attaches to stretchable material 1110 through the use of a hook and loop fastener system.", "The second wing portion 1315 overlaps the first wing portion 1110 to form a cylinder that encircles a wrist of the hand of the wearer.", "The second wing portion 1315 may be connected to the first wing portion 1310 using a hook and loop fastener system.", "Those skilled in the art will realize that other fastener systems may be utilized to connect the wing portions and the stretchable material 1110 to provide a releasable fastener system.", "[0043] The open wrist portion 1305 may provide a goalkeeper with adequate flexibility in the wrist area of the glove.", "In addition, the glove 300 may be easier to place on the hand or remove from the hand of the wearer.", "The open wrist design provides ease of slipping a hand into or out of glove 300 .", "The ease of placement and removal of the glove from the hand of the wearer may provide for a longer lasting glove.", "[0044] Moreover, the open wrist portion 1305 may allow for better support and provide the wearer with a greater ability to adjust tightness of the glove as the wings may provide for greater variability of support.", "Furthermore, the open wrist portion 1305 may allow for greater air circulation throughout the glove 300 providing greater comfort for wearer and reduction of possible mildew formation in glove 300 .", "[0045] The present invention is disclosed above and in the accompanying drawings with reference to a variety of embodiments.", "The purpose served by the disclosure, however, is to provide an example of the various features and concepts related to the invention, not to limit the scope of the invention.", "One skilled in the relevant art will recognize that numerous variations and modifications may be made to the embodiments described above without departing from the scope of the present invention, as defined by the appended claims." ]
[0001] This application claims Paris Convention priority of EP 06 022 373.2 filed Oct. 26, 2006 the complete disclosure of which is hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] The invention concerns a flow-through microfluidic nuclear magnetic resonance (=NMR)-chip comprising a substrate which is planar in an yz-plane with a sample chamber within the substrate, the sample chamber being elongated and having walls which run parallel to the z-direction the substrate having a thickness in x-direction of a Cartesian xyz-coordinate system between 50 μm and 2 mm, and at least one planar receiving and/or transmission coil with conductor sections the coil being arranged at least on one planar surface of the substrate, wherein the extension of the sample chamber along the z-direction exceeds the extension of the coil along the z-direction. [0003] Such a flow-through microfluidic NMR-chip is known from [6]. [0004] Small-volume samples for nuclear magnetic resonance (NMR) spectroscopy consist for example of less than a few microliters of an analyte in solution. Such small samples are conveniently handled using microfluidic channels fabricated in different types of substrates, together with valves, pumps, and other miniaturized sample preparation and transportation means. NMR analysis in so-called lab-on-a-chip or micro total analysis systems (microTAS) is of great interest. However, because NMR has inherently a low sensitivity and since the NMR signal is proportional to the sample volume, signal-to-noise ratio becomes very weak for such small samples. One of the means to increase the sensitivity of the NMR experiment for small-volume sample is the use of miniaturized radio frequency (=RF) coils for signal detection. Coils which show dimensions of a few millimeters down to tens of micrometers can be fabricated by photolithography directly on the microfluidic substrate. Nevertheless, the quality of NMR spectra obtained so far from samples contained in microfluidic NMR-chips has been rather poor and appropriate coil-sample configurations remain to be designed in order to improve the NMR detection performance. [0005] In [1] an NMR apparatus is disclosed wherein a planar, lithographic microcoil is fabricated onto a substrate onto which has been etched or grooved channels to serve as capillaries through which analytical compound flows. [2] describes an integrated miniaturized device for processing and NMR detection of liquid phase samples. Essential performance criteria of an NMR probe are its spectral resolution, sensitivity and homogeneity of the RF field of the microcoil (=B1 homogeneity). While the NMR detection performance is largely determined by the NMR coil—sample configuration, none of the above mentioned documents describes an arrangement yielding good NMR performance. In fact, the NMR performance of planar microcoils to date has been rather poor, in particular with respect to spectral resolution. [0006] In [3] a rectangular Helmholtz coil geometry with the aim of improving B1 homogeneity is proposed, as shown in FIG. 17 c . The coil 102 was combined with a rectangular closed cavity 202 of dimensions smaller than the dimensions of the coil 102 for sample containment. The authors acquired a proton spectrum of a vinyl plastisol material at 63.5 MHz, which resulted in a very broad spectrum. [0007] In [4] a flow-through microfluidic NMR-chip is disclosed with an enlarged sample chamber and a planar circular coil. A proton spectrum of sucrose obtained from that prior art microfluidic NMR-chip configuration is illustrated in FIG. 18 a . The spectrum was acquired at 300 MHz with a 1M sucrose sample concentration in D 2 O. The microcoil was a two-turn circular spiral with an inner diameter of 2 mm. The active sample volume was 470 nL. The measured linewidth was 20 Hz and splitting of the anomeric proton peak could not be observed. B1 homogeneity performance of the same prior art microfluidic NMR-chip configuration is illustrated in FIG. 18 b . The signal amplitudes measured for a 270° was 54% of that obtained for a 90° pulse. Typical specifications for a conventional NMR probe require at least 50% signal amplitude for an 810° pulse. This prior art configuration was far from meeting these specifications. [0008] Walton et al. [5] used a circular coil geometry 100 in combination with a spherical sample chamber 200 ( FIG. 17 a ). The authors did not acquire 1 H spectra, but derived qualitative proton line widths on the order of 20 Hz (at 300 MHz) from 31 P measurements. It is pointed out that standard shim coils were ineffective in further improving the resolution. With a linewidth of 20 Hz, fine features of proton spectra (such as J-coupling) cannot be resolved. An additional drawback of their design is a low sensitivity due to a small filling-factor. [0009] In order to improve spectral resolution, the configuration illustrated in FIG. 17 b was proposed by Wensink et al. [6]. It consists of a straight channel 201 in line with the static magnetic field combined with a circular microcoil 101 placed in the central region of the channel. With this configuration, the authors measured a linewidth of 1.3 Hz at 60 MHz. This value would correspond to a proton linewidth of 6.5 Hz at 300 MHz. This is still not adequate to perform high-resolution NMR spectroscopy. It can be shown that such a configuration would yield poor B1 homogeneity performance. [0010] In summary, none of the prior art configurations simultaneously yielded a good spectral resolution, high sensitivity and large B1 homogeneity. [0011] It is therefore an object of the invention to suggest a flow-through microfluidic NMR-chip with improved resolution, sensitivity as well as B1 homogeneity in order to achieve good NMR performance within microfluidic NMR-chips. SUMMARY OF THE INVENTION [0012] This object is achieved by the extension of the coil along the z-direction being larger than its extension along the y-direction. The coil comprises coil conductor sections which run mainly in the z-direction. The thickness of the substrate in x-direction is preferably between 100 μm and 2 mm, in particular between 200 μm and 2 mm, most preferably between 200 μm and 1 mm. [0013] The basic idea of the invention is to adjust the geometry of the coil and the geometry of the sample chamber in order to avoid B0 field distortions on the one hand and to improve B1 homogeneity on the other hand. [0014] Spectral resolution is a direct consequence of distortions of the static magnetic field B 0 introduced by the NMR probe within the sample. In the case of a microfluidic NMR-chip, B0 distortion is mainly determined by the sample chamber shape as well as coil geometry and positioning of the wires with respect to the sample chamber. Sensitivity and B1 homogeneity are mainly determined by the characteristics of the B1 magnetic field produced by the NMR coil within the sample volume. The spatial dependence of the B1 field depends on the coil geometry and arrangement with the sample chamber. [0015] Due to the elongated sample chamber distortions of the homogeneity of the static magnetic field in the central region of the sample chamber can be avoided or at least minimized. The inventive NMR-chip comprises a coil which is also elongated in z-direction. The center of the sample chamber and the center of the coil are preferably located at the same z-value. It is advantageous that the extension of the sample chamber in z-direction exceeds the extension of the coil in z-direction, in order to avoid negative effects at the edges of the sample chamber. Provided that the z-axis is aligned with the static magnetic field B 0 this configuration, in which the sample chamber as well as a substantial portion of the coil are orientated in the z-direction, results in an improved B0 homogeneity, since the elongated sample chamber minimizes B0 distortion within the central part of the sample. The orientation of a substantial portion of the conducting wires along z-direction effects that no significant distortion of the B0 field within the sample volume takes place and therewith an improved spectral resolution can be achieved. Because of the orientation of the conducting wires along z-direction a homogeneous B1-field along the z-axis is produced. The inventive sample-coil arrangement improves the Signal to Noise ratio thus increasing sensitivity of the NMR-chip. [0016] Compared to prior art, the inventive coil-sample configuration allows one to simultaneously improve spectral resolution while achieving high sensitivity and B1 homogeneity. The new configuration makes it possible to shim the sample using conventional shim systems since small scale distortions through the coil and chip are neglectable with this invention and only large scale distortions of the probe remain. [0017] In a preferred embodiment the coil has a rectangular shape. In this case a maximum quantity of the conductor sections is oriented in z-direction therewith not disturbing the magnetic field B 0 within the sample chamber. Note that this argument scales and thus is true for all sizes of coil ranging from 50 μm to several millimeter. However a convential shim system is fixed and does not scale with the coil. While there is not much influence on a small coil (e.g. 50 μm) it may have some influence for larger coils (e.g. some millimeters). Because of this, it should be noted that other coil geometries which show an elongated shape can also be suitable for lager coils, e.g. an elliptic shaped coil. In this case most of the conductor sections do not run parallel to the z-direction. Yet each conductor section can theoretically be split in a parallel part (projection on the z-direction) and a perpendicular part (projection perpendicular to z-direction). The object of the invention is achieved if the parallel parts of most of the conductor sections exceed the perpendicular part. [0018] The ratio of the extension of the coil along the z-direction and the extension of the coil along the y-direction is preferably between 1.1 and 5. [0019] It is advantageous if one coil is arranged on both outer surfaces of the substrate, which are connected to form a Helmholtz arrangement. With this configuration the B1 homogeneity can be further improved. The Helmholtz arrangement consists preferably of two mirror symmetric planar coils. [0020] A preferred embodiment of the inventive NMR-chip provides a plurality of coils, in particular two coils, wherein each coil is tuned to a plurality of different frequencies. Therewith signals from different nuclei can be received. [0021] In an advantageous development of this embodiment the coils are inductively decoupled. This leads to improved performance of multinuclear NMR experiments. It should be noted that any reduction of the difference in susceptibility is of advantage, it need not being “perfectly” matched. [0022] Further preferred is an embodiment in which the conductor sections of the coils are arranged multilayered. Also microcoil cross-wires are preferably arranged multilayered. As a result, inductively decoupled coils can be fabricated onto one surface of the substrate in the same production process. [0023] In a particularly preferred embodiment one of the coils is rectangular and the other coil forms a butterfly arrangement. The odd-symmetry of the x-component of the rf field produced by the butterfly coil in the xy plane allows one to efficiently decouple both coils. [0024] In order to minimize distortion of the static magnetic field it is preferred that the magnetic susceptibilities of the coil conductor sections are matched to the susceptibilities of their respective environment, for example to nitrogen gas surrounding the coil wires. Microcoil cross-wires are then also matched to the susceptibilities of their respective environment. [0025] It is advantageous when the coil is equipped with integrated shielding plates. The shielding plates prevent the RF field B 1 to penetrate the sample in regions external from the coil thereby improving the field distribution. The shielding plates may comprise a copper layer acting as eddy current shielding. [0026] The material of the coil comprises preferably copper, gold and/or silver. [0027] It is advantageous if the ratio of the extension of the sample chamber along the z-direction and the extension of the coil along the z-direction is greater than 1.5. The sample chamber exceeds the extension of the coil in z-direction thereby reducing B0-distortion, which reduces with increasing length (extension in z-direction) of the sample chamber. [0028] In a preferred embodiment of the inventive NMR-chip the substrate comprises two parts, which are bonded together. In at least one of the substrate parts an elongated channel is etched which form the sample chamber when the substrate parts are bonded together. [0029] The substrate is preferably dielectric and electrical insulating, in particular made of glass, quartz or silica. In particular borosilicate glass is suitable as substrate material. [0030] In a preferred embodiment the magnetic susceptibility of the substrate is matched to the susceptibility of a solvent, in particular to the susceptibility of water. Thus no susceptibility changes occur at the interface of the substrate and the solvent of the sample. Yet, this is only possible for one selected sample (preferable one which is investigated most often) or for an imaginary “averaged” sample, whose susceptibility is the average susceptibility of the most common samples. [0031] It is preferred that the centers of the sample chamber, of the coil and of the substrate coincide within the yz-plane. This minimizes B0 distortion and facilitates shimming. [0032] In a preferred embodiment the NMR-chip shows a length along the z-direction of less than 50 mm, in particular less than 25 mm, most preferably less than 20 mm, and a width along the y-direction of less than 30 mm, in particular less than 15 mm. [0033] In a special embodiment two or more sample inlets are provided upstream of the sample chamber. Different samples can be mixed directly within the inventive NMR-chip. [0034] The invention also concerns a NMR apparatus comprising a superconducting magnet, a NMR-spectrometer and a probe with a NMR-chip as described above, wherein the NMR-chip is aligned along a static magnetic field in z-direction, which is produced from the superconducting magnet in operation. [0035] Further advantages can be extracted from the description and the enclosed drawing. The features mentioned above and below can be used in accordance with the invention either individually or collectively in any combination. The embodiments mentioned are not to be understood as exhaustive enumeration but rather have exemplary character for the description of the invention. [0036] The invention is shown in the drawing. BRIEF DESCRIPTION OF THE DRAWING [0037] FIG. 1 shows optimal B0 and B1 field profiles (theoretical); [0038] FIG. 2 shows a cut-out of a schematic top view of an inventive flow-through microfluidic NMR-chip; [0039] FIG. 3 shows a schematic top view of an inventive flow-through microfluidic NMR-chip; [0040] FIG. 4 shows a schematic perspective view of an inventive flow-through microfluidic NMR-chip; [0041] FIG. 5 shows the B0 profile produced by an elongated sample chamber and a B1 profiles for a rectangular coil with and without shielding plates; [0042] FIG. 6 shows a schematic top view of an inventive flow-through microfluidic NMR-chip with integrated shielding plates; [0043] FIG. 7 shows a B0 distortion produced by a cross-wire section of a rectangular coil with and without magnetic susceptibility compensation; [0044] FIG. 8 shows the principle of susceptibility compensation using layered conductors; [0045] FIG. 9 shows a schematic perspective view an inventive flow-through microfluidic NMR-chip with an integrated Helmholtz microcoil arrangement; [0046] FIG. 10 shows a schematic top view of an inventive flow-through microfluidic NMR-chip comprising two inductively decoupled coils, one of them forming a butterfly coil geometry; [0047] FIG. 11 shows a schematic cross sectional view of the NMR-chip according to FIG. 10 ; [0048] FIG. 12 shows a schematic top view of an inventive flow-through microfluidic NMR-chip comprising two sample inlets upstream of the sample chamber; [0049] FIG. 13 shows a schematic a schematic top view of an inventive NMR-apparatus for spectrometer applications with an inventive NMR-chip; [0050] FIG. 14 shows a proton NMR spectrum of sucrose derived by a preferred embodiment of the inventive NMR-chip; [0051] FIG. 15 shows the nutation curve illustrating B1 homogeneity for the configuration used for obtaining the NMR-spectrum of FIG. 14 ; [0052] FIG. 16 shows a Heteronuclear Multiple Quantum Correlation (HMQC) spectrum measured with a NMR-chip shown in FIG. 10 and FIG. 11 . [0053] FIG. 17 a shows a circular coil geometry combined with a spherical sample chamber according to [5] (PRIOR ART); [0054] FIG. 17 b shows a straight channel in line with the static magnetic field combined with a multi-turn circular microcoil placed in the central region of the channel according to [6] (PRIOR ART); [0055] FIG. 17 c shows a rectangular coil geometry combined with a rectangular cavity of dimensions smaller than the coil according to [3] (PRIOR ART); [0056] FIG. 18 a shows the spectral resolution on a sucrose sample with a configuration according to [4] (PRIOR ART); and [0057] FIG. 18 b shows the nutation curve illustrating B1 homogeneity for a configuration according to [4] (PRIOR ART); DESCRIPTION OF THE PREFERRED EMBODIMENT [0058] FIG. 1 shows an ideal B0 static magnetic field profile 3 and B1 RF field profile 4 to be achieved within a sample to be examined. With the inventive NMR-chip these ideal profiles can be approximated and thus good performance with microfluidic NMR-chips can be achieved. [0059] A cut-out of the inventive NMR-chip is disclosed in FIG. 2 . A sample chamber 2 within a planar substrate 5 is elongated and has walls which run parallel to the z-direction. A rectangular planar coil 1 is provided having conductor sections 11 , which also run parallel to the z-direction, in the sense that projection of 11 on the z-axis is larger than the projection on the y-axis. The dashed lines show one of the possible deviations from the straight lines. For simplicity and without loss of generality we will only show the case of straight lines in the following figures. Closing sections of the coil 1 and of the sample chamber 2 are not represented in FIG. 2 on purpose for they will be discussed later. During use of the inventive NMR-chip within a NMR-spectrometer the static magnetic field B 0 is aligned in z-direction (see FIG. 3 ). Since the elongated sample chamber 2 is also aligned in z-direction B0 distortion are minimized within the central part of the sample chamber 2 . Conductor sections 11 do not produce significant distortion of the B0 field within the sample volume, and produce a homogeneous B1 field along the z-axis. [0060] FIG. 3 and FIG. 4 show a top view and a perspective view respectively of a preferred embodiment of the invention derived from the configuration shown in FIG. 2 . [0061] The substrate 5 has a length L 1 , a width W 1 , is preferable made from a glass material or quartz. It comprises two substrate parts 51 , 52 with thicknesses t 1 , t 2 which are bonded together. An elongated channel is etched on the lower surface of a first planar substrate part 51 and on the upper surface of the second substrate part 52 . The sample chamber 2 can also be formed by etching only one of the substrate parts 51 , 52 , as shown in FIG. 11 . The dimensions of the inventive NMR-chip are mainly defined by the dimensions of the substrate: Substrate surface (L 1 *W 1 )<15 cm 2 Substrate length 5 mm<L 1 <50 mm Substrate width 3 mm<W 1 <30 mm (W 1 <L 1 ) Substrate thickness 100 μm<(t 1 +t 2 )<2 mm, [0066] The NMR sample chamber 2 is formed by the cavities etched in the first 51 and second planar glass substrate part 52 , by assembling the substrate parts 51 , 52 onto each other. The sample chamber 2 has a finite length L 2 , a width W 2 , and a channel depth d 1 , preferable with the following dimensions: Sample chamber length 200 μm<L 2 <16 mm Sample chamber width 50 μm<W 2 <2 mm (8*W 2 <L 2 ) Channel depth 50 μm<(2*d 1 )<1 mm Sample chamber volume 4 nanoliter<V 2 <30 microliter [0071] The coil 1 has closing cross-wire sections 12 perpendicular to the z-axis. The length L 3 of the coil 1 is greater than its width W 3 , thereby causing an elongated shape of the coil 1 . Preferably coil 1 has a rectangular shape, but can also have another elongated shape, such as an ellipsoid. In case coil 1 is used as a proton coil (i.e. for exciting 1 H-nuclei) its wires are advantageously made of copper (Cu), silver (Ag) or gold (Au). For optional compensation of magnetic susceptibility other materials may be added. Both single and multiple turn coils are suitable for NMR-spectroscopy purposes. The preferred dimensions for a rectangular coil 1 are the following: Coil wire thickness 5 μm<h 1 <50 μm (h 1 >2*skin depth) Coil wire width 10 μm<h 2 <800 μm Coil surface (L 3 *W 3 )<40 mm2 Coil length 100 μm<L 3 <10 mm (1.5*L 3 <L 2 ) Coil width 100 μm<W 3 <5 mm (W 2 <W 3 <2*W 2 and W 3 <L 3 ). [0077] FIG. 5 shows a realistic B0 field profile 31 and a B1 field profile 41 corresponding to the embodiment disclosed in FIG. 3 . The finite length L 2 of the sample chamber 2 produces a B0 distortion 31 proportional to z 2 . However, for larger coil (in millimeter range) this z 2 distortion can be compensated using standard room-temperature shims of commercially available magnets. For small coils (100 μm, range) this distortion can not be shimmed and it is important that the sample chamber exceeds the length of the coil. The B1 field profile 41 produced by the coil 1 resembles the ideal rectangular field profile 4 , apart from negative field regions caused by the coil cross-wires 12 . [0078] An arrangement allowing one to eliminate those negative B1 field values produced by the coil cross-wires 12 is disclosed in FIG. 6 . The NMR-chip 5 comprises integrated shielding plates 6 , which are placed above and below the coil 1 in z-direction in order to cover those parts of the sample chamber 2 which are not covered by the coil 1 therewith preventing the RF field B 1 to penetrate the sample in regions external from the coil 1 . The coil 1 and the shielding plates 6 are preferably arranged within the same plane. The corresponding B1 field profile 42 is illustrated in FIG. 5 , and becomes very close to the ideal rectangular field profile 4 of FIG. 1 . The shielding plates may comprise copper layers which act as an eddy current shielding. Said copper shielding plates 6 may show a thickness of 10 μm (at least twice the skin depth at the working frequency and preferably equal to the coil thickness h 1 ) and a length L s of 3 mm (Ls>(L 2 −L 3 )/2). The width W s of the shielding plates 6 should be greater than the width W 2 of the sample chamber. [0079] In addition to B0 distortion 31 produced by the finite length L 2 of the sample chamber, a B0 distortion 32 produced by diamagnetic coil cross-wires 12 is illustrated in FIG. 7 . Such a B0 distortion 32 is difficult to shim and limits the overall spectral resolution at high static field B 0 . The distortion 32 of the static field B 0 can be further reduced by adding a compensating layer 122 between the substrate 5 and the coil conductor 121 of the coil cross wire 12 as shown in FIG. 8 . The susceptibility of the compensating layer 122 has to have the opposite sign as the susceptibility of the coil conductor 121 . The effect of such a compensating layer 122 on B0 distortion is illustrated in FIG. 7 (profile 33 ). One can see that the B0 distortion 32 produced by diamagnetic coil cross-wires 12 is distinctly reduced. [0080] An embodiment of the invention featuring two coils 1 , each on one external surfaces of the substrate 5 is disclosed in FIG. 9 . The coils 1 are connected to form a Helmholtz arrangement 7 . A high B1 homogeneity performance can be obtained when the coil widths W 3 are approximately equal to twice the substrate thickness (t 1 +t 2 ). [0081] FIG. 10 discloses an embodiment of a flow-through microfluidic NMR-chip 5 comprising two inductively decoupled coils 1 , 1 ′, one of them forming a butterfly coil geometry 1 ′. A cross-section view of this embodiment is illustrated in FIG. 11 . Coil 1 produces a RF field B 1 mainly along the x-axis within the sample chamber 2 and is preferably tuned to proton frequency. Coil 1 ′ produces an RF field B 2 mainly along the y-axis within the sample chamber 2 and is preferably tuned to lower frequency nuclei, for example carbon. The two coils 1 , 1 ′ can be produced by photolithography on the same surface of the substrate 5 and are separated by an electrically insulating layer 8 as shown in FIG. 11 . [0082] An embodiment of the present invention comprising two sample inlets 21 a , 21 b upstream of the sample chamber 2 is shown in FIG. 12 . Such a NMR-chip allows one to introduce two different fluid samples A, B, one through each sample inlet 21 a , 21 b , and to monitor interaction between sample A and sample B by NMR while flowing the samples through the NMR-chip to an outlet 22 . [0083] FIG. 13 shows inventive microfluidic NMR-chip arranged within a superconducting magnet arrangement for use with a NMR-spectrometer 13 . The NMR-chip is mounted on a probe 14 . The end portions of the sample chamber 2 are connected to an inlet capillary 9 and an outlet capillary 10 respectively. The probe 14 is placed within a super-conducting magnet 15 so that the elongated sample chamber 2 along z-axis is aligned with the static field B 0 of the superconducting magnet 15 . A sample can be introduced into the NMR-chip through a sample port 16 via the inlet capillary 9 and can be taken out of the sample chamber through an outlet port 17 via the outlet capillary 10 . [0084] Compared to prior art, the present invention improves NMR detection performance within microfluidic NMR-chips in many respects. These improvements are illustrated for two examples of possible embodiments. [0085] The first example deals with a flow-through microfluidic NMR-chip with an integrated Helmholtz microcoil as shown in FIG. 9 . The microfluidic NMR-chip was formed by bonding together two glass substrates 51 and 52 with thickness t 1 =t 2 =500 μm, each comprising an etched half-channel. The resulting substrate 5 thickness was 1 mm. The sample chamber depth d 1 was 300 μm, width W 2 was 1.2 mm and length L 2 was 11.2 mm. Rectangular coils were patterned by photolithography on both surfaces of the NMR-chip. The coil width W 3 was 2 mm and the length L 3 was 2.8 mm. The coil wire was made of copper with a width 80 μm and thickness h 1 =15 μm. The active volume was 1 μL while the total volume in the NMR-chip was 4.8 μL. The glass NMR-chip dimensions were 22 mm (L 1 )×10 mm (W 1 ). [0086] FIG. 14 illustrates a proton NMR spectrum of sucrose acquired at 300 MHz using this example embodiment. The sample was 50 mM of sucrose in D 2 O. The splitting measured on the anomeric proton was 20%. The Signal-to-Noise(=SNR) value measured on the anomeric proton was 90 after 480 scans (with 0.7 Hz line broadening), corresponding to an SNR of 4.1/scan. This spectrum should be compared to the prior art spectrum of FIG. 18 a . Note that although the magnetic susceptibility of the copper wires was not compensated in this example, the resulting spectral resolution was excellent as a result of the inventive configuration. [0087] This example embodiment also provided excellent B1 homogeneity performance as illustrated in FIG. 15 . The excitation power was 16 W and the pulse duration was increased by increments of 1 μs, with a starting value of 2 μs. The signal amplitudes measured for a 450° and 810° pulse were respectively 96% and 86% of that obtained for a 90° pulse. This constitutes a large improvement compared to prior art performance illustrated in FIG. 18 b. [0088] The second example deals with another embodiment of the present invention comprising two magnetically decoupled coils tuned to two different frequencies, as shown in FIG. 10 and FIG. 11 . A channel with a depth of 150 μm was etched on the bottom surface of a 500 μm thick glass substrate 51 . This first substrate was bonded with a second 500 μm thick substrate 52 to form a 1 mm thick microfluidic substrate 5 . The sample chamber depth d 1 was 150 μm, width W 2 was 1.2 mm and length L 2 was 11.2 mm. The total NMR-chip sample volume was 2.3 μL, including inlet and outlet channels. The glass NMR-chip dimensions were 22 mm (L 1 )×10 mm (W 1 ). A rectangular coil 1 and a butterfly coil 1 ′ were microfabricated on the top surface of the substrate 5 , as shown in FIG. 10 and FIG. 11 . The width W 3 of the rectangular coil 1 was W 3 =2 mm and the length L 3 was L 3 =2.8 mm. Thus, the active sample volume was 500 nL. The wire forming the coil 1 was copper with a width of 80 μm and thickness h 1 of 10 μm. The rectangular microcoil 1 was doubled tuned to proton at 500 MHz and deuterium at 76 MHz. The butterfly microcoil 1 ′ comprised 8 straight copper conductor sections producing an RF field B 2 parallel to the substrate surface within the sample chamber. The wire width for the butterfly coil 1 ′ was 40 μm with 30 μm spacing between turns and thickness was 15 μm. The wires of the butterfly coil 1 ′ were electrically insulated from the wires of the rectangular coil 1 using a patterned polymer layer 8 . The butterfly coil 1 ′ was tuned to 125 MHz for carbon observe or decoupling. The measured decoupling between 13C and 1H channels after building the tuning and matching circuit was −26.5 dB at 500 MHz. This decoupling value was appropriate to perform multinuclei NMR experiments. FIG. 16 illustrates an HMQC spectrum acquired at 500 MHz using this example embodiment. The sample was 1M 13CH3OH+10% H 2 O+0.2 mg GdGl3/mL in D 2 O. LIST OF REFERENCE SIGNS [0000] A Sample B Sample B 0 Static magnetic field B 1 RF field d 1 Channel depth of the sample chamber h 1 Wire thickness of microcoil h 2 Wire width of microcoil L 1 Length of substrate (extension in z-direction) L 2 Length of sample chamber (extension in z-direction) L 3 Length of microcoil (extension in z-direction) L s Length of shielding plates (extension in z-direction) t 1 Thickness of first substrate part (extension in x-direction) t 2 Thickness of second substrate part (extension in x-direction) W 1 Width of substrate (extension in y-direction) W 2 Width of sample chamber (extension in y-direction) W 3 Width of microcoil (extension in y-direction)y W s Width of shielding plates (extension in y-direction) 1 ′ Butterfly microcoil 1 Rectangular planar microcoil 2 Sample chamber 3 Ideal profile of the static magnetic field B 0 4 Ideal profile of the RF magnetic field B 1 5 Microfluidic substrate 6 RF shielding plate 7 Helmholtz microcoil 8 Electrically insulating layer 9 Inlet capillary 10 Outlet capillary 11 Straight conductor sections 12 Microcoil cross-wire 13 NMR-spectrometer 14 Probe head 15 Superconducting magnet 16 Inlet port 17 Outlet port 31 Profile of the static magnetic field B 0 with z 2 distortion 32 Profile of the static magnetic field B 0 distortion introduced by diamagnetic cross-wires 33 Profile of the static magnetic field B 0 distortion introduced by cross-wires with susceptibility compensation 41 Profile of the RF magnetic field produced by a rectangular coil 42 Profile of the RF magnetic field produced by a rectangular coil with shielding plates 51 First planar substrate part 52 Second planar substrate part 100 Planar NMR microcoil (circular geometry) 101 Planar NMR microcoil (circular geometry) 102 Planar NMR microcoil (rectangular geometry) 121 Diamagnetic conductor layer 121 Paramagnetic layer 21 a Sample inlet 21 b Sample inlet 22 Sample outlet 200 Sample chamber (spherical geometry) 201 Channel 202 Closed cavity [1] U.S. Pat. No. 5,654,636 [2] U.S. Pat. No. 6,194,900 [3] Syms et al., J. Micromech. Microeng. 15 (2005), S1-S9 [4] Massin et al., J Mag Res, 164, (2003), 242-255 [5] Walton et al., Anal. Chem., 75 (2003), 5030-5036 [6] Wensink et al., Lab Chip, 5, (2005), 280-284
A flow-through microfluidic NMR-chip comprising a substrate ( 5 ) which is planar in an yz-plane with a sample chamber ( 2 ) within the substrate ( 5 ), the sample chamber ( 2 ) being elongated and having walls which run parallel to the z-direction, the substrate ( 5 ) having a thickness in x-direction of a Cartesian xyz-coordinate system between 100 μm and 2 mm, and at least one planar receiving and/or transmission coil ( 1, 1 ′) with conductor sections ( 11 ) the coil ( 1, 1 ′) being arranged at least on one planar surface of the substrate ( 5 ), wherein the extension of the sample chamber ( 2 ) along the z-direction exceeds the extension of the coil ( 1 ) along the z-direction is characterized in that the extension of the coil ( 1, 1 ′) along the z-direction is larger than its extension along the y-direction. The inventive NMR-chip facilitated NMR-spectroscopic measurements with improved resolution, sensitivity as well as B1 homogeneity.
Summarize the key points of the given patent document.
[ "[0001] This application claims Paris Convention priority of EP 06 022 373.2 filed Oct. 26, 2006 the complete disclosure of which is hereby incorporated by reference.", "BACKGROUND OF THE INVENTION [0002] The invention concerns a flow-through microfluidic nuclear magnetic resonance (=NMR)-chip comprising a substrate which is planar in an yz-plane with a sample chamber within the substrate, the sample chamber being elongated and having walls which run parallel to the z-direction the substrate having a thickness in x-direction of a Cartesian xyz-coordinate system between 50 μm and 2 mm, and at least one planar receiving and/or transmission coil with conductor sections the coil being arranged at least on one planar surface of the substrate, wherein the extension of the sample chamber along the z-direction exceeds the extension of the coil along the z-direction.", "[0003] Such a flow-through microfluidic NMR-chip is known from [6].", "[0004] Small-volume samples for nuclear magnetic resonance (NMR) spectroscopy consist for example of less than a few microliters of an analyte in solution.", "Such small samples are conveniently handled using microfluidic channels fabricated in different types of substrates, together with valves, pumps, and other miniaturized sample preparation and transportation means.", "NMR analysis in so-called lab-on-a-chip or micro total analysis systems (microTAS) is of great interest.", "However, because NMR has inherently a low sensitivity and since the NMR signal is proportional to the sample volume, signal-to-noise ratio becomes very weak for such small samples.", "One of the means to increase the sensitivity of the NMR experiment for small-volume sample is the use of miniaturized radio frequency (=RF) coils for signal detection.", "Coils which show dimensions of a few millimeters down to tens of micrometers can be fabricated by photolithography directly on the microfluidic substrate.", "Nevertheless, the quality of NMR spectra obtained so far from samples contained in microfluidic NMR-chips has been rather poor and appropriate coil-sample configurations remain to be designed in order to improve the NMR detection performance.", "[0005] In [1] an NMR apparatus is disclosed wherein a planar, lithographic microcoil is fabricated onto a substrate onto which has been etched or grooved channels to serve as capillaries through which analytical compound flows.", "[2] describes an integrated miniaturized device for processing and NMR detection of liquid phase samples.", "Essential performance criteria of an NMR probe are its spectral resolution, sensitivity and homogeneity of the RF field of the microcoil (=B1 homogeneity).", "While the NMR detection performance is largely determined by the NMR coil—sample configuration, none of the above mentioned documents describes an arrangement yielding good NMR performance.", "In fact, the NMR performance of planar microcoils to date has been rather poor, in particular with respect to spectral resolution.", "[0006] In [3] a rectangular Helmholtz coil geometry with the aim of improving B1 homogeneity is proposed, as shown in FIG. 17 c .", "The coil 102 was combined with a rectangular closed cavity 202 of dimensions smaller than the dimensions of the coil 102 for sample containment.", "The authors acquired a proton spectrum of a vinyl plastisol material at 63.5 MHz, which resulted in a very broad spectrum.", "[0007] In [4] a flow-through microfluidic NMR-chip is disclosed with an enlarged sample chamber and a planar circular coil.", "A proton spectrum of sucrose obtained from that prior art microfluidic NMR-chip configuration is illustrated in FIG. 18 a .", "The spectrum was acquired at 300 MHz with a 1M sucrose sample concentration in D 2 O. The microcoil was a two-turn circular spiral with an inner diameter of 2 mm.", "The active sample volume was 470 nL.", "The measured linewidth was 20 Hz and splitting of the anomeric proton peak could not be observed.", "B1 homogeneity performance of the same prior art microfluidic NMR-chip configuration is illustrated in FIG. 18 b .", "The signal amplitudes measured for a 270° was 54% of that obtained for a 90° pulse.", "Typical specifications for a conventional NMR probe require at least 50% signal amplitude for an 810° pulse.", "This prior art configuration was far from meeting these specifications.", "[0008] Walton et al.", "[5] used a circular coil geometry 100 in combination with a spherical sample chamber 200 ( FIG. 17 a ).", "The authors did not acquire 1 H spectra, but derived qualitative proton line widths on the order of 20 Hz (at 300 MHz) from 31 P measurements.", "It is pointed out that standard shim coils were ineffective in further improving the resolution.", "With a linewidth of 20 Hz, fine features of proton spectra (such as J-coupling) cannot be resolved.", "An additional drawback of their design is a low sensitivity due to a small filling-factor.", "[0009] In order to improve spectral resolution, the configuration illustrated in FIG. 17 b was proposed by Wensink et al.", "[6].", "It consists of a straight channel 201 in line with the static magnetic field combined with a circular microcoil 101 placed in the central region of the channel.", "With this configuration, the authors measured a linewidth of 1.3 Hz at 60 MHz.", "This value would correspond to a proton linewidth of 6.5 Hz at 300 MHz.", "This is still not adequate to perform high-resolution NMR spectroscopy.", "It can be shown that such a configuration would yield poor B1 homogeneity performance.", "[0010] In summary, none of the prior art configurations simultaneously yielded a good spectral resolution, high sensitivity and large B1 homogeneity.", "[0011] It is therefore an object of the invention to suggest a flow-through microfluidic NMR-chip with improved resolution, sensitivity as well as B1 homogeneity in order to achieve good NMR performance within microfluidic NMR-chips.", "SUMMARY OF THE INVENTION [0012] This object is achieved by the extension of the coil along the z-direction being larger than its extension along the y-direction.", "The coil comprises coil conductor sections which run mainly in the z-direction.", "The thickness of the substrate in x-direction is preferably between 100 μm and 2 mm, in particular between 200 μm and 2 mm, most preferably between 200 μm and 1 mm.", "[0013] The basic idea of the invention is to adjust the geometry of the coil and the geometry of the sample chamber in order to avoid B0 field distortions on the one hand and to improve B1 homogeneity on the other hand.", "[0014] Spectral resolution is a direct consequence of distortions of the static magnetic field B 0 introduced by the NMR probe within the sample.", "In the case of a microfluidic NMR-chip, B0 distortion is mainly determined by the sample chamber shape as well as coil geometry and positioning of the wires with respect to the sample chamber.", "Sensitivity and B1 homogeneity are mainly determined by the characteristics of the B1 magnetic field produced by the NMR coil within the sample volume.", "The spatial dependence of the B1 field depends on the coil geometry and arrangement with the sample chamber.", "[0015] Due to the elongated sample chamber distortions of the homogeneity of the static magnetic field in the central region of the sample chamber can be avoided or at least minimized.", "The inventive NMR-chip comprises a coil which is also elongated in z-direction.", "The center of the sample chamber and the center of the coil are preferably located at the same z-value.", "It is advantageous that the extension of the sample chamber in z-direction exceeds the extension of the coil in z-direction, in order to avoid negative effects at the edges of the sample chamber.", "Provided that the z-axis is aligned with the static magnetic field B 0 this configuration, in which the sample chamber as well as a substantial portion of the coil are orientated in the z-direction, results in an improved B0 homogeneity, since the elongated sample chamber minimizes B0 distortion within the central part of the sample.", "The orientation of a substantial portion of the conducting wires along z-direction effects that no significant distortion of the B0 field within the sample volume takes place and therewith an improved spectral resolution can be achieved.", "Because of the orientation of the conducting wires along z-direction a homogeneous B1-field along the z-axis is produced.", "The inventive sample-coil arrangement improves the Signal to Noise ratio thus increasing sensitivity of the NMR-chip.", "[0016] Compared to prior art, the inventive coil-sample configuration allows one to simultaneously improve spectral resolution while achieving high sensitivity and B1 homogeneity.", "The new configuration makes it possible to shim the sample using conventional shim systems since small scale distortions through the coil and chip are neglectable with this invention and only large scale distortions of the probe remain.", "[0017] In a preferred embodiment the coil has a rectangular shape.", "In this case a maximum quantity of the conductor sections is oriented in z-direction therewith not disturbing the magnetic field B 0 within the sample chamber.", "Note that this argument scales and thus is true for all sizes of coil ranging from 50 μm to several millimeter.", "However a convential shim system is fixed and does not scale with the coil.", "While there is not much influence on a small coil (e.g. 50 μm) it may have some influence for larger coils (e.g. some millimeters).", "Because of this, it should be noted that other coil geometries which show an elongated shape can also be suitable for lager coils, e.g. an elliptic shaped coil.", "In this case most of the conductor sections do not run parallel to the z-direction.", "Yet each conductor section can theoretically be split in a parallel part (projection on the z-direction) and a perpendicular part (projection perpendicular to z-direction).", "The object of the invention is achieved if the parallel parts of most of the conductor sections exceed the perpendicular part.", "[0018] The ratio of the extension of the coil along the z-direction and the extension of the coil along the y-direction is preferably between 1.1 and 5.", "[0019] It is advantageous if one coil is arranged on both outer surfaces of the substrate, which are connected to form a Helmholtz arrangement.", "With this configuration the B1 homogeneity can be further improved.", "The Helmholtz arrangement consists preferably of two mirror symmetric planar coils.", "[0020] A preferred embodiment of the inventive NMR-chip provides a plurality of coils, in particular two coils, wherein each coil is tuned to a plurality of different frequencies.", "Therewith signals from different nuclei can be received.", "[0021] In an advantageous development of this embodiment the coils are inductively decoupled.", "This leads to improved performance of multinuclear NMR experiments.", "It should be noted that any reduction of the difference in susceptibility is of advantage, it need not being “perfectly”", "matched.", "[0022] Further preferred is an embodiment in which the conductor sections of the coils are arranged multilayered.", "Also microcoil cross-wires are preferably arranged multilayered.", "As a result, inductively decoupled coils can be fabricated onto one surface of the substrate in the same production process.", "[0023] In a particularly preferred embodiment one of the coils is rectangular and the other coil forms a butterfly arrangement.", "The odd-symmetry of the x-component of the rf field produced by the butterfly coil in the xy plane allows one to efficiently decouple both coils.", "[0024] In order to minimize distortion of the static magnetic field it is preferred that the magnetic susceptibilities of the coil conductor sections are matched to the susceptibilities of their respective environment, for example to nitrogen gas surrounding the coil wires.", "Microcoil cross-wires are then also matched to the susceptibilities of their respective environment.", "[0025] It is advantageous when the coil is equipped with integrated shielding plates.", "The shielding plates prevent the RF field B 1 to penetrate the sample in regions external from the coil thereby improving the field distribution.", "The shielding plates may comprise a copper layer acting as eddy current shielding.", "[0026] The material of the coil comprises preferably copper, gold and/or silver.", "[0027] It is advantageous if the ratio of the extension of the sample chamber along the z-direction and the extension of the coil along the z-direction is greater than 1.5.", "The sample chamber exceeds the extension of the coil in z-direction thereby reducing B0-distortion, which reduces with increasing length (extension in z-direction) of the sample chamber.", "[0028] In a preferred embodiment of the inventive NMR-chip the substrate comprises two parts, which are bonded together.", "In at least one of the substrate parts an elongated channel is etched which form the sample chamber when the substrate parts are bonded together.", "[0029] The substrate is preferably dielectric and electrical insulating, in particular made of glass, quartz or silica.", "In particular borosilicate glass is suitable as substrate material.", "[0030] In a preferred embodiment the magnetic susceptibility of the substrate is matched to the susceptibility of a solvent, in particular to the susceptibility of water.", "Thus no susceptibility changes occur at the interface of the substrate and the solvent of the sample.", "Yet, this is only possible for one selected sample (preferable one which is investigated most often) or for an imaginary “averaged”", "sample, whose susceptibility is the average susceptibility of the most common samples.", "[0031] It is preferred that the centers of the sample chamber, of the coil and of the substrate coincide within the yz-plane.", "This minimizes B0 distortion and facilitates shimming.", "[0032] In a preferred embodiment the NMR-chip shows a length along the z-direction of less than 50 mm, in particular less than 25 mm, most preferably less than 20 mm, and a width along the y-direction of less than 30 mm, in particular less than 15 mm.", "[0033] In a special embodiment two or more sample inlets are provided upstream of the sample chamber.", "Different samples can be mixed directly within the inventive NMR-chip.", "[0034] The invention also concerns a NMR apparatus comprising a superconducting magnet, a NMR-spectrometer and a probe with a NMR-chip as described above, wherein the NMR-chip is aligned along a static magnetic field in z-direction, which is produced from the superconducting magnet in operation.", "[0035] Further advantages can be extracted from the description and the enclosed drawing.", "The features mentioned above and below can be used in accordance with the invention either individually or collectively in any combination.", "The embodiments mentioned are not to be understood as exhaustive enumeration but rather have exemplary character for the description of the invention.", "[0036] The invention is shown in the drawing.", "BRIEF DESCRIPTION OF THE DRAWING [0037] FIG. 1 shows optimal B0 and B1 field profiles (theoretical);", "[0038] FIG. 2 shows a cut-out of a schematic top view of an inventive flow-through microfluidic NMR-chip;", "[0039] FIG. 3 shows a schematic top view of an inventive flow-through microfluidic NMR-chip;", "[0040] FIG. 4 shows a schematic perspective view of an inventive flow-through microfluidic NMR-chip;", "[0041] FIG. 5 shows the B0 profile produced by an elongated sample chamber and a B1 profiles for a rectangular coil with and without shielding plates;", "[0042] FIG. 6 shows a schematic top view of an inventive flow-through microfluidic NMR-chip with integrated shielding plates;", "[0043] FIG. 7 shows a B0 distortion produced by a cross-wire section of a rectangular coil with and without magnetic susceptibility compensation;", "[0044] FIG. 8 shows the principle of susceptibility compensation using layered conductors;", "[0045] FIG. 9 shows a schematic perspective view an inventive flow-through microfluidic NMR-chip with an integrated Helmholtz microcoil arrangement;", "[0046] FIG. 10 shows a schematic top view of an inventive flow-through microfluidic NMR-chip comprising two inductively decoupled coils, one of them forming a butterfly coil geometry;", "[0047] FIG. 11 shows a schematic cross sectional view of the NMR-chip according to FIG. 10 ;", "[0048] FIG. 12 shows a schematic top view of an inventive flow-through microfluidic NMR-chip comprising two sample inlets upstream of the sample chamber;", "[0049] FIG. 13 shows a schematic a schematic top view of an inventive NMR-apparatus for spectrometer applications with an inventive NMR-chip;", "[0050] FIG. 14 shows a proton NMR spectrum of sucrose derived by a preferred embodiment of the inventive NMR-chip;", "[0051] FIG. 15 shows the nutation curve illustrating B1 homogeneity for the configuration used for obtaining the NMR-spectrum of FIG. 14 ;", "[0052] FIG. 16 shows a Heteronuclear Multiple Quantum Correlation (HMQC) spectrum measured with a NMR-chip shown in FIG. 10 and FIG. 11 .", "[0053] FIG. 17 a shows a circular coil geometry combined with a spherical sample chamber according to [5] (PRIOR ART);", "[0054] FIG. 17 b shows a straight channel in line with the static magnetic field combined with a multi-turn circular microcoil placed in the central region of the channel according to [6] (PRIOR ART);", "[0055] FIG. 17 c shows a rectangular coil geometry combined with a rectangular cavity of dimensions smaller than the coil according to [3] (PRIOR ART);", "[0056] FIG. 18 a shows the spectral resolution on a sucrose sample with a configuration according to [4] (PRIOR ART);", "and [0057] FIG. 18 b shows the nutation curve illustrating B1 homogeneity for a configuration according to [4] (PRIOR ART);", "DESCRIPTION OF THE PREFERRED EMBODIMENT [0058] FIG. 1 shows an ideal B0 static magnetic field profile 3 and B1 RF field profile 4 to be achieved within a sample to be examined.", "With the inventive NMR-chip these ideal profiles can be approximated and thus good performance with microfluidic NMR-chips can be achieved.", "[0059] A cut-out of the inventive NMR-chip is disclosed in FIG. 2 .", "A sample chamber 2 within a planar substrate 5 is elongated and has walls which run parallel to the z-direction.", "A rectangular planar coil 1 is provided having conductor sections 11 , which also run parallel to the z-direction, in the sense that projection of 11 on the z-axis is larger than the projection on the y-axis.", "The dashed lines show one of the possible deviations from the straight lines.", "For simplicity and without loss of generality we will only show the case of straight lines in the following figures.", "Closing sections of the coil 1 and of the sample chamber 2 are not represented in FIG. 2 on purpose for they will be discussed later.", "During use of the inventive NMR-chip within a NMR-spectrometer the static magnetic field B 0 is aligned in z-direction (see FIG. 3 ).", "Since the elongated sample chamber 2 is also aligned in z-direction B0 distortion are minimized within the central part of the sample chamber 2 .", "Conductor sections 11 do not produce significant distortion of the B0 field within the sample volume, and produce a homogeneous B1 field along the z-axis.", "[0060] FIG. 3 and FIG. 4 show a top view and a perspective view respectively of a preferred embodiment of the invention derived from the configuration shown in FIG. 2 .", "[0061] The substrate 5 has a length L 1 , a width W 1 , is preferable made from a glass material or quartz.", "It comprises two substrate parts 51 , 52 with thicknesses t 1 , t 2 which are bonded together.", "An elongated channel is etched on the lower surface of a first planar substrate part 51 and on the upper surface of the second substrate part 52 .", "The sample chamber 2 can also be formed by etching only one of the substrate parts 51 , 52 , as shown in FIG. 11 .", "The dimensions of the inventive NMR-chip are mainly defined by the dimensions of the substrate: Substrate surface (L 1 *W 1 )<15 cm 2 Substrate length 5 mm<L 1 <50 mm Substrate width 3 mm<W 1 <30 mm (W 1 <L 1 ) Substrate thickness 100 μm<(t 1 +t 2 )<2 mm, [0066] The NMR sample chamber 2 is formed by the cavities etched in the first 51 and second planar glass substrate part 52 , by assembling the substrate parts 51 , 52 onto each other.", "The sample chamber 2 has a finite length L 2 , a width W 2 , and a channel depth d 1 , preferable with the following dimensions: Sample chamber length 200 μm<L 2 <16 mm Sample chamber width 50 μm<W 2 <2 mm (8*W 2 <L 2 ) Channel depth 50 μm<(2*d 1 )<1 mm Sample chamber volume 4 nanoliter<V 2 <30 microliter [0071] The coil 1 has closing cross-wire sections 12 perpendicular to the z-axis.", "The length L 3 of the coil 1 is greater than its width W 3 , thereby causing an elongated shape of the coil 1 .", "Preferably coil 1 has a rectangular shape, but can also have another elongated shape, such as an ellipsoid.", "In case coil 1 is used as a proton coil (i.e. for exciting 1 H-nuclei) its wires are advantageously made of copper (Cu), silver (Ag) or gold (Au).", "For optional compensation of magnetic susceptibility other materials may be added.", "Both single and multiple turn coils are suitable for NMR-spectroscopy purposes.", "The preferred dimensions for a rectangular coil 1 are the following: Coil wire thickness 5 μm<h 1 <50 μm (h 1 >2*skin depth) Coil wire width 10 μm<h 2 <800 μm Coil surface (L 3 *W 3 )<40 mm2 Coil length 100 μm<L 3 <10 mm (1.5*L 3 <L 2 ) Coil width 100 μm<W 3 <5 mm (W 2 <W 3 <2*W 2 and W 3 <L 3 ).", "[0077] FIG. 5 shows a realistic B0 field profile 31 and a B1 field profile 41 corresponding to the embodiment disclosed in FIG. 3 .", "The finite length L 2 of the sample chamber 2 produces a B0 distortion 31 proportional to z 2 .", "However, for larger coil (in millimeter range) this z 2 distortion can be compensated using standard room-temperature shims of commercially available magnets.", "For small coils (100 μm, range) this distortion can not be shimmed and it is important that the sample chamber exceeds the length of the coil.", "The B1 field profile 41 produced by the coil 1 resembles the ideal rectangular field profile 4 , apart from negative field regions caused by the coil cross-wires 12 .", "[0078] An arrangement allowing one to eliminate those negative B1 field values produced by the coil cross-wires 12 is disclosed in FIG. 6 .", "The NMR-chip 5 comprises integrated shielding plates 6 , which are placed above and below the coil 1 in z-direction in order to cover those parts of the sample chamber 2 which are not covered by the coil 1 therewith preventing the RF field B 1 to penetrate the sample in regions external from the coil 1 .", "The coil 1 and the shielding plates 6 are preferably arranged within the same plane.", "The corresponding B1 field profile 42 is illustrated in FIG. 5 , and becomes very close to the ideal rectangular field profile 4 of FIG. 1 .", "The shielding plates may comprise copper layers which act as an eddy current shielding.", "Said copper shielding plates 6 may show a thickness of 10 μm (at least twice the skin depth at the working frequency and preferably equal to the coil thickness h 1 ) and a length L s of 3 mm (Ls>(L 2 −L 3 )/2).", "The width W s of the shielding plates 6 should be greater than the width W 2 of the sample chamber.", "[0079] In addition to B0 distortion 31 produced by the finite length L 2 of the sample chamber, a B0 distortion 32 produced by diamagnetic coil cross-wires 12 is illustrated in FIG. 7 .", "Such a B0 distortion 32 is difficult to shim and limits the overall spectral resolution at high static field B 0 .", "The distortion 32 of the static field B 0 can be further reduced by adding a compensating layer 122 between the substrate 5 and the coil conductor 121 of the coil cross wire 12 as shown in FIG. 8 .", "The susceptibility of the compensating layer 122 has to have the opposite sign as the susceptibility of the coil conductor 121 .", "The effect of such a compensating layer 122 on B0 distortion is illustrated in FIG. 7 (profile 33 ).", "One can see that the B0 distortion 32 produced by diamagnetic coil cross-wires 12 is distinctly reduced.", "[0080] An embodiment of the invention featuring two coils 1 , each on one external surfaces of the substrate 5 is disclosed in FIG. 9 .", "The coils 1 are connected to form a Helmholtz arrangement 7 .", "A high B1 homogeneity performance can be obtained when the coil widths W 3 are approximately equal to twice the substrate thickness (t 1 +t 2 ).", "[0081] FIG. 10 discloses an embodiment of a flow-through microfluidic NMR-chip 5 comprising two inductively decoupled coils 1 , 1 ′, one of them forming a butterfly coil geometry 1 ′.", "A cross-section view of this embodiment is illustrated in FIG. 11 .", "Coil 1 produces a RF field B 1 mainly along the x-axis within the sample chamber 2 and is preferably tuned to proton frequency.", "Coil 1 ′ produces an RF field B 2 mainly along the y-axis within the sample chamber 2 and is preferably tuned to lower frequency nuclei, for example carbon.", "The two coils 1 , 1 ′ can be produced by photolithography on the same surface of the substrate 5 and are separated by an electrically insulating layer 8 as shown in FIG. 11 .", "[0082] An embodiment of the present invention comprising two sample inlets 21 a , 21 b upstream of the sample chamber 2 is shown in FIG. 12 .", "Such a NMR-chip allows one to introduce two different fluid samples A, B, one through each sample inlet 21 a , 21 b , and to monitor interaction between sample A and sample B by NMR while flowing the samples through the NMR-chip to an outlet 22 .", "[0083] FIG. 13 shows inventive microfluidic NMR-chip arranged within a superconducting magnet arrangement for use with a NMR-spectrometer 13 .", "The NMR-chip is mounted on a probe 14 .", "The end portions of the sample chamber 2 are connected to an inlet capillary 9 and an outlet capillary 10 respectively.", "The probe 14 is placed within a super-conducting magnet 15 so that the elongated sample chamber 2 along z-axis is aligned with the static field B 0 of the superconducting magnet 15 .", "A sample can be introduced into the NMR-chip through a sample port 16 via the inlet capillary 9 and can be taken out of the sample chamber through an outlet port 17 via the outlet capillary 10 .", "[0084] Compared to prior art, the present invention improves NMR detection performance within microfluidic NMR-chips in many respects.", "These improvements are illustrated for two examples of possible embodiments.", "[0085] The first example deals with a flow-through microfluidic NMR-chip with an integrated Helmholtz microcoil as shown in FIG. 9 .", "The microfluidic NMR-chip was formed by bonding together two glass substrates 51 and 52 with thickness t 1 =t 2 =500 μm, each comprising an etched half-channel.", "The resulting substrate 5 thickness was 1 mm.", "The sample chamber depth d 1 was 300 μm, width W 2 was 1.2 mm and length L 2 was 11.2 mm.", "Rectangular coils were patterned by photolithography on both surfaces of the NMR-chip.", "The coil width W 3 was 2 mm and the length L 3 was 2.8 mm.", "The coil wire was made of copper with a width 80 μm and thickness h 1 =15 μm.", "The active volume was 1 μL while the total volume in the NMR-chip was 4.8 μL.", "The glass NMR-chip dimensions were 22 mm (L 1 )×10 mm (W 1 ).", "[0086] FIG. 14 illustrates a proton NMR spectrum of sucrose acquired at 300 MHz using this example embodiment.", "The sample was 50 mM of sucrose in D 2 O. The splitting measured on the anomeric proton was 20%.", "The Signal-to-Noise(=SNR) value measured on the anomeric proton was 90 after 480 scans (with 0.7 Hz line broadening), corresponding to an SNR of 4.1/scan.", "This spectrum should be compared to the prior art spectrum of FIG. 18 a .", "Note that although the magnetic susceptibility of the copper wires was not compensated in this example, the resulting spectral resolution was excellent as a result of the inventive configuration.", "[0087] This example embodiment also provided excellent B1 homogeneity performance as illustrated in FIG. 15 .", "The excitation power was 16 W and the pulse duration was increased by increments of 1 μs, with a starting value of 2 μs.", "The signal amplitudes measured for a 450° and 810° pulse were respectively 96% and 86% of that obtained for a 90° pulse.", "This constitutes a large improvement compared to prior art performance illustrated in FIG. 18 b. [0088] The second example deals with another embodiment of the present invention comprising two magnetically decoupled coils tuned to two different frequencies, as shown in FIG. 10 and FIG. 11 .", "A channel with a depth of 150 μm was etched on the bottom surface of a 500 μm thick glass substrate 51 .", "This first substrate was bonded with a second 500 μm thick substrate 52 to form a 1 mm thick microfluidic substrate 5 .", "The sample chamber depth d 1 was 150 μm, width W 2 was 1.2 mm and length L 2 was 11.2 mm.", "The total NMR-chip sample volume was 2.3 μL, including inlet and outlet channels.", "The glass NMR-chip dimensions were 22 mm (L 1 )×10 mm (W 1 ).", "A rectangular coil 1 and a butterfly coil 1 ′ were microfabricated on the top surface of the substrate 5 , as shown in FIG. 10 and FIG. 11 .", "The width W 3 of the rectangular coil 1 was W 3 =2 mm and the length L 3 was L 3 =2.8 mm.", "Thus, the active sample volume was 500 nL.", "The wire forming the coil 1 was copper with a width of 80 μm and thickness h 1 of 10 μm.", "The rectangular microcoil 1 was doubled tuned to proton at 500 MHz and deuterium at 76 MHz.", "The butterfly microcoil 1 ′ comprised 8 straight copper conductor sections producing an RF field B 2 parallel to the substrate surface within the sample chamber.", "The wire width for the butterfly coil 1 ′ was 40 μm with 30 μm spacing between turns and thickness was 15 μm.", "The wires of the butterfly coil 1 ′ were electrically insulated from the wires of the rectangular coil 1 using a patterned polymer layer 8 .", "The butterfly coil 1 ′ was tuned to 125 MHz for carbon observe or decoupling.", "The measured decoupling between 13C and 1H channels after building the tuning and matching circuit was −26.5 dB at 500 MHz.", "This decoupling value was appropriate to perform multinuclei NMR experiments.", "FIG. 16 illustrates an HMQC spectrum acquired at 500 MHz using this example embodiment.", "The sample was 1M 13CH3OH+10% H 2 O+0.2 mg GdGl3/mL in D 2 O. LIST OF REFERENCE SIGNS [0000] A Sample B Sample B 0 Static magnetic field B 1 RF field d 1 Channel depth of the sample chamber h 1 Wire thickness of microcoil h 2 Wire width of microcoil L 1 Length of substrate (extension in z-direction) L 2 Length of sample chamber (extension in z-direction) L 3 Length of microcoil (extension in z-direction) L s Length of shielding plates (extension in z-direction) t 1 Thickness of first substrate part (extension in x-direction) t 2 Thickness of second substrate part (extension in x-direction) W 1 Width of substrate (extension in y-direction) W 2 Width of sample chamber (extension in y-direction) W 3 Width of microcoil (extension in y-direction)y W s Width of shielding plates (extension in y-direction) 1 ′ Butterfly microcoil 1 Rectangular planar microcoil 2 Sample chamber 3 Ideal profile of the static magnetic field B 0 4 Ideal profile of the RF magnetic field B 1 5 Microfluidic substrate 6 RF shielding plate 7 Helmholtz microcoil 8 Electrically insulating layer 9 Inlet capillary 10 Outlet capillary 11 Straight conductor sections 12 Microcoil cross-wire 13 NMR-spectrometer 14 Probe head 15 Superconducting magnet 16 Inlet port 17 Outlet port 31 Profile of the static magnetic field B 0 with z 2 distortion 32 Profile of the static magnetic field B 0 distortion introduced by diamagnetic cross-wires 33 Profile of the static magnetic field B 0 distortion introduced by cross-wires with susceptibility compensation 41 Profile of the RF magnetic field produced by a rectangular coil 42 Profile of the RF magnetic field produced by a rectangular coil with shielding plates 51 First planar substrate part 52 Second planar substrate part 100 Planar NMR microcoil (circular geometry) 101 Planar NMR microcoil (circular geometry) 102 Planar NMR microcoil (rectangular geometry) 121 Diamagnetic conductor layer 121 Paramagnetic layer 21 a Sample inlet 21 b Sample inlet 22 Sample outlet 200 Sample chamber (spherical geometry) 201 Channel 202 Closed cavity [1] U.S. Pat. No. 5,654,636 [2] U.S. Pat. No. 6,194,900 [3] Syms et al.", ", J. Micromech.", "Microeng.", "15 (2005), S1-S9 [4] Massin et al.", ", J Mag Res, 164, (2003), 242-255 [5] Walton et al.", ", Anal.", "Chem.", ", 75 (2003), 5030-5036 [6] Wensink et al.", ", Lab Chip, 5, (2005), 280-284" ]
FIELD OF THE INVENTION The present invention relates to an apparatus for positioning, in the course of manufacture of a photoreceptor drum for electrophotography use, a cylindrical drum of the for coating by a coating solution. BACKGROUND OF THE INVENTION In the course of manufacture of a photoreceptor drum of an organic photoconductor type that is to be used as a photoreceptor in an electrophotographic apparatus, a photosensitive coating solution is coated on a cylindrical drum base body of the photoreceptor. When the cylindrical drum base body is coated, it is necessary that slide hoppers and the like are positioned at predetermined locations around the cylindrical drum and that the clearance between the cylindrical drum and each slide hopper in the radial direction on a sectional circle of the cylindrical drum is adjusted to be constant. In this case, the deviation of the cylindrical drum by only 0.1 mm in the radial direction can cause a great difference in the thickness of a coated layer because a coated layer is extremely thin in its necessary thickness. It is generally known that such difference in thickness of a coated layer causes various kinds of troubles such as a change of a charged amount in the radial direction of the cylindrical drum, unevenness of sensitivity and a change of residual potential. Therefore, it is very important to position the cylindrical drum accurately. Heretofore, as drum-positioning methods of this kind, there is known a method wherein a drum is fed continuously through coating heads being touched by position-regulating rollers provided around the drum. Alternatively, a drum is fed continuously through coating heads being touched by a group of plural driving rollers provided in the transport direction. At the same time, the relation in terms of location between an external peripheral surface of the drum and the coating head is adjusted while the coating head is moved horizontally through rollers. These methods are similar to those disclosed in Japanese Patent Publication Open to Public Inspection Nos. 60-50537 and 60-95546 (hereinafter referred to as Japanese Patent O.P.I. Publication]. In all of the conventional apparatuses, however, positioning is conducted with position-regulating rollers or with a group of driving rollers all of them contacting directly a drum. Therefore, the drum is scratched, which is a disadvantage. It is generally known that the scratch on the drum causes electrophotographic characteristics to be worsened. On the other hand, in the apparatus disclosed in the latter publication, it is essential that the position of a drum is regulated and the position of each coating head is adjusted, but when the coating head is made to be slidable, the coating head tends to be deviated against the drum, and it is particularly difficult to keep the drum and the coating head coaxial. SUMMARY OF THE INVENTION A primary subject to be solved by the invention is how to position a drum without causing the drum to be scratched. Further, when positioning a drum, the drum is required to be positioned, without being positioned by a single point in its axial direction, in a way so as to prevent the movement of the slanted drum and to thereby keep constantly a uniform clearance between the drum and a coating head. This is because a drum, when it is fed aslant, tends to move aslant in its axial direction even when the outer circumferential surface of the drum is controlled in terms of position. This in turn results in a phenomenon that the drum hits a supporting member or the drum moves without keeping a uniform clearance between the drum and the coating head, causing scratching. Further, when drum 1 is positioned by air pressure generated from air-jetting nozzle 3 that is arranged horizontally in a process for coating a light-sensitive solution from a coating head while moving drums 1 by coupling them in succession, a part of jetted air sometimes goes up after hitting the outer surface of a drum 1 and flows toward coating head 2 to pass upward through the clearance between the outer surface of a drum 1 and coating head 2. In this case, a coating mottle or a coating defect is caused, resulting in a failure in smooth coating. An object of the invention, therefore, is to position a drum without causing any scratch on the drum and to eliminate an adverse effect on coating conducted by a coating head. The aforesaid objects can be achieved by a photoreceptor-drum-positioning apparatus for positioning a cylindrical drum base body of a photoreceptor drum when a coating solution is coated on an external surface of said cylindrical drum base body in the course of manufacture of the photoreceptor drum, wherein there is provided a blowing means that jets a fluid against a portion not yet coated or a portion already coated on said cylindrical drum base body and thereby positions the cylindrical drum base body by means of pressure of the fluid. This jetting means is provided at a single location on the same circumference of a circle or a plurality of jetting means are provided at some intervals in the direction of an axis of a drum base body. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing the outline of a first example of a photoreceptor-drum-positioning apparatus related to the invention. FIG. 2 is a horizontal sectional view of the first example. FIG. 3 is a horizontal sectional view of a second example. FIG. 4 is a horizontal sectional view of a third example. FIG. 5 is a horizontal sectional view of a fourth example. FIG. 6 is a horizontal sectional view of a fifth example. FIG. 7 is a longitudinal sectional view of an example of a coating head. FIG. 8 is an example of a drum positioning apparatus wherein the nozzle orifices are inclined at angles deviated from a radial direction of the drum. FIG. 9 is an example of a drum positioning apparatus wherein the orifice of each nozzle is inclined downward at an angle to the drum axis. FIG. 10 is an example of a drum positioning apparatus wherein two sets of nozzles are spaced axially along the drum path. DETAILED DESCRIPTION OF THE INVENTION In the present invention, a cylindrical drum is positioned by fluid pressure which is generated when a fluid is jetted against an external surface of the cylindrical drum. Namely, when a fluid such as, for example, air is jetted against the peripheral surface of the drum, the jetting pressure neutralizes the position of the drum, thereby positioning the drum at a predetermined location thereby preventing the drum from being scratched because nothing touches the drum mechanically. In addition the drum may be positioned through a plurality of points in the direction of an axis of the drum so that, it is possible to hold the drum in parallel with an axis of a coating head without any inclination of the drum axis, thereby preventing the phenomena whereby the drum hits the coating head and causes an uneven clearance in the circumferential direction. Thus a uniform coating thickness is achieved. EXAMPLES The invention will be explained in detail, referring to the examples. FIG. 1 and FIG. 2 show the first example, and the numeral 1 is a drum base body in the shape of, for example, a hollow cylinder which can be elevated continuously by an unillustrated conveyance means such as, for example, a cylinder that pushes up the bottom surface of the drum base body. The numeral 2 is a coating head in the shape of a ring for coating a photosensitive liquid on an external surface of drum base body 1, and it is provided fixedly for coating a photosensitive liquid by jetting the liquid continuously from an outlet formed on an internal side of the ring while drum base body 1 is ascending. As a coating head that is a coating means used for the invention, what is disclosed in Japanese Patent O.P.I. Publication No. 189061/1983 or in Japanese Patent O.P.I. Publication No. 50537/1985 can be used if it satisfies the condition that it be located around an external surface of drum base body 1 so that it covers the drum base body and the further condition that it have a basic arrangement for coating a coating solution on an external surface of drum base body 1. An example of the coating head mentioned above is shown in FIG. 7. This coating head 2 is a coating head of a slide hopper type. On coating head 2, there is formed horizontally the narrow coating solution-distributing slit 22 having thereon coating solution outlet 21 facing the drum base body 1 side. The slit 22 is connected to solution-pool header 23, and the solution-pool header 23 is arranged so that photosensitive liquid L is fed to it by a force-feeding pump [not shown]. On the other hand, there is formed solution-sliding surface 25 below the coating solution outlet 21 of slit 22 so that the solution-sliding surface inclines continuously and terminates slightly larger in dimension than the outside diameter of drum base body 1. Further, lip-shaped portion 26 is formed so that it extends downward from the lower end of solution-sliding surface 25. When such coating head 2 is used, photosensitive liquid L is ejected while drum base body 1 is elevated from slit 22 and from coating solution outlet 21 so that the liquid flows down along solution-sliding surface 25. Photosensitive liquid L arriving at lip-shaped portion 26 is coated on the external surface of drum base body 1 at a thickness equivalent to the clearance between lip-shaped portion 26 and drum base body 1. For the purpose of feeding drum base body 1 coaxial with such coating head 2, there is provided a blowing means for positioning drum base wherein body 1 fluid pressure is utilized. In the first example shown in FIGS. 1 and 2, air-ejecting nozzles 3 are arranged horizontally to face the center axis of drum base body 1 at an interval angle of 120 0 so that their tips are equally away, in distance, from the center axis of coating head 2, and so that each air-ejecting nozzle 3 is connected to common ring-shaped header 4. This ring-shaped header 4 is arranged so that it receives high-pressure air from compressor 5, and high-pressure air led to ring-shaped header 4 is sprayed at high speed, with constant ejecting amount and ejecting pressure, toward an external surface of drum base body 1 from each of ejecting-nozzles 3. As a result, drum base body 1 is positioned with its axis being coaxial with the center axis of coating head 2. Therefore, photosensitive liquid coming from coating head 2 can be coated on the external surface of drum base body 1 at a uniform thickness The inner diameter of the nozzles is not more than 10.0 mm and not less than 1.0 mm, and the clearance between the nozzles and the drum is not more than 1.00 mm and not less than 0.02 mm. Furthermore, in addition to a set of jetting means having jetting nozzles 3 provided at a certain location on drum 1, at least two of jetting means may be provided at other locations along the axial direction of the drum, for example, as shown in FIG. 10. In these other sets of jetting means which have the same structure, air is jetted from each jetting nozzle by means of a common compressor. In this case, it is possible to adjust an amount or pressure of jetted air by means of a regulating valve 10, as shown in FIG. 5, so that each set of jetting means may differ from others in terms of an amount or pressure of jetted air. It is further possible to make an air jetting position of a nozzle of each set of jetting means to be different from others by 60°, for example. It is also possible to make the direction of air jetted from an orifice of each nozzle 3 to be inclined downward by an inclination angle up to 30°, for example, as shown in FIG. 9. Each nozzle 3 is arranged so that it may be supplied with high-pressure air from an unillustrated compressor. Air jetted from nozzle 3 in this case, after hitting the outer surface of drum base body 1, does not go upward but does go downward without fail so as not to adversely affect the layer of light-sensitive solution coated by coating head 2, thereby preventing any coating defect. As long as the direction of jetting from nozzle 3 is inclined, air, after hitting, never goes up. It is also possible to have an arrangement wherein a continuous slit 3 is provided on a ring-shaped blowing, means so that the continuous slit may face drum base body 1 and so that the direction of jetting from the slit is inclined downward. FIG. 6, for example, shows a case where the fluid outlet is a ring-shaped slit, located underneath the coater. Further, although each nozzle 3 is positioned horizontally, it is also possible to have an arrangement wherein each direction of air jetting has a deviation without pointing to the center of drum base body 1 and is inclined by a certain angle from the radial direction from the center of the drum base body, for example, as shown in FIG. 8. In this case, air jetted from nozzle 3, after it hits drum base body 1, goes mostly horizontally and never goes up. FIG. 3 shows the second example wherein four air-ejecting nozzles 3 are provided around drum base body 1 with an angular interval of 90°. The number of nozzles 3 is not limited as shown in this example. FIG. 4 shows a case where the outlet nozzle 3 is shaped along the curve of the drum surface. As a photosensitive liquid, it is possible to use inorganic photosensitive materials such as zinc oxide and cadmium sulfide as well as organic photosensitive materials such as polyvinylcarbazole and trinitrofluorene both dispersed in a high molecular binder. In addition, it is also possible to use a photosensitive layer of a function-separated type wherein a charge generating layer and a charge transport layer are laminated, so as to meet the recent demand for high sensitivity and improved durability. For example, a charge generating layer is obtained by dispersing azo pigment, quinone pigment perylene pigment, phthalocyanine pigment or anthanthrone pigment in a high molecular binder such as polycarbonate, and a charge transport layer is obtained by dispersing polycyclic aromatic compound or a nitrogen-containing cyclic compound in a high molecular binder. The thickness of a charge generating layer is 0.01-10 μm and preferably is 0.05-5 μm, while that of a charge transport layer is preferably 5-30 μm. The range of viscosity of photosensitive liquid is 0.5-700 cp and it is preferably 1-500 cp. Further, as a hollow drum for electrophotography use, aluminum, stainless steel or plastic on which a conductive layer is formed can be used. In addition to that, it is also possible to use a hollow drum wherein a subbing layer and a charge generating layer are formed in advance. As stated above, the invention has an advantage in that a drum can be positioned accurately without being touched and thereby without being scratched. The invention has a further advantage in that dust particles sticking to the drum are removed by sprayed air, thereby improving the coating efficiency.
A position setting apparatus for positioning a drum so that it may be uniformly coated with a photosensitive coating liquid to produce a photoreceptor, wherein the position of the drum is set by centripetally blowing a pressurized fluid from a fluid outlet means directly against the drum. The drum is positioned by the balance of the pressure of the blown fluid, and the surface of the drum is thereby protected from scratching as no mechanical device is required to touch the drum during positioning.
Provide a concise summary of the essential information conveyed in the given context.
[ "FIELD OF THE INVENTION The present invention relates to an apparatus for positioning, in the course of manufacture of a photoreceptor drum for electrophotography use, a cylindrical drum of the for coating by a coating solution.", "BACKGROUND OF THE INVENTION In the course of manufacture of a photoreceptor drum of an organic photoconductor type that is to be used as a photoreceptor in an electrophotographic apparatus, a photosensitive coating solution is coated on a cylindrical drum base body of the photoreceptor.", "When the cylindrical drum base body is coated, it is necessary that slide hoppers and the like are positioned at predetermined locations around the cylindrical drum and that the clearance between the cylindrical drum and each slide hopper in the radial direction on a sectional circle of the cylindrical drum is adjusted to be constant.", "In this case, the deviation of the cylindrical drum by only 0.1 mm in the radial direction can cause a great difference in the thickness of a coated layer because a coated layer is extremely thin in its necessary thickness.", "It is generally known that such difference in thickness of a coated layer causes various kinds of troubles such as a change of a charged amount in the radial direction of the cylindrical drum, unevenness of sensitivity and a change of residual potential.", "Therefore, it is very important to position the cylindrical drum accurately.", "Heretofore, as drum-positioning methods of this kind, there is known a method wherein a drum is fed continuously through coating heads being touched by position-regulating rollers provided around the drum.", "Alternatively, a drum is fed continuously through coating heads being touched by a group of plural driving rollers provided in the transport direction.", "At the same time, the relation in terms of location between an external peripheral surface of the drum and the coating head is adjusted while the coating head is moved horizontally through rollers.", "These methods are similar to those disclosed in Japanese Patent Publication Open to Public Inspection Nos. 60-50537 and 60-95546 (hereinafter referred to as Japanese Patent O.P.I. Publication].", "In all of the conventional apparatuses, however, positioning is conducted with position-regulating rollers or with a group of driving rollers all of them contacting directly a drum.", "Therefore, the drum is scratched, which is a disadvantage.", "It is generally known that the scratch on the drum causes electrophotographic characteristics to be worsened.", "On the other hand, in the apparatus disclosed in the latter publication, it is essential that the position of a drum is regulated and the position of each coating head is adjusted, but when the coating head is made to be slidable, the coating head tends to be deviated against the drum, and it is particularly difficult to keep the drum and the coating head coaxial.", "SUMMARY OF THE INVENTION A primary subject to be solved by the invention is how to position a drum without causing the drum to be scratched.", "Further, when positioning a drum, the drum is required to be positioned, without being positioned by a single point in its axial direction, in a way so as to prevent the movement of the slanted drum and to thereby keep constantly a uniform clearance between the drum and a coating head.", "This is because a drum, when it is fed aslant, tends to move aslant in its axial direction even when the outer circumferential surface of the drum is controlled in terms of position.", "This in turn results in a phenomenon that the drum hits a supporting member or the drum moves without keeping a uniform clearance between the drum and the coating head, causing scratching.", "Further, when drum 1 is positioned by air pressure generated from air-jetting nozzle 3 that is arranged horizontally in a process for coating a light-sensitive solution from a coating head while moving drums 1 by coupling them in succession, a part of jetted air sometimes goes up after hitting the outer surface of a drum 1 and flows toward coating head 2 to pass upward through the clearance between the outer surface of a drum 1 and coating head 2.", "In this case, a coating mottle or a coating defect is caused, resulting in a failure in smooth coating.", "An object of the invention, therefore, is to position a drum without causing any scratch on the drum and to eliminate an adverse effect on coating conducted by a coating head.", "The aforesaid objects can be achieved by a photoreceptor-drum-positioning apparatus for positioning a cylindrical drum base body of a photoreceptor drum when a coating solution is coated on an external surface of said cylindrical drum base body in the course of manufacture of the photoreceptor drum, wherein there is provided a blowing means that jets a fluid against a portion not yet coated or a portion already coated on said cylindrical drum base body and thereby positions the cylindrical drum base body by means of pressure of the fluid.", "This jetting means is provided at a single location on the same circumference of a circle or a plurality of jetting means are provided at some intervals in the direction of an axis of a drum base body.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing the outline of a first example of a photoreceptor-drum-positioning apparatus related to the invention.", "FIG. 2 is a horizontal sectional view of the first example.", "FIG. 3 is a horizontal sectional view of a second example.", "FIG. 4 is a horizontal sectional view of a third example.", "FIG. 5 is a horizontal sectional view of a fourth example.", "FIG. 6 is a horizontal sectional view of a fifth example.", "FIG. 7 is a longitudinal sectional view of an example of a coating head.", "FIG. 8 is an example of a drum positioning apparatus wherein the nozzle orifices are inclined at angles deviated from a radial direction of the drum.", "FIG. 9 is an example of a drum positioning apparatus wherein the orifice of each nozzle is inclined downward at an angle to the drum axis.", "FIG. 10 is an example of a drum positioning apparatus wherein two sets of nozzles are spaced axially along the drum path.", "DETAILED DESCRIPTION OF THE INVENTION In the present invention, a cylindrical drum is positioned by fluid pressure which is generated when a fluid is jetted against an external surface of the cylindrical drum.", "Namely, when a fluid such as, for example, air is jetted against the peripheral surface of the drum, the jetting pressure neutralizes the position of the drum, thereby positioning the drum at a predetermined location thereby preventing the drum from being scratched because nothing touches the drum mechanically.", "In addition the drum may be positioned through a plurality of points in the direction of an axis of the drum so that, it is possible to hold the drum in parallel with an axis of a coating head without any inclination of the drum axis, thereby preventing the phenomena whereby the drum hits the coating head and causes an uneven clearance in the circumferential direction.", "Thus a uniform coating thickness is achieved.", "EXAMPLES The invention will be explained in detail, referring to the examples.", "FIG. 1 and FIG. 2 show the first example, and the numeral 1 is a drum base body in the shape of, for example, a hollow cylinder which can be elevated continuously by an unillustrated conveyance means such as, for example, a cylinder that pushes up the bottom surface of the drum base body.", "The numeral 2 is a coating head in the shape of a ring for coating a photosensitive liquid on an external surface of drum base body 1, and it is provided fixedly for coating a photosensitive liquid by jetting the liquid continuously from an outlet formed on an internal side of the ring while drum base body 1 is ascending.", "As a coating head that is a coating means used for the invention, what is disclosed in Japanese Patent O.P.I. Publication No. 189061/1983 or in Japanese Patent O.P.I. Publication No. 50537/1985 can be used if it satisfies the condition that it be located around an external surface of drum base body 1 so that it covers the drum base body and the further condition that it have a basic arrangement for coating a coating solution on an external surface of drum base body 1.", "An example of the coating head mentioned above is shown in FIG. 7. This coating head 2 is a coating head of a slide hopper type.", "On coating head 2, there is formed horizontally the narrow coating solution-distributing slit 22 having thereon coating solution outlet 21 facing the drum base body 1 side.", "The slit 22 is connected to solution-pool header 23, and the solution-pool header 23 is arranged so that photosensitive liquid L is fed to it by a force-feeding pump [not shown].", "On the other hand, there is formed solution-sliding surface 25 below the coating solution outlet 21 of slit 22 so that the solution-sliding surface inclines continuously and terminates slightly larger in dimension than the outside diameter of drum base body 1.", "Further, lip-shaped portion 26 is formed so that it extends downward from the lower end of solution-sliding surface 25.", "When such coating head 2 is used, photosensitive liquid L is ejected while drum base body 1 is elevated from slit 22 and from coating solution outlet 21 so that the liquid flows down along solution-sliding surface 25.", "Photosensitive liquid L arriving at lip-shaped portion 26 is coated on the external surface of drum base body 1 at a thickness equivalent to the clearance between lip-shaped portion 26 and drum base body 1.", "For the purpose of feeding drum base body 1 coaxial with such coating head 2, there is provided a blowing means for positioning drum base wherein body 1 fluid pressure is utilized.", "In the first example shown in FIGS. 1 and 2, air-ejecting nozzles 3 are arranged horizontally to face the center axis of drum base body 1 at an interval angle of 120 0 so that their tips are equally away, in distance, from the center axis of coating head 2, and so that each air-ejecting nozzle 3 is connected to common ring-shaped header 4.", "This ring-shaped header 4 is arranged so that it receives high-pressure air from compressor 5, and high-pressure air led to ring-shaped header 4 is sprayed at high speed, with constant ejecting amount and ejecting pressure, toward an external surface of drum base body 1 from each of ejecting-nozzles 3.", "As a result, drum base body 1 is positioned with its axis being coaxial with the center axis of coating head 2.", "Therefore, photosensitive liquid coming from coating head 2 can be coated on the external surface of drum base body 1 at a uniform thickness The inner diameter of the nozzles is not more than 10.0 mm and not less than 1.0 mm, and the clearance between the nozzles and the drum is not more than 1.00 mm and not less than 0.02 mm.", "Furthermore, in addition to a set of jetting means having jetting nozzles 3 provided at a certain location on drum 1, at least two of jetting means may be provided at other locations along the axial direction of the drum, for example, as shown in FIG. 10.", "In these other sets of jetting means which have the same structure, air is jetted from each jetting nozzle by means of a common compressor.", "In this case, it is possible to adjust an amount or pressure of jetted air by means of a regulating valve 10, as shown in FIG. 5, so that each set of jetting means may differ from others in terms of an amount or pressure of jetted air.", "It is further possible to make an air jetting position of a nozzle of each set of jetting means to be different from others by 60°, for example.", "It is also possible to make the direction of air jetted from an orifice of each nozzle 3 to be inclined downward by an inclination angle up to 30°, for example, as shown in FIG. 9. Each nozzle 3 is arranged so that it may be supplied with high-pressure air from an unillustrated compressor.", "Air jetted from nozzle 3 in this case, after hitting the outer surface of drum base body 1, does not go upward but does go downward without fail so as not to adversely affect the layer of light-sensitive solution coated by coating head 2, thereby preventing any coating defect.", "As long as the direction of jetting from nozzle 3 is inclined, air, after hitting, never goes up.", "It is also possible to have an arrangement wherein a continuous slit 3 is provided on a ring-shaped blowing, means so that the continuous slit may face drum base body 1 and so that the direction of jetting from the slit is inclined downward.", "FIG. 6, for example, shows a case where the fluid outlet is a ring-shaped slit, located underneath the coater.", "Further, although each nozzle 3 is positioned horizontally, it is also possible to have an arrangement wherein each direction of air jetting has a deviation without pointing to the center of drum base body 1 and is inclined by a certain angle from the radial direction from the center of the drum base body, for example, as shown in FIG. 8. In this case, air jetted from nozzle 3, after it hits drum base body 1, goes mostly horizontally and never goes up.", "FIG. 3 shows the second example wherein four air-ejecting nozzles 3 are provided around drum base body 1 with an angular interval of 90°.", "The number of nozzles 3 is not limited as shown in this example.", "FIG. 4 shows a case where the outlet nozzle 3 is shaped along the curve of the drum surface.", "As a photosensitive liquid, it is possible to use inorganic photosensitive materials such as zinc oxide and cadmium sulfide as well as organic photosensitive materials such as polyvinylcarbazole and trinitrofluorene both dispersed in a high molecular binder.", "In addition, it is also possible to use a photosensitive layer of a function-separated type wherein a charge generating layer and a charge transport layer are laminated, so as to meet the recent demand for high sensitivity and improved durability.", "For example, a charge generating layer is obtained by dispersing azo pigment, quinone pigment perylene pigment, phthalocyanine pigment or anthanthrone pigment in a high molecular binder such as polycarbonate, and a charge transport layer is obtained by dispersing polycyclic aromatic compound or a nitrogen-containing cyclic compound in a high molecular binder.", "The thickness of a charge generating layer is 0.01-10 μm and preferably is 0.05-5 μm, while that of a charge transport layer is preferably 5-30 μm.", "The range of viscosity of photosensitive liquid is 0.5-700 cp and it is preferably 1-500 cp.", "Further, as a hollow drum for electrophotography use, aluminum, stainless steel or plastic on which a conductive layer is formed can be used.", "In addition to that, it is also possible to use a hollow drum wherein a subbing layer and a charge generating layer are formed in advance.", "As stated above, the invention has an advantage in that a drum can be positioned accurately without being touched and thereby without being scratched.", "The invention has a further advantage in that dust particles sticking to the drum are removed by sprayed air, thereby improving the coating efficiency." ]
BACKGROUND OF THE INVENTION This invention concerns a system to protect active or passive electronic equipment from radar detection, in other words equipment which transmits or receives microwave radiation, for example a radar or telecommunications transmitter or receiver. Equipment such as those equipped with antennas, strongly reflect microwaves and, consequently, are easily detected by radar. There exist different devices which absorb to a certain degree an incident microwave, or which, more generally, mask the potential target from a radar beam. However, such devices, often with a very limited efficiency, cannot generally be used to protect electronic equipment, as they perturb both transmission and reception. SUMMARY OF THE INVENTION This invention relates to a system to ensure the protection of electronic equipment without causing functional perturbation. For this purpose, the transmitting and/or receiving surface is covered with a device which can be commanded to induce a given phase shift, for example, approximately π/2, which enables a microwave incident on the equipment to be modulated in phase; the wave reflected by the equipment has its frequency spectrum modified and spread, making it more difficult for the radar to detect the equipment. In order not to cause functional perturbation in the protected equipment, an inverse modulation is applied to the signal transmitted and/or received. BRIEF DESCRIPTION OF THE DRAWINGS Other purposes, characteristics and results of the present invention will appear on reading the following description, with reference to the drawings in which: FIG. 1 represents a block diagram of the device according to the invention; FIGS. 2a, 2b, and 2c represent timing diagrams of a first operating mode of the device, according to the invention; FIGS. 3a, 3b, and 3c represent timing diagrams of a second operating mode of the device, according to the invention; FIGS. 4 and 5 represent an embodiment of the phase shifting means used in the device according to the invention. The same reference numbers are used in all these figures to refer to the same elements. DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a block diagram of the device according to the invention. This figure illustrates the equipment E requiring protection, for example comprising a transmitter/receiver assembly TR, connected to an antenna A used to transmit and receive microwave electromagnetic radiation commanded by the TR assembly. The equipment E may be a radar, for example. According to the invention, the transmitting and/or receiving surface of the equipment E, in all cases at least the antenna A surface, is covered with the means M E forming a phase modulator and enabling, on commands from the control system C, a shift of approximately π/2 to be communicated to an incident microwave signal 11. The incident wave 11 may originate from an external radar, trying to detect the appliance carrying equipment E. As is known, part of this wave 11 is reflected by antenna A; it crosses back through the modulator M E and undergoes a further shift of π/2 and forms the reflected wave 12; the wave 12 has now been shifted in relation to the incident wave 11. In this way, when controlling the modulator M E a modulation of phase 0-π can be communicated to an external radar wave. Furthermore, this phase shift can be applied at any frequency f and, generally speaking, according to any variation law which in practice is only limited by the switching time of the modulator M E . It should be noted for complete information, that the modulating frequency f of the modulator M E must remain sufficiently low to allow the wave 11 to see the same modulator M E phase state on the outward and return path (after reflection), which in practice is not a constraint. For example, the frequency f may be in a range of several megahertz. Moreover, as the microwave energy transmitted or received by the equipment E has itself been phase modulated by the device M E , the invention provides for a second phase modulator M I , commanded in synchronization with the modulator M E by the means C. The modulator M I serves to compensate the modulation caused by the device M E , in other words to apply to the signal transmitted or received by the assembly TR a phase modulation identical but opposite to that of the phase modulation applied by the modulator M E to the microwave transmitted or received by antenna A. The modulator M I can be constructed in any known manner. For example, phase modulation can be generated at the output of a local oscillator, generally to be found in this type of equipment, whose signal is mixed with the signal transmitted or received by the equipment. In a variant of this embodiment, illustrated by the dotted line 10 in FIG. 1, the phase modulator M E can surround the complete assembly E requiring protection. The FIGS. 2a and 2b are timing diagrams representing a first operating mode of the device according to the invention. FIG. 2a represents an example of the type of signal likely to be supplied by the assembly TR in FIG. 1 when a signal is transmitted by antenna A. It may consist of a series of pulses, marked 21, 22 and 23 at equal distances in time, modulating a microwave signal, not represented for reasons of clarity. FIG. 2b represents the modulation law applied to a wave crossing the modulator M E , whether it is a wave to be received by the antenna A or transmitted by the antenna A or the reflection of an incident wave on the antenna A. We see that the phase modulation varies periodically between 0 and π/2, for example sinusoiidally with a frequency f. This modulation is applied continuously except during the instants which corresponds to the transmission of pulses 21, 22 and 23. FIG. 2c represents the modulation applied by the phase modulator M I to the signal transmitted by the antenna A towards the assembly TR or vice versa. In this case the modulation is periodic with the same frequency f between O and π/2 but is the inverse of the preceding modulation, in other words with a phase difference of π; this modulation, as in the case of the modulator M E , is continuous except during the transmission period of pulses 21, 22 and 23. The system operates in the following way: When the equipment E transmits a pulse (21-23), this crosses the modulator M E without the latter applying any modulation. The microwave incident on the equipment between pulses 21-23, for example echoes of pulses transmitted by itself, undergoes a phase modulation of 0-π/2 applied by the modulator M E as shown in FIG. 2b. This modulation is compensated by the inverse modulation applied by the modulator M I to the signal destined for the assembly TR, as shown in FIG. 2c. In this way, the signal received by the equipment E in the form of an echo of its transmissions is not perturbed either on transmission or reception. As regards the microwaves which do not concern the operation of the equipment E, the modulator M E applies to them, outside the periods of transmission of pulses 21 . . . 23, a phase modulation of 0-π/2; the part of this incident energy which is reflected by the antenna A crosses back through the modulator M E and undergoes a second phase shift, after which the wave 12 reflected by the system has a phase modulation of 0-π. This type of modulation has various effects on the external radar having transmitted a wave such as 11-12: first, it spreads the spectrum of the reflected wave in relation to that of the incident wave; the external radar having transmitted the wave at a frequency F O can only operate in a relatively narrow band around this frequency; the energy it receives in this band is found to be significantly lower than the energy that would have been received without modulation. Furthermore, if the modulation frequency (f) is sufficiently high, the maxima induced by the phase modulation would be outside the radar band limits; in this case, the echoed signal received by the radar operating at frequency F O becomes so weak that it appears as noise and cannot be detected. In addition, this modulation at frequency f which is unknown to the radar having transmitted the wave at frequency F O , completely changes the echo characteristic of the equipment E and its vehicle, which reduces further the possibility of the latter being detected by radar - even if the radar power is increased to compensate for these protective measures. The above description is given for a periodic variation at frequency f (sinusoidal, for example) of the diode control current. Other types of variation may of course be used, such as the control of diodes using random variations which result in an even more pronounced decharacterization of the radar echo. FIGS. 3a, 3b and 3c are timing diagrams analogous to those in FIGS. 2a, 2b and 2c, representing a second operating mode of the device according to the invention. FIG. 3a is identical to the FIG. 2a and represents the transmitting periods of the equipment E. FIG. 3b represents the phase modulation applied to a microwave by modulator M E . As in the previous case, and by way of example, the modulation is periodic, for example sinusoidal, and varies from 0 to π/2 at frequency f. However, unlike the previous case, this modulation is continuous, in other words, modulation is effective even during the transmission periods 21 to 23. FIG. 3c represents the modulation of modulator M I . As previously, this modulation is the opposite of that of modulator M E , in this case the modulation is periodic varying from 0 to π/2 at frequency f and is continuous. The system operates in the following way: As regards transmissions (21-23) from equipment E, the signal generated by the assembly TR is pre-modulated by the modulator M I , whose modulation is compensated by the inverse modulation applied by the modulator M E to the wave transmitted by the antenna A. During reception of signals originating in the equipment E by this equipment, the system operates in the same way as that described in FIGS. 2a-2c the wave is modulated before being received by the antenna A (modulator M E ), and this is compensated after the antenna by the modulator M I . Therefore, as previously, the signal from the equipment E suffers no perturbation either on reception or on transmission. During reception of signals not originating in the equipment E, the system functions in the same way as in FIGS. 2a-2c, to the extent that it remains operative continuously. FIG. 4 represents an embodiment of the phase modulator M E used in the device according to the invention. French patents 69.35239 and 77.19365 describe the dielectric panels equipped with switchable elements (diodes) to allow controlled phase shifting of a microwave signal. The modulator in FIG. 4 belongs to this family of devices. It consists of three panels P 1 , P 2 and P 3 , mounted substantially parallel to each other on an axis XX which for example corresponds to the axis of the antenna A (FIG. 1). These panels are at a distance d from each other. FIG. 5 is a partial view of a practical embodiment of one of the panels P 1 . . . P 3 . This panel is made of a electrically insulating substrate 20, equipped with a plurality of semiconducting elements; in this embodiment, the substrate has two diode networks. The first network consists of diodes, marked D 1 , all connected in the same direction in order to form a series of parallel lines. The second network consists of diodes D 2 , all connected in the same direction to form columns substantially perpendicular to the previous lines. Conducting chips 21, disk-shaped for example, are located at the intersections of the lines and columns. Line spacing can be substantially equal to column spacing of a value of approximately λ/2, where λ is the average wavelength of the modulator operating bandwidth; spacing of diodes D 1 and D 2 is constant within the lines or columns and can advantageously be the same for the lines and columns, thus forming a square grid. For reasons of clarity, the disks 21' are shown hatched, although they are not in fact viewed in section. Conductors (not shown), placed on the edge of the panel to interconnect the disks 21 provide the polarization of diodes D 1 and D 2 . The function of the disks 21' is to provide impedance matching for the panel. It is to be noted that they are represented as circular disks with notches for diode connection but they can be shaped differently (ring, cross, surfaced with cut-outs, etc . . . ), the actual shape being defined experimentally to improve the impedance matching of the panel. In this embodiment conducting patches 22' have been placed between the disks 21' to complete matching. In a variant of this embodiment the two diode networks are placed one on each side of the substrate 20, in which case the diodes D 1 are no longer connected to diodes D 2 but controlled synchronously. This embodiment simplifies the diode supply problem. This three-panel assembly operates depending on whether or not the incident wave is in its working frequency band, which must be substantially that of the equipment E. Within this band, the modulator is readily matched and therefore imposes no reflection on the incident wave, especially on waves going to or coming from the equipment E. The modulator in this case presents two operating modes, depending on the state of the diodes, between which there is a shift close to 90°: in a first state, the three-panel assembly diodes are conducting, in other words polarized directly by a large current (near saturation); in the second state, the diodes are not conducting, but blocked by a reverse bias. The geometric and electric characteristics of the panels (line and column spacing, diode spacing, shapes and dimensions of chips and patches, electrical characteristics of diodes, etc) are defined so that, at the average wavelength in the operating band: in one of the diode states (blocked for example), if the panel P 1 has a susceptance B, the panel P 3 has the same susceptance B and the panel P 2 , twice the susceptance (2B); in the other diode state (conducting state) the susceptance of all the panels is zero. The susceptance value B is defined by the value φ o of the differential phase shift required between the two above-mentioned states, based on the following equation: B=2 tan (φ.sub.o.1/(n+1)) where n is the number of panels. The distance (d) between panels is given by the following expression: d=(λ/2π). Arctan (2/B) However, through calculation and experimentation it has been shown that the operation of the device remains satisfactory for a wide range of values around the value given above: for example, a factor of 2 applied to the distance d calculated above remains acceptable. By using at least three substantially equidistant panels P 1 , P 2 , P 3 with respective susceptances B, 2B and B, it is possible to obtain a matched device with two states, between which there is a differential phase shift φ o , for which a choice of value also determines that of B and, moreover, the configuration of each panel. For example, the value of φ o is equal to 90° when the value of B is close to 0.8. In a variant of the embodiment, the three panels P 1 , P 2 , P 3 can be moulded into a dielectric material such as foam, acting notably as a mechanical support. In this case, the distance expression d is to be corrected by the factor ε 1/2 , where ε is the dielectric constant of the material. The modulator M E can include more than three panels provided that the following panel susceptance sequence is respected: a first and last panel each with susceptance B, separated by n-2 panels with susceptance 2B; by multiplying the number of panels the modulator bandwidth is enlarged. It should be noted that the matching described above occurs strictly only when the wave is transmitted parallel to the XX axis. However, the distance and susceptance vary with incidence and the effects of these variations tend to compensate each other in such a way that the modulator's behavior remains satisfactory; by way of example, using the previous values, a standing wave rate less than 1.4 can be obtained for an incident wave within a 120° cone angle. Outside the modulator bandwidth the modulator becomes reflective during one of its state (the conducting state for low frequencies or the blocked state for high frequencies) and remains matched for its other state. The result is that an incident microwave is reflected, depending on the modulator state, either by the first modulator panel, or (partially) by the antenna of the equipment with a differential phase shift between these two situations mainly due to the difference the wave has covered in the two cases. Therefore, the result in this case is also a phase modulation corresponding to the frequency of switching between the two modulator states. The experimental phase-shift values obtained were no longer in the 180° range but are still about 120°. The above description is given as a non-limitative example. For example, the differential phase shift imposed by the modulator M E does not have to be π/2 but may have a lower value. Experimentally, it has been observed that the effect on attenuation and decharacterization of the radar echo of the equipment for an external radar beam can be considered satisfactory for phase shifts φ o in the 50° range. It is on this basis that the description contains one modulator M E placed in front of the equipment E, but it is equally possible to place several independently-controlled M E -type modulators alongside the first one; by applying either the same modulation law, phase-shifted in relation to time, or different laws, to the various modulators, a deflection or, more generally, a spatial dispersion of the reflected wave is thus obtained.
This invention concerns a system to protect active or passive electronic equipment from radar detection. In other words equipment which transmits or receives microwave radiation, for example a radar or telecommunications transmitter or receiver. For this purpose, the transmitting surface of the equipment is covered by a device which can be controlled to apply a phase shift of approximately π/2 to the incident wave; this enables a microwave incident on the equipment to be modulated in phase. The frequency spectrum of the wave reflected by the equipment is modified and spread thus making it more difficult to detect the equipment. To avoid any perturbation of the operation of the equipment, an inverse modulation is applied to signals transmitted and/or received by the equipment itself.
Summarize the information, clearly outlining the challenges and proposed solutions.
[ "BACKGROUND OF THE INVENTION This invention concerns a system to protect active or passive electronic equipment from radar detection, in other words equipment which transmits or receives microwave radiation, for example a radar or telecommunications transmitter or receiver.", "Equipment such as those equipped with antennas, strongly reflect microwaves and, consequently, are easily detected by radar.", "There exist different devices which absorb to a certain degree an incident microwave, or which, more generally, mask the potential target from a radar beam.", "However, such devices, often with a very limited efficiency, cannot generally be used to protect electronic equipment, as they perturb both transmission and reception.", "SUMMARY OF THE INVENTION This invention relates to a system to ensure the protection of electronic equipment without causing functional perturbation.", "For this purpose, the transmitting and/or receiving surface is covered with a device which can be commanded to induce a given phase shift, for example, approximately π/2, which enables a microwave incident on the equipment to be modulated in phase;", "the wave reflected by the equipment has its frequency spectrum modified and spread, making it more difficult for the radar to detect the equipment.", "In order not to cause functional perturbation in the protected equipment, an inverse modulation is applied to the signal transmitted and/or received.", "BRIEF DESCRIPTION OF THE DRAWINGS Other purposes, characteristics and results of the present invention will appear on reading the following description, with reference to the drawings in which: FIG. 1 represents a block diagram of the device according to the invention;", "FIGS. 2a, 2b, and 2c represent timing diagrams of a first operating mode of the device, according to the invention;", "FIGS. 3a, 3b, and 3c represent timing diagrams of a second operating mode of the device, according to the invention;", "FIGS. 4 and 5 represent an embodiment of the phase shifting means used in the device according to the invention.", "The same reference numbers are used in all these figures to refer to the same elements.", "DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a block diagram of the device according to the invention.", "This figure illustrates the equipment E requiring protection, for example comprising a transmitter/receiver assembly TR, connected to an antenna A used to transmit and receive microwave electromagnetic radiation commanded by the TR assembly.", "The equipment E may be a radar, for example.", "According to the invention, the transmitting and/or receiving surface of the equipment E, in all cases at least the antenna A surface, is covered with the means M E forming a phase modulator and enabling, on commands from the control system C, a shift of approximately π/2 to be communicated to an incident microwave signal 11.", "The incident wave 11 may originate from an external radar, trying to detect the appliance carrying equipment E. As is known, part of this wave 11 is reflected by antenna A;", "it crosses back through the modulator M E and undergoes a further shift of π/2 and forms the reflected wave 12;", "the wave 12 has now been shifted in relation to the incident wave 11.", "In this way, when controlling the modulator M E a modulation of phase 0-π can be communicated to an external radar wave.", "Furthermore, this phase shift can be applied at any frequency f and, generally speaking, according to any variation law which in practice is only limited by the switching time of the modulator M E .", "It should be noted for complete information, that the modulating frequency f of the modulator M E must remain sufficiently low to allow the wave 11 to see the same modulator M E phase state on the outward and return path (after reflection), which in practice is not a constraint.", "For example, the frequency f may be in a range of several megahertz.", "Moreover, as the microwave energy transmitted or received by the equipment E has itself been phase modulated by the device M E , the invention provides for a second phase modulator M I , commanded in synchronization with the modulator M E by the means C. The modulator M I serves to compensate the modulation caused by the device M E , in other words to apply to the signal transmitted or received by the assembly TR a phase modulation identical but opposite to that of the phase modulation applied by the modulator M E to the microwave transmitted or received by antenna A. The modulator M I can be constructed in any known manner.", "For example, phase modulation can be generated at the output of a local oscillator, generally to be found in this type of equipment, whose signal is mixed with the signal transmitted or received by the equipment.", "In a variant of this embodiment, illustrated by the dotted line 10 in FIG. 1, the phase modulator M E can surround the complete assembly E requiring protection.", "The FIGS. 2a and 2b are timing diagrams representing a first operating mode of the device according to the invention.", "FIG. 2a represents an example of the type of signal likely to be supplied by the assembly TR in FIG. 1 when a signal is transmitted by antenna A. It may consist of a series of pulses, marked 21, 22 and 23 at equal distances in time, modulating a microwave signal, not represented for reasons of clarity.", "FIG. 2b represents the modulation law applied to a wave crossing the modulator M E , whether it is a wave to be received by the antenna A or transmitted by the antenna A or the reflection of an incident wave on the antenna A. We see that the phase modulation varies periodically between 0 and π/2, for example sinusoiidally with a frequency f. This modulation is applied continuously except during the instants which corresponds to the transmission of pulses 21, 22 and 23.", "FIG. 2c represents the modulation applied by the phase modulator M I to the signal transmitted by the antenna A towards the assembly TR or vice versa.", "In this case the modulation is periodic with the same frequency f between O and π/2 but is the inverse of the preceding modulation, in other words with a phase difference of π;", "this modulation, as in the case of the modulator M E , is continuous except during the transmission period of pulses 21, 22 and 23.", "The system operates in the following way: When the equipment E transmits a pulse (21-23), this crosses the modulator M E without the latter applying any modulation.", "The microwave incident on the equipment between pulses 21-23, for example echoes of pulses transmitted by itself, undergoes a phase modulation of 0-π/2 applied by the modulator M E as shown in FIG. 2b.", "This modulation is compensated by the inverse modulation applied by the modulator M I to the signal destined for the assembly TR, as shown in FIG. 2c.", "In this way, the signal received by the equipment E in the form of an echo of its transmissions is not perturbed either on transmission or reception.", "As regards the microwaves which do not concern the operation of the equipment E, the modulator M E applies to them, outside the periods of transmission of pulses 21 .", "23, a phase modulation of 0-π/2;", "the part of this incident energy which is reflected by the antenna A crosses back through the modulator M E and undergoes a second phase shift, after which the wave 12 reflected by the system has a phase modulation of 0-π.", "This type of modulation has various effects on the external radar having transmitted a wave such as 11-12: first, it spreads the spectrum of the reflected wave in relation to that of the incident wave;", "the external radar having transmitted the wave at a frequency F O can only operate in a relatively narrow band around this frequency;", "the energy it receives in this band is found to be significantly lower than the energy that would have been received without modulation.", "Furthermore, if the modulation frequency (f) is sufficiently high, the maxima induced by the phase modulation would be outside the radar band limits;", "in this case, the echoed signal received by the radar operating at frequency F O becomes so weak that it appears as noise and cannot be detected.", "In addition, this modulation at frequency f which is unknown to the radar having transmitted the wave at frequency F O , completely changes the echo characteristic of the equipment E and its vehicle, which reduces further the possibility of the latter being detected by radar - even if the radar power is increased to compensate for these protective measures.", "The above description is given for a periodic variation at frequency f (sinusoidal, for example) of the diode control current.", "Other types of variation may of course be used, such as the control of diodes using random variations which result in an even more pronounced decharacterization of the radar echo.", "FIGS. 3a, 3b and 3c are timing diagrams analogous to those in FIGS. 2a, 2b and 2c, representing a second operating mode of the device according to the invention.", "FIG. 3a is identical to the FIG. 2a and represents the transmitting periods of the equipment E. FIG. 3b represents the phase modulation applied to a microwave by modulator M E .", "As in the previous case, and by way of example, the modulation is periodic, for example sinusoidal, and varies from 0 to π/2 at frequency f. However, unlike the previous case, this modulation is continuous, in other words, modulation is effective even during the transmission periods 21 to 23.", "FIG. 3c represents the modulation of modulator M I .", "As previously, this modulation is the opposite of that of modulator M E , in this case the modulation is periodic varying from 0 to π/2 at frequency f and is continuous.", "The system operates in the following way: As regards transmissions (21-23) from equipment E, the signal generated by the assembly TR is pre-modulated by the modulator M I , whose modulation is compensated by the inverse modulation applied by the modulator M E to the wave transmitted by the antenna A. During reception of signals originating in the equipment E by this equipment, the system operates in the same way as that described in FIGS. 2a-2c the wave is modulated before being received by the antenna A (modulator M E ), and this is compensated after the antenna by the modulator M I .", "Therefore, as previously, the signal from the equipment E suffers no perturbation either on reception or on transmission.", "During reception of signals not originating in the equipment E, the system functions in the same way as in FIGS. 2a-2c, to the extent that it remains operative continuously.", "FIG. 4 represents an embodiment of the phase modulator M E used in the device according to the invention.", "French patents 69.35239 and 77.19365 describe the dielectric panels equipped with switchable elements (diodes) to allow controlled phase shifting of a microwave signal.", "The modulator in FIG. 4 belongs to this family of devices.", "It consists of three panels P 1 , P 2 and P 3 , mounted substantially parallel to each other on an axis XX which for example corresponds to the axis of the antenna A (FIG.", "1).", "These panels are at a distance d from each other.", "FIG. 5 is a partial view of a practical embodiment of one of the panels P 1 .", "P 3 .", "This panel is made of a electrically insulating substrate 20, equipped with a plurality of semiconducting elements;", "in this embodiment, the substrate has two diode networks.", "The first network consists of diodes, marked D 1 , all connected in the same direction in order to form a series of parallel lines.", "The second network consists of diodes D 2 , all connected in the same direction to form columns substantially perpendicular to the previous lines.", "Conducting chips 21, disk-shaped for example, are located at the intersections of the lines and columns.", "Line spacing can be substantially equal to column spacing of a value of approximately λ/2, where λ is the average wavelength of the modulator operating bandwidth;", "spacing of diodes D 1 and D 2 is constant within the lines or columns and can advantageously be the same for the lines and columns, thus forming a square grid.", "For reasons of clarity, the disks 21'", "are shown hatched, although they are not in fact viewed in section.", "Conductors (not shown), placed on the edge of the panel to interconnect the disks 21 provide the polarization of diodes D 1 and D 2 .", "The function of the disks 21'", "is to provide impedance matching for the panel.", "It is to be noted that they are represented as circular disks with notches for diode connection but they can be shaped differently (ring, cross, surfaced with cut-outs, etc .", "), the actual shape being defined experimentally to improve the impedance matching of the panel.", "In this embodiment conducting patches 22'", "have been placed between the disks 21'", "to complete matching.", "In a variant of this embodiment the two diode networks are placed one on each side of the substrate 20, in which case the diodes D 1 are no longer connected to diodes D 2 but controlled synchronously.", "This embodiment simplifies the diode supply problem.", "This three-panel assembly operates depending on whether or not the incident wave is in its working frequency band, which must be substantially that of the equipment E. Within this band, the modulator is readily matched and therefore imposes no reflection on the incident wave, especially on waves going to or coming from the equipment E. The modulator in this case presents two operating modes, depending on the state of the diodes, between which there is a shift close to 90°: in a first state, the three-panel assembly diodes are conducting, in other words polarized directly by a large current (near saturation);", "in the second state, the diodes are not conducting, but blocked by a reverse bias.", "The geometric and electric characteristics of the panels (line and column spacing, diode spacing, shapes and dimensions of chips and patches, electrical characteristics of diodes, etc) are defined so that, at the average wavelength in the operating band: in one of the diode states (blocked for example), if the panel P 1 has a susceptance B, the panel P 3 has the same susceptance B and the panel P 2 , twice the susceptance (2B);", "in the other diode state (conducting state) the susceptance of all the panels is zero.", "The susceptance value B is defined by the value φ o of the differential phase shift required between the two above-mentioned states, based on the following equation: B=2 tan (φ.", "sub.", "o[.", "].1/(n+1)) where n is the number of panels.", "The distance (d) between panels is given by the following expression: d=(λ/2π).", "Arctan (2/B) However, through calculation and experimentation it has been shown that the operation of the device remains satisfactory for a wide range of values around the value given above: for example, a factor of 2 applied to the distance d calculated above remains acceptable.", "By using at least three substantially equidistant panels P 1 , P 2 , P 3 with respective susceptances B, 2B and B, it is possible to obtain a matched device with two states, between which there is a differential phase shift φ o , for which a choice of value also determines that of B and, moreover, the configuration of each panel.", "For example, the value of φ o is equal to 90° when the value of B is close to 0.8.", "In a variant of the embodiment, the three panels P 1 , P 2 , P 3 can be moulded into a dielectric material such as foam, acting notably as a mechanical support.", "In this case, the distance expression d is to be corrected by the factor ε 1/2 , where ε is the dielectric constant of the material.", "The modulator M E can include more than three panels provided that the following panel susceptance sequence is respected: a first and last panel each with susceptance B, separated by n-2 panels with susceptance 2B;", "by multiplying the number of panels the modulator bandwidth is enlarged.", "It should be noted that the matching described above occurs strictly only when the wave is transmitted parallel to the XX axis.", "However, the distance and susceptance vary with incidence and the effects of these variations tend to compensate each other in such a way that the modulator's behavior remains satisfactory;", "by way of example, using the previous values, a standing wave rate less than 1.4 can be obtained for an incident wave within a 120° cone angle.", "Outside the modulator bandwidth the modulator becomes reflective during one of its state (the conducting state for low frequencies or the blocked state for high frequencies) and remains matched for its other state.", "The result is that an incident microwave is reflected, depending on the modulator state, either by the first modulator panel, or (partially) by the antenna of the equipment with a differential phase shift between these two situations mainly due to the difference the wave has covered in the two cases.", "Therefore, the result in this case is also a phase modulation corresponding to the frequency of switching between the two modulator states.", "The experimental phase-shift values obtained were no longer in the 180° range but are still about 120°.", "The above description is given as a non-limitative example.", "For example, the differential phase shift imposed by the modulator M E does not have to be π/2 but may have a lower value.", "Experimentally, it has been observed that the effect on attenuation and decharacterization of the radar echo of the equipment for an external radar beam can be considered satisfactory for phase shifts φ o in the 50° range.", "It is on this basis that the description contains one modulator M E placed in front of the equipment E, but it is equally possible to place several independently-controlled M E -type modulators alongside the first one;", "by applying either the same modulation law, phase-shifted in relation to time, or different laws, to the various modulators, a deflection or, more generally, a spatial dispersion of the reflected wave is thus obtained." ]
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of earlier filed U.S. provisional patent application No. 60/672,624, filed Apr. 19, 2005, and having the same title and inventor as above. FIELD OF THE INVENTION [0002] The present invention relates to snowboards and like devices and more specifically to a compactable or retractable mechanism for bearing weight from the board during a chair lift ride. BACKGROUND OF THE INVENTION [0003] Snowboarding is a relatively new and growing winter recreational activity. The experience is somewhat similar to a skateboarding experience, though, among other differences, in snowboarding a user's feet are fixedly attached to a board during use. After a run, a user releases one foot, normally the rear foot, and pushes with that foot to maneuver through chair lift lines and onto a chair lift. During the chair lift ride, the board dangles unbalanced and uncomfortably from the permanently attached foot. Upon exiting the chair lift, a user reattaches his or her free “foot” before descending a run. [0004] A need exists to alleviate the awkward and uncomfortable situation of having a board dangle from a user's foot during a chair lift ride. Several prior art devices are known that address this problem. They include the devices disclosed in U.S. Pat. No.: 6,349,968 issued to Owen; U.S. Pat. No. 5,951,048 issued to Slaughter; U.S. Pat. No. 5,564,729 issued to Gomez; U.S. Pat. No. 5,090,722 issued to Ritchie; U.S. Pat. No. 5,356,159 issued to Butterfield; and U.S. Pat. No. 6,247,728 issued to Verville. [0005] U.S. Pat. No. 6,349,968 to Owen teaches a cord with a releasable carbiner type clamp. This device is disadvantageous for several reasons including that if there is any problem with release, due to operator error or mechanical failure, the user is unreleasably coupled to the moving chair lift, potentially resulting in serious injury at unloading and/or stoppage of the lift apparatus. Also the extended cord does not lend itself to ready and secure stowage. [0006] Various other know devices, such as those disclosed in U.S. Pat. No.: 5,090,722 to Ritchie, U.S. Pat. No. 5,356,159 to Butterfield and U.S. Pat. No. 6,247,728 to Verville, illustrate positive engagement devices provided on boards, bindings or boots where the “free” foot is temporarily coupled to the board through the positive engagement device. These devices tend to be disadvantageous in that they may be difficult to use particularly in winter conditions where parts may frequently be clogged with snow or ice and cold fingers may loose the dexterity required for operation. Also, device reliability is questionable due in part to fouling or inherent design limitations in the devices or the object to which they attach, etc. Furthermore, while they may balance weight more evenly over two feet, the weight of the board and boots, etc., is wholly supported by the legs not permitting leg muscles to rest more fully before the next run. [0007] A need thus exists for a mechanism for better supporting a snowboard or like device during chair lift or related transport. This need may include the need for a device that more evenly balances weight, can mount to a lift chair or other structure in a supportive, secure manner which is readily and inherently separable from the chair or structure, is readily and securely stowable when not in use and/or directly supports board weight permitting legs to rest, among other needs. [0008] Accordingly, it is an object of the present invention to provide these and related features or functionality. The attainment of these and related features and advantages should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention taken together with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0009] FIG. 1 is a perspective view of one embodiment of a snowboard support device in accordance with the present invention is shown. [0010] FIG. 2 illustrates the device of FIG. 1 in a stowage position, while FIG. 3 illustrates the device in an extended position. [0011] FIGS. 4 and 5 perspective views the device of FIG. 1 at different levels of extension, while FIG. 6 is side elevation view of the device in the extended position. [0012] FIGS. 7-8 are exploded perspective views of the device of FIG. 1 and the top extension shaft of that device, respectively. [0013] FIGS. 9-10 are a top plan view and a side elevation view illustrating cam-based positioning of the handle and shaft, respectively, of the device of FIG. 1 . DETAILED DESCRIPTION [0014] Referring to FIG. 1 , a perspective view of a snowboard support device 50 in accordance with the present invention is shown. FIG. 1 illustrates device 50 in an extended position with handle/housing (“handle”) 23 resting on a chair lift seat 60 . Device 50 is preferably mounted to a snowboard 70 or other device through an extension 71 of binding plate 1 (shown in other figures) or other suitable means. Extension shaft 52 may be pivotally coupled to base 4 through a shuttle 6 movably mounted on shuttle shaft 5 . Extension shaft 52 may have a telescoping configuration and include a lower, middle and upper section 9 , 14 , 22 , respectively. Handle 23 may be pivotally coupled to upper section 22 and configured to not extend substantially past 90 degrees. [0015] FIG. 2 illustrates device 50 in a stowage position compactly contracted within handle 23 . FIG. 3 illustrates device 50 in an extended position. The base 4 , shuttle 6 and extension shaft 52 are visible in this view. The binding plate 1 and disk 2 , pivot arm 13 , release latch 24 and other features are also shown. [0016] Device 50 is preferably biased towards the extended position. To contract it, a user applies a downward force in the direction of arrow C to compress the shaft and then in the direction of arrow B to move the orientation of shaft 52 toward horizontal. Movement in the direction of arrow B causes the lower section of shaft 52 to pivot about pivot arm 13 and move via movement of shuttle 6 on shuttle shaft 5 (see FIG. 4 ) in the direction of arrow D. Handle 23 is moved generally downward in the direction of arrow A until it mounts on and “clicks” into base 4 . To extend the device, latch release mechanism 24 is actuated by a user which releases handle 23 from base 4 and permits a user to extend the handle to the extended position for resting on a chair lift seat as shown in FIG. 1 (and the handle is preferably biased towards this extended position). It should be recognized that by merely resting on the chair lift seat (as opposed to positively attaching such as with a clip or carbiner), the present invention is much less likely to become inadvertently attached to the chair lift. [0017] FIGS. 4-6 are three perspective views illustrating embodiments of device 50 at three different levels of extension. FIGS. 7-8 are two exploded perspective views that illustrate the various components of the embodiments of device 50 of FIGS. 4-6 . [0018] The mounting of a binding plate 1 to a board is known. For device 50 , an exterior region 71 is provided with binding plate 1 and clips 3 are used to mount base 4 to the binding plate. Shaft 5 is provided within the structure of base 4 and shuttle 6 is preferably configured for movement along shaft 5 . Spring 20 biases housing 6 away from a contracted position causing shaft 52 to rise up in response to a release of latch mechanism 24 (described below). Axle 7 facilitates pivotal coupling of shaft 52 to shuttle 6 . [0019] Pivot arm 13 is coupled to a pivot member 11 into which shuttle shaft 5 is inserted. These items are held in place by firmly secured base 4 . Pivot arm 13 is coupled to lower shaft section 9 . [0020] Extension shaft sections 9 , 14 , 22 telescope within each other. See, for example, FIG. 6 . A spring tempered anchor 36 is preferably provided in top section 22 to absorb shocks and some lateral movement. [0021] FIG. 8 illustrates details of the handle 23 and top shaft section 22 . Latch actuator 24 is movably coupled through pin 25 to handle 23 and further to internal latch 29 . Cam spring 28 biased latch 29 towards engagement. When handle 23 is pressed onto base 4 the teeth 30 of latch 29 hook underneath ledge 38 of base 4 (see FIG. 7 ). To release the handle from the base, latch actuator 24 is pushed forward causing the internal latch 29 to rotate such that teeth 30 disengage ledge 38 . Lock knob 27 in the straight up position blocks movement of latch 24 . [0022] Anchor 36 may include an axial screw 35 that mounts cam 32 and spring 33 to top shaft section 22 adjacent pin 31 . The spring and cam serve to center top shaft section 22 and provide some flexibility and shock absorption. [0023] FIGS. 9 and 10 illustrate features of the functionality of device 50 . The bottom two shaft sections are preferably configured such that they do not turn (though they may be configured otherwise without departing from the invention). The top shaft section 22 is preferably coupled through a cam arrangement that permits turning, but recenters in the absence of a turning force as discussed above with reference to FIG. 8 , and shown in FIG. 9 . FIG. 10 illustrates that the extension shaft may be provided with shuttle 6 and cam spring 20 ( FIG. 7 ) such that the shuttle is biased towards vertical with a certain amount of play. [0024] Components may be made of metal, plastic or other suitable materials. [0025] While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention and the limits of the appended claims.
A snowboard support device for use in lift assist transport. The device may have a base, an extension shaft and a handle member or the like. In one embodiment, the handle serves as a housing to cover the extension shaft in its closed position and provides an engagement surface for non-fixed, gravity-based engagement of a chair lift seat.
Identify the most important claim in the given context and summarize it
[ "CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of earlier filed U.S. provisional patent application No. 60/672,624, filed Apr. 19, 2005, and having the same title and inventor as above.", "FIELD OF THE INVENTION [0002] The present invention relates to snowboards and like devices and more specifically to a compactable or retractable mechanism for bearing weight from the board during a chair lift ride.", "BACKGROUND OF THE INVENTION [0003] Snowboarding is a relatively new and growing winter recreational activity.", "The experience is somewhat similar to a skateboarding experience, though, among other differences, in snowboarding a user's feet are fixedly attached to a board during use.", "After a run, a user releases one foot, normally the rear foot, and pushes with that foot to maneuver through chair lift lines and onto a chair lift.", "During the chair lift ride, the board dangles unbalanced and uncomfortably from the permanently attached foot.", "Upon exiting the chair lift, a user reattaches his or her free “foot”", "before descending a run.", "[0004] A need exists to alleviate the awkward and uncomfortable situation of having a board dangle from a user's foot during a chair lift ride.", "Several prior art devices are known that address this problem.", "They include the devices disclosed in U.S. Pat. No.: 6,349,968 issued to Owen;", "U.S. Pat. No. 5,951,048 issued to Slaughter;", "U.S. Pat. No. 5,564,729 issued to Gomez;", "U.S. Pat. No. 5,090,722 issued to Ritchie;", "U.S. Pat. No. 5,356,159 issued to Butterfield;", "and U.S. Pat. No. 6,247,728 issued to Verville.", "[0005] U.S. Pat. No. 6,349,968 to Owen teaches a cord with a releasable carbiner type clamp.", "This device is disadvantageous for several reasons including that if there is any problem with release, due to operator error or mechanical failure, the user is unreleasably coupled to the moving chair lift, potentially resulting in serious injury at unloading and/or stoppage of the lift apparatus.", "Also the extended cord does not lend itself to ready and secure stowage.", "[0006] Various other know devices, such as those disclosed in U.S. Pat. No.: 5,090,722 to Ritchie, U.S. Pat. No. 5,356,159 to Butterfield and U.S. Pat. No. 6,247,728 to Verville, illustrate positive engagement devices provided on boards, bindings or boots where the “free”", "foot is temporarily coupled to the board through the positive engagement device.", "These devices tend to be disadvantageous in that they may be difficult to use particularly in winter conditions where parts may frequently be clogged with snow or ice and cold fingers may loose the dexterity required for operation.", "Also, device reliability is questionable due in part to fouling or inherent design limitations in the devices or the object to which they attach, etc.", "Furthermore, while they may balance weight more evenly over two feet, the weight of the board and boots, etc.", ", is wholly supported by the legs not permitting leg muscles to rest more fully before the next run.", "[0007] A need thus exists for a mechanism for better supporting a snowboard or like device during chair lift or related transport.", "This need may include the need for a device that more evenly balances weight, can mount to a lift chair or other structure in a supportive, secure manner which is readily and inherently separable from the chair or structure, is readily and securely stowable when not in use and/or directly supports board weight permitting legs to rest, among other needs.", "[0008] Accordingly, it is an object of the present invention to provide these and related features or functionality.", "The attainment of these and related features and advantages should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention taken together with the drawings.", "BRIEF DESCRIPTION OF THE DRAWINGS [0009] FIG. 1 is a perspective view of one embodiment of a snowboard support device in accordance with the present invention is shown.", "[0010] FIG. 2 illustrates the device of FIG. 1 in a stowage position, while FIG. 3 illustrates the device in an extended position.", "[0011] FIGS. 4 and 5 perspective views the device of FIG. 1 at different levels of extension, while FIG. 6 is side elevation view of the device in the extended position.", "[0012] FIGS. 7-8 are exploded perspective views of the device of FIG. 1 and the top extension shaft of that device, respectively.", "[0013] FIGS. 9-10 are a top plan view and a side elevation view illustrating cam-based positioning of the handle and shaft, respectively, of the device of FIG. 1 .", "DETAILED DESCRIPTION [0014] Referring to FIG. 1 , a perspective view of a snowboard support device 50 in accordance with the present invention is shown.", "FIG. 1 illustrates device 50 in an extended position with handle/housing (“handle”) 23 resting on a chair lift seat 60 .", "Device 50 is preferably mounted to a snowboard 70 or other device through an extension 71 of binding plate 1 (shown in other figures) or other suitable means.", "Extension shaft 52 may be pivotally coupled to base 4 through a shuttle 6 movably mounted on shuttle shaft 5 .", "Extension shaft 52 may have a telescoping configuration and include a lower, middle and upper section 9 , 14 , 22 , respectively.", "Handle 23 may be pivotally coupled to upper section 22 and configured to not extend substantially past 90 degrees.", "[0015] FIG. 2 illustrates device 50 in a stowage position compactly contracted within handle 23 .", "FIG. 3 illustrates device 50 in an extended position.", "The base 4 , shuttle 6 and extension shaft 52 are visible in this view.", "The binding plate 1 and disk 2 , pivot arm 13 , release latch 24 and other features are also shown.", "[0016] Device 50 is preferably biased towards the extended position.", "To contract it, a user applies a downward force in the direction of arrow C to compress the shaft and then in the direction of arrow B to move the orientation of shaft 52 toward horizontal.", "Movement in the direction of arrow B causes the lower section of shaft 52 to pivot about pivot arm 13 and move via movement of shuttle 6 on shuttle shaft 5 (see FIG. 4 ) in the direction of arrow D. Handle 23 is moved generally downward in the direction of arrow A until it mounts on and “clicks”", "into base 4 .", "To extend the device, latch release mechanism 24 is actuated by a user which releases handle 23 from base 4 and permits a user to extend the handle to the extended position for resting on a chair lift seat as shown in FIG. 1 (and the handle is preferably biased towards this extended position).", "It should be recognized that by merely resting on the chair lift seat (as opposed to positively attaching such as with a clip or carbiner), the present invention is much less likely to become inadvertently attached to the chair lift.", "[0017] FIGS. 4-6 are three perspective views illustrating embodiments of device 50 at three different levels of extension.", "FIGS. 7-8 are two exploded perspective views that illustrate the various components of the embodiments of device 50 of FIGS. 4-6 .", "[0018] The mounting of a binding plate 1 to a board is known.", "For device 50 , an exterior region 71 is provided with binding plate 1 and clips 3 are used to mount base 4 to the binding plate.", "Shaft 5 is provided within the structure of base 4 and shuttle 6 is preferably configured for movement along shaft 5 .", "Spring 20 biases housing 6 away from a contracted position causing shaft 52 to rise up in response to a release of latch mechanism 24 (described below).", "Axle 7 facilitates pivotal coupling of shaft 52 to shuttle 6 .", "[0019] Pivot arm 13 is coupled to a pivot member 11 into which shuttle shaft 5 is inserted.", "These items are held in place by firmly secured base 4 .", "Pivot arm 13 is coupled to lower shaft section 9 .", "[0020] Extension shaft sections 9 , 14 , 22 telescope within each other.", "See, for example, FIG. 6 .", "A spring tempered anchor 36 is preferably provided in top section 22 to absorb shocks and some lateral movement.", "[0021] FIG. 8 illustrates details of the handle 23 and top shaft section 22 .", "Latch actuator 24 is movably coupled through pin 25 to handle 23 and further to internal latch 29 .", "Cam spring 28 biased latch 29 towards engagement.", "When handle 23 is pressed onto base 4 the teeth 30 of latch 29 hook underneath ledge 38 of base 4 (see FIG. 7 ).", "To release the handle from the base, latch actuator 24 is pushed forward causing the internal latch 29 to rotate such that teeth 30 disengage ledge 38 .", "Lock knob 27 in the straight up position blocks movement of latch 24 .", "[0022] Anchor 36 may include an axial screw 35 that mounts cam 32 and spring 33 to top shaft section 22 adjacent pin 31 .", "The spring and cam serve to center top shaft section 22 and provide some flexibility and shock absorption.", "[0023] FIGS. 9 and 10 illustrate features of the functionality of device 50 .", "The bottom two shaft sections are preferably configured such that they do not turn (though they may be configured otherwise without departing from the invention).", "The top shaft section 22 is preferably coupled through a cam arrangement that permits turning, but recenters in the absence of a turning force as discussed above with reference to FIG. 8 , and shown in FIG. 9 .", "FIG. 10 illustrates that the extension shaft may be provided with shuttle 6 and cam spring 20 ( FIG. 7 ) such that the shuttle is biased towards vertical with a certain amount of play.", "[0024] Components may be made of metal, plastic or other suitable materials.", "[0025] While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention and the limits of the appended claims." ]
BACKGROUND OF THE INVENTION The invention relates to a method of detecting a routing loop in a telecommunication network equipped with nodes, each containing node-specific routing information, in which a path is assembled from a source node, on the one hand, to a destination node, on the other hand, on the basis of the node-specific routing information associated with the source node and the node-specific routing information associated with the nodes situated on the path. Such a method is disclosed by U.S. Pat. No. 5,014,262. In the latter, two submethods are described: a first submethod for detecting a routing loop (call looping) and a second submethod for detecting inefficient routing (circuitous routing). The first submethod, which is carried out for each destination node, comprises four steps. In the first step, all the nodes which do not receive any traffic for the destination node are removed, and in the second step, all the nodes which do not transmit any traffic to the destination node are removed. These nodes which have to be removed can, after all, not form part of a routing loop. In the third step, all tee nodes which form part of so-called miniloops are dealt with. Two nodes form part of a miniloop if one of the nodes receives traffic for the destination node from the other node and the first node also transmits traffic to the other node. For technical reasons, a miniloop can never occur as a routing loop because, at the position of a node, which preceding node the traffic to be routed further originates from is known and said traffic will never, of course, need to be sent back to said previous node. In the fourth step, the nodes which do not form part of a routing loop are identified. Such a node must, for example, meet the criterion that, if the node transmits traffic to another node, said other node must not send any traffic back to the node concerned. How this criterion, which in fact only states in other words that no routing loop must be possible, must be met is unclear. One solution could be to investigate for all the nodes left over after the first three steps whether the node which has the most incoming and outgoing traffic and transmits traffic to particular nodes receives traffic back from said particular nodes via a longer path. The said node would then have to be removed and the remaining nodes would have to be investigated again, etc. Like the criterion stated, such investigations are, however, yet another formulation of the problem of detecting routing loops. This known method, which is in any case cumbersome and, consequently, time-consuming, furthermore has the disadvantage that it is uncertain whether existing routing loops are found with it. SUMMARY OF THE INVENTION The object of the invention is, inter alia, to provide a method of the type stated at the outset which is less cumbersome and detects the existence of routing loops with a probability bordering on certainty. For this purpose, the method according to the invention has the characteristic that, during the assembly of a path, a parameter of said path is increased at each subsequent node situated on said path by one unit, the parameter, expressed in a number of units, of a partly assembled path being compared with a predetermined value and a partly assembled path whose parameter exceeds said value being detected as a path containing a routing loop. The value of the parameter of the partly assembled path, expressed in the number of units, is at any instant equal to a number of connecting pieces which together forms said partly assembled path at that instant. Increasing the parameter by one unit at each subsequent node situated on the path is in this case equivalent to counting the number of connecting pieces, one connecting piece being a portion of the path situated between two consecutive nodes. Said parameter which, at an arbitrary instant, therefore specifies the length of the path assembled at that instant, is an indication of the existence of a routing loop. If the length of a partly assembled path, expressed in the number of connecting pieces which together forms the partly assembled path, exceeds the predetermined value, it can be concluded with a probability bordering on certainty that a routing loop exists. Said predetermined value could, for example, be chosen as equal to the total number of nodes which form part of the telecommunication network, or to a smaller value if said telecommunication network has a heavily meshed nature. The invention is based on the insight that., in any telecommunication network, there must be one or more paths which have the greatest length and that, as soon as the length determined for a (partly assembled) path exceeds said greatest length, this would be the consequence of the presence of a routing loop in the said (partly assembled) path. Although U.S. Pat. No. 5,014,262 discloses the detection of inefficient routing (circuitous routing) (with the aid of the second submethod mentioned earlier) by determining the length of an assembled path and then investigating whether said length is greater than necessary, which is done by comparing the length with a nominal value associated with the path, the U.S. Patent does not disclose the detection of a routing loop by determining the length of a (partly assembled) path and comparing it with the predetermined value, which is greater than, or equal to, the greatest possible path length in the telecommunication network. The method according to the invention consequently solves a problem which has existed for a long time and which is of great importance in view of the regular failure of large telecommunication networks in past years as a result of the existence of routing loops. In a first embodiment, the method according to the invention has the characteristic that, of two nodes which are situated on the path to be assembled and which each have a direct routing possibility to the other in their routing information, not more than one of the two routing possibilities is used in assembling the path. Two nodes which each have a direct routing possibility to the other in their routing information form a so-called miniloop, which can never occur as a routing loop for the technical reasons mentioned earlier. The first embodiment of the method according to the invention takes account of this by using not more than one of the two routing possibilities. In a second embodiment, the method according to the invention has the characteristic that all the nodes function consecutively as destination nodes, all the remaining nodes consecutively functioning as source node for each destination node. In this process, all the paths between, on the one hand, all the possible source nodes and, on the other hand, all the possible destination nodes are investigated for the existence of routing loops. This can be done by assembling all the possible paths from one source node to the destination node and repeating this operation for all the remaining source nodes. It is also possible first to try to reach the destination node from the source nodes with a path to be formed of length 1 and then to repeat this operation for all the source nodes with a length which increases each time. The invention furthermore relates to a telecommunication network for using the method according to the invention, equipped with nodes which each contain node-specific routing information, and detection means containing path assembly means for assembling a path from a source node, on the one hand, to a destination node, on the other hand, on the basis of the node-specific routing information associated with the source node and the node-specific routing information associated with nodes situated on the path. The object of the invention is furthermore to provide a telecommunication network of the type described above which detects the existence of routing loops in a nonlaborious way with a probability bordering on certainty. For this purpose, the telecommunication network according to the invention has the characteristic that the detection means are further equipped with counting means for increasing a counter position by one counting unit at each subsequent node situated on a path during the assembly of said path, and comparator means for comparing the counter position associated with a partly assembled path with a predetermined counter value and for generating an alarm signal in the event of it being exceeded. In this connection, the counter position of the counting means, expressed in a number of counter units, is equivalent to the number of connecting pieces which together forms the (partly assembled) path and therefore specifies the length of said path. The comparator means are used to compare the counter position, and consequently the length of the partly assembled path, with the predetermined counter value which is greater than, or equal to, the path length which is the greatest possible in the telecommunication network and can be chosen, for example, as equal to the total number of nodes which form part of the telecommunication network. The alarm signal to be generated in the event of it being exceeded indicates the existence of a routing loop with a probability bordering on certainty. In a first embodiment, the telecommunication network according to the invention has the characteristic that the detection means are equipped with ignoring means for ignoring at least one of the two routing possibilities in the assembly of a path in the case of two nodes which are situated on the path to be assembled and which each have a direct routing possibility to the other in their routing information. Two such nodes which each have a direct routing possibility to the other in their routing information form a so-called miniloop which can never occur as a routing loop, as already described above. The first embodiment of the telecommunication system according to the invention comprises ignoring means for ignoring at least one of the two routing possibilities. In a second embodiment, the telecommunication system according to the invention has the characteristic that the detection means are provided with selection means for successively selecting all the nodes as the destination node and for successively selecting all the remaining nodes as the source nodes for each destination node selected. By using the selection means, all the paths in the telecommunication network between, on the one hand, all the possible source nodes and, on the other hand, all the possible destination nodes are investigated for the existence of routing loops. The invention furthermore also relates to a detection system for use in the telecommunication system according to the invention, comprising path assembly means for assembling a path from a source node, on the one hand, to a destination node, on the other hand, on the basis of the node-specific routing information associated with the source node and the node-specific routing information associated with the nodes situated on the path. The detection means according to the invention have the characteristic that the detection means are furthermore equipped with counting means for increasing a counter position by one counting unit at each subsequent node situated on a path during the assembly of said path, and comparator means for comparing the counter position associated with a partly assembled path with a predetermined counter value and for generating an alarm signal in the event of it being exceeded. In a first embodiment, the detection means according to the invention have the characteristic that they are equipped with ignoring means for ignoring at least one of the two routing possibilities in the assembly of a path in the case of two nodes which are situated on the path to be assembled and which each have a direct routing possibility to the other in their routing information. In a second embodiment, the detection means according to the invention have the characteristic that the detection means are provided with selection means for successively selecting all the nodes as the destination node and for successively selecting all the remaining nodes as the source node for each destination node selected. The detection of a routing loop in the telecommunication network by assembling paths and then investigating whether the length of said paths exceeds a particular value can take place either by actually assembling paths or by assembling paths in a simulated manner. In the first case, the assembly is actually done on the basis of node-specific routing information associated with the nodes, while, in the second case, use could also be made of central memory means in which the node-specific routing information of all the nodes is stored. BRIEF DESCRIPTION OF THE DRAWING The invention will be explained in greater detail by reference to an exemplary embodiment shown in the figures. In the latter: FIG. 1 shows a flow chart of an embodiment of the method according to the invention, FIGS. 2, 3 shows a telecommunication network according to the invention equipped with nodes and detection means which detect a routing loop, and FIG. 4 shows a more detailed reproduction of the detection means. DESCRIPTION OF THE PREFERRED EMBODIMENT In the flow chart shown in FIG. 1, the blocks have the following meaning: ______________________________________Block 1 define new destination nodeBlock 2 define new source nodeBlock 3 t: = 0Block 4 determine the subsequent node situated on the path for each possible path between the source node and the destination node, in which process miniloops should be avoided, store the subsequent nodes found in this way along with an associated value of t and treat them in the order of priorityBlock 5 t: = t + 1Block 6 is the node being dealt with the destination node? yes: proceed to block 7 no: proceed to block 8Block 7 store the path found along with associated length tBlock 8 is t ≧ x? yes: proceed to block 9 no: return to block 4Block 9 generate alarm signal, routing loop detectedBlock 10 are there still remaining nodes (block 4) to be dealt with? yes: return to block 5 no: proceed to block 11Block 11 have all the possible other nodes been defined as a source node in the case of the destination node defined? yes: proceed to block 12 no: return to block 2Block 12 have all the possible nodes been defined as a destination node? yes: proceed to block 13 no: return to block 1Block 13 list all the paths found, each with associated length t, and all the routing loops detected, each with associated source node and destination node.______________________________________ The method according to the invention as shown in the flow chart in FIG. 1 proceeds as follows. A destination node is chosen from all the nodes associated with the telecommunication network (block 1). For said destination node, a source node is then chosen from the remaining nodes (block 2) and a parameter t acquires the value 0 (block 3). On the basis of the node-specific routing information of the source node, for each possible path between the source node and the destination node, the subsequent node situated on said path is determined, miniloops being avoided (that is to say of two nodes which each have a direct routing possibility to the other, only one of said routing possibilities is used in the assembly of the path). All nodes found in this way are stored along with the associated value of t and dealt with in order of priority (block 4). The parameter t is increased by one unit (block 5) and whether it coincides with the destination node is investigated for the node point found with the highest priority (block 6). In the event of coincidence, a path has been found which is stored with the associated value of t which reproduces the length of said path, expressed in the number of connecting pieces which, in its entirety, forms the path (block 7). In the event of noncoincidence, whether the parameter t is greater than, or equal to, a predetermined value x is investigated (block 8). If this is so, a routing loop has been detected and an alarm signal is generated (block 9), and if this is not so, for each possible path between said node and the destination node, the subsequent node is determined on said path on the basis of the node-specific routing information of the highest-priority node found until all the possible paths between the highest-priority node found and the destination node have been assembled and any routing loops present have been detected. Whether there are still remaining lower-priority nodes (cf. block 4) which have to be dealt with is then investigated (block 10). If these exist, they are again dealt with in order of priority, that is to say, for the highest-priority node of these remaining nodes, the parameter t is increased by one unit and whether it coincides with the destination node is investigated, etc., and if there are no remaining nodes present, whether all the nodes other than the definition node have already been defined as source node is examined (block 11). If this is not so, another node which has not yet been under discussion in the case of the given destination node is defined as source node, etc. (block 2), and if this is in fact so, whether all the nodes have already been defined as the destination node is investigated (block 12). If this is not so, another node which has not vet been under discussion is defined as the destination node, etc. (block 1), and if this is in fact so, a list is shown of all the paths found, each with associated length t, and of all the detected routing loops, each with associated source node and destination node (block 13). It is pointed out that increasing the parameter t for each subsequent node situated on the path should be interpreted in a wide sense. Thus, for example, it is also already possible to increase the parameter t on ascending a subsequent connecting piece situated between two nodes, and the possibility must furthermore not be excluded that each new path is started with a fixed value for the parameter t in order subsequently to reduce said value for each subsequent node or connecting piece and, for example, to detect a routing loop with the value 0 (a disadvantage in this connection is that, in this case, the length of the path assembled is not directly available). The exemplary embodiment described above on the basis of FIG. 1 relates to a method which could be used, for example, in the simulated assembly of paths. In the actual assembly of paths on the basis of the node-specific routing information associated with the nodes, use could also be made of a variation of this exemplary embodiment in which, for a given destination node, whether the destination node can be reached with paths of length 1 is first investigated from a particular source node, and whether the destination node can be reached from the source node with paths having a greater length is then investigated on the basis of the data determined above, which last operation is continuously repeated with steadily increasing length until, finally, either it is no longer possible to assemble paths having a greater length or the length of the path last assembled exceeds the predetermined value x, in which case a detection of a routing loop is involved. In this case, the value x is greater than the largest possible path length in the telecommunication network and is, for example, equal to the number of nodes present therein. The telecommunication network 20 shown in FIGS. 2 and 3 contains detection means 21 and nodes 30 to 41, inclusive. In FIG. 2, the routing possibilities from the source node 39 to the destination node 32 are shown. The nodes 39 and 36 have a direct, unidirectional routing possibility from the node 39 mentioned first to the node 36 mentioned last. The same applies to the nodes 36 and 37, 37 and 35 and 35 and 32. In FIG. 3, the routing possibilities from the source node 32 to the destination node 39 are shown. The nodes 32 and 35 have a direct unidirectional routing possibility from the node 32 mentioned first to the node 35 mentioned last. The same applies to the nodes 35 and 31, 31 and 30, 30 and 34, 33 and 36, 34 and 37, 37 and 36, and 36 and 39. The nodes 30 and 33 each have a mutual, direct, bidirectional routing possibility to the other and form a so-called miniloop. The same applies to the nodes 33 and 34. The assembly of a path from source node 39 to destination node 32 as shown in FIG. 2 proceeds as follows. In the node-specific routing information of source node 39, the node 36 is found as the subsequent node situated on the path for the given destination node 32. The parameter t acquires the value 1. Node 36 does not coincide with the destination node 32 and the value of the parameter t is less than the predetermined value which, for this telecommunication network 20, could be set at the value 12 (the number of nodes) or at the value 9 (the largest path length plus 1). In the node-specific routing information of node 36, the node 37 is found as the subsequent node situated on the path for the given destination node 32. The parameter t acquires the value 2. Node 37 does not coincide with the destination node 32 and the value of the parameter t is less than the predetermined value 9. In the node-specific routing information of node 37, the node 35 is found as the subsequent node situated on the path for the given destination node 32. The parameter t acquires the value 3. Node 35 does not coincide with the destination node 32 and the value of the parameter t is less than the predetermined value 9. In the node-specific routing information of node 35, the node 32 is found as the subsequent node situated on the path for the given destination node 32. The parameter t acquires the value 4. Node 32 is the destination node 32 and the path from source node 39 to destination node 32 via the nodes 36, 37 and 35 and having length 4 has consequently been found. No routing loop exists in this path. The assembly of a path from source node 32 to destination node 39 as shown in FIG. 3, in which case a routing loop will be detected, proceeds as follows. In the node-specific routing information of source node 32, the node 35 is found as the subsequent node situated in the path for the given destination node 39. The parameter t acquires the value 1. Node 35 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9. In the node-specific routing information of node 35, the node 31 is found as the subsequent node situated on the path for the given destination node 39. The parameter t acquires the value 2. Node 31 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9. In the node-specific routing information of node 31, the node 30 is found as the subsequent node situated on the path for the given destination node 39. The parameter t acquires the value 3. Node 30 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9. In the node-specific routing information of node 30, two subsequent nodes situated on different paths, namely node 33 and 34, are found for the given destination node 39 because four different paths are possible from the node 30 to the destination node 39: a first path via node; 33 and 36, a second path via node 33, 34, 37 and 36, which two paths therefore yield the node 33 as the subsequent node, a third path via node 34, 37 and 36, and a fourth path via 34, 33 and 36, which two paths therefore yield the node 34 as the subsequent node. For both nodes, the parameter t acquires the value 4. Assuming that, of the nodes 33 and 34, the node 33 has the highest priority, the paths via this node are first assembled. In the node-specific routing information of node 33, two subsequent nodes situated on different paths, namely node 36 on the first path and node 34 on the second path, are found for the given destination node 39, and depending on the priority of said nodes 36 and 34, which dc not coincide with the destination node 39, both paths are further assembled in a particular order. For both nodes 36 and 34, the parameter t acquires the value 5. In the node-specific routing information of node 36, the node 39 is found as the subsequent node situated on the path for the given destination node 39. The parameter t acquires the value 6. Node 39 is the destination node 39 and the path from source node 32 to destination node 39 via the nodes 35, 31, 30, 33 and 36 and having length 6 has consequently been found. A routing loop does not exist in this first path. In the node-specific routing information of node 34, the node 37 is found as the subsequent node situated on the path for the given destination node 39. The parameter t acquires the value 6. Node 37 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9. In the node-specific routing information of node 37, the node 36 is found as the subsequent node situated on the path for the given destination node 39. The parameter t acquires the value 7. Node 36 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9. In the node-specific routing information of node 36, the node 39 is found as the subsequent node situated on the path for the given destination node 39. The parameter t acquires the value 8. Node 39 is the destination node 39 and the path from source node 32 to destination node 39 via the nodes 35, 31, 30, 33, 34, 37, 36 and 39 and having a length 8 has consequently been found. A routing loop does not exist in this second path. After the paths via node 33 have been assembled, the paths via node 34 are assembled. In the node-specific routing information of node 34 two subsequent nodes situated on different paths, namely node 37 on the third path and node 33 on the fourth path, are found with the given destination node 39, and depending on the priority of said nodes 37 and 33, which do not coincide with the destination node 39, both paths are assembled further in a particular order. For both nodes 37 and 33, the parameter t acquires the value 5. In the node-specific routing information of node 37, the node 36 is found as the subsequent node situated on the path for the given destination node. The parameter t acquires the value 6. Node 36 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9. In the node-specific routing information of node 36, the node 39 is found as the subsequent node situated on the path for the given destination node. The parameter t acquires the value 7. Node 39 is the destination node 39, and the path from source node 32 to destination node 39 via nodes 35, 31, 30, 34, 37 and 36 and having a length 7 has consequently been found. A routing loop does not exist in this third path. In the node-specific routing information of node 33, two subsequent nodes situated on different paths, namely nodes 36 and 30, are found for the given destination node 39, and depending on the priority of said nodes 36 and 30, which do not coincide with the destination node 39, both paths are assembled further in a particular order. For both nodes 36 and 30, the parameter t acquires the value 6. The fourth path therefore appears to contain different paths which have been split up. In the node-specific routing information of node 36, the node 39 is found as the subsequent node situated on the path for the given destination node 39. The parameter t acquires the value 7. Node 39 is the destination node 39, and the path from source node 32 to destination node 39 via nodes 35, 31, 30, 34, 33 and 36 and having a length 7 has consequently been found. A routing loop does not exist in this splitting-up of the fourth path. In the node-specific routing information of node 30, the node 34 is found as the subsequent node situated on the path for the given destination node 39. The parameter t acquires the value 7. Node 34 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9. In the node-specific routing information of node 34, two subsequent nodes situated on different paths, namely node 37 and 33, are found as before, for the given destination node 39, and depending on the priority of said nodes 37 and 33, which do not coincide with the destination node 39, both paths are assembled further in a particular order. For both nodes 37 and 33, the parameter t acquires the value 8. From whichever of the paths 37 and 33 a path is now assembled further (and how a path, if any, is assembled from node 33) is irrelevant: before the destination node 39 is reached, the parameter t acquires the value 9, which indicates the existence of a routing loop in the partly assembled path. This loop comprises the nodes 30, 34, 33, 30, 34 etc. and could be eliminated in a simple manner either by eliminating the unidirectional routing possibility from node 30 to 34 and, as a consequence thereof, the unidirectional routing possibility from node 33 to 34 and from node 34 To node 33, in which case the routing possibilities in the opposite direction between the four nodes mentioned last should continue to exist, or by eliminating only the unidirectional routing possibility from node 33 to 30, in which case the routing possibility in the opposite direction between the nodes mentioned last should continue to exist. The detection means 21 shown in FIG. 4 comprise path assembly means 22 for assembling a path from a source node, on the one hand, to a destination node, on the other hand, on the basis of the node-specific routing information associated with the source node and the node-specific routing information associated with the nodes situated on the path. Path assembly means 22 are coupled to memory means 23 in which the node-specific routing information is stored, and they are coupled to counting means 24 for increasing a counter position by one counter unit at each subsequent node situated on a path during the assembly of said path. For this purpose, counting means 24 receive, from path assembly means 22, a counting pulse at a first input and a counter position, to be loaded and associated with a particular node, at a second input. An output of the counting means 24 is coupled to a first input of comparator means 25 for comparing the counter position associated with a partly assembled path with a predetermined counter value and for generating an alarm system in the event of it being exceeded, the predetermined counter value x being stored in memory means 26, which are coupled to a second input of comparator means 25. An output of comparator means 25 is coupled to path assembly means 22 for supplying the alarm signal. Path assembly means 22 are furthermore coupled to selection means 27 for successively selecting all the nodes as the destination node and for successively selecting all the remaining nodes as the source nodes for each destination node selected, and to ignoring means 28 for ignoring at least one of the two routing possibilities in the assembly of a path in the case of two nodes which are situated on the path to be assembled and which each have a direct routing possibility to the other in their routing information. In this connection, memory means 23 reproduce the memories of all the nodes symbolically if a routing loop is to be detected by actually assembling the path. If a routing loop is to be detected by assembling paths in a simulated manner, memory means 23 could also be formed by a central memory in which the node-specific routing information of all the nodes is stored.
Known methods of detecting routing loops in telecommunication networks are cumbersome and time-consuming. In addition, the probability that an existing routing loop is even actually detected is too low. In a method of detecting a routing loop according to the invention, paths whose lengths are stored are assembled. As soon as the length of a (partly assembled) path exceeds a predetermined value which is greater than, or equal to, the largest existing path length in the telecommunication network, this indicates the existence of a routing loop.
Concisely explain the essential features and purpose of the concept presented in the passage.
[ "BACKGROUND OF THE INVENTION The invention relates to a method of detecting a routing loop in a telecommunication network equipped with nodes, each containing node-specific routing information, in which a path is assembled from a source node, on the one hand, to a destination node, on the other hand, on the basis of the node-specific routing information associated with the source node and the node-specific routing information associated with the nodes situated on the path.", "Such a method is disclosed by U.S. Pat. No. 5,014,262.", "In the latter, two submethods are described: a first submethod for detecting a routing loop (call looping) and a second submethod for detecting inefficient routing (circuitous routing).", "The first submethod, which is carried out for each destination node, comprises four steps.", "In the first step, all the nodes which do not receive any traffic for the destination node are removed, and in the second step, all the nodes which do not transmit any traffic to the destination node are removed.", "These nodes which have to be removed can, after all, not form part of a routing loop.", "In the third step, all tee nodes which form part of so-called miniloops are dealt with.", "Two nodes form part of a miniloop if one of the nodes receives traffic for the destination node from the other node and the first node also transmits traffic to the other node.", "For technical reasons, a miniloop can never occur as a routing loop because, at the position of a node, which preceding node the traffic to be routed further originates from is known and said traffic will never, of course, need to be sent back to said previous node.", "In the fourth step, the nodes which do not form part of a routing loop are identified.", "Such a node must, for example, meet the criterion that, if the node transmits traffic to another node, said other node must not send any traffic back to the node concerned.", "How this criterion, which in fact only states in other words that no routing loop must be possible, must be met is unclear.", "One solution could be to investigate for all the nodes left over after the first three steps whether the node which has the most incoming and outgoing traffic and transmits traffic to particular nodes receives traffic back from said particular nodes via a longer path.", "The said node would then have to be removed and the remaining nodes would have to be investigated again, etc.", "Like the criterion stated, such investigations are, however, yet another formulation of the problem of detecting routing loops.", "This known method, which is in any case cumbersome and, consequently, time-consuming, furthermore has the disadvantage that it is uncertain whether existing routing loops are found with it.", "SUMMARY OF THE INVENTION The object of the invention is, inter alia, to provide a method of the type stated at the outset which is less cumbersome and detects the existence of routing loops with a probability bordering on certainty.", "For this purpose, the method according to the invention has the characteristic that, during the assembly of a path, a parameter of said path is increased at each subsequent node situated on said path by one unit, the parameter, expressed in a number of units, of a partly assembled path being compared with a predetermined value and a partly assembled path whose parameter exceeds said value being detected as a path containing a routing loop.", "The value of the parameter of the partly assembled path, expressed in the number of units, is at any instant equal to a number of connecting pieces which together forms said partly assembled path at that instant.", "Increasing the parameter by one unit at each subsequent node situated on the path is in this case equivalent to counting the number of connecting pieces, one connecting piece being a portion of the path situated between two consecutive nodes.", "Said parameter which, at an arbitrary instant, therefore specifies the length of the path assembled at that instant, is an indication of the existence of a routing loop.", "If the length of a partly assembled path, expressed in the number of connecting pieces which together forms the partly assembled path, exceeds the predetermined value, it can be concluded with a probability bordering on certainty that a routing loop exists.", "Said predetermined value could, for example, be chosen as equal to the total number of nodes which form part of the telecommunication network, or to a smaller value if said telecommunication network has a heavily meshed nature.", "The invention is based on the insight that.", ", in any telecommunication network, there must be one or more paths which have the greatest length and that, as soon as the length determined for a (partly assembled) path exceeds said greatest length, this would be the consequence of the presence of a routing loop in the said (partly assembled) path.", "Although U.S. Pat. No. 5,014,262 discloses the detection of inefficient routing (circuitous routing) (with the aid of the second submethod mentioned earlier) by determining the length of an assembled path and then investigating whether said length is greater than necessary, which is done by comparing the length with a nominal value associated with the path, the U.S. Patent does not disclose the detection of a routing loop by determining the length of a (partly assembled) path and comparing it with the predetermined value, which is greater than, or equal to, the greatest possible path length in the telecommunication network.", "The method according to the invention consequently solves a problem which has existed for a long time and which is of great importance in view of the regular failure of large telecommunication networks in past years as a result of the existence of routing loops.", "In a first embodiment, the method according to the invention has the characteristic that, of two nodes which are situated on the path to be assembled and which each have a direct routing possibility to the other in their routing information, not more than one of the two routing possibilities is used in assembling the path.", "Two nodes which each have a direct routing possibility to the other in their routing information form a so-called miniloop, which can never occur as a routing loop for the technical reasons mentioned earlier.", "The first embodiment of the method according to the invention takes account of this by using not more than one of the two routing possibilities.", "In a second embodiment, the method according to the invention has the characteristic that all the nodes function consecutively as destination nodes, all the remaining nodes consecutively functioning as source node for each destination node.", "In this process, all the paths between, on the one hand, all the possible source nodes and, on the other hand, all the possible destination nodes are investigated for the existence of routing loops.", "This can be done by assembling all the possible paths from one source node to the destination node and repeating this operation for all the remaining source nodes.", "It is also possible first to try to reach the destination node from the source nodes with a path to be formed of length 1 and then to repeat this operation for all the source nodes with a length which increases each time.", "The invention furthermore relates to a telecommunication network for using the method according to the invention, equipped with nodes which each contain node-specific routing information, and detection means containing path assembly means for assembling a path from a source node, on the one hand, to a destination node, on the other hand, on the basis of the node-specific routing information associated with the source node and the node-specific routing information associated with nodes situated on the path.", "The object of the invention is furthermore to provide a telecommunication network of the type described above which detects the existence of routing loops in a nonlaborious way with a probability bordering on certainty.", "For this purpose, the telecommunication network according to the invention has the characteristic that the detection means are further equipped with counting means for increasing a counter position by one counting unit at each subsequent node situated on a path during the assembly of said path, and comparator means for comparing the counter position associated with a partly assembled path with a predetermined counter value and for generating an alarm signal in the event of it being exceeded.", "In this connection, the counter position of the counting means, expressed in a number of counter units, is equivalent to the number of connecting pieces which together forms the (partly assembled) path and therefore specifies the length of said path.", "The comparator means are used to compare the counter position, and consequently the length of the partly assembled path, with the predetermined counter value which is greater than, or equal to, the path length which is the greatest possible in the telecommunication network and can be chosen, for example, as equal to the total number of nodes which form part of the telecommunication network.", "The alarm signal to be generated in the event of it being exceeded indicates the existence of a routing loop with a probability bordering on certainty.", "In a first embodiment, the telecommunication network according to the invention has the characteristic that the detection means are equipped with ignoring means for ignoring at least one of the two routing possibilities in the assembly of a path in the case of two nodes which are situated on the path to be assembled and which each have a direct routing possibility to the other in their routing information.", "Two such nodes which each have a direct routing possibility to the other in their routing information form a so-called miniloop which can never occur as a routing loop, as already described above.", "The first embodiment of the telecommunication system according to the invention comprises ignoring means for ignoring at least one of the two routing possibilities.", "In a second embodiment, the telecommunication system according to the invention has the characteristic that the detection means are provided with selection means for successively selecting all the nodes as the destination node and for successively selecting all the remaining nodes as the source nodes for each destination node selected.", "By using the selection means, all the paths in the telecommunication network between, on the one hand, all the possible source nodes and, on the other hand, all the possible destination nodes are investigated for the existence of routing loops.", "The invention furthermore also relates to a detection system for use in the telecommunication system according to the invention, comprising path assembly means for assembling a path from a source node, on the one hand, to a destination node, on the other hand, on the basis of the node-specific routing information associated with the source node and the node-specific routing information associated with the nodes situated on the path.", "The detection means according to the invention have the characteristic that the detection means are furthermore equipped with counting means for increasing a counter position by one counting unit at each subsequent node situated on a path during the assembly of said path, and comparator means for comparing the counter position associated with a partly assembled path with a predetermined counter value and for generating an alarm signal in the event of it being exceeded.", "In a first embodiment, the detection means according to the invention have the characteristic that they are equipped with ignoring means for ignoring at least one of the two routing possibilities in the assembly of a path in the case of two nodes which are situated on the path to be assembled and which each have a direct routing possibility to the other in their routing information.", "In a second embodiment, the detection means according to the invention have the characteristic that the detection means are provided with selection means for successively selecting all the nodes as the destination node and for successively selecting all the remaining nodes as the source node for each destination node selected.", "The detection of a routing loop in the telecommunication network by assembling paths and then investigating whether the length of said paths exceeds a particular value can take place either by actually assembling paths or by assembling paths in a simulated manner.", "In the first case, the assembly is actually done on the basis of node-specific routing information associated with the nodes, while, in the second case, use could also be made of central memory means in which the node-specific routing information of all the nodes is stored.", "BRIEF DESCRIPTION OF THE DRAWING The invention will be explained in greater detail by reference to an exemplary embodiment shown in the figures.", "In the latter: FIG. 1 shows a flow chart of an embodiment of the method according to the invention, FIGS. 2, 3 shows a telecommunication network according to the invention equipped with nodes and detection means which detect a routing loop, and FIG. 4 shows a more detailed reproduction of the detection means.", "DESCRIPTION OF THE PREFERRED EMBODIMENT In the flow chart shown in FIG. 1, the blocks have the following meaning: ______________________________________Block 1 define new destination nodeBlock 2 define new source nodeBlock 3 t: = 0Block 4 determine the subsequent node situated on the path for each possible path between the source node and the destination node, in which process miniloops should be avoided, store the subsequent nodes found in this way along with an associated value of t and treat them in the order of priorityBlock 5 t: = t + 1Block 6 is the node being dealt with the destination node?", "yes: proceed to block 7 no: proceed to block 8Block 7 store the path found along with associated length tBlock 8 is t ≧ x?", "yes: proceed to block 9 no: return to block 4Block 9 generate alarm signal, routing loop detectedBlock 10 are there still remaining nodes (block 4) to be dealt with?", "yes: return to block 5 no: proceed to block 11Block 11 have all the possible other nodes been defined as a source node in the case of the destination node defined?", "yes: proceed to block 12 no: return to block 2Block 12 have all the possible nodes been defined as a destination node?", "yes: proceed to block 13 no: return to block 1Block 13 list all the paths found, each with associated length t, and all the routing loops detected, each with associated source node and destination node.", "______________________________________ The method according to the invention as shown in the flow chart in FIG. 1 proceeds as follows.", "A destination node is chosen from all the nodes associated with the telecommunication network (block 1).", "For said destination node, a source node is then chosen from the remaining nodes (block 2) and a parameter t acquires the value 0 (block 3).", "On the basis of the node-specific routing information of the source node, for each possible path between the source node and the destination node, the subsequent node situated on said path is determined, miniloops being avoided (that is to say of two nodes which each have a direct routing possibility to the other, only one of said routing possibilities is used in the assembly of the path).", "All nodes found in this way are stored along with the associated value of t and dealt with in order of priority (block 4).", "The parameter t is increased by one unit (block 5) and whether it coincides with the destination node is investigated for the node point found with the highest priority (block 6).", "In the event of coincidence, a path has been found which is stored with the associated value of t which reproduces the length of said path, expressed in the number of connecting pieces which, in its entirety, forms the path (block 7).", "In the event of noncoincidence, whether the parameter t is greater than, or equal to, a predetermined value x is investigated (block 8).", "If this is so, a routing loop has been detected and an alarm signal is generated (block 9), and if this is not so, for each possible path between said node and the destination node, the subsequent node is determined on said path on the basis of the node-specific routing information of the highest-priority node found until all the possible paths between the highest-priority node found and the destination node have been assembled and any routing loops present have been detected.", "Whether there are still remaining lower-priority nodes (cf.", "block 4) which have to be dealt with is then investigated (block 10).", "If these exist, they are again dealt with in order of priority, that is to say, for the highest-priority node of these remaining nodes, the parameter t is increased by one unit and whether it coincides with the destination node is investigated, etc.", ", and if there are no remaining nodes present, whether all the nodes other than the definition node have already been defined as source node is examined (block 11).", "If this is not so, another node which has not yet been under discussion in the case of the given destination node is defined as source node, etc.", "(block 2), and if this is in fact so, whether all the nodes have already been defined as the destination node is investigated (block 12).", "If this is not so, another node which has not vet been under discussion is defined as the destination node, etc.", "(block 1), and if this is in fact so, a list is shown of all the paths found, each with associated length t, and of all the detected routing loops, each with associated source node and destination node (block 13).", "It is pointed out that increasing the parameter t for each subsequent node situated on the path should be interpreted in a wide sense.", "Thus, for example, it is also already possible to increase the parameter t on ascending a subsequent connecting piece situated between two nodes, and the possibility must furthermore not be excluded that each new path is started with a fixed value for the parameter t in order subsequently to reduce said value for each subsequent node or connecting piece and, for example, to detect a routing loop with the value 0 (a disadvantage in this connection is that, in this case, the length of the path assembled is not directly available).", "The exemplary embodiment described above on the basis of FIG. 1 relates to a method which could be used, for example, in the simulated assembly of paths.", "In the actual assembly of paths on the basis of the node-specific routing information associated with the nodes, use could also be made of a variation of this exemplary embodiment in which, for a given destination node, whether the destination node can be reached with paths of length 1 is first investigated from a particular source node, and whether the destination node can be reached from the source node with paths having a greater length is then investigated on the basis of the data determined above, which last operation is continuously repeated with steadily increasing length until, finally, either it is no longer possible to assemble paths having a greater length or the length of the path last assembled exceeds the predetermined value x, in which case a detection of a routing loop is involved.", "In this case, the value x is greater than the largest possible path length in the telecommunication network and is, for example, equal to the number of nodes present therein.", "The telecommunication network 20 shown in FIGS. 2 and 3 contains detection means 21 and nodes 30 to 41, inclusive.", "In FIG. 2, the routing possibilities from the source node 39 to the destination node 32 are shown.", "The nodes 39 and 36 have a direct, unidirectional routing possibility from the node 39 mentioned first to the node 36 mentioned last.", "The same applies to the nodes 36 and 37, 37 and 35 and 35 and 32.", "In FIG. 3, the routing possibilities from the source node 32 to the destination node 39 are shown.", "The nodes 32 and 35 have a direct unidirectional routing possibility from the node 32 mentioned first to the node 35 mentioned last.", "The same applies to the nodes 35 and 31, 31 and 30, 30 and 34, 33 and 36, 34 and 37, 37 and 36, and 36 and 39.", "The nodes 30 and 33 each have a mutual, direct, bidirectional routing possibility to the other and form a so-called miniloop.", "The same applies to the nodes 33 and 34.", "The assembly of a path from source node 39 to destination node 32 as shown in FIG. 2 proceeds as follows.", "In the node-specific routing information of source node 39, the node 36 is found as the subsequent node situated on the path for the given destination node 32.", "The parameter t acquires the value 1.", "Node 36 does not coincide with the destination node 32 and the value of the parameter t is less than the predetermined value which, for this telecommunication network 20, could be set at the value 12 (the number of nodes) or at the value 9 (the largest path length plus 1).", "In the node-specific routing information of node 36, the node 37 is found as the subsequent node situated on the path for the given destination node 32.", "The parameter t acquires the value 2.", "Node 37 does not coincide with the destination node 32 and the value of the parameter t is less than the predetermined value 9.", "In the node-specific routing information of node 37, the node 35 is found as the subsequent node situated on the path for the given destination node 32.", "The parameter t acquires the value 3.", "Node 35 does not coincide with the destination node 32 and the value of the parameter t is less than the predetermined value 9.", "In the node-specific routing information of node 35, the node 32 is found as the subsequent node situated on the path for the given destination node 32.", "The parameter t acquires the value 4.", "Node 32 is the destination node 32 and the path from source node 39 to destination node 32 via the nodes 36, 37 and 35 and having length 4 has consequently been found.", "No routing loop exists in this path.", "The assembly of a path from source node 32 to destination node 39 as shown in FIG. 3, in which case a routing loop will be detected, proceeds as follows.", "In the node-specific routing information of source node 32, the node 35 is found as the subsequent node situated in the path for the given destination node 39.", "The parameter t acquires the value 1.", "Node 35 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9.", "In the node-specific routing information of node 35, the node 31 is found as the subsequent node situated on the path for the given destination node 39.", "The parameter t acquires the value 2.", "Node 31 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9.", "In the node-specific routing information of node 31, the node 30 is found as the subsequent node situated on the path for the given destination node 39.", "The parameter t acquires the value 3.", "Node 30 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9.", "In the node-specific routing information of node 30, two subsequent nodes situated on different paths, namely node 33 and 34, are found for the given destination node 39 because four different paths are possible from the node 30 to the destination node 39: a first path via node;", "33 and 36, a second path via node 33, 34, 37 and 36, which two paths therefore yield the node 33 as the subsequent node, a third path via node 34, 37 and 36, and a fourth path via 34, 33 and 36, which two paths therefore yield the node 34 as the subsequent node.", "For both nodes, the parameter t acquires the value 4.", "Assuming that, of the nodes 33 and 34, the node 33 has the highest priority, the paths via this node are first assembled.", "In the node-specific routing information of node 33, two subsequent nodes situated on different paths, namely node 36 on the first path and node 34 on the second path, are found for the given destination node 39, and depending on the priority of said nodes 36 and 34, which dc not coincide with the destination node 39, both paths are further assembled in a particular order.", "For both nodes 36 and 34, the parameter t acquires the value 5.", "In the node-specific routing information of node 36, the node 39 is found as the subsequent node situated on the path for the given destination node 39.", "The parameter t acquires the value 6.", "Node 39 is the destination node 39 and the path from source node 32 to destination node 39 via the nodes 35, 31, 30, 33 and 36 and having length 6 has consequently been found.", "A routing loop does not exist in this first path.", "In the node-specific routing information of node 34, the node 37 is found as the subsequent node situated on the path for the given destination node 39.", "The parameter t acquires the value 6.", "Node 37 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9.", "In the node-specific routing information of node 37, the node 36 is found as the subsequent node situated on the path for the given destination node 39.", "The parameter t acquires the value 7.", "Node 36 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9.", "In the node-specific routing information of node 36, the node 39 is found as the subsequent node situated on the path for the given destination node 39.", "The parameter t acquires the value 8.", "Node 39 is the destination node 39 and the path from source node 32 to destination node 39 via the nodes 35, 31, 30, 33, 34, 37, 36 and 39 and having a length 8 has consequently been found.", "A routing loop does not exist in this second path.", "After the paths via node 33 have been assembled, the paths via node 34 are assembled.", "In the node-specific routing information of node 34 two subsequent nodes situated on different paths, namely node 37 on the third path and node 33 on the fourth path, are found with the given destination node 39, and depending on the priority of said nodes 37 and 33, which do not coincide with the destination node 39, both paths are assembled further in a particular order.", "For both nodes 37 and 33, the parameter t acquires the value 5.", "In the node-specific routing information of node 37, the node 36 is found as the subsequent node situated on the path for the given destination node.", "The parameter t acquires the value 6.", "Node 36 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9.", "In the node-specific routing information of node 36, the node 39 is found as the subsequent node situated on the path for the given destination node.", "The parameter t acquires the value 7.", "Node 39 is the destination node 39, and the path from source node 32 to destination node 39 via nodes 35, 31, 30, 34, 37 and 36 and having a length 7 has consequently been found.", "A routing loop does not exist in this third path.", "In the node-specific routing information of node 33, two subsequent nodes situated on different paths, namely nodes 36 and 30, are found for the given destination node 39, and depending on the priority of said nodes 36 and 30, which do not coincide with the destination node 39, both paths are assembled further in a particular order.", "For both nodes 36 and 30, the parameter t acquires the value 6.", "The fourth path therefore appears to contain different paths which have been split up.", "In the node-specific routing information of node 36, the node 39 is found as the subsequent node situated on the path for the given destination node 39.", "The parameter t acquires the value 7.", "Node 39 is the destination node 39, and the path from source node 32 to destination node 39 via nodes 35, 31, 30, 34, 33 and 36 and having a length 7 has consequently been found.", "A routing loop does not exist in this splitting-up of the fourth path.", "In the node-specific routing information of node 30, the node 34 is found as the subsequent node situated on the path for the given destination node 39.", "The parameter t acquires the value 7.", "Node 34 does not coincide with the destination node 39 and the value of the parameter t is less than the predetermined value 9.", "In the node-specific routing information of node 34, two subsequent nodes situated on different paths, namely node 37 and 33, are found as before, for the given destination node 39, and depending on the priority of said nodes 37 and 33, which do not coincide with the destination node 39, both paths are assembled further in a particular order.", "For both nodes 37 and 33, the parameter t acquires the value 8.", "From whichever of the paths 37 and 33 a path is now assembled further (and how a path, if any, is assembled from node 33) is irrelevant: before the destination node 39 is reached, the parameter t acquires the value 9, which indicates the existence of a routing loop in the partly assembled path.", "This loop comprises the nodes 30, 34, 33, 30, 34 etc.", "and could be eliminated in a simple manner either by eliminating the unidirectional routing possibility from node 30 to 34 and, as a consequence thereof, the unidirectional routing possibility from node 33 to 34 and from node 34 To node 33, in which case the routing possibilities in the opposite direction between the four nodes mentioned last should continue to exist, or by eliminating only the unidirectional routing possibility from node 33 to 30, in which case the routing possibility in the opposite direction between the nodes mentioned last should continue to exist.", "The detection means 21 shown in FIG. 4 comprise path assembly means 22 for assembling a path from a source node, on the one hand, to a destination node, on the other hand, on the basis of the node-specific routing information associated with the source node and the node-specific routing information associated with the nodes situated on the path.", "Path assembly means 22 are coupled to memory means 23 in which the node-specific routing information is stored, and they are coupled to counting means 24 for increasing a counter position by one counter unit at each subsequent node situated on a path during the assembly of said path.", "For this purpose, counting means 24 receive, from path assembly means 22, a counting pulse at a first input and a counter position, to be loaded and associated with a particular node, at a second input.", "An output of the counting means 24 is coupled to a first input of comparator means 25 for comparing the counter position associated with a partly assembled path with a predetermined counter value and for generating an alarm system in the event of it being exceeded, the predetermined counter value x being stored in memory means 26, which are coupled to a second input of comparator means 25.", "An output of comparator means 25 is coupled to path assembly means 22 for supplying the alarm signal.", "Path assembly means 22 are furthermore coupled to selection means 27 for successively selecting all the nodes as the destination node and for successively selecting all the remaining nodes as the source nodes for each destination node selected, and to ignoring means 28 for ignoring at least one of the two routing possibilities in the assembly of a path in the case of two nodes which are situated on the path to be assembled and which each have a direct routing possibility to the other in their routing information.", "In this connection, memory means 23 reproduce the memories of all the nodes symbolically if a routing loop is to be detected by actually assembling the path.", "If a routing loop is to be detected by assembling paths in a simulated manner, memory means 23 could also be formed by a central memory in which the node-specific routing information of all the nodes is stored." ]
RELATED APPLICATIONS [0001] This application claims the benefit of Korean Patent Application No. 10-2012-0133609, filed on Nov. 23, 2012, which is hereby incorporated by reference as if fully set forth herein. FIELD OF THE INVENTION [0002] The present invention relates to a navigation system, and, more specifically, to a device and method for actively generating intersection guidance information for turning using geometry information of a map. BACKGROUND OF THE INVENTION [0003] The related art includes the Korean Laid-Open Patent Publication No. 10-2008-0104548, entitled “Method for guiding intersection using point of interest and navigation system thereof.” The above related art makes use of POI (Point of Interest) information to improve turning guidance information using surrounding POI information of an intersection. [0004] FIG. 1 illustrates a block diagram of a navigation system for intersection guidance in the related art. Referring to FIG. 1 , the navigation system includes a route calculation unit 20 , a storage 30 , a user interface unit 40 , a display unit 50 , a voice output unit 60 , and a controller 70 . [0005] The storage 30 includes map data for the whole country and a map database that constructs route guidance data associated with the map data. In this case, intersection guidance information may be generated using values that have been investigated and fixed previously. That is, when there is an intersection on the map data, the navigation system displays an arrow, for example, in an intersection area indicating a turning direction. However, the intersection guidance navigation system has a problem in that the system can not actively generate the intersection guidance information and merely provided the guidance information stored previously as it. SUMMARY OF THE INVENTION [0006] In view of the above, the present invention provides a device and method for actively generating intersection guidance information that is needed for a client to turn in real time by analyzing geometry data (e.g., area information of building, more specifically, polygon data, etc) on a map while providing route navigation services. [0007] Further, the present invention provides a device and method for generating intersection guidance information, capable of storing and managing data smaller than those in the related art, by actively generating the intersection guidance information while providing a route navigation service, instead of using guidance information for intersections stored previously. [0008] Further, the present invention provides a device and method for generating intersection guidance information based on changed environment information around the intersections so that the intersection guidance information is adaptively generated while providing the route navigation services. [0009] In accordance with an aspect of the present invention, there is provided a device for generating intersection guidance information, which includes: a route setting unit configured to receive a route up to a destination; a candidate area detecting unit configured to search for a turning point on the searched route, and detect a surrounding area of the searched turning point as a candidate area; a candidate POI (point of interest) area detecting unit configured to detect a POI area as a candidate POI area, at least a portion of the POI area being included in the candidate area; a guidance POI area selecting unit configured to calculate distance between the candidate POI area and the turning point, search a candidate POI area whose distance calculated is shortest, and select the searched candidate POI area as a guidance POI area; and guidance information generating unit configured to generate guidance information for an intersection including the guidance POI area. [0010] In the exemplary embodiment, wherein the guidance information further comprises at least one of a distance from a current position to the intersection, and turning direction information at the intersection. [0011] In the exemplary embodiment, wherein the candidate area detecting unit sets the searched turning point, and a first point and a second point that are set apart from the searched turning point at a predetermined distance, and detects as a candidate area an internal area of an arbitrary closed curve that passes through all of the turning point, and the first and second points. [0012] In the exemplary embodiment, wherein the turning direction information comprises at least one of a left turn, a right turn, a U-turn, a P-turn and a rotary turn. [0013] In the exemplary embodiment, wherein the guidance POI area selecting unit calculates distance between the candidate POI area and the turning point, and selects as a guidance POI area a candidate POI area whose distance calculated is shortest. [0014] In the exemplary embodiment, wherein the guidance POI area selecting unit selects the guidance POI area in consideration of at least one of a client's position, a client's moving direction and a final destination. [0015] In the exemplary embodiment, wherein the route setting unit receives a route that is searched from an external device or a route that is searched internally and sets the searched route as input data to generate guidance information. [0016] In the exemplary embodiment, wherein when the candidate POI area detecting unit did not detect the candidate POI area, the candidate area detecting unit sets a third point and a fourth point that are apart from the turning point at a distance determined previously, the third and fourth points being different from the first point or the second point, and detects as a candidate area an internal area of an arbitrary closed curve that passes through all of the turning point, the third point, and the fourth point. [0017] In accordance with an embodiment of the present invention, there is provided a method for generating intersection guidance information performed by a server, which includes: searching a route up to a destination; searching for a turning point on the route to detect as a candidate area a surrounding area of the searched turning point; detecting a POI (Point Of Interest) area as a candidate POI area, at least a portion of the POI area being included in the candidate area; calculating distance between the candidate POI area and the turning point, searching for a candidate POI area whose distance calculated is shortest, and selecting the searched candidate POI area as a guidance POI area; and generating guidance information for a intersection including the guidance POI area. [0018] In the exemplary embodiment, wherein the guidance information further comprises at least one of a distance from a current position to the intersection, and turning direction information at the intersection. [0019] In the exemplary embodiment, wherein said detecting a surrounding area of the searched turning point as a candidate area comprises: setting the searched turning point and a first point and a second point that are set apart from the searched turning point at a predetermined distance; and detecting as a candidate area an internal area of an arbitrary closed curve that passes through all of the turning point, and the first and second points. [0020] In the exemplary embodiment, wherein the turning direction information comprises at least one of a left turn, a right turn, a U-turn, a P-turn and a rotary turn. [0021] In the exemplary embodiment, wherein said selecting the searched candidate POI area as a guidance POI area comprises: calculating distance between the candidate POI area and the turning point, and selecting as a guidance POI area a candidate POI area whose distance calculated is shortest. [0022] In the exemplary embodiment, the method further comprising: when not detecting a candidate POI area in said detecting the candidate POI area, determining whether to detect a candidate POI area in order to detect the candidate area, wherein said detecting the candidate POI area comprises detecting another candidate area different from the candidate area detected previously. [0023] In the exemplary embodiment, wherein said selecting the searched candidate POI area as a guidance POI area comprises: selecting a guidance POI area in consideration of at least one of a client's position, a client's moving direction and a final destination. [0024] As set for the above, the present invention may provide a device and method for generating intersection guidance information that is needed for a client to turn in real time by analyzing geometry data on a map while providing route navigation services. [0025] Further, the present invention may provide a device and method for generating intersection guidance information, capable of storing and managing data smaller than those in the art, by generating the intersection guidance information while providing a route navigation service, without using guidance information for intersections stored previously. [0026] In addition, the present invention may provide a device and method for generating intersection guidance information based on changed environment information around the intersections since the guidance information of intersections is generated while providing the route navigation services. BRIEF DESCRIPTION OF THE DRAWINGS [0027] The above and other objects and features of the present invention will become apparent from the following description of embodiments given in conjunction with the accompanying drawings, in which: [0028] FIG. 1 illustrates a block diagram of a navigation system for an intersection guidance in the related art; [0029] FIG. 2 illustrates a block diagram of a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention; [0030] FIG. 3 is a flowchart illustrating a method for generating intersection guidance information in accordance with an exemplary embodiment of the present invention; [0031] FIG. 4 shows a searched route provided by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention; [0032] FIG. 5 shows a candidate area provided by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention; [0033] FIG. 6 shows candidate POI areas provided by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention; and [0034] FIG. 7 shows candidate areas detected by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS [0035] The advantages and features of exemplary embodiments of the present invention and methods of accomplishing them will be clearly understood from the following description of the embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to those embodiments and may be implemented in various forms. It should be noted that the embodiments are provided to make a full disclosure and also to allow those skilled in the art to know the full scope of the present invention. Meanwhile, it should be noted that the terminologies used herein is merely intended to describe the embodiments and do not limit the scope of the present invention. [0036] A device and method for generating intersection guidance information in accordance with an exemplary embodiment of the present invention relates to a device and method for generating guidance information utilizing POI information around intersections when generating information to guide turning points on intersections among links of searched route. Since current maps around intersections are used without using guidance information stored previously when providing route guidance services, it is possible to provide guidance information changed as buildings around intersections and situations are changed. [0037] FIG. 2 illustrates a block diagram of a device 100 for generating intersection guidance information in accordance with an exemplary embodiment of the present invention. [0038] The device 100 for generating intersection guidance information includes a route setting unit 110 , a candidate area detecting unit 120 , a candidate POI area detection area 130 , a guidance POI area selecting unit 140 , and a guidance information generating unit 150 . [0039] The route setting unit 110 receives a route up to an intended destination and sets it as input data to generate guidance information. The route may be transferred from external devices or may be generated inside the device. The external devices used to transfer searched route may be a navigation system, a smart phone and a PC. The results produced from the route navigation may be provided as illustrated in FIG. 4 together with a map. [0040] The candidate area detecting unit 120 searches a turning point at an intersection on the searched route, and detects surroundings of the turning point as a candidate area. The detection of the candidate area is intended to generate intersection guidance information using POI areas, which are detected by the candidate POI area detecting unit 130 based on geometry data on a map, within the detected candidate area. The detected candidate area may be an area shaped in a triangle whose one apex becomes the turning point and whose two segments becomes both routes connected to the turning point. Further, the detected candidate area may be an internal area of an arbitrary closed curve (for example, a triangle, a circle, an ellipse, a lozenge, a tetragon, etc) which passes through both of two points that are apart from the turning point at a predetermined distance. [0041] When the candidate POI area is not detected through the candidate POI area detecting unit 130 , the candidate area may be newly set by differently setting the two points that are apart from the turning point at a predetermined distance. [0042] The candidate POI area detecting unit 130 detects one or more POI areas within a candidate area. The candidate POI area detecting unit 130 detects one or more POI areas that contained in the boundary of the candidate area or partially overlaps the candidate area, among the POI areas within the candidate area. The detected candidate POI area may be plural. When at least two POIs are detected, one POI area may be selected in consideration of a client's current position (e.g., driver's current position). The candidate POI area detecting unit 130 may detect candidate POI areas 610 to 640 as illustrated in FIG. 6 . When the candidate POI areas are not detected at all, it may be performed to detect candidate area again. [0043] The guidance POI area selecting unit 140 selects a guidance POI area used to generate intersection guidance information. The guidance POI area selecting unit 140 selects as a guidance POI area a POI area nearest to a turning point among the candidate POI area detected by the candidate POI area detecting unit 130 . The POI information of the guidance POI area selected by the guidance POI area selecting unit 140 is used to generate intersection guidance information. [0044] When at least two POI areas are selected by the guidance POI area selecting unit 140 , one POI area may be selected as a guidance POI area in consideration of a client's position, a moving direction and a final destination. [0045] The guidance information generating unit 150 generates guidance information using POI information of the guidance POI area. The guidance information may include guidance POI area information and turning direction information, for example, such as ‘turn right centering around a guidance POI area at a guidance POI area 100 m ahead’. The turning direction information may be a right turn, a left turn, a P-turn, a U-turn, a rotary turn, etc. The guidance information generated may be guided in a voice message or a text message. [0046] FIG. 3 is a flowchart illustrating a method for generating intersection guidance information in accordance with an exemplary embodiment of the present invention. [0047] The method for generating intersection guidance information may include steps of searching routes (Block S 320 ), detecting a candidate area (Block S 330 ), detecting a candidate POI area (Block S 340 ), determining whether to detect a candidate POI area (Block S 350 ), selecting a guidance POI area (Block S 360 ), and generating guidance information (Block S 370 ). [0048] At the step of searching routes (Block S 320 ), a server or local device searches routes up to a destination. The searched route is provided as illustrated in FIGS. 4 and 7 together with a map. [0049] The step of detecting a candidate area (Block S 330 ) includes detecting a candidate area including a POI area from a map before detecting POI area information that can be used to generate guidance information. The candidate area refers to a surrounding area of a turning point, which may be a triangle area of which an apex is the turning point and whose two segments are routes connected to the turning point. Alternatively, the candidate area may be an internal area of an arbitrary closed curve that passes through all of arbitrary two points that are apart from the turning point at predetermined distances and a turning point. [0050] As illustrated in FIG. 5 , reference numerals 500 and 510 may be candidate areas with respect to each turning point. [0051] The step of detecting a candidate POI area (Block S 340 ) includes detecting a candidate POI area that overlaps the candidate or is a space within the candidate area. The candidate POI area may be a space that is wholly included in the candidate area or whose portion is included in the candidate area. The step of detecting the candidate POI area (Block S 340 ) includes detecting a candidate POI area as illustrated in FIG. 6 . The number of the detected candidate POI areas may be 0 or more. [0052] The step of determining whether to detect the candidate POI area (Block S 350 ) includes determining whether the candidate POI area was detected. At the step of determining whether to detect the candidate POI area (Block S 350 ), when the number of the candidate POI area is zero, the step proceeds to the step of detecting a candidate area (Block S 330 ) where a candidate area may be detected again. In this case, it may be is possible to set as a candidate area another area that is not overlapped with an internal area of the closed curve mentioned above. [0053] The step of selecting the guidance POI area (Block S 360 ) includes selecting a guidance POI area used to generate intersection guidance information. The step of selecting a guidance POI area (Block S 360 ) includes selecting as a guidance POI area a candidate POI area that is nearest to the turning point among the candidate POI areas. The step of selecting the guidance POI area (Block S 360 ) may include selecting the guidance POI area using distance between the candidate POI area and the turning point. The step of selecting the guidance POI area (Block S 360 ) may include selecting the guidance POI area using distance between each apex or center and the turning point. [0054] The step of selecting the guidance POI area (Block S 360 ) may include selecting as the guidance POI area one POI area in consideration of a client's position, a moving direction and a final destination when at least two POI areas are selected. [0055] The step of generating the guidance information (Block S 370 ) includes generating guidance information using POI information of the POI area and turning direction information at an intersection. The turning direction information of the guidance POI area may include a right turn, a left turn, a rotary turn, a P-turn, and a U-turn. [0056] The intersection guidance information generated by the device and method for generating guidance information in accordance with an exemplary embodiment of the present invention may be utilized in a navigation system, a smart phone, an Internet path finding Website, and the like. The intersection guidance information may be provided in a voice message or text message. [0057] FIGS. 4 to 6 illustrate searched routes, candidate areas and candidate POI areas provided by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention. [0058] Referring to FIG. 4 , the searched route 400 may be illustrated together with a map. As a result of analyzing the searched route as illustrated, a turning point-1 410 and a turning point-2 420 are searched for. [0059] Referring to FIG. 5 , two points that are apart from the detected turning point-1 410 at a predetermined distance are selected, and an internal area of an arbitrary closed curve that passes through both turning points-1 and -2 is detected as a candidate area. The distance between the turning points 1 and 2 may be an arbitrary positive number. [0060] Spaces that have a portion overlapped with the detected candidate area 500 are detected as candidate POI areas. Referring to FIG. 6 , two candidate POI areas 630 and 640 are detected. [0061] Distances between each of the candidate POI areas 630 and 640 and a turning point 410 are calculated. Distances between each apex or center of the candidate POI areas 630 and 640 and the turning point-1 410 may be calculated. [0062] FIG. 7 shows candidate areas detected by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention. Here, the arrow indicates a route, and the route includes a turning point 700 . The device and method for generating intersection guidance information in accordance with the present invention detects a candidate area again when a candidate POI area is not detected. In this case, as illustrated in FIG. 7 , the candidate area may be detected in the order of 710 , 720 , 730 and 740 . Further, the candidate area may be detected in the order of 710 , 740 , 730 , and 720 . There is no limitation in the order of candidate area detection. The shape of the candidate area is not limited to a tetragon but may be an arbitrary closed curve (e.g., a circle, an ellipse, a triangle, a lozenge, a trapezoid, etc). [0063] The device and method for generating intersection guidance information in accordance with an exemplary embodiment of the present invention may be utilized in a map indicating an interior space as well as a common map. The POI area refers to a space divided logically according to usage in a map, which indicates an interior space, or a space divided into a shop, a bank, an office, etc. in a map indicating an exterior space. [0064] Further, in the device and method for generating intersection guidance information in accordance with an exemplary embodiment of the present invention, the guidance POI area is not limited to shops and stores positioned at 1st floor but may be selected as POI information of shops and stores positioned at 2nd floor or higher. [0065] While the invention has been shown and described with respect to the embodiments, the present invention is not limited thereto. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.
A device for generating intersection guidance information, which includes: a route setting unit configured to receive a route up to a destination; a candidate area detecting unit configured to search for a turning point on the searched route, and detect a surrounding area of the searched turning point as a candidate area; a candidate POI area detecting unit configured to detect a POI area as a candidate POI area, at least a portion of the POI area being included in the candidate area; a guidance POI area selecting unit configured to calculate distance between the candidate POI area and the turning point, search a candidate POI area whose distance calculated is shortest, and select the searched candidate POI area as a guidance POI area.
Analyze the document's illustrations and descriptions to summarize the main idea's core structure and function.
[ "RELATED APPLICATIONS [0001] This application claims the benefit of Korean Patent Application No. 10-2012-0133609, filed on Nov. 23, 2012, which is hereby incorporated by reference as if fully set forth herein.", "FIELD OF THE INVENTION [0002] The present invention relates to a navigation system, and, more specifically, to a device and method for actively generating intersection guidance information for turning using geometry information of a map.", "BACKGROUND OF THE INVENTION [0003] The related art includes the Korean Laid-Open Patent Publication No. 10-2008-0104548, entitled “Method for guiding intersection using point of interest and navigation system thereof.”", "The above related art makes use of POI (Point of Interest) information to improve turning guidance information using surrounding POI information of an intersection.", "[0004] FIG. 1 illustrates a block diagram of a navigation system for intersection guidance in the related art.", "Referring to FIG. 1 , the navigation system includes a route calculation unit 20 , a storage 30 , a user interface unit 40 , a display unit 50 , a voice output unit 60 , and a controller 70 .", "[0005] The storage 30 includes map data for the whole country and a map database that constructs route guidance data associated with the map data.", "In this case, intersection guidance information may be generated using values that have been investigated and fixed previously.", "That is, when there is an intersection on the map data, the navigation system displays an arrow, for example, in an intersection area indicating a turning direction.", "However, the intersection guidance navigation system has a problem in that the system can not actively generate the intersection guidance information and merely provided the guidance information stored previously as it.", "SUMMARY OF THE INVENTION [0006] In view of the above, the present invention provides a device and method for actively generating intersection guidance information that is needed for a client to turn in real time by analyzing geometry data (e.g., area information of building, more specifically, polygon data, etc) on a map while providing route navigation services.", "[0007] Further, the present invention provides a device and method for generating intersection guidance information, capable of storing and managing data smaller than those in the related art, by actively generating the intersection guidance information while providing a route navigation service, instead of using guidance information for intersections stored previously.", "[0008] Further, the present invention provides a device and method for generating intersection guidance information based on changed environment information around the intersections so that the intersection guidance information is adaptively generated while providing the route navigation services.", "[0009] In accordance with an aspect of the present invention, there is provided a device for generating intersection guidance information, which includes: a route setting unit configured to receive a route up to a destination;", "a candidate area detecting unit configured to search for a turning point on the searched route, and detect a surrounding area of the searched turning point as a candidate area;", "a candidate POI (point of interest) area detecting unit configured to detect a POI area as a candidate POI area, at least a portion of the POI area being included in the candidate area;", "a guidance POI area selecting unit configured to calculate distance between the candidate POI area and the turning point, search a candidate POI area whose distance calculated is shortest, and select the searched candidate POI area as a guidance POI area;", "and guidance information generating unit configured to generate guidance information for an intersection including the guidance POI area.", "[0010] In the exemplary embodiment, wherein the guidance information further comprises at least one of a distance from a current position to the intersection, and turning direction information at the intersection.", "[0011] In the exemplary embodiment, wherein the candidate area detecting unit sets the searched turning point, and a first point and a second point that are set apart from the searched turning point at a predetermined distance, and detects as a candidate area an internal area of an arbitrary closed curve that passes through all of the turning point, and the first and second points.", "[0012] In the exemplary embodiment, wherein the turning direction information comprises at least one of a left turn, a right turn, a U-turn, a P-turn and a rotary turn.", "[0013] In the exemplary embodiment, wherein the guidance POI area selecting unit calculates distance between the candidate POI area and the turning point, and selects as a guidance POI area a candidate POI area whose distance calculated is shortest.", "[0014] In the exemplary embodiment, wherein the guidance POI area selecting unit selects the guidance POI area in consideration of at least one of a client's position, a client's moving direction and a final destination.", "[0015] In the exemplary embodiment, wherein the route setting unit receives a route that is searched from an external device or a route that is searched internally and sets the searched route as input data to generate guidance information.", "[0016] In the exemplary embodiment, wherein when the candidate POI area detecting unit did not detect the candidate POI area, the candidate area detecting unit sets a third point and a fourth point that are apart from the turning point at a distance determined previously, the third and fourth points being different from the first point or the second point, and detects as a candidate area an internal area of an arbitrary closed curve that passes through all of the turning point, the third point, and the fourth point.", "[0017] In accordance with an embodiment of the present invention, there is provided a method for generating intersection guidance information performed by a server, which includes: searching a route up to a destination;", "searching for a turning point on the route to detect as a candidate area a surrounding area of the searched turning point;", "detecting a POI (Point Of Interest) area as a candidate POI area, at least a portion of the POI area being included in the candidate area;", "calculating distance between the candidate POI area and the turning point, searching for a candidate POI area whose distance calculated is shortest, and selecting the searched candidate POI area as a guidance POI area;", "and generating guidance information for a intersection including the guidance POI area.", "[0018] In the exemplary embodiment, wherein the guidance information further comprises at least one of a distance from a current position to the intersection, and turning direction information at the intersection.", "[0019] In the exemplary embodiment, wherein said detecting a surrounding area of the searched turning point as a candidate area comprises: setting the searched turning point and a first point and a second point that are set apart from the searched turning point at a predetermined distance;", "and detecting as a candidate area an internal area of an arbitrary closed curve that passes through all of the turning point, and the first and second points.", "[0020] In the exemplary embodiment, wherein the turning direction information comprises at least one of a left turn, a right turn, a U-turn, a P-turn and a rotary turn.", "[0021] In the exemplary embodiment, wherein said selecting the searched candidate POI area as a guidance POI area comprises: calculating distance between the candidate POI area and the turning point, and selecting as a guidance POI area a candidate POI area whose distance calculated is shortest.", "[0022] In the exemplary embodiment, the method further comprising: when not detecting a candidate POI area in said detecting the candidate POI area, determining whether to detect a candidate POI area in order to detect the candidate area, wherein said detecting the candidate POI area comprises detecting another candidate area different from the candidate area detected previously.", "[0023] In the exemplary embodiment, wherein said selecting the searched candidate POI area as a guidance POI area comprises: selecting a guidance POI area in consideration of at least one of a client's position, a client's moving direction and a final destination.", "[0024] As set for the above, the present invention may provide a device and method for generating intersection guidance information that is needed for a client to turn in real time by analyzing geometry data on a map while providing route navigation services.", "[0025] Further, the present invention may provide a device and method for generating intersection guidance information, capable of storing and managing data smaller than those in the art, by generating the intersection guidance information while providing a route navigation service, without using guidance information for intersections stored previously.", "[0026] In addition, the present invention may provide a device and method for generating intersection guidance information based on changed environment information around the intersections since the guidance information of intersections is generated while providing the route navigation services.", "BRIEF DESCRIPTION OF THE DRAWINGS [0027] The above and other objects and features of the present invention will become apparent from the following description of embodiments given in conjunction with the accompanying drawings, in which: [0028] FIG. 1 illustrates a block diagram of a navigation system for an intersection guidance in the related art;", "[0029] FIG. 2 illustrates a block diagram of a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention;", "[0030] FIG. 3 is a flowchart illustrating a method for generating intersection guidance information in accordance with an exemplary embodiment of the present invention;", "[0031] FIG. 4 shows a searched route provided by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention;", "[0032] FIG. 5 shows a candidate area provided by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention;", "[0033] FIG. 6 shows candidate POI areas provided by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention;", "and [0034] FIG. 7 shows candidate areas detected by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention.", "DETAILED DESCRIPTION OF THE EMBODIMENTS [0035] The advantages and features of exemplary embodiments of the present invention and methods of accomplishing them will be clearly understood from the following description of the embodiments taken in conjunction with the accompanying drawings.", "However, the present invention is not limited to those embodiments and may be implemented in various forms.", "It should be noted that the embodiments are provided to make a full disclosure and also to allow those skilled in the art to know the full scope of the present invention.", "Meanwhile, it should be noted that the terminologies used herein is merely intended to describe the embodiments and do not limit the scope of the present invention.", "[0036] A device and method for generating intersection guidance information in accordance with an exemplary embodiment of the present invention relates to a device and method for generating guidance information utilizing POI information around intersections when generating information to guide turning points on intersections among links of searched route.", "Since current maps around intersections are used without using guidance information stored previously when providing route guidance services, it is possible to provide guidance information changed as buildings around intersections and situations are changed.", "[0037] FIG. 2 illustrates a block diagram of a device 100 for generating intersection guidance information in accordance with an exemplary embodiment of the present invention.", "[0038] The device 100 for generating intersection guidance information includes a route setting unit 110 , a candidate area detecting unit 120 , a candidate POI area detection area 130 , a guidance POI area selecting unit 140 , and a guidance information generating unit 150 .", "[0039] The route setting unit 110 receives a route up to an intended destination and sets it as input data to generate guidance information.", "The route may be transferred from external devices or may be generated inside the device.", "The external devices used to transfer searched route may be a navigation system, a smart phone and a PC.", "The results produced from the route navigation may be provided as illustrated in FIG. 4 together with a map.", "[0040] The candidate area detecting unit 120 searches a turning point at an intersection on the searched route, and detects surroundings of the turning point as a candidate area.", "The detection of the candidate area is intended to generate intersection guidance information using POI areas, which are detected by the candidate POI area detecting unit 130 based on geometry data on a map, within the detected candidate area.", "The detected candidate area may be an area shaped in a triangle whose one apex becomes the turning point and whose two segments becomes both routes connected to the turning point.", "Further, the detected candidate area may be an internal area of an arbitrary closed curve (for example, a triangle, a circle, an ellipse, a lozenge, a tetragon, etc) which passes through both of two points that are apart from the turning point at a predetermined distance.", "[0041] When the candidate POI area is not detected through the candidate POI area detecting unit 130 , the candidate area may be newly set by differently setting the two points that are apart from the turning point at a predetermined distance.", "[0042] The candidate POI area detecting unit 130 detects one or more POI areas within a candidate area.", "The candidate POI area detecting unit 130 detects one or more POI areas that contained in the boundary of the candidate area or partially overlaps the candidate area, among the POI areas within the candidate area.", "The detected candidate POI area may be plural.", "When at least two POIs are detected, one POI area may be selected in consideration of a client's current position (e.g., driver's current position).", "The candidate POI area detecting unit 130 may detect candidate POI areas 610 to 640 as illustrated in FIG. 6 .", "When the candidate POI areas are not detected at all, it may be performed to detect candidate area again.", "[0043] The guidance POI area selecting unit 140 selects a guidance POI area used to generate intersection guidance information.", "The guidance POI area selecting unit 140 selects as a guidance POI area a POI area nearest to a turning point among the candidate POI area detected by the candidate POI area detecting unit 130 .", "The POI information of the guidance POI area selected by the guidance POI area selecting unit 140 is used to generate intersection guidance information.", "[0044] When at least two POI areas are selected by the guidance POI area selecting unit 140 , one POI area may be selected as a guidance POI area in consideration of a client's position, a moving direction and a final destination.", "[0045] The guidance information generating unit 150 generates guidance information using POI information of the guidance POI area.", "The guidance information may include guidance POI area information and turning direction information, for example, such as ‘turn right centering around a guidance POI area at a guidance POI area 100 m ahead’.", "The turning direction information may be a right turn, a left turn, a P-turn, a U-turn, a rotary turn, etc.", "The guidance information generated may be guided in a voice message or a text message.", "[0046] FIG. 3 is a flowchart illustrating a method for generating intersection guidance information in accordance with an exemplary embodiment of the present invention.", "[0047] The method for generating intersection guidance information may include steps of searching routes (Block S 320 ), detecting a candidate area (Block S 330 ), detecting a candidate POI area (Block S 340 ), determining whether to detect a candidate POI area (Block S 350 ), selecting a guidance POI area (Block S 360 ), and generating guidance information (Block S 370 ).", "[0048] At the step of searching routes (Block S 320 ), a server or local device searches routes up to a destination.", "The searched route is provided as illustrated in FIGS. 4 and 7 together with a map.", "[0049] The step of detecting a candidate area (Block S 330 ) includes detecting a candidate area including a POI area from a map before detecting POI area information that can be used to generate guidance information.", "The candidate area refers to a surrounding area of a turning point, which may be a triangle area of which an apex is the turning point and whose two segments are routes connected to the turning point.", "Alternatively, the candidate area may be an internal area of an arbitrary closed curve that passes through all of arbitrary two points that are apart from the turning point at predetermined distances and a turning point.", "[0050] As illustrated in FIG. 5 , reference numerals 500 and 510 may be candidate areas with respect to each turning point.", "[0051] The step of detecting a candidate POI area (Block S 340 ) includes detecting a candidate POI area that overlaps the candidate or is a space within the candidate area.", "The candidate POI area may be a space that is wholly included in the candidate area or whose portion is included in the candidate area.", "The step of detecting the candidate POI area (Block S 340 ) includes detecting a candidate POI area as illustrated in FIG. 6 .", "The number of the detected candidate POI areas may be 0 or more.", "[0052] The step of determining whether to detect the candidate POI area (Block S 350 ) includes determining whether the candidate POI area was detected.", "At the step of determining whether to detect the candidate POI area (Block S 350 ), when the number of the candidate POI area is zero, the step proceeds to the step of detecting a candidate area (Block S 330 ) where a candidate area may be detected again.", "In this case, it may be is possible to set as a candidate area another area that is not overlapped with an internal area of the closed curve mentioned above.", "[0053] The step of selecting the guidance POI area (Block S 360 ) includes selecting a guidance POI area used to generate intersection guidance information.", "The step of selecting a guidance POI area (Block S 360 ) includes selecting as a guidance POI area a candidate POI area that is nearest to the turning point among the candidate POI areas.", "The step of selecting the guidance POI area (Block S 360 ) may include selecting the guidance POI area using distance between the candidate POI area and the turning point.", "The step of selecting the guidance POI area (Block S 360 ) may include selecting the guidance POI area using distance between each apex or center and the turning point.", "[0054] The step of selecting the guidance POI area (Block S 360 ) may include selecting as the guidance POI area one POI area in consideration of a client's position, a moving direction and a final destination when at least two POI areas are selected.", "[0055] The step of generating the guidance information (Block S 370 ) includes generating guidance information using POI information of the POI area and turning direction information at an intersection.", "The turning direction information of the guidance POI area may include a right turn, a left turn, a rotary turn, a P-turn, and a U-turn.", "[0056] The intersection guidance information generated by the device and method for generating guidance information in accordance with an exemplary embodiment of the present invention may be utilized in a navigation system, a smart phone, an Internet path finding Website, and the like.", "The intersection guidance information may be provided in a voice message or text message.", "[0057] FIGS. 4 to 6 illustrate searched routes, candidate areas and candidate POI areas provided by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention.", "[0058] Referring to FIG. 4 , the searched route 400 may be illustrated together with a map.", "As a result of analyzing the searched route as illustrated, a turning point-1 410 and a turning point-2 420 are searched for.", "[0059] Referring to FIG. 5 , two points that are apart from the detected turning point-1 410 at a predetermined distance are selected, and an internal area of an arbitrary closed curve that passes through both turning points-1 and -2 is detected as a candidate area.", "The distance between the turning points 1 and 2 may be an arbitrary positive number.", "[0060] Spaces that have a portion overlapped with the detected candidate area 500 are detected as candidate POI areas.", "Referring to FIG. 6 , two candidate POI areas 630 and 640 are detected.", "[0061] Distances between each of the candidate POI areas 630 and 640 and a turning point 410 are calculated.", "Distances between each apex or center of the candidate POI areas 630 and 640 and the turning point-1 410 may be calculated.", "[0062] FIG. 7 shows candidate areas detected by a device for generating intersection guidance information in accordance with an exemplary embodiment of the present invention.", "Here, the arrow indicates a route, and the route includes a turning point 700 .", "The device and method for generating intersection guidance information in accordance with the present invention detects a candidate area again when a candidate POI area is not detected.", "In this case, as illustrated in FIG. 7 , the candidate area may be detected in the order of 710 , 720 , 730 and 740 .", "Further, the candidate area may be detected in the order of 710 , 740 , 730 , and 720 .", "There is no limitation in the order of candidate area detection.", "The shape of the candidate area is not limited to a tetragon but may be an arbitrary closed curve (e.g., a circle, an ellipse, a triangle, a lozenge, a trapezoid, etc).", "[0063] The device and method for generating intersection guidance information in accordance with an exemplary embodiment of the present invention may be utilized in a map indicating an interior space as well as a common map.", "The POI area refers to a space divided logically according to usage in a map, which indicates an interior space, or a space divided into a shop, a bank, an office, etc.", "in a map indicating an exterior space.", "[0064] Further, in the device and method for generating intersection guidance information in accordance with an exemplary embodiment of the present invention, the guidance POI area is not limited to shops and stores positioned at 1st floor but may be selected as POI information of shops and stores positioned at 2nd floor or higher.", "[0065] While the invention has been shown and described with respect to the embodiments, the present invention is not limited thereto.", "It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims." ]
FIELD OF THE INVENTION The present invention relates to a wireless communication system and wireless communication device that transmits and receives known signals such as pilot signals. The wireless communication system and wireless communication device suppresses the peak to average power ratio. BACKGROUND OF THE INVENTION Recent wireless communication systems have been utilizing code division multiplexing (CDM) and orthogonal frequency division multiplexing (OFDM). For example, FIG. 12 shows an outline of a wireless communication system arranged with multiple base stations BS 1 , BS 2 connected to a network (the network not pictured in the drawing) and a mobile station MS. The mobile station MS communicates with the base stations BS 1 , BS 2 with a good reception condition depending upon the mobile station MS position. A CDM system is a multiplex system which spreads a frequency utilizing different spreading codes. CDM systems tend to suffer from a problem in that if the number of the spreading codes increases the peak power becomes larger than the average power. An OFDM system is a transmission system which transmits on multiple sub-carriers related with respect to orthogonal frequency position. OFDM systems tend to suffer from a problem in that if the sub-carrier's phase timing overlap the peak power becomes larger than the average power. The base stations BS 1 , BS 2 and mobile station MS have a composition that includes a reception processing unit that demodulates and decodes signals received by an antenna and a transmission processing unit that transmits encoded and modulated signals from an antenna, and the transmission processing unit has a transmission amplifier that amplifies signals of wireless frequency. This transmission amplifier has an amplification characteristic which includes linear and non-linear characteristics. If an input signal amplitude is large, the transmission amplifier amplifies the input signal in a non-linear characteristic area therefore, the amplified output signal of the amplifier includes distortion. Proposals to deal with such problems have been shown by Japanese laid open application 2000-106548 which is known prior art in CDM systems. Moreover, Japanese laid open application H11-205276 is known prior art in OFDM systems of multiple sub-carriers. Regarding the CDM and OFDM systems, if the transmission amplifier is built so as to amplify up to the peak power without distortion, there will be a problem of increasing cost of the amplifier. Possible solutions to the above problems include the idea to suppress the peak and improve the peak to average power ratio (PAPR) by applying a system that provides a dummy code for peak suppression as in the above-described conventional CDM system, or a system that provides a subcarrier for peak suppression as in the OFDM system. However because a dummy code or non-information signal for PAPR suppression has a problem that the data information transmission efficiency is decreased. SUMMARY OF THE INVENTION The present invention, addresses the above previous problems controls the PAPR by making use of known signals or a channel that transmits known signals. The present invention includes a wireless communication system having a multiplex unit and a transmitter. The multiplex unit multiplexes a signal by combining a processed signal with a data signal. The transmitter transmits the multiplexed signal The processed signal includes a known signal which is processed to suppress a peak power to an average power ratio. The present invention further includes a wireless communication system having a reverse spread unit and a calculator. A reverse spread unit receives a transmitted signal which includes a known signal and a processed signal that shares a time domain a first known signal and a second known signal for suppressing a peak power to an average power ratio. The calculator calculates to compensate the second known signal in accordance with the first known signal. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of the main parts of a first working example of this invention. FIG. 2 is an explanatory diagram of first and second pilot signals on the transmission side. FIG. 3 is an explanatory diagram of first and second pilot signals on the receiver side. FIGS. 4( a ) and 4 ( b ) are explanatory diagrams of the phase change of the pilot signal. FIG. 5 is an explanatory diagram of the main parts of the reception unit of a wireless communication device. FIG. 6 is an explanatory diagram of the main parts of the reception unit of a wireless communication device. FIG. 7 is an explanatory diagram of the pattern of the first and second pilot signals. FIGS. 8(A) and 8(B) are explanatory diagrams of the pattern of the first and second pilot signals. FIGS. 9(A) and 9(B) are explanatory diagrams of the pattern of the first and second pilot signals. FIG. 10 is an explanatory diagram of the pattern of the first and second pilot signals. FIGS. 11(A) and 11(B) are explanatory diagrams of the effects of a simulation. FIG. 12 is a schematic explanatory diagram of a wireless communication system useful in explaining the present invention. DETAILED DESCRIPTION The wireless communication system of this invention has, in a wireless communication system that performs wireless communication using multiplexed signals that include data and known signals, a transmission unit that transmits together on the time axis the known signals and signals processed for suppressing the peak to average power ratio. If the known signals are transmitted on at least a certain frequency, then the transmission unit transmits, without temporal overlap, known signals to be transmitted on the certain frequency and signals processed so as to be able to suppress the peak to average power ratio to be transmitted on the certain frequency. If the known signals undergo spread processing using at least a certain spread code and are transmitted, then the transmission unit transmits, without temporal overlap, known signals to be spread by the certain spread code and transmitted, and signals processed so as to be able to suppress the peak to average power ratio to be spread by the certain spread code and transmitted. In a wireless communication system that performs wireless communication using multiplexed signals that include data and known signals, a transmission-side device divides the known signals into a first known signal and a second known signal, rotates the known signals to a phase that allows the peak to average power ratio to be suppressed and makes them into a second signal, and transmits together on the time axis the second signal and an unmodified first known signal, and a reception-side device that has a means that receives the first known signal and the second signal and, based on the first known signal, restores the second signal to the original known signal. Also a wireless communication device of this invention transmits and receives signals in which multiple data and known signals are multiplexed, divides the known signals into a first known signal and a second known signal, makes the known signals into a second signal by processing either the phase or the amplitude or both so as to be able to suppress the peak to average power ratio based on signals by which the multiple data are multiplexed, and transmits together on the time axis the second signal and an unmodified first known signal of the known signals. Also, it has a peak to average power ratio suppression signal calculation unit that processes and makes into the second signal either the phase or the amplitude, or both, of the known signals so as to be able to suppress the peak to average power ratio based on signals by which the multiple data are multiplexed, and a switching unit that inputs the known signals, with the unmodified first known signal, into the peak to average power ratio suppression signal calculation unit and controls the time period with the second signal. Also, it has a control means that controls the switching unit so as to adaptively vary the time period of the combination on the time axis of the first known signal of the known signals unmodified and the second signal by which the known signals are processed by the peak to average power ratio suppression signal calculation unit. Also, in a wireless communication device that has a channel that transmits known signals and that amplifies signals to be transmitted via the channel by an amplification unit in common with the transmission data of another channel and transmits them, it has in the channel via which the known signals are to be transmitted a control unit that controls so as to give them to the amplification unit after including signals that are not known signals. The wireless communication system of this invention has, in a wireless communication system that performs wireless communication using multiplexed signals that include data and pilot signals or other known signals, a means that transmits together on the time axis, each in its prescribed time period, pilot signals and other known signals and signals by which are processed the phase or amplitude or both so as to be able to suppress the peak to average power ratio. The wireless communication device of this invention has, in a wireless communication device that transmits and receives signals that multiplex multiple data and known signals, a means that divides the pilot signals and other known signals into a first known signal and a second known signal, processes phase or amplitude or both so as to be able to suppress the peak to average power ratio based on the signals that multiplex the known signals and multiple data, makes it into a second signal, combines on the time axis this second signal and the first known signal of the known signals unmodified, multiplexes them by multiplexing unit 3 , amplifies them by transmission amplification unit 2 , and transmits them from antenna 1 . FIG. 1 is an explanatory diagram of the main parts of the first working example of this invention. FIG. 1 may apply to the CDM system and shows the main parts of the transmission function of a wireless communication system or device. In the diagram, 1 is an antenna, 2 is a transmission amplification unit, 3 is a multiplexing unit, 4 is a PAPR (peak to average power ratio) suppression signal calculation unit, 5 - 1 to 5 -n and 6 are spread units, 7 is a composition unit, 8 is a switching unit, and 9 is a control unit. Transmission amplification unit 2 also up-converts signals multiplexed by multiplexing unit 3 to a transmission wireless frequency, a transmission amplifier for amplifying and transmitting from antenna 1 . The structure of spread units 5 - 1 to 5 -n is shown receiving a plurality of transmission data streams. The spread units 5 - 1 to 5 -n spread the plurality of data, Data # 1 to Data #n, in accordance with spread codes. The spread codes are respectively allocated data by data. Then, the spread output signals of the spread units 5 - 1 to 5 -n are multiplexed (combined) by composition unit 7 . Also shown in FIG. 1 is a pilot signal “Pilot” received by the switching unit 8 . In this example the pilot signal “Pilot” may be considered to be a known signal. Switching unit 8 switches over the pilot signal “Pilot” to either of the input into spread unit 6 directly (as is) or as an input into spread unit 6 via PAPR suppression signal calculation unit 4 . Switching unit 8 switches over the pilot signal in accordance with a signal from a control unit 9 . As shown in the FIG. 1 example the pilot signal “Pilot” from the switching unit 8 is input directly into spread unit 6 in this case is as P 1 the first known signal. The second signal P 2 to be input into spread unit 6 is output from PAPR suppression signal calculation unit 4 . The PAPR suppression signal calculation unit 4 has a composition for generating the second signal P 2 that is to suppress the peak power value by using a signal that undergoes multiplexing composition by composition unit 7 and the pilot signal Pilot. The output of the PAPR suppression signal calculation unit 4 is supplied to the spread unit 6 . The switching processing of switching unit 8 can be controlled by control unit 9 . For example, control unit 9 the switching to a predetermined switching pattern so as to select the direct input of the signal P 1 for a prescribed time period of the leading part of the slot or frame, and to the signal P 2 for other time periods, etc. In another example, control unit 9 may provide control for peak suppression in accordance with calculation results yielded by PAPR suppression signal calculation unit 4 . For example the PAPR suppression signal calculation unit 4 may provide input to the control unit 9 . Therefore the multiplexed signals to be input into transmission amplification unit 2 and amplified are in a peak-suppressed state and it is possible to suppress the unneeded radiation component. Moreover, both P 1 and P 2 are processed by the same spread unit 6 therefore the spread code is applied the same code. In this case it should be noted that P 1 and P 2 are not transmitted by switching unit 8 with any temporal overlap. Also, in spread unit 6 , P 1 can be transmitted with multiple spread codes, but P 2 can be transmitted with one spread code among the multiple spread codes. Also, with regard to the frequency relationships as well, P 1 and P 2 are both transmitted on the same frequency. And although, P 1 can be transmitted with multiple frequencies, but P 2 can be transmitted with one frequency among the multiple frequencies. In the CDM system or the OFDM system, the processed pilot signal “pilot” which is a known pattern or signal is transmitted. For data reception processing, the receiver can correlate transmission paths because the receiver can obtain radio transmission path status information from the received and divided pilot signal. By using a known signal for example pilot signal this invention does not need a channel etc, to transmit a special signal for suppressing PAPR. The receiver divides the second signal P 2 from the received signal to use the first known signal, for example pilot signal etc. And also, the receiver corrects the phase and amplitude of the second signal P 2 so as to correct all pilot signal 1 is known signal, therefore the receiver is able to correct propagation path correction, etc. FIG. 2 is an explanatory diagram of an example of a first pilot signal P 1 and a second pilot signal P 2 as the known signals referred to above; Assuming the modulation system for the case in which a pilot signal is to be transmitted by QPSK modulation. If the known pilot signal is signal point (1,1), then conventionally a pilot signal is transmitted as this signal point (1,1) multiplexed together with the data, etc. But in this working example, a first pilot signal P 1 is transmitted in every prescribed time period for the pilot signal which is the known signal point (1,1). In order to make it possible for PAPR suppression to be done by PAPR suppression signal calculation unit 4 , after this first pilot signal P 1 is transmitted, one of the four signal points (1,1), (1,−1), (−1,1), (−1,−1) is selected and processed; that is, it is transmitted as second pilot signal P 2 in a phase-controlled state. Moreover, a single or plural of the first pilot signal P 1 is always transmitted every prescribed time period, and during this first pilot signal P 1 , second pilot signal P 2 is transmitted multiplexed onto the time axis (here too, without temporal overlap). The time interval for first pilot signal P 1 should be selected so as to allow the phase change due to the wireless propagation path during this period to be ignored to some extent. On the receiver side, the phase of second pilot signal P 2 can be corrected by taking the phase of first pilot signal P 1 as a reference, making possible restoration to pilot signals of a known phase relationship. Therefore correction processing can be done on the received data by a reception-side propagation path correction means using the pilot signal. In this way, PAPR suppression is done by transmitting a pilot signal in which a first pilot signal P 1 and a second signal P 2 are combined on the time axis (for example, combined without temporal overlap), and on the receiver side, as shown in FIG. 3 , this pilot signal is set so as to be able to ignore the phase change of the second signal P 2 received during the first pilot signal P 1 of known pattern, and because the second pilot signal P 2 is one of the four signal points (1,1), (1,−1), (−1,1), (−1,−1), processing can be done that returns it to known signal point (1,1) of the first pilot signal P 1 . Therefore processing as a pilot signal can be done in the same way as in the case in which an ordinary pilot signal undergoes reception processing. In the aforesaid case, the second signal P 2 , for which the first pilot signal P 1 is phase-rotated in 90-degree units so as to obtain a PAPR suppression effect in order to effect PAPR suppression, is set to a phase that corresponds to the calculation results in PAPR suppression signal calculation unit 4 , but the transmission can be done with this second signal P 2 phase-rotated in units of θ=360/n (where n is an integer greater than or equal to 2). For example, if we set n=2, then second signal P 2 can be transmitted selected from the calculation results in PAPR suppression signal calculation unit 4 from the two choices 0 degrees and 180 degrees, and if we set n=4, it can be selected from the four phase rotations referred to above. In this case, the higher the value n is set to, the greater the number of choices that can be selected, so the PAPR suppression effect can be improved. FIGS. 4( a ) and 4 ( b ) are explanatory diagrams of the phase change; in 4 ( a ), if the phase change is large as indicated by the dotted-line arrow, then if the selection phase θ of second signal P 2 is made small and the number of choices is made large, then on the receiver side the phase change in the wireless propagation path and the selection phase of second signal P 2 will come to approximate each other, and reception demodulation of second signal P 2 may be difficult. In that case, the selection phase θ of second signal P 2 is made large. That is, the n in θ=360/n is set to a small value. By this, reception demodulation of second signal P 2 becomes easier. And as shown in FIG. 4( b ), if the phase change is small as indicated by the dotted-line arrow, then even if the phase rotation θ is made small, that is, even if the n in the aforesaid θ=360/n is set to a large value, then reception demodulation of second pilot signal P 2 will be easy, and because the selection of phases can be made finer, the PAPR suppression effect can be improved. In FIG. 1 , amplitude control (amplitude control unit not pictured) can be provided that controls the amplitude of first pilot signal P 1 , second signal P 2 , or both, according to the calculation results given by PAPR suppression signal calculation unit 4 . For example, if the amplitude is to be controlled with respect to second signal P 2 , then on the receiver side the amplitude of second signal P 2 can be corrected based on the reception demodulation results of first pilot signal P 1 . Also, both the phase and amplitude of second signal P 2 can be controlled in correspondence with the calculation results given by PAPR suppression signal calculation unit 4 . For the amplitude of first pilot signal P 1 as well, PAPR suppression can be done by controlling it. In FIG. 5 , which shows the composition of the main parts of the reception unit of a wireless communication device to which the CDM system is applied, 11 is a pilot signal despread unit, 12 and 13 are switching units, 14 is a pilot signal compensation unit, 15 is a pilot signal compensation quantity calculation unit, 16 is a data despread unit, 17 is a propagation path correction unit, and 18 is a control unit. Omitted from the diagram are the makeup of the reception antenna, demodulation unit, and other high-frequency processing parts and the processing units for reception data, etc. By control unit 18 , switching operations are carried out in such a way that during the reception time period of first pilot signal P 1 , switching units 12 and 13 are set to the switching state shown in the diagram, and during the reception time period of second signal P 2 , switching unit 12 is connected between pilot signal despread unit 11 and pilot signal compensation unit 14 , and switching unit 13 is connected between pilot signal compensation unit 14 and propagation path correction unit 17 . If a pilot signal pattern that shows the transmission time periods of the first and second pilot signals P 1 and P 2 is preset, the switching control of switching units 12 and 13 by this control unit 18 follows this pattern, and if it changes adaptively, switching control can be done in correspondence with the transmission time periods of first and second pilot signals P 1 and P 2 by receiving control information that indicates the pilot signal pattern. Moreover, although there is no need to detect the reception time period of the first pilot signal, various methods can be applied. For example, a wireless communication device that transmits the first pilot signal can be detected by taking the signals of separate transmitting channels as distinguishing marks. For example, it can be arranged that the first pilot signal is transmitted from the time when a signal of a separate channel corresponds to a part that constitutes a specified signal pattern (the same timing as that part, or a time that is a prescribed time before or after that part), and by detection of the specified signal pattern on the receiver side, the start of the first pilot signal that is inserted periodically can be detected. Also, if it is set up so that the first pilot signal is transmitted multiply and continuously, then by receiving the same signal multiple times in a row, it can be detected that it is the first pilot signal, and that the continuous time period is the transmission time period of the first pilot signal. At that time, in consideration of the fact that the second pilot signal also will be the same signal continuously, the transmission time period of the first pilot signal can be detected by the fact that the continuous time period appears repeatedly multiple times with a known periodicity. And if the first pilot signal is transmitted periodically, then if it can be detected for multiple periods that the same signal can be received periodically, it will be possible to detect the transmission time period of the first pilot signal. The first pilot signal P 1 and the second signal P 2 undergo despread processing in pilot signal despread unit 11 according to the spread code assigned to the pilot signal, and by the switching state of switching units 12 and 13 that is pictured in the diagram, first pilot signal P 1 is input into pilot signal compensation quantity calculation unit 15 and propagation path correction unit 17 . And in the same way as in the case of an ordinary pilot signal, data that undergoes despread processing by data signal despread unit 16 is corrected in propagation path correction unit 17 and is transferred to a later-stage processing unit that is not pictured in the diagram. In the time period that corresponds to the transmission time period of second signal P 2 , switching units 12 and 13 are switched from the state pictured in the diagram, second signal P 2 is input into pilot signal compensation unit 14 , in pilot signal compensation quantity calculation unit 15 , compensation of the phase rotation, etc. corresponding to second signal P 2 is done based on the compensation quantity for the phase rotation, etc. corresponding to second signal P 2 for which the first pilot signal P 1 is taken as the reference, and it is input into propagation path correction unit 17 as a pilot signal of the same known pattern as the first pilot signal. Therefore by taking second signal P 2 as a pilot signal of the same known pattern as first pilot signal P 1 , correction of the propagation path properties can be done with respect to the data. FIG. 6 shows the configuration of the principal parts of the reception unit of a wireless communication device to which is applied a CDM system in which part of the configuration shown in FIG. 5 has been modified; the same symbols as in FIG. 5 denote the same named parts. Moreover, control unit 18 has been omitted from the diagram. Also, in the configuration shown in FIG. 5 , the case is shown in which first pilot signal P 1 is used and then compensation of second signal P 2 is done, but in FIG. 6 it has a configuration in which second signal P 2 compensated by pilot signal compensation unit 14 is also input into pilot signal compensation quantity calculation unit 15 , and compensation of second signal P 2 is done. FIG. 7 is an explanatory diagram for the transmission ratio of first pilot signal P 1 and second signal P 2 ; taking symbol M of first pilot signal P 1 and symbol N of second signal P 2 as pilot frames, these pilot frames can be transmitted repeatedly. As stated above, the length of the pilot frame in this case can also be set to a time period that is long enough so that the phase change in the transmission time period of second signal P 2 during first pilot signal P 1 can be ignored. Also, it is usual to set the ratio M/N of first pilot signal P 1 and second signal P 2 to a preset value, but this could also be varied based on the state of the wireless propagation path, etc. FIG. 8 (A) shows the case in which a pilot signal is used in which, within one pilot frame, first pilot signal P 1 - 1 is arranged as symbol M, then second signal P 2 is arranged as symbol N, then first pilot signal P 1 - 2 is arranged as symbol L; their ratio M/N/L can be set to a preset value. Also, as stated above, the interval between first pilot signals P 1 - 1 and P 1 - 2 can be set to a time period whereby the phase change can be ignored. In FIG. 8(B) , (a) and (b) are an explanatory diagram for the case in which there is an interval in which no pilot signal is transmitted; (a) shows the case in which the pilot signal pattern shown in FIG. 7 is used, and (b) shows the case in which the pilot signal pattern shown in FIG. 8 (A) are used. If the phase change in the interval during which no pilot signal is transmitted is large, in the case of the pilot signal pattern shown in (a), the end of the interval during which there is no transmission is second signal P 2 , and in the case of the pilot signal pattern shown in (b) it is first pilot signal P 1 - 2 , so the demodulation processing of second signal P 2 in the reception-side demodulation of the pilot signal has the advantage of having better demodulation precision than the case shown in (a). FIG. 9 (A) shows the case in which pilot signals are repeatedly transmitted in a pattern where the ratio between first pilot signal P 1 and second signal P 2 changes as M 1 :N 1 , M 2 :N 2 , M 3 :N 3 . If pilot signals are transmitted by a pattern in which the ratio is changed with each pilot frame in this way, it can be done by controlling switching unit 8 by control unit 9 in FIG. 1 . If such switching control is applied to, for example, a wireless communication system that performs synchronization using pilot signals, then by using a pilot frame in which first pilot signal P 1 has a high ratio, the receiver side can perform synchronization with greater precision than if a pilot frame of another ratio were used. FIG. 9(B) shows as Case 1 and Case 2 , the ratio of first pilot signal P 1 and second signal P 2 in the pilot frames is made different, and which of Case 1 and Case 2 to adopt can be changed adaptively. For example, when it is determined in PAPR suppression signal calculation unit 4 (see FIG. 1 ) that the PAPR is large, or when there are many spread codes in the CDM system, then Case 2 is selected, which includes many second signals P 2 for carrying out PAPR suppression, and when it is determined that the PAPR is small, or when there are few spread codes in the CDM system, then Case 1 is selected, which includes many first pilot signals P 1 , and in order to notify the receiver side of this pilot signal pattern, notice is given to the receiver side by control information, for example setting Case 1 =0, Case 2 =1 by a one-bit configuration. Moreover, if a selection is to be made from among a larger variety of pilot signal patterns by the two types Case 1 and Case 2 , the receiver side can be given notice of the pilot signal pattern by a number of bits that corresponds to the number of types. This amounts to, for example, doing switching control of switching units 12 and 13 by reception-side control unit 18 shown in FIG. 5 . FIG. 10 shows cases in which the pilot frame is not fixed but is variable; Case 1 and Case 2 depict the case in which the length of the pilot frame is the same and the ratio of first pilot signal P 1 and second signal P 2 is different, while Case 3 and Case 4 depict the case in which the length of the pilot frame is shorter than in Case 1 and Case 2 . The selection from among Case 1 to Case 4 can be made according to the following conditions. Case 1 : if it is anticipated that the phase change in the wireless propagation path is small and the PAPR is small; Case 2 : if it is anticipated that the phase change in the wireless propagation path is small and the PAPR is large; Case 3 : if it is anticipated that the phase change in the wireless propagation path is large and the PAPR is small; Case 4 : if it is anticipated that the phase change in the wireless propagation path is large and the PAPR is large. That is, if the phase change of the communication path that includes the wireless propagation path is large, the precision of the pilot demodulation signal on the receiver side can be improved by making the pilot frame smaller. If the pilot signal pattern is varied adaptively in this way, by notifying the receiver side of the control information, it is possible on the receiver side to do reception processing on the first and second pilot signals P 1 and P 2 and return the second signal P 2 to first pilot signal P 1 . FIG. 11 (A) shows the results of a simulation of the peak suppression effect, and FIG. 11(B) shows the results of a simulation of a conventional example and of this invention. FIG. 11 (A) shows the PAPR suppression effect if one applies high-speed downlink packet access (HSPDA) for speeding up the transmission rate of the downlink in the wideband-code division multiple access (W-CDMA) system; it shows the results of a computer simulation, given that the transmission signal is set to 24-code multiplex, the pilot channel for peak power suppression is set to a common pilot channel (CPICH), and the ratio of the CPICH power to the total transmission power is set to 0.1. The peak to average power ratio (PAPR) is plotted along the horizontal axis, and the cumulative probability is plotted along the vertical axis. “With peak suppression” in the diagram is the result if the ratio of the first pilot signal P 1 to second signal P 2 in this invention is set to 1:9. It is seen that there is a peak suppression effect of about 0.8 dB at a cumulative probability of 10 −4 . FIG. 11 (B), like in FIG. 11(A) , shows the results of a simulation if HSPDA is applied and the travel speed of the mobile wireless communication device is set to 3 km/h; Ior/Ioc (the ratio of own-cell power to multi-cell power on the receiver side) is plotted along the horizontal axis, and the throughput of the high-speed downlink shared channel (HS-DSCH) is plotted along the vertical axis. In this invention, because peak suppression is done using a pilot signal by CPICH, there is no need to set up a new channel for peak suppression as in a conventional example, so the HS-DSCH power can be allocated just for the portion of the channel for peak suppression of the conventional example. As a result, it is clear that in this invention the signal-to-interference ratio (SIR) of the HS-DSCH is greater, and the throughput is better, than in the conventional example. By changing from the PAPR suppression means of the conventional example to the PAPR suppression means of this invention, the rate of throughput increase becomes about 10% in the region where or/Ioc=15 dB or less. For the known signals referred to above, the explanation has dealt mainly with the case in which a pilot signal is used in the CDM system, but a pilot signal and other known signals in a multiplexing transmission system such as the OFDM system can be transmitted as a first known signal and a second signal that controls the phase or amplitude or both so as to perform PAPR suppression. Also, it is a concept of whether a channel is the same or different, but if the transmission frequency and spread code are the same, it can be deemed to be the same channel, even if the transmission times are different. That is, for example, in FIG. 1 , although the transmission part of P 1 and the transmission part of P 2 differ temporally, their transmission frequency and spread code are the same, and both P 1 and P 2 can be deemed to be being transmitted on the same channel (pilot channel). This invention provides advantages because it transmits together on the time axis known signals and signals that are processed with respect to the known signals so as to be able to suppress the peak to average power ratio. Also, it makes use of part of a channel that transmits known signals, with this invention it is unnecessary to newly introduce a special channel for peak suppression. There is no need to newly allocate for suppression purposes any frequency that is different from the channel that transmits known signals, or any different spread code.
A wireless communication system, to control a peak power to an average power ratio because an amplifier characteristic of the wireless communication system include non-linear characteristic if input signal large the amplifier makes distortions. A wireless communication system comprises for suppressing a peak power to an average power ratio to process known signal like a pilot signal.
Briefly outline the background technology and the problem the invention aims to solve.
[ "FIELD OF THE INVENTION The present invention relates to a wireless communication system and wireless communication device that transmits and receives known signals such as pilot signals.", "The wireless communication system and wireless communication device suppresses the peak to average power ratio.", "BACKGROUND OF THE INVENTION Recent wireless communication systems have been utilizing code division multiplexing (CDM) and orthogonal frequency division multiplexing (OFDM).", "For example, FIG. 12 shows an outline of a wireless communication system arranged with multiple base stations BS 1 , BS 2 connected to a network (the network not pictured in the drawing) and a mobile station MS.", "The mobile station MS communicates with the base stations BS 1 , BS 2 with a good reception condition depending upon the mobile station MS position.", "A CDM system is a multiplex system which spreads a frequency utilizing different spreading codes.", "CDM systems tend to suffer from a problem in that if the number of the spreading codes increases the peak power becomes larger than the average power.", "An OFDM system is a transmission system which transmits on multiple sub-carriers related with respect to orthogonal frequency position.", "OFDM systems tend to suffer from a problem in that if the sub-carrier's phase timing overlap the peak power becomes larger than the average power.", "The base stations BS 1 , BS 2 and mobile station MS have a composition that includes a reception processing unit that demodulates and decodes signals received by an antenna and a transmission processing unit that transmits encoded and modulated signals from an antenna, and the transmission processing unit has a transmission amplifier that amplifies signals of wireless frequency.", "This transmission amplifier has an amplification characteristic which includes linear and non-linear characteristics.", "If an input signal amplitude is large, the transmission amplifier amplifies the input signal in a non-linear characteristic area therefore, the amplified output signal of the amplifier includes distortion.", "Proposals to deal with such problems have been shown by Japanese laid open application 2000-106548 which is known prior art in CDM systems.", "Moreover, Japanese laid open application H11-205276 is known prior art in OFDM systems of multiple sub-carriers.", "Regarding the CDM and OFDM systems, if the transmission amplifier is built so as to amplify up to the peak power without distortion, there will be a problem of increasing cost of the amplifier.", "Possible solutions to the above problems include the idea to suppress the peak and improve the peak to average power ratio (PAPR) by applying a system that provides a dummy code for peak suppression as in the above-described conventional CDM system, or a system that provides a subcarrier for peak suppression as in the OFDM system.", "However because a dummy code or non-information signal for PAPR suppression has a problem that the data information transmission efficiency is decreased.", "SUMMARY OF THE INVENTION The present invention, addresses the above previous problems controls the PAPR by making use of known signals or a channel that transmits known signals.", "The present invention includes a wireless communication system having a multiplex unit and a transmitter.", "The multiplex unit multiplexes a signal by combining a processed signal with a data signal.", "The transmitter transmits the multiplexed signal The processed signal includes a known signal which is processed to suppress a peak power to an average power ratio.", "The present invention further includes a wireless communication system having a reverse spread unit and a calculator.", "A reverse spread unit receives a transmitted signal which includes a known signal and a processed signal that shares a time domain a first known signal and a second known signal for suppressing a peak power to an average power ratio.", "The calculator calculates to compensate the second known signal in accordance with the first known signal.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of the main parts of a first working example of this invention.", "FIG. 2 is an explanatory diagram of first and second pilot signals on the transmission side.", "FIG. 3 is an explanatory diagram of first and second pilot signals on the receiver side.", "FIGS. 4( a ) and 4 ( b ) are explanatory diagrams of the phase change of the pilot signal.", "FIG. 5 is an explanatory diagram of the main parts of the reception unit of a wireless communication device.", "FIG. 6 is an explanatory diagram of the main parts of the reception unit of a wireless communication device.", "FIG. 7 is an explanatory diagram of the pattern of the first and second pilot signals.", "FIGS. 8(A) and 8(B) are explanatory diagrams of the pattern of the first and second pilot signals.", "FIGS. 9(A) and 9(B) are explanatory diagrams of the pattern of the first and second pilot signals.", "FIG. 10 is an explanatory diagram of the pattern of the first and second pilot signals.", "FIGS. 11(A) and 11(B) are explanatory diagrams of the effects of a simulation.", "FIG. 12 is a schematic explanatory diagram of a wireless communication system useful in explaining the present invention.", "DETAILED DESCRIPTION The wireless communication system of this invention has, in a wireless communication system that performs wireless communication using multiplexed signals that include data and known signals, a transmission unit that transmits together on the time axis the known signals and signals processed for suppressing the peak to average power ratio.", "If the known signals are transmitted on at least a certain frequency, then the transmission unit transmits, without temporal overlap, known signals to be transmitted on the certain frequency and signals processed so as to be able to suppress the peak to average power ratio to be transmitted on the certain frequency.", "If the known signals undergo spread processing using at least a certain spread code and are transmitted, then the transmission unit transmits, without temporal overlap, known signals to be spread by the certain spread code and transmitted, and signals processed so as to be able to suppress the peak to average power ratio to be spread by the certain spread code and transmitted.", "In a wireless communication system that performs wireless communication using multiplexed signals that include data and known signals, a transmission-side device divides the known signals into a first known signal and a second known signal, rotates the known signals to a phase that allows the peak to average power ratio to be suppressed and makes them into a second signal, and transmits together on the time axis the second signal and an unmodified first known signal, and a reception-side device that has a means that receives the first known signal and the second signal and, based on the first known signal, restores the second signal to the original known signal.", "Also a wireless communication device of this invention transmits and receives signals in which multiple data and known signals are multiplexed, divides the known signals into a first known signal and a second known signal, makes the known signals into a second signal by processing either the phase or the amplitude or both so as to be able to suppress the peak to average power ratio based on signals by which the multiple data are multiplexed, and transmits together on the time axis the second signal and an unmodified first known signal of the known signals.", "Also, it has a peak to average power ratio suppression signal calculation unit that processes and makes into the second signal either the phase or the amplitude, or both, of the known signals so as to be able to suppress the peak to average power ratio based on signals by which the multiple data are multiplexed, and a switching unit that inputs the known signals, with the unmodified first known signal, into the peak to average power ratio suppression signal calculation unit and controls the time period with the second signal.", "Also, it has a control means that controls the switching unit so as to adaptively vary the time period of the combination on the time axis of the first known signal of the known signals unmodified and the second signal by which the known signals are processed by the peak to average power ratio suppression signal calculation unit.", "Also, in a wireless communication device that has a channel that transmits known signals and that amplifies signals to be transmitted via the channel by an amplification unit in common with the transmission data of another channel and transmits them, it has in the channel via which the known signals are to be transmitted a control unit that controls so as to give them to the amplification unit after including signals that are not known signals.", "The wireless communication system of this invention has, in a wireless communication system that performs wireless communication using multiplexed signals that include data and pilot signals or other known signals, a means that transmits together on the time axis, each in its prescribed time period, pilot signals and other known signals and signals by which are processed the phase or amplitude or both so as to be able to suppress the peak to average power ratio.", "The wireless communication device of this invention has, in a wireless communication device that transmits and receives signals that multiplex multiple data and known signals, a means that divides the pilot signals and other known signals into a first known signal and a second known signal, processes phase or amplitude or both so as to be able to suppress the peak to average power ratio based on the signals that multiplex the known signals and multiple data, makes it into a second signal, combines on the time axis this second signal and the first known signal of the known signals unmodified, multiplexes them by multiplexing unit 3 , amplifies them by transmission amplification unit 2 , and transmits them from antenna 1 .", "FIG. 1 is an explanatory diagram of the main parts of the first working example of this invention.", "FIG. 1 may apply to the CDM system and shows the main parts of the transmission function of a wireless communication system or device.", "In the diagram, 1 is an antenna, 2 is a transmission amplification unit, 3 is a multiplexing unit, 4 is a PAPR (peak to average power ratio) suppression signal calculation unit, 5 - 1 to 5 -n and 6 are spread units, 7 is a composition unit, 8 is a switching unit, and 9 is a control unit.", "Transmission amplification unit 2 also up-converts signals multiplexed by multiplexing unit 3 to a transmission wireless frequency, a transmission amplifier for amplifying and transmitting from antenna 1 .", "The structure of spread units 5 - 1 to 5 -n is shown receiving a plurality of transmission data streams.", "The spread units 5 - 1 to 5 -n spread the plurality of data, Data # 1 to Data #n, in accordance with spread codes.", "The spread codes are respectively allocated data by data.", "Then, the spread output signals of the spread units 5 - 1 to 5 -n are multiplexed (combined) by composition unit 7 .", "Also shown in FIG. 1 is a pilot signal “Pilot”", "received by the switching unit 8 .", "In this example the pilot signal “Pilot”", "may be considered to be a known signal.", "Switching unit 8 switches over the pilot signal “Pilot”", "to either of the input into spread unit 6 directly (as is) or as an input into spread unit 6 via PAPR suppression signal calculation unit 4 .", "Switching unit 8 switches over the pilot signal in accordance with a signal from a control unit 9 .", "As shown in the FIG. 1 example the pilot signal “Pilot”", "from the switching unit 8 is input directly into spread unit 6 in this case is as P 1 the first known signal.", "The second signal P 2 to be input into spread unit 6 is output from PAPR suppression signal calculation unit 4 .", "The PAPR suppression signal calculation unit 4 has a composition for generating the second signal P 2 that is to suppress the peak power value by using a signal that undergoes multiplexing composition by composition unit 7 and the pilot signal Pilot.", "The output of the PAPR suppression signal calculation unit 4 is supplied to the spread unit 6 .", "The switching processing of switching unit 8 can be controlled by control unit 9 .", "For example, control unit 9 the switching to a predetermined switching pattern so as to select the direct input of the signal P 1 for a prescribed time period of the leading part of the slot or frame, and to the signal P 2 for other time periods, etc.", "In another example, control unit 9 may provide control for peak suppression in accordance with calculation results yielded by PAPR suppression signal calculation unit 4 .", "For example the PAPR suppression signal calculation unit 4 may provide input to the control unit 9 .", "Therefore the multiplexed signals to be input into transmission amplification unit 2 and amplified are in a peak-suppressed state and it is possible to suppress the unneeded radiation component.", "Moreover, both P 1 and P 2 are processed by the same spread unit 6 therefore the spread code is applied the same code.", "In this case it should be noted that P 1 and P 2 are not transmitted by switching unit 8 with any temporal overlap.", "Also, in spread unit 6 , P 1 can be transmitted with multiple spread codes, but P 2 can be transmitted with one spread code among the multiple spread codes.", "Also, with regard to the frequency relationships as well, P 1 and P 2 are both transmitted on the same frequency.", "And although, P 1 can be transmitted with multiple frequencies, but P 2 can be transmitted with one frequency among the multiple frequencies.", "In the CDM system or the OFDM system, the processed pilot signal “pilot”", "which is a known pattern or signal is transmitted.", "For data reception processing, the receiver can correlate transmission paths because the receiver can obtain radio transmission path status information from the received and divided pilot signal.", "By using a known signal for example pilot signal this invention does not need a channel etc, to transmit a special signal for suppressing PAPR.", "The receiver divides the second signal P 2 from the received signal to use the first known signal, for example pilot signal etc.", "And also, the receiver corrects the phase and amplitude of the second signal P 2 so as to correct all pilot signal 1 is known signal, therefore the receiver is able to correct propagation path correction, etc.", "FIG. 2 is an explanatory diagram of an example of a first pilot signal P 1 and a second pilot signal P 2 as the known signals referred to above;", "Assuming the modulation system for the case in which a pilot signal is to be transmitted by QPSK modulation.", "If the known pilot signal is signal point (1,1), then conventionally a pilot signal is transmitted as this signal point (1,1) multiplexed together with the data, etc.", "But in this working example, a first pilot signal P 1 is transmitted in every prescribed time period for the pilot signal which is the known signal point (1,1).", "In order to make it possible for PAPR suppression to be done by PAPR suppression signal calculation unit 4 , after this first pilot signal P 1 is transmitted, one of the four signal points (1,1), (1,−1), (−1,1), (−1,−1) is selected and processed;", "that is, it is transmitted as second pilot signal P 2 in a phase-controlled state.", "Moreover, a single or plural of the first pilot signal P 1 is always transmitted every prescribed time period, and during this first pilot signal P 1 , second pilot signal P 2 is transmitted multiplexed onto the time axis (here too, without temporal overlap).", "The time interval for first pilot signal P 1 should be selected so as to allow the phase change due to the wireless propagation path during this period to be ignored to some extent.", "On the receiver side, the phase of second pilot signal P 2 can be corrected by taking the phase of first pilot signal P 1 as a reference, making possible restoration to pilot signals of a known phase relationship.", "Therefore correction processing can be done on the received data by a reception-side propagation path correction means using the pilot signal.", "In this way, PAPR suppression is done by transmitting a pilot signal in which a first pilot signal P 1 and a second signal P 2 are combined on the time axis (for example, combined without temporal overlap), and on the receiver side, as shown in FIG. 3 , this pilot signal is set so as to be able to ignore the phase change of the second signal P 2 received during the first pilot signal P 1 of known pattern, and because the second pilot signal P 2 is one of the four signal points (1,1), (1,−1), (−1,1), (−1,−1), processing can be done that returns it to known signal point (1,1) of the first pilot signal P 1 .", "Therefore processing as a pilot signal can be done in the same way as in the case in which an ordinary pilot signal undergoes reception processing.", "In the aforesaid case, the second signal P 2 , for which the first pilot signal P 1 is phase-rotated in 90-degree units so as to obtain a PAPR suppression effect in order to effect PAPR suppression, is set to a phase that corresponds to the calculation results in PAPR suppression signal calculation unit 4 , but the transmission can be done with this second signal P 2 phase-rotated in units of θ=360/n (where n is an integer greater than or equal to 2).", "For example, if we set n=2, then second signal P 2 can be transmitted selected from the calculation results in PAPR suppression signal calculation unit 4 from the two choices 0 degrees and 180 degrees, and if we set n=4, it can be selected from the four phase rotations referred to above.", "In this case, the higher the value n is set to, the greater the number of choices that can be selected, so the PAPR suppression effect can be improved.", "FIGS. 4( a ) and 4 ( b ) are explanatory diagrams of the phase change;", "in 4 ( a ), if the phase change is large as indicated by the dotted-line arrow, then if the selection phase θ of second signal P 2 is made small and the number of choices is made large, then on the receiver side the phase change in the wireless propagation path and the selection phase of second signal P 2 will come to approximate each other, and reception demodulation of second signal P 2 may be difficult.", "In that case, the selection phase θ of second signal P 2 is made large.", "That is, the n in θ=360/n is set to a small value.", "By this, reception demodulation of second signal P 2 becomes easier.", "And as shown in FIG. 4( b ), if the phase change is small as indicated by the dotted-line arrow, then even if the phase rotation θ is made small, that is, even if the n in the aforesaid θ=360/n is set to a large value, then reception demodulation of second pilot signal P 2 will be easy, and because the selection of phases can be made finer, the PAPR suppression effect can be improved.", "In FIG. 1 , amplitude control (amplitude control unit not pictured) can be provided that controls the amplitude of first pilot signal P 1 , second signal P 2 , or both, according to the calculation results given by PAPR suppression signal calculation unit 4 .", "For example, if the amplitude is to be controlled with respect to second signal P 2 , then on the receiver side the amplitude of second signal P 2 can be corrected based on the reception demodulation results of first pilot signal P 1 .", "Also, both the phase and amplitude of second signal P 2 can be controlled in correspondence with the calculation results given by PAPR suppression signal calculation unit 4 .", "For the amplitude of first pilot signal P 1 as well, PAPR suppression can be done by controlling it.", "In FIG. 5 , which shows the composition of the main parts of the reception unit of a wireless communication device to which the CDM system is applied, 11 is a pilot signal despread unit, 12 and 13 are switching units, 14 is a pilot signal compensation unit, 15 is a pilot signal compensation quantity calculation unit, 16 is a data despread unit, 17 is a propagation path correction unit, and 18 is a control unit.", "Omitted from the diagram are the makeup of the reception antenna, demodulation unit, and other high-frequency processing parts and the processing units for reception data, etc.", "By control unit 18 , switching operations are carried out in such a way that during the reception time period of first pilot signal P 1 , switching units 12 and 13 are set to the switching state shown in the diagram, and during the reception time period of second signal P 2 , switching unit 12 is connected between pilot signal despread unit 11 and pilot signal compensation unit 14 , and switching unit 13 is connected between pilot signal compensation unit 14 and propagation path correction unit 17 .", "If a pilot signal pattern that shows the transmission time periods of the first and second pilot signals P 1 and P 2 is preset, the switching control of switching units 12 and 13 by this control unit 18 follows this pattern, and if it changes adaptively, switching control can be done in correspondence with the transmission time periods of first and second pilot signals P 1 and P 2 by receiving control information that indicates the pilot signal pattern.", "Moreover, although there is no need to detect the reception time period of the first pilot signal, various methods can be applied.", "For example, a wireless communication device that transmits the first pilot signal can be detected by taking the signals of separate transmitting channels as distinguishing marks.", "For example, it can be arranged that the first pilot signal is transmitted from the time when a signal of a separate channel corresponds to a part that constitutes a specified signal pattern (the same timing as that part, or a time that is a prescribed time before or after that part), and by detection of the specified signal pattern on the receiver side, the start of the first pilot signal that is inserted periodically can be detected.", "Also, if it is set up so that the first pilot signal is transmitted multiply and continuously, then by receiving the same signal multiple times in a row, it can be detected that it is the first pilot signal, and that the continuous time period is the transmission time period of the first pilot signal.", "At that time, in consideration of the fact that the second pilot signal also will be the same signal continuously, the transmission time period of the first pilot signal can be detected by the fact that the continuous time period appears repeatedly multiple times with a known periodicity.", "And if the first pilot signal is transmitted periodically, then if it can be detected for multiple periods that the same signal can be received periodically, it will be possible to detect the transmission time period of the first pilot signal.", "The first pilot signal P 1 and the second signal P 2 undergo despread processing in pilot signal despread unit 11 according to the spread code assigned to the pilot signal, and by the switching state of switching units 12 and 13 that is pictured in the diagram, first pilot signal P 1 is input into pilot signal compensation quantity calculation unit 15 and propagation path correction unit 17 .", "And in the same way as in the case of an ordinary pilot signal, data that undergoes despread processing by data signal despread unit 16 is corrected in propagation path correction unit 17 and is transferred to a later-stage processing unit that is not pictured in the diagram.", "In the time period that corresponds to the transmission time period of second signal P 2 , switching units 12 and 13 are switched from the state pictured in the diagram, second signal P 2 is input into pilot signal compensation unit 14 , in pilot signal compensation quantity calculation unit 15 , compensation of the phase rotation, etc.", "corresponding to second signal P 2 is done based on the compensation quantity for the phase rotation, etc.", "corresponding to second signal P 2 for which the first pilot signal P 1 is taken as the reference, and it is input into propagation path correction unit 17 as a pilot signal of the same known pattern as the first pilot signal.", "Therefore by taking second signal P 2 as a pilot signal of the same known pattern as first pilot signal P 1 , correction of the propagation path properties can be done with respect to the data.", "FIG. 6 shows the configuration of the principal parts of the reception unit of a wireless communication device to which is applied a CDM system in which part of the configuration shown in FIG. 5 has been modified;", "the same symbols as in FIG. 5 denote the same named parts.", "Moreover, control unit 18 has been omitted from the diagram.", "Also, in the configuration shown in FIG. 5 , the case is shown in which first pilot signal P 1 is used and then compensation of second signal P 2 is done, but in FIG. 6 it has a configuration in which second signal P 2 compensated by pilot signal compensation unit 14 is also input into pilot signal compensation quantity calculation unit 15 , and compensation of second signal P 2 is done.", "FIG. 7 is an explanatory diagram for the transmission ratio of first pilot signal P 1 and second signal P 2 ;", "taking symbol M of first pilot signal P 1 and symbol N of second signal P 2 as pilot frames, these pilot frames can be transmitted repeatedly.", "As stated above, the length of the pilot frame in this case can also be set to a time period that is long enough so that the phase change in the transmission time period of second signal P 2 during first pilot signal P 1 can be ignored.", "Also, it is usual to set the ratio M/N of first pilot signal P 1 and second signal P 2 to a preset value, but this could also be varied based on the state of the wireless propagation path, etc.", "FIG. 8 (A) shows the case in which a pilot signal is used in which, within one pilot frame, first pilot signal P 1 - 1 is arranged as symbol M, then second signal P 2 is arranged as symbol N, then first pilot signal P 1 - 2 is arranged as symbol L;", "their ratio M/N/L can be set to a preset value.", "Also, as stated above, the interval between first pilot signals P 1 - 1 and P 1 - 2 can be set to a time period whereby the phase change can be ignored.", "In FIG. 8(B) , (a) and (b) are an explanatory diagram for the case in which there is an interval in which no pilot signal is transmitted;", "(a) shows the case in which the pilot signal pattern shown in FIG. 7 is used, and (b) shows the case in which the pilot signal pattern shown in FIG. 8 (A) are used.", "If the phase change in the interval during which no pilot signal is transmitted is large, in the case of the pilot signal pattern shown in (a), the end of the interval during which there is no transmission is second signal P 2 , and in the case of the pilot signal pattern shown in (b) it is first pilot signal P 1 - 2 , so the demodulation processing of second signal P 2 in the reception-side demodulation of the pilot signal has the advantage of having better demodulation precision than the case shown in (a).", "FIG. 9 (A) shows the case in which pilot signals are repeatedly transmitted in a pattern where the ratio between first pilot signal P 1 and second signal P 2 changes as M 1 :N 1 , M 2 :N 2 , M 3 :N 3 .", "If pilot signals are transmitted by a pattern in which the ratio is changed with each pilot frame in this way, it can be done by controlling switching unit 8 by control unit 9 in FIG. 1 .", "If such switching control is applied to, for example, a wireless communication system that performs synchronization using pilot signals, then by using a pilot frame in which first pilot signal P 1 has a high ratio, the receiver side can perform synchronization with greater precision than if a pilot frame of another ratio were used.", "FIG. 9(B) shows as Case 1 and Case 2 , the ratio of first pilot signal P 1 and second signal P 2 in the pilot frames is made different, and which of Case 1 and Case 2 to adopt can be changed adaptively.", "For example, when it is determined in PAPR suppression signal calculation unit 4 (see FIG. 1 ) that the PAPR is large, or when there are many spread codes in the CDM system, then Case 2 is selected, which includes many second signals P 2 for carrying out PAPR suppression, and when it is determined that the PAPR is small, or when there are few spread codes in the CDM system, then Case 1 is selected, which includes many first pilot signals P 1 , and in order to notify the receiver side of this pilot signal pattern, notice is given to the receiver side by control information, for example setting Case 1 =0, Case 2 =1 by a one-bit configuration.", "Moreover, if a selection is to be made from among a larger variety of pilot signal patterns by the two types Case 1 and Case 2 , the receiver side can be given notice of the pilot signal pattern by a number of bits that corresponds to the number of types.", "This amounts to, for example, doing switching control of switching units 12 and 13 by reception-side control unit 18 shown in FIG. 5 .", "FIG. 10 shows cases in which the pilot frame is not fixed but is variable;", "Case 1 and Case 2 depict the case in which the length of the pilot frame is the same and the ratio of first pilot signal P 1 and second signal P 2 is different, while Case 3 and Case 4 depict the case in which the length of the pilot frame is shorter than in Case 1 and Case 2 .", "The selection from among Case 1 to Case 4 can be made according to the following conditions.", "Case 1 : if it is anticipated that the phase change in the wireless propagation path is small and the PAPR is small;", "Case 2 : if it is anticipated that the phase change in the wireless propagation path is small and the PAPR is large;", "Case 3 : if it is anticipated that the phase change in the wireless propagation path is large and the PAPR is small;", "Case 4 : if it is anticipated that the phase change in the wireless propagation path is large and the PAPR is large.", "That is, if the phase change of the communication path that includes the wireless propagation path is large, the precision of the pilot demodulation signal on the receiver side can be improved by making the pilot frame smaller.", "If the pilot signal pattern is varied adaptively in this way, by notifying the receiver side of the control information, it is possible on the receiver side to do reception processing on the first and second pilot signals P 1 and P 2 and return the second signal P 2 to first pilot signal P 1 .", "FIG. 11 (A) shows the results of a simulation of the peak suppression effect, and FIG. 11(B) shows the results of a simulation of a conventional example and of this invention.", "FIG. 11 (A) shows the PAPR suppression effect if one applies high-speed downlink packet access (HSPDA) for speeding up the transmission rate of the downlink in the wideband-code division multiple access (W-CDMA) system;", "it shows the results of a computer simulation, given that the transmission signal is set to 24-code multiplex, the pilot channel for peak power suppression is set to a common pilot channel (CPICH), and the ratio of the CPICH power to the total transmission power is set to 0.1.", "The peak to average power ratio (PAPR) is plotted along the horizontal axis, and the cumulative probability is plotted along the vertical axis.", "“With peak suppression”", "in the diagram is the result if the ratio of the first pilot signal P 1 to second signal P 2 in this invention is set to 1:9.", "It is seen that there is a peak suppression effect of about 0.8 dB at a cumulative probability of 10 −4 .", "FIG. 11 (B), like in FIG. 11(A) , shows the results of a simulation if HSPDA is applied and the travel speed of the mobile wireless communication device is set to 3 km/h;", "Ior/Ioc (the ratio of own-cell power to multi-cell power on the receiver side) is plotted along the horizontal axis, and the throughput of the high-speed downlink shared channel (HS-DSCH) is plotted along the vertical axis.", "In this invention, because peak suppression is done using a pilot signal by CPICH, there is no need to set up a new channel for peak suppression as in a conventional example, so the HS-DSCH power can be allocated just for the portion of the channel for peak suppression of the conventional example.", "As a result, it is clear that in this invention the signal-to-interference ratio (SIR) of the HS-DSCH is greater, and the throughput is better, than in the conventional example.", "By changing from the PAPR suppression means of the conventional example to the PAPR suppression means of this invention, the rate of throughput increase becomes about 10% in the region where or/Ioc=15 dB or less.", "For the known signals referred to above, the explanation has dealt mainly with the case in which a pilot signal is used in the CDM system, but a pilot signal and other known signals in a multiplexing transmission system such as the OFDM system can be transmitted as a first known signal and a second signal that controls the phase or amplitude or both so as to perform PAPR suppression.", "Also, it is a concept of whether a channel is the same or different, but if the transmission frequency and spread code are the same, it can be deemed to be the same channel, even if the transmission times are different.", "That is, for example, in FIG. 1 , although the transmission part of P 1 and the transmission part of P 2 differ temporally, their transmission frequency and spread code are the same, and both P 1 and P 2 can be deemed to be being transmitted on the same channel (pilot channel).", "This invention provides advantages because it transmits together on the time axis known signals and signals that are processed with respect to the known signals so as to be able to suppress the peak to average power ratio.", "Also, it makes use of part of a channel that transmits known signals, with this invention it is unnecessary to newly introduce a special channel for peak suppression.", "There is no need to newly allocate for suppression purposes any frequency that is different from the channel that transmits known signals, or any different spread code." ]
FIELD OF THE INVENTION This invention is directed generally to irrigation systems for irrigating large land areas and more specifically is directed to elongated irrigation systems that move in substantially controlled manner over a land area to accomplish irrigation of the land area. More specifically, the present invention is directed to an irrigation system that extracts water from an elongated water supply source, such as a ditch or water pipe, for the purpose of irrigation and which irrigation system is automatically movable and automatically steered over a land area for extended lengths of time without any requirement for significant attention by personnel. BACKGROUND OF THE INVENTION A valuable asset to the irrigation industry has been the development of irrigation systems that travel while sprinkling large land areas with water and require virtually no personnel attention during operation. Substantial elimination of the labor costs that were earlier required has greatly enhanced the commercial success of large field irrigation. Although many different types of irrigation systems have been developed over the years, the type of irrigation system that is most prevalent is the circular irrigation system which incorporates a plurality of sprinkler pipe sections that are each supported by a mechanism for inducing movement to the pipe sections. In circular irrigation systems a central pivot tower is provided that also serves as a water supply and one extremity of the irrigation system is connected thereto causing the entire irrigation system to revolve about the pivot during continuous irrigation operations. Although circular irrigation systems have been quite successful, it is clear that greater crop yields and lower cost irrigation would be achieved if the irrigation system were capable of irrigating rectangular land areas or other specifically shaped land areas as opposed to circular areas. One attempt to accomplish more rectangular irrigation through the use of circular irrigation systems is through the use of corner irrigation spray devices that are activated only during four small segments of each revolution of the irrigation system. Although the increase of land area irrigation through the use of irrigation guns is not insubstantial, it would nevertheless be commercially desirable to provide an irrigation system that was capable of irrigating the entirety of a large rectangular land area. In the past, irrigation systems have been developed for irrigation of rectangular fields, but in order to provide for proper operation of the irrigation system, it is generally deemed necessary that a plurality of tracks or guideways be provided in order to physically guide the irrigation system over the land area. Of the number of patented devices that have been developed with track or guideway control in mind, U.S. Pat. No. 3,608,827, to Kinkead is typically representative. Linearly movable irrigation systems have also been developed that do not necessitate the use of tracks or guideways such as taught by U.S. Pat. No. 3,613,703, to Stout which utilizes a guide rail 52 for reference during movement over a land area and traverses by alternate movement and pivoting of each of the ends of the system. In the case of the structure identified in the patent to Stout the ambulatory irrigation system is so arranged and controlled that each end of the composite line alternately can be caused to travel a predetermined distance along an arcuate path with the opposite end of the composite line temporarily being substantially at the center of curvature of the arcuate path and with the entire line thus swinging forwardly in alternate angular direction as it moves over the land area. More simply, one extremity of the irrigation system remains static and serves as a pivot during a portion of the movement and the sequence is then reversed causing the other extremity to remain static while the first extremity is caused to move. The ends of the system are not capable of simultaneous movement. It is considered desirable to provide a linearly movable irrigation system that does not require a track or guideway to control movement thereof such as is the case with Kinkead U.S. Pat. No. 3,608,827 and which does not cause excessive water distribution on certain of the land section such as is likely to occur when each end of the irrigation system alternately moves forward. U.S. Pat. No. 3,707,164 to Clemons and U.S. Pat. No. 3,974,845 to Indresaeter disclose linearly movable irrigation systems which do not require a track or fixed guideway for control of the system movement. Clemons teaches a method and apparatus for maintaining an irrigation system within predetermined distance from an elongated reference line. In one embodiment, Clemons selectively energizes adjacent tractors to provide a steering action relative to the guide and in another embodiment the tractor wheels are also turned simultaneously to move the irrigation system toward or away from the reference guide. Clemons also teaches maintaining the alignment between adjacent tractors by varying the flow of hydraulic fluid to hydraulic motors on the tractors for speed control. It should be noted that the steering control systems taught by Clemons employ control and power systems at substantially each mobile support unit. Further, the control systems of Clemons are actuated by only a single type of input so that the system response is corrective of only the particular input selected. U.S. Pat. No. 3,974,845 to Indresaeter teaches an irrigation system which is controlled by stopping and starting mover units located at extremities of the system. As described therein, the control system is provided with inputs functionally related to the linear displacement from the guide reference of the mover unit adjacent the guide reference and to the angular alignment of the irrigation system with respect to the guide reference. The correction of either linear or angular misalignment is accomplished by causing the entire irrigation system to pivot about one extremity or the other to maintain the system within preselected limits. Lateral displacement can be corrected only by a substantial number of correcting manuevers. Further, there is no input signal related to the stresses being developed in the irrigation pipe spans in order to preclude corrective action which could result in excessive system stresses. Accordingly, it is a primary feature of the present invention to provide a novel linearly movable irrigation system that moves in substantially linear manner over a land area and is capable of irrigating the entirety of a generally rectangular land area or irrigating a land area of an irregular shape. It is also a feature of the present invention to provide a novel linearly movable irrigation system whereby control of the movement of the system is accomplished by a first control system steering a mover unit adjacent an elongated reference and an independent second control system maintaining the relative rotation of the irrigation pipe spans relative to the steerable mover unit. It is an even further feature of the present invention to provide a novel linearly movable irrigation system that moves in linear manner over a land area and, in the event of the occurrence of predetermined misalignment of the irrigation system relative to the reference, the irrigation system is automatically self-steering to maintain its travel within a defined boundary. It is yet another feature of the present invention to provide a novel linearly movable irrigation system employing sensing devices for determining angular alignment of the irrigation pipe spans with respect to a pivot located on the steerable mover unit and for determining the stresses in the irrigation pipe spans and controlling the angular alignment and stress by movement relative to the steerable mover unit. It is also an object of the present invention to provide a novel linearly movable powered mover unit adjacent a reference such as an elongated guide surface which may be straight or curved as desired, wherein the powered mover unit is provided with a control mechanism that senses linear displacement of the mover unit relative to the reference for steerably controlling travel of the mover unit relative to the elongated reference. It is another object of the present invention to provide a novel linearly movable irrigation system in which angular alignment and stresses in the irrigation pipe spans are controlled by movement relative to a powered mover unit and independent from a fixed guide reference. It is also a feature of the present invention to provide a novel linearly movable irrigation system wherein a plurality of individually supported and driven sections are incorporated into an elongated irrigation system and wherein movement of each of the sections is controlled by its angular relationship with an adjacent irrigation section, such angular relationship control overridden under certain circumstances by control signals received from a power and control portion of the irrigation system. SUMMARY OF THE INVENTION The present invention is directed to a linearly movable steerable irrigation system that is adapted to move in substantially linear manner for irrigation of a large generally rectangular land area. The irrigation system is adapted to move automatically in response to its position relative to an elongated reference such as an elongated straight or curved guide surface, guide rail, guide line or guide beam during irrigation operations and in response to the angular alignment and stresses of irrigation pipe spans relative to a powered mover unit adjacent the elongated reference. Sensing apparatus carried by a powered mover unit of the irrigation system is capable of sensing both linear displacement of the mover unit relative to the elongated reference and the angular alignment and stresses of the irrigation pipe spans relative to the powered mover unit and automatically self-correcting the direction of movement in the event the irrigation system has moved beyond allowable limits of linear displacement, angular misalignment or system stresses. The irrigation system includes a powered mover unit that is provided at one extremity thereof or intermediate the extremities of the system and which will typically be directly connected to linear displacement, angular misalignment, and system stress sensors that determine relative positioning of the irrigation system. To the powered mover unit may be connected a plurality of irrigation sections each comprising an irrigation span that is supported by any suitable mobile support such as wheels, tracks, ambulatory mechanisms, etc. that is capable of accomplishing movement of the irrigation system over the land area. An elongated irrigation conduit being a composite of a number of interconnected sections of irrigation pipe will be supported by the spans above the land area and will cause distribution of water on the land area by means of sprinkler devices carried by the various sections of water supply pipe. Each of the self-driven sections or spans of the irrigation system may be controllably activated and deactivated by the angular relationship thereof to other spans or sections to accomplish controlled movement of the spans of the irrigation system. Conventional angular detection sensors may be employed to detect angular misalignment between the respective sections of the irrigation system. When such angular misalignment reaches a predetermined value, the drive mechanisms controlled by the angular detecting device for each section will be energized causing the drive means to impart driving movement to that particular section of the irrigation system. Such driving will continue until sufficient movement of that section has occurred to change the angular relation detected by the angular detecting device to another predetermined value, at which time the drive mechanism for that irrigation section will be de-energized. For accomplishing steering control responsive to signals received by the powered mover unit from the linear displacement sensors contacting the elongated reference, steering pistons on a steerable powered mover unit are actuated to rotate the mobile support, such as wheels, and maintain the steerable powered mover unit within preselected displacement limits of the elongated reference. Hence, continuous irrigation system movement can be maintained when minor steering corrections are being made and the system is enabled to promptly respond to correcting signals. Extending from the steerable mover unit may be a plurality of irrigation pipe spans and a powered mover unit connected substantially at the extremity of the connected pipe spans. The extending pipe spans may be pivotally connected to the steerable mover unit to define a reference for measuring angular alignment of the irrigation spans with the steerable mover unit and for measuring stresses within the pipe spans as a function of the reference pivot. The angular alignment and stresses of the irrigation pipe spans are maintained within preselected limits by varying the average speeds of the steerable mover unit and the outboard mover unit to obtain rotation of the extending pipe spans relative to the pivot. For example, mover unit average speed may be varied by controlling the duration for energizing the mover unit motor over a selected time interval, i.e. controlling the duty cycle of the motor. Varying the duty cycle of the inboard and outboard mover unit motors will produce relative pivotal movement of the outboard unit about the inboard unit. When this relative pivotal movement has continued sufficiently to satisfy the requirements of the control signal, another control signal will be provided causing both extremities of the irrigation system to move at the same or different average speed, causing the entire irrigation system to move in substantially linear or controllably turning manner across the land area. Upon movement of the irrigation system sufficiently to traverse control boundaries defined by the stress and angular misalignment sensors, another control signal will be issued, causing the opposite extremity of the irrigation system to remain static or to be controllably slowed while the other extremity of the irrigation system is allowed to continue moving. The resulting effect is a relative pivoting of the entire irrigation system about the steerable mover unit. In other words, the irrigation system will move across the land area in substantially linear manner unless for some reason it should become over-stressed or angularly misaligned relative to the steerable mover unit. This can be caused by traversing of the irrigation system over undulations in the terrain or by other than straight line positioning of the reference such as might occur if the reference is designed to cause tracking of the irrigation system to irrigate an oval land area. The present invention is also directed to the method of accomplishing irrigation of land areas, wherein the elongated irrigation system, capable of movement across a land area in substantially linear manner, is also capable of being steered automatically so as to correct any lateral displacement from an elongated reference. The irrigation apparatus, under the novel method of controlling the operation thereof, is capable of irrigating generally rectangular land areas and because of its automatic steering capability, is also capable of traversing land areas that are of irregular configuration. Each extremity of the irrigation system is capable of independent movement responsive to control signals received from a control facility and may move at different speeds, stop, or move at the same speed as the opposite extremity of the irrigation system. Also, the power and control facility for the irrigation apparatus may be located intermediate the extremities of the irrigation system or at either extremity thereof within the teachings of the present invention. Water supply for the irrigation system may take the form of an elongated ditch from which water is extracted by suction or it may take the form of an elongated closed water supply system such as a pipe having a plurality of water supply connections that are automatically received and released in such manner as to provide substantially continuous water flow as the irrigation system traverses its designated path of travel. BRIEF DESCRIPTION OF THE DRAWINGS So that the manner in which the above-recited features, advantages and objects of the present invention as well as others which will become apparent, are obtained and can be understood in detail, more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings, which drawings form a part of this specification. The present invention, both as to its organization and manner of operation may best be understood by way of illustration and example of certain preferred embodiments when taken in conjunction with the accompanying drawings. IN THE DRAWINGS FIG. 1 is a plan view partially in schematic form illustrating a linearly movable irrigation system that is constructed in accordance with the principles of the present invention. FIG. 2 is a plan view of a motorized steerable mover unit and illustrating the position of the various sensors on the mover unit frame. FIG. 3 is an elevation view illustrating one embodiment of a displacement sensor for determining the position of the mover unit frame relative to an elongated reference. FIG. 4 is a schematic illustration of control system input parameters. FIG. 5 is a schematic illustration of the basic control system logic. FIG. 6 is a graphic representation of the track of controlled movement of the irrigation system in response to various input signals. FIG. 7 is a block diagram schematic of a control unit for evaluating input information and determining an appropriate response in accordance with a preferred embodiment of the present invention. DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings and first to FIG. 1, there is depicted a self-driven irrigation system of the type that is adapted to move across a large land area to be irrigated and to follow elongated reference while controlling an extending string of irrigation pipe spans to maintain the stresses in the irrigation pipe spans and the rotation of the elongated string of pipe within predetermined values. As shown in FIG. 1, the irrigation system incorporates a motorized steerable mover unit depicted generally at 10. On the mover unit 10 may be provided an engine, pump, and generator unit 22 providing mechanical and electrical power for operation of the irrigation system. Mover unit 10 is in communication with a water supply source 14 and may extract water from the water supply and transmit it under pressure to a plurality of irrigation spans 16 from which it is evenly distributed on the land surface by a plurality of conventional sprinkler devices that are carried by the irrigation pipe spans. Extending from the mover unit 10 are a plurality of irrigation sections or spans 16 that comprise a structural framework for support of each of the various sections of irrigation water supply pipe that are interconnected to form the irrigation system. Each of these spans or sections 16 may be supported by a mobile base 17, the respective mobile bases 17 being provided with wheels, tracks, ambulatory devices, etc. in order to provide the mobility that causes the irrigation system to traverse the land area being irrigated. An outboard mover unit 18 is provided preferably adjacent the end of the irrigation span removed from water supply 14. Mover unit 18 may be provided with an individual power means which is controlled so as to permit rotation of the plurality of interconnected irrigation pipe spans 16 with respect to the steerable mover unit 10, as will be hereinafter explained in more detail. For controlling the track of the irrigation system over the land area, an elongated reference 12 may be provided. The elongated reference may take many suitable forms that enable position sensing devices to react with the reference and steer the steerable mover unit to maintain a predetermined distance between the steerable mover unit and the elongated reference 12. For example, the reference may be a guide rail supported above the ground on posts, it may take the form of a supported guide wire and it may also take the form of a guide surface formed by the water supply, such as an external wall of a concrete lined ditch that is partially embedded in the ground or supported on the surface of the land area. The reference, where a straight line reference is desired, may take the form of a laser beam or other suitable beam that may be appropriately sensed. If the novel sensing device, hereinafter described, which is subject of the present invention is employed, a supported guide wire is the preferred form of the elongated reference 12. While the reference 12 is shown to be in the form of a straight line in FIG. 1, it is not intended to limit the present invention solely to use under conditions where the reference takes the form of the straight line. The reference 12 may be curved in any suitable form that is appropriate for guiding the track of the irrigation system about the land area to be irrigated. Referring now to FIG. 2, there may be seen a plan view of steerable mover unit 10. A frame 34 is provided which is mounted on a suitable mobile support for traversing a terrain suitable for irrigation, which mobile support may conveniently take the form of wheels 38 supported on axles 36 which are rotatably mounted on frame 34. Wheels 38 may be rotated to steer mover unit 10 either toward or away from elongated reference 12 so as to maintain a predetermined distance between the mover unit 10 and elongated reference 12. Sensor units 30 may be mounted on sensor support arms 40 which are connected to the wheel axles 36 which are nearest the elongated reference 12. In operation, the leading sensor 30 at each wheel location is selected to provide an input signal, the leading sensor being determined by the direction of travel of mover unit 10. Electrical output lines 32 from each sensor 30, conveniently carried in cable bundle 33 mounted on frame 34, provide a plurality of output signals from each sensor 30 as inputs to control unit 24. Electrical outputs 32 from sensors 30 are used to control the steering mechanisms 44 and 42 and control the position of mover unit 10 relative to elongated reference 12. Tie rods 37 connect the pair of wheel axles 36 at each end of mover unit 10 so that simultaneous movement of each pair of wheels 38 will occur. Steering actuators 42 and 44 may conveniently take the form of hydraulically-actuated pistons which are actuated through hydraulic output lines 45, which may conveniently be interconnected with the output of the water pump (not shown) contained in engine section 22. Actuators 42 initiate movement of mover unit 10 away from elongated reference 12, whereas actuators 44 initiate movement toward elongated reference 12. In a preferred embodiment, a sensor 30 will activate the steering mechanism for the pair of wheels 33 on which it is mounted. In this manner, each end of mover unit 10 will move toward or away from elongated reference 12 as determined from the outputs from sensors 30. A particular displacement sensor contemplated as part of the present invention may be seen by reference to FIG. 3, as more particularly hereinafter discussed. In FIG. 2 there may also be seen engine section 22 which is depicted in block form. Engine section 22 may contain a motor powered by conventional fuel sources such as gasoline, butane, diesel fuel, etc. and interconnected with a conventional generator for supplying electrical energy to power mover unit 10 and other mover units interconnected therewith. The engine may be conventionally connected to a pump via a power take-off unit to provide a pressurized supply of water to the irrigation pipe spans for suitable distribution through sprinklers to the land area. A portion of the pump output may be diverted through hydraulic lines 45 to activate steering actuators 42 and 44, as hereinabove discussed. The output from the electrical generator is supplied to electrical motors for powering the mover units, and may be controlled as hereinbelow discussed to maintain movement of the irrigation system across the land area. Referring again to FIG. 2, there may be seen a pressurized water supply pipe 26, connected to the output of the pump and engine section 22 and suitably supported on frame 34 by a tower-like support structure (not shown). Water pipe 26 is connected to pivot section 28 and thereafter interconnected with irrigation pipe span 16. Pivot 28 defines a reference point with respect to the plurality of irrigation pipe spans 16 which extend outwardly from pivot 28 and which interconnect with mover unit 18, as depicted in FIG. 1. As hereinafter described, the rotation of irrigation pipe spans 16 about pivot 28 is measured by rotary transducer 50 which provides an output signal 52 which is functionally related to the amount of angular rotation of irrigation pipe span 16 about pivot 28. Pivot 28 is mounted on frame 34 so that pivot 28 may be deflected along the line of the interconnected irrigation pipe span 16. The direction and amount of deflection of pivot 28 is functionally related to the tension and compression stress forces which occur in the string of interconnected irrigation pipe spans 16. Control of these stress forces is important to maintaining control of the irrigation system, as more fully discussed hereinbelow. The deflection of pivot 28 is detected by deflection linkage 54 and translated into a rotary movement which is detected by deflection rotary transducer 56. Deflection transducer 56 thereby provides an electrical output signal 58 which is functionally related to the magnitude and direction of the stresses which are obtained in the interconnected irrigation pipe spans 16. The extending irrigation pipe spans 16 must be maintained in a relationship to adjacent pipe spans to permit movement about pivot 28 to functionally represent the condition of the entire pipe string. Such a relationship is maintained by sensing the angular relationship between adjacent pipe spans and controlling the intermediate mobile bases 17, as shown in FIG. 1, to correct misalignment on a span-to-span basis. The intermediate mobile bases 17 are normally energized and then controllably de-energized to maintain each span 16 within a preselected angular relationship with adjacent spans. The entire extending pipe string is thereby maintained as a substantially straight line so that pivot 28 may be used as an appropriate reference. The outputs 52 and 58 from pivot rotation transducer 50 and deflection transducer 56, respectively, are provided as inputs to control unit 24 to obtain a first output 60 to control the motor of inboard mover unit 10 and a second output 62 which controls the motor of outboard mover unit 18 which is displaced from mover unit 10. It is readily apparent from the foregoing discussion that, according to the present invention, movement of the irrigation system in a controlled fashion is accomplished by first steering mover unit 10 with respect to an elongated reference 12 to independently establish the track of mover unit 10 across the land area which is to be irrigated. The interconnected plurality of irrigation pipe spans 16 is then maintained in a controlled relationship with respect to mover unit 10 by controlling mover unit 18 which may conveniently be located near the end of the interconnected spans of irrigation pipe. As fully discussed hereinbelow for FIGS. 4 and 5, the relationship between the extending irrigation pipe spans and the steerable mover unit 10 permits the string of irrigation pipe to be maintained in a generally perpendicualr relationship with respect to elongated reference 12 and yet allow some variation in its angular relationship to provide corrective movement which relieves stresses occurring along the interconnected pipe spans. Referring now to FIG. 3, there is shown displacement sensor 30 according to one embodiment of the present invention. Displacement sensor 30 includes an elongated sensor support member 70 which is mounted on mover unit 10 by pivotally connecting elongated sensor support member 70 to displacement sensor support 40. Elongated sensor support 70 is eccentrically mounted at pivot 78 to displacement sensor support frame 40. The eccentric location of pivot 78 is provided so that elongated sensor support 70 will assume a preselected angle with respect to the vertical when in a free hanging condition. As explained below, the free hanging angle is a limit which determines a maximum displacement of mover unit 10 from elongated reference 12. As mover unit 10 traverses the land area to be irrigated, sensor support member 70 contacts elongated reference 12 and rotates about pivot 78 as mover unit 10 moves variably in relationship to its displacement from elongated reference 12. A plurality of switches are mounted on elongated reference 70 which are selectively energized to detect the angular position of elongated sensor support 70. As depicted in FIG. 3, switches 72, 74 and 76 illustrate the relationship of switch outputs to various angular conditions. Position A of FIG. 3 depicts movement of mover unit 10 toward elongated reference 12. Switches 76 and 74, which may conveniently take the form of mercury limit switches in which contact is completed when mercury pools in one end or the other, are rotated so as to complete the circuits connected therewith (not shown). Switch 72 has moved to a level position where the mercury is pooled in an intermediate location so that contact is not made at either end of switch 72. The output from switches 76 and 74 may be used to activate the steering mechanism as hereinabove discussed to steer mover unit 10 away from elongated reference 12 until elongated sensor support 70 reaches position B. At condition B, sensors 76 and 72 now have completed electrical contacts and sensor 74 is in the intermediate condition. The output from the position B condition may be used to activate the steering mechanism to return the wheels to a neutral position. If mover unit 10 begins to drift away from elongated reference 12, elongated sensor support 70 tends to swing toward elongated reference 12 as a result of the eccentric mounting of support 70 about pivot 78. This movement may continue until a condition C is reached where switches 74 and 72 are closed and switch 76 is in an intermediate position. This condition may be used to actuate the steering mechanism to mover unit 10 toward the elongated reference 12 until a position B condition is again obtained. Displacement reference sensor 30 is also used as a means to shut down the irrigation system if movement of the mover unit 10 toward or away from elongated reference 12 exceeds a preselected value. This preselected value may be determined by the free hanging angle of eccentrically mounted sensor support 70 so that in the free hanging condition switches 72, 74 and 76 are all closed. Conversely, if mover unit 10 approaches elongated reference 12 so that the angular displacement equals that of the free hanging angle, switches 72, 74 and 76 all close and system operation will again terminate until manual correction is obtained. The above-described displacement sensor assembly, which is a part of the present invention, may be seen to be a device which is simply constructed but which is capable of providing output signals indicative of a variety of displacement conditions, including a fail-safe shut down signal. The position of mover unit 10 may be controlled within relatively narrow limits with respect to elongated reference 12. It will be noted that the system is also well adapted to tracking curves defined by elongated reference 12 as the land area is traversed. Elongated reference 12 may also be the edge of a water canal constructed to extend above the ground a distance sufficient to engage elongated support member 70. As mover unit 10 tracks along elongated reference 12, the plurality of interconnected irrigation pipe spans 16 which are interconnected between the mobile pivot 28 of inboard mover unit 10 and outboard mover unit 18 are moved along the area to be irrigated as mover units 10 and 18 are powered over the land area. It will be appreciated that the distance between inboard mover unit 10 and outboard mover unit 18 can be quite large and may approach a quarter of a mile in the largest irrigation systems. This extending pipe string may tend to lead or lag the movement of mover unit 10 so as to produce a relative rotation of extending pipe span 16 about mobile pivot 28. This relative rotation is detected by rotary transducer 50 and translated into electrical signal 52 which is functionally related to the magnitude and direction of rotation with respect to some reference position, which may conveniently be an imaginary line generally vertical to the direction of movement of mover unit 10. It is desirable to maintain this angle of rotation as small as possible in order to maximize the coverage of the irrigation system and to minimize the drag which is exerted on the irrigation pipe spans 16. In addition to relative angular movement about mobile pivot 28, the position of outboard mover unit 18 with respect to inboard mover unit 10 may vary slightly in distance as the land area is traversed. This variation in distance along the interconnected irrigation pipe span 16 introduces stresses in the pipe spans 16, which may be either in tension or compression as mover unit 18 moves either toward or away from mover unit 10, respectively. These stress forces must be measured and corrective action taken to relieve the stresses before damage to the irrigation system occurs. In one embodiment of the present invention, the stresses produce a lateral deflection of pivot 28. This lateral deflection is detected by linkage 54, as hereinabove discussed, and translated into an output signal 58 from rotary transducer 56 functionally related to the stress vector within irrigation pipe spans 16. THEORY The basic mechanism for controlling the relationship between the two mover units and, therefore, the rotation of the irrigation spans about the mobile pivot point and the stress in the irrigation spans, is to control the average speed of each mover unit. The average speed may be controlled in a variety of ways, depending on whether the drive motors are AC or DC motors. If AC motors are used, the average speed may then be varied by either varying the frequency of the power supply or varying the time period during which energy is supplied to the motors. Although both methods are considered to be within the contemplation of the present invention, the preferred embodiment discussed hereinbelow involved the selected energizing of the motors which power the inboard and outboard mover units. Referring now to FIG. 4, there may be seen a schematic of the system parameters which are monitored to control movement of the inboard 10 and outboard 18 mover units. The point of reference is pivot 28 on inboard mover unit 10. Stresses in the irrigation pipe spans result in deflection, ±D, of pivot 28. The direction of the deflection, D, defines the nature of the stress as either compression or tension. The amount of deflection, D, is functionally related to the magnitude of the stress forces in the irrigation spans 16. Rotation of the irrigation spans 16 is also measured relative to pivot 28. This angular rotation, ±θ, represents the lead or lag of the extending pipe spans with respect to mover unit 10. Hence, the entire extending irrigation system is controlled with reference to pivot 28, which reference is mobile with the controlled movement of mover unit 10 along an elongated reference. The deflection and rotation input parameters are then maintained within selected values by controlling movement of outboard mover unit 18 relative to inboard unit 10. Specifically, a duty cycle is computed for operating the motor of each mover unit to obtain the desired relative movements. If the duty cycle of the inboard mover unit 10 is chosen to be Tp, then the duty cycle of the outboard mover unit will be defined to be Te=Tp-ΔT. ΔT is calculated from the input parameters as ΔT=f[A(D)+B(θ)]=Tp-Te where A and B are constants which weight input parameters D and θ, respectively. ΔT may be maintained within preselected limits by varying the duty cycle Te of outboard mover unit 18. If necessary, the duty cycle Tp of inboard mover unit 10 can be varied to correct a large deviation. FIG. 5 shows a flow diagram of information through a control unit, hereinafter discussed as FIG. 7. The basic inputs (D, θ) are first examined. If D≠O, an angular correction is computed to return D in a correcting direction. Once D=O, the resulting angle θ is then examined. An angular correction is then generated to return θ toward a neutral reference condition. To provide the necessary angular corrections, the motor duty cycles (Te, Tp) for the respective mover units are determined for the next time interval. The motors are then energized for proportionate times to obtain the desired relative movement. FIG. 6 is a graphic representation of the various relationships which may occur between inboard mover unit 10, whose movement is depicted at time intervals denoted by Tp and outboard mover unit 18, whose movement is denoted at time intervals Te. Referring now to FIG. 6, at time To, the string of pipe spans is lagging movement of the inboard mover unit. To correct this condition over the next timing interval, the outboard mover unit is energized for a time period Te1 and the inboard mover unit is energized for a shorter time period Tp1 so as to partially correct the rotational variance by time T1. A correction is still required at time T1 so the outboard unit is again energized for a time interval Te2 and the inboard unit for a time interval Tp2, which is less than Te2. Accordingly, the selective energizing of the mover units has caused the angular discrepancy to be corrected by time T2 so that the next duty cycles, Te3 and Tp3, are equal and the units advance the same distance along the land areas without rotation about the inboard pivot point. At time T4, there may be seen a condition of tension in the irrigation pipe spans as indicated by lateral displacement of the outboard mover unit away from the inboard mover unit and detected by a lateral displacement of the inboard pivot point, as hereinabove discussed. In order to reduce the tension, the outboard unit must be caused to move toward the inboard unit and this relative movement is obtained by energizing the outboard unit for a time period Te4 and the inboard unit for a time period Tp4, which is less than Te4. Accordingly, at T5, the outboard unit has moved somewhat toward the inboard unit and thereby relieved compression in the string of irrigation pipe spans. Referring again to FIG. 6, there is depicted at time T6 a condition where the outboard mover unit has moved ahead of the inboard mover unit. This rotation is detected by the pivot rotary transducer and a control signal is provided to energize the inboard mover unit for a time period Tp6 and the outboard unit for a time period Te6, which is less than Tp6, whereby the leading condition is partially corrected by time T7. Since a deviant condition still exists at time T7, the inboard unit is again energized for a time interval longer than the outboard unit in order to obtain a corrected condition at T8. A control unit, hereinafter discussed, senses the corrected angular relationship and thereby causes the inboard and outboard units to be energized for equal time intervals Tp8 and Te8, respectively. At time T9 there is depicted a condition of compression in the irrigation pipe spans where the outboard unit has moved toward the inboard unit. Again, the lateral deflection of the pivot point is detected and an output signal is provided which energizes the inboard unit for a time interval Te9, which is less than Tp9. This results in the outboard unit slightly lagging the inboard unit and thereby tending to increase the displacement between the two mover units to reduce the compression in the irrigation pipe spans. Again, an allowable rotation is obtained in order to correct these stresses in the irrigation pipe spans. In FIG. 7 there is depicted in schematic block diagram form a control system which monitors electrical signal inputs from the transducers located on the inboard mover unit 10 and thereafter derives duty cycles for the inboard mover unit 10 and outboard mover unit 18 drive motors. In particular, the proportional motor control system 80 receives inputs relating to the condition of the extending irrigation pipe span 16 relative to pivot 28, as shown in FIG. 1. Rotation of the extending irrigation pipe section 16 about pivot 28 is detected by rotary transducer 50, which provides an output signal which is functionally related to the magnitude and direction of this rotation. The lateral deflection of the pivot 28 is functionally related to the magnitude and direction of stresses which are developed in the irrigation pipe spans and this lateral deflection is detected by a deflection linkage to cause rotation of deflection transducer 56, which produces an output signal functionally related to the stress in the irrigation pipe spans. The output signals from transducers 50 and 56 are each input to the proportional motor control system 80 through operational amplifiers 81. Each signal is input to analog multiplexer 82 which selectively presents either the rotation analog signal or the stress analog signal through operational amplifier 85 to analog-to-digital converter 86. The desired input is selected for presentation by control unit 84. Analog-to-digital converter 86 receives the output from amplifier 85, which is typically an analog voltage of zero to two volts and converts the voltage input to a digital output. The output from analog-to-digital converter 86 is presented to data bus 90 through buffers 87 which isolate the converter 86 from the data bus 90. As hereinabove discussed, each of the input signals must be weighted in order to obtain the desired overall system response. Accordingly, switches 92 and 93 are provided, which are a portion of a dual inline package whose output can be varied and thereby provide the desired constant weighting output. In addition to the primary system parameters, other input information is provided to data bus 90 for overall system control. A speed selector switch 95 is used to vary the average speeds of both the inboard and outboard mover units simultaneously. The selected average speed representation is presented from speed switch 95 through buffer 96 to data bus 90. Yet another data input is provided to monitor the condition of various switches 98 throughout the irrigation system. Switch data 98 is provided to optical isolator 99 to prevent system anamolies, such as voltage spikes resulting from static and sparks, from passing through to data bus 90. Buffer 96 interconnects the data from optical isolator 99 to data bus 90. As hereinafter explained, particular input data is selected for presentation to the data bus 90 in a programmed sequence and each input unit receives an enabling signal which directs the input to be presented to data bus 90. The input signals on data bus 90 are then presented to the computational portion of the control unit through buffer 101 to bus driver and controller 102. Bus driver 102 can transmit data signals either from the data bus 90 to a processing unit or accept signals from processing unit and transmit data back along data bus 90. Bus driver 102 also includes a control unit which provides enabling signals to various system components to obtain sequential presentation of inputs to the system and the acceptance of outputs from the system. Input data on data bus 90 is presented to central processing unit 104. Central processing unit 104 is, in essence, a mini-computer which is preprogrammed to provide a variety of processing functions. Central processing unit 104 is driven by clock 105 to obtain and evaluate data in a preselected sequence. Clock 105 also provides an output pulse train which is used to control the mover unit motors, as hereinbelow discussed. Additional system components are interconnected with central processing unit 104 to assist the processor 104 in its computations. As central processing unit 104 is clocked through its program sequence, information from memory units external to central processing unit 104 must be called for use and intermediate calculational results must be returned to memory units for temporary storage. Two different types of memory units are required to assist central processing unit 104. A first programmable, read only, memory unit 112 is utilized to instruct central processing unit 104 on the calculational steps needed to process the input data. Programmable memory units 112 are not used for intermediate storage, but store preprogrammed data and instructions for the central processing unit 104. Readable and addressable memory units 114 are provided for intermediate data storage locations. Readable memories 114 can accept data for intermediate storage and thereafter present the stored data to data bus 90 for further use in the data processing. Central processing unit 104 selectively addresses the programmable memory units 112 and addressable memory units 114 along address bus 106. In addition, a decoder 110 is connected to address bus 106 and provides a plurality of outputs which enable the various memory units to accept or transfer data along data bus 90. Other decoder units 116 are connected to address bus 106 for providing data input and output enabling signals which enable the various data input and output units to respond to the data on data bus 90. The input and output control units 116 are further selectively enabled by output signals from bus driver and controller 102 as data is being selected for input to the system and control signals are being selected for output from the system. Clock generator 105 also provides another output to pulse generator 115. Pulse generator 115 divides the high frequency output from clock 105 to obtain a train of pulses of 20 millisecond (ms) duration. The 20 ms pulse output from generator 115 is presented to central processing unit 104 along data bus 90 and acts as the basic control timing pulse chain. As hereinabove discussed, central processing unit 104 computes the duty cycle for each mover unit based on the input parameters. Central processing unit 104 then counts the 20 ms pulses from pulse generator 115 and provides an output signal to energize each mover unit until the pulse count reaches the count corresponding to the computed duty cycle. Thus, each duty cycle is computed for the next minute to a 20 ms precision. After central processing unit 104 has completed its calculations, the output motor control signals are impressed on data bus 90 and driven along by bus driver 102 through buffer 101 for presentation to output registers 118. When enabled by signals from control units 116, registers 118 accept the data presented along data bus 90. The proportional motor control signals are then presented to optical isolators 120 and then to solid state relay 122 for actual motor control. Optical isolator 120 isolates the incoming data from the actual motor control system in order to prevent spurious electrical noise from interfering with the control system. Solid state relay 122 receives the control information and energizes the motors 124 on the mover units for the duty cycle which has been calculated for each particular mover unit over a selected data interval. Typically, a one minute data interval may be used and a duty cycle of all, or a calculated portion, of that minute will be computed and used to energize the respective mover units to obtain the required system response. It will be understood that a variety of available components may be utilized to perform the functions described for each of the diagram blocks in FIG. 7. By way of example, suitable integrated circuits for the central processing unit 104, clock/generator drive 105, bus driver and controller 102, programmable read only memories 112, readable-addressable memories 114, and others are described in a catalog from Intel Corporation of September, 1975, and entitled 8080 Microcomputer Systems User's Manual. In view of the foregoing, it is apparent that there has been provided a unique method and apparatus for accomplishing irrigation of large land areas, wherein irrigation apparatus is employed that is not tethered to a physical structure, but rather moves over a land area within limits bounded by allowable error boundaries defined along an ideal intended track. Through utilization of irrigation apparatus in accordance with the present invention, it is practical to accomplish irrigation of greater tracts of land than heretofore provided. Moreover, it is not necessary to provide specific guideways for each of the various movable powers of the irrigation system in order to control lateral movement of these systems over a particular land area. By appropriate control, the irrigation system of the present invention can be caused to move laterally and to pivot in such a manner that it will automatically track along a guide structure that is not straight or is irregularly curved. Accordingly, the present invention is well adapted to attain all of the objects and advantages hereinabove set forth, together with other advantages that will become apparent and obvious from a description of the apparatus itself. It will be understood that certain combinations and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the spirit and scope of the present invention.
A linearly movable irrigation system, according to the present invention, may include a plurality of interconnected power driven irrigation spans supporting a water supply conduit, which sections are capable of moving over a land area and depositing a controlled amount of water thereon. At one extremity of the irrigation system may be provided a steerable and powered mover unit that accepts water from a water supply system and conducts it to the overhead irrigation pipe under sufficient pressure to cause proper distribution of water through sprinkler devices located along the length of the irrigation conduit. A power driven pump may be supported by the steerable mover unit in order to pressurize or provide boosting pressure for the water received from the water supply. The steerable mover unit is adapted to steerably move in proximity to an elongated reference which may be straight or curved as desired. The steerable mover unit is provided with means for sensing stresses and angular relationship of the irrigation spans relative to the steerable mover unit for providing control signals to the irrigation system that maintain stresses and angular misalignment of the system within an acceptable range. Each extremity of the irrigation system may move at different average speeds which are determined by the control signals for corrective relative movement. The extremities of the irrigation system may also move simultaneously at equal speeds or at different speeds to accomplish controlled movement during irrigation operations.
Summarize the key points of the given document.
[ "FIELD OF THE INVENTION This invention is directed generally to irrigation systems for irrigating large land areas and more specifically is directed to elongated irrigation systems that move in substantially controlled manner over a land area to accomplish irrigation of the land area.", "More specifically, the present invention is directed to an irrigation system that extracts water from an elongated water supply source, such as a ditch or water pipe, for the purpose of irrigation and which irrigation system is automatically movable and automatically steered over a land area for extended lengths of time without any requirement for significant attention by personnel.", "BACKGROUND OF THE INVENTION A valuable asset to the irrigation industry has been the development of irrigation systems that travel while sprinkling large land areas with water and require virtually no personnel attention during operation.", "Substantial elimination of the labor costs that were earlier required has greatly enhanced the commercial success of large field irrigation.", "Although many different types of irrigation systems have been developed over the years, the type of irrigation system that is most prevalent is the circular irrigation system which incorporates a plurality of sprinkler pipe sections that are each supported by a mechanism for inducing movement to the pipe sections.", "In circular irrigation systems a central pivot tower is provided that also serves as a water supply and one extremity of the irrigation system is connected thereto causing the entire irrigation system to revolve about the pivot during continuous irrigation operations.", "Although circular irrigation systems have been quite successful, it is clear that greater crop yields and lower cost irrigation would be achieved if the irrigation system were capable of irrigating rectangular land areas or other specifically shaped land areas as opposed to circular areas.", "One attempt to accomplish more rectangular irrigation through the use of circular irrigation systems is through the use of corner irrigation spray devices that are activated only during four small segments of each revolution of the irrigation system.", "Although the increase of land area irrigation through the use of irrigation guns is not insubstantial, it would nevertheless be commercially desirable to provide an irrigation system that was capable of irrigating the entirety of a large rectangular land area.", "In the past, irrigation systems have been developed for irrigation of rectangular fields, but in order to provide for proper operation of the irrigation system, it is generally deemed necessary that a plurality of tracks or guideways be provided in order to physically guide the irrigation system over the land area.", "Of the number of patented devices that have been developed with track or guideway control in mind, U.S. Pat. No. 3,608,827, to Kinkead is typically representative.", "Linearly movable irrigation systems have also been developed that do not necessitate the use of tracks or guideways such as taught by U.S. Pat. No. 3,613,703, to Stout which utilizes a guide rail 52 for reference during movement over a land area and traverses by alternate movement and pivoting of each of the ends of the system.", "In the case of the structure identified in the patent to Stout the ambulatory irrigation system is so arranged and controlled that each end of the composite line alternately can be caused to travel a predetermined distance along an arcuate path with the opposite end of the composite line temporarily being substantially at the center of curvature of the arcuate path and with the entire line thus swinging forwardly in alternate angular direction as it moves over the land area.", "More simply, one extremity of the irrigation system remains static and serves as a pivot during a portion of the movement and the sequence is then reversed causing the other extremity to remain static while the first extremity is caused to move.", "The ends of the system are not capable of simultaneous movement.", "It is considered desirable to provide a linearly movable irrigation system that does not require a track or guideway to control movement thereof such as is the case with Kinkead U.S. Pat. No. 3,608,827 and which does not cause excessive water distribution on certain of the land section such as is likely to occur when each end of the irrigation system alternately moves forward.", "U.S. Pat. No. 3,707,164 to Clemons and U.S. Pat. No. 3,974,845 to Indresaeter disclose linearly movable irrigation systems which do not require a track or fixed guideway for control of the system movement.", "Clemons teaches a method and apparatus for maintaining an irrigation system within predetermined distance from an elongated reference line.", "In one embodiment, Clemons selectively energizes adjacent tractors to provide a steering action relative to the guide and in another embodiment the tractor wheels are also turned simultaneously to move the irrigation system toward or away from the reference guide.", "Clemons also teaches maintaining the alignment between adjacent tractors by varying the flow of hydraulic fluid to hydraulic motors on the tractors for speed control.", "It should be noted that the steering control systems taught by Clemons employ control and power systems at substantially each mobile support unit.", "Further, the control systems of Clemons are actuated by only a single type of input so that the system response is corrective of only the particular input selected.", "U.S. Pat. No. 3,974,845 to Indresaeter teaches an irrigation system which is controlled by stopping and starting mover units located at extremities of the system.", "As described therein, the control system is provided with inputs functionally related to the linear displacement from the guide reference of the mover unit adjacent the guide reference and to the angular alignment of the irrigation system with respect to the guide reference.", "The correction of either linear or angular misalignment is accomplished by causing the entire irrigation system to pivot about one extremity or the other to maintain the system within preselected limits.", "Lateral displacement can be corrected only by a substantial number of correcting manuevers.", "Further, there is no input signal related to the stresses being developed in the irrigation pipe spans in order to preclude corrective action which could result in excessive system stresses.", "Accordingly, it is a primary feature of the present invention to provide a novel linearly movable irrigation system that moves in substantially linear manner over a land area and is capable of irrigating the entirety of a generally rectangular land area or irrigating a land area of an irregular shape.", "It is also a feature of the present invention to provide a novel linearly movable irrigation system whereby control of the movement of the system is accomplished by a first control system steering a mover unit adjacent an elongated reference and an independent second control system maintaining the relative rotation of the irrigation pipe spans relative to the steerable mover unit.", "It is an even further feature of the present invention to provide a novel linearly movable irrigation system that moves in linear manner over a land area and, in the event of the occurrence of predetermined misalignment of the irrigation system relative to the reference, the irrigation system is automatically self-steering to maintain its travel within a defined boundary.", "It is yet another feature of the present invention to provide a novel linearly movable irrigation system employing sensing devices for determining angular alignment of the irrigation pipe spans with respect to a pivot located on the steerable mover unit and for determining the stresses in the irrigation pipe spans and controlling the angular alignment and stress by movement relative to the steerable mover unit.", "It is also an object of the present invention to provide a novel linearly movable powered mover unit adjacent a reference such as an elongated guide surface which may be straight or curved as desired, wherein the powered mover unit is provided with a control mechanism that senses linear displacement of the mover unit relative to the reference for steerably controlling travel of the mover unit relative to the elongated reference.", "It is another object of the present invention to provide a novel linearly movable irrigation system in which angular alignment and stresses in the irrigation pipe spans are controlled by movement relative to a powered mover unit and independent from a fixed guide reference.", "It is also a feature of the present invention to provide a novel linearly movable irrigation system wherein a plurality of individually supported and driven sections are incorporated into an elongated irrigation system and wherein movement of each of the sections is controlled by its angular relationship with an adjacent irrigation section, such angular relationship control overridden under certain circumstances by control signals received from a power and control portion of the irrigation system.", "SUMMARY OF THE INVENTION The present invention is directed to a linearly movable steerable irrigation system that is adapted to move in substantially linear manner for irrigation of a large generally rectangular land area.", "The irrigation system is adapted to move automatically in response to its position relative to an elongated reference such as an elongated straight or curved guide surface, guide rail, guide line or guide beam during irrigation operations and in response to the angular alignment and stresses of irrigation pipe spans relative to a powered mover unit adjacent the elongated reference.", "Sensing apparatus carried by a powered mover unit of the irrigation system is capable of sensing both linear displacement of the mover unit relative to the elongated reference and the angular alignment and stresses of the irrigation pipe spans relative to the powered mover unit and automatically self-correcting the direction of movement in the event the irrigation system has moved beyond allowable limits of linear displacement, angular misalignment or system stresses.", "The irrigation system includes a powered mover unit that is provided at one extremity thereof or intermediate the extremities of the system and which will typically be directly connected to linear displacement, angular misalignment, and system stress sensors that determine relative positioning of the irrigation system.", "To the powered mover unit may be connected a plurality of irrigation sections each comprising an irrigation span that is supported by any suitable mobile support such as wheels, tracks, ambulatory mechanisms, etc.", "that is capable of accomplishing movement of the irrigation system over the land area.", "An elongated irrigation conduit being a composite of a number of interconnected sections of irrigation pipe will be supported by the spans above the land area and will cause distribution of water on the land area by means of sprinkler devices carried by the various sections of water supply pipe.", "Each of the self-driven sections or spans of the irrigation system may be controllably activated and deactivated by the angular relationship thereof to other spans or sections to accomplish controlled movement of the spans of the irrigation system.", "Conventional angular detection sensors may be employed to detect angular misalignment between the respective sections of the irrigation system.", "When such angular misalignment reaches a predetermined value, the drive mechanisms controlled by the angular detecting device for each section will be energized causing the drive means to impart driving movement to that particular section of the irrigation system.", "Such driving will continue until sufficient movement of that section has occurred to change the angular relation detected by the angular detecting device to another predetermined value, at which time the drive mechanism for that irrigation section will be de-energized.", "For accomplishing steering control responsive to signals received by the powered mover unit from the linear displacement sensors contacting the elongated reference, steering pistons on a steerable powered mover unit are actuated to rotate the mobile support, such as wheels, and maintain the steerable powered mover unit within preselected displacement limits of the elongated reference.", "Hence, continuous irrigation system movement can be maintained when minor steering corrections are being made and the system is enabled to promptly respond to correcting signals.", "Extending from the steerable mover unit may be a plurality of irrigation pipe spans and a powered mover unit connected substantially at the extremity of the connected pipe spans.", "The extending pipe spans may be pivotally connected to the steerable mover unit to define a reference for measuring angular alignment of the irrigation spans with the steerable mover unit and for measuring stresses within the pipe spans as a function of the reference pivot.", "The angular alignment and stresses of the irrigation pipe spans are maintained within preselected limits by varying the average speeds of the steerable mover unit and the outboard mover unit to obtain rotation of the extending pipe spans relative to the pivot.", "For example, mover unit average speed may be varied by controlling the duration for energizing the mover unit motor over a selected time interval, i.e. controlling the duty cycle of the motor.", "Varying the duty cycle of the inboard and outboard mover unit motors will produce relative pivotal movement of the outboard unit about the inboard unit.", "When this relative pivotal movement has continued sufficiently to satisfy the requirements of the control signal, another control signal will be provided causing both extremities of the irrigation system to move at the same or different average speed, causing the entire irrigation system to move in substantially linear or controllably turning manner across the land area.", "Upon movement of the irrigation system sufficiently to traverse control boundaries defined by the stress and angular misalignment sensors, another control signal will be issued, causing the opposite extremity of the irrigation system to remain static or to be controllably slowed while the other extremity of the irrigation system is allowed to continue moving.", "The resulting effect is a relative pivoting of the entire irrigation system about the steerable mover unit.", "In other words, the irrigation system will move across the land area in substantially linear manner unless for some reason it should become over-stressed or angularly misaligned relative to the steerable mover unit.", "This can be caused by traversing of the irrigation system over undulations in the terrain or by other than straight line positioning of the reference such as might occur if the reference is designed to cause tracking of the irrigation system to irrigate an oval land area.", "The present invention is also directed to the method of accomplishing irrigation of land areas, wherein the elongated irrigation system, capable of movement across a land area in substantially linear manner, is also capable of being steered automatically so as to correct any lateral displacement from an elongated reference.", "The irrigation apparatus, under the novel method of controlling the operation thereof, is capable of irrigating generally rectangular land areas and because of its automatic steering capability, is also capable of traversing land areas that are of irregular configuration.", "Each extremity of the irrigation system is capable of independent movement responsive to control signals received from a control facility and may move at different speeds, stop, or move at the same speed as the opposite extremity of the irrigation system.", "Also, the power and control facility for the irrigation apparatus may be located intermediate the extremities of the irrigation system or at either extremity thereof within the teachings of the present invention.", "Water supply for the irrigation system may take the form of an elongated ditch from which water is extracted by suction or it may take the form of an elongated closed water supply system such as a pipe having a plurality of water supply connections that are automatically received and released in such manner as to provide substantially continuous water flow as the irrigation system traverses its designated path of travel.", "BRIEF DESCRIPTION OF THE DRAWINGS So that the manner in which the above-recited features, advantages and objects of the present invention as well as others which will become apparent, are obtained and can be understood in detail, more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings, which drawings form a part of this specification.", "The present invention, both as to its organization and manner of operation may best be understood by way of illustration and example of certain preferred embodiments when taken in conjunction with the accompanying drawings.", "IN THE DRAWINGS FIG. 1 is a plan view partially in schematic form illustrating a linearly movable irrigation system that is constructed in accordance with the principles of the present invention.", "FIG. 2 is a plan view of a motorized steerable mover unit and illustrating the position of the various sensors on the mover unit frame.", "FIG. 3 is an elevation view illustrating one embodiment of a displacement sensor for determining the position of the mover unit frame relative to an elongated reference.", "FIG. 4 is a schematic illustration of control system input parameters.", "FIG. 5 is a schematic illustration of the basic control system logic.", "FIG. 6 is a graphic representation of the track of controlled movement of the irrigation system in response to various input signals.", "FIG. 7 is a block diagram schematic of a control unit for evaluating input information and determining an appropriate response in accordance with a preferred embodiment of the present invention.", "DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings and first to FIG. 1, there is depicted a self-driven irrigation system of the type that is adapted to move across a large land area to be irrigated and to follow elongated reference while controlling an extending string of irrigation pipe spans to maintain the stresses in the irrigation pipe spans and the rotation of the elongated string of pipe within predetermined values.", "As shown in FIG. 1, the irrigation system incorporates a motorized steerable mover unit depicted generally at 10.", "On the mover unit 10 may be provided an engine, pump, and generator unit 22 providing mechanical and electrical power for operation of the irrigation system.", "Mover unit 10 is in communication with a water supply source 14 and may extract water from the water supply and transmit it under pressure to a plurality of irrigation spans 16 from which it is evenly distributed on the land surface by a plurality of conventional sprinkler devices that are carried by the irrigation pipe spans.", "Extending from the mover unit 10 are a plurality of irrigation sections or spans 16 that comprise a structural framework for support of each of the various sections of irrigation water supply pipe that are interconnected to form the irrigation system.", "Each of these spans or sections 16 may be supported by a mobile base 17, the respective mobile bases 17 being provided with wheels, tracks, ambulatory devices, etc.", "in order to provide the mobility that causes the irrigation system to traverse the land area being irrigated.", "An outboard mover unit 18 is provided preferably adjacent the end of the irrigation span removed from water supply 14.", "Mover unit 18 may be provided with an individual power means which is controlled so as to permit rotation of the plurality of interconnected irrigation pipe spans 16 with respect to the steerable mover unit 10, as will be hereinafter explained in more detail.", "For controlling the track of the irrigation system over the land area, an elongated reference 12 may be provided.", "The elongated reference may take many suitable forms that enable position sensing devices to react with the reference and steer the steerable mover unit to maintain a predetermined distance between the steerable mover unit and the elongated reference 12.", "For example, the reference may be a guide rail supported above the ground on posts, it may take the form of a supported guide wire and it may also take the form of a guide surface formed by the water supply, such as an external wall of a concrete lined ditch that is partially embedded in the ground or supported on the surface of the land area.", "The reference, where a straight line reference is desired, may take the form of a laser beam or other suitable beam that may be appropriately sensed.", "If the novel sensing device, hereinafter described, which is subject of the present invention is employed, a supported guide wire is the preferred form of the elongated reference 12.", "While the reference 12 is shown to be in the form of a straight line in FIG. 1, it is not intended to limit the present invention solely to use under conditions where the reference takes the form of the straight line.", "The reference 12 may be curved in any suitable form that is appropriate for guiding the track of the irrigation system about the land area to be irrigated.", "Referring now to FIG. 2, there may be seen a plan view of steerable mover unit 10.", "A frame 34 is provided which is mounted on a suitable mobile support for traversing a terrain suitable for irrigation, which mobile support may conveniently take the form of wheels 38 supported on axles 36 which are rotatably mounted on frame 34.", "Wheels 38 may be rotated to steer mover unit 10 either toward or away from elongated reference 12 so as to maintain a predetermined distance between the mover unit 10 and elongated reference 12.", "Sensor units 30 may be mounted on sensor support arms 40 which are connected to the wheel axles 36 which are nearest the elongated reference 12.", "In operation, the leading sensor 30 at each wheel location is selected to provide an input signal, the leading sensor being determined by the direction of travel of mover unit 10.", "Electrical output lines 32 from each sensor 30, conveniently carried in cable bundle 33 mounted on frame 34, provide a plurality of output signals from each sensor 30 as inputs to control unit 24.", "Electrical outputs 32 from sensors 30 are used to control the steering mechanisms 44 and 42 and control the position of mover unit 10 relative to elongated reference 12.", "Tie rods 37 connect the pair of wheel axles 36 at each end of mover unit 10 so that simultaneous movement of each pair of wheels 38 will occur.", "Steering actuators 42 and 44 may conveniently take the form of hydraulically-actuated pistons which are actuated through hydraulic output lines 45, which may conveniently be interconnected with the output of the water pump (not shown) contained in engine section 22.", "Actuators 42 initiate movement of mover unit 10 away from elongated reference 12, whereas actuators 44 initiate movement toward elongated reference 12.", "In a preferred embodiment, a sensor 30 will activate the steering mechanism for the pair of wheels 33 on which it is mounted.", "In this manner, each end of mover unit 10 will move toward or away from elongated reference 12 as determined from the outputs from sensors 30.", "A particular displacement sensor contemplated as part of the present invention may be seen by reference to FIG. 3, as more particularly hereinafter discussed.", "In FIG. 2 there may also be seen engine section 22 which is depicted in block form.", "Engine section 22 may contain a motor powered by conventional fuel sources such as gasoline, butane, diesel fuel, etc.", "and interconnected with a conventional generator for supplying electrical energy to power mover unit 10 and other mover units interconnected therewith.", "The engine may be conventionally connected to a pump via a power take-off unit to provide a pressurized supply of water to the irrigation pipe spans for suitable distribution through sprinklers to the land area.", "A portion of the pump output may be diverted through hydraulic lines 45 to activate steering actuators 42 and 44, as hereinabove discussed.", "The output from the electrical generator is supplied to electrical motors for powering the mover units, and may be controlled as hereinbelow discussed to maintain movement of the irrigation system across the land area.", "Referring again to FIG. 2, there may be seen a pressurized water supply pipe 26, connected to the output of the pump and engine section 22 and suitably supported on frame 34 by a tower-like support structure (not shown).", "Water pipe 26 is connected to pivot section 28 and thereafter interconnected with irrigation pipe span 16.", "Pivot 28 defines a reference point with respect to the plurality of irrigation pipe spans 16 which extend outwardly from pivot 28 and which interconnect with mover unit 18, as depicted in FIG. 1. As hereinafter described, the rotation of irrigation pipe spans 16 about pivot 28 is measured by rotary transducer 50 which provides an output signal 52 which is functionally related to the amount of angular rotation of irrigation pipe span 16 about pivot 28.", "Pivot 28 is mounted on frame 34 so that pivot 28 may be deflected along the line of the interconnected irrigation pipe span 16.", "The direction and amount of deflection of pivot 28 is functionally related to the tension and compression stress forces which occur in the string of interconnected irrigation pipe spans 16.", "Control of these stress forces is important to maintaining control of the irrigation system, as more fully discussed hereinbelow.", "The deflection of pivot 28 is detected by deflection linkage 54 and translated into a rotary movement which is detected by deflection rotary transducer 56.", "Deflection transducer 56 thereby provides an electrical output signal 58 which is functionally related to the magnitude and direction of the stresses which are obtained in the interconnected irrigation pipe spans 16.", "The extending irrigation pipe spans 16 must be maintained in a relationship to adjacent pipe spans to permit movement about pivot 28 to functionally represent the condition of the entire pipe string.", "Such a relationship is maintained by sensing the angular relationship between adjacent pipe spans and controlling the intermediate mobile bases 17, as shown in FIG. 1, to correct misalignment on a span-to-span basis.", "The intermediate mobile bases 17 are normally energized and then controllably de-energized to maintain each span 16 within a preselected angular relationship with adjacent spans.", "The entire extending pipe string is thereby maintained as a substantially straight line so that pivot 28 may be used as an appropriate reference.", "The outputs 52 and 58 from pivot rotation transducer 50 and deflection transducer 56, respectively, are provided as inputs to control unit 24 to obtain a first output 60 to control the motor of inboard mover unit 10 and a second output 62 which controls the motor of outboard mover unit 18 which is displaced from mover unit 10.", "It is readily apparent from the foregoing discussion that, according to the present invention, movement of the irrigation system in a controlled fashion is accomplished by first steering mover unit 10 with respect to an elongated reference 12 to independently establish the track of mover unit 10 across the land area which is to be irrigated.", "The interconnected plurality of irrigation pipe spans 16 is then maintained in a controlled relationship with respect to mover unit 10 by controlling mover unit 18 which may conveniently be located near the end of the interconnected spans of irrigation pipe.", "As fully discussed hereinbelow for FIGS. 4 and 5, the relationship between the extending irrigation pipe spans and the steerable mover unit 10 permits the string of irrigation pipe to be maintained in a generally perpendicualr relationship with respect to elongated reference 12 and yet allow some variation in its angular relationship to provide corrective movement which relieves stresses occurring along the interconnected pipe spans.", "Referring now to FIG. 3, there is shown displacement sensor 30 according to one embodiment of the present invention.", "Displacement sensor 30 includes an elongated sensor support member 70 which is mounted on mover unit 10 by pivotally connecting elongated sensor support member 70 to displacement sensor support 40.", "Elongated sensor support 70 is eccentrically mounted at pivot 78 to displacement sensor support frame 40.", "The eccentric location of pivot 78 is provided so that elongated sensor support 70 will assume a preselected angle with respect to the vertical when in a free hanging condition.", "As explained below, the free hanging angle is a limit which determines a maximum displacement of mover unit 10 from elongated reference 12.", "As mover unit 10 traverses the land area to be irrigated, sensor support member 70 contacts elongated reference 12 and rotates about pivot 78 as mover unit 10 moves variably in relationship to its displacement from elongated reference 12.", "A plurality of switches are mounted on elongated reference 70 which are selectively energized to detect the angular position of elongated sensor support 70.", "As depicted in FIG. 3, switches 72, 74 and 76 illustrate the relationship of switch outputs to various angular conditions.", "Position A of FIG. 3 depicts movement of mover unit 10 toward elongated reference 12.", "Switches 76 and 74, which may conveniently take the form of mercury limit switches in which contact is completed when mercury pools in one end or the other, are rotated so as to complete the circuits connected therewith (not shown).", "Switch 72 has moved to a level position where the mercury is pooled in an intermediate location so that contact is not made at either end of switch 72.", "The output from switches 76 and 74 may be used to activate the steering mechanism as hereinabove discussed to steer mover unit 10 away from elongated reference 12 until elongated sensor support 70 reaches position B. At condition B, sensors 76 and 72 now have completed electrical contacts and sensor 74 is in the intermediate condition.", "The output from the position B condition may be used to activate the steering mechanism to return the wheels to a neutral position.", "If mover unit 10 begins to drift away from elongated reference 12, elongated sensor support 70 tends to swing toward elongated reference 12 as a result of the eccentric mounting of support 70 about pivot 78.", "This movement may continue until a condition C is reached where switches 74 and 72 are closed and switch 76 is in an intermediate position.", "This condition may be used to actuate the steering mechanism to mover unit 10 toward the elongated reference 12 until a position B condition is again obtained.", "Displacement reference sensor 30 is also used as a means to shut down the irrigation system if movement of the mover unit 10 toward or away from elongated reference 12 exceeds a preselected value.", "This preselected value may be determined by the free hanging angle of eccentrically mounted sensor support 70 so that in the free hanging condition switches 72, 74 and 76 are all closed.", "Conversely, if mover unit 10 approaches elongated reference 12 so that the angular displacement equals that of the free hanging angle, switches 72, 74 and 76 all close and system operation will again terminate until manual correction is obtained.", "The above-described displacement sensor assembly, which is a part of the present invention, may be seen to be a device which is simply constructed but which is capable of providing output signals indicative of a variety of displacement conditions, including a fail-safe shut down signal.", "The position of mover unit 10 may be controlled within relatively narrow limits with respect to elongated reference 12.", "It will be noted that the system is also well adapted to tracking curves defined by elongated reference 12 as the land area is traversed.", "Elongated reference 12 may also be the edge of a water canal constructed to extend above the ground a distance sufficient to engage elongated support member 70.", "As mover unit 10 tracks along elongated reference 12, the plurality of interconnected irrigation pipe spans 16 which are interconnected between the mobile pivot 28 of inboard mover unit 10 and outboard mover unit 18 are moved along the area to be irrigated as mover units 10 and 18 are powered over the land area.", "It will be appreciated that the distance between inboard mover unit 10 and outboard mover unit 18 can be quite large and may approach a quarter of a mile in the largest irrigation systems.", "This extending pipe string may tend to lead or lag the movement of mover unit 10 so as to produce a relative rotation of extending pipe span 16 about mobile pivot 28.", "This relative rotation is detected by rotary transducer 50 and translated into electrical signal 52 which is functionally related to the magnitude and direction of rotation with respect to some reference position, which may conveniently be an imaginary line generally vertical to the direction of movement of mover unit 10.", "It is desirable to maintain this angle of rotation as small as possible in order to maximize the coverage of the irrigation system and to minimize the drag which is exerted on the irrigation pipe spans 16.", "In addition to relative angular movement about mobile pivot 28, the position of outboard mover unit 18 with respect to inboard mover unit 10 may vary slightly in distance as the land area is traversed.", "This variation in distance along the interconnected irrigation pipe span 16 introduces stresses in the pipe spans 16, which may be either in tension or compression as mover unit 18 moves either toward or away from mover unit 10, respectively.", "These stress forces must be measured and corrective action taken to relieve the stresses before damage to the irrigation system occurs.", "In one embodiment of the present invention, the stresses produce a lateral deflection of pivot 28.", "This lateral deflection is detected by linkage 54, as hereinabove discussed, and translated into an output signal 58 from rotary transducer 56 functionally related to the stress vector within irrigation pipe spans 16.", "THEORY The basic mechanism for controlling the relationship between the two mover units and, therefore, the rotation of the irrigation spans about the mobile pivot point and the stress in the irrigation spans, is to control the average speed of each mover unit.", "The average speed may be controlled in a variety of ways, depending on whether the drive motors are AC or DC motors.", "If AC motors are used, the average speed may then be varied by either varying the frequency of the power supply or varying the time period during which energy is supplied to the motors.", "Although both methods are considered to be within the contemplation of the present invention, the preferred embodiment discussed hereinbelow involved the selected energizing of the motors which power the inboard and outboard mover units.", "Referring now to FIG. 4, there may be seen a schematic of the system parameters which are monitored to control movement of the inboard 10 and outboard 18 mover units.", "The point of reference is pivot 28 on inboard mover unit 10.", "Stresses in the irrigation pipe spans result in deflection, ±D, of pivot 28.", "The direction of the deflection, D, defines the nature of the stress as either compression or tension.", "The amount of deflection, D, is functionally related to the magnitude of the stress forces in the irrigation spans 16.", "Rotation of the irrigation spans 16 is also measured relative to pivot 28.", "This angular rotation, ±θ, represents the lead or lag of the extending pipe spans with respect to mover unit 10.", "Hence, the entire extending irrigation system is controlled with reference to pivot 28, which reference is mobile with the controlled movement of mover unit 10 along an elongated reference.", "The deflection and rotation input parameters are then maintained within selected values by controlling movement of outboard mover unit 18 relative to inboard unit 10.", "Specifically, a duty cycle is computed for operating the motor of each mover unit to obtain the desired relative movements.", "If the duty cycle of the inboard mover unit 10 is chosen to be Tp, then the duty cycle of the outboard mover unit will be defined to be Te=Tp-ΔT.", "ΔT is calculated from the input parameters as ΔT=f[A(D)+B(θ)]=Tp-Te where A and B are constants which weight input parameters D and θ, respectively.", "ΔT may be maintained within preselected limits by varying the duty cycle Te of outboard mover unit 18.", "If necessary, the duty cycle Tp of inboard mover unit 10 can be varied to correct a large deviation.", "FIG. 5 shows a flow diagram of information through a control unit, hereinafter discussed as FIG. 7. The basic inputs (D, θ) are first examined.", "If D≠O, an angular correction is computed to return D in a correcting direction.", "Once D=O, the resulting angle θ is then examined.", "An angular correction is then generated to return θ toward a neutral reference condition.", "To provide the necessary angular corrections, the motor duty cycles (Te, Tp) for the respective mover units are determined for the next time interval.", "The motors are then energized for proportionate times to obtain the desired relative movement.", "FIG. 6 is a graphic representation of the various relationships which may occur between inboard mover unit 10, whose movement is depicted at time intervals denoted by Tp and outboard mover unit 18, whose movement is denoted at time intervals Te.", "Referring now to FIG. 6, at time To, the string of pipe spans is lagging movement of the inboard mover unit.", "To correct this condition over the next timing interval, the outboard mover unit is energized for a time period Te1 and the inboard mover unit is energized for a shorter time period Tp1 so as to partially correct the rotational variance by time T1.", "A correction is still required at time T1 so the outboard unit is again energized for a time interval Te2 and the inboard unit for a time interval Tp2, which is less than Te2.", "Accordingly, the selective energizing of the mover units has caused the angular discrepancy to be corrected by time T2 so that the next duty cycles, Te3 and Tp3, are equal and the units advance the same distance along the land areas without rotation about the inboard pivot point.", "At time T4, there may be seen a condition of tension in the irrigation pipe spans as indicated by lateral displacement of the outboard mover unit away from the inboard mover unit and detected by a lateral displacement of the inboard pivot point, as hereinabove discussed.", "In order to reduce the tension, the outboard unit must be caused to move toward the inboard unit and this relative movement is obtained by energizing the outboard unit for a time period Te4 and the inboard unit for a time period Tp4, which is less than Te4.", "Accordingly, at T5, the outboard unit has moved somewhat toward the inboard unit and thereby relieved compression in the string of irrigation pipe spans.", "Referring again to FIG. 6, there is depicted at time T6 a condition where the outboard mover unit has moved ahead of the inboard mover unit.", "This rotation is detected by the pivot rotary transducer and a control signal is provided to energize the inboard mover unit for a time period Tp6 and the outboard unit for a time period Te6, which is less than Tp6, whereby the leading condition is partially corrected by time T7.", "Since a deviant condition still exists at time T7, the inboard unit is again energized for a time interval longer than the outboard unit in order to obtain a corrected condition at T8.", "A control unit, hereinafter discussed, senses the corrected angular relationship and thereby causes the inboard and outboard units to be energized for equal time intervals Tp8 and Te8, respectively.", "At time T9 there is depicted a condition of compression in the irrigation pipe spans where the outboard unit has moved toward the inboard unit.", "Again, the lateral deflection of the pivot point is detected and an output signal is provided which energizes the inboard unit for a time interval Te9, which is less than Tp9.", "This results in the outboard unit slightly lagging the inboard unit and thereby tending to increase the displacement between the two mover units to reduce the compression in the irrigation pipe spans.", "Again, an allowable rotation is obtained in order to correct these stresses in the irrigation pipe spans.", "In FIG. 7 there is depicted in schematic block diagram form a control system which monitors electrical signal inputs from the transducers located on the inboard mover unit 10 and thereafter derives duty cycles for the inboard mover unit 10 and outboard mover unit 18 drive motors.", "In particular, the proportional motor control system 80 receives inputs relating to the condition of the extending irrigation pipe span 16 relative to pivot 28, as shown in FIG. 1. Rotation of the extending irrigation pipe section 16 about pivot 28 is detected by rotary transducer 50, which provides an output signal which is functionally related to the magnitude and direction of this rotation.", "The lateral deflection of the pivot 28 is functionally related to the magnitude and direction of stresses which are developed in the irrigation pipe spans and this lateral deflection is detected by a deflection linkage to cause rotation of deflection transducer 56, which produces an output signal functionally related to the stress in the irrigation pipe spans.", "The output signals from transducers 50 and 56 are each input to the proportional motor control system 80 through operational amplifiers 81.", "Each signal is input to analog multiplexer 82 which selectively presents either the rotation analog signal or the stress analog signal through operational amplifier 85 to analog-to-digital converter 86.", "The desired input is selected for presentation by control unit 84.", "Analog-to-digital converter 86 receives the output from amplifier 85, which is typically an analog voltage of zero to two volts and converts the voltage input to a digital output.", "The output from analog-to-digital converter 86 is presented to data bus 90 through buffers 87 which isolate the converter 86 from the data bus 90.", "As hereinabove discussed, each of the input signals must be weighted in order to obtain the desired overall system response.", "Accordingly, switches 92 and 93 are provided, which are a portion of a dual inline package whose output can be varied and thereby provide the desired constant weighting output.", "In addition to the primary system parameters, other input information is provided to data bus 90 for overall system control.", "A speed selector switch 95 is used to vary the average speeds of both the inboard and outboard mover units simultaneously.", "The selected average speed representation is presented from speed switch 95 through buffer 96 to data bus 90.", "Yet another data input is provided to monitor the condition of various switches 98 throughout the irrigation system.", "Switch data 98 is provided to optical isolator 99 to prevent system anamolies, such as voltage spikes resulting from static and sparks, from passing through to data bus 90.", "Buffer 96 interconnects the data from optical isolator 99 to data bus 90.", "As hereinafter explained, particular input data is selected for presentation to the data bus 90 in a programmed sequence and each input unit receives an enabling signal which directs the input to be presented to data bus 90.", "The input signals on data bus 90 are then presented to the computational portion of the control unit through buffer 101 to bus driver and controller 102.", "Bus driver 102 can transmit data signals either from the data bus 90 to a processing unit or accept signals from processing unit and transmit data back along data bus 90.", "Bus driver 102 also includes a control unit which provides enabling signals to various system components to obtain sequential presentation of inputs to the system and the acceptance of outputs from the system.", "Input data on data bus 90 is presented to central processing unit 104.", "Central processing unit 104 is, in essence, a mini-computer which is preprogrammed to provide a variety of processing functions.", "Central processing unit 104 is driven by clock 105 to obtain and evaluate data in a preselected sequence.", "Clock 105 also provides an output pulse train which is used to control the mover unit motors, as hereinbelow discussed.", "Additional system components are interconnected with central processing unit 104 to assist the processor 104 in its computations.", "As central processing unit 104 is clocked through its program sequence, information from memory units external to central processing unit 104 must be called for use and intermediate calculational results must be returned to memory units for temporary storage.", "Two different types of memory units are required to assist central processing unit 104.", "A first programmable, read only, memory unit 112 is utilized to instruct central processing unit 104 on the calculational steps needed to process the input data.", "Programmable memory units 112 are not used for intermediate storage, but store preprogrammed data and instructions for the central processing unit 104.", "Readable and addressable memory units 114 are provided for intermediate data storage locations.", "Readable memories 114 can accept data for intermediate storage and thereafter present the stored data to data bus 90 for further use in the data processing.", "Central processing unit 104 selectively addresses the programmable memory units 112 and addressable memory units 114 along address bus 106.", "In addition, a decoder 110 is connected to address bus 106 and provides a plurality of outputs which enable the various memory units to accept or transfer data along data bus 90.", "Other decoder units 116 are connected to address bus 106 for providing data input and output enabling signals which enable the various data input and output units to respond to the data on data bus 90.", "The input and output control units 116 are further selectively enabled by output signals from bus driver and controller 102 as data is being selected for input to the system and control signals are being selected for output from the system.", "Clock generator 105 also provides another output to pulse generator 115.", "Pulse generator 115 divides the high frequency output from clock 105 to obtain a train of pulses of 20 millisecond (ms) duration.", "The 20 ms pulse output from generator 115 is presented to central processing unit 104 along data bus 90 and acts as the basic control timing pulse chain.", "As hereinabove discussed, central processing unit 104 computes the duty cycle for each mover unit based on the input parameters.", "Central processing unit 104 then counts the 20 ms pulses from pulse generator 115 and provides an output signal to energize each mover unit until the pulse count reaches the count corresponding to the computed duty cycle.", "Thus, each duty cycle is computed for the next minute to a 20 ms precision.", "After central processing unit 104 has completed its calculations, the output motor control signals are impressed on data bus 90 and driven along by bus driver 102 through buffer 101 for presentation to output registers 118.", "When enabled by signals from control units 116, registers 118 accept the data presented along data bus 90.", "The proportional motor control signals are then presented to optical isolators 120 and then to solid state relay 122 for actual motor control.", "Optical isolator 120 isolates the incoming data from the actual motor control system in order to prevent spurious electrical noise from interfering with the control system.", "Solid state relay 122 receives the control information and energizes the motors 124 on the mover units for the duty cycle which has been calculated for each particular mover unit over a selected data interval.", "Typically, a one minute data interval may be used and a duty cycle of all, or a calculated portion, of that minute will be computed and used to energize the respective mover units to obtain the required system response.", "It will be understood that a variety of available components may be utilized to perform the functions described for each of the diagram blocks in FIG. 7. By way of example, suitable integrated circuits for the central processing unit 104, clock/generator drive 105, bus driver and controller 102, programmable read only memories 112, readable-addressable memories 114, and others are described in a catalog from Intel Corporation of September, 1975, and entitled 8080 Microcomputer Systems User's Manual.", "In view of the foregoing, it is apparent that there has been provided a unique method and apparatus for accomplishing irrigation of large land areas, wherein irrigation apparatus is employed that is not tethered to a physical structure, but rather moves over a land area within limits bounded by allowable error boundaries defined along an ideal intended track.", "Through utilization of irrigation apparatus in accordance with the present invention, it is practical to accomplish irrigation of greater tracts of land than heretofore provided.", "Moreover, it is not necessary to provide specific guideways for each of the various movable powers of the irrigation system in order to control lateral movement of these systems over a particular land area.", "By appropriate control, the irrigation system of the present invention can be caused to move laterally and to pivot in such a manner that it will automatically track along a guide structure that is not straight or is irregularly curved.", "Accordingly, the present invention is well adapted to attain all of the objects and advantages hereinabove set forth, together with other advantages that will become apparent and obvious from a description of the apparatus itself.", "It will be understood that certain combinations and subcombinations are of utility and may be employed without reference to other features and subcombinations.", "This is contemplated by and is within the spirit and scope of the present invention." ]
TECHNICAL FIELD The present invention relates to a planar light source device in which a plurality of light sources are disposed two-dimensionally in a rectangular region on a mounting surface and to a liquid crystal display device that includes the planar light source device. BACKGROUND ART Conventionally, as a planar light source device that illuminates a liquid crystal panel, a so-called illumination device of direct type, which is disposed right under a rear surface of the liquid crystal panel, is proposed. As a light source of such an illumination device, it is possible to use a tube-like light source (e.g., cold-cathode tube lamp) as in patent documents 1 to 3 or use a point light source (e.g., LED (light emitting diode) as in a patent document 4. Especially, an LED is advantageous in longevity and low power consumption, and in recent years, many LEDs are used as light sources of illumination devices. In the meantime, when humans watch a screen of a liquid crystal panel, they watch more carefully the screen center than the screen peripheral. Because of this, in a case of using LEDs as the light source, even if the disposition density of the LEDs is made low at the peripheral portion, visual brightness unevenness is not conspicuous. As described above, by partially changing the disposition density of the LEDs, it is possible to secure the brightness of a necessary region (screen center) and achieve low cost by reducing the number of LEDs mounted. When changing partially the disposition density of the LEDs, in the patent document 4, as shown in FIG. 25 , LED boards 102 mounting a plurality of LEDs 101 are disposed in parallel, and disposition intervals of the LED boards 102 are partially changed. Specifically, in a central portion Rc in an arrangement direction of the LED boards 102 , the interval of neighboring LED boards 102 is made narrow, while in an outside peripheral portion Rp with respect to the central portion Rc in the arrangement direction of the LED boards 102 , the interval of neighboring LED boards 102 is made wide. As described above, it is conceivable that by adjusting the interval of the LED boards 102 to change partially the disposition density of the LEDs, it is also possible to easily deal with a size change of an illumination device 100 . Besides, in the illumination device in the patent document 4, a reflection sheet 103 is disposed on a bottom plate (mounting surface) of a backlight chassis where the LED board 102 is mounted. The reflection sheet 103 has an opening portion for exposing the LED 101 and is disposed on the bottom plate to cover the LED board 102 . An edge portion 103 a of the reflection sheet 103 rises obliquely from the bottom plate. As described above, by disposing the reflection sheet 103 , even if the LED 101 is not disposed on a peripheral portion of the bottom plate, it is possible to illuminate a screen peripheral portion of a liquid crystal panel by means of light that is emitted from the LED 101 and reflected by the edge portion 103 a of the reflection sheet 103 . Accordingly, it is possible to achieve low cost by further reducing the number of LEDs 101 mounted. CITATION LIST Patent Literature PLT1: International Publication No. 2009/004840 pamphlet (see claim 1, FIG. 5 and the like). PLT2: International Publication No. 2009/004841 pamphlet (see claim 1, FIG. 5 and the like). PLT3: International Publication No. 2010/146920 pamphlet (see claim 1, FIG. 11, FIG. 12 and the like). PLT4: International Publication No. 2010/146921 pamphlet (see claims 1, 2, paragraphs [0005], [0008], [0035], [0036], FIG. 7 and the like). SUMMARY OF INVENTION Technical Problem In the meantime, in FIG. 25 , the LEDs 101 are disposed in a region on the bottom plate where the edge portion 103 a of the reflection sheet 103 does not exist, that is, a rectangular region of V1 (cm) height×H1 (cm) width. On the other hand, the bottom plate of the back chassis has a size of V2 (cm) height×H2 (cm) width, where V1<V2, and H1<H2. As describe above, because of the reduction in the number of LEDs 101 mounted, if the size (V1×H1) of the disposition region for the LEDs 101 becomes smaller than the size (V2×H2) of the bottom plate and the disposition density of the LEDs 101 in the disposition region becomes lower in the peripheral portion Rp than in the central portion Rc, the light has difficulty in reaching four corners of the screen of the liquid crystal panel from LEDs 101 a to 101 d at four corners of the disposition region. As a result of this, as shown in FIG. 26 , a phenomenon easily occurs, in which the brightness in four-corner regions 201 a to 201 d of the screen of the liquid crystal panel declines. The present invention has been made to solve the above problems, and it is an object of the present invention to provide: a planar light source device that is able to alleviate the brightness declining at the four corners of an illumination region of an illumination target even in a structure in which a plurality of light sources are disposed such that the disposition density becomes lower in a peripheral portion than in a central portion in a small region that is smaller than a size of a bottom plate; and a liquid crystal display device that includes the planar light source device. Solution to Problem A planar light source device according to an aspect of the present invention comprises: a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, wherein the rectangular region has, at four corners thereof, corner regions where at least one of the light sources is disposed, and the light source located in each of the corner regions is disposed such that a central axis thereof inclines from a direction perpendicular to the mounting surface toward an outer peripheral side of the rectangular region. A planar light source device according to another aspect of the present invention comprises: a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, the planar light source device further comprising a diffusion lens that is disposed correspondingly to each of the plurality of light sources and diffuses light emitted from the light source, wherein the rectangular region has, at four corners thereof, corner regions where at least one of the light sources is disposed, and the diffusion lens corresponding to the light source located in each of the corner regions is disposed such that a central axis thereof is located at a position closer to an outer peripheral side of the rectangular region than a light emitting portion of the light source. A planar light source device according to still another aspect of the present invention comprises: a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, the planar light source device further comprising a diffusion lens that is disposed correspondingly to each of the plurality of light sources and diffuses light emitted from the light source, wherein the rectangular region has, at four corners thereof, corner regions where at least one of the light sources is disposed, and the diffusion lens corresponding to the light source located in each of the corner regions is disposed such that a central axis thereof inclines from a direction perpendicular to the mounting surface toward an outer peripheral side of the rectangular region. A liquid crystal display device according to still another aspect of the present invention comprises: the above planar light source device, and a liquid crystal panel that modulates light supplied from the planar light source device to perform display. Advantageous Effects of Invention According to the present invention, by suitably setting the disposition angles of the light sources located in the four corner regions of the mounting surface, the mounting positions and mounting angles of the diffusion lenses corresponding to the light sources, even in the structure in which to achieve low cost by reduction in the number of the light sources mounted, the disposition region for the light sources is made smaller than the size of the bottom plate and the disposition density of the light sources in the disposition region is made lower in the peripheral portion than in the central portion, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of illumination from the light source in each of the corner regions. BRIEF DESCRIPTION OF DRAWINGS FIG. 1A is a cross-sectional view showing a schematic structure of a liquid crystal display device according to an embodiment 1 of the present invention. FIG. 1B is a plan view of a backlight of the above liquid crystal display device. FIG. 2 is a cross-sectional view of a diffusion lens of the above backlight. FIG. 3A is a plan view showing schematically a division example when a rectangular region on which a plurality of LEDs are disposed is divided into a plurality of regions on a bottom plate of the above backlight. FIG. 3B is a descriptive view showing an address of each division region in the above division example. FIG. 4 is a descriptive view showing schematically LEDs disposed in four corner regions of the above rectangular region and a brightness distribution of light emitted from the LEDs via diffusion lenses. FIG. 5A is a plan view showing schematically another division example of the above rectangular region. FIG. 5B is a descriptive view showing an address of each division region in the above division example. FIG. 6 is a plan view showing another structure of the above backlight. FIG. 7 is a plan view showing still another structure of the above backlight. FIG. 8 is a plan view showing still another structure of the above backlight. FIG. 9 is a plan view of a backlight according to an embodiment 2 of the present invention. FIG. 10 is a descriptive view showing schematically LEDs disposed in four corner regions of a rectangular region on which a plurality of LEDs are disposed on a bottom plate of the above backlight and a brightness distribution of light emitted from the LEDs via diffusion lenses. FIG. 11 is a plan view showing schematically another division example of the above rectangular region. FIG. 12 is a plan view showing another structure of the above backlight. FIG. 13 is a plan view showing still another structure of the above backlight. FIG. 14 is a plan view showing still another structure of the above backlight. FIG. 15 is a plan view of a backlight according to an embodiment 3 of the present invention. FIG. 16 is a descriptive view showing schematically LEDs disposed in four corner regions of a rectangular region on which a plurality of LEDs are disposed on a bottom plate of the above backlight and a brightness distribution of light emitted from the LEDs via diffusion lenses. FIG. 17 is a plan view showing schematically another division example of the above rectangular region. FIG. 18 is a plan view showing another structure of the above backlight. FIG. 19 is a plan view showing still another structure of the above backlight. FIG. 20 is a plan view showing still another structure of the above backlight. FIG. 21 is a cross-sectional view showing another disposition example of an LED and a diffusion lens in a corner region of the above rectangular region. FIG. 22 is a cross-sectional view showing still another disposition example of an LED and a diffusion lens in a corner region of the above rectangular region. FIG. 23 is a cross-sectional view showing still another disposition example of an LED and a diffusion lens in a corner region of the above rectangular region. FIG. 24 is a cross-sectional view showing still another disposition example of an LED and a diffusion lens in a corner region of the above rectangular region. FIG. 25 is a plan view showing a structure of a conventional backlight. FIG. 26 is a plan view showing schematically a display screen of a liquid crystal panel illuminated by the backlight. DESCRIPTION OF EMBODIMENTS Embodiment 1 An embodiment 1 of the present invention is described based on drawings as follows. In the meantime, there is a case where structures common to each embodiment are indicated by the same member numbers and description of them is skipped. FIG. 1A is a cross-sectional view showing a schematic structure of a liquid crystal display device 1 according to the present embodiment, and FIG. 1B is a plan view of a backlight 3 of the liquid crystal display device 1 . In the meantime, in FIG. 1B , for the sake of convenience, illustration of a diffusion plate 15 and an optical sheet 16 described later is skipped. As shown in these drawings, the liquid crystal display device 1 has a liquid crystal panel 2 and a backlight 3 . The liquid crystal panel 2 is a liquid crystal display element that modulates light supplied from the backlight 3 to display an image, and composed by sandwiching a liquid layer by means of a pair of boards. One board is provided with a source wiring and a gate wiring disposed to cross each other at right angles, a switching element (e.g., TFT: Thin Film Transistor) that performs ON/OFF of driving of a pixel enclosed by the source wiring and the gate wiring adjacent to each other, a pixel electrode connected to the switching element and the like. The other board is provided with a color filter formed of color filters of R (red), G (green), and B (blue) disposed correspondingly to each pixel, a common electrode common to each pixel and the like. Besides, a side of each board facing the liquid crystal layer is provided with an orientation film that orients liquid crystal molecules, while an outer side (opposite to the liquid crystal layer) of each board is provided with a light polarization plate that transmits predetermined polarized light only. The backlight 3 is a planar light source device (illumination device) of direct type that is disposed right under a rear surface of the liquid crystal panel 2 and illuminates the liquid crystal panel 2 in a planar manner. The backlight 3 includes a backlight chassis 11 , LEDs 12 as a plurality of light sources, an LED board 13 , a diffusion lens 14 , a diffusion plate 15 , an optical sheet 16 , a reflection sheet 17 , and a not-shown circuit board. The above circuit board is a circuit board that controls light emission from the LED 12 , but may include a circuit board for driving the liquid crystal panel 2 and other boards (power source board, control board). The backlight chassis 11 is a chassis member that is formed by bending a sheet metal into a predetermined shape, has a bottom plate 11 a and a side plate 11 b . The bottom plate 11 a is formed into a rectangular shape when viewing from top, and on one surface of which (surface facing the liquid crystal panel 2 ) the plurality of LEDs 12 are mounted via the LED board 13 . Hereinafter, this surface is called a mounting surface 11 a 1 on which the plurality of LEDs 21 are mounted. The side plate 11 b is connected to an outer peripheral portion (four side edge portions of the bottom plate 11 a ) of the bottom plate 11 a to rise substantially upright from the bottom plate 11 a. The LEDs 12 are each a light emitting diode (point light source) that has a light emitting portion 12 a (see FIG. 2 ) and mouthed in a line on the LED board 13 as a mounting board. A plurality of the LED boards 13 are disposed in parallel on the bottom plate 11 a . In this way, the plurality of LEDs 12 are disposed two-dimensionally on the bottom plate 11 a . In the present embodiment, because the reflection sheet 17 described later is provided with an edge portion 17 b , on the bottom plate 11 a , a disposition region for the LEDs 12 is a rectangular region RA smaller than a size of the bottom plate 11 a. Here, two directions parallel to the mounting surface 11 a 1 of the bottom plate 11 a and perpendicular to each other are defined as an H direction (first direction) and a V direction (second direction), respectively. In the meantime, the H direction corresponds to, for example, a long-edge direction of the rectangular region RA, while the V direction corresponds to a short-edge direction of the rectangular region. The size of the rectangular region RA is H1 (cm)×V1 (cm), while the size of the bottom plate 11 a is H2 (cm)×V2 (cm), where H1<H2, V1<V2. As described above, the rectangular region RA is one size smaller than the size of the bottom plate 11 a. Besides, on the bottom plate 11 a , the disposition interval of the LED boards 13 is narrow in a central portion Rc in the arrangement direction of the LED boards 13 and wide in an outer peripheral portion Rp with respect to the central portion Rc in the arrangement direction. As a result of this, the disposition density of the LEDs 12 is high in the central portion Rc of the rectangular region RA and low in the peripheral portion Rp. As described above, by partially changing the disposition density of the LEDs 12 , it is possible to secure an illumination brightness in a necessary region (central region Rc) and to achieve low cost by reducing the number of LEDs 12 mounted as a whole. Besides, by adjusting the disposition interval of the LED boards 13 to partially change the disposition density of the LEDs 12 , it is also possible to easily deal with a size change of the backlight 3 . The diffusion lens 14 is disposed on the LED board 13 correspondingly to each of the plurality of LEDs 12 and diffuses the light emitted from each LED 12 . In the meantime, a detailed structure of the diffusion lens 14 is described later. By disposing the diffusion lens 14 , the light from the LED 12 is diffused by the diffusion lens 14 ; accordingly, even in a case where the interval between neighboring LEDs 12 is large, dot-like unevenness becomes unlikely to occur in a brightness distribution by each LED 12 . As a result of this, it is possible to achieve low cost by further reducing the number of LEDs 12 mounted. In the meantime, in a case where it is possible to amply reduce the number of LEDs 12 mounted by adjusting the above disposition interval of the LED boards 13 , it is also possible to employ a structure in which the diffusion lens 14 is not disposed. The diffusion plate 15 further diffuses and averages the light emitted from each LED 12 via the diffusion lens 14 , is formed into a flat plate shape and disposed at a position closer to the liquid crystal panel 2 than the diffusion lens 14 . The optical sheet 16 outputs the light, which passes through the diffusion plate 15 , as planar light and is composed to include a lens sheet, a prism sheet, a retroreflection sheet and the like. Respective end portions of the diffusion plate 15 and optical sheet 16 are supported by the side plate 11 b of the backlight chassis 11 via end portions of the reflection sheet 17 . The reflection sheet 17 has an opening portion 17 a from which each LED 12 is exposed, is disposed on the bottom plate 11 a to cover the LED board 13 , and reflects the light, which is emitted from the LED 12 and directly enters the reflection sheet, and the light, which is emitted from the LED 12 and reflected by the diffusion plate 15 and the like to enter the reflection sheet, again to the liquid crystal panel 2 . In this way, it is possible to improve use efficiency of the light emitted from the LED 12 . The reflection sheet 17 has the edge portion 17 b that rises obliquely from the bottom plate 11 a outside the rectangular region RA. In other words, the edge portion 17 b is located to surround the rectangular region RA. An end portion (outer peripheral portion) of the edge portion 17 b is supported from under by the side plate 11 b of the backlight chassis 11 . By disposing the reflection sheet 17 , even if the LEDs 12 are not disposed on the outer peripheral portions of the bottom plate 11 a , it is possible to illuminate screen peripheral portions of the liquid crystal panel 2 by means of the light that is emitted from the LEDs 12 and reflected by the edge portion 17 b of the reflection sheet 17 . Accordingly, it is possible to achieve low cost by further reducing the number of LEDs 12 mounted all the more because the LEDs 12 are not disposed on the peripheral portions of the bottom plate 11 a. Next, details of a structure of the above diffusion lens 14 are described. FIG. 2 a cross-sectional view of the diffusion lens 14 . The diffusion lens 14 has a lens portion 14 a and a plurality of leg portions 14 b (e.g., three) that support the lens portion 14 a on the LED board 13 , and is formed into a rotator shape (circular shape when viewing from top) as a whole. The leg portions 14 b are disposed at an equal interval (e.g., angle interval of 120°) in a direction along an outer circumference of the lens portion 14 a , and mounted at predetermined of the LED board 13 positions by means of an adhesive (not shown), for example. By adjusting a length of each leg portion 14 b , it is possible to adjust a mounting angle of the diffusion lens 14 to the LED board 13 ; however, in the present embodiment, the lengths of the leg portions 14 b are all the same. As a result of this, a central axis (optical axis) C of the diffusion lens 14 is perpendicular to the mounting surface 11 a of the bottom plate 11 a. The lens portion 14 a has a light output surface (upper surface) 14 c and a lower surface 14 d . The light output surface 14 c is formed into a concave shape recessed toward the LED 12 at a central region close to the central axis C and formed into a convex shape raised oppositely to the LED 12 in an outer circumferential region with respect to the central region in a lens radial direction. Besides, in the lower surface 14 d , a portion opposite to the LED 12 has a concave portion 14 e that is recessed oppositely to the LED 12 . According to such structure of the diffusion lens 14 , the light emitted from the LED 12 is changed (diffused) in travelling direction to the outside by the concave portion 14 e and the light output surface 14 c , so that a light expansion angle becomes large. In the meantime, the shapes of the light output surface 14 c and lower surface 14 d of the diffusion plate 14 are not limited to the above shapes, and whatever shapes may be employed if the shapes diffuse (enlarge the light expansion angle) the light emitted from the LED 12 . Accordingly, for example, it is also possible to compose the diffusion lens 14 without disposing the concave portion recessed toward the LED 12 at the central region of the light output surface 14 c , and also possible to compose the diffusion lens 14 without forming the concave portion 14 e in the lower surface 14 d. Next, a structure, which alleviates a brightness decline at the screen four corners of the liquid crystal panel 2 as an illumination target, is described. FIG. 3A is a plan view showing schematically a division example when the rectangular region RA on which the plurality of LEDs 12 are disposed is divided into a plurality of regions on the bottom plate 11 a , and FIG. 3B is a descriptive view showing addresses of the plurality of divided regions (hereinafter, also called a division region). In FIG. 3A , the rectangular region RA is divided into, for example, 7 regions in the H direction (long-edge direction) and into, for example, 4 regions in the V direction (short-edge direction); accordingly, FIG. 3B shows a total of 28 regions R ij , where i is an integer of 1 to 4 and corresponds to a number of a row parallel to the H direction, while j is an integer of 1 to 7 and corresponds to a number of a column parallel to the V direction. Here, for the sake of convenience for the following description, in the rectangular region RA, regions R 11 ·R 17 ·R 41 ·R 47 located in the four corners are called corner regions P 1 . Besides, in the rectangular region RA, regions located in outermost peripheral portions including the four corner regions P 1 , namely, regions R 11 to R 17 , regions R 21 ·R 27 , regions R 31 ·R 37 , and regions R 41 to R 47 are called outer peripheral regions P 2 . Further, in the rectangular region RA, the remaining regions except for the corner regions P 1 and outer peripheral regions P 2 , namely, regions R 22 to R 26 and regions R 32 to R 36 located (surrounded by the outer peripheral regions P 2 ) inside the outer peripheral regions P 2 are called central regions P 3 . In FIG. 3B , to facilitate the identification of the corner regions P 1 , outer peripheral regions P 2 and central regions P 3 , these three kinds of regions are indicated by symbols of ∘, Δ, and □, respectively. In the present embodiment, one LED 12 is disposed in each of the four corner regions P 1 . Besides, the above diffusion lens 14 is disposed correspondingly to each LED 12 ; accordingly, one diffusion lens 14 is disposed in each corner region P 1 . FIG. 4 shows schematically the LEDs 12 disposed in the four corner regions P 1 and a brightness distribution of the light emitted from the LEDs 12 via the diffusion lenses 14 . In the present embodiment, the LED 12 located in each corner region P 1 is disposed such that a central axis D thereof inclines from a direction perpendicular to the bottom plate 11 a (mounting surface 11 a 1 ) toward the outer peripheral side of the rectangular region RA, especially toward each apex of the four corners of the rectangular region RA. In the meantime, in FIG. 3A , an arrow attached to the LED 12 indicates the direction in which the central axis D of the LED 12 inclines, and other drawings appearing in the present embodiment are illustrated in the same way as this. Besides, as to the LED 12 with no arrow attached, the central axis D is in the direction perpendicular to the bottom plate 11 a. In the meantime, the central axis D of the LED 12 has the same meaning as a central axis (optical axis) of the light flux emitted from the LED 12 . In other words, an axis, which passes through the light emitting portion 12 a of the LED 12 and a position where intensity (radiation intensity) of the light emitted from the LED 12 becomes the highest, is defined as the central axis D of the LED 12 . Here, in the present embodiment, to incline the central axis D of the LED 12 as described above, the LED 12 is mounted on the LED board 13 via a support member 18 . The support member 18 is formed into a triangle pole shape that has a right triangle in cross section and disposed sideways on the LED board 13 . Accordingly, by disposing the LED 12 onto a surface of the support member 18 inclined by an acute angle to the LED board 13 and disposing the support member 18 onto the LED board 13 such that a normal of the surface of the support member 18 faces each apex of the four corners of the rectangular region RA, it is possible to incline the central axis D of the LED 12 as described above. As described above, in the four corner regions P 1 , by disposing the LED 12 such that the central axis D of the LED 12 inclines toward the outer peripheral side of the rectangular region RA, as shown in FIG. 4 , in the brightness distribution of the light emitted from each LED 12 in each corner region P 1 , it is possible to raise the illumination brightness on the side (outer peripheral side of the rectangular region RA) toward which the central axis D inclines with respect to an axis (e.g., central axis C of the diffusion lens 14 ) that passes through the LED 12 (light emitting portion 12 a ) and is perpendicular to the mounting surface 11 a 1 . In this way, even in the structure in which low cost is achieved by reduction in the number of LEDs 12 mounted, namely, even in the structure in which the disposition region for the LEDs 12 is made smaller than the size of the bottom plate 11 a and the disposition density of the LEDs 12 in the disposition region is made lower in the peripheral portion Rp than in the central portion Rc, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 . Especially, in a case where the number of LEDs 12 mounted is further reduced, or in a case where thickness reduction of the backlight 3 is pursued, the brightness at the four corners of the illumination region easily declines; accordingly, as described above, the structure in which the LED 12 inclines to alleviate the brightness decline at the four corners becomes very effective. Besides, in the liquid crystal display device 1 that illuminates the liquid crystal panel 2 by means of the backlight 3 having the above structure, it is possible to alleviate the brightness declining at the four corners of the screen of the liquid crystal panel 2 ; accordingly, it is possible to improve display quality. Besides, the LED 12 located in each corner region P 1 is disposed such that the central axis D thereof inclines toward each apex of the four corners of the rectangular region RA; accordingly, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 . Accordingly, it is possible to surely alleviate the brightness declining at the four corners of the illumination region. In the meantime, the above effects are obtainable even in a case where the diffusion lens 14 is not disposed over the light emitting side of the LED 12 . However, in the case where the diffusion lens 14 is disposed, the light from the LED 12 is diffused by the diffusion lens 14 , so that the brightness decline at the four corners of the illumination region becomes less conspicuous; accordingly, in this point, it is desirable to employ the structure in which the diffusion lens 14 is disposed. Besides, in the backlight 3 of direct type that illuminates the liquid crystal panel 2 from right under, brightness unevenness (e.g., brightness decline at the four corners of the screen) easily occurs in the liquid crystal panel 2 compared to an edge-light type that shines light onto an end surface of a light guide plate to illuminate the liquid crystal panel 2 in a planar manner. Accordingly, the above structure, which alleviates the brightness decline at the four corners of the screen by disposing and inclining the LED 12 in each corner region P 1 , becomes very effective. Besides, in the case where the LED 12 is used as the light source of the backlight 3 , the brightness decline due to the reduction in the number of light sources mounted easily occurs at the four corners of the screen compared to a case where a tube-like light source (e.g., cold-cathode tube) is used. Accordingly, in the case where the LED 12 is used as the light source, the above structure, which alleviates the brightness decline at the four corners of the screen by disposing and inclining the LED 12 in each corner region P 1 , becomes very effective. Besides, in the case where the diffusion sheet 17 is disposed in the backlight 3 , as described above, it is possible to illuminate the screen peripheral portion of the liquid crystal panel 2 by means of the light reflected by the edge portion 17 b of the reflection sheet 17 . However, in this case, the LED 12 is not disposed on the peripheral portion of the bottom plate 11 a ; accordingly, it is possible to reduce the number of LEDs 12 mounted, but the light has difficulty in reaching the four corners of the screen of the liquid crystal panel 2 . Accordingly, in the case where the liquid crystal panel 2 is illuminated by means of the edge portion 17 b of the reflection sheet 17 (case where the reduction in the number of LEDs 12 mounted is achieved), to alleviate the brightness decline at the four corners of the screen, the structure which inclines the LED 12 in each corner region P 1 becomes very effective. In the meantime, hereinbefore, the structure is described, in which one LED 12 is disposed in each division region of the rectangular region RA and one LED 12 in the corner region P 1 is inclined; however, a structure may be employed, in which a plurality of LEDs 12 are disposed in each division region and the plurality of LEDs 12 in the corner region P 1 are inclined. In other words, in the case where the total number of LEDs 12 is constant, a structure may be employed, which relatively reduces the number of division regions, increases the number of LEDs 12 disposed in one division region, and inclines the plurality of LEDs 12 in the corner region P 1 . Hereinafter, this point is described more specifically. FIG. 5A is a plan view showing schematically another division example of the rectangular region RA, and FIG. 5B is a descriptive view showing an address of each division region. In FIG. 5A , the rectangular region RA is divided into, for example, 3 regions in the H direction and into, for example, 3 regions in the V direction; accordingly, FIG. 5B shows a total of 9 regions R ij , where i is an integer of 1 to 3 and corresponds to a number of a row parallel to the H direction, while j is an integer of 1 to 3 and corresponds to a number of a column parallel to the V direction. Here, in the rectangular region RA, regions R 11 ·R 13 ·R 31 ·R 33 located in the four corners are called the corner regions P 1 . Besides, in the rectangular region RA, regions located in the outermost peripheral portions including the four corner regions P 1 , namely, regions R 11 to R 13 , regions R 21 ·R 23 , regions R 31 to R 33 are called the outer peripheral regions P 2 . Further, in the rectangular region RA, regions except for the corner regions P 1 and outer peripheral regions P 2 , namely, a regions R 22 located (surrounded by the outer peripheral regions P 2 ) inside the outer peripheral regions P 2 is called the central regions P 3 . In FIG. 5B , to facilitate the identification of the corner regions P 1 , outer peripheral regions P 2 and central regions P 3 , these three kinds of regions are indicated by symbols of ∘, Δ, and □, respectively. In the case where the total number of LEDs 12 is the same as in FIG. 3A and FIG. 3B and the number of division regions in the rectangular region RA is reduced as in FIG. 5A and FIG. 5B , the number of LEDs 12 disposed in one division region increases from the case of FIG. 3A and FIG. 3B . In this example, two LEDs 12 are disposed in each corner region P 1 . In the meantime, the above diffusion lens 14 is disposed correspondingly to each LED 12 ; accordingly, also two diffusion lenses 14 are disposed in each corner region P 1 . As described above, by disposing the plurality of LEDs 12 in the corner regions P 1 such that the central axis D inclines toward the outer peripheral side of the rectangular region RA, the amount of the light supplied to the four corners of the illumination region by the plurality of LEDs 12 in the corner regions P 1 increases compared to the structure in which one LED 12 is inclined. Accordingly, it is possible to more alleviate the brightness decline at the four corners of the illumination region. From the above description, it can be said preferable if the rectangular region RA in which the LEDs 12 are disposed has, at the four corners, the corner regions P 1 in each of which at least one LED 12 is disposed and the LED 12 located in each corner region P 1 is disposed such that the central axis D thereof inclines toward the outer peripheral side of the rectangular region RA. Besides, to secure a high illumination brightness at the central portion of the illumination region while alleviating the brightness decline at the four corners of the illumination region by means of the LEDs 12 in the four corner regions P 1 , it is necessary to illuminate the central portion of the illumination region by means of LEDs 12 in the central region of the rectangular region RA while preventing the central axes D of the LEDs 12 in the central region from inclining toward the outer peripheral side of the rectangular region RA. At this time, for example, if the rectangular region RA is divided into a total of four regions with divided into 2 regions in the H direction and divided into 2 regions in the V direction, all of these four regions become the corner regions P 1 that include each apex of the four corners, and the central axes D of all the LEDs 12 incline toward the outer peripheral side. In other words, in this case, it is impossible to allow a region, in which the central axis D of the LED 12 does not incline, to exist in the rectangular region RA. Accordingly, in the present embodiment, by dividing the rectangular region RA into at least 9 regions with divided into 3 or more regions in the H direction and divided into 3 or more regions in the V direction, it is possible to surely alleviate the brightness decline at the four corners of the illumination region by means of the LED 12 in each corner region P 1 while surely achieving improvement in the illumination brightness at the central portion of the illumination region by means of the LED 12 located in a region (e.g., central region P 3 ) except for each corner region P 1 . At this time, each corner region P 1 becomes a region where both-end regions when the rectangular region RA is divided into three or more regions in the H direction and both-end regions when the rectangular region RA is divided into three or more regions in the V direction overlie each other. Besides, hereinbefore, the example is described, in which each central axis D of the LED 12 in each corner region inclines toward each corresponding apex of the four corners from the direction perpendicular to the bottom plate 11 a (mounting surface 11 a ); however, if the central axis D inclines toward the outer peripheral side of the rectangular region RA, the inclination direction is not limited to the direction toward each apex of the four corners. FIG. 6 is a plan view showing another structure of the backlight 3 , and FIG. 7 is a plan view showing still another structure of the backlight 3 . As shown in FIG. 6 and FIG. 7 , the LED 12 in each corner region P 1 may be disposed such that the central axis D thereof inclines from the direction perpendicular to the bottom plate 11 a (mounting surface 11 a 1 ) toward a long edge or a short edge of the rectangular region RA. Besides, FIG. 8 is a plan view showing still another structure of the backlight 3 . The LEDs 12 located in the outer peripheral region P 2 (see FIG. 3B , FIG. 5B ) may be disposed such that each central axis D inclines from the direction perpendicular to the bottom plate 11 a (mounting surface 11 a 1 ) toward the outer peripheral side (long edge, short edge) of the rectangular region RA. In this case, in the brightness distribution of the light emitted from the LED 12 in the outer peripheral region P 2 , it is possible to raise the brightness on the side (outer peripheral side of the rectangular region RA) toward which the central axis D inclines with respect to the axis that passes through the LED 12 and is perpendicular to the mounting surface 11 a 1 . In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and for example, it is possible to alleviate frame-shaped brightness unevenness occurring on the display screen of the liquid crystal panel 2 . Accordingly, it is possible to further reduce the number of light sources in the outer peripheral region. In addition, by illuminating the central portion of the illumination region by means of the LEDs 12 located in the region (central region P 3 ) inside the outer peripheral region P 2 , it is possible to obtain the above effects while securing the brightness at the central portion. Embodiment 2 An embodiment 2 of the present invention is described based on drawings as follows. FIG. 9 is a plan view of the backlight 3 according to the present embodiment. In the meantime, in FIG. 9 , for the sake of convenience, the illustration of the diffusion plate 15 and optical sheet 16 is skipped. In the present embodiment, instead of inclining the LED 12 located in each corner region P 1 of the rectangular region RA in the structure according to the embodiment 1, the position of the diffusion lens 14 corresponding to the above LED 12 is deviated with respect to the LED 12 . In more detail, the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 is disposed such that the central axis C thereof inclines toward the outer peripheral side of the rectangular region RA, especially toward each apex of the four corners of the rectangular region RA with respect to the light emitting portion 12 a of the LED 12 . In the meantime, in FIG. 9 , an arrow attached to the diffusion lens 14 indicates the direction in which the diffusion lens 14 deviates with respect to the LED 12 , and other drawings appearing in the present embodiment are illustrated in the same way as this. Besides, as to the diffusion lens 14 with no arrow attached, the central axis C does not deviate (passes through the light emitting portion 12 a ) from the light emitting portion 12 a of the LED 12 . FIG. 10 shows schematically the LEDs 12 disposed in the four corner regions P 1 and a brightness distribution of the light emitted from the LEDs 12 via the diffusion lenses 14 . In the present embodiment, the central axis C of the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portion 12 a of the LED 12 , so that in the above brightness distribution, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 deviates) of the rectangular region RA compared to the case where the diffusion lens 14 is not deviated. In this way, even in the structure in which to achieve low cost by reduction in the number of LEDs 12 mounted, the disposition region for the LEDs 12 is made smaller than the size of the bottom plate 11 a and the disposition density of the LEDs 12 in the disposition region is made lower in the peripheral portion Rp than in the central portion Rc, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 . Especially, in the corner region P 1 , the diffusion lens 14 is disposed such that the central axis C of the diffusion lens 14 is located at a position closer to each apex of the four corners of the rectangular region RA than the light emitting portion 12 a of the LED 12 ; accordingly, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 and to surely alleviate the brightness declining at the four corners of the illumination region. Here, FIG. 11 is a plan view showing schematically another division example of the rectangular region RA of the backlight 3 according to the present embodiment. In the meantime, in FIG. 11 , for the sake of convenience, the illustration of the diffusion plate 15 and optical sheet 16 is skipped. As shown in the drawing, to dispose a plurality of the LEDs 12 in one division region, the rectangular region RA on the bottom plate 11 a may be divided into 3×3 regions, namely, a total of 9 regions, and the diffusion lenses 14 corresponding to the plurality of LEDs 12 (two in FIG. 11 ) in each corner region P 1 may be disposed such that the central axes C are located at positions closer to the outer peripheral side of the rectangular region RA than the light emitting portions 12 a of the LEDs 12 . In this case, the amount of the light that is emitted from the LEDs 12 in the corner regions P 1 and supplied to the four corners of the illumination region via the diffusion lenses 14 increases compared to the structure in which only one diffusion lens 14 in the corner region P 1 is deviated toward the outer peripheral side. Accordingly, it is possible to more alleviate the brightness decline at the four corners of the illumination region. From the above description, it can be said preferable if the rectangular region RA in which the LEDs 12 are disposed has, at the four corners, the corner regions P 1 in each of which at least one LED 12 is disposed and the diffusion lens 14 corresponding to the LED 12 located in each corner region P 1 is disposed such that the central axis C thereof is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portion 12 a of the LED 12 . Besides, if the diffusion lens 14 is disposed in each corner region P 1 such that the central axis C of the diffusion lens 14 is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portions 12 a of the LEDs 12 , the direction, in which the diffusion lens 14 deviates with respect to the light emitting portion 12 a , is not limited to the direction toward each apex of the four corners. FIG. 12 is a plan view showing another structure of the backlight 3 according to the present embodiment, and FIG. 13 is a plan view showing still another structure of the backlight 3 . As shown in FIG. 12 and FIG. 13 , the diffusion lens 14 in each corner region P 1 may be disposed such that the central axis C thereof is located at a position closer to the long edge or the short edge of the rectangular region RA than the light emitting portion 12 a. Besides, FIG. 14 is a plan view showing still another structure of the backlight 3 . The diffusion lens 14 corresponding to the LED 12 located in the outer peripheral region P 2 (see FIG. 3B , FIG. 5B ) may be disposed such that the central axis C is located at a position closer to the outer peripheral side (long edge, short edge) of the rectangular region RA than the light emitting portions 12 a. In this case, in a brightness distribution of the light that is emitted from the LED 12 in the outer peripheral region P 2 and obtained via the diffusion lens 14 , it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 deviates) of the rectangular region RA with respect to the axis (e.g., central axis D) that passes through the light emitting portion 12 a of the LED 12 and is perpendicular to the mounting surface 11 a 1 compared to the case where the diffusion lens 14 is not deviated. In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and it is possible to alleviate the frame-shaped brightness unevenness occurring on the display screen of the liquid crystal panel 2 , for example. Accordingly, it is possible to further reduce the number of light sources in the outer peripheral region. In addition, by illuminating the central portion of the illumination region by means of the LEDs 12 located in the region (central region P 3 ) inside the outer peripheral region P 2 , it is possible to obtain the above effects while securing the brightness at the central portion. Embodiment 3 An embodiment 3 of the present invention is described based on drawings as follows. FIG. 15 is a plan view of the backlight 3 according to the present embodiment. In the meantime, in FIG. 15 , for the sake of convenience, the illustration of the diffusion plate 15 and optical sheet 16 is skipped. In the present embodiment, instead of inclining the LED 12 located in each corner region P 1 of the rectangular region RA in the structure according to the embodiment 1, the diffusion lens 14 corresponding to the above LED 12 is inclined and disposed. In more detail, the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA, especially toward each apex of the four corners of the rectangular region RA. Besides, in the present embodiment, the above diffusion lens 14 is disposed such that the central axis C thereof passes through the light emitting portion 12 a of the LED 12 . In the meantime, in FIG. 15 , an arrow attached near the diffusion lens 14 indicates a direction in which the central axis C of the diffusion lens 14 inclines from the direction perpendicular to the mounting surface 11 a 1 , and other drawings appearing in the present embodiment are illustrated in the same way as this. Besides, as to the diffusion lens 14 with no arrow attached, the central axis C does not incline (direction perpendicular to the mounting surface 11 a 1 ). Here, in the present embodiment, to incline the central axis C of the diffusion lens 14 as described above, the length of the leg portion 14 b of the diffusion lens 14 is adjusted. For example, by forming the length of the leg portion 14 b of the plurality of leg portions 14 b furthest from the outer peripheral side of the rectangular region RA to be longer than the leg portion 14 b closest to the outer peripheral side of the rectangular region RA, it is possible to incline the central axis C from the direction perpendicular to the bottom plate 11 a toward the above outer peripheral side. In the meantime, also as to the leg portions 14 b other than the above leg portion, the length may be suitably adjusted in accordance with the inclination direction and inclination angle of the central axis C. FIG. 16 shows schematically the LEDs 12 disposed in the four corner regions P 1 and a brightness distribution of the light emitted from the LEDs 12 via the diffusion lenses 14 . In the present embodiment, the central axis C of the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 inclines to lean from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA, so that in the above brightness distribution, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 inclines) of the rectangular region RA with respect to the axis (e.g., central axis D of the LED 12 ) that passes through the light emitting portion 12 a and is perpendicular to the mounting surface 11 a 1 compared to the case where the diffusion lens 14 does not incline. In this way, even in the structure in which to achieve low cost by reduction in the number of LEDs 12 mounted, the disposition region for the LEDs 12 is made smaller than the size of the bottom plate 11 a and the disposition density of the LEDs 12 in the disposition region is made lower in the peripheral portion Rp than in the central portion Rc, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 . Especially, in the corner region P 1 , the diffusion lens 14 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward each apex of the four corners of the rectangular region RA; accordingly, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 and to surely alleviate the brightness declining at the four corners of the illumination region. Here, FIG. 17 is a plan view showing schematically another division example of the rectangular region RA of the backlight 3 according to the present embodiment. In the meantime, in FIG. 17 , for the sake of convenience, the illustration of the diffusion plate 15 and optical sheet 16 is skipped. As shown in the drawing, to dispose a plurality of the LEDs 12 in one division region, the rectangular region RA on the bottom plate 11 a may be divided into a plurality of regions (e.g., a total of 9 regions of 3×3) and the diffusion lenses 14 corresponding to the plurality of LEDs 12 (two in FIG. 17 ) in each corner region P 1 may be disposed such that the central axes C incline from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA. In this case, the amount of the light that is emitted from the LEDs 12 in the corner region P 1 and supplied to the four corners of the illumination region via the diffusion lenses 14 increases compared to the structure in which only one diffusion lens 14 in the corner region P 1 is inclined toward the outer peripheral side. Accordingly, it is possible to more alleviate the brightness decline at the four corners of the illumination region. From the above description, it can be said preferable if the rectangular region RA in which the LEDs 12 are disposed has, at the four corners, the corner regions P 1 in each of which at least one LED 12 is disposed and the diffusion lens 14 corresponding to the LED 12 located in each corner region P 1 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA. Besides, in each corner region P 1 , if the diffusion lens 14 is disposed such that the central axis C of the diffusion lens 14 inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA, the direction in which the diffusion lens 14 inclines is not limited to a direction toward each apex of the four corners of the rectangular region RA. FIG. 18 is a plan view showing another structure of the backlight 3 , and FIG. 19 is a plan view showing still another structure of the backlight 3 . As shown in FIG. 18 and FIG. 19 , the diffusion lens 14 in each corner region P 1 may be disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the long edge or the short edge of the rectangular region RA. Besides, FIG. 20 is a plan view showing still another structure of the backlight 3 . The diffusion lens 14 corresponding to the LED 12 located in the outer peripheral region P 2 (see FIG. 3B , FIG. 5B ) may be disposed such that the central axis C inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side (long edge, short edge) of the rectangular region RA. In this case, in a brightness distribution of the light that is emitted from the LED 12 in the outer peripheral region P 2 and obtained via the diffusion lens 14 , it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 inclines) of the rectangular region RA with respect to the axis (e.g., central axis D of the LED 12 ) that passes through the light emitting portion 12 a and is perpendicular to the mounting surface 11 a 1 compared to the case where the diffusion lens 14 does not incline. In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and it is possible to alleviate the frame-shaped brightness unevenness occurring on the display screen of the liquid crystal panel 2 , for example. Accordingly, it is possible to further reduce the number of light sources in the outer peripheral region. In addition, by illuminating the central portion of the illumination region by means of the LEDs 12 located in the region (central region P 3 ) inside the outer peripheral region P 2 , it is possible to obtain the above effects while securing the brightness at the central portion. [Supplement] It is of course possible to compose the backlight 3 and the liquid crystal display device 1 by suitably combining the above embodiments. Hereinafter, combinations of the embodiments are described. FIG. 21 is a cross-sectional view showing another disposition example of the LED 12 and diffusion lens 14 in the corner region P 1 of the rectangular region RA. As shown in the drawing, the backlight 3 may have a structure obtained by combining the embodiments 1 and 2. In other words, the backlight 3 may be structured in such a way that (1) the LED 12 in each corner region P 1 is disposed such that the central axis D thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA and (2) the diffusion lens 14 in each corner region P 1 is disposed such that the central axis C thereof is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portion 12 a of the LED 12 . In this structure, in the brightness distribution of the light that is emitted from the LED 12 in each corner region P 1 and obtained via the diffusion lens 14 , even in a case where the inclination angle (inclination angle to the direction perpendicular to the mounting surface 11 a 1 ) of the central axis D of the LED 12 is small, because of the above disposition of the diffusion lens 14 , it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 deviates) of the rectangular region RA with respect to the axis that passes through the light emitting portion 12 a and is perpendicular to the mounting surface 11 a 1 . In this way, even in the case where the inclination angle of the central axis D of the LED 12 is small, it is possible to surely obtain the effect of alleviating the brightness declining at the four corners of the illumination region. Besides, in a case where the inclination angle of the central axis D of the LED 12 is enlarged, it is possible to further alleviate the brightness declining at the four corners of the illumination region in cooperation with the above disposition of the diffusion lens 14 . Besides, FIG. 22 is a cross-sectional view showing still another disposition example of the LED 12 and diffusion lens 14 in the corner region P 1 of the rectangular region RA. As shown in the drawing, the backlight 3 may have a structure obtained by combining the embodiments 1 and 3. In other words, the backlight 3 may be structured in such a way that (1) the LED 12 in each corner region P 1 is disposed such that the central axis D thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA and (2) the diffusion lens 14 in each corner region P 1 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA. In this structure, in the brightness distribution of the light that is emitted from the LED 12 in each corner region P 1 and obtained via the diffusion lens 14 , even in a case where the inclination angle of the central axis D of the LED 12 is small, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 inclines) of the rectangular region RA with respect to the axis that passes through the light emitting portion 12 a and is perpendicular to the mounting surface 11 a 1 . In this way, even in the case where the inclination angle of the central axis D of the LED 12 is small, it is possible to surely obtain the effect of alleviating the brightness declining at the four corners of the illumination region. Besides, in a case where the inclination angle of the central axis D of the LED 12 is enlarged, it is possible to further alleviate the brightness declining at the four corners of the illumination region in cooperation with the above disposition of the diffusion lens 14 . Besides, FIG. 23 is a cross-sectional view showing still another disposition example of the LED 12 and diffusion lens 14 in the corner region P 1 of the rectangular region RA. As shown in the drawing, the backlight 3 may have a structure obtained by combining the embodiments 2 and 3. In other words, the backlight 3 may be structured in such a way that (1) the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 is disposed such that the central axis C thereof is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portion 12 a of the LED 12 and (2) the diffusion lens 14 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA. In this structure, in the brightness distribution of the light that is emitted from the LED 12 in each corner region P 1 and obtained via the diffusion lens 14 , even in a case where the deviation amount of the diffusion lens 14 from the light emitting portion 12 a is small, it is possible to raise the brightness on the outer peripheral side of the rectangular region RA with respect to the axis (e.g., central axis D of the LED 12 ) that passes through the light emitting portion 12 a and is perpendicular to the mounting surface 11 a 1 . In this way, even in the case where the deviation amount of the diffusion lens 14 from the light emitting portion 12 a is small, it is possible to surely obtain the effect of alleviating the brightness declining at the four corners of the illumination region. Besides, in a case where the deviation amount of the diffusion lens 14 is enlarged, it is possible to further alleviate the brightness declining at the four corners of the illumination region in cooperation with the above inclination of the diffusion lens 14 . Besides, FIG. 24 is a cross-sectional view showing still another disposition example of the LED 12 and diffusion lens 14 in the corner region P 1 of the rectangular region RA. As shown in the drawing, the backlight 3 may have a structure obtained by combining all the embodiments 1 to 3. In other words, the backlight 3 may be structured in such a way that (1) the LED 12 in each corner region P 1 is disposed such that the central axis D thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA, (2) the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 is disposed such that the central axis C thereof is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portion 12 a of the LED 12 , further (3) the diffusion lens 14 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA. In this structure, in the brightness distribution of the light that is emitted from the LED 12 in each corner region P 1 and obtained via the diffusion lens 14 , even in a case where at least one of the inclination angle of the LED 12 , the deviation amount of the diffusion lens 14 and the inclination angle of the diffusion lens 14 is small, it is possible to raise the brightness on the outer peripheral side of the rectangular region RA and to alleviate the brightness declining at the four corners of the illumination region. Besides, it is possible to significantly alleviate the brightness declining at the four corners of the illumination region by means of a synergy effect of the inclination of the LED 12 , the deviation of the diffusion lens 14 and the inclination of the diffusion lens 14 . In the meantime, the planar light source device and liquid crystal display device represented in each embodiment are expressible as follows. A planar light source device according to one embodiment of the present invention comprises a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, wherein the rectangular region has, at four corners thereof corner regions where at least one of the light sources is disposed, and the light source located at each of the corner regions is disposed such that a central axis thereof inclines from a direction perpendicular to the mounting surface toward an outer peripheral side of the rectangular region. According to the above structure, in the brightness distribution of the light emitted from the light source in each corner region, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis inclines with respect to the axis that passes through the light source and is perpendicular to the mounting surface. In this way, even in the structure in which to achieve low cost by reduction in the number of light sources mounted, the disposition region for the light sources is made smaller than the size of the bottom plate and the disposition density of the light sources in the disposition region is made lower in the peripheral portion than in the central portion, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the light source in each corner region. In the above planar light source device, the light source located in each of the corner regions may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward each apex of the four corners of the rectangular region. In this case, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the light source in each corner region and to surely alleviate the brightness declining at the four corners of the illumination region. The above planar light source device may include a diffusion lens that is disposed correspondingly to each of the plurality of light sources and diffuses the light emitted from the light source. In this case, the light from the light source is diffused by the diffusion lens; accordingly, the brightness decline at the four corners becomes more inconspicuous. Besides, even in a case where the interval between neighboring light sources is large, dot-like unevenness becomes unlikely to occur in the brightness distribution by each light source; accordingly, it is possible to achieve low cost by further reducing the number of light sources mounted. In each of the corner regions of the above planar light source device, the diffusion lens may be disposed such that a central axis thereof is located at a position closer to the outer peripheral side of the rectangular region than the light emitting portion of the light source. In this structure, in the brightness distribution of the light that is emitted from the light source and obtained via the diffusion lens, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens deviates) of the rectangular region with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface. In this way, even in the case where the inclination angle of the central axis of the light source is small, it is possible to surely alleviate the brightness declining at the four corners of the illumination region. In each of the corner regions of the above planar light source device, the diffusion lens may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward the outer peripheral side of the rectangular region. In this structure, in the brightness distribution of the light that is emitted from the light source and obtained via the diffusion lens, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis of the diffusion lens inclines with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface. In this way, even in the case where the inclination angle of the central axis of the light source is small, it is possible to surely alleviate the brightness declining at the four corners of the illumination region. In the above planar light source device, when the rectangular region is divided into an outermost peripheral region including each of the corner regions and an inner region with respect to the outermost peripheral region, the light source located in the outermost peripheral region may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward the outer peripheral side of the rectangular region. In this case, in the brightness distribution of the light emitted from the light source in the outermost peripheral region in the rectangular region, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis inclines with respect to the axis that passes through the light source and is perpendicular to the mounting surface. In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and it is possible to alleviate the frame-shaped brightness unevenness occurring. In addition, by illuminating the central portion of the illumination region by means of the light sources located in the region inside the outermost peripheral region, it is possible to obtain the above effects while securing the brightness at the central portion. A planar light source device according to another embodiment of the present invention comprises a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, the planar light source device further comprising a diffusion lens that is disposed correspondingly to each of the plurality of light sources and diffuses light emitted from the light source, wherein the rectangular region has, at four corners thereof, corner regions where at least one of the light sources is disposed, and the diffusion lens corresponding to the light source located in each of the corner regions is disposed such that a central axis thereof is located at a position closer to an outer peripheral side of the rectangular region than a light emitting portion of the light source. According to the above structure, in the brightness distribution of the light that is emitted from the light source in each corner region and obtained via the diffusion lens, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens deviates) of the rectangular region with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface. In this way, even in the structure in which to achieve low cost by reduction in the number of light sources mounted, the disposition region for the light sources is made smaller than the size of the bottom plate and the disposition density of the light sources in the disposition region is made lower in the peripheral portion than in the central portion, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the light source in each corner region. Besides, the light from the light source is diffused by the diffusion lens; accordingly, the brightness decline at the four corners becomes more inconspicuous. Besides, even in the case where the interval between neighboring light sources is large, the dot-like unevenness becomes unlikely to occur in the brightness distribution by each light source; accordingly, it is possible to achieve low cost by further reducing the number of light sources mounted. In the above planar light source device, the diffusion lens may be disposed such that the central axis thereof is located at a position closer to each apex of the four corners of the rectangular region than the light emitting portion of the light source. In this case, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the light source in each corner region and to surely alleviate the brightness declining at the four corners of the illumination region. In the above planar light source device, the diffusion lens may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward the outer peripheral side of the rectangular region. In this structure, in the brightness distribution of the light that is emitted from the light source and obtained via the diffusion lens, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis of the diffusion lens inclines with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface. In this way, even in the case where the deviation amount of the diffusion lens with respect to the light source (light emitting portion) is small, it is possible to alleviate the brightness declining at the four corners of the illumination region. In the above planar light source device, when the rectangular region is divided into the outermost peripheral region including each of the corner regions and the inner region with respect to the outermost peripheral region, the diffusion lens corresponding to the light source located in the outermost peripheral region may be disposed such that the central axis thereof is located at a position closer to the outer peripheral side of the rectangular region than the light emitting portion of the light source. In this case, in the brightness distribution of the light that is emitted from the light source in the outermost peripheral region in the rectangular region and obtained via the diffusion lens, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens deviates) of the rectangular region with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface. In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and it is possible to alleviate the frame-shaped brightness unevenness occurring. In addition, by illuminating the central portion of the illumination region by means of the light sources located in the region inside the outermost peripheral region, it is possible to obtain the above effects while securing the brightness at the central portion. A planar light source device according to still another embodiment of the present invention comprises a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, the planar light source device further comprising a diffusion lens that is disposed correspondingly to each of the plurality of light sources and diffuses light emitted from the light source, wherein the rectangular region has, at four corners thereof, corner regions where at least one of the light sources is disposed, and the diffusion lens corresponding to the light source located in each of the corner regions is disposed such that a central axis thereof inclines from a direction perpendicular to the mounting surface toward an outer peripheral side of the rectangular region. According to the above structure, in the brightness distribution of the light that is emitted from the light source in each corner region and obtained via the diffusion lens, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis of the diffusion lens inclines with respect to the axis that passes through the light source and is perpendicular to the mounting surface. In this way, even in the structure in which to achieve low cost by reduction in the number of light sources mounted, the disposition region for the light sources is made smaller than the size of the mounting surface and the disposition density of the light sources in the disposition region is made lower in the peripheral portion than in the central portion, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the light source in each corner region. Besides, the light from the light source is diffused by the diffusion lens; accordingly, the brightness decline at the four corners of the illumination region becomes more inconspicuous. Besides, even in the case where the interval between the neighboring light sources is large, the dot-like unevenness becomes unlikely to occur in the brightness distribution by each light source; accordingly, it is possible to achieve low cost by further reducing the number of light sources mounted. In the above planar light source device, the diffusion lens may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward each apex of the four corners of the rectangular region. In this case, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the light source in each corner region and to surely alleviate the brightness declining at the four corners of the illumination region. In the above planar light source device, when the rectangular region is divided into the outermost peripheral region including each of the corner regions and the inner region with respect to the outermost peripheral region, the diffusion lens corresponding to the light source located in the outermost peripheral region may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward the outer peripheral side of the rectangular region. In this case, in the brightness distribution of the light that is emitted from the light source in the outermost peripheral region in the rectangular region and obtained via the diffusion lens, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis of the diffusion lens inclines with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface. In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and it is possible to alleviate the frame-shaped brightness unevenness occurring. In addition, by illuminating the central portion of the illumination region by means of the light sources located in the region inside the outermost peripheral region, it is possible to obtain the above effects while securing the brightness at the central portion. In the above planar light source device, when two directions parallel to the mounting surface and perpendicular to each other are defined as a first direction and a second direction, each of the corner regions may be a region where both-end regions when the rectangular region is divided into three or more regions in the first direction and both-end regions when the rectangular region is divided into three or more regions in the second direction overlie each other. In this case, it is possible to surely alleviate the brightness decline at the four corners of the illumination region by means of the light source located in each corner region while securing the illumination brightness in a region other than the four corners of the illumination region by means of the light source located in a region other than the corner region, and possible to alleviate the brightness unevenness of the entire illumination region. The above planar light source device may be of direct type that illuminates an illumination target from right under in a planar manner by means of the plurality of light sources. In the case of the direct type, the brightness decline easily occurs at the four corners of the illumination region because of the reduction in the number of light sources mounted compared to an edge-light type; accordingly, the structure according to each embodiment of the present invention becomes effective. In the above planar light source device, the plurality of light sources each may be formed of a light emitting diode. In the structure that uses an LED as the light source, the brightness decline easily occurs at the four corners of the illumination region because of the reduction in the number of light sources mounted compared to a structure that uses a tube-like light source (e.g., cold-cathode tube); accordingly, the structure according to each embodiment of the present invention becomes effective. The above planar light source device may further include a reflection sheet that has an opening portion from which each of the plurality of light sources is exposed, is disposed on the bottom plate, and reflects the light emitted from the light source, wherein the reflection sheet may have an edge portion that rises obliquely from the bottom plate on the outer side of the rectangular region. In the structure in which the peripheral portion of the illumination region is illuminated by means of the light that is emitted from the light source and reflected by the edge portion of the reflection sheet, the light source is not disposed in the peripheral portion of the bottom plate to form the edge portion; accordingly, it is possible to reduce the number of light sources mounted, but the light has difficulty in reaching the four corners of the illumination region. Accordingly, the structure according to each embodiment of the present invention, which is able alleviate the brightness decline at the four corners of the illumination region, becomes very effective in the case of achieving reduction in the number of light sources mounted by means of the illumination that uses the edge portion of the reflection sheet. The liquid crystal display device represented in the embodiments of the present invention includes the above planar light source device and a liquid crystal panel that modulates the light supplied from the planar light source device to perform display. In this structure, it is possible to alleviate the brightness declining at the four corners of the screen of the liquid crystal panel and improve the display quality. INDUSTRIAL APPLICABILITY The planar light source device according to the present invention is usable for a backlight of a liquid crystal display device, for example. REFERENCE SIGNS LIST 1 liquid crystal display device 2 liquid crystal panel 3 backlight (planar light source device) 11 a bottom plate 11 a 1 mounting surface 12 LED (light source, light emitting diode) 14 diffusion lens 17 reflection sheet 17 a opening portion 17 b edge portion C central axis D central axis P 1 corner region P 2 outer peripheral region (outermost peripheral region) P 3 central region RA rectangular region Rc central portion Rp peripheral portion
In the present invention, a backlight ( 3 ) serving as a planar light source unit is equipped with: multiple LEDs ( 12 ); and a bottom plate ( 11 a ) having a mounting surface ( 11 a 1 ). The multiple LEDs ( 12 ) are two-dimensionally arranged on the mounting surface ( 11 a 1 ) within a rectangular area (RA) that is smaller than the bottom plate ( 11 a ). In addition, the arrangement density of the LEDs in the rectangular area (RA) is lower at the center part (Rc) than at the peripheral part (Rp). The rectangular area (RA) has a corner area, where at least one LED ( 12 ) is provided, at each of the four corners thereof. The LEDs ( 12 ) positioned in the respective corner areas are installed such that the central axes of the LEDs lean toward the periphery side of the rectangular area (RA) with respect to the direction perpendicular to the mounting surface ( 11 a 1 ).
Summarize the patent document, focusing on the invention's functionality and advantages.
[ "TECHNICAL FIELD The present invention relates to a planar light source device in which a plurality of light sources are disposed two-dimensionally in a rectangular region on a mounting surface and to a liquid crystal display device that includes the planar light source device.", "BACKGROUND ART Conventionally, as a planar light source device that illuminates a liquid crystal panel, a so-called illumination device of direct type, which is disposed right under a rear surface of the liquid crystal panel, is proposed.", "As a light source of such an illumination device, it is possible to use a tube-like light source (e.g., cold-cathode tube lamp) as in patent documents 1 to 3 or use a point light source (e.g., LED (light emitting diode) as in a patent document 4.", "Especially, an LED is advantageous in longevity and low power consumption, and in recent years, many LEDs are used as light sources of illumination devices.", "In the meantime, when humans watch a screen of a liquid crystal panel, they watch more carefully the screen center than the screen peripheral.", "Because of this, in a case of using LEDs as the light source, even if the disposition density of the LEDs is made low at the peripheral portion, visual brightness unevenness is not conspicuous.", "As described above, by partially changing the disposition density of the LEDs, it is possible to secure the brightness of a necessary region (screen center) and achieve low cost by reducing the number of LEDs mounted.", "When changing partially the disposition density of the LEDs, in the patent document 4, as shown in FIG. 25 , LED boards 102 mounting a plurality of LEDs 101 are disposed in parallel, and disposition intervals of the LED boards 102 are partially changed.", "Specifically, in a central portion Rc in an arrangement direction of the LED boards 102 , the interval of neighboring LED boards 102 is made narrow, while in an outside peripheral portion Rp with respect to the central portion Rc in the arrangement direction of the LED boards 102 , the interval of neighboring LED boards 102 is made wide.", "As described above, it is conceivable that by adjusting the interval of the LED boards 102 to change partially the disposition density of the LEDs, it is also possible to easily deal with a size change of an illumination device 100 .", "Besides, in the illumination device in the patent document 4, a reflection sheet 103 is disposed on a bottom plate (mounting surface) of a backlight chassis where the LED board 102 is mounted.", "The reflection sheet 103 has an opening portion for exposing the LED 101 and is disposed on the bottom plate to cover the LED board 102 .", "An edge portion 103 a of the reflection sheet 103 rises obliquely from the bottom plate.", "As described above, by disposing the reflection sheet 103 , even if the LED 101 is not disposed on a peripheral portion of the bottom plate, it is possible to illuminate a screen peripheral portion of a liquid crystal panel by means of light that is emitted from the LED 101 and reflected by the edge portion 103 a of the reflection sheet 103 .", "Accordingly, it is possible to achieve low cost by further reducing the number of LEDs 101 mounted.", "CITATION LIST Patent Literature PLT1: International Publication No. 2009/004840 pamphlet (see claim 1, FIG. 5 and the like).", "PLT2: International Publication No. 2009/004841 pamphlet (see claim 1, FIG. 5 and the like).", "PLT3: International Publication No. 2010/146920 pamphlet (see claim 1, FIG. 11, FIG. 12 and the like).", "PLT4: International Publication No. 2010/146921 pamphlet (see claims 1, 2, paragraphs [0005], [0008], [0035], [0036], FIG. 7 and the like).", "SUMMARY OF INVENTION Technical Problem In the meantime, in FIG. 25 , the LEDs 101 are disposed in a region on the bottom plate where the edge portion 103 a of the reflection sheet 103 does not exist, that is, a rectangular region of V1 (cm) height×H1 (cm) width.", "On the other hand, the bottom plate of the back chassis has a size of V2 (cm) height×H2 (cm) width, where V1<V2, and H1<H2.", "As describe above, because of the reduction in the number of LEDs 101 mounted, if the size (V1×H1) of the disposition region for the LEDs 101 becomes smaller than the size (V2×H2) of the bottom plate and the disposition density of the LEDs 101 in the disposition region becomes lower in the peripheral portion Rp than in the central portion Rc, the light has difficulty in reaching four corners of the screen of the liquid crystal panel from LEDs 101 a to 101 d at four corners of the disposition region.", "As a result of this, as shown in FIG. 26 , a phenomenon easily occurs, in which the brightness in four-corner regions 201 a to 201 d of the screen of the liquid crystal panel declines.", "The present invention has been made to solve the above problems, and it is an object of the present invention to provide: a planar light source device that is able to alleviate the brightness declining at the four corners of an illumination region of an illumination target even in a structure in which a plurality of light sources are disposed such that the disposition density becomes lower in a peripheral portion than in a central portion in a small region that is smaller than a size of a bottom plate;", "and a liquid crystal display device that includes the planar light source device.", "Solution to Problem A planar light source device according to an aspect of the present invention comprises: a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, wherein the rectangular region has, at four corners thereof, corner regions where at least one of the light sources is disposed, and the light source located in each of the corner regions is disposed such that a central axis thereof inclines from a direction perpendicular to the mounting surface toward an outer peripheral side of the rectangular region.", "A planar light source device according to another aspect of the present invention comprises: a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, the planar light source device further comprising a diffusion lens that is disposed correspondingly to each of the plurality of light sources and diffuses light emitted from the light source, wherein the rectangular region has, at four corners thereof, corner regions where at least one of the light sources is disposed, and the diffusion lens corresponding to the light source located in each of the corner regions is disposed such that a central axis thereof is located at a position closer to an outer peripheral side of the rectangular region than a light emitting portion of the light source.", "A planar light source device according to still another aspect of the present invention comprises: a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, the planar light source device further comprising a diffusion lens that is disposed correspondingly to each of the plurality of light sources and diffuses light emitted from the light source, wherein the rectangular region has, at four corners thereof, corner regions where at least one of the light sources is disposed, and the diffusion lens corresponding to the light source located in each of the corner regions is disposed such that a central axis thereof inclines from a direction perpendicular to the mounting surface toward an outer peripheral side of the rectangular region.", "A liquid crystal display device according to still another aspect of the present invention comprises: the above planar light source device, and a liquid crystal panel that modulates light supplied from the planar light source device to perform display.", "Advantageous Effects of Invention According to the present invention, by suitably setting the disposition angles of the light sources located in the four corner regions of the mounting surface, the mounting positions and mounting angles of the diffusion lenses corresponding to the light sources, even in the structure in which to achieve low cost by reduction in the number of the light sources mounted, the disposition region for the light sources is made smaller than the size of the bottom plate and the disposition density of the light sources in the disposition region is made lower in the peripheral portion than in the central portion, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of illumination from the light source in each of the corner regions.", "BRIEF DESCRIPTION OF DRAWINGS FIG. 1A is a cross-sectional view showing a schematic structure of a liquid crystal display device according to an embodiment 1 of the present invention.", "FIG. 1B is a plan view of a backlight of the above liquid crystal display device.", "FIG. 2 is a cross-sectional view of a diffusion lens of the above backlight.", "FIG. 3A is a plan view showing schematically a division example when a rectangular region on which a plurality of LEDs are disposed is divided into a plurality of regions on a bottom plate of the above backlight.", "FIG. 3B is a descriptive view showing an address of each division region in the above division example.", "FIG. 4 is a descriptive view showing schematically LEDs disposed in four corner regions of the above rectangular region and a brightness distribution of light emitted from the LEDs via diffusion lenses.", "FIG. 5A is a plan view showing schematically another division example of the above rectangular region.", "FIG. 5B is a descriptive view showing an address of each division region in the above division example.", "FIG. 6 is a plan view showing another structure of the above backlight.", "FIG. 7 is a plan view showing still another structure of the above backlight.", "FIG. 8 is a plan view showing still another structure of the above backlight.", "FIG. 9 is a plan view of a backlight according to an embodiment 2 of the present invention.", "FIG. 10 is a descriptive view showing schematically LEDs disposed in four corner regions of a rectangular region on which a plurality of LEDs are disposed on a bottom plate of the above backlight and a brightness distribution of light emitted from the LEDs via diffusion lenses.", "FIG. 11 is a plan view showing schematically another division example of the above rectangular region.", "FIG. 12 is a plan view showing another structure of the above backlight.", "FIG. 13 is a plan view showing still another structure of the above backlight.", "FIG. 14 is a plan view showing still another structure of the above backlight.", "FIG. 15 is a plan view of a backlight according to an embodiment 3 of the present invention.", "FIG. 16 is a descriptive view showing schematically LEDs disposed in four corner regions of a rectangular region on which a plurality of LEDs are disposed on a bottom plate of the above backlight and a brightness distribution of light emitted from the LEDs via diffusion lenses.", "FIG. 17 is a plan view showing schematically another division example of the above rectangular region.", "FIG. 18 is a plan view showing another structure of the above backlight.", "FIG. 19 is a plan view showing still another structure of the above backlight.", "FIG. 20 is a plan view showing still another structure of the above backlight.", "FIG. 21 is a cross-sectional view showing another disposition example of an LED and a diffusion lens in a corner region of the above rectangular region.", "FIG. 22 is a cross-sectional view showing still another disposition example of an LED and a diffusion lens in a corner region of the above rectangular region.", "FIG. 23 is a cross-sectional view showing still another disposition example of an LED and a diffusion lens in a corner region of the above rectangular region.", "FIG. 24 is a cross-sectional view showing still another disposition example of an LED and a diffusion lens in a corner region of the above rectangular region.", "FIG. 25 is a plan view showing a structure of a conventional backlight.", "FIG. 26 is a plan view showing schematically a display screen of a liquid crystal panel illuminated by the backlight.", "DESCRIPTION OF EMBODIMENTS Embodiment 1 An embodiment 1 of the present invention is described based on drawings as follows.", "In the meantime, there is a case where structures common to each embodiment are indicated by the same member numbers and description of them is skipped.", "FIG. 1A is a cross-sectional view showing a schematic structure of a liquid crystal display device 1 according to the present embodiment, and FIG. 1B is a plan view of a backlight 3 of the liquid crystal display device 1 .", "In the meantime, in FIG. 1B , for the sake of convenience, illustration of a diffusion plate 15 and an optical sheet 16 described later is skipped.", "As shown in these drawings, the liquid crystal display device 1 has a liquid crystal panel 2 and a backlight 3 .", "The liquid crystal panel 2 is a liquid crystal display element that modulates light supplied from the backlight 3 to display an image, and composed by sandwiching a liquid layer by means of a pair of boards.", "One board is provided with a source wiring and a gate wiring disposed to cross each other at right angles, a switching element (e.g., TFT: Thin Film Transistor) that performs ON/OFF of driving of a pixel enclosed by the source wiring and the gate wiring adjacent to each other, a pixel electrode connected to the switching element and the like.", "The other board is provided with a color filter formed of color filters of R (red), G (green), and B (blue) disposed correspondingly to each pixel, a common electrode common to each pixel and the like.", "Besides, a side of each board facing the liquid crystal layer is provided with an orientation film that orients liquid crystal molecules, while an outer side (opposite to the liquid crystal layer) of each board is provided with a light polarization plate that transmits predetermined polarized light only.", "The backlight 3 is a planar light source device (illumination device) of direct type that is disposed right under a rear surface of the liquid crystal panel 2 and illuminates the liquid crystal panel 2 in a planar manner.", "The backlight 3 includes a backlight chassis 11 , LEDs 12 as a plurality of light sources, an LED board 13 , a diffusion lens 14 , a diffusion plate 15 , an optical sheet 16 , a reflection sheet 17 , and a not-shown circuit board.", "The above circuit board is a circuit board that controls light emission from the LED 12 , but may include a circuit board for driving the liquid crystal panel 2 and other boards (power source board, control board).", "The backlight chassis 11 is a chassis member that is formed by bending a sheet metal into a predetermined shape, has a bottom plate 11 a and a side plate 11 b .", "The bottom plate 11 a is formed into a rectangular shape when viewing from top, and on one surface of which (surface facing the liquid crystal panel 2 ) the plurality of LEDs 12 are mounted via the LED board 13 .", "Hereinafter, this surface is called a mounting surface 11 a 1 on which the plurality of LEDs 21 are mounted.", "The side plate 11 b is connected to an outer peripheral portion (four side edge portions of the bottom plate 11 a ) of the bottom plate 11 a to rise substantially upright from the bottom plate 11 a. The LEDs 12 are each a light emitting diode (point light source) that has a light emitting portion 12 a (see FIG. 2 ) and mouthed in a line on the LED board 13 as a mounting board.", "A plurality of the LED boards 13 are disposed in parallel on the bottom plate 11 a .", "In this way, the plurality of LEDs 12 are disposed two-dimensionally on the bottom plate 11 a .", "In the present embodiment, because the reflection sheet 17 described later is provided with an edge portion 17 b , on the bottom plate 11 a , a disposition region for the LEDs 12 is a rectangular region RA smaller than a size of the bottom plate 11 a. Here, two directions parallel to the mounting surface 11 a 1 of the bottom plate 11 a and perpendicular to each other are defined as an H direction (first direction) and a V direction (second direction), respectively.", "In the meantime, the H direction corresponds to, for example, a long-edge direction of the rectangular region RA, while the V direction corresponds to a short-edge direction of the rectangular region.", "The size of the rectangular region RA is H1 (cm)×V1 (cm), while the size of the bottom plate 11 a is H2 (cm)×V2 (cm), where H1<H2, V1<V2.", "As described above, the rectangular region RA is one size smaller than the size of the bottom plate 11 a. Besides, on the bottom plate 11 a , the disposition interval of the LED boards 13 is narrow in a central portion Rc in the arrangement direction of the LED boards 13 and wide in an outer peripheral portion Rp with respect to the central portion Rc in the arrangement direction.", "As a result of this, the disposition density of the LEDs 12 is high in the central portion Rc of the rectangular region RA and low in the peripheral portion Rp.", "As described above, by partially changing the disposition density of the LEDs 12 , it is possible to secure an illumination brightness in a necessary region (central region Rc) and to achieve low cost by reducing the number of LEDs 12 mounted as a whole.", "Besides, by adjusting the disposition interval of the LED boards 13 to partially change the disposition density of the LEDs 12 , it is also possible to easily deal with a size change of the backlight 3 .", "The diffusion lens 14 is disposed on the LED board 13 correspondingly to each of the plurality of LEDs 12 and diffuses the light emitted from each LED 12 .", "In the meantime, a detailed structure of the diffusion lens 14 is described later.", "By disposing the diffusion lens 14 , the light from the LED 12 is diffused by the diffusion lens 14 ;", "accordingly, even in a case where the interval between neighboring LEDs 12 is large, dot-like unevenness becomes unlikely to occur in a brightness distribution by each LED 12 .", "As a result of this, it is possible to achieve low cost by further reducing the number of LEDs 12 mounted.", "In the meantime, in a case where it is possible to amply reduce the number of LEDs 12 mounted by adjusting the above disposition interval of the LED boards 13 , it is also possible to employ a structure in which the diffusion lens 14 is not disposed.", "The diffusion plate 15 further diffuses and averages the light emitted from each LED 12 via the diffusion lens 14 , is formed into a flat plate shape and disposed at a position closer to the liquid crystal panel 2 than the diffusion lens 14 .", "The optical sheet 16 outputs the light, which passes through the diffusion plate 15 , as planar light and is composed to include a lens sheet, a prism sheet, a retroreflection sheet and the like.", "Respective end portions of the diffusion plate 15 and optical sheet 16 are supported by the side plate 11 b of the backlight chassis 11 via end portions of the reflection sheet 17 .", "The reflection sheet 17 has an opening portion 17 a from which each LED 12 is exposed, is disposed on the bottom plate 11 a to cover the LED board 13 , and reflects the light, which is emitted from the LED 12 and directly enters the reflection sheet, and the light, which is emitted from the LED 12 and reflected by the diffusion plate 15 and the like to enter the reflection sheet, again to the liquid crystal panel 2 .", "In this way, it is possible to improve use efficiency of the light emitted from the LED 12 .", "The reflection sheet 17 has the edge portion 17 b that rises obliquely from the bottom plate 11 a outside the rectangular region RA.", "In other words, the edge portion 17 b is located to surround the rectangular region RA.", "An end portion (outer peripheral portion) of the edge portion 17 b is supported from under by the side plate 11 b of the backlight chassis 11 .", "By disposing the reflection sheet 17 , even if the LEDs 12 are not disposed on the outer peripheral portions of the bottom plate 11 a , it is possible to illuminate screen peripheral portions of the liquid crystal panel 2 by means of the light that is emitted from the LEDs 12 and reflected by the edge portion 17 b of the reflection sheet 17 .", "Accordingly, it is possible to achieve low cost by further reducing the number of LEDs 12 mounted all the more because the LEDs 12 are not disposed on the peripheral portions of the bottom plate 11 a. Next, details of a structure of the above diffusion lens 14 are described.", "FIG. 2 a cross-sectional view of the diffusion lens 14 .", "The diffusion lens 14 has a lens portion 14 a and a plurality of leg portions 14 b (e.g., three) that support the lens portion 14 a on the LED board 13 , and is formed into a rotator shape (circular shape when viewing from top) as a whole.", "The leg portions 14 b are disposed at an equal interval (e.g., angle interval of 120°) in a direction along an outer circumference of the lens portion 14 a , and mounted at predetermined of the LED board 13 positions by means of an adhesive (not shown), for example.", "By adjusting a length of each leg portion 14 b , it is possible to adjust a mounting angle of the diffusion lens 14 to the LED board 13 ;", "however, in the present embodiment, the lengths of the leg portions 14 b are all the same.", "As a result of this, a central axis (optical axis) C of the diffusion lens 14 is perpendicular to the mounting surface 11 a of the bottom plate 11 a. The lens portion 14 a has a light output surface (upper surface) 14 c and a lower surface 14 d .", "The light output surface 14 c is formed into a concave shape recessed toward the LED 12 at a central region close to the central axis C and formed into a convex shape raised oppositely to the LED 12 in an outer circumferential region with respect to the central region in a lens radial direction.", "Besides, in the lower surface 14 d , a portion opposite to the LED 12 has a concave portion 14 e that is recessed oppositely to the LED 12 .", "According to such structure of the diffusion lens 14 , the light emitted from the LED 12 is changed (diffused) in travelling direction to the outside by the concave portion 14 e and the light output surface 14 c , so that a light expansion angle becomes large.", "In the meantime, the shapes of the light output surface 14 c and lower surface 14 d of the diffusion plate 14 are not limited to the above shapes, and whatever shapes may be employed if the shapes diffuse (enlarge the light expansion angle) the light emitted from the LED 12 .", "Accordingly, for example, it is also possible to compose the diffusion lens 14 without disposing the concave portion recessed toward the LED 12 at the central region of the light output surface 14 c , and also possible to compose the diffusion lens 14 without forming the concave portion 14 e in the lower surface 14 d. Next, a structure, which alleviates a brightness decline at the screen four corners of the liquid crystal panel 2 as an illumination target, is described.", "FIG. 3A is a plan view showing schematically a division example when the rectangular region RA on which the plurality of LEDs 12 are disposed is divided into a plurality of regions on the bottom plate 11 a , and FIG. 3B is a descriptive view showing addresses of the plurality of divided regions (hereinafter, also called a division region).", "In FIG. 3A , the rectangular region RA is divided into, for example, 7 regions in the H direction (long-edge direction) and into, for example, 4 regions in the V direction (short-edge direction);", "accordingly, FIG. 3B shows a total of 28 regions R ij , where i is an integer of 1 to 4 and corresponds to a number of a row parallel to the H direction, while j is an integer of 1 to 7 and corresponds to a number of a column parallel to the V direction.", "Here, for the sake of convenience for the following description, in the rectangular region RA, regions R 11 ·R 17 ·R 41 ·R 47 located in the four corners are called corner regions P 1 .", "Besides, in the rectangular region RA, regions located in outermost peripheral portions including the four corner regions P 1 , namely, regions R 11 to R 17 , regions R 21 ·R 27 , regions R 31 ·R 37 , and regions R 41 to R 47 are called outer peripheral regions P 2 .", "Further, in the rectangular region RA, the remaining regions except for the corner regions P 1 and outer peripheral regions P 2 , namely, regions R 22 to R 26 and regions R 32 to R 36 located (surrounded by the outer peripheral regions P 2 ) inside the outer peripheral regions P 2 are called central regions P 3 .", "In FIG. 3B , to facilitate the identification of the corner regions P 1 , outer peripheral regions P 2 and central regions P 3 , these three kinds of regions are indicated by symbols of ∘, Δ, and □, respectively.", "In the present embodiment, one LED 12 is disposed in each of the four corner regions P 1 .", "Besides, the above diffusion lens 14 is disposed correspondingly to each LED 12 ;", "accordingly, one diffusion lens 14 is disposed in each corner region P 1 .", "FIG. 4 shows schematically the LEDs 12 disposed in the four corner regions P 1 and a brightness distribution of the light emitted from the LEDs 12 via the diffusion lenses 14 .", "In the present embodiment, the LED 12 located in each corner region P 1 is disposed such that a central axis D thereof inclines from a direction perpendicular to the bottom plate 11 a (mounting surface 11 a 1 ) toward the outer peripheral side of the rectangular region RA, especially toward each apex of the four corners of the rectangular region RA.", "In the meantime, in FIG. 3A , an arrow attached to the LED 12 indicates the direction in which the central axis D of the LED 12 inclines, and other drawings appearing in the present embodiment are illustrated in the same way as this.", "Besides, as to the LED 12 with no arrow attached, the central axis D is in the direction perpendicular to the bottom plate 11 a. In the meantime, the central axis D of the LED 12 has the same meaning as a central axis (optical axis) of the light flux emitted from the LED 12 .", "In other words, an axis, which passes through the light emitting portion 12 a of the LED 12 and a position where intensity (radiation intensity) of the light emitted from the LED 12 becomes the highest, is defined as the central axis D of the LED 12 .", "Here, in the present embodiment, to incline the central axis D of the LED 12 as described above, the LED 12 is mounted on the LED board 13 via a support member 18 .", "The support member 18 is formed into a triangle pole shape that has a right triangle in cross section and disposed sideways on the LED board 13 .", "Accordingly, by disposing the LED 12 onto a surface of the support member 18 inclined by an acute angle to the LED board 13 and disposing the support member 18 onto the LED board 13 such that a normal of the surface of the support member 18 faces each apex of the four corners of the rectangular region RA, it is possible to incline the central axis D of the LED 12 as described above.", "As described above, in the four corner regions P 1 , by disposing the LED 12 such that the central axis D of the LED 12 inclines toward the outer peripheral side of the rectangular region RA, as shown in FIG. 4 , in the brightness distribution of the light emitted from each LED 12 in each corner region P 1 , it is possible to raise the illumination brightness on the side (outer peripheral side of the rectangular region RA) toward which the central axis D inclines with respect to an axis (e.g., central axis C of the diffusion lens 14 ) that passes through the LED 12 (light emitting portion 12 a ) and is perpendicular to the mounting surface 11 a 1 .", "In this way, even in the structure in which low cost is achieved by reduction in the number of LEDs 12 mounted, namely, even in the structure in which the disposition region for the LEDs 12 is made smaller than the size of the bottom plate 11 a and the disposition density of the LEDs 12 in the disposition region is made lower in the peripheral portion Rp than in the central portion Rc, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 .", "Especially, in a case where the number of LEDs 12 mounted is further reduced, or in a case where thickness reduction of the backlight 3 is pursued, the brightness at the four corners of the illumination region easily declines;", "accordingly, as described above, the structure in which the LED 12 inclines to alleviate the brightness decline at the four corners becomes very effective.", "Besides, in the liquid crystal display device 1 that illuminates the liquid crystal panel 2 by means of the backlight 3 having the above structure, it is possible to alleviate the brightness declining at the four corners of the screen of the liquid crystal panel 2 ;", "accordingly, it is possible to improve display quality.", "Besides, the LED 12 located in each corner region P 1 is disposed such that the central axis D thereof inclines toward each apex of the four corners of the rectangular region RA;", "accordingly, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 .", "Accordingly, it is possible to surely alleviate the brightness declining at the four corners of the illumination region.", "In the meantime, the above effects are obtainable even in a case where the diffusion lens 14 is not disposed over the light emitting side of the LED 12 .", "However, in the case where the diffusion lens 14 is disposed, the light from the LED 12 is diffused by the diffusion lens 14 , so that the brightness decline at the four corners of the illumination region becomes less conspicuous;", "accordingly, in this point, it is desirable to employ the structure in which the diffusion lens 14 is disposed.", "Besides, in the backlight 3 of direct type that illuminates the liquid crystal panel 2 from right under, brightness unevenness (e.g., brightness decline at the four corners of the screen) easily occurs in the liquid crystal panel 2 compared to an edge-light type that shines light onto an end surface of a light guide plate to illuminate the liquid crystal panel 2 in a planar manner.", "Accordingly, the above structure, which alleviates the brightness decline at the four corners of the screen by disposing and inclining the LED 12 in each corner region P 1 , becomes very effective.", "Besides, in the case where the LED 12 is used as the light source of the backlight 3 , the brightness decline due to the reduction in the number of light sources mounted easily occurs at the four corners of the screen compared to a case where a tube-like light source (e.g., cold-cathode tube) is used.", "Accordingly, in the case where the LED 12 is used as the light source, the above structure, which alleviates the brightness decline at the four corners of the screen by disposing and inclining the LED 12 in each corner region P 1 , becomes very effective.", "Besides, in the case where the diffusion sheet 17 is disposed in the backlight 3 , as described above, it is possible to illuminate the screen peripheral portion of the liquid crystal panel 2 by means of the light reflected by the edge portion 17 b of the reflection sheet 17 .", "However, in this case, the LED 12 is not disposed on the peripheral portion of the bottom plate 11 a ;", "accordingly, it is possible to reduce the number of LEDs 12 mounted, but the light has difficulty in reaching the four corners of the screen of the liquid crystal panel 2 .", "Accordingly, in the case where the liquid crystal panel 2 is illuminated by means of the edge portion 17 b of the reflection sheet 17 (case where the reduction in the number of LEDs 12 mounted is achieved), to alleviate the brightness decline at the four corners of the screen, the structure which inclines the LED 12 in each corner region P 1 becomes very effective.", "In the meantime, hereinbefore, the structure is described, in which one LED 12 is disposed in each division region of the rectangular region RA and one LED 12 in the corner region P 1 is inclined;", "however, a structure may be employed, in which a plurality of LEDs 12 are disposed in each division region and the plurality of LEDs 12 in the corner region P 1 are inclined.", "In other words, in the case where the total number of LEDs 12 is constant, a structure may be employed, which relatively reduces the number of division regions, increases the number of LEDs 12 disposed in one division region, and inclines the plurality of LEDs 12 in the corner region P 1 .", "Hereinafter, this point is described more specifically.", "FIG. 5A is a plan view showing schematically another division example of the rectangular region RA, and FIG. 5B is a descriptive view showing an address of each division region.", "In FIG. 5A , the rectangular region RA is divided into, for example, 3 regions in the H direction and into, for example, 3 regions in the V direction;", "accordingly, FIG. 5B shows a total of 9 regions R ij , where i is an integer of 1 to 3 and corresponds to a number of a row parallel to the H direction, while j is an integer of 1 to 3 and corresponds to a number of a column parallel to the V direction.", "Here, in the rectangular region RA, regions R 11 ·R 13 ·R 31 ·R 33 located in the four corners are called the corner regions P 1 .", "Besides, in the rectangular region RA, regions located in the outermost peripheral portions including the four corner regions P 1 , namely, regions R 11 to R 13 , regions R 21 ·R 23 , regions R 31 to R 33 are called the outer peripheral regions P 2 .", "Further, in the rectangular region RA, regions except for the corner regions P 1 and outer peripheral regions P 2 , namely, a regions R 22 located (surrounded by the outer peripheral regions P 2 ) inside the outer peripheral regions P 2 is called the central regions P 3 .", "In FIG. 5B , to facilitate the identification of the corner regions P 1 , outer peripheral regions P 2 and central regions P 3 , these three kinds of regions are indicated by symbols of ∘, Δ, and □, respectively.", "In the case where the total number of LEDs 12 is the same as in FIG. 3A and FIG. 3B and the number of division regions in the rectangular region RA is reduced as in FIG. 5A and FIG. 5B , the number of LEDs 12 disposed in one division region increases from the case of FIG. 3A and FIG. 3B .", "In this example, two LEDs 12 are disposed in each corner region P 1 .", "In the meantime, the above diffusion lens 14 is disposed correspondingly to each LED 12 ;", "accordingly, also two diffusion lenses 14 are disposed in each corner region P 1 .", "As described above, by disposing the plurality of LEDs 12 in the corner regions P 1 such that the central axis D inclines toward the outer peripheral side of the rectangular region RA, the amount of the light supplied to the four corners of the illumination region by the plurality of LEDs 12 in the corner regions P 1 increases compared to the structure in which one LED 12 is inclined.", "Accordingly, it is possible to more alleviate the brightness decline at the four corners of the illumination region.", "From the above description, it can be said preferable if the rectangular region RA in which the LEDs 12 are disposed has, at the four corners, the corner regions P 1 in each of which at least one LED 12 is disposed and the LED 12 located in each corner region P 1 is disposed such that the central axis D thereof inclines toward the outer peripheral side of the rectangular region RA.", "Besides, to secure a high illumination brightness at the central portion of the illumination region while alleviating the brightness decline at the four corners of the illumination region by means of the LEDs 12 in the four corner regions P 1 , it is necessary to illuminate the central portion of the illumination region by means of LEDs 12 in the central region of the rectangular region RA while preventing the central axes D of the LEDs 12 in the central region from inclining toward the outer peripheral side of the rectangular region RA.", "At this time, for example, if the rectangular region RA is divided into a total of four regions with divided into 2 regions in the H direction and divided into 2 regions in the V direction, all of these four regions become the corner regions P 1 that include each apex of the four corners, and the central axes D of all the LEDs 12 incline toward the outer peripheral side.", "In other words, in this case, it is impossible to allow a region, in which the central axis D of the LED 12 does not incline, to exist in the rectangular region RA.", "Accordingly, in the present embodiment, by dividing the rectangular region RA into at least 9 regions with divided into 3 or more regions in the H direction and divided into 3 or more regions in the V direction, it is possible to surely alleviate the brightness decline at the four corners of the illumination region by means of the LED 12 in each corner region P 1 while surely achieving improvement in the illumination brightness at the central portion of the illumination region by means of the LED 12 located in a region (e.g., central region P 3 ) except for each corner region P 1 .", "At this time, each corner region P 1 becomes a region where both-end regions when the rectangular region RA is divided into three or more regions in the H direction and both-end regions when the rectangular region RA is divided into three or more regions in the V direction overlie each other.", "Besides, hereinbefore, the example is described, in which each central axis D of the LED 12 in each corner region inclines toward each corresponding apex of the four corners from the direction perpendicular to the bottom plate 11 a (mounting surface 11 a );", "however, if the central axis D inclines toward the outer peripheral side of the rectangular region RA, the inclination direction is not limited to the direction toward each apex of the four corners.", "FIG. 6 is a plan view showing another structure of the backlight 3 , and FIG. 7 is a plan view showing still another structure of the backlight 3 .", "As shown in FIG. 6 and FIG. 7 , the LED 12 in each corner region P 1 may be disposed such that the central axis D thereof inclines from the direction perpendicular to the bottom plate 11 a (mounting surface 11 a 1 ) toward a long edge or a short edge of the rectangular region RA.", "Besides, FIG. 8 is a plan view showing still another structure of the backlight 3 .", "The LEDs 12 located in the outer peripheral region P 2 (see FIG. 3B , FIG. 5B ) may be disposed such that each central axis D inclines from the direction perpendicular to the bottom plate 11 a (mounting surface 11 a 1 ) toward the outer peripheral side (long edge, short edge) of the rectangular region RA.", "In this case, in the brightness distribution of the light emitted from the LED 12 in the outer peripheral region P 2 , it is possible to raise the brightness on the side (outer peripheral side of the rectangular region RA) toward which the central axis D inclines with respect to the axis that passes through the LED 12 and is perpendicular to the mounting surface 11 a 1 .", "In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and for example, it is possible to alleviate frame-shaped brightness unevenness occurring on the display screen of the liquid crystal panel 2 .", "Accordingly, it is possible to further reduce the number of light sources in the outer peripheral region.", "In addition, by illuminating the central portion of the illumination region by means of the LEDs 12 located in the region (central region P 3 ) inside the outer peripheral region P 2 , it is possible to obtain the above effects while securing the brightness at the central portion.", "Embodiment 2 An embodiment 2 of the present invention is described based on drawings as follows.", "FIG. 9 is a plan view of the backlight 3 according to the present embodiment.", "In the meantime, in FIG. 9 , for the sake of convenience, the illustration of the diffusion plate 15 and optical sheet 16 is skipped.", "In the present embodiment, instead of inclining the LED 12 located in each corner region P 1 of the rectangular region RA in the structure according to the embodiment 1, the position of the diffusion lens 14 corresponding to the above LED 12 is deviated with respect to the LED 12 .", "In more detail, the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 is disposed such that the central axis C thereof inclines toward the outer peripheral side of the rectangular region RA, especially toward each apex of the four corners of the rectangular region RA with respect to the light emitting portion 12 a of the LED 12 .", "In the meantime, in FIG. 9 , an arrow attached to the diffusion lens 14 indicates the direction in which the diffusion lens 14 deviates with respect to the LED 12 , and other drawings appearing in the present embodiment are illustrated in the same way as this.", "Besides, as to the diffusion lens 14 with no arrow attached, the central axis C does not deviate (passes through the light emitting portion 12 a ) from the light emitting portion 12 a of the LED 12 .", "FIG. 10 shows schematically the LEDs 12 disposed in the four corner regions P 1 and a brightness distribution of the light emitted from the LEDs 12 via the diffusion lenses 14 .", "In the present embodiment, the central axis C of the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portion 12 a of the LED 12 , so that in the above brightness distribution, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 deviates) of the rectangular region RA compared to the case where the diffusion lens 14 is not deviated.", "In this way, even in the structure in which to achieve low cost by reduction in the number of LEDs 12 mounted, the disposition region for the LEDs 12 is made smaller than the size of the bottom plate 11 a and the disposition density of the LEDs 12 in the disposition region is made lower in the peripheral portion Rp than in the central portion Rc, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 .", "Especially, in the corner region P 1 , the diffusion lens 14 is disposed such that the central axis C of the diffusion lens 14 is located at a position closer to each apex of the four corners of the rectangular region RA than the light emitting portion 12 a of the LED 12 ;", "accordingly, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 and to surely alleviate the brightness declining at the four corners of the illumination region.", "Here, FIG. 11 is a plan view showing schematically another division example of the rectangular region RA of the backlight 3 according to the present embodiment.", "In the meantime, in FIG. 11 , for the sake of convenience, the illustration of the diffusion plate 15 and optical sheet 16 is skipped.", "As shown in the drawing, to dispose a plurality of the LEDs 12 in one division region, the rectangular region RA on the bottom plate 11 a may be divided into 3×3 regions, namely, a total of 9 regions, and the diffusion lenses 14 corresponding to the plurality of LEDs 12 (two in FIG. 11 ) in each corner region P 1 may be disposed such that the central axes C are located at positions closer to the outer peripheral side of the rectangular region RA than the light emitting portions 12 a of the LEDs 12 .", "In this case, the amount of the light that is emitted from the LEDs 12 in the corner regions P 1 and supplied to the four corners of the illumination region via the diffusion lenses 14 increases compared to the structure in which only one diffusion lens 14 in the corner region P 1 is deviated toward the outer peripheral side.", "Accordingly, it is possible to more alleviate the brightness decline at the four corners of the illumination region.", "From the above description, it can be said preferable if the rectangular region RA in which the LEDs 12 are disposed has, at the four corners, the corner regions P 1 in each of which at least one LED 12 is disposed and the diffusion lens 14 corresponding to the LED 12 located in each corner region P 1 is disposed such that the central axis C thereof is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portion 12 a of the LED 12 .", "Besides, if the diffusion lens 14 is disposed in each corner region P 1 such that the central axis C of the diffusion lens 14 is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portions 12 a of the LEDs 12 , the direction, in which the diffusion lens 14 deviates with respect to the light emitting portion 12 a , is not limited to the direction toward each apex of the four corners.", "FIG. 12 is a plan view showing another structure of the backlight 3 according to the present embodiment, and FIG. 13 is a plan view showing still another structure of the backlight 3 .", "As shown in FIG. 12 and FIG. 13 , the diffusion lens 14 in each corner region P 1 may be disposed such that the central axis C thereof is located at a position closer to the long edge or the short edge of the rectangular region RA than the light emitting portion 12 a. Besides, FIG. 14 is a plan view showing still another structure of the backlight 3 .", "The diffusion lens 14 corresponding to the LED 12 located in the outer peripheral region P 2 (see FIG. 3B , FIG. 5B ) may be disposed such that the central axis C is located at a position closer to the outer peripheral side (long edge, short edge) of the rectangular region RA than the light emitting portions 12 a. In this case, in a brightness distribution of the light that is emitted from the LED 12 in the outer peripheral region P 2 and obtained via the diffusion lens 14 , it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 deviates) of the rectangular region RA with respect to the axis (e.g., central axis D) that passes through the light emitting portion 12 a of the LED 12 and is perpendicular to the mounting surface 11 a 1 compared to the case where the diffusion lens 14 is not deviated.", "In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and it is possible to alleviate the frame-shaped brightness unevenness occurring on the display screen of the liquid crystal panel 2 , for example.", "Accordingly, it is possible to further reduce the number of light sources in the outer peripheral region.", "In addition, by illuminating the central portion of the illumination region by means of the LEDs 12 located in the region (central region P 3 ) inside the outer peripheral region P 2 , it is possible to obtain the above effects while securing the brightness at the central portion.", "Embodiment 3 An embodiment 3 of the present invention is described based on drawings as follows.", "FIG. 15 is a plan view of the backlight 3 according to the present embodiment.", "In the meantime, in FIG. 15 , for the sake of convenience, the illustration of the diffusion plate 15 and optical sheet 16 is skipped.", "In the present embodiment, instead of inclining the LED 12 located in each corner region P 1 of the rectangular region RA in the structure according to the embodiment 1, the diffusion lens 14 corresponding to the above LED 12 is inclined and disposed.", "In more detail, the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA, especially toward each apex of the four corners of the rectangular region RA.", "Besides, in the present embodiment, the above diffusion lens 14 is disposed such that the central axis C thereof passes through the light emitting portion 12 a of the LED 12 .", "In the meantime, in FIG. 15 , an arrow attached near the diffusion lens 14 indicates a direction in which the central axis C of the diffusion lens 14 inclines from the direction perpendicular to the mounting surface 11 a 1 , and other drawings appearing in the present embodiment are illustrated in the same way as this.", "Besides, as to the diffusion lens 14 with no arrow attached, the central axis C does not incline (direction perpendicular to the mounting surface 11 a 1 ).", "Here, in the present embodiment, to incline the central axis C of the diffusion lens 14 as described above, the length of the leg portion 14 b of the diffusion lens 14 is adjusted.", "For example, by forming the length of the leg portion 14 b of the plurality of leg portions 14 b furthest from the outer peripheral side of the rectangular region RA to be longer than the leg portion 14 b closest to the outer peripheral side of the rectangular region RA, it is possible to incline the central axis C from the direction perpendicular to the bottom plate 11 a toward the above outer peripheral side.", "In the meantime, also as to the leg portions 14 b other than the above leg portion, the length may be suitably adjusted in accordance with the inclination direction and inclination angle of the central axis C. FIG. 16 shows schematically the LEDs 12 disposed in the four corner regions P 1 and a brightness distribution of the light emitted from the LEDs 12 via the diffusion lenses 14 .", "In the present embodiment, the central axis C of the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 inclines to lean from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA, so that in the above brightness distribution, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 inclines) of the rectangular region RA with respect to the axis (e.g., central axis D of the LED 12 ) that passes through the light emitting portion 12 a and is perpendicular to the mounting surface 11 a 1 compared to the case where the diffusion lens 14 does not incline.", "In this way, even in the structure in which to achieve low cost by reduction in the number of LEDs 12 mounted, the disposition region for the LEDs 12 is made smaller than the size of the bottom plate 11 a and the disposition density of the LEDs 12 in the disposition region is made lower in the peripheral portion Rp than in the central portion Rc, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 .", "Especially, in the corner region P 1 , the diffusion lens 14 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward each apex of the four corners of the rectangular region RA;", "accordingly, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the LED 12 in each corner region P 1 and to surely alleviate the brightness declining at the four corners of the illumination region.", "Here, FIG. 17 is a plan view showing schematically another division example of the rectangular region RA of the backlight 3 according to the present embodiment.", "In the meantime, in FIG. 17 , for the sake of convenience, the illustration of the diffusion plate 15 and optical sheet 16 is skipped.", "As shown in the drawing, to dispose a plurality of the LEDs 12 in one division region, the rectangular region RA on the bottom plate 11 a may be divided into a plurality of regions (e.g., a total of 9 regions of 3×3) and the diffusion lenses 14 corresponding to the plurality of LEDs 12 (two in FIG. 17 ) in each corner region P 1 may be disposed such that the central axes C incline from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA.", "In this case, the amount of the light that is emitted from the LEDs 12 in the corner region P 1 and supplied to the four corners of the illumination region via the diffusion lenses 14 increases compared to the structure in which only one diffusion lens 14 in the corner region P 1 is inclined toward the outer peripheral side.", "Accordingly, it is possible to more alleviate the brightness decline at the four corners of the illumination region.", "From the above description, it can be said preferable if the rectangular region RA in which the LEDs 12 are disposed has, at the four corners, the corner regions P 1 in each of which at least one LED 12 is disposed and the diffusion lens 14 corresponding to the LED 12 located in each corner region P 1 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA.", "Besides, in each corner region P 1 , if the diffusion lens 14 is disposed such that the central axis C of the diffusion lens 14 inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA, the direction in which the diffusion lens 14 inclines is not limited to a direction toward each apex of the four corners of the rectangular region RA.", "FIG. 18 is a plan view showing another structure of the backlight 3 , and FIG. 19 is a plan view showing still another structure of the backlight 3 .", "As shown in FIG. 18 and FIG. 19 , the diffusion lens 14 in each corner region P 1 may be disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the long edge or the short edge of the rectangular region RA.", "Besides, FIG. 20 is a plan view showing still another structure of the backlight 3 .", "The diffusion lens 14 corresponding to the LED 12 located in the outer peripheral region P 2 (see FIG. 3B , FIG. 5B ) may be disposed such that the central axis C inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side (long edge, short edge) of the rectangular region RA.", "In this case, in a brightness distribution of the light that is emitted from the LED 12 in the outer peripheral region P 2 and obtained via the diffusion lens 14 , it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 inclines) of the rectangular region RA with respect to the axis (e.g., central axis D of the LED 12 ) that passes through the light emitting portion 12 a and is perpendicular to the mounting surface 11 a 1 compared to the case where the diffusion lens 14 does not incline.", "In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and it is possible to alleviate the frame-shaped brightness unevenness occurring on the display screen of the liquid crystal panel 2 , for example.", "Accordingly, it is possible to further reduce the number of light sources in the outer peripheral region.", "In addition, by illuminating the central portion of the illumination region by means of the LEDs 12 located in the region (central region P 3 ) inside the outer peripheral region P 2 , it is possible to obtain the above effects while securing the brightness at the central portion.", "[Supplement] It is of course possible to compose the backlight 3 and the liquid crystal display device 1 by suitably combining the above embodiments.", "Hereinafter, combinations of the embodiments are described.", "FIG. 21 is a cross-sectional view showing another disposition example of the LED 12 and diffusion lens 14 in the corner region P 1 of the rectangular region RA.", "As shown in the drawing, the backlight 3 may have a structure obtained by combining the embodiments 1 and 2.", "In other words, the backlight 3 may be structured in such a way that (1) the LED 12 in each corner region P 1 is disposed such that the central axis D thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA and (2) the diffusion lens 14 in each corner region P 1 is disposed such that the central axis C thereof is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portion 12 a of the LED 12 .", "In this structure, in the brightness distribution of the light that is emitted from the LED 12 in each corner region P 1 and obtained via the diffusion lens 14 , even in a case where the inclination angle (inclination angle to the direction perpendicular to the mounting surface 11 a 1 ) of the central axis D of the LED 12 is small, because of the above disposition of the diffusion lens 14 , it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 deviates) of the rectangular region RA with respect to the axis that passes through the light emitting portion 12 a and is perpendicular to the mounting surface 11 a 1 .", "In this way, even in the case where the inclination angle of the central axis D of the LED 12 is small, it is possible to surely obtain the effect of alleviating the brightness declining at the four corners of the illumination region.", "Besides, in a case where the inclination angle of the central axis D of the LED 12 is enlarged, it is possible to further alleviate the brightness declining at the four corners of the illumination region in cooperation with the above disposition of the diffusion lens 14 .", "Besides, FIG. 22 is a cross-sectional view showing still another disposition example of the LED 12 and diffusion lens 14 in the corner region P 1 of the rectangular region RA.", "As shown in the drawing, the backlight 3 may have a structure obtained by combining the embodiments 1 and 3.", "In other words, the backlight 3 may be structured in such a way that (1) the LED 12 in each corner region P 1 is disposed such that the central axis D thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA and (2) the diffusion lens 14 in each corner region P 1 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA.", "In this structure, in the brightness distribution of the light that is emitted from the LED 12 in each corner region P 1 and obtained via the diffusion lens 14 , even in a case where the inclination angle of the central axis D of the LED 12 is small, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens 14 inclines) of the rectangular region RA with respect to the axis that passes through the light emitting portion 12 a and is perpendicular to the mounting surface 11 a 1 .", "In this way, even in the case where the inclination angle of the central axis D of the LED 12 is small, it is possible to surely obtain the effect of alleviating the brightness declining at the four corners of the illumination region.", "Besides, in a case where the inclination angle of the central axis D of the LED 12 is enlarged, it is possible to further alleviate the brightness declining at the four corners of the illumination region in cooperation with the above disposition of the diffusion lens 14 .", "Besides, FIG. 23 is a cross-sectional view showing still another disposition example of the LED 12 and diffusion lens 14 in the corner region P 1 of the rectangular region RA.", "As shown in the drawing, the backlight 3 may have a structure obtained by combining the embodiments 2 and 3.", "In other words, the backlight 3 may be structured in such a way that (1) the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 is disposed such that the central axis C thereof is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portion 12 a of the LED 12 and (2) the diffusion lens 14 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA.", "In this structure, in the brightness distribution of the light that is emitted from the LED 12 in each corner region P 1 and obtained via the diffusion lens 14 , even in a case where the deviation amount of the diffusion lens 14 from the light emitting portion 12 a is small, it is possible to raise the brightness on the outer peripheral side of the rectangular region RA with respect to the axis (e.g., central axis D of the LED 12 ) that passes through the light emitting portion 12 a and is perpendicular to the mounting surface 11 a 1 .", "In this way, even in the case where the deviation amount of the diffusion lens 14 from the light emitting portion 12 a is small, it is possible to surely obtain the effect of alleviating the brightness declining at the four corners of the illumination region.", "Besides, in a case where the deviation amount of the diffusion lens 14 is enlarged, it is possible to further alleviate the brightness declining at the four corners of the illumination region in cooperation with the above inclination of the diffusion lens 14 .", "Besides, FIG. 24 is a cross-sectional view showing still another disposition example of the LED 12 and diffusion lens 14 in the corner region P 1 of the rectangular region RA.", "As shown in the drawing, the backlight 3 may have a structure obtained by combining all the embodiments 1 to 3.", "In other words, the backlight 3 may be structured in such a way that (1) the LED 12 in each corner region P 1 is disposed such that the central axis D thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA, (2) the diffusion lens 14 corresponding to the LED 12 in each corner region P 1 is disposed such that the central axis C thereof is located at a position closer to the outer peripheral side of the rectangular region RA than the light emitting portion 12 a of the LED 12 , further (3) the diffusion lens 14 is disposed such that the central axis C thereof inclines from the direction perpendicular to the mounting surface 11 a 1 (bottom plate 11 a ) toward the outer peripheral side of the rectangular region RA.", "In this structure, in the brightness distribution of the light that is emitted from the LED 12 in each corner region P 1 and obtained via the diffusion lens 14 , even in a case where at least one of the inclination angle of the LED 12 , the deviation amount of the diffusion lens 14 and the inclination angle of the diffusion lens 14 is small, it is possible to raise the brightness on the outer peripheral side of the rectangular region RA and to alleviate the brightness declining at the four corners of the illumination region.", "Besides, it is possible to significantly alleviate the brightness declining at the four corners of the illumination region by means of a synergy effect of the inclination of the LED 12 , the deviation of the diffusion lens 14 and the inclination of the diffusion lens 14 .", "In the meantime, the planar light source device and liquid crystal display device represented in each embodiment are expressible as follows.", "A planar light source device according to one embodiment of the present invention comprises a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, wherein the rectangular region has, at four corners thereof corner regions where at least one of the light sources is disposed, and the light source located at each of the corner regions is disposed such that a central axis thereof inclines from a direction perpendicular to the mounting surface toward an outer peripheral side of the rectangular region.", "According to the above structure, in the brightness distribution of the light emitted from the light source in each corner region, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis inclines with respect to the axis that passes through the light source and is perpendicular to the mounting surface.", "In this way, even in the structure in which to achieve low cost by reduction in the number of light sources mounted, the disposition region for the light sources is made smaller than the size of the bottom plate and the disposition density of the light sources in the disposition region is made lower in the peripheral portion than in the central portion, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the light source in each corner region.", "In the above planar light source device, the light source located in each of the corner regions may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward each apex of the four corners of the rectangular region.", "In this case, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the light source in each corner region and to surely alleviate the brightness declining at the four corners of the illumination region.", "The above planar light source device may include a diffusion lens that is disposed correspondingly to each of the plurality of light sources and diffuses the light emitted from the light source.", "In this case, the light from the light source is diffused by the diffusion lens;", "accordingly, the brightness decline at the four corners becomes more inconspicuous.", "Besides, even in a case where the interval between neighboring light sources is large, dot-like unevenness becomes unlikely to occur in the brightness distribution by each light source;", "accordingly, it is possible to achieve low cost by further reducing the number of light sources mounted.", "In each of the corner regions of the above planar light source device, the diffusion lens may be disposed such that a central axis thereof is located at a position closer to the outer peripheral side of the rectangular region than the light emitting portion of the light source.", "In this structure, in the brightness distribution of the light that is emitted from the light source and obtained via the diffusion lens, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens deviates) of the rectangular region with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface.", "In this way, even in the case where the inclination angle of the central axis of the light source is small, it is possible to surely alleviate the brightness declining at the four corners of the illumination region.", "In each of the corner regions of the above planar light source device, the diffusion lens may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward the outer peripheral side of the rectangular region.", "In this structure, in the brightness distribution of the light that is emitted from the light source and obtained via the diffusion lens, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis of the diffusion lens inclines with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface.", "In this way, even in the case where the inclination angle of the central axis of the light source is small, it is possible to surely alleviate the brightness declining at the four corners of the illumination region.", "In the above planar light source device, when the rectangular region is divided into an outermost peripheral region including each of the corner regions and an inner region with respect to the outermost peripheral region, the light source located in the outermost peripheral region may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward the outer peripheral side of the rectangular region.", "In this case, in the brightness distribution of the light emitted from the light source in the outermost peripheral region in the rectangular region, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis inclines with respect to the axis that passes through the light source and is perpendicular to the mounting surface.", "In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and it is possible to alleviate the frame-shaped brightness unevenness occurring.", "In addition, by illuminating the central portion of the illumination region by means of the light sources located in the region inside the outermost peripheral region, it is possible to obtain the above effects while securing the brightness at the central portion.", "A planar light source device according to another embodiment of the present invention comprises a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, the planar light source device further comprising a diffusion lens that is disposed correspondingly to each of the plurality of light sources and diffuses light emitted from the light source, wherein the rectangular region has, at four corners thereof, corner regions where at least one of the light sources is disposed, and the diffusion lens corresponding to the light source located in each of the corner regions is disposed such that a central axis thereof is located at a position closer to an outer peripheral side of the rectangular region than a light emitting portion of the light source.", "According to the above structure, in the brightness distribution of the light that is emitted from the light source in each corner region and obtained via the diffusion lens, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens deviates) of the rectangular region with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface.", "In this way, even in the structure in which to achieve low cost by reduction in the number of light sources mounted, the disposition region for the light sources is made smaller than the size of the bottom plate and the disposition density of the light sources in the disposition region is made lower in the peripheral portion than in the central portion, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the light source in each corner region.", "Besides, the light from the light source is diffused by the diffusion lens;", "accordingly, the brightness decline at the four corners becomes more inconspicuous.", "Besides, even in the case where the interval between neighboring light sources is large, the dot-like unevenness becomes unlikely to occur in the brightness distribution by each light source;", "accordingly, it is possible to achieve low cost by further reducing the number of light sources mounted.", "In the above planar light source device, the diffusion lens may be disposed such that the central axis thereof is located at a position closer to each apex of the four corners of the rectangular region than the light emitting portion of the light source.", "In this case, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the light source in each corner region and to surely alleviate the brightness declining at the four corners of the illumination region.", "In the above planar light source device, the diffusion lens may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward the outer peripheral side of the rectangular region.", "In this structure, in the brightness distribution of the light that is emitted from the light source and obtained via the diffusion lens, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis of the diffusion lens inclines with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface.", "In this way, even in the case where the deviation amount of the diffusion lens with respect to the light source (light emitting portion) is small, it is possible to alleviate the brightness declining at the four corners of the illumination region.", "In the above planar light source device, when the rectangular region is divided into the outermost peripheral region including each of the corner regions and the inner region with respect to the outermost peripheral region, the diffusion lens corresponding to the light source located in the outermost peripheral region may be disposed such that the central axis thereof is located at a position closer to the outer peripheral side of the rectangular region than the light emitting portion of the light source.", "In this case, in the brightness distribution of the light that is emitted from the light source in the outermost peripheral region in the rectangular region and obtained via the diffusion lens, it is possible to raise the brightness on the outer peripheral side (side toward which the diffusion lens deviates) of the rectangular region with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface.", "In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and it is possible to alleviate the frame-shaped brightness unevenness occurring.", "In addition, by illuminating the central portion of the illumination region by means of the light sources located in the region inside the outermost peripheral region, it is possible to obtain the above effects while securing the brightness at the central portion.", "A planar light source device according to still another embodiment of the present invention comprises a plurality of light sources, and a bottom plate that has a mounting surface on which the plurality of light sources are mounted, wherein the plurality of light sources are two-dimensionally disposed in a rectangular region of the mounting surface that is smaller than a size of the bottom plate, and disposition density of the light sources in the rectangular region is lower in a peripheral portion than in a central portion, the planar light source device further comprising a diffusion lens that is disposed correspondingly to each of the plurality of light sources and diffuses light emitted from the light source, wherein the rectangular region has, at four corners thereof, corner regions where at least one of the light sources is disposed, and the diffusion lens corresponding to the light source located in each of the corner regions is disposed such that a central axis thereof inclines from a direction perpendicular to the mounting surface toward an outer peripheral side of the rectangular region.", "According to the above structure, in the brightness distribution of the light that is emitted from the light source in each corner region and obtained via the diffusion lens, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis of the diffusion lens inclines with respect to the axis that passes through the light source and is perpendicular to the mounting surface.", "In this way, even in the structure in which to achieve low cost by reduction in the number of light sources mounted, the disposition region for the light sources is made smaller than the size of the mounting surface and the disposition density of the light sources in the disposition region is made lower in the peripheral portion than in the central portion, it is possible to alleviate the brightness declining at the four corners of the illumination region by means of the illumination by the light source in each corner region.", "Besides, the light from the light source is diffused by the diffusion lens;", "accordingly, the brightness decline at the four corners of the illumination region becomes more inconspicuous.", "Besides, even in the case where the interval between the neighboring light sources is large, the dot-like unevenness becomes unlikely to occur in the brightness distribution by each light source;", "accordingly, it is possible to achieve low cost by further reducing the number of light sources mounted.", "In the above planar light source device, the diffusion lens may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward each apex of the four corners of the rectangular region.", "In this case, it is possible to surely supply the light to the four corners of the illumination region by means of the illumination by the light source in each corner region and to surely alleviate the brightness declining at the four corners of the illumination region.", "In the above planar light source device, when the rectangular region is divided into the outermost peripheral region including each of the corner regions and the inner region with respect to the outermost peripheral region, the diffusion lens corresponding to the light source located in the outermost peripheral region may be disposed such that the central axis thereof inclines from the direction perpendicular to the mounting surface toward the outer peripheral side of the rectangular region.", "In this case, in the brightness distribution of the light that is emitted from the light source in the outermost peripheral region in the rectangular region and obtained via the diffusion lens, it is possible to raise the brightness on the side (outer peripheral side of the rectangular region) toward which the central axis of the diffusion lens inclines with respect to the axis that passes through the light emitting portion of the light source and is perpendicular to the mounting surface.", "In this way, it is possible to alleviate the brightness declining not only at the four corners of the illumination region but also at the outer peripheral portion, and it is possible to alleviate the frame-shaped brightness unevenness occurring.", "In addition, by illuminating the central portion of the illumination region by means of the light sources located in the region inside the outermost peripheral region, it is possible to obtain the above effects while securing the brightness at the central portion.", "In the above planar light source device, when two directions parallel to the mounting surface and perpendicular to each other are defined as a first direction and a second direction, each of the corner regions may be a region where both-end regions when the rectangular region is divided into three or more regions in the first direction and both-end regions when the rectangular region is divided into three or more regions in the second direction overlie each other.", "In this case, it is possible to surely alleviate the brightness decline at the four corners of the illumination region by means of the light source located in each corner region while securing the illumination brightness in a region other than the four corners of the illumination region by means of the light source located in a region other than the corner region, and possible to alleviate the brightness unevenness of the entire illumination region.", "The above planar light source device may be of direct type that illuminates an illumination target from right under in a planar manner by means of the plurality of light sources.", "In the case of the direct type, the brightness decline easily occurs at the four corners of the illumination region because of the reduction in the number of light sources mounted compared to an edge-light type;", "accordingly, the structure according to each embodiment of the present invention becomes effective.", "In the above planar light source device, the plurality of light sources each may be formed of a light emitting diode.", "In the structure that uses an LED as the light source, the brightness decline easily occurs at the four corners of the illumination region because of the reduction in the number of light sources mounted compared to a structure that uses a tube-like light source (e.g., cold-cathode tube);", "accordingly, the structure according to each embodiment of the present invention becomes effective.", "The above planar light source device may further include a reflection sheet that has an opening portion from which each of the plurality of light sources is exposed, is disposed on the bottom plate, and reflects the light emitted from the light source, wherein the reflection sheet may have an edge portion that rises obliquely from the bottom plate on the outer side of the rectangular region.", "In the structure in which the peripheral portion of the illumination region is illuminated by means of the light that is emitted from the light source and reflected by the edge portion of the reflection sheet, the light source is not disposed in the peripheral portion of the bottom plate to form the edge portion;", "accordingly, it is possible to reduce the number of light sources mounted, but the light has difficulty in reaching the four corners of the illumination region.", "Accordingly, the structure according to each embodiment of the present invention, which is able alleviate the brightness decline at the four corners of the illumination region, becomes very effective in the case of achieving reduction in the number of light sources mounted by means of the illumination that uses the edge portion of the reflection sheet.", "The liquid crystal display device represented in the embodiments of the present invention includes the above planar light source device and a liquid crystal panel that modulates the light supplied from the planar light source device to perform display.", "In this structure, it is possible to alleviate the brightness declining at the four corners of the screen of the liquid crystal panel and improve the display quality.", "INDUSTRIAL APPLICABILITY The planar light source device according to the present invention is usable for a backlight of a liquid crystal display device, for example.", "REFERENCE SIGNS LIST 1 liquid crystal display device 2 liquid crystal panel 3 backlight (planar light source device) 11 a bottom plate 11 a 1 mounting surface 12 LED (light source, light emitting diode) 14 diffusion lens 17 reflection sheet 17 a opening portion 17 b edge portion C central axis D central axis P 1 corner region P 2 outer peripheral region (outermost peripheral region) P 3 central region RA rectangular region Rc central portion Rp peripheral portion" ]
CROSS-REFERENCE [0001] This application is a continuation of U.S. application Ser. No. 09/251,981, filed Feb. 17, 1999, entitled “Transmit Gating in a Wireless Communication System” which claims the benefit of U.S. provisional application No. 60/075,211, filed on Feb. 19, 1998 both are assigned to the assignee of the present invention. The disclosure of this provisional application is incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] I. Field of the Invention [0003] The present invention relates to communications. More particularly, the present invention relates to a novel and improved method and apparatus for transmitting variable rate data in a wireless communication system, and for assisting a hard handoff. [0004] II. Description of the Related Art [0005] The use of code division multiple access (CDMA) modulation techniques is one of several techniques for facilitating communications in which a large number of system users are present. Other multiple access communication system techniques, such as time division multiple access (TDMA) and frequency division multiple access (FDMA) are known in the art. However, the spread spectrum modulation techniques of CDMA have significant advantages over these modulation techniques for multiple access communication systems. The use of CDMA techniques in a multiple access communication system is disclosed in U.S. Pat. No. 4,901,307, entitled “SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS”, assigned to the assignee of the present invention, and incorporated by reference herein. The use of CDMA techniques in a multiple access communication system is further disclosed in U.S. Pat. No. 5,103,459, entitled “SYSTEM AND METHOD FOR GENERATING SIGNAL WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM”, assigned to the assignee of the present invention and incorporated by reference herein. [0006] CDMA by its inherent nature of being a wideband signal offers a form of frequency diversity by spreading the signal energy over a wide bandwidth. Therefore, frequency selective fading affects only a small part of the CDMA signal bandwidth. Space or path diversity is obtained by providing multiple signal paths through simultaneous links from a mobile user through two or more cell-sites. Furthermore, path diversity may be obtained by exploiting the multipath environment through spread spectrum processing by allowing a signal arriving with different propagation delays to be received and processed separately. Examples of path diversity are illustrated in U.S. Pat. No. 5,101,501 entitled “METHOD AND SYSTEM FOR PROVIDING A SOFT HANDOFF IN COMMUNICATIONS IN A CDMA CELLULAR TELEPHONE SYSTEM”, and U.S. Pat. No. 5,109,390 entitled “DIVERSITY RECEIVER IN A CDMA CELLULAR TELEPHONE SYSTEM”, both assigned to the assignee of the present invention and incorporated by reference herein. [0007] A method for transmission of speech in digital communication systems that offers particular advantages in increasing capacity while maintaining high quality of perceived speech is by the use of variable rate speech encoding. The method and apparatus of a particularly useful variable rate speech encoder is described in detail in U.S. Pat. No. 5,414,796, entitled “VARIABLE RATE VOCODER”, assigned to the assignee of the present invention and incorporated by reference herein. [0008] The use of a variable rate speech encoder provides for data frames of maximum speech data capacity when the speech encoder is providing speech data at a maximum rate. When the variable rate speech encoder is providing speech data at a less that maximum rate, there is excess capacity in the transmission frames. A method for transmitting additional data in transmission frames of a fixed predetermined size, wherein the source of the data for the data frames is providing the data at a variable rate, is described in detail in U.S. Pat. No. 5,504,773, entitled “METHOD AND APPARATUS FOR THE FORMATTING OF DATA FOR TRANSMISSION”, assigned to the assignee of the present invention and incorporated by reference herein. In the above mentioned patent application, a method and apparatus is disclosed for combining data of differing types from different sources in a data frame for transmission. [0009] In frames containing less data than a predetermined capacity, power consumption may be lessened by transmission gating a transmission amplifier such that only parts of the frame containing data are transmitted. Furthermore, message collisions in a communication system may be reduced if the data is placed into frames in accordance with a predetermined pseudorandom process. A method and apparatus for gating the transmission and for positioning the data in the frames is disclosed in U.S. Pat. No. 5,659,569, entitled “DATA BURST RANDOMIZER”, assigned to the assignee of the present invention and incorporated by reference herein. [0010] A useful method of power control of a mobile in a communication system is to monitor the power of the received signal from the wireless communication device at a base station. In response to the monitored power level, the base station transmits power control bits to the wireless communication device at regular intervals. A method and apparatus for controlling transmission power in this fashion is disclosed in U.S. Pat. No. 5,056,109, entitled “METHOD AND APPARATUS FOR CONTROLLING TRANSMISSION POWER IN A CDMA CELLULAR MOBILE TELEPHONE SYSTEM”, assigned to the assignee of the present invention and incorporated by reference herein. [0011] In a communication system that provides data using a QPSK modulation format, very useful information can be obtained by taking the cross product of the I and Q components of the OPSK signal. By knowing the relative phases of the two components, one can determine roughly the velocity of the wireless communication device in relation to the base station. A description of a circuit for determining the cross product of the I and Q components in a QPSK modulation communication system is disclosed in U.S. Pat. No. 5,506,865, entitled “PILOT CARRIER DOT PRODUCT CIRCUIT”, assigned to the assignee of the present invention and incorporated by reference herein. [0012] There has been an increasing demand for wireless communications systems to be able to transmit digital information at high rates. One method for sending high rate digital data from a wireless communication device to a central base station is to allow the wireless communication device to send the data using spread spectrum techniques of CDMA. One method that is proposed is to allow the wireless communication device to transmit its information using a small set of orthogonal channels. Such a method is described in detail in co-pending U.S. Pat. No. 6,396,804, entitled “HIGH DATA RATE CDMA WIRELESS COMMUNICATION SYSTEM”, assigned to the assignee of the present invention and incorporated by reference herein. [0013] In the just-mentioned application, a system is disclosed in which a pilot signal is transmitted on the reverse link (the link from the wireless communication device to the base station) to enable coherent demodulation of the reverse link signal at the base station. Using the pilot signal data, coherent processing can be performed at the base station by determining and removing the phase offset of the reverse link signal. Also, the pilot data can be used to optimally weigh multipath signals received with different time delays before being combined in a rake receiver. Once the phase offset is removed, and the multipath signals properly weighted, the multipath signals can be combined to decrease the power at which the reverse link signal must be received for proper processing. This decrease in the required receive power allows greater transmission rates to be processed successfully, or conversely, the interference between a set of reverse link signals to be decreased. [0014] While some additional transmit power is necessary for the transmission of the pilot signal, in the context of higher transmission rates the ratio of pilot signal power to the total reverse link signal power is substantially lower than that associated with lower data rate digital voice data transmission cellular systems. Thus, within a high data rate CDMA system, the E b /N 0 gains achieved by the use of a coherent reverse link outweigh the additional power necessary to transmit pilot data from each wireless communication device. [0015] An additional benefit of the reverse link described in this co-pending application is that it generates less amplitude modulation (AM) interference due to its continuous-transmit nature. Thus, users with sensitive electronic equipment such as hearing aids and pacemakers will experience less interference than with a discontinuous transmit reverse link. Another example of the use of continuous transmission to reduce AM interference is given in co-pending U.S. Pat. No. 6,205,190, filed Apr. 29, 1996, entitled “SYSTEM AND METHOD FOR REDUCING INTERFERENCE GENERATED BY A CDMA COMMUNICATIONS DEVICE”, assigned to the assignee of the present invention and incorporated herein by reference. [0016] However, when the data rate is relatively low, a continuously-transmitted pilot signal on the reverse link contains more energy relative to the data signal. At these low rates, the benefits of coherent demodulation and reduced interference provided by a continuously-transmitted reverse link pilot signal may be outweighed by the decrease in talk time and system capacity in some applications. A method and system is needed to provide flexibility in reverse link transmission format as needed-to optimize these tradeoffs. [0017] Further, a communications device may need to go into hard handoff from a first system to a second system. If discontinuous transmission is possible, the device may search for the second system during the periods of non-transmission, while maintaining contact with the first system during periods of transmission. SUMMARY OF THE INVENTION [0018] The present invention is a novel and improved method and system for communicating a frame of information according to both a continuous transmit format and a discontinuous transmit format. In one aspect of the present invention, a method is disclosed for transmitting frames of information. The method includes transmitting information continuously throughout the frame when in a continuous transmit mode and the frame is of a first data rate of a plurality of data rates; and transmitting the information discontinuously in the frame when in a discontinuous transmit mode and the frame is of the first data rate. Thus, the present invention contemplates transmitting one or more data rates in either a continuous transmit mode or a discontinuous transmit mode. [0019] The method may further include transmitting the information continuously throughout the frame when the frame is of a second data rate of the plurality of data rates. Thus, the present invention contemplates continuous transmission only for certain data rates, and selection between continuous and discontinuous transmission for other data rates. [0020] In one embodiment of the present invention, the first data rate corresponds to a first transmit power and the second data rate corresponds to a second transmit power, and the first transmit power is less than the second transmit power. In this embodiment, the method includes transmitting the frame of the first data rate at the second transmit power when in the discontinuous transmit mode. Thus, frames transmitted in the discontinuous transmit mode may be transmitted at a higher transmit power than in the continuous transmit mode. [0021] In one embodiment of the present invention, the information is transmitted at a fifty-percent duty cycle during the frame when in the discontinuous transmit mode. This may include transmitting the information during a second half of the frame. [0022] Another embodiment of the present invention includes selecting between the continuous transmit mode and the discontinuous transmit mode in response to a transmit power of the wireless communication device. In other words, the present invention may include selecting the discontinuous transmit mode when the transmit power is less than a predetermined threshold. In an alternate embodiment, the present invention includes selecting between the continuous transmit mode and the discontinuous transmit mode according to a user-defined preference. [0023] The present invention also contemplates a wireless communication device for transmitting frames of information. The wireless communication device includes a variable rate data source for generating the frames of information, each of the frames of information having one of a plurality of data rates. It also includes a transmitter for transmitting the information continuously throughout the frame when in a continuous transmit mode and when the frame is of a first data rate of the plurality of data rates, and for transmitting the information discontinuously in the frame when in a discontinuous transmit mode and when the frame is of the first data rate. Thus, the wireless communication device may transmit frames of a given data rate either continuously or discontinuously. A control processor selects between the continuous transmit mode and the discontinuous transmit mode. The wireless communication device may implement the method of the present invention as summarized briefly above. [0024] The present invention also includes a method for receiving a frame of information in a wireless receiver, wherein the information may be continuously present throughout the frame or discontinuously present in the frame. This method includes filtering the frame of information in a sliding window filter to produce a sliding window phase estimate signal, filtering the frame of information in a block window filter to produce a block window phase estimate signal, and selecting between the sliding window phase estimate signal and the block window phase estimate signal in response to whether the information is continuously present in the frame. [0025] In one embodiment of the present invention, the method includes selecting the sliding window phase estimate signal when the information is continuously present in the frame, and selecting the block window phase estimate signal when the information is discontinuously present in the frame. Additionally, the method may include selecting the block window phase estimate signal before and after a phase discontinuity in the frame. [0026] The present invention further contemplates a wireless receiver for receiving a frame of information wherein the information may be continuously present throughout the frame or discontinuously present in the frame. The wireless receiver includes a sliding window phase estimator for filtering the frame of information in a sliding window to produce a sliding window phase estimate signal, a block window phase estimator for filtering the frame of information in a block window to produce a block window phase estimate signal, and a multiplexer for selecting between the sliding window phase estimate signal and the block window phase estimate signal in response to whether the information is continuously present in the frame. The wireless receiver may implement the method briefly described above. [0027] Additionally, the present invention discloses a method, in a wireless communication system, for communicating a frame of information between a wireless communication device and a wireless base station in a continuous transmit mode and a discontinuous transmit mode. The method includes transmitting, from the wireless communication device, the information continuously throughout the frame when in the continuous transmit mode, and transmitting, from the wireless communication device, a first message notifying the wireless base station of an intention to transmit in a discontinuous mode. In response, the base station transmits a second message acknowledging the intention to transmit in the discontinuous mode, and the wireless communication device transmits the information discontinuously in the frame when in the discontinuous transmit mode, and in response to the second message. [0028] In one embodiment, the method further includes demodulating the frame of information according to a continuous transmit format when the information is continuously present throughout the frame, and demodulating, the frame of information according to a discontinuous transmit format when the information is discontinuously present in the frame. [0029] The present invention further contemplates a wireless communication system for communicating a frame of information in a continuous transmit mode and a discontinuous transmit mode. The wireless communication system includes a wireless communication device and a wireless base station that implement the method described briefly above. [0030] In a final aspect of the present invention, a method and apparatus are disclosed for facilitating hard handoff from a first system to a second system. The device searches for the second system during the periods of non-transmission, while maintaining contact with the first system during periods of transmission. [0031] Gating is supported for rate sets 3, 4, 5 and 6. When a frame is gated, only the symbols within the second half of the frame are sent. This means that symbols 6144 through 12287, numbering from 0, are transmitted. During gating, the maximum frame rate is rate 1/2. [0032] Normally, the blocks are transmitted using continuous transmission, with the exception of the rate 1/8 frame which is gated. The continuous transmission reduces the interference in the audio band. The rate 1/8 frame is gated because it improves the reverse link capacity and the mobile station talk time relative to when continuous transmission is used. [0033] However, rate set 3, 4, 5 and 6 may be commanded into a mode where only rate 1/8, rate 1/4, and rate 1/2 frames are transmitted and are transmitted using gated transmission. This mode is used to allow the mobile station time to retune its receiver and search for systems using frequencies and other technologies (e.g. AMPS and GSM). [0034] During gating, the second half of the frame is transmitted for the following reasons. First, the gating needs to be either in the first half or the second half of the frame. If it were not, then the frame would not contain a contiguous 10 milliseconds for searching. Second, the transmitted portion of the frame needs to occur later in the frame in order to allow the mobile station time to estimate the difference between the measured and expected forward signal to noise ratio. Therefore, during gating, the second half of the frame is sent. [0035] In addition, rate set 3, 4, 5 and 6 may be commanded into a mode where all frames are transmitted using continuous transmission. This mode is used by mobile stations that may need to further reduce audio band interference. A mobile station commanded into gated mode for searching will be commanded to periodically gate N frames out of M frames on the forward link and reverse link simultaneously, starting at system time T. The values of N and M depend on the technology being searched and the number of channels being searched. BRIEF DESCRIPTION OF THE DRAWINGS [0036] The features, objects, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein: [0037] [0037]FIG. 1 is a functional block diagram of an exemplary embodiment of the transmission system of the present invention embodied in wireless communication device 50 ; [0038] [0038]FIG. 2 is a functional block diagram of an exemplary embodiment of modulator 26 of FIG. 1; [0039] [0039]FIG. 3 illustrates four graphs of the average energy transmitted by transmitter 28 of FIG. 1 over a single frame for four different data rates; [0040] [0040]FIG. 4 is a functional block diagram of selected portions of a base station 400 in accordance with the present invention; [0041] [0041]FIG. 5 is an expanded functional block diagram of an exemplary single demodulation chain of demodulator 404 of FIG. 4; and [0042] [0042]FIG. 6 is an expanded functional block diagram of an exemplary pilot filter that uses a sliding window estimator in combination with a block window estimator. [0043] [0043]FIG. 7 is a block diagram of apparatus for assisting in hard handoff. [0044] [0044]FIG. 8 is a block diagram of a method for assisting in hard handoff. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0045] [0045]FIG. 1 illustrates a functional block diagram of an exemplary embodiment of the transmission system of the present invention embodied in wireless communication device 50 . It will be understood by one skilled in the art that the methods described herein could be applied to transmission from a central base station (not shown) as well. It will also be understood that various of the functional blocks shown in FIG. 1 may not be present in other embodiments of the present invention. The functional block diagram of FIG. 1 corresponds to an embodiment that is useful for operation according to the TIA/EIA Standard IS-95C, also referred to commercially as cdma2000. Other embodiments of the present invention are useful for other standards including Wideband CDMA standards and dual-mode CDMA/GSM standards. These other embodiments differ somewhat in the formatting of data for transmission, but still include the inventive principles described herein. [0046] In the exemplary embodiment of FIG. 1, the wireless communication device transmits a plurality of distinct channels of information which are distinguished from one another by short orthogonal spreading sequences as described in the aforementioned U.S. Pat. No. 6,396,804. Five separate code channels are transmitted by the wireless communication device: 1) a first supplemental data channel 38 , 2) a time multiplexed channel of pilot and power control symbols 40 , 3) a dedicated control channel 42 , 4) a second supplemental data channel 44 and 5) a fundamental channel 46 . The first supplemental data channel 38 and second supplemental data channel 44 carry digital data which exceeds the capacity of the fundamental channel 46 such as facsimile, multimedia applications, video, electronic mail messages or other forms of digital data. The multiplexed channel of pilot and power control symbols 40 carries pilots symbols to allow for coherent demodulation of the data channels by the central base station and power control bits to control the energy of transmissions to wireless communication device 50 . Control channel 42 carries control information to the central base station such as modes of operation of wireless communication device 50 , capabilities of wireless communication device 50 and other necessary signaling information. Fundamental channel 46 is the primary channel used to carry the primary information signal from the wireless communication device to the central base station. In the case of speech transmissions, the fundamental channel 46 carries the speech data. [0047] Supplemental data channels 38 and 44 are encoded and processed for transmission by means not shown and provided to modulator 26 . Power control bits are provided to repetition generator 22 which provides repetition of the power control bits before providing the bits to multiplexer (MUX) 24 . In multiplexer 24 the redundant power control bits are time multiplexed with pilot symbols and provided on line 40 to modulator 26 . [0048] Message generator 12 generates necessary control information messages and provides the control message to CRC and tail bit generator 14 . CRC and tail bit generator 14 appends a set of cyclic redundancy check bits which are parity bits used to check the accuracy of the decoding at the central base station and appends a predetermined set of tail bits to the control message. The message is then provided to encoder 16 which provide forward error correction coding upon the control message. The encoded symbols are provided to interleaver 18 which reorders the symbols in accordance with a predetermined interleaver format. The interleaved symbols are provided to repetition generator 20 which repeats the reordered symbols to provide additional time diversity in the transmission. The interleaved symbols are provided on line 42 to modulator 26 . [0049] Variable rate data source 1 generates variable rate data. In the exemplary embodiment, variable rate data source 1 is a variable rate speech encoder such as described in aforementioned U.S. Pat. No. 5,414,796. Variable rate speech encoders are popular in wireless communications because their use increases the battery life of wireless communication devices and increases system capacity. The Telecommunications Industry Association has codified the most popular variable rate speech encoders in such standards as Interim Standard IS-96 and Interim Standard IS-733. These variable rate speech encoders encode the speech signal at four possible rates referred to as full rate, half rate, quarter rate or eighth rate according to the level of voice activity. The rate indicates the number of bits used to encode a frame of speech and varies on a frame by frame basis. Full rate uses a predetermined maximum number of bits to encode the frame, half rate uses half the predetermined maximum number of bits to encode the frame, quarter rate uses one quarter the predetermined maximum number of bits to encode the frame and eighth rate uses one eighth the predetermined maximum number of bits to encode the frame. [0050] Variable rate date source 1 provides the encoded speech frame to CRC and tail bit generator 2 . CRC and tail bit generator 2 appends a set of cyclic redundancy check bits which are parity bits used to check the accuracy of the decoding at the central base station and appends a predetermined set of tail bits to the control message. The frame is then provided to encoder 4 which provide forward error correction coding on the speech frame. The encoded symbols are provided to interleaver 6 which reorders the symbols in accordance with a predetermined interleaver format. The interleaved symbols are provided to repetition generator 8 which provided repetition of the reordered symbols to provide additional time diversity in the transmission. The interleaved symbols are provided on line 46 to modulator 26 . [0051] In the exemplary embodiment, modulator 26 modulates the data channels in accordance with a code division multiple access modulation format and provides the modulated information to transmitter (TMTR) 28 which amplifies and filters the signal and provides the signal through duplexer 30 for transmission through antenna 32 . [0052] [0052]FIG. 2 illustrates a functional block diagram of an exemplary embodiment of modulator 26 of FIG. 1. The first supplemental data channel data is provided on line 38 to spreading element 52 which covers the supplemental channel data in accordance with a predetermined spreading sequence. In the exemplary embodiment, spreading element 52 spreads the supplemental channel data with a short Walsh sequence (+−−+). The spread data is provided to relative gain element 54 which adjusts the gain of the spread supplemental channel data relative to the energy of the pilot and power control symbols. The gain adjusted supplemental channel data is provided to a first summing input of summer 56 . The pilot and power control multiplexed symbols are provided on line 40 to a second summing input of summing element 56 . [0053] Control channel data is provided on line 42 to spreading element 58 which covers the supplemental channel data in accordance with a predetermined spreading sequence. In the exemplary embodiment, spreading element 58 spreads the supplemental channel data with a short Walsh sequence (++++−−−−). The spread data is provided to relative gain element 60 which adjusts the gain of the spread control channel data relative to the energy of the pilot and power control symbols. The gain adjusted control data is provided to a third summing input of summer 56 . [0054] Summing element 56 sums the gain adjusted control data symbols, the gain adjusted supplemental channel symbols and the time multiplexed pilot and power control symbols and provides the sum to a first input of multiplier 72 and a first input of multiplier 78 . [0055] The second supplemental channel is provided on line 44 to spreading element 62 which covers the supplemental channel data in accordance with a predetermined spreading sequence. In the exemplary embodiment, spreading element 62 spreads the supplemental channel data with a short Walsh sequence (+−+−). The spread data is provided to relative gain element 64 which adjusts the gain of the spread supplemental channel data. The gain adjusted supplemental channel data is provided to a first summing input of summer 66 . [0056] The fundamental channel data is provided on line 46 to spreading element 68 which covers the fundamental channel data in accordance with a predetermined spreading sequence. In the exemplary embodiment, spreading element 68 spreads the supplemental channel data with a short Walsh sequence (++−−). The spread data is provided to relative gain element 70 which adjusts the gain of the spread fundamental channel data. The gain adjusted fundamental channel data is provided to a second summing input of summer 66 . [0057] Summing element 66 sums the gain adjusted second supplemental channel data symbols and the fundamental channel data symbols and provides the sum to a first input of multiplier 74 and a first input of multiplier 76 . [0058] In the exemplary embodiment, a pseudonoise spreading using two different short PN sequences (PN I and PN Q ) is used to spread the data. In the exemplary embodiment the short PN sequences, PN I and PN Q , are multiplied by a long PN code to provide additional privacy. The generation of pseudonoise sequences is well known in the art and is described in detail in aforementioned U.S. Pat. No. 5,103,459. A long PN sequence is provided to a first input of multipliers 80 and 82 . The short PN sequence PNI is provided to a second input of multiplier 80 and the short PN sequence PNQ is provided to a second input of multiplier 82 . [0059] The resulting PN sequence from multiplier 80 is provided to respective second inputs of multipliers 72 and 74 . The resulting PN sequence from multiplier 82 is provided to respective second inputs of multipliers 76 and 78 . The product sequence from multiplier 72 is provided to the summing input of subtractor 84 . The product sequence from multiplier 74 is provided to a first summing input of summer 86 . The product sequence from multiplier 76 is provided to the subtracting input of subtractor 84 . The product sequence from multiplier 78 is provided to a second summing input of summer 86 . [0060] The difference sequence from subtractor 84 is provided to baseband filter 88 . Baseband filter 88 performs necessary filtering on the difference sequence and provides the filtered sequence to gain element 92 . Gain element 92 adjusts the gain of the signal and provides the gain to upconverter 96 . Upconverter 96 upconverts the gain adjusted signal in accordance with a QPSK modulation format and provides the unconverted signal to a first input of summer 100 . [0061] The summing sequence from summer 86 is provided to baseband filter 90 . Baseband filter 90 performs necessary filtering on difference sequence and provides the filtered sequence to gain element 94 . Gain element 94 adjusts the gain of the signal and provides the gain to upconverter 98 . Upconverter 98 upconverts the gain adjusted signal in accordance with a QPSK modulation format and provides the upconverted signal to a second input of summer 100 . Summer 100 sums the two QPSK modulated signals and provides the result to transmitter 28 . [0062] [0062]FIG. 3 illustrates four graphs of the average energy transmitted by transmitter 28 over a single frame for full rate 300 , half rate 302 , quarter rate 304 , and eighth rate transmissions 306 and 308 , respectively. As can be seen, for the full rate transmission 300 , the average energy is equal to some predetermined maximum level, E. For half rate transmission 302 , the average energy is equal to half the predetermined maximum level, or E/2. Likewise for quarter-rate transmission 304 , the average energy is equal to one-quarter of the predetermined maximum level, or E/4. [0063] For the eighth-rate transmissions 306 and 308 , there are two possible transmit energies. The first transmission 306 uses continuous transmission at one-eighth of the predetermined maximum level, or E/8. The second transmission 308 (shown in dashed lines), uses a 50% duty cycle transmission at one-quarter of the predetermined maximum level, or E/4. In other words, the present invention provides two separate transmission schemes for the eighth-rate frames: a continuous transmission 306 at E/8, and a discontinuous transmission 308 at E/4. It should be noted that the discontinuous transmission 308 shown in FIG. 3 is merely exemplary. Other duty cycles and energy values are also contemplated by the present invention. For example, a 25% duty cycle at and energy of E/2 may be used in one embodiment. Another embodiment uses a 50% duty cycle with the transmission occurring in the first half of the frame, rather than the second half of the frame as shown in FIG. 3. In yet another embodiment, the transmission start time is randomized during the frame. However, even in the embodiments that do not randomize the transmission, the frame offset staggering in increments of 1.25 ms that is inherent to cdma2000 will distribute the aggregate interference well over a frame duration. [0064] The amount of energy, timing, and duty cycle chosen are not limiting of the present invention. However, in the embodiment shown in FIG. 3, the transmission occurs during the second half of the frame so that power control can be the most accurate at the end of the frame in case the following frame is at a higher data rate. And hence more critical to control accurately since the higher data rate frames are transmitted at higher power and contain more information. Also in the embodiment of FIG. 1, the interleavers 6 and 18 and repetition generators 8 and 20 format the data such that transmitting only the second half of the frame ensures that each of the original information bits are transmitted at least once. [0065] Control processor 36 controls the selection of whether the eighth-rate transmission is continuous or discontinuous. Variable rate data source 1 generates a rate indication to control processor 36 , informing the control processor 36 what the present data rate is. In response, control processor 36 determines whether to gate transmitter 28 on and off to implement the discontinuous transmission of the eighth-rate frames. In one embodiment of the present invention, control processor 36 instructs message generator 12 to generate a message for transmission to the base station over the control channel indicating that the wireless communication device 50 intends to operate in the discontinuous mode. In another embodiment, this message may be a request to operate in discontinuous mode, provided that the base station receiver can support discontinuous mode transmissions. [0066] In one embodiment of the present invention, the control processor 36 may be programmed to always transmit eighth-rate frames according to the discontinuous mode shown as dashed line 308 of FIG. 3. In another embodiment, the control processor 36 may dynamically determine whether to transmit continuously or discontinuously according to the present transmit power of transmitter 28 . Since the AM interference caused by discontinuous transmission is proportional to the amplitude of the transmitted signal, the control processor 36 may compare the present transmit power to a predetermined threshold. If the transmit power is greater than the predetermined threshold, the control processor 36 does not gate the transmitter 28 , resulting in continuous transmission. If the transmit power is less than or equal to the predetermined threshold, the control processor 36 does gate the transmitter 28 , resulting in discontinuous transmission. In such an embodiment, the present transmit power may be determined by any means known in the art. For example, by measuring the output power of transmitter 28 with a conventional signal level detector circuit (not shown), or by accumulating power control commands from the base station, or by monitoring automatic gain control signals being sent to the transmitter 28 . Each of these power measurement techniques is well known in the art and will not be expanded upon herein. [0067] In another embodiment of the present invention, the control processor 36 determines whether to transmit continuously or discontinuously according to user-defined preferences. For example, a menu option may be presented to a user on a graphical display (not shown), allowing the user to enable or disable discontinuous transmission. This embodiment would be particularly useful to persons using sensitive electronic equipment such as hearing aids and pacemakers to allow them to program their wireless communication device to always perform continuous transmission. This allows the user to make their own decision about the tradeoff between battery life and potentially dangerous AM interference. Still another embodiment allows discontinuous transmission during voice calls, and disables discontinuous transmission during data calls. [0068] Typical wireless communication device power amplifiers use significant amounts of current. Also, other transmit signal processing components consume power. An example of the current consumption for various components in the transmitter 28 is shown in TABLE I below. TABLE I Function Current (mA) Power Amplifier Bias Current 110-130 mA Power Amplifier Driver Current  42 mA DAC, filtering, upconverter, AGC  40 mA Total 202 mA [0069] As can be seen from TABLE I above, approximately 202 mA of current may be switched out during discontinuous transmission in a typical wireless communication device. A typical variable rate data source 1 , during normal human speech, will produce eighth-rate frames about 63% of the time. So the potential average current savings for the example of TABLE I is about 63% eighth-rate frames*50% duty cycle*202 mA=64 mA. This is a significant amount of current savings in a typical wireless communication device where the total current consumption is approximately 320 mA at 100% duty cycle. In this example, discontinuous transmission of eighth-rate frames at a 50% duty cycle yields about a 25% increase in talk time. [0070] In addition to the increase in talk time, a system capacity benefit is also realized by the present invention. As is known in the art, the strength of the reverse link pilot signal is driven primarily by the need to track the carrier phase and timing of the reverse link waveform. For most of the time during voice calls a typical wireless communication device is transmitting eighth-rate frames, and therefore is transmitting mostly pilot energy. By turning both the pilot and data signals off during low rate frames, the present invention enhances system capacity. [0071] For example, if we assume that the required traffic component E b /N 0 is 1.6 dB per antenna at 9600 bps, 0.1 dB per antenna at 1500 bps, and the required pilot component E c /N 0 is −22.1 dB per antenna, we find the pilot power fraction shown below in TABLE II. TABLE II Traffic Average Pilot Traffic Data Rate E b /N 0 (dB) E c /N 0 (dB) per (bps) per antenna antenna Pilot Power (%) 9600 1.6 −22 36% Continuous 1500 0.1 −22 86% 50% duty cycle 0.1 −25 76% 1500 [0072] Using the approximations shown above in TABLE II, gating the 1500 bps frames at the 50% duty cycle reduces the average voice call E c /N 0 by 0.85 dB for 8 kbps vocoder operation. [0073] By operating at the exemplary 50% duty cycle for eighth-rate frames, the ability to maintain power control on the reverse link and forward link is affected. The update rate is reduced by a factor of two. For example, the update rate in a cdma2000 system may be reduced from 800 times per second to 400 times per second. This tends to cause an increase in the frame error rate for the eighth-rate frames. However, the increase in capacity and talk time gained by the present invention may outweigh this decrease in power control accuracy in many applications. Additionally, in one embodiment of the present invention, the transmit period (i.e., the time that the transmitter 28 is gated “on”) is arranged to occur at the end of the frame so that power control is most accurate at the frame boundary where the data rate may suddenly increase for the next frame. [0074] Turning now to FIG. 4, a functional block diagram of selected portions of a base station 400 in accordance with the present invention. Reverse link RF signals from the wireless communication device 50 (FIG. 1) are received by receiver (RCVR) 402 , which downconverts the received reverse link RF signals to an baseband frequency. The baseband signal is then demodulated by demodulator 404 . Demodulator 404 is further described with reference to FIG. 5 below. [0075] In the exemplary embodiment of FIG. 4, demodulator 404 has multiple outputs 405 A- 405 N, each corresponding to a different one of the logical channels modulated by modulator 26 of FIG. 1. For example, output 405 A corresponds to the control channel 42 of FIG. 1, and output 405 N corresponds to the fundamental channel 46 of FIG. 1. Demodulator 404 typically will have other demodulated signal outputs. However, for clarity and simplicity, only the control channel 405 A and fundamental channel 405 N are shown in FIG. 4. [0076] The control channel 405 A data is de-interleaved by deinterleaver 406 , decoded by decoder 408 and CRC checked by CRC checker 410 . Each of these functional blocks 406 - 410 performs a complementary function as their counterparts in blocks 14 - 18 of FIG. 1. The control channel data is then passed to control processor 412 for further processing. For example, the control channel data may include a message from the wireless communication device 50 indicating that it either intends, or is requesting, to operate in discontinuous mode. In response to this message, control processor 412 directs message generator 424 (which includes forward link data formatting) to generate a reply message to the wireless communication device 50 , acknowledging reception of the intention or request message. The acknowledgment message is then modulated by modulator 422 and transmitted by transmitter (TMTR) 420 . [0077] The fundamental channel 405 N is de-interleaved by deinterleaver 414 , decoded by decoder 416 and CRC checked by CRC checker 418 . Each of these functional blocks 414 - 418 performs a complementary function as their counterpart blocks 2 - 6 of FIG. 1. The fundamental channel data is then passed to other subsystems (not shown) in the base station 400 for further processing as required. [0078] When control processor 412 receives a request message from wireless communication device 50 to operate in discontinuous mode, it configures deinterleavers 406 , 414 , decoders 408 , 416 , and CRC checkers 410 , 418 for operation in discontinuous mode. In one embodiment, this means that deinterleavers 406 , 414 , decoders 408 , 416 , and CRC checkers 410 , 418 ignore the portions of the frame that do not contain data. [0079] Turning now to FIG. 5, an expanded functional block diagram of an exemplary single demodulation chain of demodulator 404 is shown. In the preferred embodiment, demodulator 404 has one demodulation chain for each information channel. The exemplary demodulator 404 of FIG. 5 performs complex demodulation on signals modulated by the exemplary modulator 26 of FIG. 1. As previously described, receiver (RCVR) 402 downconverts the received reverse link RF signals to a baseband frequency, producing I and Q baseband signals. Despreaders 502 and 504 respectively despread the I and Q baseband signals using the long code from FIG. 1. Baseband filters (BBF) 506 and 508 respectively filter the I and Q baseband signals. [0080] Despreaders 510 and 512 respectively despread the I and Q signals using the PN I sequence of FIG. 2. Similarly, despreaders 514 and 516 respectively despread the Q and I signals using the PN Q sequence of FIG. 2. The outputs of despreaders 510 and 512 are combined in combiner 518 . The output of despreader 516 is subtracted from the output of despreader 512 in combiner 520 . [0081] The respective outputs of combiners 518 and 520 are then Walsh-uncovered in Walsh-uncoverers 522 and 524 with the Walsh code that was used to cover the particular channel of interest in FIG. 2. The respective outputs of the Walsh-uncoverers 522 and 524 are then summed over one Walsh symbol by accumulators 530 and 532 . [0082] The respective outputs of combiners 518 and 520 are also summed over one Walsh symbol by accumulators 526 and 528 . The respective outputs of accumulators 526 and 528 are then applied to pilot filters 534 and 536 . Pilot filters 534 and 536 generate an estimation of the channel conditions by determining the estimated gain and phase of the pilot signal data 40 (see FIG. 1). The output of pilot filter 534 is then complex multiplied by the respective outputs of accumulators 530 and 532 in complex multipliers 538 and 540 . Similarly, the output of pilot filter 536 is complex multiplied by the respective outputs of accumulators 530 and 532 in complex multipliers 542 and 544 . The output of complex multiplier 542 is then summed with the output of complex multiplier 538 in combiner 546 . The output of complex multiplier 544 is subtracted from the output of complex multiplier 540 in combiner 548 . Finally, the outputs of combiners 546 and 548 are combined in combiner 550 to produce the demodulated signal of interest 405 . [0083] Of particular interest to the present invention are pilot filters 534 and 536 . In order to obtain a more accurate estimate of the pilot phase and gain during reception of discontinuous transmissions, the present invention preferably uses a pilot filter that accounts for the 180-degree phase shift at the boundary between continuous and discontinuous transmission in any frame. For example, in the 50% duty cycle transmission 308 (FIG. 3), the pilot filter account for the phase change that occurs at time T/2 in each frame of length T. [0084] One embodiment of the present invention utilizes a “sliding” filter window in combination with a “blocked” filter window in order to avoid improper pilot estimation at the discontinuity boundary. The “blocked” filter is used to estimate the pilot gain and phase immediately before and after any discontinuities in the frame. The “sliding” filter is used to estimate the pilot gain and phase during the remainder of the frame. An exemplary pilot filter that uses a sliding window estimator 600 in combination with a block window estimator 612 is shown in FIG. 6. [0085] In FIG. 6, the output of either accumulator 526 of 528 is applied to shift register 602 , and is also fed forward to combiner 604 . In the exemplary embodiment, shift register 602 is a twelve-stage shift register. The shifted output of shift register 602 is subtracted from the fed-forward input in combiner 604 and provided to combiner 606 . The output of combiner 606 is delayed in delay element 608 and fed back to be combined with the output of combiner 604 in combiner 606 . The output of delay element 608 is also provided to truncator 610 where it is truncated to be 11 bits, and provided as one selectable input to multiplexer 614 . This input to multiplexer 614 represents the sliding window estimate of the pilot phase and gain. [0086] The output of either accumulator 526 or 528 is also provided to block window estimator 612 which simply accumulates the signal over a predetermined period and provides an output representing the block window estimate of the pilot phase and gain as a second selectable input to multiplexer 614 . [0087] Multiplexer 614 is controlled by a select signal from control processor 412 which selects between the sliding window estimate and the block window estimate inputs when operating in the discontinuous transmit mode. During a predetermined period immediately before and after any discontinuity, control processor 412 selects the block window estimate from multiplexer 614 . At other times during the frame, control processor 412 selects the sliding window estimate from multiplexer 614 . The output of multiplexer 614 is then applied to either complex multipliers 538 and 540 or 542 and 544 as shown in FIG. 5. [0088] A slightly different embodiment of the pilot filters 534 , 536 implements a sliding window equal taps FIR filter of 2.5 ms in length. However, due to the phase discontinuity boundaries caused by discontinuous transmission, the, window size is reduced immediately before and after each phase discontinuity boundary to smooth the effect of the phase discontinuity. The filter is updated at the modulation symbol rate which in the exemplary embodiment is one update every two chips. This results in the corresponding phase estimate output also having a two chip resolution. The minimum window size is preferably 1.25 ms, and the window size grows symbol by symbol until it reaches the sliding window buffer size of 2.5 ms. Other embodiments may use combinations of the techniques described above to account for the phase discontinuity boundaries inherent in discontinuous transmission. [0089] [0089]FIG. 7 shows the apparatus of the final aspect of present invention. A Code Division Multiple Access (CDMA)—mobile station 700 includes a symbol source 702 , an interleaver 704 , and a transmitter 706 . The symbol source 702 may be a conventional microphone and vocoder. [0090] The interleaver 704 is connected to receive symbols from the symbol source 702 , and is constructed to interleave them within a frame. The transmitter 706 is connected to receive the frame of interleaved symbols, and is constructed to transmit it. [0091] The apparatus further includes a gate 708 constructed to disable transmission during a fraction F of the frame. The interleaver 704 is constructed to repeat each symbol at least 1/F times. The gate 708 of FIG. 7 is shown as connected directly to the transmitter 706 . It could alternatively fractionally disable transmission by manipulating the interleaver 704 . This alternative structure is more complicated and is not preferred. [0092] Preferably, F=1/2, so the interleaver 704 repeats each symbol at least twice (and preferable more times) in the frame. Thus, even though half of the frame is not transmitted, at least one copy (and preferably more copies) of each symbol is transmitted in each frame. [0093] It is better for the gate 708 to be constructed to disable the transmitter 706 during the first half of the frame rather than the second half. If the transmitted portion of the frame occurs later in the frame, then the mobile station can better estimate the difference between the measured and expected forward signal to noise ratio. [0094] The conventional mobile station 700 includes a frame rate indicator 710 , which produces an indication as to how fast the mobile station 700 is transmitting. This indication is useful for many purposes. In the present invention, it is applied to a selector 712 . The selector 712 is connected to receive the frame rate indication from the frame rate indicator 710 . It is also constructed to selectively enable the gate 708 in response to the frame rate indication. That is, it selectively instructs the gate 708 to turn off the transmitter 706 during the first half of the frame (enables the gate), or instructs the gate 708 to leave the transmitter 706 on for the entire frame (disables the gate). [0095] If desired, the selector 712 may include an adjustment mechanism 714 constructed to enable the gate for all frame rate indications. This is desirable if the mobile station is used in an area where capacity is limited. However, this gating on-and off produces interference in the audio band. When it is important to reduce audio interference, the adjustment mechanism 714 may be constructed to disable the gate for all frame rate indications. Preferably, however, the adjustment mechanism 714 is constructed to enable the gate for a first predetermined set of frame rate indications 716 , and to disable the gate for a second predetermined set of frame rate indications 718 . [0096] The apparatus may also include a mode commander 720 , constructed to command a mode in which transmission of frames is enabled only when one of the first (generally slower) predetermined set of frame rate indications is applied to the mode commander 720 . That is, the transmitter 706 is disabled—for the entire frame, and not just for its first half—for the second (generally faster) set of frame rates. Thus, the transmitter 706 is disabled for the first half of every frame (and also for the second half of some of the frames). This permits a receiver retuner 722 to be connected to receive a mode command from the mode commander 720 . It is constructed to retune a receiver, when so commanded by the mode commander 720 , during the fraction of the frame (the first half) during which transmission is disabled. [0097] The conventional mobile station 700 includes a power indicator 724 , which indicates the power at which the mobile station 700 is transmitting. The present invention uses this by connecting the selector 712 to receive a power indication from the power indicator 724 . The selector 712 is then constructed to selectively enable the gate 708 depending on both the frame rate indication and the power indication. [0098] [0098]FIG. 8 shows the method of operation 800 of the final aspect of the present invention. The present invention may thus be viewed as a method 800 for operating a Code Division Multiple Access (CDMA) mobile station. The conventional method includes providing a sequence of symbols 802 , interleaving each symbol within a frame 804 , and transmitting the frame of interleaved symbols 806 . To this, the present invention adds disabling transmission during a fraction F of the frame 808 . The interleaving 804 thus must include repeating each symbol at least 1/F times. As before, preferably F=1/2, and preferably the fractional disabling of the frame transmission takes place during the first half of the frame. [0099] The fractional disabling of the frame transmission is selective in response to a frame rate indication 810 . The selective fractional disabling 808 may include fractionally disabling the frame transmission at all frame rate indications 812 , or may fractionally disable the frame transmission at no frame rate indication 814 . [0100] The selective fractional disabling 808 may include fractionally disabling the frame transmission for a first predetermined set of frame rate indications, and excludes fractionally disabling the frame transmission for a second predetermined set of frame rate indications. The method may further include commanding a mode 816 in which transmission of frames is enabled only for the first predetermined set of frame rate indications. In this case, it also includes retuning a receiver 818 , when the mode is so commanded, during the fraction of the frame during which transmission is disabled. [0101] The selective fractional disabling may also include fractionally disabling the frame transmission depending on both the frame rate indication 810 and a power indication 820 . [0102] Thus, the present invention provides a method and apparatus for transmit gating in a wireless communication system which allows the wireless communication device to operate either in continuous or discontinuous transmit modes. [0103] The previous description of the preferred embodiments is provided to enable any person skilled in the art to make or use the present invention. The various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
A method and system for communicating a frame of information according to both a continuous transmit format and a discontinuous transmit format. The present invention contemplates transmitting one or more data rates in either a continuous transmit mode ( 814 ) or a discontinuous transmit mode ( 812 ). The present invention contemplates continuous transmission only for certain data rates, and selection between continuous and discontinuous transmission for other data rates ( 810 ). Frames transmitted in the discontinuous transmit mode may be transmitted at a higher transmit power than in the continuous transmit mode ( 820 ). In one embodiment, the information is transmitted at a fifty-percent duty cycle during the second half of the frame when in the discontinuous transmit mode ( 808 ). During periods of non-transmission, an alternative system may be searched for as a possible candidate for hard handoff ( 816 ).
Identify and summarize the most critical technical features from the given patent document.
[ "CROSS-REFERENCE [0001] This application is a continuation of U.S. application Ser.", "No. 09/251,981, filed Feb. 17, 1999, entitled “Transmit Gating in a Wireless Communication System”", "which claims the benefit of U.S. provisional application No. 60/075,211, filed on Feb. 19, 1998 both are assigned to the assignee of the present invention.", "The disclosure of this provisional application is incorporated herein by reference.", "BACKGROUND OF THE INVENTION [0002] I. Field of the Invention [0003] The present invention relates to communications.", "More particularly, the present invention relates to a novel and improved method and apparatus for transmitting variable rate data in a wireless communication system, and for assisting a hard handoff.", "[0004] II.", "Description of the Related Art [0005] The use of code division multiple access (CDMA) modulation techniques is one of several techniques for facilitating communications in which a large number of system users are present.", "Other multiple access communication system techniques, such as time division multiple access (TDMA) and frequency division multiple access (FDMA) are known in the art.", "However, the spread spectrum modulation techniques of CDMA have significant advantages over these modulation techniques for multiple access communication systems.", "The use of CDMA techniques in a multiple access communication system is disclosed in U.S. Pat. No. 4,901,307, entitled “SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS”, assigned to the assignee of the present invention, and incorporated by reference herein.", "The use of CDMA techniques in a multiple access communication system is further disclosed in U.S. Pat. No. 5,103,459, entitled “SYSTEM AND METHOD FOR GENERATING SIGNAL WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM”, assigned to the assignee of the present invention and incorporated by reference herein.", "[0006] CDMA by its inherent nature of being a wideband signal offers a form of frequency diversity by spreading the signal energy over a wide bandwidth.", "Therefore, frequency selective fading affects only a small part of the CDMA signal bandwidth.", "Space or path diversity is obtained by providing multiple signal paths through simultaneous links from a mobile user through two or more cell-sites.", "Furthermore, path diversity may be obtained by exploiting the multipath environment through spread spectrum processing by allowing a signal arriving with different propagation delays to be received and processed separately.", "Examples of path diversity are illustrated in U.S. Pat. No. 5,101,501 entitled “METHOD AND SYSTEM FOR PROVIDING A SOFT HANDOFF IN COMMUNICATIONS IN A CDMA CELLULAR TELEPHONE SYSTEM”, and U.S. Pat. No. 5,109,390 entitled “DIVERSITY RECEIVER IN A CDMA CELLULAR TELEPHONE SYSTEM”, both assigned to the assignee of the present invention and incorporated by reference herein.", "[0007] A method for transmission of speech in digital communication systems that offers particular advantages in increasing capacity while maintaining high quality of perceived speech is by the use of variable rate speech encoding.", "The method and apparatus of a particularly useful variable rate speech encoder is described in detail in U.S. Pat. No. 5,414,796, entitled “VARIABLE RATE VOCODER”, assigned to the assignee of the present invention and incorporated by reference herein.", "[0008] The use of a variable rate speech encoder provides for data frames of maximum speech data capacity when the speech encoder is providing speech data at a maximum rate.", "When the variable rate speech encoder is providing speech data at a less that maximum rate, there is excess capacity in the transmission frames.", "A method for transmitting additional data in transmission frames of a fixed predetermined size, wherein the source of the data for the data frames is providing the data at a variable rate, is described in detail in U.S. Pat. No. 5,504,773, entitled “METHOD AND APPARATUS FOR THE FORMATTING OF DATA FOR TRANSMISSION”, assigned to the assignee of the present invention and incorporated by reference herein.", "In the above mentioned patent application, a method and apparatus is disclosed for combining data of differing types from different sources in a data frame for transmission.", "[0009] In frames containing less data than a predetermined capacity, power consumption may be lessened by transmission gating a transmission amplifier such that only parts of the frame containing data are transmitted.", "Furthermore, message collisions in a communication system may be reduced if the data is placed into frames in accordance with a predetermined pseudorandom process.", "A method and apparatus for gating the transmission and for positioning the data in the frames is disclosed in U.S. Pat. No. 5,659,569, entitled “DATA BURST RANDOMIZER”, assigned to the assignee of the present invention and incorporated by reference herein.", "[0010] A useful method of power control of a mobile in a communication system is to monitor the power of the received signal from the wireless communication device at a base station.", "In response to the monitored power level, the base station transmits power control bits to the wireless communication device at regular intervals.", "A method and apparatus for controlling transmission power in this fashion is disclosed in U.S. Pat. No. 5,056,109, entitled “METHOD AND APPARATUS FOR CONTROLLING TRANSMISSION POWER IN A CDMA CELLULAR MOBILE TELEPHONE SYSTEM”, assigned to the assignee of the present invention and incorporated by reference herein.", "[0011] In a communication system that provides data using a QPSK modulation format, very useful information can be obtained by taking the cross product of the I and Q components of the OPSK signal.", "By knowing the relative phases of the two components, one can determine roughly the velocity of the wireless communication device in relation to the base station.", "A description of a circuit for determining the cross product of the I and Q components in a QPSK modulation communication system is disclosed in U.S. Pat. No. 5,506,865, entitled “PILOT CARRIER DOT PRODUCT CIRCUIT”, assigned to the assignee of the present invention and incorporated by reference herein.", "[0012] There has been an increasing demand for wireless communications systems to be able to transmit digital information at high rates.", "One method for sending high rate digital data from a wireless communication device to a central base station is to allow the wireless communication device to send the data using spread spectrum techniques of CDMA.", "One method that is proposed is to allow the wireless communication device to transmit its information using a small set of orthogonal channels.", "Such a method is described in detail in co-pending U.S. Pat. No. 6,396,804, entitled “HIGH DATA RATE CDMA WIRELESS COMMUNICATION SYSTEM”, assigned to the assignee of the present invention and incorporated by reference herein.", "[0013] In the just-mentioned application, a system is disclosed in which a pilot signal is transmitted on the reverse link (the link from the wireless communication device to the base station) to enable coherent demodulation of the reverse link signal at the base station.", "Using the pilot signal data, coherent processing can be performed at the base station by determining and removing the phase offset of the reverse link signal.", "Also, the pilot data can be used to optimally weigh multipath signals received with different time delays before being combined in a rake receiver.", "Once the phase offset is removed, and the multipath signals properly weighted, the multipath signals can be combined to decrease the power at which the reverse link signal must be received for proper processing.", "This decrease in the required receive power allows greater transmission rates to be processed successfully, or conversely, the interference between a set of reverse link signals to be decreased.", "[0014] While some additional transmit power is necessary for the transmission of the pilot signal, in the context of higher transmission rates the ratio of pilot signal power to the total reverse link signal power is substantially lower than that associated with lower data rate digital voice data transmission cellular systems.", "Thus, within a high data rate CDMA system, the E b /N 0 gains achieved by the use of a coherent reverse link outweigh the additional power necessary to transmit pilot data from each wireless communication device.", "[0015] An additional benefit of the reverse link described in this co-pending application is that it generates less amplitude modulation (AM) interference due to its continuous-transmit nature.", "Thus, users with sensitive electronic equipment such as hearing aids and pacemakers will experience less interference than with a discontinuous transmit reverse link.", "Another example of the use of continuous transmission to reduce AM interference is given in co-pending U.S. Pat. No. 6,205,190, filed Apr. 29, 1996, entitled “SYSTEM AND METHOD FOR REDUCING INTERFERENCE GENERATED BY A CDMA COMMUNICATIONS DEVICE”, assigned to the assignee of the present invention and incorporated herein by reference.", "[0016] However, when the data rate is relatively low, a continuously-transmitted pilot signal on the reverse link contains more energy relative to the data signal.", "At these low rates, the benefits of coherent demodulation and reduced interference provided by a continuously-transmitted reverse link pilot signal may be outweighed by the decrease in talk time and system capacity in some applications.", "A method and system is needed to provide flexibility in reverse link transmission format as needed-to optimize these tradeoffs.", "[0017] Further, a communications device may need to go into hard handoff from a first system to a second system.", "If discontinuous transmission is possible, the device may search for the second system during the periods of non-transmission, while maintaining contact with the first system during periods of transmission.", "SUMMARY OF THE INVENTION [0018] The present invention is a novel and improved method and system for communicating a frame of information according to both a continuous transmit format and a discontinuous transmit format.", "In one aspect of the present invention, a method is disclosed for transmitting frames of information.", "The method includes transmitting information continuously throughout the frame when in a continuous transmit mode and the frame is of a first data rate of a plurality of data rates;", "and transmitting the information discontinuously in the frame when in a discontinuous transmit mode and the frame is of the first data rate.", "Thus, the present invention contemplates transmitting one or more data rates in either a continuous transmit mode or a discontinuous transmit mode.", "[0019] The method may further include transmitting the information continuously throughout the frame when the frame is of a second data rate of the plurality of data rates.", "Thus, the present invention contemplates continuous transmission only for certain data rates, and selection between continuous and discontinuous transmission for other data rates.", "[0020] In one embodiment of the present invention, the first data rate corresponds to a first transmit power and the second data rate corresponds to a second transmit power, and the first transmit power is less than the second transmit power.", "In this embodiment, the method includes transmitting the frame of the first data rate at the second transmit power when in the discontinuous transmit mode.", "Thus, frames transmitted in the discontinuous transmit mode may be transmitted at a higher transmit power than in the continuous transmit mode.", "[0021] In one embodiment of the present invention, the information is transmitted at a fifty-percent duty cycle during the frame when in the discontinuous transmit mode.", "This may include transmitting the information during a second half of the frame.", "[0022] Another embodiment of the present invention includes selecting between the continuous transmit mode and the discontinuous transmit mode in response to a transmit power of the wireless communication device.", "In other words, the present invention may include selecting the discontinuous transmit mode when the transmit power is less than a predetermined threshold.", "In an alternate embodiment, the present invention includes selecting between the continuous transmit mode and the discontinuous transmit mode according to a user-defined preference.", "[0023] The present invention also contemplates a wireless communication device for transmitting frames of information.", "The wireless communication device includes a variable rate data source for generating the frames of information, each of the frames of information having one of a plurality of data rates.", "It also includes a transmitter for transmitting the information continuously throughout the frame when in a continuous transmit mode and when the frame is of a first data rate of the plurality of data rates, and for transmitting the information discontinuously in the frame when in a discontinuous transmit mode and when the frame is of the first data rate.", "Thus, the wireless communication device may transmit frames of a given data rate either continuously or discontinuously.", "A control processor selects between the continuous transmit mode and the discontinuous transmit mode.", "The wireless communication device may implement the method of the present invention as summarized briefly above.", "[0024] The present invention also includes a method for receiving a frame of information in a wireless receiver, wherein the information may be continuously present throughout the frame or discontinuously present in the frame.", "This method includes filtering the frame of information in a sliding window filter to produce a sliding window phase estimate signal, filtering the frame of information in a block window filter to produce a block window phase estimate signal, and selecting between the sliding window phase estimate signal and the block window phase estimate signal in response to whether the information is continuously present in the frame.", "[0025] In one embodiment of the present invention, the method includes selecting the sliding window phase estimate signal when the information is continuously present in the frame, and selecting the block window phase estimate signal when the information is discontinuously present in the frame.", "Additionally, the method may include selecting the block window phase estimate signal before and after a phase discontinuity in the frame.", "[0026] The present invention further contemplates a wireless receiver for receiving a frame of information wherein the information may be continuously present throughout the frame or discontinuously present in the frame.", "The wireless receiver includes a sliding window phase estimator for filtering the frame of information in a sliding window to produce a sliding window phase estimate signal, a block window phase estimator for filtering the frame of information in a block window to produce a block window phase estimate signal, and a multiplexer for selecting between the sliding window phase estimate signal and the block window phase estimate signal in response to whether the information is continuously present in the frame.", "The wireless receiver may implement the method briefly described above.", "[0027] Additionally, the present invention discloses a method, in a wireless communication system, for communicating a frame of information between a wireless communication device and a wireless base station in a continuous transmit mode and a discontinuous transmit mode.", "The method includes transmitting, from the wireless communication device, the information continuously throughout the frame when in the continuous transmit mode, and transmitting, from the wireless communication device, a first message notifying the wireless base station of an intention to transmit in a discontinuous mode.", "In response, the base station transmits a second message acknowledging the intention to transmit in the discontinuous mode, and the wireless communication device transmits the information discontinuously in the frame when in the discontinuous transmit mode, and in response to the second message.", "[0028] In one embodiment, the method further includes demodulating the frame of information according to a continuous transmit format when the information is continuously present throughout the frame, and demodulating, the frame of information according to a discontinuous transmit format when the information is discontinuously present in the frame.", "[0029] The present invention further contemplates a wireless communication system for communicating a frame of information in a continuous transmit mode and a discontinuous transmit mode.", "The wireless communication system includes a wireless communication device and a wireless base station that implement the method described briefly above.", "[0030] In a final aspect of the present invention, a method and apparatus are disclosed for facilitating hard handoff from a first system to a second system.", "The device searches for the second system during the periods of non-transmission, while maintaining contact with the first system during periods of transmission.", "[0031] Gating is supported for rate sets 3, 4, 5 and 6.", "When a frame is gated, only the symbols within the second half of the frame are sent.", "This means that symbols 6144 through 12287, numbering from 0, are transmitted.", "During gating, the maximum frame rate is rate 1/2.", "[0032] Normally, the blocks are transmitted using continuous transmission, with the exception of the rate 1/8 frame which is gated.", "The continuous transmission reduces the interference in the audio band.", "The rate 1/8 frame is gated because it improves the reverse link capacity and the mobile station talk time relative to when continuous transmission is used.", "[0033] However, rate set 3, 4, 5 and 6 may be commanded into a mode where only rate 1/8, rate 1/4, and rate 1/2 frames are transmitted and are transmitted using gated transmission.", "This mode is used to allow the mobile station time to retune its receiver and search for systems using frequencies and other technologies (e.g. AMPS and GSM).", "[0034] During gating, the second half of the frame is transmitted for the following reasons.", "First, the gating needs to be either in the first half or the second half of the frame.", "If it were not, then the frame would not contain a contiguous 10 milliseconds for searching.", "Second, the transmitted portion of the frame needs to occur later in the frame in order to allow the mobile station time to estimate the difference between the measured and expected forward signal to noise ratio.", "Therefore, during gating, the second half of the frame is sent.", "[0035] In addition, rate set 3, 4, 5 and 6 may be commanded into a mode where all frames are transmitted using continuous transmission.", "This mode is used by mobile stations that may need to further reduce audio band interference.", "A mobile station commanded into gated mode for searching will be commanded to periodically gate N frames out of M frames on the forward link and reverse link simultaneously, starting at system time T. The values of N and M depend on the technology being searched and the number of channels being searched.", "BRIEF DESCRIPTION OF THE DRAWINGS [0036] The features, objects, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein: [0037] [0037 ]FIG. 1 is a functional block diagram of an exemplary embodiment of the transmission system of the present invention embodied in wireless communication device 50 ;", "[0038] [0038 ]FIG. 2 is a functional block diagram of an exemplary embodiment of modulator 26 of FIG. 1;", "[0039] [0039 ]FIG. 3 illustrates four graphs of the average energy transmitted by transmitter 28 of FIG. 1 over a single frame for four different data rates;", "[0040] [0040 ]FIG. 4 is a functional block diagram of selected portions of a base station 400 in accordance with the present invention;", "[0041] [0041 ]FIG. 5 is an expanded functional block diagram of an exemplary single demodulation chain of demodulator 404 of FIG. 4;", "and [0042] [0042 ]FIG. 6 is an expanded functional block diagram of an exemplary pilot filter that uses a sliding window estimator in combination with a block window estimator.", "[0043] [0043 ]FIG. 7 is a block diagram of apparatus for assisting in hard handoff.", "[0044] [0044 ]FIG. 8 is a block diagram of a method for assisting in hard handoff.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0045] [0045 ]FIG. 1 illustrates a functional block diagram of an exemplary embodiment of the transmission system of the present invention embodied in wireless communication device 50 .", "It will be understood by one skilled in the art that the methods described herein could be applied to transmission from a central base station (not shown) as well.", "It will also be understood that various of the functional blocks shown in FIG. 1 may not be present in other embodiments of the present invention.", "The functional block diagram of FIG. 1 corresponds to an embodiment that is useful for operation according to the TIA/EIA Standard IS-95C, also referred to commercially as cdma2000.", "Other embodiments of the present invention are useful for other standards including Wideband CDMA standards and dual-mode CDMA/GSM standards.", "These other embodiments differ somewhat in the formatting of data for transmission, but still include the inventive principles described herein.", "[0046] In the exemplary embodiment of FIG. 1, the wireless communication device transmits a plurality of distinct channels of information which are distinguished from one another by short orthogonal spreading sequences as described in the aforementioned U.S. Pat. No. 6,396,804.", "Five separate code channels are transmitted by the wireless communication device: 1) a first supplemental data channel 38 , 2) a time multiplexed channel of pilot and power control symbols 40 , 3) a dedicated control channel 42 , 4) a second supplemental data channel 44 and 5) a fundamental channel 46 .", "The first supplemental data channel 38 and second supplemental data channel 44 carry digital data which exceeds the capacity of the fundamental channel 46 such as facsimile, multimedia applications, video, electronic mail messages or other forms of digital data.", "The multiplexed channel of pilot and power control symbols 40 carries pilots symbols to allow for coherent demodulation of the data channels by the central base station and power control bits to control the energy of transmissions to wireless communication device 50 .", "Control channel 42 carries control information to the central base station such as modes of operation of wireless communication device 50 , capabilities of wireless communication device 50 and other necessary signaling information.", "Fundamental channel 46 is the primary channel used to carry the primary information signal from the wireless communication device to the central base station.", "In the case of speech transmissions, the fundamental channel 46 carries the speech data.", "[0047] Supplemental data channels 38 and 44 are encoded and processed for transmission by means not shown and provided to modulator 26 .", "Power control bits are provided to repetition generator 22 which provides repetition of the power control bits before providing the bits to multiplexer (MUX) 24 .", "In multiplexer 24 the redundant power control bits are time multiplexed with pilot symbols and provided on line 40 to modulator 26 .", "[0048] Message generator 12 generates necessary control information messages and provides the control message to CRC and tail bit generator 14 .", "CRC and tail bit generator 14 appends a set of cyclic redundancy check bits which are parity bits used to check the accuracy of the decoding at the central base station and appends a predetermined set of tail bits to the control message.", "The message is then provided to encoder 16 which provide forward error correction coding upon the control message.", "The encoded symbols are provided to interleaver 18 which reorders the symbols in accordance with a predetermined interleaver format.", "The interleaved symbols are provided to repetition generator 20 which repeats the reordered symbols to provide additional time diversity in the transmission.", "The interleaved symbols are provided on line 42 to modulator 26 .", "[0049] Variable rate data source 1 generates variable rate data.", "In the exemplary embodiment, variable rate data source 1 is a variable rate speech encoder such as described in aforementioned U.S. Pat. No. 5,414,796.", "Variable rate speech encoders are popular in wireless communications because their use increases the battery life of wireless communication devices and increases system capacity.", "The Telecommunications Industry Association has codified the most popular variable rate speech encoders in such standards as Interim Standard IS-96 and Interim Standard IS-733.", "These variable rate speech encoders encode the speech signal at four possible rates referred to as full rate, half rate, quarter rate or eighth rate according to the level of voice activity.", "The rate indicates the number of bits used to encode a frame of speech and varies on a frame by frame basis.", "Full rate uses a predetermined maximum number of bits to encode the frame, half rate uses half the predetermined maximum number of bits to encode the frame, quarter rate uses one quarter the predetermined maximum number of bits to encode the frame and eighth rate uses one eighth the predetermined maximum number of bits to encode the frame.", "[0050] Variable rate date source 1 provides the encoded speech frame to CRC and tail bit generator 2 .", "CRC and tail bit generator 2 appends a set of cyclic redundancy check bits which are parity bits used to check the accuracy of the decoding at the central base station and appends a predetermined set of tail bits to the control message.", "The frame is then provided to encoder 4 which provide forward error correction coding on the speech frame.", "The encoded symbols are provided to interleaver 6 which reorders the symbols in accordance with a predetermined interleaver format.", "The interleaved symbols are provided to repetition generator 8 which provided repetition of the reordered symbols to provide additional time diversity in the transmission.", "The interleaved symbols are provided on line 46 to modulator 26 .", "[0051] In the exemplary embodiment, modulator 26 modulates the data channels in accordance with a code division multiple access modulation format and provides the modulated information to transmitter (TMTR) 28 which amplifies and filters the signal and provides the signal through duplexer 30 for transmission through antenna 32 .", "[0052] [0052 ]FIG. 2 illustrates a functional block diagram of an exemplary embodiment of modulator 26 of FIG. 1. The first supplemental data channel data is provided on line 38 to spreading element 52 which covers the supplemental channel data in accordance with a predetermined spreading sequence.", "In the exemplary embodiment, spreading element 52 spreads the supplemental channel data with a short Walsh sequence (+−−+).", "The spread data is provided to relative gain element 54 which adjusts the gain of the spread supplemental channel data relative to the energy of the pilot and power control symbols.", "The gain adjusted supplemental channel data is provided to a first summing input of summer 56 .", "The pilot and power control multiplexed symbols are provided on line 40 to a second summing input of summing element 56 .", "[0053] Control channel data is provided on line 42 to spreading element 58 which covers the supplemental channel data in accordance with a predetermined spreading sequence.", "In the exemplary embodiment, spreading element 58 spreads the supplemental channel data with a short Walsh sequence (++++−−−−).", "The spread data is provided to relative gain element 60 which adjusts the gain of the spread control channel data relative to the energy of the pilot and power control symbols.", "The gain adjusted control data is provided to a third summing input of summer 56 .", "[0054] Summing element 56 sums the gain adjusted control data symbols, the gain adjusted supplemental channel symbols and the time multiplexed pilot and power control symbols and provides the sum to a first input of multiplier 72 and a first input of multiplier 78 .", "[0055] The second supplemental channel is provided on line 44 to spreading element 62 which covers the supplemental channel data in accordance with a predetermined spreading sequence.", "In the exemplary embodiment, spreading element 62 spreads the supplemental channel data with a short Walsh sequence (+−+−).", "The spread data is provided to relative gain element 64 which adjusts the gain of the spread supplemental channel data.", "The gain adjusted supplemental channel data is provided to a first summing input of summer 66 .", "[0056] The fundamental channel data is provided on line 46 to spreading element 68 which covers the fundamental channel data in accordance with a predetermined spreading sequence.", "In the exemplary embodiment, spreading element 68 spreads the supplemental channel data with a short Walsh sequence (++−−).", "The spread data is provided to relative gain element 70 which adjusts the gain of the spread fundamental channel data.", "The gain adjusted fundamental channel data is provided to a second summing input of summer 66 .", "[0057] Summing element 66 sums the gain adjusted second supplemental channel data symbols and the fundamental channel data symbols and provides the sum to a first input of multiplier 74 and a first input of multiplier 76 .", "[0058] In the exemplary embodiment, a pseudonoise spreading using two different short PN sequences (PN I and PN Q ) is used to spread the data.", "In the exemplary embodiment the short PN sequences, PN I and PN Q , are multiplied by a long PN code to provide additional privacy.", "The generation of pseudonoise sequences is well known in the art and is described in detail in aforementioned U.S. Pat. No. 5,103,459.", "A long PN sequence is provided to a first input of multipliers 80 and 82 .", "The short PN sequence PNI is provided to a second input of multiplier 80 and the short PN sequence PNQ is provided to a second input of multiplier 82 .", "[0059] The resulting PN sequence from multiplier 80 is provided to respective second inputs of multipliers 72 and 74 .", "The resulting PN sequence from multiplier 82 is provided to respective second inputs of multipliers 76 and 78 .", "The product sequence from multiplier 72 is provided to the summing input of subtractor 84 .", "The product sequence from multiplier 74 is provided to a first summing input of summer 86 .", "The product sequence from multiplier 76 is provided to the subtracting input of subtractor 84 .", "The product sequence from multiplier 78 is provided to a second summing input of summer 86 .", "[0060] The difference sequence from subtractor 84 is provided to baseband filter 88 .", "Baseband filter 88 performs necessary filtering on the difference sequence and provides the filtered sequence to gain element 92 .", "Gain element 92 adjusts the gain of the signal and provides the gain to upconverter 96 .", "Upconverter 96 upconverts the gain adjusted signal in accordance with a QPSK modulation format and provides the unconverted signal to a first input of summer 100 .", "[0061] The summing sequence from summer 86 is provided to baseband filter 90 .", "Baseband filter 90 performs necessary filtering on difference sequence and provides the filtered sequence to gain element 94 .", "Gain element 94 adjusts the gain of the signal and provides the gain to upconverter 98 .", "Upconverter 98 upconverts the gain adjusted signal in accordance with a QPSK modulation format and provides the upconverted signal to a second input of summer 100 .", "Summer 100 sums the two QPSK modulated signals and provides the result to transmitter 28 .", "[0062] [0062 ]FIG. 3 illustrates four graphs of the average energy transmitted by transmitter 28 over a single frame for full rate 300 , half rate 302 , quarter rate 304 , and eighth rate transmissions 306 and 308 , respectively.", "As can be seen, for the full rate transmission 300 , the average energy is equal to some predetermined maximum level, E. For half rate transmission 302 , the average energy is equal to half the predetermined maximum level, or E/2.", "Likewise for quarter-rate transmission 304 , the average energy is equal to one-quarter of the predetermined maximum level, or E/4.", "[0063] For the eighth-rate transmissions 306 and 308 , there are two possible transmit energies.", "The first transmission 306 uses continuous transmission at one-eighth of the predetermined maximum level, or E/8.", "The second transmission 308 (shown in dashed lines), uses a 50% duty cycle transmission at one-quarter of the predetermined maximum level, or E/4.", "In other words, the present invention provides two separate transmission schemes for the eighth-rate frames: a continuous transmission 306 at E/8, and a discontinuous transmission 308 at E/4.", "It should be noted that the discontinuous transmission 308 shown in FIG. 3 is merely exemplary.", "Other duty cycles and energy values are also contemplated by the present invention.", "For example, a 25% duty cycle at and energy of E/2 may be used in one embodiment.", "Another embodiment uses a 50% duty cycle with the transmission occurring in the first half of the frame, rather than the second half of the frame as shown in FIG. 3. In yet another embodiment, the transmission start time is randomized during the frame.", "However, even in the embodiments that do not randomize the transmission, the frame offset staggering in increments of 1.25 ms that is inherent to cdma2000 will distribute the aggregate interference well over a frame duration.", "[0064] The amount of energy, timing, and duty cycle chosen are not limiting of the present invention.", "However, in the embodiment shown in FIG. 3, the transmission occurs during the second half of the frame so that power control can be the most accurate at the end of the frame in case the following frame is at a higher data rate.", "And hence more critical to control accurately since the higher data rate frames are transmitted at higher power and contain more information.", "Also in the embodiment of FIG. 1, the interleavers 6 and 18 and repetition generators 8 and 20 format the data such that transmitting only the second half of the frame ensures that each of the original information bits are transmitted at least once.", "[0065] Control processor 36 controls the selection of whether the eighth-rate transmission is continuous or discontinuous.", "Variable rate data source 1 generates a rate indication to control processor 36 , informing the control processor 36 what the present data rate is.", "In response, control processor 36 determines whether to gate transmitter 28 on and off to implement the discontinuous transmission of the eighth-rate frames.", "In one embodiment of the present invention, control processor 36 instructs message generator 12 to generate a message for transmission to the base station over the control channel indicating that the wireless communication device 50 intends to operate in the discontinuous mode.", "In another embodiment, this message may be a request to operate in discontinuous mode, provided that the base station receiver can support discontinuous mode transmissions.", "[0066] In one embodiment of the present invention, the control processor 36 may be programmed to always transmit eighth-rate frames according to the discontinuous mode shown as dashed line 308 of FIG. 3. In another embodiment, the control processor 36 may dynamically determine whether to transmit continuously or discontinuously according to the present transmit power of transmitter 28 .", "Since the AM interference caused by discontinuous transmission is proportional to the amplitude of the transmitted signal, the control processor 36 may compare the present transmit power to a predetermined threshold.", "If the transmit power is greater than the predetermined threshold, the control processor 36 does not gate the transmitter 28 , resulting in continuous transmission.", "If the transmit power is less than or equal to the predetermined threshold, the control processor 36 does gate the transmitter 28 , resulting in discontinuous transmission.", "In such an embodiment, the present transmit power may be determined by any means known in the art.", "For example, by measuring the output power of transmitter 28 with a conventional signal level detector circuit (not shown), or by accumulating power control commands from the base station, or by monitoring automatic gain control signals being sent to the transmitter 28 .", "Each of these power measurement techniques is well known in the art and will not be expanded upon herein.", "[0067] In another embodiment of the present invention, the control processor 36 determines whether to transmit continuously or discontinuously according to user-defined preferences.", "For example, a menu option may be presented to a user on a graphical display (not shown), allowing the user to enable or disable discontinuous transmission.", "This embodiment would be particularly useful to persons using sensitive electronic equipment such as hearing aids and pacemakers to allow them to program their wireless communication device to always perform continuous transmission.", "This allows the user to make their own decision about the tradeoff between battery life and potentially dangerous AM interference.", "Still another embodiment allows discontinuous transmission during voice calls, and disables discontinuous transmission during data calls.", "[0068] Typical wireless communication device power amplifiers use significant amounts of current.", "Also, other transmit signal processing components consume power.", "An example of the current consumption for various components in the transmitter 28 is shown in TABLE I below.", "TABLE I Function Current (mA) Power Amplifier Bias Current 110-130 mA Power Amplifier Driver Current 42 mA DAC, filtering, upconverter, AGC 40 mA Total 202 mA [0069] As can be seen from TABLE I above, approximately 202 mA of current may be switched out during discontinuous transmission in a typical wireless communication device.", "A typical variable rate data source 1 , during normal human speech, will produce eighth-rate frames about 63% of the time.", "So the potential average current savings for the example of TABLE I is about 63% eighth-rate frames*50% duty cycle*202 mA=64 mA.", "This is a significant amount of current savings in a typical wireless communication device where the total current consumption is approximately 320 mA at 100% duty cycle.", "In this example, discontinuous transmission of eighth-rate frames at a 50% duty cycle yields about a 25% increase in talk time.", "[0070] In addition to the increase in talk time, a system capacity benefit is also realized by the present invention.", "As is known in the art, the strength of the reverse link pilot signal is driven primarily by the need to track the carrier phase and timing of the reverse link waveform.", "For most of the time during voice calls a typical wireless communication device is transmitting eighth-rate frames, and therefore is transmitting mostly pilot energy.", "By turning both the pilot and data signals off during low rate frames, the present invention enhances system capacity.", "[0071] For example, if we assume that the required traffic component E b /N 0 is 1.6 dB per antenna at 9600 bps, 0.1 dB per antenna at 1500 bps, and the required pilot component E c /N 0 is −22.1 dB per antenna, we find the pilot power fraction shown below in TABLE II.", "TABLE II Traffic Average Pilot Traffic Data Rate E b /N 0 (dB) E c /N 0 (dB) per (bps) per antenna antenna Pilot Power (%) 9600 1.6 −22 36% Continuous 1500 0.1 −22 86% 50% duty cycle 0.1 −25 76% 1500 [0072] Using the approximations shown above in TABLE II, gating the 1500 bps frames at the 50% duty cycle reduces the average voice call E c /N 0 by 0.85 dB for 8 kbps vocoder operation.", "[0073] By operating at the exemplary 50% duty cycle for eighth-rate frames, the ability to maintain power control on the reverse link and forward link is affected.", "The update rate is reduced by a factor of two.", "For example, the update rate in a cdma2000 system may be reduced from 800 times per second to 400 times per second.", "This tends to cause an increase in the frame error rate for the eighth-rate frames.", "However, the increase in capacity and talk time gained by the present invention may outweigh this decrease in power control accuracy in many applications.", "Additionally, in one embodiment of the present invention, the transmit period (i.e., the time that the transmitter 28 is gated “on”) is arranged to occur at the end of the frame so that power control is most accurate at the frame boundary where the data rate may suddenly increase for the next frame.", "[0074] Turning now to FIG. 4, a functional block diagram of selected portions of a base station 400 in accordance with the present invention.", "Reverse link RF signals from the wireless communication device 50 (FIG.", "1) are received by receiver (RCVR) 402 , which downconverts the received reverse link RF signals to an baseband frequency.", "The baseband signal is then demodulated by demodulator 404 .", "Demodulator 404 is further described with reference to FIG. 5 below.", "[0075] In the exemplary embodiment of FIG. 4, demodulator 404 has multiple outputs 405 A- 405 N, each corresponding to a different one of the logical channels modulated by modulator 26 of FIG. 1. For example, output 405 A corresponds to the control channel 42 of FIG. 1, and output 405 N corresponds to the fundamental channel 46 of FIG. 1. Demodulator 404 typically will have other demodulated signal outputs.", "However, for clarity and simplicity, only the control channel 405 A and fundamental channel 405 N are shown in FIG. 4. [0076] The control channel 405 A data is de-interleaved by deinterleaver 406 , decoded by decoder 408 and CRC checked by CRC checker 410 .", "Each of these functional blocks 406 - 410 performs a complementary function as their counterparts in blocks 14 - 18 of FIG. 1. The control channel data is then passed to control processor 412 for further processing.", "For example, the control channel data may include a message from the wireless communication device 50 indicating that it either intends, or is requesting, to operate in discontinuous mode.", "In response to this message, control processor 412 directs message generator 424 (which includes forward link data formatting) to generate a reply message to the wireless communication device 50 , acknowledging reception of the intention or request message.", "The acknowledgment message is then modulated by modulator 422 and transmitted by transmitter (TMTR) 420 .", "[0077] The fundamental channel 405 N is de-interleaved by deinterleaver 414 , decoded by decoder 416 and CRC checked by CRC checker 418 .", "Each of these functional blocks 414 - 418 performs a complementary function as their counterpart blocks 2 - 6 of FIG. 1. The fundamental channel data is then passed to other subsystems (not shown) in the base station 400 for further processing as required.", "[0078] When control processor 412 receives a request message from wireless communication device 50 to operate in discontinuous mode, it configures deinterleavers 406 , 414 , decoders 408 , 416 , and CRC checkers 410 , 418 for operation in discontinuous mode.", "In one embodiment, this means that deinterleavers 406 , 414 , decoders 408 , 416 , and CRC checkers 410 , 418 ignore the portions of the frame that do not contain data.", "[0079] Turning now to FIG. 5, an expanded functional block diagram of an exemplary single demodulation chain of demodulator 404 is shown.", "In the preferred embodiment, demodulator 404 has one demodulation chain for each information channel.", "The exemplary demodulator 404 of FIG. 5 performs complex demodulation on signals modulated by the exemplary modulator 26 of FIG. 1. As previously described, receiver (RCVR) 402 downconverts the received reverse link RF signals to a baseband frequency, producing I and Q baseband signals.", "Despreaders 502 and 504 respectively despread the I and Q baseband signals using the long code from FIG. 1. Baseband filters (BBF) 506 and 508 respectively filter the I and Q baseband signals.", "[0080] Despreaders 510 and 512 respectively despread the I and Q signals using the PN I sequence of FIG. 2. Similarly, despreaders 514 and 516 respectively despread the Q and I signals using the PN Q sequence of FIG. 2. The outputs of despreaders 510 and 512 are combined in combiner 518 .", "The output of despreader 516 is subtracted from the output of despreader 512 in combiner 520 .", "[0081] The respective outputs of combiners 518 and 520 are then Walsh-uncovered in Walsh-uncoverers 522 and 524 with the Walsh code that was used to cover the particular channel of interest in FIG. 2. The respective outputs of the Walsh-uncoverers 522 and 524 are then summed over one Walsh symbol by accumulators 530 and 532 .", "[0082] The respective outputs of combiners 518 and 520 are also summed over one Walsh symbol by accumulators 526 and 528 .", "The respective outputs of accumulators 526 and 528 are then applied to pilot filters 534 and 536 .", "Pilot filters 534 and 536 generate an estimation of the channel conditions by determining the estimated gain and phase of the pilot signal data 40 (see FIG. 1).", "The output of pilot filter 534 is then complex multiplied by the respective outputs of accumulators 530 and 532 in complex multipliers 538 and 540 .", "Similarly, the output of pilot filter 536 is complex multiplied by the respective outputs of accumulators 530 and 532 in complex multipliers 542 and 544 .", "The output of complex multiplier 542 is then summed with the output of complex multiplier 538 in combiner 546 .", "The output of complex multiplier 544 is subtracted from the output of complex multiplier 540 in combiner 548 .", "Finally, the outputs of combiners 546 and 548 are combined in combiner 550 to produce the demodulated signal of interest 405 .", "[0083] Of particular interest to the present invention are pilot filters 534 and 536 .", "In order to obtain a more accurate estimate of the pilot phase and gain during reception of discontinuous transmissions, the present invention preferably uses a pilot filter that accounts for the 180-degree phase shift at the boundary between continuous and discontinuous transmission in any frame.", "For example, in the 50% duty cycle transmission 308 (FIG.", "3), the pilot filter account for the phase change that occurs at time T/2 in each frame of length T. [0084] One embodiment of the present invention utilizes a “sliding”", "filter window in combination with a “blocked”", "filter window in order to avoid improper pilot estimation at the discontinuity boundary.", "The “blocked”", "filter is used to estimate the pilot gain and phase immediately before and after any discontinuities in the frame.", "The “sliding”", "filter is used to estimate the pilot gain and phase during the remainder of the frame.", "An exemplary pilot filter that uses a sliding window estimator 600 in combination with a block window estimator 612 is shown in FIG. 6. [0085] In FIG. 6, the output of either accumulator 526 of 528 is applied to shift register 602 , and is also fed forward to combiner 604 .", "In the exemplary embodiment, shift register 602 is a twelve-stage shift register.", "The shifted output of shift register 602 is subtracted from the fed-forward input in combiner 604 and provided to combiner 606 .", "The output of combiner 606 is delayed in delay element 608 and fed back to be combined with the output of combiner 604 in combiner 606 .", "The output of delay element 608 is also provided to truncator 610 where it is truncated to be 11 bits, and provided as one selectable input to multiplexer 614 .", "This input to multiplexer 614 represents the sliding window estimate of the pilot phase and gain.", "[0086] The output of either accumulator 526 or 528 is also provided to block window estimator 612 which simply accumulates the signal over a predetermined period and provides an output representing the block window estimate of the pilot phase and gain as a second selectable input to multiplexer 614 .", "[0087] Multiplexer 614 is controlled by a select signal from control processor 412 which selects between the sliding window estimate and the block window estimate inputs when operating in the discontinuous transmit mode.", "During a predetermined period immediately before and after any discontinuity, control processor 412 selects the block window estimate from multiplexer 614 .", "At other times during the frame, control processor 412 selects the sliding window estimate from multiplexer 614 .", "The output of multiplexer 614 is then applied to either complex multipliers 538 and 540 or 542 and 544 as shown in FIG. 5. [0088] A slightly different embodiment of the pilot filters 534 , 536 implements a sliding window equal taps FIR filter of 2.5 ms in length.", "However, due to the phase discontinuity boundaries caused by discontinuous transmission, the, window size is reduced immediately before and after each phase discontinuity boundary to smooth the effect of the phase discontinuity.", "The filter is updated at the modulation symbol rate which in the exemplary embodiment is one update every two chips.", "This results in the corresponding phase estimate output also having a two chip resolution.", "The minimum window size is preferably 1.25 ms, and the window size grows symbol by symbol until it reaches the sliding window buffer size of 2.5 ms.", "Other embodiments may use combinations of the techniques described above to account for the phase discontinuity boundaries inherent in discontinuous transmission.", "[0089] [0089 ]FIG. 7 shows the apparatus of the final aspect of present invention.", "A Code Division Multiple Access (CDMA)—mobile station 700 includes a symbol source 702 , an interleaver 704 , and a transmitter 706 .", "The symbol source 702 may be a conventional microphone and vocoder.", "[0090] The interleaver 704 is connected to receive symbols from the symbol source 702 , and is constructed to interleave them within a frame.", "The transmitter 706 is connected to receive the frame of interleaved symbols, and is constructed to transmit it.", "[0091] The apparatus further includes a gate 708 constructed to disable transmission during a fraction F of the frame.", "The interleaver 704 is constructed to repeat each symbol at least 1/F times.", "The gate 708 of FIG. 7 is shown as connected directly to the transmitter 706 .", "It could alternatively fractionally disable transmission by manipulating the interleaver 704 .", "This alternative structure is more complicated and is not preferred.", "[0092] Preferably, F=1/2, so the interleaver 704 repeats each symbol at least twice (and preferable more times) in the frame.", "Thus, even though half of the frame is not transmitted, at least one copy (and preferably more copies) of each symbol is transmitted in each frame.", "[0093] It is better for the gate 708 to be constructed to disable the transmitter 706 during the first half of the frame rather than the second half.", "If the transmitted portion of the frame occurs later in the frame, then the mobile station can better estimate the difference between the measured and expected forward signal to noise ratio.", "[0094] The conventional mobile station 700 includes a frame rate indicator 710 , which produces an indication as to how fast the mobile station 700 is transmitting.", "This indication is useful for many purposes.", "In the present invention, it is applied to a selector 712 .", "The selector 712 is connected to receive the frame rate indication from the frame rate indicator 710 .", "It is also constructed to selectively enable the gate 708 in response to the frame rate indication.", "That is, it selectively instructs the gate 708 to turn off the transmitter 706 during the first half of the frame (enables the gate), or instructs the gate 708 to leave the transmitter 706 on for the entire frame (disables the gate).", "[0095] If desired, the selector 712 may include an adjustment mechanism 714 constructed to enable the gate for all frame rate indications.", "This is desirable if the mobile station is used in an area where capacity is limited.", "However, this gating on-and off produces interference in the audio band.", "When it is important to reduce audio interference, the adjustment mechanism 714 may be constructed to disable the gate for all frame rate indications.", "Preferably, however, the adjustment mechanism 714 is constructed to enable the gate for a first predetermined set of frame rate indications 716 , and to disable the gate for a second predetermined set of frame rate indications 718 .", "[0096] The apparatus may also include a mode commander 720 , constructed to command a mode in which transmission of frames is enabled only when one of the first (generally slower) predetermined set of frame rate indications is applied to the mode commander 720 .", "That is, the transmitter 706 is disabled—for the entire frame, and not just for its first half—for the second (generally faster) set of frame rates.", "Thus, the transmitter 706 is disabled for the first half of every frame (and also for the second half of some of the frames).", "This permits a receiver retuner 722 to be connected to receive a mode command from the mode commander 720 .", "It is constructed to retune a receiver, when so commanded by the mode commander 720 , during the fraction of the frame (the first half) during which transmission is disabled.", "[0097] The conventional mobile station 700 includes a power indicator 724 , which indicates the power at which the mobile station 700 is transmitting.", "The present invention uses this by connecting the selector 712 to receive a power indication from the power indicator 724 .", "The selector 712 is then constructed to selectively enable the gate 708 depending on both the frame rate indication and the power indication.", "[0098] [0098 ]FIG. 8 shows the method of operation 800 of the final aspect of the present invention.", "The present invention may thus be viewed as a method 800 for operating a Code Division Multiple Access (CDMA) mobile station.", "The conventional method includes providing a sequence of symbols 802 , interleaving each symbol within a frame 804 , and transmitting the frame of interleaved symbols 806 .", "To this, the present invention adds disabling transmission during a fraction F of the frame 808 .", "The interleaving 804 thus must include repeating each symbol at least 1/F times.", "As before, preferably F=1/2, and preferably the fractional disabling of the frame transmission takes place during the first half of the frame.", "[0099] The fractional disabling of the frame transmission is selective in response to a frame rate indication 810 .", "The selective fractional disabling 808 may include fractionally disabling the frame transmission at all frame rate indications 812 , or may fractionally disable the frame transmission at no frame rate indication 814 .", "[0100] The selective fractional disabling 808 may include fractionally disabling the frame transmission for a first predetermined set of frame rate indications, and excludes fractionally disabling the frame transmission for a second predetermined set of frame rate indications.", "The method may further include commanding a mode 816 in which transmission of frames is enabled only for the first predetermined set of frame rate indications.", "In this case, it also includes retuning a receiver 818 , when the mode is so commanded, during the fraction of the frame during which transmission is disabled.", "[0101] The selective fractional disabling may also include fractionally disabling the frame transmission depending on both the frame rate indication 810 and a power indication 820 .", "[0102] Thus, the present invention provides a method and apparatus for transmit gating in a wireless communication system which allows the wireless communication device to operate either in continuous or discontinuous transmit modes.", "[0103] The previous description of the preferred embodiments is provided to enable any person skilled in the art to make or use the present invention.", "The various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty.", "Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein." ]
TECHNICAL FIELD OF THE INVENTION [0001] The present invention relates generally to the field of computer systems architecture and, more particularly, to a system for optimizing read/write performance in a PCI-Express system that is interfaced with a PCI system. BACKGROUND OF THE INVENTION [0002] The speed and performance of modem computer systems continue to advance at an astounding rate. New and improved hardware and software technologies are continually being developed to improve the processing capacities of computers. Usually, such technological advances represent some improvement over previous technologies. Often, however, the new technologies are intended to completely replace the older-rendering them obsolete. [0003] This rapid technological advance creates a number of challenges and problems for computer system designers. Interoperability of systems produced by a wide variety of manufacturers is essential to commercial success. Certain standards for device interfaces and operational protocols must be established and utilized for new technologies. Furthermore, a broad base of existing (or “legacy”) computer systems—utilizing the older, disparate technologies—must be supported to allow end users to migrate to the new technologies without completing replacing their systems every few months. Computer system architects are thus constantly challenged with striking a balance between: extracting optimal performance from new technologies, addressing interoperability requirements, and meeting the needs of legacy system support. [0004] Frequently, such concerns and considerations are addressed through the establishment and observance of industry-wide standards. Various manufacturers and other interested parties collectively determine, for a given technology or technological function, certain required physical and performance parameters. Interoperability and legacy support issues are commonly addressed, as are minimum and maximum performance expectations. Having a standard from which to work, computer system architects may then begin the process of optimizing a particular hardware or software function's design and operation. [0005] Industry standards have been widely relied upon in the design and manufacture a number of computer system components and functions. One particular example is computer bus architectures. Generally speaking, computer bus architectures are concerned with the interface and communication between processing, memory, and input/output system components. One commonly used bus interface is PCI. At the time it was developed, PCI was a very advanced, high-performance parallel bus standard. More recently, a newer bus standard has been developed to more fully utilize new communications technologies (e.g., packet-based, point-to-point). This standard has been called PCI-Express. [0006] Although PCI-Express is intended to eventually replace PCI, it must offer legacy support for existing PCI systems and components. Certain PCI protocol communications and operations must be translated into the proper PCI-Express communication or operation, and vice-versa. With a large number of both PCI and PCI-Express system operations communications, the process of translating between the two gives rise to a number of concerns and considerations. [0007] One such consideration is the process of error detection and handling, and its effects on the efficiency of PCI-Express communications. Under current PCI-Express standards, PCI parity bit errors that occur during read or write transactions are passed to PCI-Express using the EP bit in the PCI-Express packet header. This EP bit indicates that data in the packet is invalid, but does not distinguish the specific location of the error within the data payload. Thus, setting the EP bit during a PCI-Express read or write transaction invalidates the entire data payload, requiring the system to retransmit the entire packet. Even if there is only a single parity error, in one doubleword (DW) out of a large PCI data payload, the EP bit invalidates the entire transaction. This results in increased operational latency, and decreases overall system performance. [0008] As a result, there is a need for a system for optimizing PCI-Express communications, particularly read or write transactions, that processes PCI data parity bit errors without invalidating an entire data payload within which the parity bit error occurs-providing stable and efficient error detection and correction, without negatively impacting system performance, in an easy, cost-effective manner. SUMMARY OF THE INVENTION [0009] The present invention provides a versatile system for optimizing PCI-Express communications, particularly read or write transactions, in an easy, cost-effective manner. The present invention provides structures and methods for processing PCI data parity bit errors without invalidating an entire data payload within which the parity bit error occurs. The system of the present invention provides stable and efficient PCI-Express detection and correction of PCI data errors, without negatively impacting system performance. Specifically, the present invention provides structure and methods that, upon detection of a PCI parity bit error, segregate the data payload packet under transmission into several segments. The DW within which the error occurs is identified. Any portion of the data payload preceding the invalid DW is truncated just prior to the invalid DW and transmitted as a valid packet. Any portion of the data payload following the invalid DW is also separated from that DW and transmitted as a valid packet. The invalid DW itself is transmitted, with indication that it contains invalid data. Thus, by the present invention, re-transmission of data payload is limited to only the portion within which an error occurred. The present invention thus optimizes the efficiency of PCI-Express communications during the handling of PCI parity bit errors, overcoming limitations associated with conventional methodologies. [0010] More specifically, the present invention provides a method of conducting communication between a PCI function and a PCI-Express function. The method comprises providing a PCI-Express function, and a PCI function interfaced to the PCI-Express function. A segregation structure is provided within the PCI-Express function. A data transmission from the PCI function to the PCI-Express function is initiated, and the data transmission is routed through the segregation structure. The segregation structure is operated such that corrupted data within the data transmission is identified and separated from uncorrupted data within the data transmission. The corrupted data is transmitted separately from the uncorrupted data. [0011] The present invention also provides a PCI-Express to PCI bridge device comprising a communicative link between the bridge device and a PCI-Express device, as well as a communicative link between the bridge device and a PCI device. A data storage structure is disposed within the bridge device. A segregation structure is also disposed within the bridge device. The segregation structure is adapted to: receive a data transmission from the PCI device, identify and separate corrupted data within the data transmission from uncorrupted data within the data transmission, and store the data transmission in the data storage structure until the data transmission is forwarded to the PCI-Express device. [0012] The present invention further provides a system for optimizing PCI-Express communications between a PCI function and a PCI-Express function. The system comprises a bridge device communicatively intercoupled between the PCI function and the PCI-Express function. A data storage structure is disposed within the bridge device, and adapted to store data that is to be transmitted to the PCI-Express function. The system also comprises a segregation structure disposed within the bridge device. The segregation structure is adapted to: receive a data transmission from the PCI function, store the data transmission in the data storage structure, identify and separate corrupted data within the data transmission from uncorrupted data within the data transmission, and transmit the corrupted data separately from the uncorrupted data. [0013] Other features and advantages of the present invention will be apparent to those of ordinary skill in the art upon reference to the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0014] For a better understanding of the invention, and to show by way of example how the same may be carried into effect, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: [0015] FIG. 1 is an illustration of one embodiment of a PCI-Express system according to the present invention; [0016] FIG. 2 is an illustration depicting one embodiment of a packet structure according to the PCI-Express standard; [0017] FIG. 3 is an illustration of another embodiment of a PCI-Express system according to the present invention; and [0018] FIG. 4 is an illustration of another embodiment of a PCI-Express system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION [0019] While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The invention will now be described in conjunction with read or write transactions within a PCI-Express architecture. The specific embodiments discussed herein, however, are merely illustrative of specific ways to make and use the invention and do not limit the scope of the invention. [0020] The present invention provides structures and methods for processing PCI data parity bit errors without invalidating an entire data payload within which the parity bit error occurs. More specifically, the present invention provides structure and methods that, upon detection of a PCI parity bit error, segregate the data payload packet under transmission into several segments. The smallest identifiable payload segment within which the PCI parity bit error occurs is identified. In PCI-Express (hereinafter abbreviated PCI-X), this smallest segment is a doubleword (DW). Any portion of the data payload preceding the invalid DW is truncated, just prior to the invalid DW. That portion is transmitted as a valid packet. Any portion of the data payload following the invalid DW is also separated from the invalid DW. That portion is also transmitted as a valid packet. The invalid DW itself is transmitted, with indication that it contains invalid data. The present invention thus limits re-transmission of data payload to only the portion (i.e., a singe DW) within which an error occurred. [0021] Certain aspects and embodiments of the present invention are described herein with reference to terms and concepts from the PCI Express Base Specification. That specification is hereby incorporated by reference. [0022] The present invention is now described with reference to FIG. 1 . System 100 of FIG. 1 provides an illustrative example of an interface 102 between a PCI-X environment 104 and a PCI environment 106 . For purposes of explanation and illustration, interface 102 may be considered to be any available physical or functional coupling or connection (e.g., socket, bus) between environments 104 and 106 suitable for performance in accordance with the present invention. System 100 comprises a PCI-based function 108 , disposed “downstream” of a PCI-X-based function 110 (i.e., the PCI-X function 110 is in a host environment, PCI function 108 is in a peripheral environment). Functions 108 and 110 may comprise any physical or operational devices or structures (e.g., hardware, software) that operate in conformance with the present invention. In most applications, function 110 is referred to as a bridge, providing much or most of the PCI to PCI-X translation functionality. [0023] This particular embodiment is particularly illustrative of application of the present invention to transactions that write from PCI environment 106 to PCI-X environment 104 . Another embodiment, illustrative of a transaction reading from a PCI environment to a PCI-X environment, is described hereinafter. In system 100 , function 108 initiates a write transaction intended for device 112 within PCI-X environment 104 . A communicative link 114 is established, through interface 102 , between function 108 and function 110 . Another communicative link 116 is established between function 110 and device 112 , for routing the data traffic received from function 108 . [0024] Referring now to FIG. 2 , a transmission packet 200 according to the PCI-Express standard is depicted. Packet 200 is comprised of several segments, including framing segments 202 and 204 . Framing segment 202 indicates start-of-packet (SOP), and framing segment 204 indicates end-of-packet (EOP). Packet 200 further comprises sequence number segment 206 , header segment 208 , data payload segment 210 , ECRC segment 212 and LCRC segment 214 . Located after the header 208 and data 210 segments, ECRC segment 212 is an end-to-end cyclic redundancy check (ECRC) code error detection segment, while LCRC segment 214 is a link-to-link cyclic redundancy check (LCRC) code error detection segment. [0025] PCI is a burst mode transmission protocol. In general terms, this means that once PCI transmission begins, data words will continue to be transmitted until the PCI limit has been reached. As a result, for a PCI transaction, data payload 210 in packet 200 can be quite large. PCI error detection generally consists of a single parity bit at the end of each 32 -bit word. [0026] For purposes of illustration, assume that system 100 operates according to the conventional PCI Express Base Specification. Function 110 begins receiving a PCI burst-mode write transaction from function 108 via link 114 . Function 110 stores the received data payload, in a first-in, first-out (FIFO) format, for transmission on to device 112 only after the entire data payload has been received. This scheme, however, can lead to a number of problems—especially when a parity bit error (PERR) is signaled within the PCI data payload. [0027] Under the conventional PCI Express Base Specification, once a parity bit error is detected within data payload 210 , a process of error forwarding is initiated. The entire packet 200 is “poisoned” by setting a field (i.e., the EP field) within header 208 to a certain predetermined value (i.e., l b )—indicating to a receiver of the packet that, somewhere in the data payload 210 , there is corrupt data. The PCI Express Base Specification, however, does not define any mechanism for determining which part or parts of the data payload of a poisoned packet are actually corrupt and which, if any, are not corrupt. Thus, system 100 must initiate a retransmission of the entire packet 200 . Especially in cases where data payload 210 contains a large amount of PCI burst-mode data, this all-or-nothing approach increases system latency and degrades system efficiency and performance significantly. [0028] In contrast, according to the present invention, the entire packet 200 is not poisoned in the event of a parity bit error. According to the present invention, the system does determine which part or parts of the data payload of a poisoned packet are actually corrupt and which, if any, are not corrupt. According to the present invention, any portion of the data payload preceding a corrupt word is truncated immediately prior to the corrupt word and is then transmitted as a separate and complete error-free packet. The present invention determines what, if any, portion of the data payload, following the corrupt word, is error-free and transmits that portion as a separate and complete error-free packet also. The corrupt portion of the data payload is processed in standard error forwarding format-forming and transmitting a separate poisoned packet. Thus, according to the present invention, only the corrupt portion or portions of a PCI transaction need to be retransmitted. In cases where the data payload contains large amounts of PCI burst-mode data, system latencies and efficiency are optimized. [0029] The present invention is now described in greater detail with reference to FIG. 3 . FIG. 3 depicts a system 300 , according to the present invention, comprising the same constituent elements as system 100 . In reference to system 300 , however, function 110 is described in greater detail. Function 110 comprises a segregation structure 302 . Transaction data is routed through structure 302 . Structure 302 receives the write transaction data from link 114 , processes the transaction data, and loads it into a FIFO storage structure 304 —for eventual transmission, through the various protocol layers 306 of function 110 , onto target device 112 . As structure 302 processes data payload 210 , it evaluates the parity error status for each word of the payload, utilizing a suitable parity calculation function (not shown). Upon determining that a parity bit error has occurred for a specific data word, structure 300 halts processing of that data word. Structure 302 initiates transmission of the data already loaded into storage structure 304 as a complete packet—generating the necessary CRC and framing segments to complete that packet. This non-corrupt packet is transmitted on through the protocol layers 306 of function 110 to target device 112 . Structure 302 generates the necessary CRC and framing segments to form a complete packet from the corrupt data. This includes setting the EP field in header 208 to the required error transmission value. Structure 302 initiates transmission of the corrupt data packet to target device 112 , and retransmission of that data is then initiated. To the extent that any non-corrupt data follows the corrupt data, structure 302 initiates transmission of that non-corrupt data as a complete packet—generating the necessary CRC and framing segments. This non-corrupt packet is transmitted on through the protocol layers 306 of function 110 to target device 112 . [0030] Since PCI-X environment 104 provides for transaction reordering, the order in which structure 302 performs transmission of corrupt and non-corrupt packets may be varied, depending upon the specific requirements of a given system. In some embodiments, it may be advantageous for structure 302 to isolate the corrupt data, transmit it as a poisoned packet, and initiate retransmission of that data prior to processing the non-corrupt data that precedes and follows the corrupt data. In other embodiments, it may be advantageous for structure 302 to transmit the non-corrupt data packets first, before processing the corrupt data packet. These and other combinations and variations are comprehended by the present invention. [0031] The functions and structures described herein may be implemented in a number of ways—utilizing or combining a variety of hardware and software constructs. For example, structure 302 may be implemented in circuitry as a portion of a semiconductor device, or as a routine or algorithm operating on a processor. In some embodiments, structure 302 comprises its own separate parity calculation function. In other embodiments, structure 302 is communicatively linked with and utilizes a parity calculation function residing in some separate structure. In certain embodiments, structure 302 is implemented within a PCI slave portion of a bridge device. These and other similar combinations and variations are comprehended by the present invention. [0032] In another illustrative embodiment, the present invention is applied to transactions reading from a PCI environment to a PCI-X environment. Similar in many ways to system 100 , this embodiment is now described with reference to FIG. 4 . System 400 of FIG. 4 comprises an interface 402 between a PCI environment 404 and a PCI-X environment 406 . System 400 comprises a PCI-X-based function 408 , disposed “downstream” of a PCI-based function 410 (i.e., the PCI function 410 is in a host environment, PCI-X function 408 is in a peripheral environment). Functions 408 and 410 may comprise any physical or operational devices or structures (e.g., hardware, software) that operate in conformance with the present invention. In system 400 , function 408 serves as a bridge, providing much or most of the PCI to PCI-X translation functionality. [0033] In system 400 , some device 412 within the PCI-X environment 406 initiates a read transaction intended for function 410 . For example, function 410 may comprise system memory within an older, PCI computer to which a newer PCI-X peripheral 412 is attached. Device 412 is communicatively coupled to function 408 via link 414 . A communicative link 416 is established, through interface 402 , between function 408 and function 410 . Function 408 communicates the read request to function 410 , and begins receiving the data fetched from function 410 . [0034] Function 408 comprises a segregation structure 418 . Again, transaction data is routed through structure 418 . Structure 418 receives read transaction data from link 416 , processes the transaction data, and loads it into a FIFO storage structure 420 —for eventual transmission through the various protocol layers of function 408 to device 412 . As structure 418 processes the data payload, it evaluates the parity error status for each word of the payload, utilizing a suitable parity calculation function (not shown). Upon determining that a parity bit error has occurred for a specific data word, structure 418 halts processing of that data word. Structure 418 initiates transmission of the data already loaded into storage structure 420 as a complete packet—generating the necessary CRC and framing segments to complete that packet. Structure 418 sets the data completion field within the header to indicate to device 412 that this is a complete packet. This non-corrupt packet is transmitted on through the protocol layers to target device 412 . Structure 418 generates the necessary CRC and framing segments to form a complete packet from the corrupt data. This includes setting the EP field in header to the required error transmission value. Structure 418 initiates transmission of the corrupt data packet to target device 412 , and retransmission of that data is then initiated. To the extent that any non-corrupt data follows the corrupt data, structure 418 initiates transmission of that non-corrupt data as a complete packet. [0035] Again, since PCI-X environment 406 provides for reordering of data packets, the order in which structure 418 performs transmission of corrupt and non-corrupt packets may be varied, depending upon the specific requirements of a given system. In some embodiments, it may be advantageous for structure 418 to isolate the corrupt data, transmit it as a poisoned packet, and initiate retransmission of that data prior to processing the non-corrupt data that precedes and follows the corrupt data. In other embodiments, it may be advantageous for structure 418 to transmit the non-corrupt data packets first, before processing the corrupt data packet. These and other combinations and variations are comprehended by the present invention. [0036] The functions and structures described herein may be implemented in a number of ways—utilizing or combining a variety of hardware and software constructs. For example, structure 418 may be implemented in circuitry as a portion of a semiconductor device, or as a routine or algorithm operating on a processor. In some embodiments, structure 418 comprises its own separate parity calculation function. In other embodiments, structure 418 is communicatively linked with and utilizes a parity calculation function residing in some separate structure. [0037] The embodiments and examples set forth herein are presented to best explain the present invention and its practical application and to thereby enable those skilled in the art to make and utilize the invention. However, those skilled in the art will recognize that the foregoing description and examples have been presented for the purpose of illustration and example only. The description as set forth is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching without departing from the spirit and scope of the following claims.
The present invention provides a system for conducting communications in a PCI-Express system ( 300 ). The PCI-Express system is interfaced with a system utilizing another protocol—particularly PCI. The present invention provides a segregation structure ( 302 ) within the PCI-Express system. A data transaction, from the PCI system to the PCI-Express system, is initiated. Data transmission is routed through the segregation structure, which operates such that corrupted data within the data transmission is identified and separated from uncorrupted data within the data transmission. The present invention transmits the corrupted data separately from the uncorrupted data.
Summarize the key points of the given patent document.
[ "TECHNICAL FIELD OF THE INVENTION [0001] The present invention relates generally to the field of computer systems architecture and, more particularly, to a system for optimizing read/write performance in a PCI-Express system that is interfaced with a PCI system.", "BACKGROUND OF THE INVENTION [0002] The speed and performance of modem computer systems continue to advance at an astounding rate.", "New and improved hardware and software technologies are continually being developed to improve the processing capacities of computers.", "Usually, such technological advances represent some improvement over previous technologies.", "Often, however, the new technologies are intended to completely replace the older-rendering them obsolete.", "[0003] This rapid technological advance creates a number of challenges and problems for computer system designers.", "Interoperability of systems produced by a wide variety of manufacturers is essential to commercial success.", "Certain standards for device interfaces and operational protocols must be established and utilized for new technologies.", "Furthermore, a broad base of existing (or “legacy”) computer systems—utilizing the older, disparate technologies—must be supported to allow end users to migrate to the new technologies without completing replacing their systems every few months.", "Computer system architects are thus constantly challenged with striking a balance between: extracting optimal performance from new technologies, addressing interoperability requirements, and meeting the needs of legacy system support.", "[0004] Frequently, such concerns and considerations are addressed through the establishment and observance of industry-wide standards.", "Various manufacturers and other interested parties collectively determine, for a given technology or technological function, certain required physical and performance parameters.", "Interoperability and legacy support issues are commonly addressed, as are minimum and maximum performance expectations.", "Having a standard from which to work, computer system architects may then begin the process of optimizing a particular hardware or software function's design and operation.", "[0005] Industry standards have been widely relied upon in the design and manufacture a number of computer system components and functions.", "One particular example is computer bus architectures.", "Generally speaking, computer bus architectures are concerned with the interface and communication between processing, memory, and input/output system components.", "One commonly used bus interface is PCI.", "At the time it was developed, PCI was a very advanced, high-performance parallel bus standard.", "More recently, a newer bus standard has been developed to more fully utilize new communications technologies (e.g., packet-based, point-to-point).", "This standard has been called PCI-Express.", "[0006] Although PCI-Express is intended to eventually replace PCI, it must offer legacy support for existing PCI systems and components.", "Certain PCI protocol communications and operations must be translated into the proper PCI-Express communication or operation, and vice-versa.", "With a large number of both PCI and PCI-Express system operations communications, the process of translating between the two gives rise to a number of concerns and considerations.", "[0007] One such consideration is the process of error detection and handling, and its effects on the efficiency of PCI-Express communications.", "Under current PCI-Express standards, PCI parity bit errors that occur during read or write transactions are passed to PCI-Express using the EP bit in the PCI-Express packet header.", "This EP bit indicates that data in the packet is invalid, but does not distinguish the specific location of the error within the data payload.", "Thus, setting the EP bit during a PCI-Express read or write transaction invalidates the entire data payload, requiring the system to retransmit the entire packet.", "Even if there is only a single parity error, in one doubleword (DW) out of a large PCI data payload, the EP bit invalidates the entire transaction.", "This results in increased operational latency, and decreases overall system performance.", "[0008] As a result, there is a need for a system for optimizing PCI-Express communications, particularly read or write transactions, that processes PCI data parity bit errors without invalidating an entire data payload within which the parity bit error occurs-providing stable and efficient error detection and correction, without negatively impacting system performance, in an easy, cost-effective manner.", "SUMMARY OF THE INVENTION [0009] The present invention provides a versatile system for optimizing PCI-Express communications, particularly read or write transactions, in an easy, cost-effective manner.", "The present invention provides structures and methods for processing PCI data parity bit errors without invalidating an entire data payload within which the parity bit error occurs.", "The system of the present invention provides stable and efficient PCI-Express detection and correction of PCI data errors, without negatively impacting system performance.", "Specifically, the present invention provides structure and methods that, upon detection of a PCI parity bit error, segregate the data payload packet under transmission into several segments.", "The DW within which the error occurs is identified.", "Any portion of the data payload preceding the invalid DW is truncated just prior to the invalid DW and transmitted as a valid packet.", "Any portion of the data payload following the invalid DW is also separated from that DW and transmitted as a valid packet.", "The invalid DW itself is transmitted, with indication that it contains invalid data.", "Thus, by the present invention, re-transmission of data payload is limited to only the portion within which an error occurred.", "The present invention thus optimizes the efficiency of PCI-Express communications during the handling of PCI parity bit errors, overcoming limitations associated with conventional methodologies.", "[0010] More specifically, the present invention provides a method of conducting communication between a PCI function and a PCI-Express function.", "The method comprises providing a PCI-Express function, and a PCI function interfaced to the PCI-Express function.", "A segregation structure is provided within the PCI-Express function.", "A data transmission from the PCI function to the PCI-Express function is initiated, and the data transmission is routed through the segregation structure.", "The segregation structure is operated such that corrupted data within the data transmission is identified and separated from uncorrupted data within the data transmission.", "The corrupted data is transmitted separately from the uncorrupted data.", "[0011] The present invention also provides a PCI-Express to PCI bridge device comprising a communicative link between the bridge device and a PCI-Express device, as well as a communicative link between the bridge device and a PCI device.", "A data storage structure is disposed within the bridge device.", "A segregation structure is also disposed within the bridge device.", "The segregation structure is adapted to: receive a data transmission from the PCI device, identify and separate corrupted data within the data transmission from uncorrupted data within the data transmission, and store the data transmission in the data storage structure until the data transmission is forwarded to the PCI-Express device.", "[0012] The present invention further provides a system for optimizing PCI-Express communications between a PCI function and a PCI-Express function.", "The system comprises a bridge device communicatively intercoupled between the PCI function and the PCI-Express function.", "A data storage structure is disposed within the bridge device, and adapted to store data that is to be transmitted to the PCI-Express function.", "The system also comprises a segregation structure disposed within the bridge device.", "The segregation structure is adapted to: receive a data transmission from the PCI function, store the data transmission in the data storage structure, identify and separate corrupted data within the data transmission from uncorrupted data within the data transmission, and transmit the corrupted data separately from the uncorrupted data.", "[0013] Other features and advantages of the present invention will be apparent to those of ordinary skill in the art upon reference to the following detailed description taken in conjunction with the accompanying drawings.", "BRIEF DESCRIPTION OF THE DRAWINGS [0014] For a better understanding of the invention, and to show by way of example how the same may be carried into effect, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: [0015] FIG. 1 is an illustration of one embodiment of a PCI-Express system according to the present invention;", "[0016] FIG. 2 is an illustration depicting one embodiment of a packet structure according to the PCI-Express standard;", "[0017] FIG. 3 is an illustration of another embodiment of a PCI-Express system according to the present invention;", "and [0018] FIG. 4 is an illustration of another embodiment of a PCI-Express system according to the present invention.", "DETAILED DESCRIPTION OF THE INVENTION [0019] While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts.", "The invention will now be described in conjunction with read or write transactions within a PCI-Express architecture.", "The specific embodiments discussed herein, however, are merely illustrative of specific ways to make and use the invention and do not limit the scope of the invention.", "[0020] The present invention provides structures and methods for processing PCI data parity bit errors without invalidating an entire data payload within which the parity bit error occurs.", "More specifically, the present invention provides structure and methods that, upon detection of a PCI parity bit error, segregate the data payload packet under transmission into several segments.", "The smallest identifiable payload segment within which the PCI parity bit error occurs is identified.", "In PCI-Express (hereinafter abbreviated PCI-X), this smallest segment is a doubleword (DW).", "Any portion of the data payload preceding the invalid DW is truncated, just prior to the invalid DW.", "That portion is transmitted as a valid packet.", "Any portion of the data payload following the invalid DW is also separated from the invalid DW.", "That portion is also transmitted as a valid packet.", "The invalid DW itself is transmitted, with indication that it contains invalid data.", "The present invention thus limits re-transmission of data payload to only the portion (i.e., a singe DW) within which an error occurred.", "[0021] Certain aspects and embodiments of the present invention are described herein with reference to terms and concepts from the PCI Express Base Specification.", "That specification is hereby incorporated by reference.", "[0022] The present invention is now described with reference to FIG. 1 .", "System 100 of FIG. 1 provides an illustrative example of an interface 102 between a PCI-X environment 104 and a PCI environment 106 .", "For purposes of explanation and illustration, interface 102 may be considered to be any available physical or functional coupling or connection (e.g., socket, bus) between environments 104 and 106 suitable for performance in accordance with the present invention.", "System 100 comprises a PCI-based function 108 , disposed “downstream”", "of a PCI-X-based function 110 (i.e., the PCI-X function 110 is in a host environment, PCI function 108 is in a peripheral environment).", "Functions 108 and 110 may comprise any physical or operational devices or structures (e.g., hardware, software) that operate in conformance with the present invention.", "In most applications, function 110 is referred to as a bridge, providing much or most of the PCI to PCI-X translation functionality.", "[0023] This particular embodiment is particularly illustrative of application of the present invention to transactions that write from PCI environment 106 to PCI-X environment 104 .", "Another embodiment, illustrative of a transaction reading from a PCI environment to a PCI-X environment, is described hereinafter.", "In system 100 , function 108 initiates a write transaction intended for device 112 within PCI-X environment 104 .", "A communicative link 114 is established, through interface 102 , between function 108 and function 110 .", "Another communicative link 116 is established between function 110 and device 112 , for routing the data traffic received from function 108 .", "[0024] Referring now to FIG. 2 , a transmission packet 200 according to the PCI-Express standard is depicted.", "Packet 200 is comprised of several segments, including framing segments 202 and 204 .", "Framing segment 202 indicates start-of-packet (SOP), and framing segment 204 indicates end-of-packet (EOP).", "Packet 200 further comprises sequence number segment 206 , header segment 208 , data payload segment 210 , ECRC segment 212 and LCRC segment 214 .", "Located after the header 208 and data 210 segments, ECRC segment 212 is an end-to-end cyclic redundancy check (ECRC) code error detection segment, while LCRC segment 214 is a link-to-link cyclic redundancy check (LCRC) code error detection segment.", "[0025] PCI is a burst mode transmission protocol.", "In general terms, this means that once PCI transmission begins, data words will continue to be transmitted until the PCI limit has been reached.", "As a result, for a PCI transaction, data payload 210 in packet 200 can be quite large.", "PCI error detection generally consists of a single parity bit at the end of each 32 -bit word.", "[0026] For purposes of illustration, assume that system 100 operates according to the conventional PCI Express Base Specification.", "Function 110 begins receiving a PCI burst-mode write transaction from function 108 via link 114 .", "Function 110 stores the received data payload, in a first-in, first-out (FIFO) format, for transmission on to device 112 only after the entire data payload has been received.", "This scheme, however, can lead to a number of problems—especially when a parity bit error (PERR) is signaled within the PCI data payload.", "[0027] Under the conventional PCI Express Base Specification, once a parity bit error is detected within data payload 210 , a process of error forwarding is initiated.", "The entire packet 200 is “poisoned”", "by setting a field (i.e., the EP field) within header 208 to a certain predetermined value (i.e., l b )—indicating to a receiver of the packet that, somewhere in the data payload 210 , there is corrupt data.", "The PCI Express Base Specification, however, does not define any mechanism for determining which part or parts of the data payload of a poisoned packet are actually corrupt and which, if any, are not corrupt.", "Thus, system 100 must initiate a retransmission of the entire packet 200 .", "Especially in cases where data payload 210 contains a large amount of PCI burst-mode data, this all-or-nothing approach increases system latency and degrades system efficiency and performance significantly.", "[0028] In contrast, according to the present invention, the entire packet 200 is not poisoned in the event of a parity bit error.", "According to the present invention, the system does determine which part or parts of the data payload of a poisoned packet are actually corrupt and which, if any, are not corrupt.", "According to the present invention, any portion of the data payload preceding a corrupt word is truncated immediately prior to the corrupt word and is then transmitted as a separate and complete error-free packet.", "The present invention determines what, if any, portion of the data payload, following the corrupt word, is error-free and transmits that portion as a separate and complete error-free packet also.", "The corrupt portion of the data payload is processed in standard error forwarding format-forming and transmitting a separate poisoned packet.", "Thus, according to the present invention, only the corrupt portion or portions of a PCI transaction need to be retransmitted.", "In cases where the data payload contains large amounts of PCI burst-mode data, system latencies and efficiency are optimized.", "[0029] The present invention is now described in greater detail with reference to FIG. 3 .", "FIG. 3 depicts a system 300 , according to the present invention, comprising the same constituent elements as system 100 .", "In reference to system 300 , however, function 110 is described in greater detail.", "Function 110 comprises a segregation structure 302 .", "Transaction data is routed through structure 302 .", "Structure 302 receives the write transaction data from link 114 , processes the transaction data, and loads it into a FIFO storage structure 304 —for eventual transmission, through the various protocol layers 306 of function 110 , onto target device 112 .", "As structure 302 processes data payload 210 , it evaluates the parity error status for each word of the payload, utilizing a suitable parity calculation function (not shown).", "Upon determining that a parity bit error has occurred for a specific data word, structure 300 halts processing of that data word.", "Structure 302 initiates transmission of the data already loaded into storage structure 304 as a complete packet—generating the necessary CRC and framing segments to complete that packet.", "This non-corrupt packet is transmitted on through the protocol layers 306 of function 110 to target device 112 .", "Structure 302 generates the necessary CRC and framing segments to form a complete packet from the corrupt data.", "This includes setting the EP field in header 208 to the required error transmission value.", "Structure 302 initiates transmission of the corrupt data packet to target device 112 , and retransmission of that data is then initiated.", "To the extent that any non-corrupt data follows the corrupt data, structure 302 initiates transmission of that non-corrupt data as a complete packet—generating the necessary CRC and framing segments.", "This non-corrupt packet is transmitted on through the protocol layers 306 of function 110 to target device 112 .", "[0030] Since PCI-X environment 104 provides for transaction reordering, the order in which structure 302 performs transmission of corrupt and non-corrupt packets may be varied, depending upon the specific requirements of a given system.", "In some embodiments, it may be advantageous for structure 302 to isolate the corrupt data, transmit it as a poisoned packet, and initiate retransmission of that data prior to processing the non-corrupt data that precedes and follows the corrupt data.", "In other embodiments, it may be advantageous for structure 302 to transmit the non-corrupt data packets first, before processing the corrupt data packet.", "These and other combinations and variations are comprehended by the present invention.", "[0031] The functions and structures described herein may be implemented in a number of ways—utilizing or combining a variety of hardware and software constructs.", "For example, structure 302 may be implemented in circuitry as a portion of a semiconductor device, or as a routine or algorithm operating on a processor.", "In some embodiments, structure 302 comprises its own separate parity calculation function.", "In other embodiments, structure 302 is communicatively linked with and utilizes a parity calculation function residing in some separate structure.", "In certain embodiments, structure 302 is implemented within a PCI slave portion of a bridge device.", "These and other similar combinations and variations are comprehended by the present invention.", "[0032] In another illustrative embodiment, the present invention is applied to transactions reading from a PCI environment to a PCI-X environment.", "Similar in many ways to system 100 , this embodiment is now described with reference to FIG. 4 .", "System 400 of FIG. 4 comprises an interface 402 between a PCI environment 404 and a PCI-X environment 406 .", "System 400 comprises a PCI-X-based function 408 , disposed “downstream”", "of a PCI-based function 410 (i.e., the PCI function 410 is in a host environment, PCI-X function 408 is in a peripheral environment).", "Functions 408 and 410 may comprise any physical or operational devices or structures (e.g., hardware, software) that operate in conformance with the present invention.", "In system 400 , function 408 serves as a bridge, providing much or most of the PCI to PCI-X translation functionality.", "[0033] In system 400 , some device 412 within the PCI-X environment 406 initiates a read transaction intended for function 410 .", "For example, function 410 may comprise system memory within an older, PCI computer to which a newer PCI-X peripheral 412 is attached.", "Device 412 is communicatively coupled to function 408 via link 414 .", "A communicative link 416 is established, through interface 402 , between function 408 and function 410 .", "Function 408 communicates the read request to function 410 , and begins receiving the data fetched from function 410 .", "[0034] Function 408 comprises a segregation structure 418 .", "Again, transaction data is routed through structure 418 .", "Structure 418 receives read transaction data from link 416 , processes the transaction data, and loads it into a FIFO storage structure 420 —for eventual transmission through the various protocol layers of function 408 to device 412 .", "As structure 418 processes the data payload, it evaluates the parity error status for each word of the payload, utilizing a suitable parity calculation function (not shown).", "Upon determining that a parity bit error has occurred for a specific data word, structure 418 halts processing of that data word.", "Structure 418 initiates transmission of the data already loaded into storage structure 420 as a complete packet—generating the necessary CRC and framing segments to complete that packet.", "Structure 418 sets the data completion field within the header to indicate to device 412 that this is a complete packet.", "This non-corrupt packet is transmitted on through the protocol layers to target device 412 .", "Structure 418 generates the necessary CRC and framing segments to form a complete packet from the corrupt data.", "This includes setting the EP field in header to the required error transmission value.", "Structure 418 initiates transmission of the corrupt data packet to target device 412 , and retransmission of that data is then initiated.", "To the extent that any non-corrupt data follows the corrupt data, structure 418 initiates transmission of that non-corrupt data as a complete packet.", "[0035] Again, since PCI-X environment 406 provides for reordering of data packets, the order in which structure 418 performs transmission of corrupt and non-corrupt packets may be varied, depending upon the specific requirements of a given system.", "In some embodiments, it may be advantageous for structure 418 to isolate the corrupt data, transmit it as a poisoned packet, and initiate retransmission of that data prior to processing the non-corrupt data that precedes and follows the corrupt data.", "In other embodiments, it may be advantageous for structure 418 to transmit the non-corrupt data packets first, before processing the corrupt data packet.", "These and other combinations and variations are comprehended by the present invention.", "[0036] The functions and structures described herein may be implemented in a number of ways—utilizing or combining a variety of hardware and software constructs.", "For example, structure 418 may be implemented in circuitry as a portion of a semiconductor device, or as a routine or algorithm operating on a processor.", "In some embodiments, structure 418 comprises its own separate parity calculation function.", "In other embodiments, structure 418 is communicatively linked with and utilizes a parity calculation function residing in some separate structure.", "[0037] The embodiments and examples set forth herein are presented to best explain the present invention and its practical application and to thereby enable those skilled in the art to make and utilize the invention.", "However, those skilled in the art will recognize that the foregoing description and examples have been presented for the purpose of illustration and example only.", "The description as set forth is not intended to be exhaustive or to limit the invention to the precise form disclosed.", "Many modifications and variations are possible in light of the above teaching without departing from the spirit and scope of the following claims." ]
CROSS-REFERENCE TO RELATED APPLICATION This application is a 35 USC 371 application of PCT/EP2008/051473 filed on Feb. 7, 2008. BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is based on a hand-held power tool. 2. Description of the Prior Art There is already a known hand-held power tool that has a transmission housing and a transmission unit equipped with a switch device. The switch device also has a switch spring and an actuating unit, which can be mounted in the transmission housing and is equipped with a transmitting element. ADVANTAGES AND SUMMARY OF THE INVENTION The invention is based on a hand-held power tool, in particular a rotary hammer and/or a hammer chisel, having a transmission housing and a transmission unit equipped with a switch device that has a switch spring and an actuating unit, which can be mounted in the transmission housing and is equipped with a transmitting element. According to one proposed embodiment, the switch spring has a receiving region provided to accommodate the transmitting element of the assembled actuating unit upon assembly of the transmission housing and transmission unit. In this context, the expression “assembly of the transmission housing and transmission unit” is understood in particular to mean a sliding of the transmission housing onto the transmission unit in a preferred assembly direction or a sliding of the transmission unit into the transmission housing in a preferred assembly direction. With the embodiment of the hand-held power tool according to the invention, it is possible to achieve a structurally simple mounting of the switch spring on the actuating unit during a simultaneous assembly of the transmission housing and transmission unit. This can be achieved in a particularly advantageous fashion if the switch spring has at least two spring legs that define the receiving region. Preferably, after an assembly of the transmission housing and transmission unit, the actuating unit is ready for operation, situated in a first switched position. The actuating unit is advantageously provided for switching between at least two different switched positions. According to another proposed embodiment, the two spring legs are spaced apart from each other perpendicular to an assembly direction, making it possible to achieve a low-wear insertion of the actuating unit into the receiving region of the switch spring. The term “assembly direction” here is understood in particular to mean a direction in which a translatory relative movement of the transmission housing in relation to the transmission unit occurs during assembly of the transmission housing with the transmission unit. If the spring legs are provided to move in an axial direction of at least one switch element of the transmission unit when the actuating unit is moved in a rotation direction, then this makes it possible to achieve an advantageous transformation of a switching motion, eliminating the need for additional parts. According to another proposed embodiment of the invention, the switch spring constitutes at least one energy storage mechanism in which a switching force can be stored, thus making it advantageously possible to achieve a particularly low-wear switching between two switch elements that have switched positions synchronous to each other. If the two switch elements are situated in a position in which they are rotationally offset from each other, the switching force can be advantageously stored in the switch spring until the two switch elements assume synchronous switched positions at which point one of the two switch elements can be slid toward the other switch element because of the stored switching force, thus permitting the two switch elements to engage with each other in order to carry out a torque transmission. According to another proposed embodiment of the invention, at least one spring leg of the switch spring has a switching bevel against which the transmitting element presses during at least one switching procedure, making it possible to achieve a structurally simple axial movement of a switch element connected to the switch spring during a rotating movement of the actuating unit. This can be achieved in a particularly advantageous fashion if the switching bevel of the spring leg has at least one guide surface for guiding the transmitting element. According to another proposed embodiment of the invention, the two spring legs each have a respective leg region and the two leg regions are situated in a region of the transmitting element, in a plane parallel to the assembly direction, permitting the transmitting element to transmit a movement, in particular a rotating movement of the actuating unit, to the switch spring or more precisely, the spring legs, in a particularly simple fashion. If the switch spring also has a subregion for accommodating a switch element of the transmission unit, then it is possible to advantageously achieve a direct coupling to the switch element, eliminating the need for additional parts. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of a preferred embodiment taken in conjunction with the drawings, in which: FIG. 1 shows a hand-held power tool according to the invention, equipped with a switch device, FIG. 2 shows a section through a subregion of the hand-held power tool, equipped with a transmission unit and a transmission housing, FIG. 3 is a side view of the switch device, FIG. 4 is a perspective view of the switch device, and FIG. 5 shows perspective views of the switch device and the transmission unit in a first switched position ( FIG. 5 a ) and in a second switched position ( FIG. 5 b ). DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a hand-held power tool 10 embodied in the form of a rotary hammer. The hand-held power tool 10 includes a housing 54 with a transmission housing 12 and, in a front region, a tool holder 56 for holding a tool. At an end oriented away from the front region, the hand-held power tool 10 has a main handle 58 for actuating the hand-held power tool 10 and for transmitting force from an operator to the hand-held power tool 10 . The hand-held power tool 10 has a drive unit 60 comprised of an electric motor to produce a drive moment. The drive torque of the drive unit 60 is transmitted via an intermediate shaft 62 of the hand-held power tool to an impact mechanism 64 , which is only partially shown in FIG. 2 for the sake of visibility, and/or to a rotating output element constituted by a hammer tube 66 ( FIG. 2 ). In order to switch between different drive speeds and/or drive modes of a tool in the tool holder 56 , the hand-held power tool 10 has a switch device 16 equipped with an actuating unit 20 that includes a selector knob 68 . FIG. 2 shows a subregion of the handheld power tool 10 , having a transmission unit 14 with the switch device 16 and having the transmission housing 12 . The switch device 16 for switching between different transmission stages of the transmission unit 14 has a switch spring 18 and the actuating unit mounted in the transmission housing 12 . To this end, the switch spring 18 transmits a rotating movement of the actuating unit 20 to an axially movable switch element 36 embodied in the form of a switching plate belonging to the transmission unit 14 . The switch spring 18 has two spring legs 26 , 28 that define a receiving region 24 for accommodating a transmitting element 22 of the actuating unit 20 . The transmitting element 22 is embodied in the shape of a bar and is situated on the actuating unit 20 , extending in a direction of a rotation axis 72 of the actuating unit 20 , eccentric to the rotation axis 72 , on an inner side 70 of the actuating unit 20 oriented away from the selector knob 68 ( FIGS. 2 and 3 ). When the operator of the hand-held power tool 10 actuates the switch or more precisely, executes a rotating movement of the actuating unit 20 , the bar-shaped transmitting element 22 , which is arranged eccentric to the rotation axis 72 , transmits a force to one of the two spring legs 26 , 28 of the switch spring 18 ( FIGS. 2 through 5 ). Upon assembly of the transmission housing 12 and the transmission unit 14 in an assembly direction 30 pointing perpendicularly into the plane of the drawing in FIG. 2 , the receiving region 24 for accommodating the transmitting element 22 makes it possible to move the transmission housing 12 in relation to the transmission unit 14 and to slide the transmission housing 12 , together with the actuating unit 20 that has already been mounted into it, onto the transmission unit 14 . To this end, the two spring legs 26 , 28 of the switch spring 18 are spaced apart from each other perpendicular to the assembly direction 30 . The two spring legs 26 , 28 are thus spaced apart from each other in a direction 74 that is oriented essentially perpendicular to the rotation axis 72 and perpendicular to the assembly direction 30 . In addition, the two spring legs 26 , 28 are situated spaced apart from each other parallel to the rotation axis 72 . In order for the switch spring 18 to transmit a force to the switch element 36 during a switching movement or more precisely during a rotating movement of the actuating unit 20 , the switch spring 18 has a subregion 52 composed of a helical spring ( FIGS. 2 through 4 ). The subregion 52 with the helical spring here encloses a receiving region for accommodating the switch element 36 . To this end, the switch element 36 has a bar-shaped coupling element 76 on a side 78 oriented toward the actuating unit 20 ( FIG. 3 ). The two spring legs 26 , 28 each have a respective first leg region 80 , 82 that extends in the direction 74 from the subregion 52 with the helical spring ( FIGS. 3 through 5 ). The first leg region 80 of the first spring leg 26 in the assembly direction 30 is longer in the direction 74 than the first leg region 82 of the second spring leg 28 in the assembly direction 30 . The first leg region 82 of the second spring leg 28 is adjoined by a second leg region 84 , which is perpendicular to the first leg region 82 and extends toward the actuating element 20 in a direction of a superposition of the assembly direction 30 and the rotation axis 72 . In addition, the second spring leg 28 has a third leg region 86 that adjoins the second leg region 84 and extends perpendicular to the second leg region 84 in the direction 74 . The third leg region 86 rests against the transmitting element 22 of the actuating unit 20 , after the transmitting element 22 in the assembly direction 30 . The first leg region 80 of the first spring leg 26 is perpendicularly adjoined by a second leg region 88 that extends parallel to the rotation axis 72 , toward the actuating unit 20 . The second leg region 88 of the first spring leg 26 is perpendicularly adjoined by a third leg region 90 that extends at first parallel to the assembly direction 30 . The third leg region 90 of the first spring leg 26 also includes a switching bevel 42 that, in addition to a span component oriented in the assembly direction 30 , has a span component oriented in the direction 74 . The third leg region 90 is adjoined by a fourth leg region 92 of the first spring leg 26 that extends in direction 74 . The fourth leg region 92 of the first spring leg 26 and the third leg region 86 of the second spring leg 28 are essentially situated in a plane that extends parallel to the assembly direction 30 . When an operator of the hand-held power tool 10 actuates the switch or more precisely, moves the actuating unit 20 in a rotation direction 32 , the switch spring 18 moves the switch element 36 in an axial direction 34 . To this end, the switch element 36 is supported so that it is able to move on a guide rod 94 of the transmission unit 14 in the axial direction 34 , which extends parallel to the assembly direction 30 ( FIGS. 5 a and 5 b ). The switch element 36 has two annular regions 96 that are provided to accommodate the guide rod 94 . The two regions 96 are situated on the switch element 36 , one after the other along the guide rod 94 . In order to limit a movement of the switch element 36 on the guide rod 94 in a direction 98 , the guide rod 94 is equipped with a stop element 100 embodied in the form of a snap ring that is affixed to the guide rod 94 . The switch element 36 also has a coupling region 102 provided for coupling it to the transmission element 104 of the transmission unit 14 embodied in the form of a gear unit ( FIGS. 3 through 5 ). The transmission element 104 of the transmission unit is supported so that it is able to move in the axial direction 34 on the intermediate shaft 62 in order to switch between the different transmission stages. To permit a coupling of the switch element 36 to the transmission element 104 , the transmission element 104 has a receiving groove 106 that is engaged by the coupling region 102 of the switch element 36 . To guide and support the two spring legs 26 , 28 on the switch element 36 , the switch element 36 has a subregion 108 that extends essentially parallel to the assembly direction 30 and essentially parallel to the rotation axis 72 . The two spring legs 26 , 28 are guided between the subregion 108 and the guide rod 94 . In the axial direction 34 , the switch element 36 also has a lateral flank 110 on both a side oriented toward the stop element 100 and a side oriented away from the stop element 100 ; these flanks, together with the subregion 108 and the guide rod 94 , hold the two spring legs 26 , 28 in a desired position. FIG. 5 a shows a first switched position of the actuating unit 20 and the switch element 36 on the guide rod 94 . In the first switched position, the transmitting element 22 of the actuating unit 20 rests against the third leg region 86 of the second spring leg 28 . The switch element 36 here is situated in an end position resting against the stop element 100 on the guide rod 94 . The transmission element 104 of the transmission unit 14 has one gear 112 for transmitting a drive moment to the hammer tube 66 and a second gear 114 , which, in a second switched position of the switch element 36 and actuating unit 20 , can be coupled to a second gear unit 116 of the transmission unit 14 that is rotatably supported on the intermediate shaft 62 . With a rotation of the actuating unit 20 in the rotation direction 32 from a first switched position into a second switched position ( FIGS. 5 a and 5 b ), the transmitting element 22 of the actuating unit 20 moves along an arc toward the third leg region 90 of the first spring leg 26 . As soon as the transmitting element 22 comes into contact with the switching bevel 42 of the third leg region 90 , the transmitting element 22 exerts a pressure in the direction opposite from the direction 98 on the first spring leg 26 , causing the switch spring 18 and the switch element 36 to move on the guide rod 94 in the axial direction 34 opposite from the direction 98 . On a side oriented toward the transmitting element 22 , the switching bevel 42 has a guide surface 44 that guides the transmitting element 22 into the second switched position while at the same time, the switch element 36 moves farther on the guide rod 94 in the direction opposite from the direction 98 . If the actuating unit 20 and the transmitting element 22 are situated in the second switched position ( FIG. 5 b ), then the fourth leg region 92 of the first spring leg 26 rests against the transmitting element 22 , thus preventing the switch spring 18 and switch element 36 from moving back out of the second switched position in an undesirable fashion. In the second switched position, the second gear 114 of the transmission element 104 engages with an inner contour 118 of the second gear unit 116 that corresponds to the second gear 114 . When switching from the first switched position into the second switched position, if a switching path of the switch element 36 is blocked—i.e. the second gear 114 of the transmission element 104 and the inner contour 118 are in a rotationally offset position in relation to each other that prevents the second gear 114 from engaging in the inner contour 118 —then the switch spring 18 functions as an energy storage means 38 in which a switching force for moving the transmission element 104 into the second switched position can be stored. As soon as the switching path is free—i.e. the second gear 114 and the inner contour 118 of the second gear unit 116 are in a coinciding, synchronous position—the movement energy of the switch spring 18 is then transmitted to the switch element 36 so that the switch element 36 , together with the transmission element 104 , is moved farther in the direction opposite from the direction 98 and the second gear 114 engages with an inner contour 118 of the second gear unit 116 . If the actuating unit 20 is rotated from the second switched position into the first switched position in the rotation direction 32 , then the transmitting element 22 presses against the third leg region 86 of the second spring leg 28 , thus moving the switch spring 18 —and together with it, the switch element 36 on the guide rod 94 and the transmission element 104 on the intermediate shaft 62 —in the direction 98 . During the switching procedure, the transmitting element 22 moves from an end region of the third leg region 86 remote from the second leg region 84 of the second spring leg 28 to an end region of the third leg region 86 close to the second leg region 84 . If the actuating unit 20 and the transmitting element 22 are in the first switched position, then the switch element 36 on the guide rod 94 is in the end position oriented closer to the stop element 100 . The foregoing relates to the preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.
The invention relates to a hand machine tool, in particular, a hammer drill or chisel, having a gearbox housing and a gearbox unit with a switching device. The switching device includes a switching spring and an operating unit which may be mounted in the gearbox housing with a transfer element. According to the invention, the switching spring has a housing region provided for housing the transfer element of the assembled operating unit, on assembly of the gearbox housing and the gearbox unit.
Condense the core contents of the given document.
[ "CROSS-REFERENCE TO RELATED APPLICATION This application is a 35 USC 371 application of PCT/EP2008/051473 filed on Feb. 7, 2008.", "BACKGROUND OF THE INVENTION 1.", "Field of the Invention The invention is based on a hand-held power tool.", "Description of the Prior Art There is already a known hand-held power tool that has a transmission housing and a transmission unit equipped with a switch device.", "The switch device also has a switch spring and an actuating unit, which can be mounted in the transmission housing and is equipped with a transmitting element.", "ADVANTAGES AND SUMMARY OF THE INVENTION The invention is based on a hand-held power tool, in particular a rotary hammer and/or a hammer chisel, having a transmission housing and a transmission unit equipped with a switch device that has a switch spring and an actuating unit, which can be mounted in the transmission housing and is equipped with a transmitting element.", "According to one proposed embodiment, the switch spring has a receiving region provided to accommodate the transmitting element of the assembled actuating unit upon assembly of the transmission housing and transmission unit.", "In this context, the expression “assembly of the transmission housing and transmission unit”", "is understood in particular to mean a sliding of the transmission housing onto the transmission unit in a preferred assembly direction or a sliding of the transmission unit into the transmission housing in a preferred assembly direction.", "With the embodiment of the hand-held power tool according to the invention, it is possible to achieve a structurally simple mounting of the switch spring on the actuating unit during a simultaneous assembly of the transmission housing and transmission unit.", "This can be achieved in a particularly advantageous fashion if the switch spring has at least two spring legs that define the receiving region.", "Preferably, after an assembly of the transmission housing and transmission unit, the actuating unit is ready for operation, situated in a first switched position.", "The actuating unit is advantageously provided for switching between at least two different switched positions.", "According to another proposed embodiment, the two spring legs are spaced apart from each other perpendicular to an assembly direction, making it possible to achieve a low-wear insertion of the actuating unit into the receiving region of the switch spring.", "The term “assembly direction”", "here is understood in particular to mean a direction in which a translatory relative movement of the transmission housing in relation to the transmission unit occurs during assembly of the transmission housing with the transmission unit.", "If the spring legs are provided to move in an axial direction of at least one switch element of the transmission unit when the actuating unit is moved in a rotation direction, then this makes it possible to achieve an advantageous transformation of a switching motion, eliminating the need for additional parts.", "According to another proposed embodiment of the invention, the switch spring constitutes at least one energy storage mechanism in which a switching force can be stored, thus making it advantageously possible to achieve a particularly low-wear switching between two switch elements that have switched positions synchronous to each other.", "If the two switch elements are situated in a position in which they are rotationally offset from each other, the switching force can be advantageously stored in the switch spring until the two switch elements assume synchronous switched positions at which point one of the two switch elements can be slid toward the other switch element because of the stored switching force, thus permitting the two switch elements to engage with each other in order to carry out a torque transmission.", "According to another proposed embodiment of the invention, at least one spring leg of the switch spring has a switching bevel against which the transmitting element presses during at least one switching procedure, making it possible to achieve a structurally simple axial movement of a switch element connected to the switch spring during a rotating movement of the actuating unit.", "This can be achieved in a particularly advantageous fashion if the switching bevel of the spring leg has at least one guide surface for guiding the transmitting element.", "According to another proposed embodiment of the invention, the two spring legs each have a respective leg region and the two leg regions are situated in a region of the transmitting element, in a plane parallel to the assembly direction, permitting the transmitting element to transmit a movement, in particular a rotating movement of the actuating unit, to the switch spring or more precisely, the spring legs, in a particularly simple fashion.", "If the switch spring also has a subregion for accommodating a switch element of the transmission unit, then it is possible to advantageously achieve a direct coupling to the switch element, eliminating the need for additional parts.", "BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of a preferred embodiment taken in conjunction with the drawings, in which: FIG. 1 shows a hand-held power tool according to the invention, equipped with a switch device, FIG. 2 shows a section through a subregion of the hand-held power tool, equipped with a transmission unit and a transmission housing, FIG. 3 is a side view of the switch device, FIG. 4 is a perspective view of the switch device, and FIG. 5 shows perspective views of the switch device and the transmission unit in a first switched position ( FIG. 5 a ) and in a second switched position ( FIG. 5 b ).", "DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a hand-held power tool 10 embodied in the form of a rotary hammer.", "The hand-held power tool 10 includes a housing 54 with a transmission housing 12 and, in a front region, a tool holder 56 for holding a tool.", "At an end oriented away from the front region, the hand-held power tool 10 has a main handle 58 for actuating the hand-held power tool 10 and for transmitting force from an operator to the hand-held power tool 10 .", "The hand-held power tool 10 has a drive unit 60 comprised of an electric motor to produce a drive moment.", "The drive torque of the drive unit 60 is transmitted via an intermediate shaft 62 of the hand-held power tool to an impact mechanism 64 , which is only partially shown in FIG. 2 for the sake of visibility, and/or to a rotating output element constituted by a hammer tube 66 ( FIG. 2 ).", "In order to switch between different drive speeds and/or drive modes of a tool in the tool holder 56 , the hand-held power tool 10 has a switch device 16 equipped with an actuating unit 20 that includes a selector knob 68 .", "FIG. 2 shows a subregion of the handheld power tool 10 , having a transmission unit 14 with the switch device 16 and having the transmission housing 12 .", "The switch device 16 for switching between different transmission stages of the transmission unit 14 has a switch spring 18 and the actuating unit mounted in the transmission housing 12 .", "To this end, the switch spring 18 transmits a rotating movement of the actuating unit 20 to an axially movable switch element 36 embodied in the form of a switching plate belonging to the transmission unit 14 .", "The switch spring 18 has two spring legs 26 , 28 that define a receiving region 24 for accommodating a transmitting element 22 of the actuating unit 20 .", "The transmitting element 22 is embodied in the shape of a bar and is situated on the actuating unit 20 , extending in a direction of a rotation axis 72 of the actuating unit 20 , eccentric to the rotation axis 72 , on an inner side 70 of the actuating unit 20 oriented away from the selector knob 68 ( FIGS. 2 and 3 ).", "When the operator of the hand-held power tool 10 actuates the switch or more precisely, executes a rotating movement of the actuating unit 20 , the bar-shaped transmitting element 22 , which is arranged eccentric to the rotation axis 72 , transmits a force to one of the two spring legs 26 , 28 of the switch spring 18 ( FIGS. 2 through 5 ).", "Upon assembly of the transmission housing 12 and the transmission unit 14 in an assembly direction 30 pointing perpendicularly into the plane of the drawing in FIG. 2 , the receiving region 24 for accommodating the transmitting element 22 makes it possible to move the transmission housing 12 in relation to the transmission unit 14 and to slide the transmission housing 12 , together with the actuating unit 20 that has already been mounted into it, onto the transmission unit 14 .", "To this end, the two spring legs 26 , 28 of the switch spring 18 are spaced apart from each other perpendicular to the assembly direction 30 .", "The two spring legs 26 , 28 are thus spaced apart from each other in a direction 74 that is oriented essentially perpendicular to the rotation axis 72 and perpendicular to the assembly direction 30 .", "In addition, the two spring legs 26 , 28 are situated spaced apart from each other parallel to the rotation axis 72 .", "In order for the switch spring 18 to transmit a force to the switch element 36 during a switching movement or more precisely during a rotating movement of the actuating unit 20 , the switch spring 18 has a subregion 52 composed of a helical spring ( FIGS. 2 through 4 ).", "The subregion 52 with the helical spring here encloses a receiving region for accommodating the switch element 36 .", "To this end, the switch element 36 has a bar-shaped coupling element 76 on a side 78 oriented toward the actuating unit 20 ( FIG. 3 ).", "The two spring legs 26 , 28 each have a respective first leg region 80 , 82 that extends in the direction 74 from the subregion 52 with the helical spring ( FIGS. 3 through 5 ).", "The first leg region 80 of the first spring leg 26 in the assembly direction 30 is longer in the direction 74 than the first leg region 82 of the second spring leg 28 in the assembly direction 30 .", "The first leg region 82 of the second spring leg 28 is adjoined by a second leg region 84 , which is perpendicular to the first leg region 82 and extends toward the actuating element 20 in a direction of a superposition of the assembly direction 30 and the rotation axis 72 .", "In addition, the second spring leg 28 has a third leg region 86 that adjoins the second leg region 84 and extends perpendicular to the second leg region 84 in the direction 74 .", "The third leg region 86 rests against the transmitting element 22 of the actuating unit 20 , after the transmitting element 22 in the assembly direction 30 .", "The first leg region 80 of the first spring leg 26 is perpendicularly adjoined by a second leg region 88 that extends parallel to the rotation axis 72 , toward the actuating unit 20 .", "The second leg region 88 of the first spring leg 26 is perpendicularly adjoined by a third leg region 90 that extends at first parallel to the assembly direction 30 .", "The third leg region 90 of the first spring leg 26 also includes a switching bevel 42 that, in addition to a span component oriented in the assembly direction 30 , has a span component oriented in the direction 74 .", "The third leg region 90 is adjoined by a fourth leg region 92 of the first spring leg 26 that extends in direction 74 .", "The fourth leg region 92 of the first spring leg 26 and the third leg region 86 of the second spring leg 28 are essentially situated in a plane that extends parallel to the assembly direction 30 .", "When an operator of the hand-held power tool 10 actuates the switch or more precisely, moves the actuating unit 20 in a rotation direction 32 , the switch spring 18 moves the switch element 36 in an axial direction 34 .", "To this end, the switch element 36 is supported so that it is able to move on a guide rod 94 of the transmission unit 14 in the axial direction 34 , which extends parallel to the assembly direction 30 ( FIGS. 5 a and 5 b ).", "The switch element 36 has two annular regions 96 that are provided to accommodate the guide rod 94 .", "The two regions 96 are situated on the switch element 36 , one after the other along the guide rod 94 .", "In order to limit a movement of the switch element 36 on the guide rod 94 in a direction 98 , the guide rod 94 is equipped with a stop element 100 embodied in the form of a snap ring that is affixed to the guide rod 94 .", "The switch element 36 also has a coupling region 102 provided for coupling it to the transmission element 104 of the transmission unit 14 embodied in the form of a gear unit ( FIGS. 3 through 5 ).", "The transmission element 104 of the transmission unit is supported so that it is able to move in the axial direction 34 on the intermediate shaft 62 in order to switch between the different transmission stages.", "To permit a coupling of the switch element 36 to the transmission element 104 , the transmission element 104 has a receiving groove 106 that is engaged by the coupling region 102 of the switch element 36 .", "To guide and support the two spring legs 26 , 28 on the switch element 36 , the switch element 36 has a subregion 108 that extends essentially parallel to the assembly direction 30 and essentially parallel to the rotation axis 72 .", "The two spring legs 26 , 28 are guided between the subregion 108 and the guide rod 94 .", "In the axial direction 34 , the switch element 36 also has a lateral flank 110 on both a side oriented toward the stop element 100 and a side oriented away from the stop element 100 ;", "these flanks, together with the subregion 108 and the guide rod 94 , hold the two spring legs 26 , 28 in a desired position.", "FIG. 5 a shows a first switched position of the actuating unit 20 and the switch element 36 on the guide rod 94 .", "In the first switched position, the transmitting element 22 of the actuating unit 20 rests against the third leg region 86 of the second spring leg 28 .", "The switch element 36 here is situated in an end position resting against the stop element 100 on the guide rod 94 .", "The transmission element 104 of the transmission unit 14 has one gear 112 for transmitting a drive moment to the hammer tube 66 and a second gear 114 , which, in a second switched position of the switch element 36 and actuating unit 20 , can be coupled to a second gear unit 116 of the transmission unit 14 that is rotatably supported on the intermediate shaft 62 .", "With a rotation of the actuating unit 20 in the rotation direction 32 from a first switched position into a second switched position ( FIGS. 5 a and 5 b ), the transmitting element 22 of the actuating unit 20 moves along an arc toward the third leg region 90 of the first spring leg 26 .", "As soon as the transmitting element 22 comes into contact with the switching bevel 42 of the third leg region 90 , the transmitting element 22 exerts a pressure in the direction opposite from the direction 98 on the first spring leg 26 , causing the switch spring 18 and the switch element 36 to move on the guide rod 94 in the axial direction 34 opposite from the direction 98 .", "On a side oriented toward the transmitting element 22 , the switching bevel 42 has a guide surface 44 that guides the transmitting element 22 into the second switched position while at the same time, the switch element 36 moves farther on the guide rod 94 in the direction opposite from the direction 98 .", "If the actuating unit 20 and the transmitting element 22 are situated in the second switched position ( FIG. 5 b ), then the fourth leg region 92 of the first spring leg 26 rests against the transmitting element 22 , thus preventing the switch spring 18 and switch element 36 from moving back out of the second switched position in an undesirable fashion.", "In the second switched position, the second gear 114 of the transmission element 104 engages with an inner contour 118 of the second gear unit 116 that corresponds to the second gear 114 .", "When switching from the first switched position into the second switched position, if a switching path of the switch element 36 is blocked—i.e. the second gear 114 of the transmission element 104 and the inner contour 118 are in a rotationally offset position in relation to each other that prevents the second gear 114 from engaging in the inner contour 118 —then the switch spring 18 functions as an energy storage means 38 in which a switching force for moving the transmission element 104 into the second switched position can be stored.", "As soon as the switching path is free—i.e. the second gear 114 and the inner contour 118 of the second gear unit 116 are in a coinciding, synchronous position—the movement energy of the switch spring 18 is then transmitted to the switch element 36 so that the switch element 36 , together with the transmission element 104 , is moved farther in the direction opposite from the direction 98 and the second gear 114 engages with an inner contour 118 of the second gear unit 116 .", "If the actuating unit 20 is rotated from the second switched position into the first switched position in the rotation direction 32 , then the transmitting element 22 presses against the third leg region 86 of the second spring leg 28 , thus moving the switch spring 18 —and together with it, the switch element 36 on the guide rod 94 and the transmission element 104 on the intermediate shaft 62 —in the direction 98 .", "During the switching procedure, the transmitting element 22 moves from an end region of the third leg region 86 remote from the second leg region 84 of the second spring leg 28 to an end region of the third leg region 86 close to the second leg region 84 .", "If the actuating unit 20 and the transmitting element 22 are in the first switched position, then the switch element 36 on the guide rod 94 is in the end position oriented closer to the stop element 100 .", "The foregoing relates to the preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims." ]
FIELD OF THE INVENTION The present invention relates to a device for assisted gear shifting of a transmission. More particularly, the present invention is intended to be utilized for assisted gear shifting of a transmission belonging to a boat motor. BACKGROUND OF THE INVENTION In connection with driving arrangements for water vessels, for example in the form of motor driven leisure craft having outboard drives, an outboard drive is normally used which comprises a transmission for connecting the output shaft of the boat engine to the boat propeller shaft. The transmission may be utilized, in a known manner, to change the rotational direction of the propeller. More precisely, an adjustable gear shift control may be utilized to set the transmission in a certain operating mode which constitutes a position corresponding to forward propulsion of the boat, a position corresponding to rearward or reverse propulsion of the boat, or a neutral position. A known transmission for outboard drives comprises a driving cogwheel which is arranged so that it is rotated by the engine's output shaft and which transfers the power of the engine to a propeller shaft through either one of two driven cogwheels which are axially spaced apart on a vertical axle, which, in turn, is connected to the propeller shaft. For this purpose, the transmission comprises an adjustable coupling arrangement which consists of a conical clutch arranged in connection with the vertical axle. Using this clutch arrangement, one of the two driven cogwheels may be connected so that a mechanical connection is established from the engine shaft to the propeller shaft. The direction of rotation of the propeller shaft will then depend on which of the two driven cogwheels that is connected. If neither of the two driven cogwheels is connected, the neutral position is engaged. Furthermore, the gear shift control is connected to the conical clutch by means of a mechanical push-pull wire whose inner core is influenced in a known manner either forwards or backwards when turning the gear shift control in the corresponding direction. In this manner, the transmission may be set to the desired mode of operation. One drawback in connection with known transmissions exists in those cases when a particularly high torque is transmitted (more exactly a torque in the order of 50 Nm or higher). In such cases, a high resistance can be felt in the control during shifting of the transmission from forward to reverse or to the neutral position. This is due to the fact that the torque, which is generated by the propeller when the forward or backward position is engaged, causes a certain resistance against the axial movement of the conical clutch which is required for the transmission to be shifted from forward to rearward operation and to the neutral position. According to a known technique, the above mentioned problem may be solved by regulating the engine in such a way that the ignition is temporarily interrupted for one or more of its cylinders when a high resistance to shifting is present. In this way, an assisted shifting is obtained in which a strongly reduced resistance is experienced. A previously known device which provides such an assisted shifting for a transmission of a boat engine is shown in the patent U.S. Pat. No. 4,525,149. This device comprises a pivotingly suspended shifting link which may be operated by a lever for setting a reversing gear in a forward, backward or neutral position. The device further comprises a push-pull wire which is connected between a lever and a further pivotable means, which in turn is attached to the shifting link by means of a special linking means which carries a displaceable component. This displaceable component is spring biased with a certain force which corresponds to a predetermined resistance when shifting the reversing gear. Should a force exceeding this predetermined force be necessary for shifting, the displaceable component will cancel out the spring bias and be moved a small distance. This displacement may be detected using a position transducer, which will send a signal to the engine to interrupt the ignition to at least one engine cylinder. This will result in a lowered resistance during shifting. Although the above mentioned device in principle provides a satisfactory assisted shifting, it has certain shortcomings. Foremost is the fact that it is constructed from a large number of parts, of which a plurality are pivotably arranged on the boat engine. This creates a device having an unnecessarily complicated construction and too many parts. This constitutes a negative factor regarding wear, service and cost. A further disadvantage is that a mechanical play may develop where the wire of the lever is connected to the pivotable means. SUMMARY OF THE INVENTION An object of the present invention is to provide an improved device for assisted shifting of a transmission, especially for a boat engine, which comprises a small number of parts, has a simple and reliable construction and has an effective functioning. In accordance with the present invention, this and other objects have now been realized by the invention of apparatus for shifting a transmission coupled to an engine and including a controller for shifting the transmission between at least two operating modes, a control lever for switching the transmission, and an actuator for actuating the control lever in response to shifting of the controller, the apparatus comprising a first longitudinal member connected to the controller, a second longitudinal member connected to the actuator, the first longitudinal member being coaxial with the second longitudinal member, a detector for detecting relative displacement between the first and second longitudinal members, and a spring member acting between the first and second longitudinal members so as to prevent the relative displacement between the first and second longitudinal members until a force acting on one of the first and second longitudinal members exceeds the spring force of the spring member. In accordance with a preferred embodiment, the first longitudinal member is substantially tubular and the second longitudinal member comprises a substantially cylindrical slide member disposed within the first longitudinal member. In accordance with one embodiment of the apparatus of the present invention, the spring member comprises a screw-shaped spring disposed around the second longitudinal member and within the first longitudinal member. In accordance with another embodiment of the apparatus of the present invention, the first longitudinal member includes a first compression member and the second longitudinal member includes a second compression member, the spring member being disposed between the first and second compression members whereby the spring member is compressed between the first and second compression members when the force acting on the first and second longitudinal members exceeds the spring force of the spring member. In a preferred embodiment, the first longitudinal member is substantially tubular and the second longitudinal member comprises a substantially cylindrical slide member disposed within the first longitudinal member. In a preferred embodiment, the first longitudinal member includes a predetermined inner diameter, and the first compression member comprises a portion of the first longitudinal member having an inner diameter which is less than the predetermined inner diameter. In accordance with another embodiment of the apparatus of the present invention, the second longitudinal member includes a predetermined inner diameter, and the second compression member comprises a portion of the second longitudinal member having an outer diameter which is greater than the predetermined outer diameter. In accordance with another embodiment of the apparatus of the present invention, the detector comprises a position transducer, and the second longitudinal member includes at least one modified portion juxtaposed with the position transducer whereby the position transducer is adapted to detect the position of the at least one modified portion of the second longitudinal member. In accordance with another embodiment, the position transducer comprises an inductive position transducer. In accordance with another embodiment of the apparatus of the present invention, the first longitudinal member is directly connected to the controller. In accordance with another embodiment of the apparatus of the present invention, the second longitudinal member is connected to the control lever by means of the actuator, and the actuator includes an outer cover, the outer cover of the actuator being rigidly mounted with respect to the controller. The present invention is intended to be used for the assisted shifting of the transmission of an engine, and comprises a first means which is connected to a lever for shifting the transmission between at least two modes of operation, a second means connected, by means of an actuator, to a control device for shifting the transmission, a detector for detecting a displacement of the first means relative to the second means, and means for limiting the power of the engine if such displacement is detected. The present invention is characterized by the fact that the first means and the second means are arranged for coaxial movement relative to each other, and the device comprises a spring means arranged to prevent such movement when a force, which is smaller than the spring force of the spring means, is acting upon the first means, and to allow said movement when the acting force is greater than that spring force. Several advantages are achieved through the present invention. Foremost among them is the fact that the device according to the present invention has a small number of components, which results in low material, production and service costs. Furthermore, the present invention provides for completely coaxial movement of the first means relative the second means if the spring force is exceeded (i.e. movement of both means is substantially along a common axis), whilst it otherwise functions as a rigid connection between a lever and a transmission. Thus, it does not require a special arrangement for mounting in a boat, but constitutes, in principle, an extension of a wire which is attached to the above mentioned control means for the engine transmission. The device according to the present invention may further be arranged directly next to such a means, i.e. without any intermediate wire. This eliminates the risk of play at the attachment point of such a wire. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in greater detail by way of example only and with reference to a particular embodiment illustrated in the annexed drawings, in which: FIG. 1 is a side, elevational, schematic view, partly in cross-section, of a device according to the present invention; and FIG. 2 is a side, elevational, schematic view of the device according to the present invention arranged in connection with the gear shift control means of a boat. DETAILED DESCRIPTION In FIG. 1 a device 1 is shown somewhat schematically for assisted shifting of a transmission, according to the present invention. According to the preferred embodiment, the device 1 is intended to be used together with a boat engine (not shown) and is arranged next to a control means 2 for selecting the desired shifting position of the transmission. In a previously known manner, the control means 2 consists of a lever which is pivotably suspended in a console means 3 , by means of a pivot axle 4 . The console means 3 is, in turn, fixedly arranged, suitably in a construction 5 belonging to the control means 2 . The control means 2 may thus be pivoted forwards and backwards, according to what is indicated with the letters “F” and “R” in FIG. 1 . The control means 2 may be set either in a neutral position, which corresponds to an idling engine, or a position for forward propulsion (or alternatively for rearward propulsion) of the boat, i.e. for switching in a gear in the forward direction (or alternatively in a rearward direction). According to the above explanation, especially with engines providing high torque, a strong resistance may occur when switching from the forward or rearward position to the neutral position. For this reason, the device 1 according to the present invention is arranged to provide for assisted switching, i.e. facilitated switching from the forward or reverse position to the neutral position. For this purpose, the device 1 comprises a first means 1 in the form of a sleeve 6 which is connected to the control means 2 . The sleeve 6 is shaped in the form of a substantially cylindrical tube, one end part 7 of which is intended to be an attachment for an interlocking means 8 , which in turn is a connection between the control means 2 and the sleeve 6 . The interlocking means 8 is preferably a double screw, one end of which for this reason has threads which are screwed into internal threads in the end part 7 of the sleeve 6 and the other end of which is threaded in an axle bar 9 of the control means 2 . The sleeve 6 carries a second means in the form of a slide 10 which is axially slidable within the sleeve 6 , i.e. slidable in the longitudinal direction of the sleeve 6 . The slide 10 is substantially cylindrical and is designed having a plurality of different sections with different diameters. More specifically, the slide 10 comprises two sections, 11 and 12 , respectively, which have an outer diameter which is somewhat smaller than the inner diameter of the sleeve 6 . Between these sections, 11 and 12 , is a section 13 having a substantially smaller diameter, according to FIG. 1 . This last-mentioned section 13 is located such that its position corresponds to the location of a detector means 14 , which preferably consists of an inductive position detector. The detector 14 is mounted at a hole 15 through the periphery of the sleeve 6 with the help of a detector holder 16 , which is arranged on the sleeve 6 . The detector 14 is furthermore connected to a control unit (not shown) for the boat engine by means of an electrical connection 17 . This control unit is arranged in a conventional way to regulate the ignition of the engine cylinders. As is described in further detail below, the detector is arranged to detect whether the slide 10 is displaced axially, i.e. if the section 13 having a comparatively small diameter is moved to either side so that it no longer is situated directly in front of the detector 14 . If this is the case, the detector 14 will generate a signal to the engine control unit, which in turn causes the ignition to be switched off to at least one of the engine cylinders. The end of the slide 10 which is facing away from the control means 2 is shaped as a fitting for a wire 18 . The outer casing of the wire 18 is not shown in FIG. 1 . The end part 19 of the slide 10 is preferably shaped as a hexagonal grip which is protruding from the sleeve 6 and which furthermore comprises an internal, threaded hole 20 . In this way, the wire 18 may be fastened in the slide 10 and will then constitute an axial elongation of the slide 10 . The wire 18 is connected to the boat's shifting mechanism (not shown), which preferably comprises a transmission of an essentially known type and which has a vertical shaft on which two axially spaced apart, conical cogwheels are arranged, and the vertical shaft in turn is connected to the boat propeller shaft. Either of these cogwheels may be engaged with a driving cogwheel on the engine output shaft so that the engine power may be transferred to the propeller shaft. The shifting mode, i.e. the direction of rotation of the propeller shaft, is then determined by which one of the two driven cogwheels is engaged. If neither of these two cogwheels is engaged, the neutral position is at hand. From FIG. 1 it is apparent that the sleeve 6 carries a spring means 21 which runs around the slide 10 . The spring means 21 is held in place in a compressed state between a locking ring 22 , which is fastened in a corresponding internal groove 30 in the sleeve 6 , and an end piece 23 which is part of the slide 10 . This end piece 23 preferably consists of a cylindrical part having an outer diameter which is somewhat smaller than the inner diameter of the sleeve 6 . Furthermore, it is apparent from FIG. 1 that the slide 10 has an outer step 24 which is formed by a reduction of the diameter of the slide 10 . When the device is in the state which is shown in FIG. 1, the outer step 24 is situated in substantially the same axial position as the locking ring 22 . The sleeve 6 further has an inner step 25 which is formed by an increase of the inner diameter of the sleeve 6 . In the state shown in FIG. 1, the inner step 25 is situated in substantially the same axial position as the end piece 23 which is facing the spring means 21 . The inner surface of the end piece 23 is shaped so that it is somewhat bevelled at one end. In this manner, the end piece 23 may be fastened in the slide 10 by riveting on the end of the slide 10 , whereby the material of the end of the slide 10 will extend and lock the end part 23 against a surface which is defined by a further step 31 on the slide 10 . The functioning of the slide will now be described. If the control means 2 is not subject to any force in the “F” or “R” directions, the slide 10 will be situated in the position which is shown in FIG. 1, i.e. the part 13 of the slide 10 which has a relatively small outer diameter will be directly in front of the detector 14 . If the control means 2 is actuated in the “F” direction, the whole device 1 will primarily be displaced towards the left, during which a substantially rigid connection is present between the sleeve 6 and the slide 10 . During shifting, a certain shifting resistance may be felt when manoeuvering the control means 2 , as has been explained above. When this resistance exceeds a force which corresponds to the spring force supplied by the spring means 21 , the spring means 21 will start being compressed. More exactly, the spring means 21 will then be compressed between the inner step 25 of the sleeve 6 and the outer step 24 of the slide 10 . The sleeve 6 will thus be displaced axially relative the slide 10 so that the part 11 will approach a position in front of the detector 14 . As mentioned above, the detector suitably comprises an inductive position transducer of a known type. This type of transducer comprises an oscillator which emits an electromagnetic field which is affected by the possible presence of electrically conductive objects. When the slide 10 (which preferably is made of stainless steel) is displaced so that the part 11 approaches a position directly in front of the detector 14 , the electric field will be disturbed. This causes the detector 14 to deliver a signal to the engine control unit, which as mentioned above will cause the ignition to at least one of the engine cylinders to be switched off. Correspondingly, the control means 2 may be actuated in the “R” direction. When a low shifting resistance is present, a substantially rigid connection is present between the sleeve 6 and the slide 10 . At the shifting resistance which exceeds the spring force of the spring means 21 , the sleeve 6 will be displaced relative to the slide 10 while the spring means 21 will be compressed between the locking ring 22 and the end piece 23 . This will cause the section 12 of the slide 10 to be situated in front of the detector 14 . In an analogous manner to what has been explained above, the detector 14 will then deliver a signal to the engine control unit for switching off the ignition to at least one engine cylinder. FIG. 2 shows schematically how the invention may be mounted and used in a boat. The device 1 for assisted shifting is then connected to a wire 18 which, in turn, has an outer cover 26 which is fastened to special extension housing 27 . This extension housing 27 comprises a substantially cylindrical means to which the outer cover 26 is fixedly arranged. The extension housing 27 is, in turn, fixedly arranged in construction 5 , which belongs to the control means 2 and which in turn is fixedly arranged in the boat. Furthermore, the other end of the wire 18 is connected to a control means in the form of a control lever 28 which, in turn, is pivotably suspended, by means of an axle 29 , and is arranged to actuate a transmission (not shown) connected to the boat's engine. This transmission may, for example, be of the type whose functioning has been described above. In this way, the transmission may be changed between forwards, reverse, and neutral positions respectively. The device 1 according to the present invention may be assembled in the following manner. Firstly, the end piece 23 is put in position inside the sleeve 6 , i.e. at the part of the sleeve 6 which is furthest to the right, according to FIG. 1 . Thereafter, the spring means 21 is placed in the sleeve 6 , whereafter the locking ring 22 is locked in its inner groove. Thereafter, the slide 10 is put in place, and its end part is pressed through the end piece 23 . Finally, the end piece 23 is fixedly locked by riveting against the end of the slide 10 , as discussed above. The present invention is not limited to the embodiment described above and shown in the drawings, but may be varied within the scope of the appended claims. For example, the force which is obtained through the spring means 21 may be varied according to the amount of shifting resistance which is desirable before the slide 10 and the sleeve 6 will be displaced relative to each other. The sleeve 6 may furthermore be arranged in direct connection to the control means 2 (by means of the interlocking means 8 ) or be connected to the control means 2 by means of an intervening actuator means, for example a wire of the same type as wire 18 discussed above. The present invention may be used for both inboard as well as outboard drives. The invention may also be used in connection with shifting mechanisms which utilize a conical clutch, as described above, or alternatively a dog clutch or some other type of transmission. Although the term “boat” has been used above, the present invention is suitable for use in connection with both smaller pleasure crafts, larger ships and other water vessels where there is a need for assisted shifting of a transmission. The invention may, in principle, be used in other contexts than boats. The present invention may be used in connection with boats having one, two or more propellers and a corresponding number of propeller shafts. Concerning choices of material, the sleeve 6 is preferably made of aluminium or a suitable aluminium alloy. The slide 10 is, as mentioned above, preferably made of stainless steel. The present invention may be used in such a way that the regulating signal which is initiated by the detector 14 , and which switches off the ignition for at least one engine cylinder, is only valid for a certain limited time. This is a safety related advantage which makes it possible for the engine to still operate even if, for example, the detector 14 were to deliver a faulty signal. Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
An apparatus for shifting a transmission coupled to an engine including a controller for shifting the transmission between operating modes, a control lever for switching the transmission, and an actuator for actuating the control lever in response to shifting of the controller. The apparatus includes a longitudinal tube connected to the controller, a cylindrical slide connected to the actuator for actuating the control lever in response to shifting of the controller, the longitudinal tube being coaxial with the cylindrical slide, a detector for detecting relative displacement between the longitudinal tube and the cylindrical slide, and a spring acting between the longitudinal tube and the cylindrical slide to prevent relative displacement between them until a force acting on one of them exceeds the spring force of the spring.
Identify and summarize the most critical technical features from the given patent document.
[ "FIELD OF THE INVENTION The present invention relates to a device for assisted gear shifting of a transmission.", "More particularly, the present invention is intended to be utilized for assisted gear shifting of a transmission belonging to a boat motor.", "BACKGROUND OF THE INVENTION In connection with driving arrangements for water vessels, for example in the form of motor driven leisure craft having outboard drives, an outboard drive is normally used which comprises a transmission for connecting the output shaft of the boat engine to the boat propeller shaft.", "The transmission may be utilized, in a known manner, to change the rotational direction of the propeller.", "More precisely, an adjustable gear shift control may be utilized to set the transmission in a certain operating mode which constitutes a position corresponding to forward propulsion of the boat, a position corresponding to rearward or reverse propulsion of the boat, or a neutral position.", "A known transmission for outboard drives comprises a driving cogwheel which is arranged so that it is rotated by the engine's output shaft and which transfers the power of the engine to a propeller shaft through either one of two driven cogwheels which are axially spaced apart on a vertical axle, which, in turn, is connected to the propeller shaft.", "For this purpose, the transmission comprises an adjustable coupling arrangement which consists of a conical clutch arranged in connection with the vertical axle.", "Using this clutch arrangement, one of the two driven cogwheels may be connected so that a mechanical connection is established from the engine shaft to the propeller shaft.", "The direction of rotation of the propeller shaft will then depend on which of the two driven cogwheels that is connected.", "If neither of the two driven cogwheels is connected, the neutral position is engaged.", "Furthermore, the gear shift control is connected to the conical clutch by means of a mechanical push-pull wire whose inner core is influenced in a known manner either forwards or backwards when turning the gear shift control in the corresponding direction.", "In this manner, the transmission may be set to the desired mode of operation.", "One drawback in connection with known transmissions exists in those cases when a particularly high torque is transmitted (more exactly a torque in the order of 50 Nm or higher).", "In such cases, a high resistance can be felt in the control during shifting of the transmission from forward to reverse or to the neutral position.", "This is due to the fact that the torque, which is generated by the propeller when the forward or backward position is engaged, causes a certain resistance against the axial movement of the conical clutch which is required for the transmission to be shifted from forward to rearward operation and to the neutral position.", "According to a known technique, the above mentioned problem may be solved by regulating the engine in such a way that the ignition is temporarily interrupted for one or more of its cylinders when a high resistance to shifting is present.", "In this way, an assisted shifting is obtained in which a strongly reduced resistance is experienced.", "A previously known device which provides such an assisted shifting for a transmission of a boat engine is shown in the patent U.S. Pat. No. 4,525,149.", "This device comprises a pivotingly suspended shifting link which may be operated by a lever for setting a reversing gear in a forward, backward or neutral position.", "The device further comprises a push-pull wire which is connected between a lever and a further pivotable means, which in turn is attached to the shifting link by means of a special linking means which carries a displaceable component.", "This displaceable component is spring biased with a certain force which corresponds to a predetermined resistance when shifting the reversing gear.", "Should a force exceeding this predetermined force be necessary for shifting, the displaceable component will cancel out the spring bias and be moved a small distance.", "This displacement may be detected using a position transducer, which will send a signal to the engine to interrupt the ignition to at least one engine cylinder.", "This will result in a lowered resistance during shifting.", "Although the above mentioned device in principle provides a satisfactory assisted shifting, it has certain shortcomings.", "Foremost is the fact that it is constructed from a large number of parts, of which a plurality are pivotably arranged on the boat engine.", "This creates a device having an unnecessarily complicated construction and too many parts.", "This constitutes a negative factor regarding wear, service and cost.", "A further disadvantage is that a mechanical play may develop where the wire of the lever is connected to the pivotable means.", "SUMMARY OF THE INVENTION An object of the present invention is to provide an improved device for assisted shifting of a transmission, especially for a boat engine, which comprises a small number of parts, has a simple and reliable construction and has an effective functioning.", "In accordance with the present invention, this and other objects have now been realized by the invention of apparatus for shifting a transmission coupled to an engine and including a controller for shifting the transmission between at least two operating modes, a control lever for switching the transmission, and an actuator for actuating the control lever in response to shifting of the controller, the apparatus comprising a first longitudinal member connected to the controller, a second longitudinal member connected to the actuator, the first longitudinal member being coaxial with the second longitudinal member, a detector for detecting relative displacement between the first and second longitudinal members, and a spring member acting between the first and second longitudinal members so as to prevent the relative displacement between the first and second longitudinal members until a force acting on one of the first and second longitudinal members exceeds the spring force of the spring member.", "In accordance with a preferred embodiment, the first longitudinal member is substantially tubular and the second longitudinal member comprises a substantially cylindrical slide member disposed within the first longitudinal member.", "In accordance with one embodiment of the apparatus of the present invention, the spring member comprises a screw-shaped spring disposed around the second longitudinal member and within the first longitudinal member.", "In accordance with another embodiment of the apparatus of the present invention, the first longitudinal member includes a first compression member and the second longitudinal member includes a second compression member, the spring member being disposed between the first and second compression members whereby the spring member is compressed between the first and second compression members when the force acting on the first and second longitudinal members exceeds the spring force of the spring member.", "In a preferred embodiment, the first longitudinal member is substantially tubular and the second longitudinal member comprises a substantially cylindrical slide member disposed within the first longitudinal member.", "In a preferred embodiment, the first longitudinal member includes a predetermined inner diameter, and the first compression member comprises a portion of the first longitudinal member having an inner diameter which is less than the predetermined inner diameter.", "In accordance with another embodiment of the apparatus of the present invention, the second longitudinal member includes a predetermined inner diameter, and the second compression member comprises a portion of the second longitudinal member having an outer diameter which is greater than the predetermined outer diameter.", "In accordance with another embodiment of the apparatus of the present invention, the detector comprises a position transducer, and the second longitudinal member includes at least one modified portion juxtaposed with the position transducer whereby the position transducer is adapted to detect the position of the at least one modified portion of the second longitudinal member.", "In accordance with another embodiment, the position transducer comprises an inductive position transducer.", "In accordance with another embodiment of the apparatus of the present invention, the first longitudinal member is directly connected to the controller.", "In accordance with another embodiment of the apparatus of the present invention, the second longitudinal member is connected to the control lever by means of the actuator, and the actuator includes an outer cover, the outer cover of the actuator being rigidly mounted with respect to the controller.", "The present invention is intended to be used for the assisted shifting of the transmission of an engine, and comprises a first means which is connected to a lever for shifting the transmission between at least two modes of operation, a second means connected, by means of an actuator, to a control device for shifting the transmission, a detector for detecting a displacement of the first means relative to the second means, and means for limiting the power of the engine if such displacement is detected.", "The present invention is characterized by the fact that the first means and the second means are arranged for coaxial movement relative to each other, and the device comprises a spring means arranged to prevent such movement when a force, which is smaller than the spring force of the spring means, is acting upon the first means, and to allow said movement when the acting force is greater than that spring force.", "Several advantages are achieved through the present invention.", "Foremost among them is the fact that the device according to the present invention has a small number of components, which results in low material, production and service costs.", "Furthermore, the present invention provides for completely coaxial movement of the first means relative the second means if the spring force is exceeded (i.e. movement of both means is substantially along a common axis), whilst it otherwise functions as a rigid connection between a lever and a transmission.", "Thus, it does not require a special arrangement for mounting in a boat, but constitutes, in principle, an extension of a wire which is attached to the above mentioned control means for the engine transmission.", "The device according to the present invention may further be arranged directly next to such a means, i.e. without any intermediate wire.", "This eliminates the risk of play at the attachment point of such a wire.", "BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in greater detail by way of example only and with reference to a particular embodiment illustrated in the annexed drawings, in which: FIG. 1 is a side, elevational, schematic view, partly in cross-section, of a device according to the present invention;", "and FIG. 2 is a side, elevational, schematic view of the device according to the present invention arranged in connection with the gear shift control means of a boat.", "DETAILED DESCRIPTION In FIG. 1 a device 1 is shown somewhat schematically for assisted shifting of a transmission, according to the present invention.", "According to the preferred embodiment, the device 1 is intended to be used together with a boat engine (not shown) and is arranged next to a control means 2 for selecting the desired shifting position of the transmission.", "In a previously known manner, the control means 2 consists of a lever which is pivotably suspended in a console means 3 , by means of a pivot axle 4 .", "The console means 3 is, in turn, fixedly arranged, suitably in a construction 5 belonging to the control means 2 .", "The control means 2 may thus be pivoted forwards and backwards, according to what is indicated with the letters “F”", "and “R”", "in FIG. 1 .", "The control means 2 may be set either in a neutral position, which corresponds to an idling engine, or a position for forward propulsion (or alternatively for rearward propulsion) of the boat, i.e. for switching in a gear in the forward direction (or alternatively in a rearward direction).", "According to the above explanation, especially with engines providing high torque, a strong resistance may occur when switching from the forward or rearward position to the neutral position.", "For this reason, the device 1 according to the present invention is arranged to provide for assisted switching, i.e. facilitated switching from the forward or reverse position to the neutral position.", "For this purpose, the device 1 comprises a first means 1 in the form of a sleeve 6 which is connected to the control means 2 .", "The sleeve 6 is shaped in the form of a substantially cylindrical tube, one end part 7 of which is intended to be an attachment for an interlocking means 8 , which in turn is a connection between the control means 2 and the sleeve 6 .", "The interlocking means 8 is preferably a double screw, one end of which for this reason has threads which are screwed into internal threads in the end part 7 of the sleeve 6 and the other end of which is threaded in an axle bar 9 of the control means 2 .", "The sleeve 6 carries a second means in the form of a slide 10 which is axially slidable within the sleeve 6 , i.e. slidable in the longitudinal direction of the sleeve 6 .", "The slide 10 is substantially cylindrical and is designed having a plurality of different sections with different diameters.", "More specifically, the slide 10 comprises two sections, 11 and 12 , respectively, which have an outer diameter which is somewhat smaller than the inner diameter of the sleeve 6 .", "Between these sections, 11 and 12 , is a section 13 having a substantially smaller diameter, according to FIG. 1 .", "This last-mentioned section 13 is located such that its position corresponds to the location of a detector means 14 , which preferably consists of an inductive position detector.", "The detector 14 is mounted at a hole 15 through the periphery of the sleeve 6 with the help of a detector holder 16 , which is arranged on the sleeve 6 .", "The detector 14 is furthermore connected to a control unit (not shown) for the boat engine by means of an electrical connection 17 .", "This control unit is arranged in a conventional way to regulate the ignition of the engine cylinders.", "As is described in further detail below, the detector is arranged to detect whether the slide 10 is displaced axially, i.e. if the section 13 having a comparatively small diameter is moved to either side so that it no longer is situated directly in front of the detector 14 .", "If this is the case, the detector 14 will generate a signal to the engine control unit, which in turn causes the ignition to be switched off to at least one of the engine cylinders.", "The end of the slide 10 which is facing away from the control means 2 is shaped as a fitting for a wire 18 .", "The outer casing of the wire 18 is not shown in FIG. 1 .", "The end part 19 of the slide 10 is preferably shaped as a hexagonal grip which is protruding from the sleeve 6 and which furthermore comprises an internal, threaded hole 20 .", "In this way, the wire 18 may be fastened in the slide 10 and will then constitute an axial elongation of the slide 10 .", "The wire 18 is connected to the boat's shifting mechanism (not shown), which preferably comprises a transmission of an essentially known type and which has a vertical shaft on which two axially spaced apart, conical cogwheels are arranged, and the vertical shaft in turn is connected to the boat propeller shaft.", "Either of these cogwheels may be engaged with a driving cogwheel on the engine output shaft so that the engine power may be transferred to the propeller shaft.", "The shifting mode, i.e. the direction of rotation of the propeller shaft, is then determined by which one of the two driven cogwheels is engaged.", "If neither of these two cogwheels is engaged, the neutral position is at hand.", "From FIG. 1 it is apparent that the sleeve 6 carries a spring means 21 which runs around the slide 10 .", "The spring means 21 is held in place in a compressed state between a locking ring 22 , which is fastened in a corresponding internal groove 30 in the sleeve 6 , and an end piece 23 which is part of the slide 10 .", "This end piece 23 preferably consists of a cylindrical part having an outer diameter which is somewhat smaller than the inner diameter of the sleeve 6 .", "Furthermore, it is apparent from FIG. 1 that the slide 10 has an outer step 24 which is formed by a reduction of the diameter of the slide 10 .", "When the device is in the state which is shown in FIG. 1, the outer step 24 is situated in substantially the same axial position as the locking ring 22 .", "The sleeve 6 further has an inner step 25 which is formed by an increase of the inner diameter of the sleeve 6 .", "In the state shown in FIG. 1, the inner step 25 is situated in substantially the same axial position as the end piece 23 which is facing the spring means 21 .", "The inner surface of the end piece 23 is shaped so that it is somewhat bevelled at one end.", "In this manner, the end piece 23 may be fastened in the slide 10 by riveting on the end of the slide 10 , whereby the material of the end of the slide 10 will extend and lock the end part 23 against a surface which is defined by a further step 31 on the slide 10 .", "The functioning of the slide will now be described.", "If the control means 2 is not subject to any force in the “F”", "or “R”", "directions, the slide 10 will be situated in the position which is shown in FIG. 1, i.e. the part 13 of the slide 10 which has a relatively small outer diameter will be directly in front of the detector 14 .", "If the control means 2 is actuated in the “F”", "direction, the whole device 1 will primarily be displaced towards the left, during which a substantially rigid connection is present between the sleeve 6 and the slide 10 .", "During shifting, a certain shifting resistance may be felt when manoeuvering the control means 2 , as has been explained above.", "When this resistance exceeds a force which corresponds to the spring force supplied by the spring means 21 , the spring means 21 will start being compressed.", "More exactly, the spring means 21 will then be compressed between the inner step 25 of the sleeve 6 and the outer step 24 of the slide 10 .", "The sleeve 6 will thus be displaced axially relative the slide 10 so that the part 11 will approach a position in front of the detector 14 .", "As mentioned above, the detector suitably comprises an inductive position transducer of a known type.", "This type of transducer comprises an oscillator which emits an electromagnetic field which is affected by the possible presence of electrically conductive objects.", "When the slide 10 (which preferably is made of stainless steel) is displaced so that the part 11 approaches a position directly in front of the detector 14 , the electric field will be disturbed.", "This causes the detector 14 to deliver a signal to the engine control unit, which as mentioned above will cause the ignition to at least one of the engine cylinders to be switched off.", "Correspondingly, the control means 2 may be actuated in the “R”", "direction.", "When a low shifting resistance is present, a substantially rigid connection is present between the sleeve 6 and the slide 10 .", "At the shifting resistance which exceeds the spring force of the spring means 21 , the sleeve 6 will be displaced relative to the slide 10 while the spring means 21 will be compressed between the locking ring 22 and the end piece 23 .", "This will cause the section 12 of the slide 10 to be situated in front of the detector 14 .", "In an analogous manner to what has been explained above, the detector 14 will then deliver a signal to the engine control unit for switching off the ignition to at least one engine cylinder.", "FIG. 2 shows schematically how the invention may be mounted and used in a boat.", "The device 1 for assisted shifting is then connected to a wire 18 which, in turn, has an outer cover 26 which is fastened to special extension housing 27 .", "This extension housing 27 comprises a substantially cylindrical means to which the outer cover 26 is fixedly arranged.", "The extension housing 27 is, in turn, fixedly arranged in construction 5 , which belongs to the control means 2 and which in turn is fixedly arranged in the boat.", "Furthermore, the other end of the wire 18 is connected to a control means in the form of a control lever 28 which, in turn, is pivotably suspended, by means of an axle 29 , and is arranged to actuate a transmission (not shown) connected to the boat's engine.", "This transmission may, for example, be of the type whose functioning has been described above.", "In this way, the transmission may be changed between forwards, reverse, and neutral positions respectively.", "The device 1 according to the present invention may be assembled in the following manner.", "Firstly, the end piece 23 is put in position inside the sleeve 6 , i.e. at the part of the sleeve 6 which is furthest to the right, according to FIG. 1 .", "Thereafter, the spring means 21 is placed in the sleeve 6 , whereafter the locking ring 22 is locked in its inner groove.", "Thereafter, the slide 10 is put in place, and its end part is pressed through the end piece 23 .", "Finally, the end piece 23 is fixedly locked by riveting against the end of the slide 10 , as discussed above.", "The present invention is not limited to the embodiment described above and shown in the drawings, but may be varied within the scope of the appended claims.", "For example, the force which is obtained through the spring means 21 may be varied according to the amount of shifting resistance which is desirable before the slide 10 and the sleeve 6 will be displaced relative to each other.", "The sleeve 6 may furthermore be arranged in direct connection to the control means 2 (by means of the interlocking means 8 ) or be connected to the control means 2 by means of an intervening actuator means, for example a wire of the same type as wire 18 discussed above.", "The present invention may be used for both inboard as well as outboard drives.", "The invention may also be used in connection with shifting mechanisms which utilize a conical clutch, as described above, or alternatively a dog clutch or some other type of transmission.", "Although the term “boat”", "has been used above, the present invention is suitable for use in connection with both smaller pleasure crafts, larger ships and other water vessels where there is a need for assisted shifting of a transmission.", "The invention may, in principle, be used in other contexts than boats.", "The present invention may be used in connection with boats having one, two or more propellers and a corresponding number of propeller shafts.", "Concerning choices of material, the sleeve 6 is preferably made of aluminium or a suitable aluminium alloy.", "The slide 10 is, as mentioned above, preferably made of stainless steel.", "The present invention may be used in such a way that the regulating signal which is initiated by the detector 14 , and which switches off the ignition for at least one engine cylinder, is only valid for a certain limited time.", "This is a safety related advantage which makes it possible for the engine to still operate even if, for example, the detector 14 were to deliver a faulty signal.", "Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention.", "It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims." ]
FIELD OF THE INVENTION This invention relates to nuclear reactors and more particularly, to heterogeneous reactor cores of the seed-blanket type. BACKGROUND OF THE INVENTION A long lifetime nuclear reactor of the type on which the present invention is an improvement is disclosed in U.S. Pat. No. 3,252,867 (Conley). Such heterogenous reactors have been used as power producing reactors in a number of locations and for example, have been constructed using a seed of highly enriched uranium-235 and a blanket of natural uranium. A Light Water Breeder Reactor (LWBR) has been built using a seed of uranium-233 and a blanket of thorium-232. Both of these heterogeneous nuclear systems have utilized seed-blanket constructions wherein the fissile (seed) and fertile (blanket) nuclear fuels are segregated in a radial fashion throughout the core. This construction has resulted in radial core regions of high power density which lie adjacent to radial core regions of low power density, thereby producing relatively high radial power peaking, and hydraulic orificing has been required to balance the thermal performance of the core. The Conley reference mentioned above specifically concerns a seed-blanket reactor wherein a plurality of seed regions are disposed in radially spaced relationship with a blanket region surrounding each of the seed regions. Other patents of possible interest here include U.S. Pat. Nos. 2,992,174 (Edlund et al); 3,211,621 (Creagan); 3,396,078 (Visner); 3,660,227 (Ackroyd et al); 3,671,392 (Beaudoin et al); 3,960,655 (Bohanon); and 4,257,847 (Gibby et al). These patents disclosed various arrangements of the fertile and fissile fuel materials in the fuel element of breeder reactors. For example, the Beaudoin et al patent discloses a light-water breeder reactor including a specific axial arrangement of fertile and fissile fuel materials and the Gibby et al patent discloses a nuclear breeder reactor including a particular arrangement of fertile and fissile fuel material within the reactor core. The Creagan patent discloses a breeder or converter type neutronic reactor including a particular arrangement of fissile and fertile fuel. SUMMARY OF THE INVENTION This invention relates to a nuclear fuel element construction which offers improved nuclear and thermal/hydraulic performance over other, conventional seed-blanket fuel element constructions. A key feature of the invention concerns the provisions of an alternating module construction comprising at least two module types which have different axial stacking arrangements of seed (fissile enriched) and blanket (fertile) fuel pellet regions, such that an axial overlap of seed regions is produced between adjacent modules and such that each blanket region is surrounded as completely as possible by seed regions. The blanket regions of one type of module are axially shorter than the seed regions and, with the arrangement of the invention, axially coincide with seed regions in the other types of modules. This enhances the neutron communication between the different module types, thereby increasing stability insofar as axial and radial power oscillations are concerned. The fuel element construction of the invention takes advantage of the superior conversion characteristics of seed-blanket fuel constructions including increased lifetime, and through the use of an axial arrangement of the seed and blanket regions in the different module types, produces a more even power deposition in the coolant in the radial direction. The latter advantage results from the fact that with axial coolant flow, all coolant flow passes through both seed and blanket regions with this axial seed-blanket arrangement. As mentioned above, conventional reactors of the seed-blanket type employ radial segregation of the fissile and fertile nuclear fuels, which produces radial core regions of high power density and therefore requires special hydraulic orificing to balance the thermal performance of the core. The axially staggered seed-blanket fuel element construction of the invention involves two principles. First, the arrangement of the fissile and fertile regions in an alternating axial manner minimizes the radial power peaking factors and provides a more optimal thermal-hydraulic design. This is particularly important in core constructions in which the coolant flows axially through the power producing regions of the core. Second, arrangement of the axial seed-blanket pattern in a different and staggered manner in each of at least two module types, which modules are, in turn, located in an alternating sense radially throughout the core, provides enhanced stability against power oscillations. As discussed below, calculations have shown that arbitrary axial arrangements of the seed-blanket regions often lead to high axial peaking factors and highly unstable axial power distributions. Other features and advantages of the present invention will be set forth in, or apparent from, the detailed description of the preferred embodiments of the invention found hereinbelow. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of a heterogeneous reactor core illustrating a first pattern of square modules; FIG. 2 is a schematic plan view similar to that of FIG. 1 illustrating a second pattern of square modules; FIG. 3 is a schematic perspective view of a portion of a heterogeneous reactor core employing square modules and illustrating the axially offset or staggered relationship between the blanket and seed regions; FIG. 4 is a plan view similar to FIGS. 1 and 2 illustrating a pattern of hexagonal modules; FIG. 5 is a perspective view similar to FIG. 3 illustrating the relationship between a section of the modules of FIG. 4; FIG. 6 is a schematic representation of the individual fuel rod of the invention; and FIGS. 7 and 8 are graphs showing the axial power shapes exhibited by a core constructed in accordance with the invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1, 2 and 3, two embodiments of a "square" arrangement of type "A" and type "B" modules are illustrated. As seen in FIG. 1, in a first embodiment, the type "A" and type "B" are arranged radially in an alternating manner so that, apart from the modules located at the edges, each side of each "A" module borders on the adjacent side of a "B" module and each side of each "B" module borders on the adjacent side of an "A" module. In the embodiment of FIG. 2, the "A" modules are arranged in a first series of spaced rows which are crossed by a second series of spaced rows orthogonal to the first rows and the "B" modules are disposed in an alternating pattern between the rows of "A" modules so that each of the "B" modules is surrounded on all four sides by "A" modules. It is noted that the locations of the "A" and "B" modules may be interchanged everywhere so as to produce a pattern which is the inverse of those illustrated and thereby provide additional embodiments of the same characteristics, i.e., patterns wherein at least one of the module types "A" or "B" is surrounded on all sides by modules of the other type. Referring to FIG. 3, a perspective view is provided which shows the alternating or staggered axial arrangement of the blanket regions 10 and seed regions 12 as well as the staggered relationship of the modules themselves. Thus, considering the type "A" module denoted 14 as typical, it will be seen that the blanket regions 10 14 alternate with the seed regions 12 14 along the length of module 14. Further, considering one of the next adjacent "B" modules, denoted 16, it will be seen that the alternating blanket regions 10 16 and seed regions 12 16 are staggered in relationship to those of module 14, thus, the seed regions 12 16 of module 16 all lie adjacent to blanket regions 10 14 of module 14 and the seed regions 12 14 of module 14 all lie adjacent to blanket regions 10 16 of module 16. A further embodiment of the inventions is shown in FIGS. 4 and 5 wherein the modules are hexagonal in shape. As illustrated in FIG. 4, the pattern of "A" and "B" modules, as viewed in plan, is such that all of the "A" modules (except those at the edge of the core) are surrounded on all six sides by "B" modules. Further, as shown in FIG. 5, the blanket regions, generally denoted 10', are arranged axially relative to seed regions, generally denoted 12', in the "A" and "B" modules such that the blanket regions 10a' of the "A" modules are staggered axially relative to the blanket regions 10b' of the "B" modules. Thus, as illustrated, the blanket regions 10a' of the "A" modules are surrounded on all sides by seed material, viz, seed material 12a' of its own module in an axial direction and seed material 12b' of adjacent "B" modules in a radial direction. The axial material arrangements of the individual "A" and "B" type fuel rods of the axially staggered seed-blanket core design of the invention are shown in somewhat more detail in FIG. 6, wherein a type "A" module seed rod is shown at 18 and a type "B" seed rod at 20. The seed and blanket regions are denoted 10 and 12 as in FIGS. 1 to 3 and typical values for the lengths of the blanket regions are indicated in FIG. 6. Reflectors 22 are located at each end of the two rods 18 and 20. An evaluation of the fuel element construction of the invention was made using the core design features of an equilibrium cycle light water breeder reactor which uses a 233 UO 2 -ThO 2 based fuel system. An axially staggered seed-blanket fuel construction such as described above was incorporated into this design replacing the standard binary fuel rods. Comparisons of nuclear performance characteristics were made between the construction of the invention and the base construction. The base design utilized for the evaluations is a 1000 MW(e) light water equilibrium cycle breeder concept which fits into a 256-inch ID vessel. This design has an equilibrium cycle fissile inventory ratio (FIR) greater than 1.01, where FIR is defined as the ratio of fissile fuel produced to fissile fuel input for the cycle. The core is capable of daily swing load operation between 50% and 100% of full power using the control rods for reactivity control. One third of the core is refueled each year. Results indicate that by incorporating the axially staggered seed-blanket arrangement of the invention into this design, this core can be batch depleted for approximately four years and will provide a slightly higher equilbrium cycle FIR. The base design utilized for the evaluation consists of 211 hexagonal fuel modules, 42 high power blanket modules of reduced size which are used to flatten the power shapes at the core periphery, and 54 thoria reflector modules adjacent to the core barrel. The 211 hexagonal fuel modules are arranged on a 13-inch hexagonal pitch. The fuel stack height of the base design utilized for the evaluation is 12 feet, consisting of a 10-foot binary (UO 2 -ThO 2 ) pellet stack with 1-foot top and bottom reflector blanket stacks of thoria pellets. Considering the axially staggered seed-blanket fuel design which was incorporated into the base design for comparison purposes, the binary fuel rods (seed rods) are fueled with alternate stack lengths of binary (seed) and thoria (blanket) pellets. Two module types were utilized for the evaluation, with different axial arrangements of the blanket regions to produce an axial overlap of seed regions between the two module types as shown in FIG. 6. As noted above, this arrangement enhances the neutron communication between the two module types and provides increased stability against power oscillations. A diffusion theory 2-D (R-Z) module was used in the analysis of both the axially staggered seed-blanket construction of the invention and the base construction. The model represented three modules (two Type A and one Type B) with a zero-current boundary condition to simulate an infinite array of these three modules. Only the axial geometry descriptions of the binary fuel rods differed between the two cases which were analyzed. Both diffusion theory models were depleted at predetermined eigen-values which were selected to account for leakage effects in a full core batch loaded representation for the axially staggered seed-blanket design model and a three-zone, fuel managed representation for the base design model. Control rod positions were moved throughout life to obtain these predetermined eigen-values. Referring to FIGS. 6, 7 and 8 there are shown, respectively the axial material arrangements in the fuel rods of the Type A and Type B modules (FIG. 6), the axial power shape produced at 0 hours (FIG. 7) and the axial power shape at 26,300 hours (FIG. 8) (4 years at 75% capacity) for an axially staggered seed-blanket core constructed in accordance with a specific embodiment of the invention. It is noted that the thoria layers produce a significant amount of power at 26,300 hours. Comparing the control rod motion of the two constructions with lifetime, it is noted that in the axially staggered seed-blanket construction the control rods are initially withdrawn as xenon, samarium and protactinium buildup to equilibrium levels, are re-inserted slightly between about 5000 hours and about 11000 hours to control an increase in reactivity and finally are withdrawn again after about 11000 hours. Table 1 below is a comparison of the performance characteristics of the two constructions. Both constructions have a 1000 MW(e) power rating but slightly different NW(th) ratings. The axially staggered seed-blanket construction achieves 33.6% higher burnup than the base construction at the expense of 11.0% lower kw(th)/kg-fissile specific power. The FIR for the initial cycle for the axially staggered seed-blanket construction is estimated to be 1.029 and for the equilibrium cycle 1.012. These values are slightly higher than the corresponding FIR's of 1.028 and 1.011 calculated for the base design for its cycle lifetime. It is noted that the axially staggered seed-blanket construction offers a 4-year batch loaded operation of the core as compared to annual partial refuelings for the base construction. The axially staggered seed-blanket construction requires a 5.4% higher total fissile loading commitment for incore and excore inventories, but offers 13.2% greater potential energy extraction form heavy metal resource. TABLE 1______________________________________Performance Characteristics of Evaluated Constructions Axially Staggered Base Seed-BlanketParameters Construction Construction______________________________________Core Power, MW(e) 1000 1000MW(th) 2992 2994Module Power density,kW (th)/kg-fissile 607 540kW (th)/liter 47.0 47.0FIR - initial cycle 1.028 1.029equilibrium cycle 1.011 1.012Burnup, MWD/MT 7332 9794Energy potential, GWD/MT 403 456Peak thermal output of fuel 12.6 13.3rods kw/ftLifetime, yr. module 3 4Refueling cycle, yr. 1 4______________________________________ Peak linear power density values were calculated using the results obtained from the module calculations and applying hot module and physics uncertainty factors as well as accounting for gamma heating effects. For the axially staggered seed-blanket construction originally analyzed, the peak linear power density obtained for the binary seed rods was 15.1 kw/ft compared to a limit of 14 kw/ft. The following actions were taken to produce an acceptable linear power in the binary fuel rods. An adjustment of the relative fissile loadings in the Type A and Type B modules was made to reduce the power in the module type with the limiting binary seed rod by approximately 6%. This reduced the peak linear power in the binary rods to 14.4 kw/ft. The total binary fuel length in the seed rods was then increased by approximately 3% by reducing the thoria layer thicknesses to achieve a further reduction in binary rod peak linear power to a value under 14 kw/ft. Calculations to confirm that these changes result in acceptable binary rod linear power (14 kw/ft) were performed and a peak binary linear power of 13.3 kw/ft was obtained. For the base construction, the peak linear power density obtained for the binary seed rods was 12.6 kw/ft which is below the 14 kw/ft limit. Further optimization of the particular axially staggered axial seed-blanket concept that was evaluated might produce additional improvements. An initial study of a concept with thinner blanket layers produced a design with a 2.3-year batch core lifetime. The use of thicker blanket layers could possibly increase the core lifetime at the expense of increasing the fissile loading. However, the use of thicker blanket layers would reduce the axial overlap of seed regions between the two module types, tending to decrease core stability. It will be understood that the fuel element construction of this invention can be used with several types of fuel and control systems. More particularly, in addition to the uranium-thorium oxide fuel system which was analyzed, several other fuel systems could also be employed. A UO 2 fuel system consisting of enriched 235 UO 2 seed regions and natural uranium blanket regions would offer improved fuel utilization relative to conventional fuel systems in once-through fuel applications. This fuel system could eventually be converted to a PuO 2 -UO 2 system with natural uranium blanket regions which would further reduce the requirements of enriched UO 2 . Another possible fuel system would consist of enriched 235 UO 2 seed regions and ThO 2 blanket regions. The uranium-233 produced in the thoria blanket layers could be used in a light water breeder reactor concept consisting of 233 UO 2 -ThO 2 based fuel. Other combinations of nuclear fissile and fertile fuels could offer potential improvements in fuel utilization with the use of the fuel element construction of the invention. It is noted that the fuel element construction of the invention can be used with any combination of fissile and fertile materials. The seed regions can be composed of uranium-233, uranium-235, plutonium-239 or plutonium-241 or a combination of these. The seed fissile material can be in combination with a fertile diluent such as thorium, natural uranium or depleted uranium or a combination of these. The seed fissile material may also be in combination with a non-fertile diluent such as zirconium. Other diluent combinations are, of course, possible. The blanket fertile material can be composed of thorium, natural uranium or depleted uranium or a combination of these. Both seed and blanket materials may be utilized in metallic or non-metallic (e.g., oxide or nitride) form. Either a poison control system (Boron, AG-CD-In, etc. control rods or solution poison) or a movable fuel control system (fissile or fertile) could be used with the fuel element construction of the invention. The choice of reactivity control system would influence the resulting increase in fuel utilization. As discussed above, the fuel element construction of the invention can be used in both square and hexagonal fuel module arrays. In square arrays with two module types, the same number of modules of each of the two module types can be used (see FIG. 1) or there can be three times as many modules of one type as there are of a second type (See FIG. 2). In hexagonal arrays with two module types, there are two modules of one type for every module of the second type (See FIGS. 4 and 5). In hexagonal arrays with three module types (not illustrated) there would be an equal number of modules of each type. Although the invention has been described in detail with respect to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that variations and modifications may be effected in these embodiments within the scope and spirit of the invention.
A heterogeneous nuclear reactor of the seed-blanket type is provided wher the fissile (seed) and fertile (blanket) nuclear fuels are segregated axially within each fuel element such that fissile and fertile regions occur in an alternating pattern along the length of the fuel element. Further, different axial stacking patterns are used for the fuel elements of at least two module types such that when modules of different types are positioned adjacent to one another, the fertile regions of the modules are offset or staggered. Thus, when a module of one type is surrounded by modules of the second type the fertile regions thereof will be surrounded on all sides by fissile material. This provides enhanced neutron communication both radially and axially, thereby resulting in greater power oscillation stability than other axial arrangements. The arrangements of the fissile and fertile regions in an alternating axial manner minimizes the radial power peaking factors and provides a more optional thermal-hydraulic design than is afforded by radial arrangements.
Provide a concise summary of the essential information conveyed in the context.
[ "FIELD OF THE INVENTION This invention relates to nuclear reactors and more particularly, to heterogeneous reactor cores of the seed-blanket type.", "BACKGROUND OF THE INVENTION A long lifetime nuclear reactor of the type on which the present invention is an improvement is disclosed in U.S. Pat. No. 3,252,867 (Conley).", "Such heterogenous reactors have been used as power producing reactors in a number of locations and for example, have been constructed using a seed of highly enriched uranium-235 and a blanket of natural uranium.", "A Light Water Breeder Reactor (LWBR) has been built using a seed of uranium-233 and a blanket of thorium-232.", "Both of these heterogeneous nuclear systems have utilized seed-blanket constructions wherein the fissile (seed) and fertile (blanket) nuclear fuels are segregated in a radial fashion throughout the core.", "This construction has resulted in radial core regions of high power density which lie adjacent to radial core regions of low power density, thereby producing relatively high radial power peaking, and hydraulic orificing has been required to balance the thermal performance of the core.", "The Conley reference mentioned above specifically concerns a seed-blanket reactor wherein a plurality of seed regions are disposed in radially spaced relationship with a blanket region surrounding each of the seed regions.", "Other patents of possible interest here include U.S. Pat. Nos. 2,992,174 (Edlund et al);", "3,211,621 (Creagan);", "3,396,078 (Visner);", "3,660,227 (Ackroyd et al);", "3,671,392 (Beaudoin et al);", "3,960,655 (Bohanon);", "and 4,257,847 (Gibby et al).", "These patents disclosed various arrangements of the fertile and fissile fuel materials in the fuel element of breeder reactors.", "For example, the Beaudoin et al patent discloses a light-water breeder reactor including a specific axial arrangement of fertile and fissile fuel materials and the Gibby et al patent discloses a nuclear breeder reactor including a particular arrangement of fertile and fissile fuel material within the reactor core.", "The Creagan patent discloses a breeder or converter type neutronic reactor including a particular arrangement of fissile and fertile fuel.", "SUMMARY OF THE INVENTION This invention relates to a nuclear fuel element construction which offers improved nuclear and thermal/hydraulic performance over other, conventional seed-blanket fuel element constructions.", "A key feature of the invention concerns the provisions of an alternating module construction comprising at least two module types which have different axial stacking arrangements of seed (fissile enriched) and blanket (fertile) fuel pellet regions, such that an axial overlap of seed regions is produced between adjacent modules and such that each blanket region is surrounded as completely as possible by seed regions.", "The blanket regions of one type of module are axially shorter than the seed regions and, with the arrangement of the invention, axially coincide with seed regions in the other types of modules.", "This enhances the neutron communication between the different module types, thereby increasing stability insofar as axial and radial power oscillations are concerned.", "The fuel element construction of the invention takes advantage of the superior conversion characteristics of seed-blanket fuel constructions including increased lifetime, and through the use of an axial arrangement of the seed and blanket regions in the different module types, produces a more even power deposition in the coolant in the radial direction.", "The latter advantage results from the fact that with axial coolant flow, all coolant flow passes through both seed and blanket regions with this axial seed-blanket arrangement.", "As mentioned above, conventional reactors of the seed-blanket type employ radial segregation of the fissile and fertile nuclear fuels, which produces radial core regions of high power density and therefore requires special hydraulic orificing to balance the thermal performance of the core.", "The axially staggered seed-blanket fuel element construction of the invention involves two principles.", "First, the arrangement of the fissile and fertile regions in an alternating axial manner minimizes the radial power peaking factors and provides a more optimal thermal-hydraulic design.", "This is particularly important in core constructions in which the coolant flows axially through the power producing regions of the core.", "Second, arrangement of the axial seed-blanket pattern in a different and staggered manner in each of at least two module types, which modules are, in turn, located in an alternating sense radially throughout the core, provides enhanced stability against power oscillations.", "As discussed below, calculations have shown that arbitrary axial arrangements of the seed-blanket regions often lead to high axial peaking factors and highly unstable axial power distributions.", "Other features and advantages of the present invention will be set forth in, or apparent from, the detailed description of the preferred embodiments of the invention found hereinbelow.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of a heterogeneous reactor core illustrating a first pattern of square modules;", "FIG. 2 is a schematic plan view similar to that of FIG. 1 illustrating a second pattern of square modules;", "FIG. 3 is a schematic perspective view of a portion of a heterogeneous reactor core employing square modules and illustrating the axially offset or staggered relationship between the blanket and seed regions;", "FIG. 4 is a plan view similar to FIGS. 1 and 2 illustrating a pattern of hexagonal modules;", "FIG. 5 is a perspective view similar to FIG. 3 illustrating the relationship between a section of the modules of FIG. 4;", "FIG. 6 is a schematic representation of the individual fuel rod of the invention;", "and FIGS. 7 and 8 are graphs showing the axial power shapes exhibited by a core constructed in accordance with the invention.", "DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1, 2 and 3, two embodiments of a "square"", "arrangement of type "A"", "and type "B"", "modules are illustrated.", "As seen in FIG. 1, in a first embodiment, the type "A"", "and type "B"", "are arranged radially in an alternating manner so that, apart from the modules located at the edges, each side of each "A"", "module borders on the adjacent side of a "B"", "module and each side of each "B"", "module borders on the adjacent side of an "A"", "module.", "In the embodiment of FIG. 2, the "A"", "modules are arranged in a first series of spaced rows which are crossed by a second series of spaced rows orthogonal to the first rows and the "B"", "modules are disposed in an alternating pattern between the rows of "A"", "modules so that each of the "B"", "modules is surrounded on all four sides by "A"", "modules.", "It is noted that the locations of the "A"", "and "B"", "modules may be interchanged everywhere so as to produce a pattern which is the inverse of those illustrated and thereby provide additional embodiments of the same characteristics, i.e., patterns wherein at least one of the module types "A"", "or "B"", "is surrounded on all sides by modules of the other type.", "Referring to FIG. 3, a perspective view is provided which shows the alternating or staggered axial arrangement of the blanket regions 10 and seed regions 12 as well as the staggered relationship of the modules themselves.", "Thus, considering the type "A"", "module denoted 14 as typical, it will be seen that the blanket regions 10 14 alternate with the seed regions 12 14 along the length of module 14.", "Further, considering one of the next adjacent "B"", "modules, denoted 16, it will be seen that the alternating blanket regions 10 16 and seed regions 12 16 are staggered in relationship to those of module 14, thus, the seed regions 12 16 of module 16 all lie adjacent to blanket regions 10 14 of module 14 and the seed regions 12 14 of module 14 all lie adjacent to blanket regions 10 16 of module 16.", "A further embodiment of the inventions is shown in FIGS. 4 and 5 wherein the modules are hexagonal in shape.", "As illustrated in FIG. 4, the pattern of "A"", "and "B"", "modules, as viewed in plan, is such that all of the "A"", "modules (except those at the edge of the core) are surrounded on all six sides by "B"", "modules.", "Further, as shown in FIG. 5, the blanket regions, generally denoted 10', are arranged axially relative to seed regions, generally denoted 12', in the "A"", "and "B"", "modules such that the blanket regions 10a'", "of the "A"", "modules are staggered axially relative to the blanket regions 10b'", "of the "B"", "modules.", "Thus, as illustrated, the blanket regions 10a'", "of the "A"", "modules are surrounded on all sides by seed material, viz, seed material 12a'", "of its own module in an axial direction and seed material 12b'", "of adjacent "B"", "modules in a radial direction.", "The axial material arrangements of the individual "A"", "and "B"", "type fuel rods of the axially staggered seed-blanket core design of the invention are shown in somewhat more detail in FIG. 6, wherein a type "A"", "module seed rod is shown at 18 and a type "B"", "seed rod at 20.", "The seed and blanket regions are denoted 10 and 12 as in FIGS. 1 to 3 and typical values for the lengths of the blanket regions are indicated in FIG. 6. Reflectors 22 are located at each end of the two rods 18 and 20.", "An evaluation of the fuel element construction of the invention was made using the core design features of an equilibrium cycle light water breeder reactor which uses a 233 UO 2 -ThO 2 based fuel system.", "An axially staggered seed-blanket fuel construction such as described above was incorporated into this design replacing the standard binary fuel rods.", "Comparisons of nuclear performance characteristics were made between the construction of the invention and the base construction.", "The base design utilized for the evaluations is a 1000 MW(e) light water equilibrium cycle breeder concept which fits into a 256-inch ID vessel.", "This design has an equilibrium cycle fissile inventory ratio (FIR) greater than 1.01, where FIR is defined as the ratio of fissile fuel produced to fissile fuel input for the cycle.", "The core is capable of daily swing load operation between 50% and 100% of full power using the control rods for reactivity control.", "One third of the core is refueled each year.", "Results indicate that by incorporating the axially staggered seed-blanket arrangement of the invention into this design, this core can be batch depleted for approximately four years and will provide a slightly higher equilbrium cycle FIR.", "The base design utilized for the evaluation consists of 211 hexagonal fuel modules, 42 high power blanket modules of reduced size which are used to flatten the power shapes at the core periphery, and 54 thoria reflector modules adjacent to the core barrel.", "The 211 hexagonal fuel modules are arranged on a 13-inch hexagonal pitch.", "The fuel stack height of the base design utilized for the evaluation is 12 feet, consisting of a 10-foot binary (UO 2 -ThO 2 ) pellet stack with 1-foot top and bottom reflector blanket stacks of thoria pellets.", "Considering the axially staggered seed-blanket fuel design which was incorporated into the base design for comparison purposes, the binary fuel rods (seed rods) are fueled with alternate stack lengths of binary (seed) and thoria (blanket) pellets.", "Two module types were utilized for the evaluation, with different axial arrangements of the blanket regions to produce an axial overlap of seed regions between the two module types as shown in FIG. 6. As noted above, this arrangement enhances the neutron communication between the two module types and provides increased stability against power oscillations.", "A diffusion theory 2-D (R-Z) module was used in the analysis of both the axially staggered seed-blanket construction of the invention and the base construction.", "The model represented three modules (two Type A and one Type B) with a zero-current boundary condition to simulate an infinite array of these three modules.", "Only the axial geometry descriptions of the binary fuel rods differed between the two cases which were analyzed.", "Both diffusion theory models were depleted at predetermined eigen-values which were selected to account for leakage effects in a full core batch loaded representation for the axially staggered seed-blanket design model and a three-zone, fuel managed representation for the base design model.", "Control rod positions were moved throughout life to obtain these predetermined eigen-values.", "Referring to FIGS. 6, 7 and 8 there are shown, respectively the axial material arrangements in the fuel rods of the Type A and Type B modules (FIG.", "6), the axial power shape produced at 0 hours (FIG.", "7) and the axial power shape at 26,300 hours (FIG.", "8) (4 years at 75% capacity) for an axially staggered seed-blanket core constructed in accordance with a specific embodiment of the invention.", "It is noted that the thoria layers produce a significant amount of power at 26,300 hours.", "Comparing the control rod motion of the two constructions with lifetime, it is noted that in the axially staggered seed-blanket construction the control rods are initially withdrawn as xenon, samarium and protactinium buildup to equilibrium levels, are re-inserted slightly between about 5000 hours and about 11000 hours to control an increase in reactivity and finally are withdrawn again after about 11000 hours.", "Table 1 below is a comparison of the performance characteristics of the two constructions.", "Both constructions have a 1000 MW(e) power rating but slightly different NW(th) ratings.", "The axially staggered seed-blanket construction achieves 33.6% higher burnup than the base construction at the expense of 11.0% lower kw(th)/kg-fissile specific power.", "The FIR for the initial cycle for the axially staggered seed-blanket construction is estimated to be 1.029 and for the equilibrium cycle 1.012.", "These values are slightly higher than the corresponding FIR's of 1.028 and 1.011 calculated for the base design for its cycle lifetime.", "It is noted that the axially staggered seed-blanket construction offers a 4-year batch loaded operation of the core as compared to annual partial refuelings for the base construction.", "The axially staggered seed-blanket construction requires a 5.4% higher total fissile loading commitment for incore and excore inventories, but offers 13.2% greater potential energy extraction form heavy metal resource.", "TABLE 1______________________________________Performance Characteristics of Evaluated Constructions Axially Staggered Base Seed-BlanketParameters Construction Construction______________________________________Core Power, MW(e) 1000 1000MW(th) 2992 2994Module Power density,kW (th)/kg-fissile 607 540kW (th)/liter 47.0 47.0FIR - initial cycle 1.028 1.029equilibrium cycle 1.011 1.012Burnup, MWD/MT 7332 9794Energy potential, GWD/MT 403 456Peak thermal output of fuel 12.6 13.3rods kw/ftLifetime, yr.", "module 3 4Refueling cycle, yr.", "1 4______________________________________ Peak linear power density values were calculated using the results obtained from the module calculations and applying hot module and physics uncertainty factors as well as accounting for gamma heating effects.", "For the axially staggered seed-blanket construction originally analyzed, the peak linear power density obtained for the binary seed rods was 15.1 kw/ft compared to a limit of 14 kw/ft.", "The following actions were taken to produce an acceptable linear power in the binary fuel rods.", "An adjustment of the relative fissile loadings in the Type A and Type B modules was made to reduce the power in the module type with the limiting binary seed rod by approximately 6%.", "This reduced the peak linear power in the binary rods to 14.4 kw/ft.", "The total binary fuel length in the seed rods was then increased by approximately 3% by reducing the thoria layer thicknesses to achieve a further reduction in binary rod peak linear power to a value under 14 kw/ft.", "Calculations to confirm that these changes result in acceptable binary rod linear power (14 kw/ft) were performed and a peak binary linear power of 13.3 kw/ft was obtained.", "For the base construction, the peak linear power density obtained for the binary seed rods was 12.6 kw/ft which is below the 14 kw/ft limit.", "Further optimization of the particular axially staggered axial seed-blanket concept that was evaluated might produce additional improvements.", "An initial study of a concept with thinner blanket layers produced a design with a 2.3-year batch core lifetime.", "The use of thicker blanket layers could possibly increase the core lifetime at the expense of increasing the fissile loading.", "However, the use of thicker blanket layers would reduce the axial overlap of seed regions between the two module types, tending to decrease core stability.", "It will be understood that the fuel element construction of this invention can be used with several types of fuel and control systems.", "More particularly, in addition to the uranium-thorium oxide fuel system which was analyzed, several other fuel systems could also be employed.", "A UO 2 fuel system consisting of enriched 235 UO 2 seed regions and natural uranium blanket regions would offer improved fuel utilization relative to conventional fuel systems in once-through fuel applications.", "This fuel system could eventually be converted to a PuO 2 -UO 2 system with natural uranium blanket regions which would further reduce the requirements of enriched UO 2 .", "Another possible fuel system would consist of enriched 235 UO 2 seed regions and ThO 2 blanket regions.", "The uranium-233 produced in the thoria blanket layers could be used in a light water breeder reactor concept consisting of 233 UO 2 -ThO 2 based fuel.", "Other combinations of nuclear fissile and fertile fuels could offer potential improvements in fuel utilization with the use of the fuel element construction of the invention.", "It is noted that the fuel element construction of the invention can be used with any combination of fissile and fertile materials.", "The seed regions can be composed of uranium-233, uranium-235, plutonium-239 or plutonium-241 or a combination of these.", "The seed fissile material can be in combination with a fertile diluent such as thorium, natural uranium or depleted uranium or a combination of these.", "The seed fissile material may also be in combination with a non-fertile diluent such as zirconium.", "Other diluent combinations are, of course, possible.", "The blanket fertile material can be composed of thorium, natural uranium or depleted uranium or a combination of these.", "Both seed and blanket materials may be utilized in metallic or non-metallic (e.g., oxide or nitride) form.", "Either a poison control system (Boron, AG-CD-In, etc.", "control rods or solution poison) or a movable fuel control system (fissile or fertile) could be used with the fuel element construction of the invention.", "The choice of reactivity control system would influence the resulting increase in fuel utilization.", "As discussed above, the fuel element construction of the invention can be used in both square and hexagonal fuel module arrays.", "In square arrays with two module types, the same number of modules of each of the two module types can be used (see FIG. 1) or there can be three times as many modules of one type as there are of a second type (See FIG. 2).", "In hexagonal arrays with two module types, there are two modules of one type for every module of the second type (See FIGS. 4 and 5).", "In hexagonal arrays with three module types (not illustrated) there would be an equal number of modules of each type.", "Although the invention has been described in detail with respect to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that variations and modifications may be effected in these embodiments within the scope and spirit of the invention." ]
[0001] This application claims priority of Provisional Application Ser. No. 61/201,865 filed Dec. 16, 2008, the disclosure of which is hereby incorporated by reference. FIELD OF THE INVENTION [0002] The present invention relates to stirred tank containers, and related methods. BACKGROUND OF THE INVENTION [0003] The general process for the manufacture of biomolecules, such as proteins, particularly recombinant proteins, typically involves two main steps: (1) the expression of the protein in a host cell, followed by (2) the purification of the protein. The first step involves growing the desired host cell in a bioreactor to effect the expression of the protein. Some examples of cell lines used for this purpose include Chinese hamster ovary (CHO) cells, myeloma (NSO) bacterial cells such as e-coli and insect cells. Once the protein is expressed at the desired levels, the protein is removed from the host cell and harvested. Suspended particulates, such as cells, cell fragments, lipids and other insoluble matter are typically removed from the protein-containing fluid by filtration or centrifugation, resulting in a clarified fluid containing the protein of interest in solution as well as other soluble impurities. [0004] The second step involves the purification of the harvested protein to remove impurities which are inherent to the process. Examples of impurities include host cell proteins (HCP, proteins other than the desired or targeted protein), nucleic acids, endotoxins, viruses, protein variants and protein aggregates. This purification typically involves several chromatography steps, which can include affinity chromatography, ion exchange, hydrophobic interaction, etc. on solid matrices such as porous agarose, polymeric or glass or by membrane based adsorbers. [0005] One example of a chromatography process train for the purification of proteins involves protein-A affinity, followed by cation exchange, followed by anion exchange. The protein-A column captures the protein of interest or target protein by an affinity mechanism while the bulk of the impurities pass through the column to be discarded. The protein then is recovered by elution from the column. Since most of the proteins of interest have isoelectric points (PI) in the basic range (8-9) and therefore being positively charged under normal processing conditions (pH below the PI of the protein), they are bound to the cation exchange resin in the second column. Other positively charged impurities are also bound to this resin. The protein of interest is then recovered by elution from this column under conditions (pH, salt concentration) in which the protein elutes while the impurities remain bound to the resin. The anion exchange column is typically operated in a flow through mode, such that any negatively charged impurities are bound to the resin while the positively charged protein of interest is recovered in the flow through stream. This process results in a highly purified and concentrated protein solution. [0006] Other alternative methods for purifying proteins have been investigated in recent years. One such method involves a flocculation technique. In this technique, a soluble polyelectrolyte is added to an unclarified cell culture broth to capture the suspended particulates and a portion of the soluble impurities thereby forming a flocculant, which is subsequently removed from the protein solution by filtration or centrifugation. [0007] Alternatively, a soluble polyelectrolyte is added to clarified cell culture broth to capture the biomolecules of interest, thereby forming a flocculant, which is allowed to settle and can be subsequently isolated from the rest of the solution. The flocculant is typically washed to remove loosely adhering impurities. Afterwards, an increase in the solution's ionic strength brings about the dissociation of the target protein from the polyelectrolyte, subsequently resulting in the resolubilization of the polyelectrolyte into the protein-containing solution. [0008] In co-pending application U.S. Ser. No. 12/004,314 filed Dec. 20, 2007, the disclosure of which is hereby incorporated by reference, a polymer, soluble under certain conditions, such as temperature, pH, salt, light or combinations thereof, is used to bind impurities while in its soluble state and is then precipitated out upon a change in condition (pH or temperature, etc.) removing the impurities with it. The biomolecule of interest is then further treated using traditional chromatography or membrane adsorbers and the like. [0009] All of the protein purification technologies discussed above share a common theme, namely, to first remove suspended particulates in a first distinct step and then in a second step separate the biomolecules of interest from soluble impurities which are inherent to the process. [0010] In situ product recovery with derivatized magnetic particles is one example of a protein purification technique where the biomolecules of interest can be purified directly from an un-clarified cell culture broth. In this technique, a polymer shell encapsulating a magnetic bead is functionalized with an affinity ligand that seeks out and binds the target protein. A magnetic field is then applied to collect the bead-protein complexes, leaving behind the soluble impurities and insoluble particulates. [0011] The main drawback of this technique is that it requires appreciable capital investments in design, construction and validation of high-gradient magnetic separators. Also, the technique does not lend itself to disposable applications, which are poised to become the norm for protein purification in the Bioprocess industry. [0012] In co-pending application filed Dec. 16, 2008 under Attorney Docket No. MCA-1046, entitled “Purification of Proteins” by Moya, Wilson, et al., the disclosure of which is hereby incorporated by reference, there is disclosed a polymer such as a soluble polymer capable of substantially irreversibly binding to insoluble particulates and a subset of soluble impurities and also capable of reversibly binding to one or more desired biomolecules in an unclarified biological material containing stream and the methods of using such a material to purify one or more desired biomolecules from such a stream without the need for prior clarification. More specifically, this co-pending application discloses a stimuli responsive polymer such as a selectively soluble polymer capable of selectively and reversibly binding to one or more desired biomolecules in an unclarified biological material containing stream and the methods of using such a polymer to purify one or more desired biomolecules from such a complex mixture of materials including the biomolecule(s) of interest and various impurities such as other proteins (host cell proteins), DNA, virus, whole cells, cellular debris and the like without the need for prior clarification of the stream. [0013] The polymer is soluble under a certain set of process conditions such as one or more of pH, salt concentration, temperature, light, or electrical field, and is able to interact and complex with insoluble impurities (cells, debris, etc.) and a fraction of the soluble impurities, and is rendered insoluble and precipitates out of solution upon a change in conditions (temperature, salt concentration, light, electrical field, or pH), e.g. a stimuli responsive polymer. Only when precipitated out of solution, the polymer is capable of reversibly binding to one or more desired biomolecules within the stream (protein, polypeptide, etc.) in an unclarified cell broth. The precipitate can then be removed from the stream, such as by being filtered out from the remainder of the stream and the desired biomolecule is recovered such as by selective elution from the precipitate. [0014] The removal of the precipitate, however, can be problematic, as it is typically in the form a large mass of sludge. [0015] It would be desirable to provide an apparatus and method for the efficient purification of samples, particularly those containing biomolecules, preferably within a single, integral, apparatus that reduces or eliminates one or more process steps that can result in contamination or material loss. SUMMARY OF THE INVENTION [0016] The problems of the prior art have been overcome by the embodiments disclosed herein, which include a container or housing for sample preparation or processing, such as biomass culturing or processing, and optionally sample purification. In certain embodiments, the container or housing is a mixer. In certain embodiments, the container or housing is a reactor. In certain embodiments, the reactor is a bioreactor, which can be disposable or reusable, that includes a stirred cell device that can simulate a tangential flow filter to reduce or eliminate clogging that can be caused by the solids generated. In certain embodiments, the solids comprise a precipitate or floc, such as one that includes a polymer that binds the biomolecule(s) of interest, and impurities such as cells and cell components. In certain embodiments, the stirred cell component includes one or more membranes for purification, such as during recovery (e.g., by elution) of the biomolecule(s) of interest. In certain embodiments, the biomolecules are proteins, polypeptides or antibodies. In certain embodiments, the container has two compartments. In certain embodiments the container has two compartments each of which has a membrane with it. In certain embodiments, the container has two compartments, the first having a membrane, the second being in fluid communication with a filter device downstream of the second compartment outlet. [0017] In its method aspects, embodiments disclosed herein include purification and isolation of biomolecules of interest derived from cell culture fluids. In certain embodiments, the methods include carrying out sample preparation or processing in a container or housing, such as culturing a biomass; generating solids such as by precipitating or flocculating a biomolecule of interest from the cultured broth; preventing the solids from settling in the container by agitation; and purification, such as by binding and eluting the biomolecule of interest and filtering the same. In certain embodiments, the sample processing involves expressing a protein of interest. In certain embodiments, the solids comprise a precipitate that includes a polymer bound to the protein of interest, and the purification involves binding and elution and one or more filtration steps. In certain embodiments, the solids comprise a precipitate that includes a polyelectrolyte bound to the protein of interest, and the purification involves binding and elution and one or more filtration steps. In certain embodiments, the polymer is bound to the impurities (cells, cell debris, etc.) and the biomolecule remains in the supernatant. The precipitation step may replace conventional chromatographic separations, may be used as a direct capture step to isolate the protein of interest from the cell culture broth, or may simply be an intermediate purification step. In certain embodiments, affinity or ion exchange beads or beads having any ligand or functionality capable of purifying the biomolecule may be used instead of a polymer to bind a biomolecule of interest. In certain embodiments, the one or more filtration steps are carried out in situ in the same apparatus as the sample processing. In certain embodiments, the eluted protein is subjected to further purification, such as by affinity and/or ion exchange chromatography. BRIEF DESCRIPTION OF THE DRAWINGS [0018] FIG. 1 is a perspective view of a bioreactor in accordance with certain embodiments; [0019] FIG. 2 is a cross-sectional view of a portion of the bioreactor of FIG. 1 ; [0020] FIG. 3 is a perspective view of a bioreactor base in accordance with certain embodiments; [0021] FIG. 4 is a perspective view of the base of FIG. 3 , including a membrane sealed thereon; [0022] FIG. 5 is a perspective view of a bioreactor assembly, including a housing, a bioreactor base, and a filtration base; [0023] FIG. 6 is a perspective view of a filtration base in accordance with certain embodiments; and [0024] FIG. 7 is a perspective view of an agitator in accordance with certain embodiments. DETAILED DESCRIPTION [0025] Suitable containers or housings useful here in useful herein are not particularly limited. For purposes of illustration, reactors, and in particular, bioreactors, will be discussed in detail, which include disposable as well as reusable bioreactors. For example, solvent-resistance bioreactors having a borosilicate glass cylinder and PTFE components, such as those commercially available from Millipore Corporation, can be used. Similarly, disposable bioreactors that utilize bags, or that are formed of semi-rigid or rigid molded plastic, can be used. Such disposable bioreactors are generally pre-sterilized. Means for agitation within the bioreactor is also not particularly limited, and includes impeller-based agitation, magnetic stirrers, as well as wave-induced agitation and agitation induced by gas bubbles. Agitation is important in preventing solids from settling and plugging the one or more membranes used for purification. [0026] The following description is in reference to a bioreactor. Those skilled in the art will appreciate that it is for illustrative purposes only, and that the embodiments disclosed herein are applicable to any container containing a liquid sample having, or ultimately forming, a sample having a relatively high solids content. [0027] Turning now to FIGS. 1 and 2 , bioreactor 2 is shown held in a stand 4 , which is comprised of several legs 6 (in this embodiment 3 legs although one continuous leg or 2 large legs or more than 3 legs can also be used) and a support rim 8 . As shown the legs 6 may have an optional support piece 10 at or near the bottom to keep the legs 6 from spreading when the bioreactor 2 is filled and in the stand 4 . [0028] Depending upon the type of circulation or agitation system used, the stand 4 may also support the drive mechanism 12 (as shown) for the circulation mechanism, which typically is a stirrer or paddle assembly 14 . In this particular embodiment, the drive mechanism 12 is a motor and is mounted to the top of the centered above the top 16 of the bioreactor 2 by several arms 18 (although 3 are shown alternative numbers may be used). Other features such as mounting blocks (not shown) and the like may be formed on the top 16 or support rim 8 to support the drive mechanism 12 . As shown, the drive mechanism 12 has a shaft 20 that can be attached to the stirrer as explained later herein. Other stands can be used in lieu of the design described above and will work equally well. [0029] The bioreactor body 22 (only partially shown in FIG. 1 ) has an interior space into which the fluids, cells, probes and other devices of the bioreactor are at least partially contained. The body 22 is sealably attached to the top 16 . This may be by a mechanical seal such as a rubber gasket and clips 24 (as shown) or by a clamp, such as a band clamp or Ladish or TriClover clamp, mated threads on the top 16 and body 22 and the like. Alternatively, they may be sealed by adhesives or heat sealing of the top 16 to the body 22 or formed together in one piece such as in a rotomolding apparatus. [0030] The body 22 has one or more sidewalls 26 that extend downwardly from the top 16 . As shown, there is one sidewall 26 of a circular or cylindrical design. Alternatively, there can be 3, 4, or more sidewalls if desired (not shown). [0031] Preferably, the body 22 is made of a single piece of molded plastic or glass. Alternatively it may be made of two or more pieces of plastic or glass that are sealed together such as by heat, glue, or gaskets (not shown). Suitable polymers which can be used to form the top and body include but are not limited to polycarbonates, polyesters, nylons, PTFE resins and other fluoropolymers, acrylic and methacrylic resins and copolymers, polysulphones, polyethersulphones, polyarylsulphones, polystyrenes, polyetherimides, nylons, polyesters, polyethylene terephthalates (PET), polyvinyl chlorides, chlorinated polyvinyl chlorides, ABS and its alloys and blends, polyolefins, preferably polyethylenes such as linear low density polyethylene, low density polyethylene, high density polyethylene, and ultrahigh molecular weight polyethylene and copolymers thereof, polypropylene and copolymers thereof and metallocene generated polyolefins. Preferred polymers are polyolefins, in particular polyethylenes and their copolymers; polystyrenes; and polycarbonates. The top and body may be made of the same polymer or different polymers as desired. In reusable embodiments, the body can be made of glass, acrylic, or other materials not deleterious to the process. The body 22 also can be a disposable plastic bag, as is known in the art. [0032] Also formed in the bioreactor 2 of this embodiment are one or more ports 30 (in this embodiment there are three types 30 a - c (for a total of 5 ports) formed in the top 16 and one or more ports 32 in the body 22 (in this embodiment there are at least two different types 32 a - b for a total of seven ports overall). The top 16 and body 22 may have multiple ports of similar and/or of different styles to provide one with the number of ports, of the desired type, in the desired locations throughout the bioreactor 2 . These ports 30 , 32 or at least a portion of them are formed as part of the top 16 and/or body 22 . They may be formed with threads that mate to sealable covers such as closed caps, gasketed caps with a throughbore within the gasket, or various Luer fittings. Alternatively, one or more of the ports can be made in the plastic top 16 and/or body 22 by drilling or burning a hole and then mounting (such as by heat bonding or adhesives) a port in place through or around the hole. Many different port styles and sizes can be accommodated. [0033] Ports 30 a may be used for liquid or gas entrance or exit or for probes such as pH probes, thermometers or thermocouples or the like. Ports 30 b may be used for similar purposes. Port 30 c is for the stirrer shaft described in further detail herein. Alternatively, if the bioreactor is an airlift design and doesn't use a stirrer rod, the port 30 c may be used to house the airline to the sparger at or near the bottom of the body or for any other desired purpose. Ports 32 a may be used for sampling of the liquid or for probes such as pH, temperature, dissolved oxygen, lactose level, etc. as are common on such bioreactors. Ports 32 a while shown as being formed on the sidewall 26 may also be formed in the bottom if desired as shown in FIG. 2 . Port 32 b is valved port which can be used to supply gas to the body 22 and/or as a drain or outlet from the body. It may serve both functions by attaching a 3 position valve or Y-shaped tube with valves such as pinch valves on each arm of the Y to control flow (not shown). One suitable system for the valve of port 32 b is a LYNX® connector available from Millipore Corporation of Billerica, Mass. and as shown in US Patent Publication No. 2005/0016620. [0034] Preferably, one or more ports 32 of the body are formed in a location that is below the normal liquid/gas interface level of the bioreactor. [0035] If desired, one or more of the ports 32 a or b in FIG. 1 may be used to provide gases to the body's interior. A plastic frit such as a POREX® porous material, a microporous membrane or ceramic stone or sintered metal filter may be attached to the inside of the port within the body to provide the sized gas bubbles desired. Alternatively, a port 30 a in the top 16 may be used to hold a tube that extends down into the body to provide the gas supply. Again it may use a frit or ceramic stone or sintered metal filter or a membrane to provide the desired bubble size. Alternatively, gases can be provided to the interior of the body through the porous filter/membrane 110 within the stirred cell assembly and the supply of gas can be provided through port 32 b. [0036] FIG. 2 shows a bioreactor 2 with top 16 and body 22 sealed to each other and a suitable stirring mechanism 14 in place. The stirring mechanism shown is formed of a shaft 40 and one or more paddles, circular disk, impellers, vanes or the like 42 . The shaft 40 extends through port 30 c and is connected to the shaft 20 of the drive mechanism 12 (not shown). Preferably one or more o-rings in the port 30 c allow for movement of the shaft 40 without compromising the integrity of the seal within the body 22 . Alternatively, the “agitation” to avoid plugging can be effected by ultrasonic waves or vibration directed at the membrane or filter surface to prevent the solids from collecting on the surface. Another method to prevent plugging the filter/membrane is to cause the solids to float to the top of the liquid phase by introducing gas bubbles which adhere to the solids. [0037] In accordance with certain embodiments, the bioreactor 22 is a cylindrical tube, and is removably and sealingly affixed to a base in order to provide a stirred cell assembly. For example, in the embodiment shown, shaft 40 is extended below paddle 42 via a short shaft portion 40 ′, and an additional paddle or the like 42 ′ is added ( FIG. 7 ). The paddle 42 ′ is preferably positioned just above the membrane 110 (discussed below) in the base in order to avoid contact with the membrane which could damage it. So positioned, it agitates the fluid just above the membrane and prevents solids (e.g., affinity beads, precipitate or floc) from settling on the membrane, which tend to clog or plug the pores of the membrane. Preferably the paddle is sufficiently wide such that it substantially corresponds to the width of the effective diameter of the membrane, or is slightly smaller than such width, in order to provide uniform fluid agitation over the effective filtration area of the membrane. In certain embodiments, the paddle 42 ′ can be constructed of a suitable material, such as rubber or a sponge-like material, so that contact with the surface of the membrane during agitation does not damage the membrane, and is acceptable, in order to further ensure that solids do not settle on the membrane surface. Those skilled in the art will appreciate that suitable means other than a paddle, such as a circular disk or wave agitation, to sufficiently agitate the fluid in the interior space of the body 22 , are within the scope of the embodiments disclosed herein. [0038] Turning to FIG. 3 , a bioreactor base 100 is shown, which includes a supporting surface 101 formed with grooves 102 or the like for the flow of fluid. The configuration of grooves 102 is not particularly limited, although the preferred configuration is concentric circles as illustrated. The grooves 102 are in fluid communication with an aperture 103 , which in turn is in fluid communication with port 32 b, for draining fluid from the base 100 . [0039] The surface 101 of the base 100 supports one or more membranes 110 ( FIG. 4 ). Preferably one of the one or more membranes is a relatively coarse filter or membrane, particularly when the solids content of the broth is high, such as about 20-35% solids by volume. Use of a coarse filter or membrane as an initial filtration step helps protect and prolong the service life of subsequent downstream filtration through tighter, generally more expensive membranes, such as a 0.2 micron sterilizing grade membrane (discussed in greater detail below). Suitable membranes include, but are not limited to, polymers such as but not limited to olefins such as polyethylene including ultrahigh molecular weight polyethylene, polypropylene, EVA copolymers and alpha olefins, metallocene olefinic polymers, PFA, MFA, PTFE, polycarbonates, vinyl copolymers such as PVC, polyamides such as nylon, polyesters, cellulose, cellulose acetate, regenerated cellulose, cellulose composites, polysulfone, polyethersulfone, polyarylsulfone, polyphenylsulfone, polyacrylonitrile, polyvinylidene fluoride (PVDF), and blends thereof. The membrane selected depends upon the application, desired filtration characteristics, particle type and size to be filtered and the flow desired. Preferred membrane based filters include DURAPORE® PVDF membranes available from Millipore Corporation of Billerica Mass., MILLIPORE EXPRESS® and MILLIPORE EXPRESS® PLUS or SH PES membranes available from Millipore Corporation of Billerica Mass. Prefilters, depth filters and the like can also be used in these embodiments such as Polygard® prefilters (Polygard CE prefilters) and depth filters (Polygard CR depth filters) available from Millipore Corporation of Billerica Mass. [0040] Depending on the mixture, polymer and the nature of biomolecule, the filter may be hydrophilic or hydrophobic. Preferred filters are hydrophilic and are low in protein binding. [0041] The filter, be it membrane or otherwise, may be symmetric in pore size throughout its depth such as DURAPORE® PVDF membranes available from Millipore Corporation of Billerica Mass., or it may be asymmetric in pore size through its thickness as with MILLIPORE EXPRESS® and MILLIPORE EXPRESS® PLUS or SH PES membranes available from Millipore Corporation of Billerica Mass. It may contain a prefilter layer if desired, either as a separate upstream layer or as an integral upstream portion of the membrane itself. [0042] Depending on the size of the particles generated, there may be instances in which the membrane is an ultrafiltration membrane. For example, in cases in which the particle size is small compared to the pore size of a microporous membrane, then a membrane with smaller pores (in the UF range) would be more appropriate to avoid plugging. Suitable ultrafiltration membranes include regenerated cellulose and polyethersulfone membranes, including those with a pore size larger than 0.2 microns, e.g., generally those with pore sizes of 0.45, 0.65, 1.0, 2.0 microns or larger. Optionally a porous support (not shown) can be placed between the surface 101 of the base and the membrane(s) 110 . The membrane(s) (and support if present) are sealed against the base such as with an O-ring 106 , which in turn can be held in place by a support ring 107 , such as an acrylic ring. Where more than one membrane 110 is used, they can be assembled in a stacked relationship. Where more than one membrane is used, each membrane need not be of the same performance characteristics (e.g, pore size, flux, capacity, surface chemistry, etc). For example, the upper membrane against the paddle 42 ′ may be of a larger pore size than the lower membrane(s) and/or it may be of a different material than the lower membrane(s). [0043] The bioreactor body 22 , such as a cylindrical tube, is placed in sealing relationship with the base 100 , as shown in FIG. 5 . A plurality of legs 6 ′ can be provided, which extend downwardly from the base 100 to support the same. [0044] In certain embodiments, where additional purification is desired, a further filter base can be added to the assembly, as shown in FIGS. 5 and 6 . Thus, a base 100 ′, similar to base 100 , is provided, again with a supporting surface having suitable grooves, and one or more membranes sealingly supported thereon, such as with a suitable 0 -ring and support ring. For example, a sterilizing membrane, such as a 0.2 micron membrane, can be used (optionally along with a suitable porous support). Sealed to the filter base 100 ′ is a housing 22 ′, which provides a cavity or interior space between the bioreactor base 100 and the filter base 100 ′. The housing 22 ′ can be a cylindrical tube, preferably having the same diameter as the bioreactor housing 22 , and made of the same material. It should have a height sufficient to accommodate at least a portion of the volume of fluid to be purified that is received directly from the bioreactor. The top edge of the housing 22 ′ preferably protrudes radially inwardly, and preferably includes an O-ring 106 ′ so that the housing 22 ′ and base 100 can be affixed in sealing relation. A plurality of legs 6 ″ can be provided, extending downwardly from the base 100 ′ to support the assembly. Although it is preferred that the filter base 100 ′ be integral to the bioreactor assembly to form a one-piece reactor assembly for sample processing and direct purification, in certain embodiments this subsequent purification step could be carried out with a filter that is physically separate from (although optionally in fluid communication with) the bioreactor body 22 . [0045] The housing 22 ′ includes an inlet port 50 that can be placed in fluid communication with the outlet 32 b of the base 100 , such as with suitable tubing 51 ( FIG. 5 ). The filter base 100 ′ includes an outlet port 32 b ′ in fluid communication with the drain (not shown) in the base, for directing the biomolecule of interest to a suitable point of use, such as a further purification step (e.g, a chromatography process train). [0046] An alternative embodiment is to have the outlet of the second housing 22 ′ in fluid communication with the outlet 32 of the base 100 but to have the second housing contain no filter or membrane. Instead the outlet port 32 ′ is in fluid communication via a tube or other conduit (not shown) with a self contained filter device (not shown) such as a Millex® filter or an Optiscale® or Opticap® filter that then sterile filters the biomolecule of interest. The outlet of this filter device is then connected to a suitable point of use, such as a further purification step (e.g., a chromatography process train). [0047] Suitable valving and sensing equipment can be associated with one or more of the various inlets and outlets to detect or measure and control flow or any other characteristic, such as the presence of the biomolecule or the presence of impurities, as appropriate or desired. For example, during the cell culture phase, the outlet 32 b of the base 100 is closed so that the fluid remains in the body 22 when the gas is applied through port 32 a or 30 a. [0048] In certain embodiments where a polymer is added to a cell culture broth to selectively and releasably bind a biomolecule of interest, suitable polymers include poly(N-vinyl caprolactam), poly(N-acryloylpiperidine), poly(N-vinylisobutyramide), poly(N-substituted acrylamide) including [poly(N-isopropylacrylamide), poly(N,N′-diethylacrylamide), and poly(N-acryloyl-N-alkylpiperazine)], Hydroxyalkylcellulose, copolymers of acrylic acid and methacrylic acid, polymers and copolymers of 2 or 4-vinylpyridine and chitosan with either a ligand or functional group attached to it. [0049] Suitable biomolecules of interest include proteins and antibodies. Suitable antibodies include antibody selected from the group consisting of a recombinant antibody, a recombinant monoclonal antibody, a polyclonal antibody, a humanized antibody and an antibody fragment. [0050] In operation, the sterile device is placed within the stand and the various connections for air, liquid, probes, sampling, etc. are attached to the device at the appropriate ports. The device is filled with media to a desired level forming a liquid/air interface somewhere below where the top 16 is attached to the body 22 to leave a head space of gas as is common in such devices. At least one port 32 is below the level of the interface. [0051] The media is then seeded with the organism to be grown, be it plant, animal cell (CHO or NSO cells for instance) virus, yeast, mold or bacteria (such as E. coli ) and the liquid is circulated or agitated and air/gases and liquids moved into or out of the device in a manner to effectively grow the culture inside. [0052] A polymer soluble under a certain set of process conditions is added, and is rendered insoluble and precipitates out of solution upon a change in conditions (e.g., temperature, salt concentration, light, electrical field, or pH). Alternatively, affinity or ion exchange beads or beads having any ligand or functionality capable of purifying the biomolecule can be added to bind to the biomolecule of interest or to the soluble impurities. Agitation is continued to inhibit the solids from settling, and the solid, which in this embodiment includes the precipitate that contains the polymer, impurities such as cells and cell debris, host cell proteins, DNA and the like and the desired biomolecule, can be washed one or more times (such as with a suitable buffer) to ensure that any impurities in the liquid or entrapped in or on the polymer have been removed. The wash step(s) can be carried out by filtration through the one or more membranes in the base 100 , with supernatant being sent to waste via port 32 b. [0053] The biomolecule of interest then can be recovered, such as by selective elution of the target biomolecule from the precipitate (or beads) such as by altering the ionic strength and/or pH conditions of the solution while the impurities, including soluble and insoluble material, remain complexed with the precipitated polymer. Recovery is carried out preferably along with a sterilizing filtration step, by causing the filtration base 100 ′ to be in fluid communication with the base 100 , such as by connecting the outlet of the base 100 to the inlet 50 of the body 22 ′. Accordingly, permeate from the outlet of the base 100 enters the body 22 ′, wets the membrane 110 ′, and filtration through the membrane 110 ′ proceeds. The purified biomolecule of interest is then recovered in the elution pool via the outlet port 32 b ′ of base 100 ′. The precipitated polymer-impurity complex (or the affinity beads) may be discarded. The driving force for filtration may be pressure or vacuum.
Container for sample preparation or processing, such as biomass culturing or processing, and optionally sample purification. In certain embodiments, the reactor is a bioreactor that includes a stirred cell device that simulates a tangential flow filter to reduce or eliminate clogging that can be caused by the solids generated. In certain embodiments, the solids comprise a precipitate or floc or beads, such as one that includes a polymer that binds the biomolecule(s) of interest, and impurities. In its method aspects, embodiments disclosed herein include purification and isolation of biomolecules of interest derived from cell culture fluids. The methods include carrying out sample preparation or processing in a container, culturing a biomass; generating solids by precipitating or flocculating a biomolecule of interest from the cultured broth; preventing the solids from settling in the container by agitation; and purification, such as by eluting the biomolecule of interest and filtering the same.
Provide a concise summary of the essential information conveyed in the given context.
[ "[0001] This application claims priority of Provisional Application Ser.", "No. 61/201,865 filed Dec. 16, 2008, the disclosure of which is hereby incorporated by reference.", "FIELD OF THE INVENTION [0002] The present invention relates to stirred tank containers, and related methods.", "BACKGROUND OF THE INVENTION [0003] The general process for the manufacture of biomolecules, such as proteins, particularly recombinant proteins, typically involves two main steps: (1) the expression of the protein in a host cell, followed by (2) the purification of the protein.", "The first step involves growing the desired host cell in a bioreactor to effect the expression of the protein.", "Some examples of cell lines used for this purpose include Chinese hamster ovary (CHO) cells, myeloma (NSO) bacterial cells such as e-coli and insect cells.", "Once the protein is expressed at the desired levels, the protein is removed from the host cell and harvested.", "Suspended particulates, such as cells, cell fragments, lipids and other insoluble matter are typically removed from the protein-containing fluid by filtration or centrifugation, resulting in a clarified fluid containing the protein of interest in solution as well as other soluble impurities.", "[0004] The second step involves the purification of the harvested protein to remove impurities which are inherent to the process.", "Examples of impurities include host cell proteins (HCP, proteins other than the desired or targeted protein), nucleic acids, endotoxins, viruses, protein variants and protein aggregates.", "This purification typically involves several chromatography steps, which can include affinity chromatography, ion exchange, hydrophobic interaction, etc.", "on solid matrices such as porous agarose, polymeric or glass or by membrane based adsorbers.", "[0005] One example of a chromatography process train for the purification of proteins involves protein-A affinity, followed by cation exchange, followed by anion exchange.", "The protein-A column captures the protein of interest or target protein by an affinity mechanism while the bulk of the impurities pass through the column to be discarded.", "The protein then is recovered by elution from the column.", "Since most of the proteins of interest have isoelectric points (PI) in the basic range (8-9) and therefore being positively charged under normal processing conditions (pH below the PI of the protein), they are bound to the cation exchange resin in the second column.", "Other positively charged impurities are also bound to this resin.", "The protein of interest is then recovered by elution from this column under conditions (pH, salt concentration) in which the protein elutes while the impurities remain bound to the resin.", "The anion exchange column is typically operated in a flow through mode, such that any negatively charged impurities are bound to the resin while the positively charged protein of interest is recovered in the flow through stream.", "This process results in a highly purified and concentrated protein solution.", "[0006] Other alternative methods for purifying proteins have been investigated in recent years.", "One such method involves a flocculation technique.", "In this technique, a soluble polyelectrolyte is added to an unclarified cell culture broth to capture the suspended particulates and a portion of the soluble impurities thereby forming a flocculant, which is subsequently removed from the protein solution by filtration or centrifugation.", "[0007] Alternatively, a soluble polyelectrolyte is added to clarified cell culture broth to capture the biomolecules of interest, thereby forming a flocculant, which is allowed to settle and can be subsequently isolated from the rest of the solution.", "The flocculant is typically washed to remove loosely adhering impurities.", "Afterwards, an increase in the solution's ionic strength brings about the dissociation of the target protein from the polyelectrolyte, subsequently resulting in the resolubilization of the polyelectrolyte into the protein-containing solution.", "[0008] In co-pending application U.S. Ser.", "No. 12/004,314 filed Dec. 20, 2007, the disclosure of which is hereby incorporated by reference, a polymer, soluble under certain conditions, such as temperature, pH, salt, light or combinations thereof, is used to bind impurities while in its soluble state and is then precipitated out upon a change in condition (pH or temperature, etc.) removing the impurities with it.", "The biomolecule of interest is then further treated using traditional chromatography or membrane adsorbers and the like.", "[0009] All of the protein purification technologies discussed above share a common theme, namely, to first remove suspended particulates in a first distinct step and then in a second step separate the biomolecules of interest from soluble impurities which are inherent to the process.", "[0010] In situ product recovery with derivatized magnetic particles is one example of a protein purification technique where the biomolecules of interest can be purified directly from an un-clarified cell culture broth.", "In this technique, a polymer shell encapsulating a magnetic bead is functionalized with an affinity ligand that seeks out and binds the target protein.", "A magnetic field is then applied to collect the bead-protein complexes, leaving behind the soluble impurities and insoluble particulates.", "[0011] The main drawback of this technique is that it requires appreciable capital investments in design, construction and validation of high-gradient magnetic separators.", "Also, the technique does not lend itself to disposable applications, which are poised to become the norm for protein purification in the Bioprocess industry.", "[0012] In co-pending application filed Dec. 16, 2008 under Attorney Docket No. MCA-1046, entitled “Purification of Proteins”", "by Moya, Wilson, et al.", ", the disclosure of which is hereby incorporated by reference, there is disclosed a polymer such as a soluble polymer capable of substantially irreversibly binding to insoluble particulates and a subset of soluble impurities and also capable of reversibly binding to one or more desired biomolecules in an unclarified biological material containing stream and the methods of using such a material to purify one or more desired biomolecules from such a stream without the need for prior clarification.", "More specifically, this co-pending application discloses a stimuli responsive polymer such as a selectively soluble polymer capable of selectively and reversibly binding to one or more desired biomolecules in an unclarified biological material containing stream and the methods of using such a polymer to purify one or more desired biomolecules from such a complex mixture of materials including the biomolecule(s) of interest and various impurities such as other proteins (host cell proteins), DNA, virus, whole cells, cellular debris and the like without the need for prior clarification of the stream.", "[0013] The polymer is soluble under a certain set of process conditions such as one or more of pH, salt concentration, temperature, light, or electrical field, and is able to interact and complex with insoluble impurities (cells, debris, etc.) and a fraction of the soluble impurities, and is rendered insoluble and precipitates out of solution upon a change in conditions (temperature, salt concentration, light, electrical field, or pH), e.g. a stimuli responsive polymer.", "Only when precipitated out of solution, the polymer is capable of reversibly binding to one or more desired biomolecules within the stream (protein, polypeptide, etc.) in an unclarified cell broth.", "The precipitate can then be removed from the stream, such as by being filtered out from the remainder of the stream and the desired biomolecule is recovered such as by selective elution from the precipitate.", "[0014] The removal of the precipitate, however, can be problematic, as it is typically in the form a large mass of sludge.", "[0015] It would be desirable to provide an apparatus and method for the efficient purification of samples, particularly those containing biomolecules, preferably within a single, integral, apparatus that reduces or eliminates one or more process steps that can result in contamination or material loss.", "SUMMARY OF THE INVENTION [0016] The problems of the prior art have been overcome by the embodiments disclosed herein, which include a container or housing for sample preparation or processing, such as biomass culturing or processing, and optionally sample purification.", "In certain embodiments, the container or housing is a mixer.", "In certain embodiments, the container or housing is a reactor.", "In certain embodiments, the reactor is a bioreactor, which can be disposable or reusable, that includes a stirred cell device that can simulate a tangential flow filter to reduce or eliminate clogging that can be caused by the solids generated.", "In certain embodiments, the solids comprise a precipitate or floc, such as one that includes a polymer that binds the biomolecule(s) of interest, and impurities such as cells and cell components.", "In certain embodiments, the stirred cell component includes one or more membranes for purification, such as during recovery (e.g., by elution) of the biomolecule(s) of interest.", "In certain embodiments, the biomolecules are proteins, polypeptides or antibodies.", "In certain embodiments, the container has two compartments.", "In certain embodiments the container has two compartments each of which has a membrane with it.", "In certain embodiments, the container has two compartments, the first having a membrane, the second being in fluid communication with a filter device downstream of the second compartment outlet.", "[0017] In its method aspects, embodiments disclosed herein include purification and isolation of biomolecules of interest derived from cell culture fluids.", "In certain embodiments, the methods include carrying out sample preparation or processing in a container or housing, such as culturing a biomass;", "generating solids such as by precipitating or flocculating a biomolecule of interest from the cultured broth;", "preventing the solids from settling in the container by agitation;", "and purification, such as by binding and eluting the biomolecule of interest and filtering the same.", "In certain embodiments, the sample processing involves expressing a protein of interest.", "In certain embodiments, the solids comprise a precipitate that includes a polymer bound to the protein of interest, and the purification involves binding and elution and one or more filtration steps.", "In certain embodiments, the solids comprise a precipitate that includes a polyelectrolyte bound to the protein of interest, and the purification involves binding and elution and one or more filtration steps.", "In certain embodiments, the polymer is bound to the impurities (cells, cell debris, etc.) and the biomolecule remains in the supernatant.", "The precipitation step may replace conventional chromatographic separations, may be used as a direct capture step to isolate the protein of interest from the cell culture broth, or may simply be an intermediate purification step.", "In certain embodiments, affinity or ion exchange beads or beads having any ligand or functionality capable of purifying the biomolecule may be used instead of a polymer to bind a biomolecule of interest.", "In certain embodiments, the one or more filtration steps are carried out in situ in the same apparatus as the sample processing.", "In certain embodiments, the eluted protein is subjected to further purification, such as by affinity and/or ion exchange chromatography.", "BRIEF DESCRIPTION OF THE DRAWINGS [0018] FIG. 1 is a perspective view of a bioreactor in accordance with certain embodiments;", "[0019] FIG. 2 is a cross-sectional view of a portion of the bioreactor of FIG. 1 ;", "[0020] FIG. 3 is a perspective view of a bioreactor base in accordance with certain embodiments;", "[0021] FIG. 4 is a perspective view of the base of FIG. 3 , including a membrane sealed thereon;", "[0022] FIG. 5 is a perspective view of a bioreactor assembly, including a housing, a bioreactor base, and a filtration base;", "[0023] FIG. 6 is a perspective view of a filtration base in accordance with certain embodiments;", "and [0024] FIG. 7 is a perspective view of an agitator in accordance with certain embodiments.", "DETAILED DESCRIPTION [0025] Suitable containers or housings useful here in useful herein are not particularly limited.", "For purposes of illustration, reactors, and in particular, bioreactors, will be discussed in detail, which include disposable as well as reusable bioreactors.", "For example, solvent-resistance bioreactors having a borosilicate glass cylinder and PTFE components, such as those commercially available from Millipore Corporation, can be used.", "Similarly, disposable bioreactors that utilize bags, or that are formed of semi-rigid or rigid molded plastic, can be used.", "Such disposable bioreactors are generally pre-sterilized.", "Means for agitation within the bioreactor is also not particularly limited, and includes impeller-based agitation, magnetic stirrers, as well as wave-induced agitation and agitation induced by gas bubbles.", "Agitation is important in preventing solids from settling and plugging the one or more membranes used for purification.", "[0026] The following description is in reference to a bioreactor.", "Those skilled in the art will appreciate that it is for illustrative purposes only, and that the embodiments disclosed herein are applicable to any container containing a liquid sample having, or ultimately forming, a sample having a relatively high solids content.", "[0027] Turning now to FIGS. 1 and 2 , bioreactor 2 is shown held in a stand 4 , which is comprised of several legs 6 (in this embodiment 3 legs although one continuous leg or 2 large legs or more than 3 legs can also be used) and a support rim 8 .", "As shown the legs 6 may have an optional support piece 10 at or near the bottom to keep the legs 6 from spreading when the bioreactor 2 is filled and in the stand 4 .", "[0028] Depending upon the type of circulation or agitation system used, the stand 4 may also support the drive mechanism 12 (as shown) for the circulation mechanism, which typically is a stirrer or paddle assembly 14 .", "In this particular embodiment, the drive mechanism 12 is a motor and is mounted to the top of the centered above the top 16 of the bioreactor 2 by several arms 18 (although 3 are shown alternative numbers may be used).", "Other features such as mounting blocks (not shown) and the like may be formed on the top 16 or support rim 8 to support the drive mechanism 12 .", "As shown, the drive mechanism 12 has a shaft 20 that can be attached to the stirrer as explained later herein.", "Other stands can be used in lieu of the design described above and will work equally well.", "[0029] The bioreactor body 22 (only partially shown in FIG. 1 ) has an interior space into which the fluids, cells, probes and other devices of the bioreactor are at least partially contained.", "The body 22 is sealably attached to the top 16 .", "This may be by a mechanical seal such as a rubber gasket and clips 24 (as shown) or by a clamp, such as a band clamp or Ladish or TriClover clamp, mated threads on the top 16 and body 22 and the like.", "Alternatively, they may be sealed by adhesives or heat sealing of the top 16 to the body 22 or formed together in one piece such as in a rotomolding apparatus.", "[0030] The body 22 has one or more sidewalls 26 that extend downwardly from the top 16 .", "As shown, there is one sidewall 26 of a circular or cylindrical design.", "Alternatively, there can be 3, 4, or more sidewalls if desired (not shown).", "[0031] Preferably, the body 22 is made of a single piece of molded plastic or glass.", "Alternatively it may be made of two or more pieces of plastic or glass that are sealed together such as by heat, glue, or gaskets (not shown).", "Suitable polymers which can be used to form the top and body include but are not limited to polycarbonates, polyesters, nylons, PTFE resins and other fluoropolymers, acrylic and methacrylic resins and copolymers, polysulphones, polyethersulphones, polyarylsulphones, polystyrenes, polyetherimides, nylons, polyesters, polyethylene terephthalates (PET), polyvinyl chlorides, chlorinated polyvinyl chlorides, ABS and its alloys and blends, polyolefins, preferably polyethylenes such as linear low density polyethylene, low density polyethylene, high density polyethylene, and ultrahigh molecular weight polyethylene and copolymers thereof, polypropylene and copolymers thereof and metallocene generated polyolefins.", "Preferred polymers are polyolefins, in particular polyethylenes and their copolymers;", "polystyrenes;", "and polycarbonates.", "The top and body may be made of the same polymer or different polymers as desired.", "In reusable embodiments, the body can be made of glass, acrylic, or other materials not deleterious to the process.", "The body 22 also can be a disposable plastic bag, as is known in the art.", "[0032] Also formed in the bioreactor 2 of this embodiment are one or more ports 30 (in this embodiment there are three types 30 a - c (for a total of 5 ports) formed in the top 16 and one or more ports 32 in the body 22 (in this embodiment there are at least two different types 32 a - b for a total of seven ports overall).", "The top 16 and body 22 may have multiple ports of similar and/or of different styles to provide one with the number of ports, of the desired type, in the desired locations throughout the bioreactor 2 .", "These ports 30 , 32 or at least a portion of them are formed as part of the top 16 and/or body 22 .", "They may be formed with threads that mate to sealable covers such as closed caps, gasketed caps with a throughbore within the gasket, or various Luer fittings.", "Alternatively, one or more of the ports can be made in the plastic top 16 and/or body 22 by drilling or burning a hole and then mounting (such as by heat bonding or adhesives) a port in place through or around the hole.", "Many different port styles and sizes can be accommodated.", "[0033] Ports 30 a may be used for liquid or gas entrance or exit or for probes such as pH probes, thermometers or thermocouples or the like.", "Ports 30 b may be used for similar purposes.", "Port 30 c is for the stirrer shaft described in further detail herein.", "Alternatively, if the bioreactor is an airlift design and doesn't use a stirrer rod, the port 30 c may be used to house the airline to the sparger at or near the bottom of the body or for any other desired purpose.", "Ports 32 a may be used for sampling of the liquid or for probes such as pH, temperature, dissolved oxygen, lactose level, etc.", "as are common on such bioreactors.", "Ports 32 a while shown as being formed on the sidewall 26 may also be formed in the bottom if desired as shown in FIG. 2 .", "Port 32 b is valved port which can be used to supply gas to the body 22 and/or as a drain or outlet from the body.", "It may serve both functions by attaching a 3 position valve or Y-shaped tube with valves such as pinch valves on each arm of the Y to control flow (not shown).", "One suitable system for the valve of port 32 b is a LYNX® connector available from Millipore Corporation of Billerica, Mass.", "and as shown in US Patent Publication No. 2005/0016620.", "[0034] Preferably, one or more ports 32 of the body are formed in a location that is below the normal liquid/gas interface level of the bioreactor.", "[0035] If desired, one or more of the ports 32 a or b in FIG. 1 may be used to provide gases to the body's interior.", "A plastic frit such as a POREX® porous material, a microporous membrane or ceramic stone or sintered metal filter may be attached to the inside of the port within the body to provide the sized gas bubbles desired.", "Alternatively, a port 30 a in the top 16 may be used to hold a tube that extends down into the body to provide the gas supply.", "Again it may use a frit or ceramic stone or sintered metal filter or a membrane to provide the desired bubble size.", "Alternatively, gases can be provided to the interior of the body through the porous filter/membrane 110 within the stirred cell assembly and the supply of gas can be provided through port 32 b. [0036] FIG. 2 shows a bioreactor 2 with top 16 and body 22 sealed to each other and a suitable stirring mechanism 14 in place.", "The stirring mechanism shown is formed of a shaft 40 and one or more paddles, circular disk, impellers, vanes or the like 42 .", "The shaft 40 extends through port 30 c and is connected to the shaft 20 of the drive mechanism 12 (not shown).", "Preferably one or more o-rings in the port 30 c allow for movement of the shaft 40 without compromising the integrity of the seal within the body 22 .", "Alternatively, the “agitation”", "to avoid plugging can be effected by ultrasonic waves or vibration directed at the membrane or filter surface to prevent the solids from collecting on the surface.", "Another method to prevent plugging the filter/membrane is to cause the solids to float to the top of the liquid phase by introducing gas bubbles which adhere to the solids.", "[0037] In accordance with certain embodiments, the bioreactor 22 is a cylindrical tube, and is removably and sealingly affixed to a base in order to provide a stirred cell assembly.", "For example, in the embodiment shown, shaft 40 is extended below paddle 42 via a short shaft portion 40 ′, and an additional paddle or the like 42 ′ is added ( FIG. 7 ).", "The paddle 42 ′ is preferably positioned just above the membrane 110 (discussed below) in the base in order to avoid contact with the membrane which could damage it.", "So positioned, it agitates the fluid just above the membrane and prevents solids (e.g., affinity beads, precipitate or floc) from settling on the membrane, which tend to clog or plug the pores of the membrane.", "Preferably the paddle is sufficiently wide such that it substantially corresponds to the width of the effective diameter of the membrane, or is slightly smaller than such width, in order to provide uniform fluid agitation over the effective filtration area of the membrane.", "In certain embodiments, the paddle 42 ′ can be constructed of a suitable material, such as rubber or a sponge-like material, so that contact with the surface of the membrane during agitation does not damage the membrane, and is acceptable, in order to further ensure that solids do not settle on the membrane surface.", "Those skilled in the art will appreciate that suitable means other than a paddle, such as a circular disk or wave agitation, to sufficiently agitate the fluid in the interior space of the body 22 , are within the scope of the embodiments disclosed herein.", "[0038] Turning to FIG. 3 , a bioreactor base 100 is shown, which includes a supporting surface 101 formed with grooves 102 or the like for the flow of fluid.", "The configuration of grooves 102 is not particularly limited, although the preferred configuration is concentric circles as illustrated.", "The grooves 102 are in fluid communication with an aperture 103 , which in turn is in fluid communication with port 32 b, for draining fluid from the base 100 .", "[0039] The surface 101 of the base 100 supports one or more membranes 110 ( FIG. 4 ).", "Preferably one of the one or more membranes is a relatively coarse filter or membrane, particularly when the solids content of the broth is high, such as about 20-35% solids by volume.", "Use of a coarse filter or membrane as an initial filtration step helps protect and prolong the service life of subsequent downstream filtration through tighter, generally more expensive membranes, such as a 0.2 micron sterilizing grade membrane (discussed in greater detail below).", "Suitable membranes include, but are not limited to, polymers such as but not limited to olefins such as polyethylene including ultrahigh molecular weight polyethylene, polypropylene, EVA copolymers and alpha olefins, metallocene olefinic polymers, PFA, MFA, PTFE, polycarbonates, vinyl copolymers such as PVC, polyamides such as nylon, polyesters, cellulose, cellulose acetate, regenerated cellulose, cellulose composites, polysulfone, polyethersulfone, polyarylsulfone, polyphenylsulfone, polyacrylonitrile, polyvinylidene fluoride (PVDF), and blends thereof.", "The membrane selected depends upon the application, desired filtration characteristics, particle type and size to be filtered and the flow desired.", "Preferred membrane based filters include DURAPORE® PVDF membranes available from Millipore Corporation of Billerica Mass.", ", MILLIPORE EXPRESS® and MILLIPORE EXPRESS® PLUS or SH PES membranes available from Millipore Corporation of Billerica Mass.", "Prefilters, depth filters and the like can also be used in these embodiments such as Polygard® prefilters (Polygard CE prefilters) and depth filters (Polygard CR depth filters) available from Millipore Corporation of Billerica Mass.", "[0040] Depending on the mixture, polymer and the nature of biomolecule, the filter may be hydrophilic or hydrophobic.", "Preferred filters are hydrophilic and are low in protein binding.", "[0041] The filter, be it membrane or otherwise, may be symmetric in pore size throughout its depth such as DURAPORE® PVDF membranes available from Millipore Corporation of Billerica Mass.", ", or it may be asymmetric in pore size through its thickness as with MILLIPORE EXPRESS® and MILLIPORE EXPRESS® PLUS or SH PES membranes available from Millipore Corporation of Billerica Mass.", "It may contain a prefilter layer if desired, either as a separate upstream layer or as an integral upstream portion of the membrane itself.", "[0042] Depending on the size of the particles generated, there may be instances in which the membrane is an ultrafiltration membrane.", "For example, in cases in which the particle size is small compared to the pore size of a microporous membrane, then a membrane with smaller pores (in the UF range) would be more appropriate to avoid plugging.", "Suitable ultrafiltration membranes include regenerated cellulose and polyethersulfone membranes, including those with a pore size larger than 0.2 microns, e.g., generally those with pore sizes of 0.45, 0.65, 1.0, 2.0 microns or larger.", "Optionally a porous support (not shown) can be placed between the surface 101 of the base and the membrane(s) 110 .", "The membrane(s) (and support if present) are sealed against the base such as with an O-ring 106 , which in turn can be held in place by a support ring 107 , such as an acrylic ring.", "Where more than one membrane 110 is used, they can be assembled in a stacked relationship.", "Where more than one membrane is used, each membrane need not be of the same performance characteristics (e.", "g, pore size, flux, capacity, surface chemistry, etc).", "For example, the upper membrane against the paddle 42 ′ may be of a larger pore size than the lower membrane(s) and/or it may be of a different material than the lower membrane(s).", "[0043] The bioreactor body 22 , such as a cylindrical tube, is placed in sealing relationship with the base 100 , as shown in FIG. 5 .", "A plurality of legs 6 ′ can be provided, which extend downwardly from the base 100 to support the same.", "[0044] In certain embodiments, where additional purification is desired, a further filter base can be added to the assembly, as shown in FIGS. 5 and 6 .", "Thus, a base 100 ′, similar to base 100 , is provided, again with a supporting surface having suitable grooves, and one or more membranes sealingly supported thereon, such as with a suitable 0 -ring and support ring.", "For example, a sterilizing membrane, such as a 0.2 micron membrane, can be used (optionally along with a suitable porous support).", "Sealed to the filter base 100 ′ is a housing 22 ′, which provides a cavity or interior space between the bioreactor base 100 and the filter base 100 ′.", "The housing 22 ′ can be a cylindrical tube, preferably having the same diameter as the bioreactor housing 22 , and made of the same material.", "It should have a height sufficient to accommodate at least a portion of the volume of fluid to be purified that is received directly from the bioreactor.", "The top edge of the housing 22 ′ preferably protrudes radially inwardly, and preferably includes an O-ring 106 ′ so that the housing 22 ′ and base 100 can be affixed in sealing relation.", "A plurality of legs 6 ″ can be provided, extending downwardly from the base 100 ′ to support the assembly.", "Although it is preferred that the filter base 100 ′ be integral to the bioreactor assembly to form a one-piece reactor assembly for sample processing and direct purification, in certain embodiments this subsequent purification step could be carried out with a filter that is physically separate from (although optionally in fluid communication with) the bioreactor body 22 .", "[0045] The housing 22 ′ includes an inlet port 50 that can be placed in fluid communication with the outlet 32 b of the base 100 , such as with suitable tubing 51 ( FIG. 5 ).", "The filter base 100 ′ includes an outlet port 32 b ′ in fluid communication with the drain (not shown) in the base, for directing the biomolecule of interest to a suitable point of use, such as a further purification step (e.", "g, a chromatography process train).", "[0046] An alternative embodiment is to have the outlet of the second housing 22 ′ in fluid communication with the outlet 32 of the base 100 but to have the second housing contain no filter or membrane.", "Instead the outlet port 32 ′ is in fluid communication via a tube or other conduit (not shown) with a self contained filter device (not shown) such as a Millex® filter or an Optiscale® or Opticap® filter that then sterile filters the biomolecule of interest.", "The outlet of this filter device is then connected to a suitable point of use, such as a further purification step (e.g., a chromatography process train).", "[0047] Suitable valving and sensing equipment can be associated with one or more of the various inlets and outlets to detect or measure and control flow or any other characteristic, such as the presence of the biomolecule or the presence of impurities, as appropriate or desired.", "For example, during the cell culture phase, the outlet 32 b of the base 100 is closed so that the fluid remains in the body 22 when the gas is applied through port 32 a or 30 a. [0048] In certain embodiments where a polymer is added to a cell culture broth to selectively and releasably bind a biomolecule of interest, suitable polymers include poly(N-vinyl caprolactam), poly(N-acryloylpiperidine), poly(N-vinylisobutyramide), poly(N-substituted acrylamide) including [poly(N-isopropylacrylamide), poly(N,N′-diethylacrylamide), and poly(N-acryloyl-N-alkylpiperazine)], Hydroxyalkylcellulose, copolymers of acrylic acid and methacrylic acid, polymers and copolymers of 2 or 4-vinylpyridine and chitosan with either a ligand or functional group attached to it.", "[0049] Suitable biomolecules of interest include proteins and antibodies.", "Suitable antibodies include antibody selected from the group consisting of a recombinant antibody, a recombinant monoclonal antibody, a polyclonal antibody, a humanized antibody and an antibody fragment.", "[0050] In operation, the sterile device is placed within the stand and the various connections for air, liquid, probes, sampling, etc.", "are attached to the device at the appropriate ports.", "The device is filled with media to a desired level forming a liquid/air interface somewhere below where the top 16 is attached to the body 22 to leave a head space of gas as is common in such devices.", "At least one port 32 is below the level of the interface.", "[0051] The media is then seeded with the organism to be grown, be it plant, animal cell (CHO or NSO cells for instance) virus, yeast, mold or bacteria (such as E. coli ) and the liquid is circulated or agitated and air/gases and liquids moved into or out of the device in a manner to effectively grow the culture inside.", "[0052] A polymer soluble under a certain set of process conditions is added, and is rendered insoluble and precipitates out of solution upon a change in conditions (e.g., temperature, salt concentration, light, electrical field, or pH).", "Alternatively, affinity or ion exchange beads or beads having any ligand or functionality capable of purifying the biomolecule can be added to bind to the biomolecule of interest or to the soluble impurities.", "Agitation is continued to inhibit the solids from settling, and the solid, which in this embodiment includes the precipitate that contains the polymer, impurities such as cells and cell debris, host cell proteins, DNA and the like and the desired biomolecule, can be washed one or more times (such as with a suitable buffer) to ensure that any impurities in the liquid or entrapped in or on the polymer have been removed.", "The wash step(s) can be carried out by filtration through the one or more membranes in the base 100 , with supernatant being sent to waste via port 32 b. [0053] The biomolecule of interest then can be recovered, such as by selective elution of the target biomolecule from the precipitate (or beads) such as by altering the ionic strength and/or pH conditions of the solution while the impurities, including soluble and insoluble material, remain complexed with the precipitated polymer.", "Recovery is carried out preferably along with a sterilizing filtration step, by causing the filtration base 100 ′ to be in fluid communication with the base 100 , such as by connecting the outlet of the base 100 to the inlet 50 of the body 22 ′.", "Accordingly, permeate from the outlet of the base 100 enters the body 22 ′, wets the membrane 110 ′, and filtration through the membrane 110 ′ proceeds.", "The purified biomolecule of interest is then recovered in the elution pool via the outlet port 32 b ′ of base 100 ′.", "The precipitated polymer-impurity complex (or the affinity beads) may be discarded.", "The driving force for filtration may be pressure or vacuum." ]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is related to pharmaceutical compositions useful for treating inflammation, and, particularly, to the potentiation of the activity of non-steroidal anti-inflammatory agents with cinanserin, a compound without anti-edema properties of its own. 2. Description of the Prior Art A major drawback to the treatment of inflammatory conditions with orally active non-steroidal anti-inflammatory drugs (NSAID) is the degree of gastric intolerance, bleeding, erosions and ulceration caused by this group of compounds, Boyle, E. et al, J. Pharm. Pharmac., 28, 865 (1976). Removal of this irritation by use of a combination of drugs to allow reduction of dosage without sacrificing clinical efficacy would constitute a significant therapeutic advance. However, simultaneous administration of two or more NSAID has not been found to produce an anti-inflammatory (AI) effect greater than that produced by either of them given alone at the same dose, Swingle, K. et al. J. Pharmacol. Exp. Ther. 172, 423 (1970). Accordingly, it is an object of this invention to potentiate the AI activity of a NSAID, such as indomethacin, by the simultaneous administration of a pharmacological compound which itself does not exhibit anti-edema properties, no matter how high the dose employed. In order for potentiation to be properly demonstrated, a drug without effect of its own must be shown to enhance the effect of an active drug, when the two are given together. SUMMARY OF THE INVENTION What is described herein is a pharmaceutical composition useful for treating inflammation in humans and animals which comprises an anti-inflammatory amount of a non-steroidal anti-inflammatory agent potentiated by being admixed with cinanserin, a pharmacological compound which itself does not exhibit anti-edema properties. In the preferred form of the invention, the combination of indomethacin and cinanserin provides a significant potentiation of the anti-inflammatory effect of idomethacin alone. IN THE DRAWINGS The FIGURE is a graphical representation of the anti-edma activity of indomethacin alone and in combination with cinanserin. DETAILED DESCRIPTION OF THE INVENTION The composition of the present invention normally is adapted for oral administration and, accordingly, may be presented as any conventional dosage form such as tablets, capsules, sachets of reconstitutable powder or the like. Most suitably the composition is in the form of a unit dose containing 20-200 mg. of the NSAID, e.g. 25 to 50 mg. and about 5-100 mg. of cinanserin, e.g. 10-50 mg. A preferred ratio of NSAID to cinanserin in a unit dose ranges from about 2:1 to 5:1. Such compositions may be administered once or more times per day so that the total daily dose for a 70 kg adult will be in the order of about 50-200 mg, for example, 75-150 mg. of the NSAID, and about 10-100 mg, for example, 25-50 mg. of cinanserin. The compositions may be prepared in conventional manner by mixing, filling, tabletting and the like and the compositions may contain conventional excipients such as lubricants, desintegrants, binders, fillers, coloring agents, flavors and the like. Typical NSAID agents include indomethacin, naproxen, ketoprofen, phenylbutazone and the like. The following description will be made with particular reference to indomethacin. Cinanserin is the chemical compound 2'-(3'dimethyl-aminopropylthio) cinnamanilide hydrochloride. PHARMACOLOGY The potentiation interaction between cinanserin and indomethacin was substantiated using the reduction of carrageenin induced edema in the pleural edema test on rats weighing about 330 g. as the test animal. A fixed dose of 31.6 mg/kg of cinanserin in combination with three dosage levels of indomethacin, 1 mg/kg, 3.16 mg/kg and 10 mg/kg was administered orally in the tests. No significant activity was observed for cinanserin alone at any dosage level, even as high as 360 mg/kg of the drug, in reduction of inflammation. The experimental results are given in the Table below and in the graphical representation in the FIGURE. They show a significant increase in potency for the combination of indomethacin and cinanserin as compared to indomethacin alone. TABLE__________________________________________________________________________Comparison of Anti-edema Activity of Indomethacin Aloneand in Combination with Cinanserin in Rat Pleural EdemaPrepar-ation Cont..sup.a Standard(Ind..sup.b alone) Cin..sup.c Test.sup.d (Ind. and Cin.)*__________________________________________________________________________Dose -- 1.0 3.16 10.0 31.6 1.0 3.16 10.0(mg/kg)Volume 6.9 6.3 5.4 4.7 6.8 5.8 5.0 4.6of PleuralExudate(ml)% Change -- -8.7 -21.7 -31.9 -1.4 -15.9 -27.5 -33.3fromCont.__________________________________________________________________________ .sup.a Cont. = Control rats received 1 ml/100 g of the vehicle (0.5% tragacanth). .sup.b Ind. = Indomethacin .sup.c Cin. = Cinanserin .sup.d Test preparation consisted of the stated dose of indomethacin plus 31.6 mg/kg of cinanserin in a total volume equal to that of the standard preparation. *Significantly more potent than the standard preparation.
The anti-inflammatory activity of non-steroidal anti-inflammatory agents are potentiated by the admixture with cinanserin, a compound which does not exhibit any anti-edema properties.
Summarize the document in concise, focusing on the main idea's functionality and advantages.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention The present invention is related to pharmaceutical compositions useful for treating inflammation, and, particularly, to the potentiation of the activity of non-steroidal anti-inflammatory agents with cinanserin, a compound without anti-edema properties of its own.", "Description of the Prior Art A major drawback to the treatment of inflammatory conditions with orally active non-steroidal anti-inflammatory drugs (NSAID) is the degree of gastric intolerance, bleeding, erosions and ulceration caused by this group of compounds, Boyle, E. et al, J. Pharm.", "Pharmac.", ", 28, 865 (1976).", "Removal of this irritation by use of a combination of drugs to allow reduction of dosage without sacrificing clinical efficacy would constitute a significant therapeutic advance.", "However, simultaneous administration of two or more NSAID has not been found to produce an anti-inflammatory (AI) effect greater than that produced by either of them given alone at the same dose, Swingle, K. et al.", "J. Pharmacol.", "Exp.", "Ther.", "172, 423 (1970).", "Accordingly, it is an object of this invention to potentiate the AI activity of a NSAID, such as indomethacin, by the simultaneous administration of a pharmacological compound which itself does not exhibit anti-edema properties, no matter how high the dose employed.", "In order for potentiation to be properly demonstrated, a drug without effect of its own must be shown to enhance the effect of an active drug, when the two are given together.", "SUMMARY OF THE INVENTION What is described herein is a pharmaceutical composition useful for treating inflammation in humans and animals which comprises an anti-inflammatory amount of a non-steroidal anti-inflammatory agent potentiated by being admixed with cinanserin, a pharmacological compound which itself does not exhibit anti-edema properties.", "In the preferred form of the invention, the combination of indomethacin and cinanserin provides a significant potentiation of the anti-inflammatory effect of idomethacin alone.", "IN THE DRAWINGS The FIGURE is a graphical representation of the anti-edma activity of indomethacin alone and in combination with cinanserin.", "DETAILED DESCRIPTION OF THE INVENTION The composition of the present invention normally is adapted for oral administration and, accordingly, may be presented as any conventional dosage form such as tablets, capsules, sachets of reconstitutable powder or the like.", "Most suitably the composition is in the form of a unit dose containing 20-200 mg.", "of the NSAID, e.g. 25 to 50 mg.", "and about 5-100 mg.", "of cinanserin, e.g. 10-50 mg.", "A preferred ratio of NSAID to cinanserin in a unit dose ranges from about 2:1 to 5:1.", "Such compositions may be administered once or more times per day so that the total daily dose for a 70 kg adult will be in the order of about 50-200 mg, for example, 75-150 mg.", "of the NSAID, and about 10-100 mg, for example, 25-50 mg.", "of cinanserin.", "The compositions may be prepared in conventional manner by mixing, filling, tabletting and the like and the compositions may contain conventional excipients such as lubricants, desintegrants, binders, fillers, coloring agents, flavors and the like.", "Typical NSAID agents include indomethacin, naproxen, ketoprofen, phenylbutazone and the like.", "The following description will be made with particular reference to indomethacin.", "Cinanserin is the chemical compound 2'-(3'dimethyl-aminopropylthio) cinnamanilide hydrochloride.", "PHARMACOLOGY The potentiation interaction between cinanserin and indomethacin was substantiated using the reduction of carrageenin induced edema in the pleural edema test on rats weighing about 330 g. as the test animal.", "A fixed dose of 31.6 mg/kg of cinanserin in combination with three dosage levels of indomethacin, 1 mg/kg, 3.16 mg/kg and 10 mg/kg was administered orally in the tests.", "No significant activity was observed for cinanserin alone at any dosage level, even as high as 360 mg/kg of the drug, in reduction of inflammation.", "The experimental results are given in the Table below and in the graphical representation in the FIGURE.", "They show a significant increase in potency for the combination of indomethacin and cinanserin as compared to indomethacin alone.", "TABLE__________________________________________________________________________Comparison of Anti-edema Activity of Indomethacin Aloneand in Combination with Cinanserin in Rat Pleural EdemaPrepar-ation Cont..", "sup.", "a Standard(Ind..", "sup.", "b alone) Cin..", "sup.", "c Test.", "sup.", "d (Ind.", "and Cin.)*__________________________________________________________________________Dose -- 1.0 3.16 10.0 31.6 1.0 3.16 10.0(mg/kg)Volume 6.9 6.3 5.4 4.7 6.8 5.8 5.0 4.6of PleuralExudate(ml)% Change -- -8.7 -21.7 -31.9 -1.4 -15.9 -27.5 -33.3fromCont.", "__________________________________________________________________________ .", "sup.", "a Cont.", "= Control rats received 1 ml/100 g of the vehicle (0.5% tragacanth).", "sup.", "b Ind.", "= Indomethacin .", "sup.", "c Cin.", "= Cinanserin .", "sup.", "d Test preparation consisted of the stated dose of indomethacin plus 31.6 mg/kg of cinanserin in a total volume equal to that of the standard preparation.", "*Significantly more potent than the standard preparation." ]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer readable medium storing a game program and to an information processing apparatus which reads information from a recording medium during an operation thereof. 2. Description of the Related Art As is well known, a software to operate an information processing apparatus (that is, a computer, a game machine, etc.) is composed of programs and several pieces of data utilized by the programs, and is distributed through a recording medium in a disk shape (for example, a flexible disk, CD-ROM, etc.). At a time of an execution of the software, a part of the software (that is, program or data) in the recording medium is read out and written over useless information on a RAM of the information processing apparatus. More concretely, a game software for use in an information processing apparatus (a personal computer or a game machine) is distributed through a CD-ROM 100 having a configuration as shown in FIG. 1, for example. That is, the CD-ROM 100 is generally pressed such that a game program including a main program and a plurality of program codes is recorded in a recording area 100 c at an inner radius side on the disk plane thereof, a group of animation data is recorded in a recording area 100 a at its outer radius side, and a group of graphic data is recorded in a recording area 100 b therebetween. In other words, a recording area composed of contiguous storage locations (sectors) that exist near the center of the CD-ROM 100 is used for storing the game program, and a recording area composed of contiguous storage locations that exist near the outer edge of the CD-ROM 100 is used for storing the animation data. Furthermore, the program codes, the animation data, the graphic data and the likes are recorded in the CD-ROM 100 in a form where each information can be identified by a file name. The CPU in the information processing apparatus having a CD-ROM drive that is set with the CD-ROM 100 will operate as follows. At first, the CPU read out the main program within the recording area 100 c onto the RAM by controlling the CD-ROM drive. Thereafter, the CPU, in accordance with the main program in the RAM, reads out several units of information (usually, several program codes and several graphic data) from the CD-ROM 100 to the RAM. Then, the CPU begins a control using the information prepared on the RAM, and if a predetermined condition (for example, a condition for proceeding to a new stage) is fulfilled, it reads several information corresponding to the fulfilled condition, from the CD-ROM 100 , and stores them on the RAM to overwrite useless information. Then, it begins a control that utilizes this newly prepared information. Thus, in the information processing apparatus that is set with the CD-ROM 100 , processing to read out several pieces of information necessary for continuing the execution of program from the CD-ROM 100 and stored on the RAM is executed. The configuration of the CD-ROM 100 described above causes the CD-ROM drive to operate inefficiently at a time of this processing (hereinafter, it refers to as an update processing) That is, at a time of the update processing, usually, several graphic data and several program codes are read out from the CD-ROM 100 . But, in the CD-ROM 100 , these information are recorded in the recording areas that are separated each other. As a result, there are many occasions that the head of the CD-ROM drive is not located in a neighborhood of the recording area of the information in the CD-ROM 100 at the time when a read instruction for a certain information is issued to the CD-ROM drive during the update processing, which causes that a relatively long latency time is included in a response time (an access time) for each of the reading instructions. Further, in general information processing apparatus, two seek actions must be performed in the CD-ROM drive to read out two files consecutively recorded on the CD-ROM 100 . More specifically, the CD-ROM 100 causes the CD-ROM drive to operate inefficiently at a time of the updating processing, because information are recorded in the recording areas that are separated each other, and each information is recorded as a file. SUMMARY OF THE INVENTION It is an object of the present invention to provide a computer readable medium capable of operating an information processing apparatus without making a reading device of the apparatus perform a useless operation. It is another object of the present invention to provide an information processing apparatus operates at high speed. In order to achieve the above mentioned object, a computer readable medium which is readable by a computer having a memory through a reading device according to the present invention comprises a program recording area in which a main program to be executed by the computer to perform a game is recorded and a component recording area in which program components each of which is used by the computer executing the main program to display a game character are consecutively recorded. The main program recorded in the program recording area includes a routine for causing the reading device to read out a plurality of program components that are consecutively stored in the component recording area and for storing a some of the program components outputted by the reading device into a memory. The computer readable medium according to the present invention is so configured as to have the program recording area in which a main program is recorded and the component recording area in which program components each of which is used by the computer to display a game character are consecutively recorded. The main program which is recorded in the computer readable medium is executed by the computer to make the reading device, at a time when some of the program components is required, read out the program components that are consecutively recorded in the component recording area including said some of the program components and to make the computer write said some of the program components into the memory. By setting this recording medium to the reading device of the information processing apparatus such as a computer or a game machine, a reading of the necessary program components will be completed without causing the reading device to perform a useless operation. Accordingly, using the recording medium of the present invention, the information processing apparatus can be functioned in a state that a latency time is less, in other words, the information processing apparatus can be functioned much faster than the conventional ones. An information processing apparatus of the invention comprises a recording medium in which program components each of which is used for displaying a game character are recorded, a reading device for reading the program components from the recording medium, a memory for temporally storing some of the program components recorded in the recording medium and control means for controlling the reading device to read out a plurality of program components that are consecutively stored in the recording medium and for storing some of the program components read by the reading device into the memory. The information processing apparatus of the present invention is configured as to operate similarly to a computer set with the computer readable medium of the present invention. Accordingly, the information processing apparatus functions much faster than the conventional ones. Note that, in actualizing this information processing apparatus, it is not necessary to record a main program on the recording medium in which program components are recorded. Further, as the recording medium, every type of medium can be used, for example, a compact disc. BRIEF DESCRIPTION OF THE DRAWINGS Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which: FIG. 1 is an illustrative diagram showing a configuration of a general CD-ROM; FIG. 2 is a block diagram showing a schematic configuration of an information processing apparatus according to one embodiment of the present invention; FIG. 3 is an illustrative diagram showing a usage configuration of a RAM in the information processing apparatus; FIG. 4 is a diagram showing one example of image displayed on a display screen by the information processing apparatus; FIG. 5 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 3; FIGS. 6A, 6 B and 6 C are diagrams used for explanation of a program code and a graphic code displaying a player characters; FIGS. 7A, 7 B and 7 C are diagrams for illustrating a program code and a graphic code used for displaying an enemy characters # 1 ; FIG. 8 is a diagram showing one example of image displayed on the display screen by the information processing apparatus; FIG. 9 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 8; FIGS. 10A, 10 B and 10 C are diagrams used for explanation of a program code and a graphic code displaying an enemy characters # 2 ; FIG. 11 is a diagram showing one example of image displayed on the display screen by the information processing apparatus; FIG. 12 is an illustrative diagram showing a usage configuration of the RAM at a time of displaying the image shown in FIG. 11; FIGS. 13A, 13 B and 13 C are diagrams used for explanation of a program code and a graphic code used for displaying enemy character # 3 ; FIG. 14 is a diagram showing one example of image displayed on a display screen by the information processing apparatus; FIG. 15 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 14; FIG. 16 is a diagram showing one example of image displayed on a display screen by the information processing apparatus; FIG. 17 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 16; FIG. 18 is a diagram showing one example of image displayed on a display screen by the information processing apparatus; FIG. 19 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 18; FIG. 20 is a diagram showing one example of image displayed on a display screen by the information processing apparatus; FIG. 21 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 20; FIG. 22 is an illustrative diagram showing a configuration of a CD-ROM according to the embodiment; FIG. 23 is an illustrative diagram showing a usage status of the program recording area at the outer radius side in the CD-ROM; and FIG. 24 is an illustrative diagram showing the code table that is referred to at a time when reading the data, the codes from the CD-ROM; FIG. 25 is an illustrative diagram showing a procedure for reading the program components from the CD-ROM executed in the information processing apparatus. DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described more concretely with reference to the accompanying drawings. At first, with reference to FIG. 2, a hardware configuration of an information processing apparatus according to one embodiment of the present invention will be described. As shown in the figure, the information processing apparatus 20 according to the present embodiment includes, for example, a control unit 21 , a RAM 22 , a sound processing unit 23 , an input unit 24 , an MDEC 25 , a graphic processing unit 26 and a CD-ROM drive 27 , as the main components thereof. This information processing apparatus 20 is used in a state where it is connected to a display device 30 (so-called home television set) that includes a display screen 30 a and a speaker, through the graphic processing unit 26 and the sound processing unit 23 . The control unit 21 is composed of a CPU, a ROM and the likes. The control unit 21 (CPU) integratedly controls the respective units within the information processing apparatus 20 in accordance with the program stored in the RAM 22 (or ROM as the case may be). The CD-ROM drive 27 is a reading device for a CD-ROM 10 in which a software (that is, game program) that defines the operation procedures of the control unit 21 is recorded. The CD-ROM drive 27 read out data recorded in the outer radius side of the DC-ROM 10 at faster speed than the inner radius side. The sound processing unit 23 creates and outputs a sound signal to generate a voice, a music, a sound effect and the likes from the speaker built in the display device 30 . The sound processing unit 23 creates and outputs a sound signal, based on the data that is read out from the CD-ROM 10 and stored into the RAM 22 under the control of the control unit 21 . The input unit 24 is an interface through which a user inputs information to the information processing apparatus 20 . The respective units other than the input unit 24 in the information processing apparatus 20 are accommodated in a body, and the input unit 24 is accommodated in another device which is called controller and which is to be connected to the body through a cable. The information processing apparatus 20 may be the one of which input unit 24 and other units are accommodated in one body. The MDEC 25 is a circuit that is capable of executing an inverse DCT (discrete cosine transformation) operation at fast speed. The MDEC 25 is used for expanding compressed data (that is, the image data and the animation data that are compressed/recorded in the CD-ROM 10 ) in a format such as the JPEG (Joint Photographic Experts Group) or the MPEG (Moving Picture Expert Group). The graphic processing unit 26 contains a frame buffer, which draws an image (a polygon) corresponding to an instruction supplied from the control unit 21 on the frame buffer, and concurrently creates and outputs a video signal corresponding to the image drawn on the frame buffer. The graphic processing unit 26 also performs a processing to output a video signal based on the expansion result by the MDEC 25 . In the following, an operation of the information processing apparatus 20 , and a configuration of the CD-ROM 10 will be described in detail. At first, with reference to FIG. 3, a usage configuration of the RAM 22 will be discussed. As shown in the figure, the storage area of the RAM 22 is separated into a system area 22 a , a program area 22 b , a stage data area 22 c , a character control code area, a sound effect/audio data area 22 e and a stack area 22 f. The system area 22 a is an area in which an OS (operating system) of the information processing apparatus 20 is allocated. The system stack area 22 f is a work area of the OS. The program area 22 b is an area to which a main program recorded in the CD-ROM 10 is read in. Further, in this area, a code table (described in detail below) that is referred to at a time when the various types of codes contained in the CD-ROM 10 is read is also stored. The stage data area 22 c is an area into which a graphic data used for displaying a background image of a stage the video game is stored. The character control code area 22 d is an area into which information required for displaying game characters is stored. In this area, for every character that will appear on a stage in the video game, a graphic code defining a basic shape thereof and a program code for displaying the game character in the various attitudes, based on the graphic code are stored. More specifically, in the character control code area 22 d , several pairs of the graphic codes and the program codes (hereinafter, a pair of the program code and the graphic code is referred to as a program component) required for displaying the game characters are stored. The sound effect/audio data area 22 e is an area into which data to be reproduced as a voice, a music, a sound effect and the like are stored. Reading out the graphic data, the program components and the likes from the CD-ROM 10 to the RAM 22 is performed at each time when the video game on a new stage is started. As shown in FIG. 4, in a stage, a player character 50 , enemy character 51 (the enemy character # 1 ) and a background image 60 A are displayed on the display screen 30 a . At a time the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 5 . More specifically, a graphic data 65 A for the background image 60 A recorded in the CD-ROM 10 is read out and stored into the stage data area 22 c within the RAM 22 . Further, a program component 90 (which is a combination of a program code 70 and a graphic code 80 ) for displaying the player character in various attitudes, for example, as the ones 50 a , 50 b and 50 c shown in FIGS. 6A, 6 B and 6 C is read out from the CD-ROM land stored into the character control code area 22 d . A program component 91 (which is a combination of a program code 71 and a graphic code 81 ) for displaying the enemy character # 1 in various attitudes, for example, as the ones 51 a , 51 b and 51 c shown in FIGS. 7A, 7 B and 7 C is also read out from the CD-ROM 10 and stored into the character control code area 22 d. In another stage, the player character 50 , an enemy character 52 (an enemy character # 2 ) and a background image 60 B are displayed on the display screen 30 a as shown in FIG. 8 . At a time the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 9 . More specifically, a graphic data 65 B for the background image 60 B is read in to the stage data area 22 c . Further, the program component 90 (which is a combination of the program code 70 and the graphic code 80 ) for the player character 50 and a program component 92 (which is a combination of a program code 72 and a graphic code 82 ) for displaying the enemy character # 2 in various attitudes, for example, as the ones 52 a , 52 b and 52 c shown in FIGS. 10A, 10 B and 10 C is read in to the character control code area 22 d. In another stage, the player character 50 , an enemy character 53 (an enemy character # 3 ) and a background image 60 C are displayed on the display screen 30 a as shown in FIG. 11 . At a time the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 12 . More specifically, a graphic data 65 C for the background image 60 C is read in to the stage data area 22 c . Further, the program component 90 for the player character 50 and a program component 93 (which is a combination of a program code 63 and a graphic code 73 ) for displaying the enemy character # 3 in various attitudes, for example as the ones 53 a , 53 b and 53 c shown in FIGS. 13A, 13 B and 13 C are read in to the character control code area 22 d. In another stage, the player character 50 , the enemy characters 51 , 52 (the enemy characters # 1 , # 2 ) and a background image 60 D are displayed on the display screen 30 a as shown in FIG. 14 . At a time when the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 15 . More specifically, a graphic data 65 D for the background image 60 D is read in to the stage data area 22 c . Further, the program component 90 for the player character 50 , the program component 91 for the enemy character 51 and the program component 92 for the enemy character 52 are read in to the character control code area 22 d. In another stage, the player character 50 , the enemy characters 51 , 53 (the enemy characters # 1 , # 3 ) and a background image 60 E are displayed on the display screen 30 a as shown in FIG. 16 . At a time when the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 17 . More specifically, a graphic data 65 E for the background image 60 E is read in to the stage data area 22 c . Further, the program component 90 for the player character 50 , the program component 91 for the enemy character # 1 and the program component 93 for the enemy character # 2 are read in to the character control code area 22 d. In another stage, the player character 50 , the enemy characters 52 , 53 and a background image 60 F are displayed on the display screen 30 a as shown in FIG. 18 . At a time when the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 19 . More specifically, a graphic data 65 F for the background image 60 F is read in to the stage data area 22 c . Further, the program component 90 for the player character 50 , the program component 92 for the enemy character # 2 and the program component 93 for the enemy character # 3 are read in to the character control code area 22 d. In another stage, as shown in FIG. 20, the player character 50 , the enemy characters 51 through 53 and a background image 60 G are displayed on the display screen 30 a . At a time when the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 21 . More specifically, a graphic data 65 G for the background image 60 G is read in to the stage data area 22 c . Further, the program component 90 for the player character 50 , the program component 91 for the enemy character # 1 , the program component 92 for the enemy character # 2 and the program component 93 for the enemy character # 3 are read in to the character control code area 22 d. On the CD-ROM 10 , these pieces of information (graphic data, program codes, graphic codes, etc.) which are to be read out and stored in to the RAM 22 under the control of the main program are recorded in the configurations as shown in FIGS. 22, 23 . More specifically, the entire recording area on the CD-ROM 10 is divided into two program recording areas 10 a , 10 c and one animation data recording area 10 b as shown in FIG. 22 . The animation data recording area 10 b is equivalent to the recording area 100 a in the CD-ROM 100 shown in FIG. 1 . Animation data recording area 10 b is stored with movie data in the JPEG format or the MPEG format used at a time when the video game starts, and several movie data each used at a time when a specific event is occurred during an execution of a game, and the likes. Whole of the program recording areas 10 a , 10 c is equivalent to whole of the recording area 100 b and the recording area 100 c in the CD-ROM 100 . In the program recording area 10 c at the inner radius side on the CD-ROM 10 , the main program and the code table are recorded. In the program recording area 10 a at the outer radius side, the various kinds of information (that is, the graphic data for the background image, the program components, and the likes) that are to be read in to the RAM 22 under the control of the main program are recorded. In the program recording area 10 a , the plural program components are recorded consecutively. In this area where the program components are recorded (hereinafter, referred as to the component recording area) , the program components regarding the characters that may be displayed simultaneously are recorded in the proximity recording locations. For example, the above described player character 50 and the enemy characters 51 through 53 (the enemy characters # 1 through # 3 ) may be displayed simultaneously. Accordingly, the program components regarding these characters are, as schematically shown in FIG. 23, contiguonsly recorded in the component recording area 29 within the program recording area 10 a. Further, the CD-ROM 10 contains the above mentioned various kinds of information (the program, data, codes) as one file. Therefore, the code table read out from the CD-ROM 10 and written into RAM 22 is used for reading out the respective information from the CD-ROM 10 . Concretely, as schematically shown in FIG. 24, the code table 95 holds starting position information 96 of 4 bytes and size information 97 of 4 bytes for each of codes # 1 to #N. Here, N is a positive integer, and code #X (X is a integer, where 1≦X≦N) is a bulk of information, that is, the program component, the graphic data and the likes, which may be read singly. The starting position information 92 for the code #X indicates a starting position of the recording area where the code #X is recorded, and the size information 94 of the code #X indicates the size of the code #X. The main program contains instructions for reading out codes from the CD-ROM 10 , each of which includes the code number X corresponding to the code #X. More specifically, the main program causes, at a time when a code of the code number X is to be read out from the CD-ROM 10 into RAM 22 , the control unit 21 to obtain the starting position information 92 and the size information 94 corresponding to the code number X from the code table 90 , and to read out the information which is recorded within an area from the position (sector) that is defined by the obtained starting position information 92 , of which size is defined by the obtained size information 94 , on the CD-ROM 10 . Furthermore, the main program read into the program area 22 a includes routines which cause the control unit 21 to operate as follows. When updating the content of the RAM 22 in to the one shown in FIG. 9, namely, when the program component 90 and 92 are to be stored in the RAM 22 , the control unit 21 first instructs the CD-ROM drive 27 to output data stored in a series of contiguous storage locations which begins at the storage location of the program code 90 for the player character 50 and ends at the storage location of the graphic code 92 for the enemy character # 2 (see FIG. 23 ). More Specifically, as schematically shown in FIG. 25, the control unit 21 instructs the CD-ROM drive 27 to output the program components 90 , 91 , and 92 by issuing a instruction including a start address of the program component 90 and the size information indicating the total size of these three program components 90 , 91 and 92 . Then, the control unit 21 stores the program component 90 outputted from the CD-ROM drive 27 into the memory area on the RAM 22 , which begins at the address “0015 0000H”. Thereafter, the control unit 21 discards the program components 91 outputted from the CD-ROM drive 27 after the program component 90 , without processing the data, and store the program component 92 outputted from the CD-ROM drive 27 after the program component 91 into the memory area on the RAM 22 , which begins at the address “0017 0000H”. When updating the contents of the RAM 22 into the one shown in FIG. 12, the control unit 21 instructs the CD-ROM drive 27 to output data stored in a series of contiguous storage locations which begins at the storage location of the program code 90 for the player character, and ends at the storage location of the graphic code 93 for the enemy character # 3 . More specifically, the control unit 21 instructs the CD-ROM drive 27 to output four program components 90 trough 93 by issuing a instruction including a start address of the program component 90 and the size information indicating the total size of these program components 90 through 93 . Then, the control unit 21 stores the program component 90 outputted from the CD-ROM drive 27 into the RAM 22 . Thereafter, the control unit 21 discards the program components 91 and 92 outputted from the CD-ROM drive 27 after the program component 90 , and stores the program component 93 outputted from the CD-ROM drive 27 after the program component 92 in the RAM 22 . When updating the content of the RAM 22 into the one shown in FIG. 17 or FIG. 19, the control unit 21 also executes a similar procedure. More specifically, the control unit 21 instructs the CD-ROM drive 27 to output data which includes one or more unnecessary program components (that is, the program component 92 in FIG. 17 or the program component 91 in FIG. 9) along with plural necessary program components and which is stored at a series of contiguous storage locations on the CD-ROM 10 . Then, the control unit 21 stores only the necessary program components included in the output of the CD-ROM drive 27 into the RAM 22 . When updating the content of the RAM 22 into the one shown in FIG. 5, 15 or 21 , namely, when starting a stage of video game which needs some program components record at a series of contiguous storage locations on the CD-ROM 10 , the control unit 21 instructs the CD-ROM drive 27 to output data which consists of the necessary program components, and then stores all the program components outputted from the CD-ROM drive 27 into the RAM 22 . As described in detail above, the CD-ROM 10 is configured such that plural program components are recorded in one recording area (that is, contiguous storage locations). And the main program recorded in the CD-ROM 10 includes plural routines each for executing a load process, which consists of a process making the CD-ROM drive 27 outputs several program components with one seek action and a process to store some of program component among the program components outputted from the CD-ROM drive 27 in the RAM 22 . Consequently, the information processing apparatus 20 set with this CD-ROM 10 operates without making the CD-ROM drive 27 to perform uselessly, and therefore the information processing apparatus 20 can operate at faster speed than the apparatus set with the CD-ROM 100 shown in FIG. 1 . The CD-ROM 10 of the embodiment may be varied. For example, through the above mentioned CD-ROM 10 is such that the program components are recorded in the storage areas at the outer radius side on the disk, it is desirable to produce the CD-ROM such that the component recording area exists at the inner radius side on the disk when it is designed to be set in the CD-ROM drive in which an access to the data recorded at the inner radius side on the disk can be performed at fast speed. It may be arranged such that the program codes and the graphic codes, which constitute the program component, are to be written into areas separated each other, rather than into consecutive areas on the RAM 22 . In other words, the storage area for use in the program codes and the storage area for use in the graphic codes may be prepared on the RAM 22 , separately. Further, the above mentioned technology may be applied to a recording medium other than the CD-ROM (for example, a DVD or a hard disk). The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Disclosed is a computer readable medium capable of functioning an information processing apparatus without making a reading device to operate inefficiently. The recording medium comprises a main program storing area in which a main program for performing a game is recorded and a component recording area in which program components each of which is used for displaying a game character are consecutively recorded. The main program recorded in the main program storing area includes a routine for causing the reading device to read out a plurality of program components that are consecutively stored in the component recording area and for causing a control unit of the apparatus to store some of program components included in the plurality of program components read by the reading device into a memory.
Concisely explain the essential features and purpose of the invention.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention The present invention relates to a computer readable medium storing a game program and to an information processing apparatus which reads information from a recording medium during an operation thereof.", "Description of the Related Art As is well known, a software to operate an information processing apparatus (that is, a computer, a game machine, etc.) is composed of programs and several pieces of data utilized by the programs, and is distributed through a recording medium in a disk shape (for example, a flexible disk, CD-ROM, etc.).", "At a time of an execution of the software, a part of the software (that is, program or data) in the recording medium is read out and written over useless information on a RAM of the information processing apparatus.", "More concretely, a game software for use in an information processing apparatus (a personal computer or a game machine) is distributed through a CD-ROM 100 having a configuration as shown in FIG. 1, for example.", "That is, the CD-ROM 100 is generally pressed such that a game program including a main program and a plurality of program codes is recorded in a recording area 100 c at an inner radius side on the disk plane thereof, a group of animation data is recorded in a recording area 100 a at its outer radius side, and a group of graphic data is recorded in a recording area 100 b therebetween.", "In other words, a recording area composed of contiguous storage locations (sectors) that exist near the center of the CD-ROM 100 is used for storing the game program, and a recording area composed of contiguous storage locations that exist near the outer edge of the CD-ROM 100 is used for storing the animation data.", "Furthermore, the program codes, the animation data, the graphic data and the likes are recorded in the CD-ROM 100 in a form where each information can be identified by a file name.", "The CPU in the information processing apparatus having a CD-ROM drive that is set with the CD-ROM 100 will operate as follows.", "At first, the CPU read out the main program within the recording area 100 c onto the RAM by controlling the CD-ROM drive.", "Thereafter, the CPU, in accordance with the main program in the RAM, reads out several units of information (usually, several program codes and several graphic data) from the CD-ROM 100 to the RAM.", "Then, the CPU begins a control using the information prepared on the RAM, and if a predetermined condition (for example, a condition for proceeding to a new stage) is fulfilled, it reads several information corresponding to the fulfilled condition, from the CD-ROM 100 , and stores them on the RAM to overwrite useless information.", "Then, it begins a control that utilizes this newly prepared information.", "Thus, in the information processing apparatus that is set with the CD-ROM 100 , processing to read out several pieces of information necessary for continuing the execution of program from the CD-ROM 100 and stored on the RAM is executed.", "The configuration of the CD-ROM 100 described above causes the CD-ROM drive to operate inefficiently at a time of this processing (hereinafter, it refers to as an update processing) That is, at a time of the update processing, usually, several graphic data and several program codes are read out from the CD-ROM 100 .", "But, in the CD-ROM 100 , these information are recorded in the recording areas that are separated each other.", "As a result, there are many occasions that the head of the CD-ROM drive is not located in a neighborhood of the recording area of the information in the CD-ROM 100 at the time when a read instruction for a certain information is issued to the CD-ROM drive during the update processing, which causes that a relatively long latency time is included in a response time (an access time) for each of the reading instructions.", "Further, in general information processing apparatus, two seek actions must be performed in the CD-ROM drive to read out two files consecutively recorded on the CD-ROM 100 .", "More specifically, the CD-ROM 100 causes the CD-ROM drive to operate inefficiently at a time of the updating processing, because information are recorded in the recording areas that are separated each other, and each information is recorded as a file.", "SUMMARY OF THE INVENTION It is an object of the present invention to provide a computer readable medium capable of operating an information processing apparatus without making a reading device of the apparatus perform a useless operation.", "It is another object of the present invention to provide an information processing apparatus operates at high speed.", "In order to achieve the above mentioned object, a computer readable medium which is readable by a computer having a memory through a reading device according to the present invention comprises a program recording area in which a main program to be executed by the computer to perform a game is recorded and a component recording area in which program components each of which is used by the computer executing the main program to display a game character are consecutively recorded.", "The main program recorded in the program recording area includes a routine for causing the reading device to read out a plurality of program components that are consecutively stored in the component recording area and for storing a some of the program components outputted by the reading device into a memory.", "The computer readable medium according to the present invention is so configured as to have the program recording area in which a main program is recorded and the component recording area in which program components each of which is used by the computer to display a game character are consecutively recorded.", "The main program which is recorded in the computer readable medium is executed by the computer to make the reading device, at a time when some of the program components is required, read out the program components that are consecutively recorded in the component recording area including said some of the program components and to make the computer write said some of the program components into the memory.", "By setting this recording medium to the reading device of the information processing apparatus such as a computer or a game machine, a reading of the necessary program components will be completed without causing the reading device to perform a useless operation.", "Accordingly, using the recording medium of the present invention, the information processing apparatus can be functioned in a state that a latency time is less, in other words, the information processing apparatus can be functioned much faster than the conventional ones.", "An information processing apparatus of the invention comprises a recording medium in which program components each of which is used for displaying a game character are recorded, a reading device for reading the program components from the recording medium, a memory for temporally storing some of the program components recorded in the recording medium and control means for controlling the reading device to read out a plurality of program components that are consecutively stored in the recording medium and for storing some of the program components read by the reading device into the memory.", "The information processing apparatus of the present invention is configured as to operate similarly to a computer set with the computer readable medium of the present invention.", "Accordingly, the information processing apparatus functions much faster than the conventional ones.", "Note that, in actualizing this information processing apparatus, it is not necessary to record a main program on the recording medium in which program components are recorded.", "Further, as the recording medium, every type of medium can be used, for example, a compact disc.", "BRIEF DESCRIPTION OF THE DRAWINGS Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which: FIG. 1 is an illustrative diagram showing a configuration of a general CD-ROM;", "FIG. 2 is a block diagram showing a schematic configuration of an information processing apparatus according to one embodiment of the present invention;", "FIG. 3 is an illustrative diagram showing a usage configuration of a RAM in the information processing apparatus;", "FIG. 4 is a diagram showing one example of image displayed on a display screen by the information processing apparatus;", "FIG. 5 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 3;", "FIGS. 6A, 6 B and 6 C are diagrams used for explanation of a program code and a graphic code displaying a player characters;", "FIGS. 7A, 7 B and 7 C are diagrams for illustrating a program code and a graphic code used for displaying an enemy characters # 1 ;", "FIG. 8 is a diagram showing one example of image displayed on the display screen by the information processing apparatus;", "FIG. 9 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 8;", "FIGS. 10A, 10 B and 10 C are diagrams used for explanation of a program code and a graphic code displaying an enemy characters # 2 ;", "FIG. 11 is a diagram showing one example of image displayed on the display screen by the information processing apparatus;", "FIG. 12 is an illustrative diagram showing a usage configuration of the RAM at a time of displaying the image shown in FIG. 11;", "FIGS. 13A, 13 B and 13 C are diagrams used for explanation of a program code and a graphic code used for displaying enemy character # 3 ;", "FIG. 14 is a diagram showing one example of image displayed on a display screen by the information processing apparatus;", "FIG. 15 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 14;", "FIG. 16 is a diagram showing one example of image displayed on a display screen by the information processing apparatus;", "FIG. 17 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 16;", "FIG. 18 is a diagram showing one example of image displayed on a display screen by the information processing apparatus;", "FIG. 19 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 18;", "FIG. 20 is a diagram showing one example of image displayed on a display screen by the information processing apparatus;", "FIG. 21 is an illustrative diagram showing a usage status of the RAM at a time of displaying the image shown in FIG. 20;", "FIG. 22 is an illustrative diagram showing a configuration of a CD-ROM according to the embodiment;", "FIG. 23 is an illustrative diagram showing a usage status of the program recording area at the outer radius side in the CD-ROM;", "and FIG. 24 is an illustrative diagram showing the code table that is referred to at a time when reading the data, the codes from the CD-ROM;", "FIG. 25 is an illustrative diagram showing a procedure for reading the program components from the CD-ROM executed in the information processing apparatus.", "DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described more concretely with reference to the accompanying drawings.", "At first, with reference to FIG. 2, a hardware configuration of an information processing apparatus according to one embodiment of the present invention will be described.", "As shown in the figure, the information processing apparatus 20 according to the present embodiment includes, for example, a control unit 21 , a RAM 22 , a sound processing unit 23 , an input unit 24 , an MDEC 25 , a graphic processing unit 26 and a CD-ROM drive 27 , as the main components thereof.", "This information processing apparatus 20 is used in a state where it is connected to a display device 30 (so-called home television set) that includes a display screen 30 a and a speaker, through the graphic processing unit 26 and the sound processing unit 23 .", "The control unit 21 is composed of a CPU, a ROM and the likes.", "The control unit 21 (CPU) integratedly controls the respective units within the information processing apparatus 20 in accordance with the program stored in the RAM 22 (or ROM as the case may be).", "The CD-ROM drive 27 is a reading device for a CD-ROM 10 in which a software (that is, game program) that defines the operation procedures of the control unit 21 is recorded.", "The CD-ROM drive 27 read out data recorded in the outer radius side of the DC-ROM 10 at faster speed than the inner radius side.", "The sound processing unit 23 creates and outputs a sound signal to generate a voice, a music, a sound effect and the likes from the speaker built in the display device 30 .", "The sound processing unit 23 creates and outputs a sound signal, based on the data that is read out from the CD-ROM 10 and stored into the RAM 22 under the control of the control unit 21 .", "The input unit 24 is an interface through which a user inputs information to the information processing apparatus 20 .", "The respective units other than the input unit 24 in the information processing apparatus 20 are accommodated in a body, and the input unit 24 is accommodated in another device which is called controller and which is to be connected to the body through a cable.", "The information processing apparatus 20 may be the one of which input unit 24 and other units are accommodated in one body.", "The MDEC 25 is a circuit that is capable of executing an inverse DCT (discrete cosine transformation) operation at fast speed.", "The MDEC 25 is used for expanding compressed data (that is, the image data and the animation data that are compressed/recorded in the CD-ROM 10 ) in a format such as the JPEG (Joint Photographic Experts Group) or the MPEG (Moving Picture Expert Group).", "The graphic processing unit 26 contains a frame buffer, which draws an image (a polygon) corresponding to an instruction supplied from the control unit 21 on the frame buffer, and concurrently creates and outputs a video signal corresponding to the image drawn on the frame buffer.", "The graphic processing unit 26 also performs a processing to output a video signal based on the expansion result by the MDEC 25 .", "In the following, an operation of the information processing apparatus 20 , and a configuration of the CD-ROM 10 will be described in detail.", "At first, with reference to FIG. 3, a usage configuration of the RAM 22 will be discussed.", "As shown in the figure, the storage area of the RAM 22 is separated into a system area 22 a , a program area 22 b , a stage data area 22 c , a character control code area, a sound effect/audio data area 22 e and a stack area 22 f. The system area 22 a is an area in which an OS (operating system) of the information processing apparatus 20 is allocated.", "The system stack area 22 f is a work area of the OS.", "The program area 22 b is an area to which a main program recorded in the CD-ROM 10 is read in.", "Further, in this area, a code table (described in detail below) that is referred to at a time when the various types of codes contained in the CD-ROM 10 is read is also stored.", "The stage data area 22 c is an area into which a graphic data used for displaying a background image of a stage the video game is stored.", "The character control code area 22 d is an area into which information required for displaying game characters is stored.", "In this area, for every character that will appear on a stage in the video game, a graphic code defining a basic shape thereof and a program code for displaying the game character in the various attitudes, based on the graphic code are stored.", "More specifically, in the character control code area 22 d , several pairs of the graphic codes and the program codes (hereinafter, a pair of the program code and the graphic code is referred to as a program component) required for displaying the game characters are stored.", "The sound effect/audio data area 22 e is an area into which data to be reproduced as a voice, a music, a sound effect and the like are stored.", "Reading out the graphic data, the program components and the likes from the CD-ROM 10 to the RAM 22 is performed at each time when the video game on a new stage is started.", "As shown in FIG. 4, in a stage, a player character 50 , enemy character 51 (the enemy character # 1 ) and a background image 60 A are displayed on the display screen 30 a .", "At a time the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 5 .", "More specifically, a graphic data 65 A for the background image 60 A recorded in the CD-ROM 10 is read out and stored into the stage data area 22 c within the RAM 22 .", "Further, a program component 90 (which is a combination of a program code 70 and a graphic code 80 ) for displaying the player character in various attitudes, for example, as the ones 50 a , 50 b and 50 c shown in FIGS. 6A, 6 B and 6 C is read out from the CD-ROM land stored into the character control code area 22 d .", "A program component 91 (which is a combination of a program code 71 and a graphic code 81 ) for displaying the enemy character # 1 in various attitudes, for example, as the ones 51 a , 51 b and 51 c shown in FIGS. 7A, 7 B and 7 C is also read out from the CD-ROM 10 and stored into the character control code area 22 d. In another stage, the player character 50 , an enemy character 52 (an enemy character # 2 ) and a background image 60 B are displayed on the display screen 30 a as shown in FIG. 8 .", "At a time the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 9 .", "More specifically, a graphic data 65 B for the background image 60 B is read in to the stage data area 22 c .", "Further, the program component 90 (which is a combination of the program code 70 and the graphic code 80 ) for the player character 50 and a program component 92 (which is a combination of a program code 72 and a graphic code 82 ) for displaying the enemy character # 2 in various attitudes, for example, as the ones 52 a , 52 b and 52 c shown in FIGS. 10A, 10 B and 10 C is read in to the character control code area 22 d. In another stage, the player character 50 , an enemy character 53 (an enemy character # 3 ) and a background image 60 C are displayed on the display screen 30 a as shown in FIG. 11 .", "At a time the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 12 .", "More specifically, a graphic data 65 C for the background image 60 C is read in to the stage data area 22 c .", "Further, the program component 90 for the player character 50 and a program component 93 (which is a combination of a program code 63 and a graphic code 73 ) for displaying the enemy character # 3 in various attitudes, for example as the ones 53 a , 53 b and 53 c shown in FIGS. 13A, 13 B and 13 C are read in to the character control code area 22 d. In another stage, the player character 50 , the enemy characters 51 , 52 (the enemy characters # 1 , # 2 ) and a background image 60 D are displayed on the display screen 30 a as shown in FIG. 14 .", "At a time when the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 15 .", "More specifically, a graphic data 65 D for the background image 60 D is read in to the stage data area 22 c .", "Further, the program component 90 for the player character 50 , the program component 91 for the enemy character 51 and the program component 92 for the enemy character 52 are read in to the character control code area 22 d. In another stage, the player character 50 , the enemy characters 51 , 53 (the enemy characters # 1 , # 3 ) and a background image 60 E are displayed on the display screen 30 a as shown in FIG. 16 .", "At a time when the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 17 .", "More specifically, a graphic data 65 E for the background image 60 E is read in to the stage data area 22 c .", "Further, the program component 90 for the player character 50 , the program component 91 for the enemy character # 1 and the program component 93 for the enemy character # 2 are read in to the character control code area 22 d. In another stage, the player character 50 , the enemy characters 52 , 53 and a background image 60 F are displayed on the display screen 30 a as shown in FIG. 18 .", "At a time when the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 19 .", "More specifically, a graphic data 65 F for the background image 60 F is read in to the stage data area 22 c .", "Further, the program component 90 for the player character 50 , the program component 92 for the enemy character # 2 and the program component 93 for the enemy character # 3 are read in to the character control code area 22 d. In another stage, as shown in FIG. 20, the player character 50 , the enemy characters 51 through 53 and a background image 60 G are displayed on the display screen 30 a .", "At a time when the video game on this stage is started, the content of the RAM 22 is updated to the one shown in FIG. 21 .", "More specifically, a graphic data 65 G for the background image 60 G is read in to the stage data area 22 c .", "Further, the program component 90 for the player character 50 , the program component 91 for the enemy character # 1 , the program component 92 for the enemy character # 2 and the program component 93 for the enemy character # 3 are read in to the character control code area 22 d. On the CD-ROM 10 , these pieces of information (graphic data, program codes, graphic codes, etc.) which are to be read out and stored in to the RAM 22 under the control of the main program are recorded in the configurations as shown in FIGS. 22, 23 .", "More specifically, the entire recording area on the CD-ROM 10 is divided into two program recording areas 10 a , 10 c and one animation data recording area 10 b as shown in FIG. 22 .", "The animation data recording area 10 b is equivalent to the recording area 100 a in the CD-ROM 100 shown in FIG. 1 .", "Animation data recording area 10 b is stored with movie data in the JPEG format or the MPEG format used at a time when the video game starts, and several movie data each used at a time when a specific event is occurred during an execution of a game, and the likes.", "Whole of the program recording areas 10 a , 10 c is equivalent to whole of the recording area 100 b and the recording area 100 c in the CD-ROM 100 .", "In the program recording area 10 c at the inner radius side on the CD-ROM 10 , the main program and the code table are recorded.", "In the program recording area 10 a at the outer radius side, the various kinds of information (that is, the graphic data for the background image, the program components, and the likes) that are to be read in to the RAM 22 under the control of the main program are recorded.", "In the program recording area 10 a , the plural program components are recorded consecutively.", "In this area where the program components are recorded (hereinafter, referred as to the component recording area) , the program components regarding the characters that may be displayed simultaneously are recorded in the proximity recording locations.", "For example, the above described player character 50 and the enemy characters 51 through 53 (the enemy characters # 1 through # 3 ) may be displayed simultaneously.", "Accordingly, the program components regarding these characters are, as schematically shown in FIG. 23, contiguonsly recorded in the component recording area 29 within the program recording area 10 a. Further, the CD-ROM 10 contains the above mentioned various kinds of information (the program, data, codes) as one file.", "Therefore, the code table read out from the CD-ROM 10 and written into RAM 22 is used for reading out the respective information from the CD-ROM 10 .", "Concretely, as schematically shown in FIG. 24, the code table 95 holds starting position information 96 of 4 bytes and size information 97 of 4 bytes for each of codes # 1 to #N.", "Here, N is a positive integer, and code #X (X is a integer, where 1≦X≦N) is a bulk of information, that is, the program component, the graphic data and the likes, which may be read singly.", "The starting position information 92 for the code #X indicates a starting position of the recording area where the code #X is recorded, and the size information 94 of the code #X indicates the size of the code #X.", "The main program contains instructions for reading out codes from the CD-ROM 10 , each of which includes the code number X corresponding to the code #X.", "More specifically, the main program causes, at a time when a code of the code number X is to be read out from the CD-ROM 10 into RAM 22 , the control unit 21 to obtain the starting position information 92 and the size information 94 corresponding to the code number X from the code table 90 , and to read out the information which is recorded within an area from the position (sector) that is defined by the obtained starting position information 92 , of which size is defined by the obtained size information 94 , on the CD-ROM 10 .", "Furthermore, the main program read into the program area 22 a includes routines which cause the control unit 21 to operate as follows.", "When updating the content of the RAM 22 in to the one shown in FIG. 9, namely, when the program component 90 and 92 are to be stored in the RAM 22 , the control unit 21 first instructs the CD-ROM drive 27 to output data stored in a series of contiguous storage locations which begins at the storage location of the program code 90 for the player character 50 and ends at the storage location of the graphic code 92 for the enemy character # 2 (see FIG. 23 ).", "More Specifically, as schematically shown in FIG. 25, the control unit 21 instructs the CD-ROM drive 27 to output the program components 90 , 91 , and 92 by issuing a instruction including a start address of the program component 90 and the size information indicating the total size of these three program components 90 , 91 and 92 .", "Then, the control unit 21 stores the program component 90 outputted from the CD-ROM drive 27 into the memory area on the RAM 22 , which begins at the address “0015 0000H.”", "Thereafter, the control unit 21 discards the program components 91 outputted from the CD-ROM drive 27 after the program component 90 , without processing the data, and store the program component 92 outputted from the CD-ROM drive 27 after the program component 91 into the memory area on the RAM 22 , which begins at the address “0017 0000H.”", "When updating the contents of the RAM 22 into the one shown in FIG. 12, the control unit 21 instructs the CD-ROM drive 27 to output data stored in a series of contiguous storage locations which begins at the storage location of the program code 90 for the player character, and ends at the storage location of the graphic code 93 for the enemy character # 3 .", "More specifically, the control unit 21 instructs the CD-ROM drive 27 to output four program components 90 trough 93 by issuing a instruction including a start address of the program component 90 and the size information indicating the total size of these program components 90 through 93 .", "Then, the control unit 21 stores the program component 90 outputted from the CD-ROM drive 27 into the RAM 22 .", "Thereafter, the control unit 21 discards the program components 91 and 92 outputted from the CD-ROM drive 27 after the program component 90 , and stores the program component 93 outputted from the CD-ROM drive 27 after the program component 92 in the RAM 22 .", "When updating the content of the RAM 22 into the one shown in FIG. 17 or FIG. 19, the control unit 21 also executes a similar procedure.", "More specifically, the control unit 21 instructs the CD-ROM drive 27 to output data which includes one or more unnecessary program components (that is, the program component 92 in FIG. 17 or the program component 91 in FIG. 9) along with plural necessary program components and which is stored at a series of contiguous storage locations on the CD-ROM 10 .", "Then, the control unit 21 stores only the necessary program components included in the output of the CD-ROM drive 27 into the RAM 22 .", "When updating the content of the RAM 22 into the one shown in FIG. 5, 15 or 21 , namely, when starting a stage of video game which needs some program components record at a series of contiguous storage locations on the CD-ROM 10 , the control unit 21 instructs the CD-ROM drive 27 to output data which consists of the necessary program components, and then stores all the program components outputted from the CD-ROM drive 27 into the RAM 22 .", "As described in detail above, the CD-ROM 10 is configured such that plural program components are recorded in one recording area (that is, contiguous storage locations).", "And the main program recorded in the CD-ROM 10 includes plural routines each for executing a load process, which consists of a process making the CD-ROM drive 27 outputs several program components with one seek action and a process to store some of program component among the program components outputted from the CD-ROM drive 27 in the RAM 22 .", "Consequently, the information processing apparatus 20 set with this CD-ROM 10 operates without making the CD-ROM drive 27 to perform uselessly, and therefore the information processing apparatus 20 can operate at faster speed than the apparatus set with the CD-ROM 100 shown in FIG. 1 .", "The CD-ROM 10 of the embodiment may be varied.", "For example, through the above mentioned CD-ROM 10 is such that the program components are recorded in the storage areas at the outer radius side on the disk, it is desirable to produce the CD-ROM such that the component recording area exists at the inner radius side on the disk when it is designed to be set in the CD-ROM drive in which an access to the data recorded at the inner radius side on the disk can be performed at fast speed.", "It may be arranged such that the program codes and the graphic codes, which constitute the program component, are to be written into areas separated each other, rather than into consecutive areas on the RAM 22 .", "In other words, the storage area for use in the program codes and the storage area for use in the graphic codes may be prepared on the RAM 22 , separately.", "Further, the above mentioned technology may be applied to a recording medium other than the CD-ROM (for example, a DVD or a hard disk).", "The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.", "The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein." ]
FIELD OF THE INVENTION [0001] The present invention relates to braking systems and, more particularly, to a brake pedal apparatus for inhibiting and/or preventing items from becoming lodged under the pedal. BACKGROUND OF THE INVENTION [0002] In recent years, little improvement has been undertaken to provide a pedal apparatus that would protect a potentially dangerous area beneath a moving pedal, such as a brake or clutch pedal. Many recent deaths have been blamed on objects becoming lodged beneath the brake pedal in both commercial and personal vehicles. See, for example, “Coffee mug jammed brakes”, New York Times, Jun. 1, 2004 article. To this day, current pedal assembly designs do not offer any protection to the potentially dangerous area that resides beneath the pedals. The direction of many recent inventions target the structural design in keeping the brake pedal from seizing or immobilizing during a vehicular accident. See, for example, U.S. Pat. No. 5,632,184. Attempts to replace the mechanics of a brake system and incorporate electronics have also been made. See, for example, U.S. Pat. No. 6,033,039. Improvements have also be made to redesign the area around the pedal assembly to increase the functionality of existing pedal assemblies, as well as configuring the assemblies for easy installation. See, for example, U.S. Pat. No. 5,829,317. [0003] As is apparent from the above discussion, much of the work that has occurred in recent years to pedal designs has not been directed to preventing items from becoming lodged underneath the pedal. A need, therefore, exists for an improved pedal design that inhibits such dangerous occurrences. SUMMARY OF THE INVENTION [0004] The present invention is directed to a pedal safety apparatus for incorporation into a conventional pedal assembly. It is a further object of the present invention to provide a pedal apparatus that will protect the potentially dangerous zone beneath a pedal assembly. [0005] The utility of the pedal safety apparatus will serve to restrict objects from becoming lodged between a pedal and the floorings beneath the pedal. The apparatus is designed to not cause any excess or additional resistance when attempting to compress the pedal. The apparatus preferably has no mechanically moving parts. Due to the unreliability and cost factor, the apparatus will not utilize any electronics. It is designed to serve the primary purpose of inhibiting objects from becoming lodged beneath a moving pedal, by creating a barrier, so as to make this potentially dangerous area inaccessible. [0006] The foregoing and other features and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments thereof, as illustrated in the accompanying figures. As will be realized, the invention is capable of modifications in various respects, all without departing from the scope of the invention. Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not as restrictive. BRIEF DESCRIPTION OF THE DRAWINGS [0007] For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown. The drawings are not necessarily to scale, emphasis instead being placed on illustrating the principles of the present invention. [0008] FIG. 1 is a front view of one embodiment of the present invention showing the pedal safety apparatus in an uncompressed state; [0009] FIG. 2 is a side view of the pedal safety apparatus of FIG. 1 ; [0010] FIG. 3 is an isometric view of the pedal safety apparatus of FIG. 1 installed on a pedal assembly; [0011] FIG. 4 is a side view of a pedal assembly with the pedal safety apparatus installed and in its uncompressed state; [0012] FIG. 5 is a side view of the pedal assembly of FIG. 4 illustrating the pedal safety apparatus in its compressed state; and [0013] FIG. 6 is a side view of the pedal assembly illustrating the movement of the pedal during operation. DETAILED DESCRIPTION OF THE INVENTION [0014] To describe the present invention more in detail, an embodiment of the present invention will be described below with references made to the drawings below. Referring to FIGS. 1-6 , a pedal safety apparatus according to the present invention is illustrated and designed to operate when used in collaboration with any device, machine or vehicle that incorporates a pedal assembly. [0015] The pedal safety apparatus includes a collapsible boot 1 , preferably made from a strong, durable, flexible/resilient, rubber-like or a breathable material. Those skilled in the art would readily appreciate that various other materials can be used in the present invention in place of rubber. The boot 1 is preferably formed with circumferential ribs or pleats similar in look to a bellows. The pleats permitting controlled compression of the boot. The pedal safety apparatus' boot 1 is securely adhered or attached to an upper mounting bracket or directly to a conventional pedal 6 . Preferably the attachment is provided by attaching an adhesion area 5 to the bottom surface of the pedal 6 through use of an adhesive. Other forms of attachment may be used. For example, a VELCRO hook and loop type fastener may be used to releasably attach the boot 1 to the pedal 6 . (VELCRO is a trademark of Velcro, Inc.) The boot 1 may alternatively be fastened to the pedal 6 using any conventional fastener, such as a screw. [0016] The pedal safety apparatus' boot 1 is securely attached to a lower mounting bracket or base 2 . The base 2 includes air vents 3 . As will become apparent below, the vents 3 allow for proper venting of fluids, such as gasses, from within the boot 1 in order to ensure that no excess resistance is caused when compression of the pedal 6 and its support arm 7 is performed. While the illustrated embodiment includes air vents 3 in the base 2 , it is also contemplated that the boot 1 could be made from a breathable material or include vents so as to permit venting of air from the boot. [0017] The incorporation of a flexible boot 1 is intended to provide a protective shield without interfering with the normal operation of a pedal assembly or changing a user's driving habits. The base 2 is securely attached to the floor 11 or flooring below the pedal 6 . Preferably the attachment is provided by attaching an adhesion area 4 to the floor 11 through use of an adhesive. Other forms of attachment may be used. For example, a VELCRO-type hook and eye fastener may be used to releasably attach the base 2 to the floor 11 . The base 2 may alternatively be fastened to the floor 11 with conventional fasteners, such as nut and bolt combination or screws. [0018] It is also contemplated that the pedal safety apparatus of the present invention can be formed as part of the conventional pedal assembly. For example, brackets may be formed on the bottom of the pedal 6 onto which the boot 1 is clipped or snapped, The boot 1 of the present invention can be attached to the pedal 6 and/or the pedal support arm 7 of the device, machine or vehicle or the boot 1 can be molded to fit around the pedal 6 so as to essentially form one unit. [0019] When reference is made to the term compression with respect to the pedal, it is referring to the actuation or depression of the pedal 6 towards the floor of the device, machine or vehicle, whether the movement is a pivoting of the pedal support arm 7 about its mounting point to the vehicle or a vertical downward motion of the pedal itself to the floor caused by the application of pressure to the pedal 6 . When reference is made to the pedal assembly, it refers to the combination of the pedal 6 and the pedal support arm 7 . [0020] The purpose that the present invention will serve is to protect the potentially hazardous area beneath the pedal assembly. This area includes any region wherein an object could become lodged or stuck between a pedal and the flooring 11 beneath. The present invention will perform this task by inhibiting access to the vacant space between the pedal 6 and the floor 11 . [0021] FIG. 1 illustrates a front view of the pedal safety apparatus. It presents a detailed view of the boot 1 , base 2 , air vents 3 , upper mounting bracket/attachment area 5 , lower attachment area 4 , pedal 6 and the pedal support arm 7 . This view is an example of an extended pedal before compression of the pedal has taken place. The pedal safety apparatus is preferably sized and shaped to extend or occupy the width and length of the area beneath the pedal 6 . The operational area of the present invention includes any dimensions beneath the operational path of the pedal 6 from a decompressed state, to a fully compressed state. [0022] FIG. 2 illustrates a left side view of the pedal safety apparatus attached to the pedal assembly. It illustrates a detailed view of the boot 1 , base 2 , air vents 3 , upper mounting bracket/attachment area 5 , lower attachment area 4 , pedal 6 and the pedal support arm 7 . This view presents a better understanding of the vulnerable area that lies beneath the pedal assembly and how effortlessly a foreign object can become wedged within this potentially hazardous area. [0023] FIG. 3 is a perspective view of the apparatus. This view illustrates the boot 1 , base 2 , air vents 3 , lower attachment area 4 , pedal 6 and the pedal support arm 7 . This view better demonstrates the coverage that the present invention is intended to provide. It illustrates protection throughout the complete operational area of the present invention including any dimensions beneath the operational path of the pedal 6 from a decompressed state, to a fully compressed state incorporating the length and width of the pedal 6 when either in a decompressed or compressed state. [0024] FIG. 4 is a side view of the pedal safety apparatus as it is intended for use in a vehicle. This view illustrates the pedal assembly in its uncompressed state and, in particular, shows the boot 1 , base 2 , air vents 3 , pedal 6 , pedal support arm 7 and the flooring 11 beneath the pedal assembly. This view entails a vivid image of how the apparatus can be positioned when installed in a conventional pedal assembly design. [0025] FIG. 5 is a side view similar to the view in FIG. 4 illustrating the compressed state of the pedal safety apparatus when the pedal assembly is compressed. It demonstrates a detailed view of the boot 1 , base 2 , air vents 3 , pedal 6 , pedal support arm 7 and the flooring 11 beneath the pedal assembly. This figure also demonstrates an example of how the present invention will appear in compressed state. The air vents 3 permit air to be expelled from within the boot during compression. The figure illustrates how the present invention protects the potentially hazardous area beneath the pedal 6 . [0026] FIG. 6 illustrates the alternate positions of the pedal assembly. The illustration includes alternate uncompressed (in phantom) and compressed states of the base 2 , 2 ′, air vents 3 , 3 ′, floor 11 , 11 ′, pedal 6 , 6 ′ and pedal support arm 7 , 7 ′. This view exemplifies the path that the pedal 6 takes when compressed in a downward motion towards the floor 11 . The shown path outlines the potentially hazardous area that, if not protected by the pedal safety apparatus, could become obstructed by a foreign object. [0027] The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.
A pedal safety apparatus attached to a pedal assembly in a vehicle for restricting objects from becoming lodged between the pedal and the floor. The safety apparatus includes an assembly bracket attached to the floor surface for securing the assembly bracket to the floor surface. An upper attachment portion is attached to a bottom surface of the pedal for securing the upper attachment portion to the pedal. A boot is secured to the upper attachment portion and the assembly bracket and is resiliently compressible when the pedal is translated toward the floor.
Briefly describe the main idea outlined in the provided context.
[ "FIELD OF THE INVENTION [0001] The present invention relates to braking systems and, more particularly, to a brake pedal apparatus for inhibiting and/or preventing items from becoming lodged under the pedal.", "BACKGROUND OF THE INVENTION [0002] In recent years, little improvement has been undertaken to provide a pedal apparatus that would protect a potentially dangerous area beneath a moving pedal, such as a brake or clutch pedal.", "Many recent deaths have been blamed on objects becoming lodged beneath the brake pedal in both commercial and personal vehicles.", "See, for example, “Coffee mug jammed brakes”, New York Times, Jun. 1, 2004 article.", "To this day, current pedal assembly designs do not offer any protection to the potentially dangerous area that resides beneath the pedals.", "The direction of many recent inventions target the structural design in keeping the brake pedal from seizing or immobilizing during a vehicular accident.", "See, for example, U.S. Pat. No. 5,632,184.", "Attempts to replace the mechanics of a brake system and incorporate electronics have also been made.", "See, for example, U.S. Pat. No. 6,033,039.", "Improvements have also be made to redesign the area around the pedal assembly to increase the functionality of existing pedal assemblies, as well as configuring the assemblies for easy installation.", "See, for example, U.S. Pat. No. 5,829,317.", "[0003] As is apparent from the above discussion, much of the work that has occurred in recent years to pedal designs has not been directed to preventing items from becoming lodged underneath the pedal.", "A need, therefore, exists for an improved pedal design that inhibits such dangerous occurrences.", "SUMMARY OF THE INVENTION [0004] The present invention is directed to a pedal safety apparatus for incorporation into a conventional pedal assembly.", "It is a further object of the present invention to provide a pedal apparatus that will protect the potentially dangerous zone beneath a pedal assembly.", "[0005] The utility of the pedal safety apparatus will serve to restrict objects from becoming lodged between a pedal and the floorings beneath the pedal.", "The apparatus is designed to not cause any excess or additional resistance when attempting to compress the pedal.", "The apparatus preferably has no mechanically moving parts.", "Due to the unreliability and cost factor, the apparatus will not utilize any electronics.", "It is designed to serve the primary purpose of inhibiting objects from becoming lodged beneath a moving pedal, by creating a barrier, so as to make this potentially dangerous area inaccessible.", "[0006] The foregoing and other features and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments thereof, as illustrated in the accompanying figures.", "As will be realized, the invention is capable of modifications in various respects, all without departing from the scope of the invention.", "Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not as restrictive.", "BRIEF DESCRIPTION OF THE DRAWINGS [0007] For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred;", "it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.", "The drawings are not necessarily to scale, emphasis instead being placed on illustrating the principles of the present invention.", "[0008] FIG. 1 is a front view of one embodiment of the present invention showing the pedal safety apparatus in an uncompressed state;", "[0009] FIG. 2 is a side view of the pedal safety apparatus of FIG. 1 ;", "[0010] FIG. 3 is an isometric view of the pedal safety apparatus of FIG. 1 installed on a pedal assembly;", "[0011] FIG. 4 is a side view of a pedal assembly with the pedal safety apparatus installed and in its uncompressed state;", "[0012] FIG. 5 is a side view of the pedal assembly of FIG. 4 illustrating the pedal safety apparatus in its compressed state;", "and [0013] FIG. 6 is a side view of the pedal assembly illustrating the movement of the pedal during operation.", "DETAILED DESCRIPTION OF THE INVENTION [0014] To describe the present invention more in detail, an embodiment of the present invention will be described below with references made to the drawings below.", "Referring to FIGS. 1-6 , a pedal safety apparatus according to the present invention is illustrated and designed to operate when used in collaboration with any device, machine or vehicle that incorporates a pedal assembly.", "[0015] The pedal safety apparatus includes a collapsible boot 1 , preferably made from a strong, durable, flexible/resilient, rubber-like or a breathable material.", "Those skilled in the art would readily appreciate that various other materials can be used in the present invention in place of rubber.", "The boot 1 is preferably formed with circumferential ribs or pleats similar in look to a bellows.", "The pleats permitting controlled compression of the boot.", "The pedal safety apparatus'", "boot 1 is securely adhered or attached to an upper mounting bracket or directly to a conventional pedal 6 .", "Preferably the attachment is provided by attaching an adhesion area 5 to the bottom surface of the pedal 6 through use of an adhesive.", "Other forms of attachment may be used.", "For example, a VELCRO hook and loop type fastener may be used to releasably attach the boot 1 to the pedal 6 .", "(VELCRO is a trademark of Velcro, Inc.) The boot 1 may alternatively be fastened to the pedal 6 using any conventional fastener, such as a screw.", "[0016] The pedal safety apparatus'", "boot 1 is securely attached to a lower mounting bracket or base 2 .", "The base 2 includes air vents 3 .", "As will become apparent below, the vents 3 allow for proper venting of fluids, such as gasses, from within the boot 1 in order to ensure that no excess resistance is caused when compression of the pedal 6 and its support arm 7 is performed.", "While the illustrated embodiment includes air vents 3 in the base 2 , it is also contemplated that the boot 1 could be made from a breathable material or include vents so as to permit venting of air from the boot.", "[0017] The incorporation of a flexible boot 1 is intended to provide a protective shield without interfering with the normal operation of a pedal assembly or changing a user's driving habits.", "The base 2 is securely attached to the floor 11 or flooring below the pedal 6 .", "Preferably the attachment is provided by attaching an adhesion area 4 to the floor 11 through use of an adhesive.", "Other forms of attachment may be used.", "For example, a VELCRO-type hook and eye fastener may be used to releasably attach the base 2 to the floor 11 .", "The base 2 may alternatively be fastened to the floor 11 with conventional fasteners, such as nut and bolt combination or screws.", "[0018] It is also contemplated that the pedal safety apparatus of the present invention can be formed as part of the conventional pedal assembly.", "For example, brackets may be formed on the bottom of the pedal 6 onto which the boot 1 is clipped or snapped, The boot 1 of the present invention can be attached to the pedal 6 and/or the pedal support arm 7 of the device, machine or vehicle or the boot 1 can be molded to fit around the pedal 6 so as to essentially form one unit.", "[0019] When reference is made to the term compression with respect to the pedal, it is referring to the actuation or depression of the pedal 6 towards the floor of the device, machine or vehicle, whether the movement is a pivoting of the pedal support arm 7 about its mounting point to the vehicle or a vertical downward motion of the pedal itself to the floor caused by the application of pressure to the pedal 6 .", "When reference is made to the pedal assembly, it refers to the combination of the pedal 6 and the pedal support arm 7 .", "[0020] The purpose that the present invention will serve is to protect the potentially hazardous area beneath the pedal assembly.", "This area includes any region wherein an object could become lodged or stuck between a pedal and the flooring 11 beneath.", "The present invention will perform this task by inhibiting access to the vacant space between the pedal 6 and the floor 11 .", "[0021] FIG. 1 illustrates a front view of the pedal safety apparatus.", "It presents a detailed view of the boot 1 , base 2 , air vents 3 , upper mounting bracket/attachment area 5 , lower attachment area 4 , pedal 6 and the pedal support arm 7 .", "This view is an example of an extended pedal before compression of the pedal has taken place.", "The pedal safety apparatus is preferably sized and shaped to extend or occupy the width and length of the area beneath the pedal 6 .", "The operational area of the present invention includes any dimensions beneath the operational path of the pedal 6 from a decompressed state, to a fully compressed state.", "[0022] FIG. 2 illustrates a left side view of the pedal safety apparatus attached to the pedal assembly.", "It illustrates a detailed view of the boot 1 , base 2 , air vents 3 , upper mounting bracket/attachment area 5 , lower attachment area 4 , pedal 6 and the pedal support arm 7 .", "This view presents a better understanding of the vulnerable area that lies beneath the pedal assembly and how effortlessly a foreign object can become wedged within this potentially hazardous area.", "[0023] FIG. 3 is a perspective view of the apparatus.", "This view illustrates the boot 1 , base 2 , air vents 3 , lower attachment area 4 , pedal 6 and the pedal support arm 7 .", "This view better demonstrates the coverage that the present invention is intended to provide.", "It illustrates protection throughout the complete operational area of the present invention including any dimensions beneath the operational path of the pedal 6 from a decompressed state, to a fully compressed state incorporating the length and width of the pedal 6 when either in a decompressed or compressed state.", "[0024] FIG. 4 is a side view of the pedal safety apparatus as it is intended for use in a vehicle.", "This view illustrates the pedal assembly in its uncompressed state and, in particular, shows the boot 1 , base 2 , air vents 3 , pedal 6 , pedal support arm 7 and the flooring 11 beneath the pedal assembly.", "This view entails a vivid image of how the apparatus can be positioned when installed in a conventional pedal assembly design.", "[0025] FIG. 5 is a side view similar to the view in FIG. 4 illustrating the compressed state of the pedal safety apparatus when the pedal assembly is compressed.", "It demonstrates a detailed view of the boot 1 , base 2 , air vents 3 , pedal 6 , pedal support arm 7 and the flooring 11 beneath the pedal assembly.", "This figure also demonstrates an example of how the present invention will appear in compressed state.", "The air vents 3 permit air to be expelled from within the boot during compression.", "The figure illustrates how the present invention protects the potentially hazardous area beneath the pedal 6 .", "[0026] FIG. 6 illustrates the alternate positions of the pedal assembly.", "The illustration includes alternate uncompressed (in phantom) and compressed states of the base 2 , 2 ′, air vents 3 , 3 ′, floor 11 , 11 ′, pedal 6 , 6 ′ and pedal support arm 7 , 7 ′.", "This view exemplifies the path that the pedal 6 takes when compressed in a downward motion towards the floor 11 .", "The shown path outlines the potentially hazardous area that, if not protected by the pedal safety apparatus, could become obstructed by a foreign object.", "[0027] The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention." ]
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates in general to the fields of medicine, pharmacology and biochemistry. More particularly, the invention relates to prodrugs capable of delivering a drug across the blood brain barrier and uses thereof. [0003] 2. Related Art [0004] The delivery a drug to the central nervous system (CNS), e.g., the brain, is a challenging problem in the treatment of CNS disorders. The drug has to be transported across the selective filtering mechanism of the blood brain barrier (BBB) between the plasma and the CNS. In the past, the polar functional groups of drugs to be delivered to the brain have been masked as fat conjugates making the pro-drug more lipophilic. Gamma aminobutyric acid (GABA) that does not cross the blood brain barrier has been rendered active as a CNS drug by lipophilic conjugation (gabapentin; U.S. Pat. No. 4,894,476) and a similar fatty acid conjugation of dopamine is also known (U.S. Pat. Nos. 4,939,174; 6,107,499). Glycinated pro-drugs (e.g., valproic acid-glycine) are known to cross the blood brain barrier utilizing glycine transporters across the blood brain barriers. Rowley et al., J. Med. Chem., 40: 4053, 1997. Although it is well known that glucose transporters are present in the BBB, utilization of these transporters to get a drug across the BBB has not been relied upon to great extent. [0005] Topiramate is an anti-convulsant comprising a sugar sulfarnate which is a fructo-pyranose derivative. Maryanoff et al., J. Med. Chem., 30: 88, 1987; Maryanoffet al., J. Med. Chem., 41: 1315, 1998. [0006] Dopamine conjugated with glucose through a tethering agent has been shown to cross the BBB. Fernandez et al., Carbohydr. Res., 327: 353, 2000. [0007] U.S. Pat. No. 5,977,326 discloses morphine-6-glucuronide compounds and processes for making the same. [0008] U.S. Pat. Nos. 5,827,819 and 6,024,977 disclose biologically active compounds linked to polar lipid carrier molecules to enhance delivery across physiological barriers such as the BBB. [0009] U.S. Pat. No. 6,313,106 discloses phospholipid derivatives of valproic acid for treating epilepsy, migraine, bipolar disorders and pain. [0010] U.S. Pat. No. 5,051,448 discloses ester derivatives of GABA which cross the BBB. [0011] U.S. Pat. No. 5,994,392 discloses anti-psychotic drugs conjugated to fatty acid carriers. [0012] U.S. Pat. Nos. 4,595,695 and 5,162,573 disclose ester derivatives of valproic acid. [0013] Many drugs have been conjugated to sugars for uses other than the treatment of CNS disorders. [0014] U.S. Pat. No. 5,633,357 discloses methods for the synthesis of carboxylic acid glucuronides, e.g., tetrahydrocannabinoid carboxylic acid glucuronides. [0015] U.S. Pat. No. 5,808,111 discloses 1-(D-glucopyranosyl)acitretinamide and 1-(D-glucopyranuronosyl)acitretinamide for cancer treatment. [0016] U.S. Pat. No. 5,599,953 discloses C-glycoside analogs of N-(4-hydroxyphenyl) retinamid-O-glucuronide and N-glycoside analogs of retinoyl β-glucuronide for breast cancer treatment and prevention. [0017] U.S. Pat. No. 6,339,060 discloses the specific targeting of biologically active compounds to specific sites by linking the compound to a microparticle with a linker that is non-specifically or specifically cleaved inside a mammalian phagocytic cell. [0018] U.S. Pat. No. 5,760,072 discloses a paclitaxel prodrug coupled to a cleavable N-(aliphatic or aromatic)-O-glycosyl carbamate spacer group, wherein the prodrug is activated by a hydrolyzing enzyme, an endogenous enzyme or an exogenous enzyme. [0019] U.S. Pat. No. 5,677,286 discloses glycosylated analogs of camptothecin for use as chemotherapeutic agents. [0020] U.S. Pat. No. 4,855,463 discloses water soluble glucuronic acid derivatives of Vitamin A. [0021] U.S. Pat. No. 5,340,803 discloses conjugates of a cytotoxic compound which is a substrate for tyrosinase and glucuronic acid for the treatment of tumor cells which have β-glucuronidase and tyrosinase activity. [0022] U.S. Pat. No. 5,561,119 discloses glycosylated prodrugs and their use with tumor-specific immunoenzymatic conjugates for the treatment of cancer. [0023] U.S. Pat. No. 5,559,235 discloses water soluble derivatives of camptothecin for treatment of cancer. [0024] U.S. Pat. No. 6,043,367 discloses cancer treating conjugates of a glucuronide and a cytotoxic agent joined by an electron-transporting linker. [0025] U.S. Pat. No. 6,218,519 discloses conjugates of an anthracyclinone group with ester, gylcoside or glucuronide structures which are hydrolyzed by the corresponding esterase, glycosidase or glucuronidase for inhibition of tumor cells and bacterial growth. [0026] U.S. Pat. No. 6,166,089 discloses prodrugs which are covalent conjugates of a pharmacologically active compound and an intracellular transporting adjuvant, characterized by the presence of a covalent bond which is scission-sensitive to intracellular enzyme activity, preferably lipase activity. [0027] A large number of drugs and their metabolites are conjugated in the body as part of the elimination pathway. Glucuronic acid is the most frequent partner to the drug in conjugation. Remington's Pharmaceutical Sciences, A. Osol et al. (eds.), pp. 677 (1980). [0028] According to the present invention, by linking a CNS-active drug to a sugar using an amide bond to form a prodrug, the prodrug will utilize glucose transporters present in the BBB to enter the CNS and be activated by endogenous amidases, thus enhancing treatment of CNS diseases and disorders. SUMMARY OF THE INVENTION [0029] The invention relates to compounds that are conjugates of a CNS-active drug linked through an amide bond to a sugar moiety, with or without a linker moiety. In particular, drugs containing an amino group are linked to a carboxyl group on glucuronic acid and drugs containing a carboxyl group are linked to an amino group on glucosamine in order to form the amide bond. The conjugates act as prodrugs which are able to cross the BBB by utilizing glucose transporters and enter the CNS where the drugs are activated through enzymatic removal of the sugar moiety by endogenous amidases. [0030] The invention also relates to a method for the treatment or amelioration of CNS diseases, disorders or conditions. [0031] The invention also relates to pharmaceutical compositions comprising the compounds of the invention and a pharmaceutically acceptable carrier. DETAILED DESCRIPTION OF THE INVENTION [0000] CNS-Active Drugs [0032] CNS-active drugs are biologically active compounds which exert a useful effect on the CNS when administered to an animal. CNS-active drugs include compounds that are effective for the treatment, amelioration or prevention of CNS diseases, disorders or conditions. These diseases, disorders or conditions encompass neurological and psychiatric disorders, including but not limited to, Alzheimer's disease, Parkinson's disease, Huntington's disease, seizures/epilepsy, Tourette Syndrome, attention deficit hyperactivity disorder, headache, migraine, stroke, trigeminal neuralgia, depression, sleep disorders and trauma. Also included are compounds which effect the CNS in desirable ways that are not related to diseases or disorders, e.g., for appetite suppression. Examples of such CNS-active drugs include, but are not limited to, dopamine, valproic acid, GABA, tacrine, phenyloin, carbamazapine, phenobarbital, primidone, clonazapam, felbamate, topiramate, tiagibine, methylphenidate, amphetamine, dextroamphetamine, methamphetamine, pemoline, desipramine, nortriptyline, bupropion, clonidine, guanfacine, pimozide, sumatriptan, zolmitriptan, rizatriptan, baclofen, levodopa, carbidopa, ropinirole, bromocriptine, pergolide, pramipexole carbamazepine, lainotrigine, levetiracetam zonisamide, galantamine, serotonin, melatonin, sitalin, fluoxetine and amantadine. [0000] Sugar Residues [0033] Sugar residues that are useful in the practice of the present invention include glucosamine, glucuronic acid, hyalobiuronic acid and hyaluronic acid. Other sugar residues that may be used in the practice of the invention include derivatives of glucosamine and glucuronic acid and their mono fluoro derivatives. Preferably, endogenous anidases will recognize and cleave the sugar derivative-drug bond, thus releasing the drug. The sugar residues may have free hydroxy groups, or the hydroxy groups may be acylated, e.g. with a group R 1 —(C═O)—, wherein R 1 is hydrogen, C 1-6 alkyl, C 6-10 substituted or unsubstituted aryl or C 7-16 aralkyl. Preferably, the acyl groups are acetyl or propionyl. Other preferred R 1 groups are phenyl, nitrophenyl, halophenyl, lower alkyl substituted phenyl, lower alkoxy substituted phenyl and the like or benzyl, lower alkoxy substituted benzyl and the like. [0034] The sugar residues may be fully or partially acylated or completely deacylated. The completely or partially acylated glycoside is useful as a defined intermediate for the synthesis of the deacylated material. Useful protecting groups include, but are not limited to, acetyl, benzoyl, nicotinoyl, benzyl, methyl and phenyl. [0035] The compounds of the invention may be in the form of an acid/amine addition salt by treatment with an inorganic or organic acid/base. [0000] Methods of Making the Compounds of the Invention [0036] CNS-active drugs may be linked to a sugar moiety either directly or with the use of a linker moiety. For direct linkage, drugs containing an amino group are linked to a carboxyl group on a sugar such as glucuronic acid and drugs containing a carboxyl group are linked to an amino group on a sugar such as glucosamine in order to form the amide bond. When a linker moiety is used, the CNS-active drug and the sugar moiety are linked through a linker moiety such that an amide bond is formed between the drug and the linker moiety and/or between the sugar and the linker moiety. In one embodiment of the invention, the linker moiety is an alkylene dicarboxylic acid, e.g., malonic acid, succinic acid, glutaric acid, adipic acid or the like. According to the present invention, when the CNS-active drug is dopamine, the dopamine is directly linked to the sugar moiety. [0037] Glucuronate/drug conjugates may be prepared by condensing protected glucuronic acid together with a drug containing an amino group. Similarly, protected glucosamine may be conjugated with a drug containing a carboxyl group and deprotected. [0038] In one particular embodiment, protected D-glucosylamine may be prepared for amide formation with carboxylic acid as shown in Scheme 1. [0039] In another embodiment, protected D-glucuronoyl chloride may be prepared for amide formation with an amine as shown in Scheme 2. [0040] Similarly, N-pthalimidobutyroyl-D-glucosamide may be prepared as shown in Scheme 3. [0041] The preparation of various conjugates of the present invention using the protected sugars shown above are depicted below. EXPERIMENTAL [0000] Synthesis of N-β-methoxybenzylidene)-D-glucosamine [0042] D-glucosamine hydrochloride (215 g; 1 mol) was dissolved in sodium hydroxide solution (1 N; 1 liter) and p-anisaldehyde (122 ml) was added. The solid product obtained was filtered off and dried. The product (250 g) had a melting point of 165° C. in accordance with the literature. [0000] Synthesis of N-(p-methoxy-benzylidene)-1,3,4,6-tetra-O-acetyl-D-glucosamine [0043] The p-anisylidene derivative obtained above (250 g) was dissolved in pyridine (1.25 ml) and acetic anhydride (750 ml) was added slowly at room temperature. The mixture was stirred for 12 hours at room temperature and the clear solution was poured into crushed ice/water mixture (5 liters) and filtered. The precipitate was filtered off and crystallized from methanol (270 g). The product had a melting point of 180-1° C. in accordance with the literature. [0000] Synthesis of 1,3,4,6-tetra-O-acetyl-D-glucosamine Hydrochloride [0044] To a boiling solution of tetra-O-acetyl-p-anisylidene derivative (150 g) obtained as above in acetone (750 ml) was added hydrochloric acid (5 N, 62.5 ml). After stirring the mixture mechanically for 15 minutes, the product was isolated by cooling and adding ether (100 ml) to facilitate complete precipitation. The precipitate was filtered and washed once with ether and dried (100 g; m.p.=230° C. as reported). [0045] Proton NMR spectrum in CDCl 3 : δ 2.2-2.0 (overlapping singlets; 12-H; acetyl); δ 3.0 (t; 1-H; sugar-H); δ 3.8 (broad singlet; 1-H; sugar-H); δ 4.1 (d; 1-H; sugar-H); δ 4.3 (d; 1-H; sugar-H); δ 5.0 (m; 2-H; sugar-H) and δ 5.4 (doublet; 1-H; anomeric-1). [0000] Preparation of 1,2,3,4-tetra-O-acetyl-D-glucuronic Acid: [0046] Glucuronic acid (5 g) was added to a cooled solution of pyridine (15 ml). Acetic anhydride (25 ml) was added and the solution stirred at ambient temperature for 24 hours. The mixture was poured into ice cold water (500 ml). The gummy solid that separated out was decanted and extracted into chloroform (200 ml) and dried over magnesium sulfate. Evaporation of the solvent after charcoal treatment and re-crystallization of the residue gave white crystals from ethanol (8 g). [0047] Proton NMR spectrum in CDCl 3 : δ 6.2 (s; 1-H; C 5 —H); δ 5.0-5.3 (m; 4-H; sugar-H); and δ 2.0-2.2 (overlapping singlets; 12-H; acetyl). [0000] Preparation of 1,2,3,4-tetra-O-acetyl-D-glucuronoyl Chloride [0048] 1,2,3,4-tetra-O-acetyl glucuronic acid (8 g) was dissolved in chloroform (50 ml) and oxalyl chloride (10 ml; excess) was added slowly at 5° C. and allowed to stir and warm to room temperature. After the cessation of gas evolution, the solution was heated gently to reflux and cooled. Solvents and excess oxalyl chloride were removed under low pressure and the product used as is in reacting with tacrine as below. [0000] Preparation of 1′,2′,3′,4′-tetra-O-acetyl-D-glucuronoyl-(1,2,3,4,-tetrahydro)-9-acrinamide (9-[1′,2′,3′,4′-tetra-O-acetyl-D-glucuronamido]-1,2,3,4-tetrahydro Acridine) [0049] A solution of tacrine hydrochloride in pyridine (10 ml) and dimethylformamide (20 ml) at 5° C. was stirred at inert atmosphere. 1,2,3,4-tetra-O-acetyl-D-glucuronoyl chloride (8 g; excess) was added and stirred at room temperature for 12 hours. The mixture was poured into water (200 ml) containing saturated sodium bicarbonate (50 ml). The product was extracted into ethyl acetate (3 times 250 ml) and the combined organic portion was washed well to remove pyridine and dried over magnesium sulfate. The product was separated from unreacted starting materials by column chromatography on silica gel using ethyl acetate-methanol mixtures. The purification afforded white crystals of titled compound (3.2 g; re-crystallized from acetone). [0050] Proton NMR spectrum in CD 3 OD: δ 7.5-8.1 (multiplets; 4-H; aromatic-H); δ 5.9 (broad singlet; C 5 —H); δ 3.6-5.3 (multiplets; sugar-H; 4-H); and δ 1.65-2.5 (multiplets; CH 2 ; 8-H and 12-H from acetate). [0000] Preparation of 4-Phthalimidobutanoic Acid [0051] 4-Aminobutyric acid (GABA; 103 g; 1 mol) was charged into a 2 liter reactor equipped with a mechanical stirrer and phthalic anhydride (148 g; 1 mol) and glacial acetic acid (250 ml) were charged. The contents were heated to reflux and stirred for 2.5 hours and cooled to room temperature and stirred. Water (1.5 L) was added and the mixture stirred and cooled to 5° C. After 1 hour at 5° C., the slurry was filtered and the cake was washed with water (500 ml). The product was air dried and it afforded 175 g of white powder. [0000] Preparation of 3-Phthalimidopropanoic Acid [0052] In a similar fashion 3-aminopropanoic acid was converted to the titled compound as a white crystalline powder in 78% yield. [0053] Proton NMR spectrum in CDCl 3 : δ 1.3 (broad singlet; amine-H; 2-H); a (2.7; triplet; CH 2 ; 2H); δ (3.9; triplet; N—CH 2 ; 2H) and δ (7.7-7.9; doublet; aromatic-H; 4H). [0000] Preparation of N-phthalimidobutanoyl Chloride [0054] In a well ventilated fume-hood N-phthalimidobutyric acid (23.3 g) was added to a solution of toluene (100 ml) containing thionyl chloride (9.0 ml) and dimethylformamide (0.5 ml). The mixture was heated to 45-50° C. and maintained till the gas evolution ceased. The mixture was stirred and heated for a period of 1 hour more. Toluene was removed in a rotary evaporator below 50° C. The resulting paste was redissolved in dichloromethane (50 ml) and evaporated to remove trace amounts of thionyl chloride. The resulting product was connected to a high vacuum pump and used as such in the next step. It was a low melting solid. [0000] Preparation of N-Phthalimidobutanoyl-1,3,4,6-tetra-O-acetyl-2-glucosamide [0055] In a 50 ml round bottomed flask, thionyl chloride (0.93 ml; 8.57 mmol) were added to a solution of 4-N-phthalimidobutyric acid (2 g; 8.58 mmol) in 40 ml toluene and a few drops of DMF. The reaction mixture was allowed to stir for 3.5 hours at room temperature. The product was isolated as a solid after removing toluene at 45-50° C. by rotary evaporation and toluene (20 ml) was added again and evaporated to remove trace amounts of thionyl chloride. [0056] To a stirred solution of 1,3,4,6-tetra-O-acetylglucose (4.47 g; 12.9 mmol) in tetrahydrofuran (60 ml) were added to a solution of N-phthalimidobutanoyl chloride (2.25 g; 8.58 mmol) in tetrahydrofuran (20 ml) followed by pyridine (2 ml). The resulting solution was stirred at room temperature for 4 hours. The product was quenched with saturated sodium bicarbonate solution (150 ml). The desired compound was extracted with dichloromethane (3 times 100 ml) and dried over magnesium sulfate. The crude product was isolated after evaporation and thin layer chromatography of the product (using 1:19 methanol:dichloromethane mixture) showed no signs of starting material. The desired glucosamide was purified by acetone crystallization to afford 4.48 g of white crystals in 92.8% yield. [0057] Proton NMR spectrum in CDCl 3 (CD 3 OD mixture): δ 7.7-7.8 (two singlets; Ar—H; 4H); δ 6.1 (d; 1H; sugar-H); δ 5.8 (d; 1-H; sugar-H); δ 5.1-5.3 (two overlapping triplets; 2-H; sugar-H) δ 3.6-4.3 (multiplets; 6-H; sugar-H and N—CH 2 ); and δ 1.9-2.2 (multiplet and overlapping singlets; 16-H; acetyl and 2×CH 2 ). [0000] Preparation of 2-(n-propyl)-pentanoyl-1′,3′,4′,6′-tetra-O-acetyl-2′-glucosamide (valproyl-2-glucosamide) [0058] To a solution of valproic acid (2.21 ml; 15.35 mmol) in chloroform (10 m) was added thionyl chloride (2.2 ml; 15.3 mmol). The reaction mixture was allowed to stir for 2 hours at room temperature until the gas evolution ceased. The acid chloride was isolated by distilling off chloroform and excess thionyl chloride. Chloroform (20 ml) was added and distilled to remove further traces of thionyl chloride. Dichloromethane (10 ml) was added to the residual acid chloride and used as such as below. [0059] To a cooled solution of N-methyl morpholine (6 ml) and tetrahydrofuran (60 ml) was added 1,3,4,6,-tetra-O-acetyl-D-glucosamine (3.96 g; 11.5 mmol). To this stirred mixture was added the acid chloride in dichloromethane from above. The mixture was stirred for 14 hours at room temperature. The product was isolated after pouring into saturated sodium bicarbonate (150 ml) and extracting with dichloromethane (3 times 100 ml). The organic portion was dried over magnesium sulfate and evaporated. A solid product was obtained. Thin layer chromatographic examination showed the absence of tetra-O-acetyl glucosamine. The solid product was re-dissolved in chloroform and crystallized from ether to a white solid (3 g; 60% isolated yield). [0060] Proton NMR spectrum in CDCl 3 : δ 0.8-1.5 (multiplet; 14H; aliphatic-H); δ 2.0-2.2 (overlapping singlets; 12-H; acetyl); δ 3.0 (s; 1-H; sugar-H); δ 3.7 (broad singlet; 1-H; sugar-H); δ 4.1 (d; 1-H; sugar-H); δ 4.3 (m; 1-H; sugar-H); δ 5.0 (m; 2-H; sugar-H) and δ 5.4 (d; 1-H; anomeric hydrogen). [0000] N-phthalimido-3-hydroxytyramine (N-phthalimido dopamine): [0061] To a stirred suspension of acetic acid (25 ml) and dopamine hydrochloride (5 g) was added pyridine (20 ml) and phthalic anhydride (4.2 g). The mixture was stirred and heated to reflux for 1 hour and cooled, then poured into water (200 ml) and filtered. The precipitate was washed twice with saturated sodium bicarbonate solution (20 ml) and water (20 ml). The dried gelatinous yellow solid (3.5 g) was used as is for the next step. [0062] Proton NMR spectrum in CDCl 3 : δ 2.6 (broad singlet; 2-H; benzylic-H); δ 3.7 (broad singlet; 2-H; N—CH 2 ); δ 6.4-6.6 (two weakly split singlets; 3-H; aromatic-H from catechol); and δ 7.5-7.7 (two singlets; 4-H; aromatic-H from phthalimide). [0000] Glucosylation of N-phthalimido-3-hydroxy tyramine (N-phthalmido Dopamine) [0063] To a stirred suspension of N-phthalimido-3-hydroxy tyramine (3 g) in chloroform (35 ml) and acetonitrile (10 m) was added molecular sieves (4° A; 10 g) and stirred at 5° C. under argon. After 30 minutes, boron trifluoride-etherate (1.2 m) was added and the lightly colored solution was stirred for 5 minutes and tetra-O-benzyl glucopyranose (6 g) was added in chloroform (10 ml) in one lot. The mixture stirred at room temperature to a clear lightly purple solution during 1 hour. The mixture was stirred for a further period of 12 hours at room temperature and extracted with chloroform (250 ml), washed with saturated sodium bicarbonate (150 ml) followed by water (100 ml) and dried over magnesium sulfate. Upon evaporation and silica gel column chromatography eluting with dichloromethane and methanol mixtures, the products were separated. Two major products were obtained which are isomeric glucosides. [0064] The isomeric mixtures were separated by column chromatography on silica gel using dichloromethane, methanol and ethylacetate mixtures. The proton NMR spectra of the isomeric mixtures were identical due to the complexity of the benzyl protecting groups in the sugar region. [0065] Proton NMR spectrum in CDCl 3 : δ 2.8 (multiplet, 2-H, dopamine-CH 2 ); δ 3.3-5.2 (complex; 17-H; benzylic-CH 2 , sugar-H); δ 6.9-7.7 (complex; 23-H; Ar—H). [0000] Methods of Use and Formulation [0066] Particularly preferred routes of administration of the compounds of the present invention are per os, such as elixirs, tablets and capsules, as exemplified below, and by i.v. administration. [0067] More generally, the compounds of the present invention can be administered in any appropriate pharmaceutically acceptable carrier for oral administration since the compounds are biologically active upon oral administration. The compounds of the invention may also be administered in any appropriate pharmaceutical carrier for parenteral, intramuscular, transdermal, intranasal, buccal or inhalation administration. They can be administered by any means that treat or ameliorate the conditions and diseases described herein. [0068] The dosage administered will depend on the age, health and weight of the recipient, kind of concurrent treatment, if any, frequency of treatment and the nature of the effect desired. An exemplary systemic daily dosage is about 0.1 mg to about 500 mg. Normally, from about 1.0 mg to 100 mg daily of the compounds, in one or more dosages per day, is effective to obtain the desired results. One of ordinary skill in the art can determine the optimal dosages and concentrations of active compounds with only routine experimentation. [0069] The compounds can be employed in dosage forms such as tablets and capsules for oral administration. Such dosage forms may comprise well known pharmaceutically acceptable carriers and excipients. In a preferred embodiment, the dosage forms comprise cyclodextran and/or other saccharides and/or sugar alcohols. The compounds may also be formulated in a sterile liquid for formulations such as solutions (e.g. in saline) or suspensions for parenteral use. A lipid vehicle can be used in parenteral administration. [0070] The compounds could also be administered via topical patches, ointments, gels or other transdermal applications. In such compositions, the active ingredient will ordinarily be present in an amount of at least 0.001% by weight based on the total weight of the composition, and not more than 50% by weight. An inert pharmaceutically acceptable carrier is preferable such as 95% ethanol, vegetable oils, propylene glycols, saline buffers, sesame oil, etc. Remington's Pharmaceutical Sciences, 18 th Edition, Geiinaro et al. (eds.), 1990, exemplifies methods of preparing pharmaceutical compositions. [0071] The compounds may also be employed in fast dissolving dosage forms, as described in U.S. Pat. No. 6,316,027, comprising the compounds of the invention, water, gelatin and other ingredients. [0072] The compounds of the invention may be formulated as part of a liposomal composition. [0073] Topical formulations for transdermal, intranasal or inhalation administration may be prepared according to methods well known in the art. For topical administration, the compounds may be applied in any of the conventional pharmaceutical forms. For example, the compounds may be administered as part of a cream, lotion, aerosol, ointment, powder, drops or transdermal patch. Ointments and creams may, for example, be formulated with an aqueous or oily base with the addition of suitable thickening and/or gelling agents. Such bases may include water and/or an oil such as liquid paraffin or a vegetable oil such as peanut oil or castor oil. Thickening agents which may be used include soft paraffin, aluminum stearate, cetostearyl alcohol, polyethylene glycols, wool-fat, hydrogenated lanolin, beeswax and the like. [0074] Lotions may be formulated with an aqueous or oily base and will in general also include one or more of a stabilizing agent, thickening agent, dispersing agent, suspending agent, thickening agent, coloring agent, perfume and the like. [0075] Powders may comprise any suitable powder base including talc, lactose, starch and the like. Drops may comprise an aqueous or non-aqueous base together with one or more dispersing agents, suspending agents, solubilizing agents and the like. [0076] The compositions may further comprise one or more preservatives including bacteriostatic agents including methyl hydroxybenzoate, propyl hydroxybenzoate, chlorocresol, benzalkonium chloride and the like. [0077] The topical compositions comprise from about 0.0001% to 5% by weight, preferably, 0.001 to 0.5% by weight, more preferably, 0.01 to 0.25% by weight of the active compounds. [0078] The compounds of the invention are substantially pure. The phrase “substantially pure” encompasses compounds created by chemical synthesis and/or compounds substantially free of chemicals which may accompany the compounds in the natural state, as evidenced by thin layer chromatography (TLC) or high performance liquid chromatography (HPLC). [0079] Animals which may be treated according to the methods of the present invention include all animals which may benefit therefrom. Included in such animals are humans, veterinary animals and pets, although the invention is not intended to be so limited. [0080] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions without undue experimentation. All patents, patent applications and publications cited herein are incorporated by reference in their entirety.
Disclosed are conjugates comprising a central nervous system-active drug linked through an amide bond to a glucuronic acid or glucosamine moiety, and uses thereof, e.g., for treating or ameliorating central nervous system diseases or disorders.
Summarize the key points of the given document.
[ "BACKGROUND OF THE INVENTION [0001] 1.", "Field of the Invention [0002] The present invention relates in general to the fields of medicine, pharmacology and biochemistry.", "More particularly, the invention relates to prodrugs capable of delivering a drug across the blood brain barrier and uses thereof.", "[0003] 2.", "Related Art [0004] The delivery a drug to the central nervous system (CNS), e.g., the brain, is a challenging problem in the treatment of CNS disorders.", "The drug has to be transported across the selective filtering mechanism of the blood brain barrier (BBB) between the plasma and the CNS.", "In the past, the polar functional groups of drugs to be delivered to the brain have been masked as fat conjugates making the pro-drug more lipophilic.", "Gamma aminobutyric acid (GABA) that does not cross the blood brain barrier has been rendered active as a CNS drug by lipophilic conjugation (gabapentin;", "U.S. Pat. No. 4,894,476) and a similar fatty acid conjugation of dopamine is also known (U.S. Pat. Nos. 4,939,174;", "6,107,499).", "Glycinated pro-drugs (e.g., valproic acid-glycine) are known to cross the blood brain barrier utilizing glycine transporters across the blood brain barriers.", "Rowley et al.", ", J. Med.", "Chem.", ", 40: 4053, 1997.", "Although it is well known that glucose transporters are present in the BBB, utilization of these transporters to get a drug across the BBB has not been relied upon to great extent.", "[0005] Topiramate is an anti-convulsant comprising a sugar sulfarnate which is a fructo-pyranose derivative.", "Maryanoff et al.", ", J. Med.", "Chem.", ", 30: 88, 1987;", "Maryanoffet al.", ", J. Med.", "Chem.", ", 41: 1315, 1998.", "[0006] Dopamine conjugated with glucose through a tethering agent has been shown to cross the BBB.", "Fernandez et al.", ", Carbohydr.", "Res.", ", 327: 353, 2000.", "[0007] U.S. Pat. No. 5,977,326 discloses morphine-6-glucuronide compounds and processes for making the same.", "[0008] U.S. Pat. Nos. 5,827,819 and 6,024,977 disclose biologically active compounds linked to polar lipid carrier molecules to enhance delivery across physiological barriers such as the BBB.", "[0009] U.S. Pat. No. 6,313,106 discloses phospholipid derivatives of valproic acid for treating epilepsy, migraine, bipolar disorders and pain.", "[0010] U.S. Pat. No. 5,051,448 discloses ester derivatives of GABA which cross the BBB.", "[0011] U.S. Pat. No. 5,994,392 discloses anti-psychotic drugs conjugated to fatty acid carriers.", "[0012] U.S. Pat. Nos. 4,595,695 and 5,162,573 disclose ester derivatives of valproic acid.", "[0013] Many drugs have been conjugated to sugars for uses other than the treatment of CNS disorders.", "[0014] U.S. Pat. No. 5,633,357 discloses methods for the synthesis of carboxylic acid glucuronides, e.g., tetrahydrocannabinoid carboxylic acid glucuronides.", "[0015] U.S. Pat. No. 5,808,111 discloses 1-(D-glucopyranosyl)acitretinamide and 1-(D-glucopyranuronosyl)acitretinamide for cancer treatment.", "[0016] U.S. Pat. No. 5,599,953 discloses C-glycoside analogs of N-(4-hydroxyphenyl) retinamid-O-glucuronide and N-glycoside analogs of retinoyl β-glucuronide for breast cancer treatment and prevention.", "[0017] U.S. Pat. No. 6,339,060 discloses the specific targeting of biologically active compounds to specific sites by linking the compound to a microparticle with a linker that is non-specifically or specifically cleaved inside a mammalian phagocytic cell.", "[0018] U.S. Pat. No. 5,760,072 discloses a paclitaxel prodrug coupled to a cleavable N-(aliphatic or aromatic)-O-glycosyl carbamate spacer group, wherein the prodrug is activated by a hydrolyzing enzyme, an endogenous enzyme or an exogenous enzyme.", "[0019] U.S. Pat. No. 5,677,286 discloses glycosylated analogs of camptothecin for use as chemotherapeutic agents.", "[0020] U.S. Pat. No. 4,855,463 discloses water soluble glucuronic acid derivatives of Vitamin A. [0021] U.S. Pat. No. 5,340,803 discloses conjugates of a cytotoxic compound which is a substrate for tyrosinase and glucuronic acid for the treatment of tumor cells which have β-glucuronidase and tyrosinase activity.", "[0022] U.S. Pat. No. 5,561,119 discloses glycosylated prodrugs and their use with tumor-specific immunoenzymatic conjugates for the treatment of cancer.", "[0023] U.S. Pat. No. 5,559,235 discloses water soluble derivatives of camptothecin for treatment of cancer.", "[0024] U.S. Pat. No. 6,043,367 discloses cancer treating conjugates of a glucuronide and a cytotoxic agent joined by an electron-transporting linker.", "[0025] U.S. Pat. No. 6,218,519 discloses conjugates of an anthracyclinone group with ester, gylcoside or glucuronide structures which are hydrolyzed by the corresponding esterase, glycosidase or glucuronidase for inhibition of tumor cells and bacterial growth.", "[0026] U.S. Pat. No. 6,166,089 discloses prodrugs which are covalent conjugates of a pharmacologically active compound and an intracellular transporting adjuvant, characterized by the presence of a covalent bond which is scission-sensitive to intracellular enzyme activity, preferably lipase activity.", "[0027] A large number of drugs and their metabolites are conjugated in the body as part of the elimination pathway.", "Glucuronic acid is the most frequent partner to the drug in conjugation.", "Remington's Pharmaceutical Sciences, A. Osol et al.", "(eds.), pp. 677 (1980).", "[0028] According to the present invention, by linking a CNS-active drug to a sugar using an amide bond to form a prodrug, the prodrug will utilize glucose transporters present in the BBB to enter the CNS and be activated by endogenous amidases, thus enhancing treatment of CNS diseases and disorders.", "SUMMARY OF THE INVENTION [0029] The invention relates to compounds that are conjugates of a CNS-active drug linked through an amide bond to a sugar moiety, with or without a linker moiety.", "In particular, drugs containing an amino group are linked to a carboxyl group on glucuronic acid and drugs containing a carboxyl group are linked to an amino group on glucosamine in order to form the amide bond.", "The conjugates act as prodrugs which are able to cross the BBB by utilizing glucose transporters and enter the CNS where the drugs are activated through enzymatic removal of the sugar moiety by endogenous amidases.", "[0030] The invention also relates to a method for the treatment or amelioration of CNS diseases, disorders or conditions.", "[0031] The invention also relates to pharmaceutical compositions comprising the compounds of the invention and a pharmaceutically acceptable carrier.", "DETAILED DESCRIPTION OF THE INVENTION [0000] CNS-Active Drugs [0032] CNS-active drugs are biologically active compounds which exert a useful effect on the CNS when administered to an animal.", "CNS-active drugs include compounds that are effective for the treatment, amelioration or prevention of CNS diseases, disorders or conditions.", "These diseases, disorders or conditions encompass neurological and psychiatric disorders, including but not limited to, Alzheimer's disease, Parkinson's disease, Huntington's disease, seizures/epilepsy, Tourette Syndrome, attention deficit hyperactivity disorder, headache, migraine, stroke, trigeminal neuralgia, depression, sleep disorders and trauma.", "Also included are compounds which effect the CNS in desirable ways that are not related to diseases or disorders, e.g., for appetite suppression.", "Examples of such CNS-active drugs include, but are not limited to, dopamine, valproic acid, GABA, tacrine, phenyloin, carbamazapine, phenobarbital, primidone, clonazapam, felbamate, topiramate, tiagibine, methylphenidate, amphetamine, dextroamphetamine, methamphetamine, pemoline, desipramine, nortriptyline, bupropion, clonidine, guanfacine, pimozide, sumatriptan, zolmitriptan, rizatriptan, baclofen, levodopa, carbidopa, ropinirole, bromocriptine, pergolide, pramipexole carbamazepine, lainotrigine, levetiracetam zonisamide, galantamine, serotonin, melatonin, sitalin, fluoxetine and amantadine.", "[0000] Sugar Residues [0033] Sugar residues that are useful in the practice of the present invention include glucosamine, glucuronic acid, hyalobiuronic acid and hyaluronic acid.", "Other sugar residues that may be used in the practice of the invention include derivatives of glucosamine and glucuronic acid and their mono fluoro derivatives.", "Preferably, endogenous anidases will recognize and cleave the sugar derivative-drug bond, thus releasing the drug.", "The sugar residues may have free hydroxy groups, or the hydroxy groups may be acylated, e.g. with a group R 1 —(C═O)—, wherein R 1 is hydrogen, C 1-6 alkyl, C 6-10 substituted or unsubstituted aryl or C 7-16 aralkyl.", "Preferably, the acyl groups are acetyl or propionyl.", "Other preferred R 1 groups are phenyl, nitrophenyl, halophenyl, lower alkyl substituted phenyl, lower alkoxy substituted phenyl and the like or benzyl, lower alkoxy substituted benzyl and the like.", "[0034] The sugar residues may be fully or partially acylated or completely deacylated.", "The completely or partially acylated glycoside is useful as a defined intermediate for the synthesis of the deacylated material.", "Useful protecting groups include, but are not limited to, acetyl, benzoyl, nicotinoyl, benzyl, methyl and phenyl.", "[0035] The compounds of the invention may be in the form of an acid/amine addition salt by treatment with an inorganic or organic acid/base.", "[0000] Methods of Making the Compounds of the Invention [0036] CNS-active drugs may be linked to a sugar moiety either directly or with the use of a linker moiety.", "For direct linkage, drugs containing an amino group are linked to a carboxyl group on a sugar such as glucuronic acid and drugs containing a carboxyl group are linked to an amino group on a sugar such as glucosamine in order to form the amide bond.", "When a linker moiety is used, the CNS-active drug and the sugar moiety are linked through a linker moiety such that an amide bond is formed between the drug and the linker moiety and/or between the sugar and the linker moiety.", "In one embodiment of the invention, the linker moiety is an alkylene dicarboxylic acid, e.g., malonic acid, succinic acid, glutaric acid, adipic acid or the like.", "According to the present invention, when the CNS-active drug is dopamine, the dopamine is directly linked to the sugar moiety.", "[0037] Glucuronate/drug conjugates may be prepared by condensing protected glucuronic acid together with a drug containing an amino group.", "Similarly, protected glucosamine may be conjugated with a drug containing a carboxyl group and deprotected.", "[0038] In one particular embodiment, protected D-glucosylamine may be prepared for amide formation with carboxylic acid as shown in Scheme 1.", "[0039] In another embodiment, protected D-glucuronoyl chloride may be prepared for amide formation with an amine as shown in Scheme 2.", "[0040] Similarly, N-pthalimidobutyroyl-D-glucosamide may be prepared as shown in Scheme 3.", "[0041] The preparation of various conjugates of the present invention using the protected sugars shown above are depicted below.", "EXPERIMENTAL [0000] Synthesis of N-β-methoxybenzylidene)-D-glucosamine [0042] D-glucosamine hydrochloride (215 g;", "1 mol) was dissolved in sodium hydroxide solution (1 N;", "1 liter) and p-anisaldehyde (122 ml) was added.", "The solid product obtained was filtered off and dried.", "The product (250 g) had a melting point of 165° C. in accordance with the literature.", "[0000] Synthesis of N-(p-methoxy-benzylidene)-1,3,4,6-tetra-O-acetyl-D-glucosamine [0043] The p-anisylidene derivative obtained above (250 g) was dissolved in pyridine (1.25 ml) and acetic anhydride (750 ml) was added slowly at room temperature.", "The mixture was stirred for 12 hours at room temperature and the clear solution was poured into crushed ice/water mixture (5 liters) and filtered.", "The precipitate was filtered off and crystallized from methanol (270 g).", "The product had a melting point of 180-1° C. in accordance with the literature.", "[0000] Synthesis of 1,3,4,6-tetra-O-acetyl-D-glucosamine Hydrochloride [0044] To a boiling solution of tetra-O-acetyl-p-anisylidene derivative (150 g) obtained as above in acetone (750 ml) was added hydrochloric acid (5 N, 62.5 ml).", "After stirring the mixture mechanically for 15 minutes, the product was isolated by cooling and adding ether (100 ml) to facilitate complete precipitation.", "The precipitate was filtered and washed once with ether and dried (100 g;", "m.p.=230° C. as reported).", "[0045] Proton NMR spectrum in CDCl 3 : δ 2.2-2.0 (overlapping singlets;", "12-H;", "acetyl);", "δ 3.0 (t;", "1-H;", "sugar-H);", "δ 3.8 (broad singlet;", "1-H;", "sugar-H);", "δ 4.1 (d;", "1-H;", "sugar-H);", "δ 4.3 (d;", "1-H;", "sugar-H);", "δ 5.0 (m;", "2-H;", "sugar-H) and δ 5.4 (doublet;", "1-H;", "anomeric-1).", "[0000] Preparation of 1,2,3,4-tetra-O-acetyl-D-glucuronic Acid: [0046] Glucuronic acid (5 g) was added to a cooled solution of pyridine (15 ml).", "Acetic anhydride (25 ml) was added and the solution stirred at ambient temperature for 24 hours.", "The mixture was poured into ice cold water (500 ml).", "The gummy solid that separated out was decanted and extracted into chloroform (200 ml) and dried over magnesium sulfate.", "Evaporation of the solvent after charcoal treatment and re-crystallization of the residue gave white crystals from ethanol (8 g).", "[0047] Proton NMR spectrum in CDCl 3 : δ 6.2 (s;", "1-H;", "C 5 —H);", "δ 5.0-5.3 (m;", "4-H;", "sugar-H);", "and δ 2.0-2.2 (overlapping singlets;", "12-H;", "acetyl).", "[0000] Preparation of 1,2,3,4-tetra-O-acetyl-D-glucuronoyl Chloride [0048] 1,2,3,4-tetra-O-acetyl glucuronic acid (8 g) was dissolved in chloroform (50 ml) and oxalyl chloride (10 ml;", "excess) was added slowly at 5° C. and allowed to stir and warm to room temperature.", "After the cessation of gas evolution, the solution was heated gently to reflux and cooled.", "Solvents and excess oxalyl chloride were removed under low pressure and the product used as is in reacting with tacrine as below.", "[0000] Preparation of 1′,2′,3′,4′-tetra-O-acetyl-D-glucuronoyl-(1,2,3,4,-tetrahydro)-9-acrinamide (9-[1′,2′,3′,4′-tetra-O-acetyl-D-glucuronamido]-1,2,3,4-tetrahydro Acridine) [0049] A solution of tacrine hydrochloride in pyridine (10 ml) and dimethylformamide (20 ml) at 5° C. was stirred at inert atmosphere.", "1,2,3,4-tetra-O-acetyl-D-glucuronoyl chloride (8 g;", "excess) was added and stirred at room temperature for 12 hours.", "The mixture was poured into water (200 ml) containing saturated sodium bicarbonate (50 ml).", "The product was extracted into ethyl acetate (3 times 250 ml) and the combined organic portion was washed well to remove pyridine and dried over magnesium sulfate.", "The product was separated from unreacted starting materials by column chromatography on silica gel using ethyl acetate-methanol mixtures.", "The purification afforded white crystals of titled compound (3.2 g;", "re-crystallized from acetone).", "[0050] Proton NMR spectrum in CD 3 OD: δ 7.5-8.1 (multiplets;", "4-H;", "aromatic-H);", "δ 5.9 (broad singlet;", "C 5 —H);", "δ 3.6-5.3 (multiplets;", "sugar-H;", "4-H);", "and δ 1.65-2.5 (multiplets;", "CH 2 ;", "8-H and 12-H from acetate).", "[0000] Preparation of 4-Phthalimidobutanoic Acid [0051] 4-Aminobutyric acid (GABA;", "103 g;", "1 mol) was charged into a 2 liter reactor equipped with a mechanical stirrer and phthalic anhydride (148 g;", "1 mol) and glacial acetic acid (250 ml) were charged.", "The contents were heated to reflux and stirred for 2.5 hours and cooled to room temperature and stirred.", "Water (1.5 L) was added and the mixture stirred and cooled to 5° C. After 1 hour at 5° C., the slurry was filtered and the cake was washed with water (500 ml).", "The product was air dried and it afforded 175 g of white powder.", "[0000] Preparation of 3-Phthalimidopropanoic Acid [0052] In a similar fashion 3-aminopropanoic acid was converted to the titled compound as a white crystalline powder in 78% yield.", "[0053] Proton NMR spectrum in CDCl 3 : δ 1.3 (broad singlet;", "amine-H;", "2-H);", "a (2.7;", "triplet;", "CH 2 ;", "2H);", "δ (3.9;", "triplet;", "N—CH 2 ;", "2H) and δ (7.7-7.9;", "doublet;", "aromatic-H;", "4H).", "[0000] Preparation of N-phthalimidobutanoyl Chloride [0054] In a well ventilated fume-hood N-phthalimidobutyric acid (23.3 g) was added to a solution of toluene (100 ml) containing thionyl chloride (9.0 ml) and dimethylformamide (0.5 ml).", "The mixture was heated to 45-50° C. and maintained till the gas evolution ceased.", "The mixture was stirred and heated for a period of 1 hour more.", "Toluene was removed in a rotary evaporator below 50° C. The resulting paste was redissolved in dichloromethane (50 ml) and evaporated to remove trace amounts of thionyl chloride.", "The resulting product was connected to a high vacuum pump and used as such in the next step.", "It was a low melting solid.", "[0000] Preparation of N-Phthalimidobutanoyl-1,3,4,6-tetra-O-acetyl-2-glucosamide [0055] In a 50 ml round bottomed flask, thionyl chloride (0.93 ml;", "8.57 mmol) were added to a solution of 4-N-phthalimidobutyric acid (2 g;", "8.58 mmol) in 40 ml toluene and a few drops of DMF.", "The reaction mixture was allowed to stir for 3.5 hours at room temperature.", "The product was isolated as a solid after removing toluene at 45-50° C. by rotary evaporation and toluene (20 ml) was added again and evaporated to remove trace amounts of thionyl chloride.", "[0056] To a stirred solution of 1,3,4,6-tetra-O-acetylglucose (4.47 g;", "12.9 mmol) in tetrahydrofuran (60 ml) were added to a solution of N-phthalimidobutanoyl chloride (2.25 g;", "8.58 mmol) in tetrahydrofuran (20 ml) followed by pyridine (2 ml).", "The resulting solution was stirred at room temperature for 4 hours.", "The product was quenched with saturated sodium bicarbonate solution (150 ml).", "The desired compound was extracted with dichloromethane (3 times 100 ml) and dried over magnesium sulfate.", "The crude product was isolated after evaporation and thin layer chromatography of the product (using 1:19 methanol:dichloromethane mixture) showed no signs of starting material.", "The desired glucosamide was purified by acetone crystallization to afford 4.48 g of white crystals in 92.8% yield.", "[0057] Proton NMR spectrum in CDCl 3 (CD 3 OD mixture): δ 7.7-7.8 (two singlets;", "Ar—H;", "4H);", "δ 6.1 (d;", "1H;", "sugar-H);", "δ 5.8 (d;", "1-H;", "sugar-H);", "δ 5.1-5.3 (two overlapping triplets;", "2-H;", "sugar-H) δ 3.6-4.3 (multiplets;", "6-H;", "sugar-H and N—CH 2 );", "and δ 1.9-2.2 (multiplet and overlapping singlets;", "16-H;", "acetyl and 2×CH 2 ).", "[0000] Preparation of 2-(n-propyl)-pentanoyl-1′,3′,4′,6′-tetra-O-acetyl-2′-glucosamide (valproyl-2-glucosamide) [0058] To a solution of valproic acid (2.21 ml;", "15.35 mmol) in chloroform (10 m) was added thionyl chloride (2.2 ml;", "15.3 mmol).", "The reaction mixture was allowed to stir for 2 hours at room temperature until the gas evolution ceased.", "The acid chloride was isolated by distilling off chloroform and excess thionyl chloride.", "Chloroform (20 ml) was added and distilled to remove further traces of thionyl chloride.", "Dichloromethane (10 ml) was added to the residual acid chloride and used as such as below.", "[0059] To a cooled solution of N-methyl morpholine (6 ml) and tetrahydrofuran (60 ml) was added 1,3,4,6,-tetra-O-acetyl-D-glucosamine (3.96 g;", "11.5 mmol).", "To this stirred mixture was added the acid chloride in dichloromethane from above.", "The mixture was stirred for 14 hours at room temperature.", "The product was isolated after pouring into saturated sodium bicarbonate (150 ml) and extracting with dichloromethane (3 times 100 ml).", "The organic portion was dried over magnesium sulfate and evaporated.", "A solid product was obtained.", "Thin layer chromatographic examination showed the absence of tetra-O-acetyl glucosamine.", "The solid product was re-dissolved in chloroform and crystallized from ether to a white solid (3 g;", "60% isolated yield).", "[0060] Proton NMR spectrum in CDCl 3 : δ 0.8-1.5 (multiplet;", "14H;", "aliphatic-H);", "δ 2.0-2.2 (overlapping singlets;", "12-H;", "acetyl);", "δ 3.0 (s;", "1-H;", "sugar-H);", "δ 3.7 (broad singlet;", "1-H;", "sugar-H);", "δ 4.1 (d;", "1-H;", "sugar-H);", "δ 4.3 (m;", "1-H;", "sugar-H);", "δ 5.0 (m;", "2-H;", "sugar-H) and δ 5.4 (d;", "1-H;", "anomeric hydrogen).", "[0000] N-phthalimido-3-hydroxytyramine (N-phthalimido dopamine): [0061] To a stirred suspension of acetic acid (25 ml) and dopamine hydrochloride (5 g) was added pyridine (20 ml) and phthalic anhydride (4.2 g).", "The mixture was stirred and heated to reflux for 1 hour and cooled, then poured into water (200 ml) and filtered.", "The precipitate was washed twice with saturated sodium bicarbonate solution (20 ml) and water (20 ml).", "The dried gelatinous yellow solid (3.5 g) was used as is for the next step.", "[0062] Proton NMR spectrum in CDCl 3 : δ 2.6 (broad singlet;", "2-H;", "benzylic-H);", "δ 3.7 (broad singlet;", "2-H;", "N—CH 2 );", "δ 6.4-6.6 (two weakly split singlets;", "3-H;", "aromatic-H from catechol);", "and δ 7.5-7.7 (two singlets;", "4-H;", "aromatic-H from phthalimide).", "[0000] Glucosylation of N-phthalimido-3-hydroxy tyramine (N-phthalmido Dopamine) [0063] To a stirred suspension of N-phthalimido-3-hydroxy tyramine (3 g) in chloroform (35 ml) and acetonitrile (10 m) was added molecular sieves (4° A;", "10 g) and stirred at 5° C. under argon.", "After 30 minutes, boron trifluoride-etherate (1.2 m) was added and the lightly colored solution was stirred for 5 minutes and tetra-O-benzyl glucopyranose (6 g) was added in chloroform (10 ml) in one lot.", "The mixture stirred at room temperature to a clear lightly purple solution during 1 hour.", "The mixture was stirred for a further period of 12 hours at room temperature and extracted with chloroform (250 ml), washed with saturated sodium bicarbonate (150 ml) followed by water (100 ml) and dried over magnesium sulfate.", "Upon evaporation and silica gel column chromatography eluting with dichloromethane and methanol mixtures, the products were separated.", "Two major products were obtained which are isomeric glucosides.", "[0064] The isomeric mixtures were separated by column chromatography on silica gel using dichloromethane, methanol and ethylacetate mixtures.", "The proton NMR spectra of the isomeric mixtures were identical due to the complexity of the benzyl protecting groups in the sugar region.", "[0065] Proton NMR spectrum in CDCl 3 : δ 2.8 (multiplet, 2-H, dopamine-CH 2 );", "δ 3.3-5.2 (complex;", "17-H;", "benzylic-CH 2 , sugar-H);", "δ 6.9-7.7 (complex;", "23-H;", "Ar—H).", "[0000] Methods of Use and Formulation [0066] Particularly preferred routes of administration of the compounds of the present invention are per os, such as elixirs, tablets and capsules, as exemplified below, and by i.v. administration.", "[0067] More generally, the compounds of the present invention can be administered in any appropriate pharmaceutically acceptable carrier for oral administration since the compounds are biologically active upon oral administration.", "The compounds of the invention may also be administered in any appropriate pharmaceutical carrier for parenteral, intramuscular, transdermal, intranasal, buccal or inhalation administration.", "They can be administered by any means that treat or ameliorate the conditions and diseases described herein.", "[0068] The dosage administered will depend on the age, health and weight of the recipient, kind of concurrent treatment, if any, frequency of treatment and the nature of the effect desired.", "An exemplary systemic daily dosage is about 0.1 mg to about 500 mg.", "Normally, from about 1.0 mg to 100 mg daily of the compounds, in one or more dosages per day, is effective to obtain the desired results.", "One of ordinary skill in the art can determine the optimal dosages and concentrations of active compounds with only routine experimentation.", "[0069] The compounds can be employed in dosage forms such as tablets and capsules for oral administration.", "Such dosage forms may comprise well known pharmaceutically acceptable carriers and excipients.", "In a preferred embodiment, the dosage forms comprise cyclodextran and/or other saccharides and/or sugar alcohols.", "The compounds may also be formulated in a sterile liquid for formulations such as solutions (e.g. in saline) or suspensions for parenteral use.", "A lipid vehicle can be used in parenteral administration.", "[0070] The compounds could also be administered via topical patches, ointments, gels or other transdermal applications.", "In such compositions, the active ingredient will ordinarily be present in an amount of at least 0.001% by weight based on the total weight of the composition, and not more than 50% by weight.", "An inert pharmaceutically acceptable carrier is preferable such as 95% ethanol, vegetable oils, propylene glycols, saline buffers, sesame oil, etc.", "Remington's Pharmaceutical Sciences, 18 th Edition, Geiinaro et al.", "(eds.), 1990, exemplifies methods of preparing pharmaceutical compositions.", "[0071] The compounds may also be employed in fast dissolving dosage forms, as described in U.S. Pat. No. 6,316,027, comprising the compounds of the invention, water, gelatin and other ingredients.", "[0072] The compounds of the invention may be formulated as part of a liposomal composition.", "[0073] Topical formulations for transdermal, intranasal or inhalation administration may be prepared according to methods well known in the art.", "For topical administration, the compounds may be applied in any of the conventional pharmaceutical forms.", "For example, the compounds may be administered as part of a cream, lotion, aerosol, ointment, powder, drops or transdermal patch.", "Ointments and creams may, for example, be formulated with an aqueous or oily base with the addition of suitable thickening and/or gelling agents.", "Such bases may include water and/or an oil such as liquid paraffin or a vegetable oil such as peanut oil or castor oil.", "Thickening agents which may be used include soft paraffin, aluminum stearate, cetostearyl alcohol, polyethylene glycols, wool-fat, hydrogenated lanolin, beeswax and the like.", "[0074] Lotions may be formulated with an aqueous or oily base and will in general also include one or more of a stabilizing agent, thickening agent, dispersing agent, suspending agent, thickening agent, coloring agent, perfume and the like.", "[0075] Powders may comprise any suitable powder base including talc, lactose, starch and the like.", "Drops may comprise an aqueous or non-aqueous base together with one or more dispersing agents, suspending agents, solubilizing agents and the like.", "[0076] The compositions may further comprise one or more preservatives including bacteriostatic agents including methyl hydroxybenzoate, propyl hydroxybenzoate, chlorocresol, benzalkonium chloride and the like.", "[0077] The topical compositions comprise from about 0.0001% to 5% by weight, preferably, 0.001 to 0.5% by weight, more preferably, 0.01 to 0.25% by weight of the active compounds.", "[0078] The compounds of the invention are substantially pure.", "The phrase “substantially pure”", "encompasses compounds created by chemical synthesis and/or compounds substantially free of chemicals which may accompany the compounds in the natural state, as evidenced by thin layer chromatography (TLC) or high performance liquid chromatography (HPLC).", "[0079] Animals which may be treated according to the methods of the present invention include all animals which may benefit therefrom.", "Included in such animals are humans, veterinary animals and pets, although the invention is not intended to be so limited.", "[0080] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions without undue experimentation.", "All patents, patent applications and publications cited herein are incorporated by reference in their entirety." ]
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to, and the benefit of, co-pending U.S. provisional application entitled “Fragmented Aperture Antennas” having Ser. No. 62/203,316, filed Aug. 10, 2015, which is hereby incorporated by reference in its entirety. BACKGROUND [0002] Originally, fragmented aperture antennas were envisioned as a planar surface with a grid of rectangular regions or pixels that are either conducting or non-conducting. A genetic algorithm (GA) and a computational electromagnetic model were used to determine which pixels should be conducting and which should be non-conducting to form an antenna surface suitable for a given use. BRIEF DESCRIPTION OF THE DRAWINGS [0003] Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. [0004] FIGS. 1 through 4 illustrate examples fragmented aperture antennas in accordance with various embodiments of the present disclosure. [0005] FIGS. 5A through 5D illustrate examples of fragmented aperture antenna designs addressing diagonal touching in accordance with various embodiments of the present disclosure. [0006] FIGS. 6 through 8 illustrate examples fragmented aperture antenna designs that avoid diagonal touching in accordance with various embodiments of the present disclosure. [0007] FIG. 9 illustrates an example of fitness score for a traditional mutation algorithm and an adjacency-based mutation algorithm as a function of generation count in accordance with various embodiments of the present disclosure. [0008] FIG. 10 is a table illustrating a comparison of the traditional mutation algorithm and the adjacency-based mutation algorithm in accordance with various embodiments of the present disclosure. [0009] FIG. 11 illustrates examples of representative aperture designs based upon the arrangements of FIG. 6 in accordance with various embodiments of the present disclosure. [0010] FIGS. 12 and 13 illustrate test results of the representative aperture designs of FIG. 11 in accordance with various embodiments of the present disclosure. [0011] FIG. 14 illustrates examples of representative aperture designs based upon the arrangements of FIG. 7 in accordance with various embodiments of the present disclosure. [0012] FIGS. 15 and 16 illustrate test results of the representative aperture designs of FIG. 14 in accordance with various embodiments of the present disclosure. DETAILED DESCRIPTION [0013] Disclosed herein are various embodiments related to fragmented aperture antennas. Reference will now be made in detail to the description of the embodiments as illustrated in the drawings, wherein like reference numbers indicate like parts throughout the several views. [0014] The physical shape and size of highly pixelated apertures can been optimized using genetic algorithms (GA) and full-wave computational electromagnetic simulation tools (i.e. FDTD) to best meet desired antenna performance specifications (e.g., gain, bandwidth, polarization, pattern, etc.). FIG. 1 shows an example of a fragmented aperture antenna including a grid of rectangular pixels 103 a. Visual inspection of the design shows that the metallic pixels 103 form many connected and disconnected fragments. Hence, the term fragmented aperture antenna has been coined for this class of antennas. The approach illustrated in FIG. 1 has been successfully used to design novel antennas. This concept can be generalized to conducting or non-conducting parallelogram pixels 103 b as shown in FIG. 2 . [0015] However, the original fragmented design approach suffers from two major deficiencies. First, the placement of pixels 103 on a generalized, rectilinear grid leads to the problem of diagonal touching as illustrated in the top right of FIGS. 1 and 2 . Pixels 103 that touch diagonally (i.e., diagonal touching 106 ) lead to poor measurement/model agreement. Second, the convergence in the GA stage of the design process is poor for high pixel count (>>100) apertures. [0016] Diagonal touching 106 is not a problem during the design phase because in the numerical models the diagonally touching 106 of pixels 103 in the antenna are always touching. However, when fabricated using approaches such as printed circuit board etching, the pixels 103 are often disconnected because of over-etching. FIG. 3 illustrates an example of over-etching 109 that can lead to diagonal touches 106 between conducting regions 103 being disconnected. Disconnecting metal pixels 103 that should be connected within an antenna causes problems with the antenna impedance and gain characteristics. [0017] In fact, nearly every fragmented aperture antenna design presented in U.S. Pat. No. 6,323,809 suffers from this issue of diagonal touching. FIG. 4 illustrates examples of diagonal touching 106 in two designs from U.S. Pat. No. 6,323,809. It has been noted that if the pixels 103 have edges parallel to the lattice forming vectors (as in the approaches of FIGS. 1 and 2 ), then the issue of “diagonal touching” 106 will persist. Various approaches will be presented that have been successfully used to mitigate these diagonal touching issues. [0018] Mitigation of Diagonal Touching [0019] One approach utilizes a super-cell approach as illustrated in FIG. 5A . A super-cell 503 is a collection of smaller areas such as, e.g., a 3 by 3 lattice of the smaller pixels or sub elements 506 as shown in FIGS. 5A-5D . To avoid diagonal touching 106 , define the conducting region or pixel 509 as covering the 5 sub-elements 506 that defined a plus sign within the super-cell 503 . Hence, the absence of conducting material in the corners of the super-cell 503 prevents any potential for diagonal touching 106 . This successfully allows antennas to be designed and fabricated with a high probability of good correlation between measured and modeled characteristics of the antenna. In this approach, the electrical currents are constrained to flow in only grid conforming directions, which may limit optimization of the antenna designs. [0020] Another approach includes fabrication of every pixel 103 with an area that is roughly 10% larger than designed, as illustrated in FIG. 5B . Oversizing the pixels 103 ensures diagonal touching 106 by overlapping with diagonally adjacent pixels 103 . This approach was found to lead to a high percentage of good fabricated antennas. However, this approach leads to the antennas having approximately 10-20% more conductor area than originally designed, which can lead to less than desired antenna characteristics in the fabricated antennas. [0021] It is worth noting that fabricating the conducting pixels 103 to be 10% smaller, would guarantee the pixels 103 would never diagonally touch 106 , but this would lead to antennas that never have conducting areas larger than one pixel 103 , which would almost never be any good. Also, this would be contrary to the numerical models used in design where the conducting elements 103 always touch when diagonally adjacent. [0022] Other implementations include a variant of the slightly larger pixel strategy of FIG. 5B , where a small patch 512 of conducting material or metal is placed at the diagonal touching location as shown in FIG. 5C . The small patch 512 can be a square as illustrated in FIG. 5C or other appropriate geometrical shape. Another implementation is illustrated in FIG. 5D , where one of the two open pixel locations adjacent to the diagonal touching 106 is coated with conductive material. A random coin flipping process can be used to decide which of the two non-conducting pixel locations to make conducting to fix the diagonal touch 106 as shown in FIG. 5D . [0023] Various approaches for avoiding diagonal touching 106 by breaking the dependence of element edges and lattice directions implicit in FIGS. 1 and 2 will now be discussed. Three approaches for breaking this dependence are presented which can lead to improved fragmented aperture antennas. [0024] First Approach. In a first approach to improve the fragmented apertures, the location of individual conducting/non-conducting elements can be defined using a second set of directions (or lattice vectors) that are not both parallel with the lattice constants or edges of the conducting regions or pixels 103 as illustrated in FIG. 6 . In the example of FIG. 6 , the antenna comprises a lattice of square or rectangular conducting elements 103 where the lattice includes an X degree skewed lattice such that the adjacent conducting regions 103 are offset from each other based on the skew. Edge vectors E 1 and E 2 define the lattice constants with at least one of the lattice vectors V 1 and/or V 2 not being in parallel with E 1 or E 2 . In FIG. 6 , skewing the lattice vector V 2 has removed the diagonal touching possibility. The skew angle X will be less than 90 degrees, and can be in a range from 75 degrees to 45 degrees, a range from 60 degrees to 45 degrees, or in a range from 70 degrees to 50 degrees. In the examples of FIG. 11 , the skew angle is about 63 degrees. In some implementations, both lattice vectors V 1 and V 2 may be skewed. [0025] Second Approach. In a second approach to improve the fragmented apertures, the shapes of fundamental conducting regions and non-conducting regions can alternate such that the conducting elements 703 diagonally touch in a definite manner as illustrated in FIG. 7 . In the example of FIG. 7 , the shapes of the two regions comprise an octagon and a diamond. Other combinations of geometric shapes can be chosen such that the pair of shapes tessellate the plane. [0026] Third Approach. In a third approach to improve the fragmented apertures, the shape of the fundamental conducting regions and non-conducting regions is chosen such that the single shape tessellates the plane and does not touch diagonally. FIG. 8 shows one example of such a conducting element or pixel 803 , but many other shapes can also be utilized. The shape of the conducting element 803 in FIG. 8 is a skewed-Z that allows the regions to be interleaved in an interdigitated fashion to cover the plane. [0027] Mutation Algorithm to Improve Convergence Rate of Fragmented Apertures [0028] Traditionally, fragmented aperture antennas are designed using evolutionary algorithms like the genetic algorithm of U.S. Pat. No. 6,323,809, which is hereby incorporated by reference in its entirety. One important step in the genetic algorithm is called mutation. In a standard genetic algorithm, mutation is a random process where a small number of genes are changed each generation to help avoid convergence to a suboptimal solution. For a fragmented antenna, mutation makes a few pixels randomly conducting or not in the next population of antennas. Many of these mutations will create only an isolated metal pixel or small hole in metal that will have a very negligible effect on the antenna performance. [0029] A modified mutation algorithm tailored for fragmented aperture antennas can be introduced to help speed up the convergence of the design process when the number of elements/pixels is high. The goal of the new or modified mutation process is to bias mutation to either increase the size of conducting fragments in empty (or non-conducting) regions or increase the size of holes (or non-conducting areas) in large metal (or conducting) regions. This new mutation process uses an adjacency matrix that describes which conductive elements/pixels are touching each other. The adjacency matrix provides a two-dimensional metric describing which pixels are touching which other adjacent pixels. The adjacency matrix can range from 4 to 8 depending on the lattice type and the definition of touching. [0030] To demonstrate the efficacy of this adjacency-based mutation strategy, three consecutive design trials were conducted with the traditional mutation algorithm and with the new mutation algorithm. FIG. 9 illustrates the convergence of the fitness as a function of generation count. The fitness of any generation is the fitness of the best individual. The y-axis shows the average best individual across three trials. The adjacency-based mutation algorithm (curve 903 ) converges to a better score in less generations than the traditional mutation algorithm (curve 906 ). [0031] As shown in the table in FIG. 10 , the three trials with the adjacency-based mutation algorithm were each better than the corresponding trial with the traditional mutation algorithm. The values in the table in FIG. 10 also illustrate that when using an evolutionary algorithm (e.g., the genetic algorithm) to design a fragmented aperture antenna or any electromagnetic device, more than one design trial should be executed because as illustrated in this table, the subsequent designs can be more than a dB better than the first design. [0032] Examples of Fragmented Aperture Designs [0033] First Approach. The approach illustrated in FIG. 6 was used to design a series of fragmented aperture antennas that spanned from 500 MHz to 2.0 GHz. The lattice skew angle, X, was chosen to be tan −1 (2)˜63.435 degrees to give the desired left/right physical symmetry. The square pixels 103 were 10.8 mm on a side and the total aperture area was 25.4 cm×25.4 cm. Four representative aperture designs are shown in FIG. 11 . Each of the four sample antenna designs are excited at the terminal pair (feed point 1003 ) in the center with a 100 ohm transmission line. As the aperture designs in FIG. 11 show, none of the physical shapes of the designed antennas suffer from diagonal touching issues. [0034] The aperture designs (the placement of conducting and non-conducting regions) were performed using a genetic algorithm with adjacency-based mutation. For these designs, the 25.4 cm×25.4 cm area have 663 individual pixels. Enforcing left/right and top/down symmetry, there are 169 degrees of freedom. Hence assigning a single bit to represent the state of each area (1=conducting, 0=non-conducting) yields a 169 bit genetic code. Using a genetic population size of 32 antennas, 100 genetic algorithm generations was typically required to realize one of these sample designs. The genetic algorithm used a finite-difference time-domain (FDTD) numerical model of each antenna to compute return loss and radiation properties for the evolving population of antennas. The genetic algorithm fitness function rewarded good match (return loss better than 15 dB), and as large as possible, broadside realized gain. [0035] FIG. 12 shows the broadside realized gain of each antenna design, while FIG. 13 shows the return loss of each antenna. Curve 1203 shows the 0.5-0.8 GHz design, curve 1206 shows the 0.8-12 GHz design, curve 1209 shows the 1.2-1.6 GHz design, and curve 1212 shows the 1.6-2.0 GHz design. The gains are compared with an aperture gain limit (curve 1215 ). Since these apertures have no ground plane, the aperture gain limit for high frequencies is 2π(Area)/λ 2 . As shown in FIG. 13 , the VSWR of the four designs of FIG. 11 are below 1.5 across the respective design bands which is consistent with a return loss of better than 15 dB. Curve 1303 shows the 0.5-0.8 GHz design, curve 1306 shows the 0.8-12 GHz design, curve 1309 shows the 1.2-1.6 GHz design, and curve 1312 shows the 1.6-2.0 GHz design. [0036] Second Approach. The second approach illustrated in FIG. 7 is also useful for designing antennas. The second approach also supports left/right and top/down symmetry when appropriate. The aperture area was again 25.4 cm×25.4 cm and was excited in the center with a 100 ohm feed. The aperture has 841 shaped pixels. When left/right and top/down symmetry was enforced, the number of degrees of freedom dropped to 221. FIG. 14 shows examples of two designed apertures for the 0.5-0.8 GHz and the 0.8-1.2 GHz bands. The sample antenna designs are excited at the terminal pair (feed point 1003 ) in the center with a 100 ohm transmission line. [0037] FIG. 15 shows the broadside realized gain of the antenna designs, while FIG. 16 shows the return loss of the antennas. Curve 1503 shows the 0.5-0.8 GHz design and curve 1506 shows the 0.8-12 GHz design. The gains are compared with an aperture gain limit (curve 1515 ). In FIG. 16 , curve 1603 shows the 0.5-0.8 GHz design and curve 1606 shows the 0.8-12 GHz design. [0038] Third Approach. The third approach illustrated in FIG. 8 is also useful for designing antennas. However, for the design of vertically or Horizontal polarized elements with a broadside beam, the lack of left/right and top/down symmetry in the third approach is a drawback. For cases where the desired beam direction is not broadside or the desired polarization is different, then the pixelated aperture should not have symmetry and the third approach is comparable to the second or first approaches. [0039] It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations set forth for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims. [0040] It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed herein in a range format. It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a concentration range of “about 0.1% to about 5%” should be interpreted to include not only the explicitly recited concentration of about 0.1 wt % to about 5 wt %, but also include individual concentrations (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%) within the indicated range. The term “about” can include traditional rounding according to significant figures of numerical values. In addition, the phrase “about ‘x’ to ‘y’” includes “about ‘x’ to about ‘y’”.
Various examples are provided for fragmented aperture antennas. In one example, a fragmented aperture antenna includes a two-dimensional lattice of conducting elements, where positioning of the conducting elements in adjacent rows are offset based upon a fixed skew angle. In another example, a fragmented aperture antenna includes a two-dimensional lattice comprising a combination of first and second geometric conducting elements, where a second geometric conducting element provides a connection between adjacent sides of diagonally adjacent first geometric conducting elements. In another example, a fragmented aperture antenna includes a two-dimensional lattice of conducting elements having a single common non-rectangular shape, where the conducting elements interleave in a digitated fashion. Diagonally adjacent conducting elements overlap along a portion of adjacent edges of the diagonally adjacent conducting elements.
Identify and summarize the most critical technical features from the given patent document.
[ "CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to, and the benefit of, co-pending U.S. provisional application entitled “Fragmented Aperture Antennas”", "having Ser.", "No. 62/203,316, filed Aug. 10, 2015, which is hereby incorporated by reference in its entirety.", "BACKGROUND [0002] Originally, fragmented aperture antennas were envisioned as a planar surface with a grid of rectangular regions or pixels that are either conducting or non-conducting.", "A genetic algorithm (GA) and a computational electromagnetic model were used to determine which pixels should be conducting and which should be non-conducting to form an antenna surface suitable for a given use.", "BRIEF DESCRIPTION OF THE DRAWINGS [0003] Many aspects of the present disclosure can be better understood with reference to the following drawings.", "The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure.", "Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.", "[0004] FIGS. 1 through 4 illustrate examples fragmented aperture antennas in accordance with various embodiments of the present disclosure.", "[0005] FIGS. 5A through 5D illustrate examples of fragmented aperture antenna designs addressing diagonal touching in accordance with various embodiments of the present disclosure.", "[0006] FIGS. 6 through 8 illustrate examples fragmented aperture antenna designs that avoid diagonal touching in accordance with various embodiments of the present disclosure.", "[0007] FIG. 9 illustrates an example of fitness score for a traditional mutation algorithm and an adjacency-based mutation algorithm as a function of generation count in accordance with various embodiments of the present disclosure.", "[0008] FIG. 10 is a table illustrating a comparison of the traditional mutation algorithm and the adjacency-based mutation algorithm in accordance with various embodiments of the present disclosure.", "[0009] FIG. 11 illustrates examples of representative aperture designs based upon the arrangements of FIG. 6 in accordance with various embodiments of the present disclosure.", "[0010] FIGS. 12 and 13 illustrate test results of the representative aperture designs of FIG. 11 in accordance with various embodiments of the present disclosure.", "[0011] FIG. 14 illustrates examples of representative aperture designs based upon the arrangements of FIG. 7 in accordance with various embodiments of the present disclosure.", "[0012] FIGS. 15 and 16 illustrate test results of the representative aperture designs of FIG. 14 in accordance with various embodiments of the present disclosure.", "DETAILED DESCRIPTION [0013] Disclosed herein are various embodiments related to fragmented aperture antennas.", "Reference will now be made in detail to the description of the embodiments as illustrated in the drawings, wherein like reference numbers indicate like parts throughout the several views.", "[0014] The physical shape and size of highly pixelated apertures can been optimized using genetic algorithms (GA) and full-wave computational electromagnetic simulation tools (i.e. FDTD) to best meet desired antenna performance specifications (e.g., gain, bandwidth, polarization, pattern, etc.).", "FIG. 1 shows an example of a fragmented aperture antenna including a grid of rectangular pixels 103 a. Visual inspection of the design shows that the metallic pixels 103 form many connected and disconnected fragments.", "Hence, the term fragmented aperture antenna has been coined for this class of antennas.", "The approach illustrated in FIG. 1 has been successfully used to design novel antennas.", "This concept can be generalized to conducting or non-conducting parallelogram pixels 103 b as shown in FIG. 2 .", "[0015] However, the original fragmented design approach suffers from two major deficiencies.", "First, the placement of pixels 103 on a generalized, rectilinear grid leads to the problem of diagonal touching as illustrated in the top right of FIGS. 1 and 2 .", "Pixels 103 that touch diagonally (i.e., diagonal touching 106 ) lead to poor measurement/model agreement.", "Second, the convergence in the GA stage of the design process is poor for high pixel count (>>100) apertures.", "[0016] Diagonal touching 106 is not a problem during the design phase because in the numerical models the diagonally touching 106 of pixels 103 in the antenna are always touching.", "However, when fabricated using approaches such as printed circuit board etching, the pixels 103 are often disconnected because of over-etching.", "FIG. 3 illustrates an example of over-etching 109 that can lead to diagonal touches 106 between conducting regions 103 being disconnected.", "Disconnecting metal pixels 103 that should be connected within an antenna causes problems with the antenna impedance and gain characteristics.", "[0017] In fact, nearly every fragmented aperture antenna design presented in U.S. Pat. No. 6,323,809 suffers from this issue of diagonal touching.", "FIG. 4 illustrates examples of diagonal touching 106 in two designs from U.S. Pat. No. 6,323,809.", "It has been noted that if the pixels 103 have edges parallel to the lattice forming vectors (as in the approaches of FIGS. 1 and 2 ), then the issue of “diagonal touching”", "106 will persist.", "Various approaches will be presented that have been successfully used to mitigate these diagonal touching issues.", "[0018] Mitigation of Diagonal Touching [0019] One approach utilizes a super-cell approach as illustrated in FIG. 5A .", "A super-cell 503 is a collection of smaller areas such as, e.g., a 3 by 3 lattice of the smaller pixels or sub elements 506 as shown in FIGS. 5A-5D .", "To avoid diagonal touching 106 , define the conducting region or pixel 509 as covering the 5 sub-elements 506 that defined a plus sign within the super-cell 503 .", "Hence, the absence of conducting material in the corners of the super-cell 503 prevents any potential for diagonal touching 106 .", "This successfully allows antennas to be designed and fabricated with a high probability of good correlation between measured and modeled characteristics of the antenna.", "In this approach, the electrical currents are constrained to flow in only grid conforming directions, which may limit optimization of the antenna designs.", "[0020] Another approach includes fabrication of every pixel 103 with an area that is roughly 10% larger than designed, as illustrated in FIG. 5B .", "Oversizing the pixels 103 ensures diagonal touching 106 by overlapping with diagonally adjacent pixels 103 .", "This approach was found to lead to a high percentage of good fabricated antennas.", "However, this approach leads to the antennas having approximately 10-20% more conductor area than originally designed, which can lead to less than desired antenna characteristics in the fabricated antennas.", "[0021] It is worth noting that fabricating the conducting pixels 103 to be 10% smaller, would guarantee the pixels 103 would never diagonally touch 106 , but this would lead to antennas that never have conducting areas larger than one pixel 103 , which would almost never be any good.", "Also, this would be contrary to the numerical models used in design where the conducting elements 103 always touch when diagonally adjacent.", "[0022] Other implementations include a variant of the slightly larger pixel strategy of FIG. 5B , where a small patch 512 of conducting material or metal is placed at the diagonal touching location as shown in FIG. 5C .", "The small patch 512 can be a square as illustrated in FIG. 5C or other appropriate geometrical shape.", "Another implementation is illustrated in FIG. 5D , where one of the two open pixel locations adjacent to the diagonal touching 106 is coated with conductive material.", "A random coin flipping process can be used to decide which of the two non-conducting pixel locations to make conducting to fix the diagonal touch 106 as shown in FIG. 5D .", "[0023] Various approaches for avoiding diagonal touching 106 by breaking the dependence of element edges and lattice directions implicit in FIGS. 1 and 2 will now be discussed.", "Three approaches for breaking this dependence are presented which can lead to improved fragmented aperture antennas.", "[0024] First Approach.", "In a first approach to improve the fragmented apertures, the location of individual conducting/non-conducting elements can be defined using a second set of directions (or lattice vectors) that are not both parallel with the lattice constants or edges of the conducting regions or pixels 103 as illustrated in FIG. 6 .", "In the example of FIG. 6 , the antenna comprises a lattice of square or rectangular conducting elements 103 where the lattice includes an X degree skewed lattice such that the adjacent conducting regions 103 are offset from each other based on the skew.", "Edge vectors E 1 and E 2 define the lattice constants with at least one of the lattice vectors V 1 and/or V 2 not being in parallel with E 1 or E 2 .", "In FIG. 6 , skewing the lattice vector V 2 has removed the diagonal touching possibility.", "The skew angle X will be less than 90 degrees, and can be in a range from 75 degrees to 45 degrees, a range from 60 degrees to 45 degrees, or in a range from 70 degrees to 50 degrees.", "In the examples of FIG. 11 , the skew angle is about 63 degrees.", "In some implementations, both lattice vectors V 1 and V 2 may be skewed.", "[0025] Second Approach.", "In a second approach to improve the fragmented apertures, the shapes of fundamental conducting regions and non-conducting regions can alternate such that the conducting elements 703 diagonally touch in a definite manner as illustrated in FIG. 7 .", "In the example of FIG. 7 , the shapes of the two regions comprise an octagon and a diamond.", "Other combinations of geometric shapes can be chosen such that the pair of shapes tessellate the plane.", "[0026] Third Approach.", "In a third approach to improve the fragmented apertures, the shape of the fundamental conducting regions and non-conducting regions is chosen such that the single shape tessellates the plane and does not touch diagonally.", "FIG. 8 shows one example of such a conducting element or pixel 803 , but many other shapes can also be utilized.", "The shape of the conducting element 803 in FIG. 8 is a skewed-Z that allows the regions to be interleaved in an interdigitated fashion to cover the plane.", "[0027] Mutation Algorithm to Improve Convergence Rate of Fragmented Apertures [0028] Traditionally, fragmented aperture antennas are designed using evolutionary algorithms like the genetic algorithm of U.S. Pat. No. 6,323,809, which is hereby incorporated by reference in its entirety.", "One important step in the genetic algorithm is called mutation.", "In a standard genetic algorithm, mutation is a random process where a small number of genes are changed each generation to help avoid convergence to a suboptimal solution.", "For a fragmented antenna, mutation makes a few pixels randomly conducting or not in the next population of antennas.", "Many of these mutations will create only an isolated metal pixel or small hole in metal that will have a very negligible effect on the antenna performance.", "[0029] A modified mutation algorithm tailored for fragmented aperture antennas can be introduced to help speed up the convergence of the design process when the number of elements/pixels is high.", "The goal of the new or modified mutation process is to bias mutation to either increase the size of conducting fragments in empty (or non-conducting) regions or increase the size of holes (or non-conducting areas) in large metal (or conducting) regions.", "This new mutation process uses an adjacency matrix that describes which conductive elements/pixels are touching each other.", "The adjacency matrix provides a two-dimensional metric describing which pixels are touching which other adjacent pixels.", "The adjacency matrix can range from 4 to 8 depending on the lattice type and the definition of touching.", "[0030] To demonstrate the efficacy of this adjacency-based mutation strategy, three consecutive design trials were conducted with the traditional mutation algorithm and with the new mutation algorithm.", "FIG. 9 illustrates the convergence of the fitness as a function of generation count.", "The fitness of any generation is the fitness of the best individual.", "The y-axis shows the average best individual across three trials.", "The adjacency-based mutation algorithm (curve 903 ) converges to a better score in less generations than the traditional mutation algorithm (curve 906 ).", "[0031] As shown in the table in FIG. 10 , the three trials with the adjacency-based mutation algorithm were each better than the corresponding trial with the traditional mutation algorithm.", "The values in the table in FIG. 10 also illustrate that when using an evolutionary algorithm (e.g., the genetic algorithm) to design a fragmented aperture antenna or any electromagnetic device, more than one design trial should be executed because as illustrated in this table, the subsequent designs can be more than a dB better than the first design.", "[0032] Examples of Fragmented Aperture Designs [0033] First Approach.", "The approach illustrated in FIG. 6 was used to design a series of fragmented aperture antennas that spanned from 500 MHz to 2.0 GHz.", "The lattice skew angle, X, was chosen to be tan −1 (2)˜63.435 degrees to give the desired left/right physical symmetry.", "The square pixels 103 were 10.8 mm on a side and the total aperture area was 25.4 cm×25.4 cm.", "Four representative aperture designs are shown in FIG. 11 .", "Each of the four sample antenna designs are excited at the terminal pair (feed point 1003 ) in the center with a 100 ohm transmission line.", "As the aperture designs in FIG. 11 show, none of the physical shapes of the designed antennas suffer from diagonal touching issues.", "[0034] The aperture designs (the placement of conducting and non-conducting regions) were performed using a genetic algorithm with adjacency-based mutation.", "For these designs, the 25.4 cm×25.4 cm area have 663 individual pixels.", "Enforcing left/right and top/down symmetry, there are 169 degrees of freedom.", "Hence assigning a single bit to represent the state of each area (1=conducting, 0=non-conducting) yields a 169 bit genetic code.", "Using a genetic population size of 32 antennas, 100 genetic algorithm generations was typically required to realize one of these sample designs.", "The genetic algorithm used a finite-difference time-domain (FDTD) numerical model of each antenna to compute return loss and radiation properties for the evolving population of antennas.", "The genetic algorithm fitness function rewarded good match (return loss better than 15 dB), and as large as possible, broadside realized gain.", "[0035] FIG. 12 shows the broadside realized gain of each antenna design, while FIG. 13 shows the return loss of each antenna.", "Curve 1203 shows the 0.5-0.8 GHz design, curve 1206 shows the 0.8-12 GHz design, curve 1209 shows the 1.2-1.6 GHz design, and curve 1212 shows the 1.6-2.0 GHz design.", "The gains are compared with an aperture gain limit (curve 1215 ).", "Since these apertures have no ground plane, the aperture gain limit for high frequencies is 2π(Area)/λ 2 .", "As shown in FIG. 13 , the VSWR of the four designs of FIG. 11 are below 1.5 across the respective design bands which is consistent with a return loss of better than 15 dB.", "Curve 1303 shows the 0.5-0.8 GHz design, curve 1306 shows the 0.8-12 GHz design, curve 1309 shows the 1.2-1.6 GHz design, and curve 1312 shows the 1.6-2.0 GHz design.", "[0036] Second Approach.", "The second approach illustrated in FIG. 7 is also useful for designing antennas.", "The second approach also supports left/right and top/down symmetry when appropriate.", "The aperture area was again 25.4 cm×25.4 cm and was excited in the center with a 100 ohm feed.", "The aperture has 841 shaped pixels.", "When left/right and top/down symmetry was enforced, the number of degrees of freedom dropped to 221.", "FIG. 14 shows examples of two designed apertures for the 0.5-0.8 GHz and the 0.8-1.2 GHz bands.", "The sample antenna designs are excited at the terminal pair (feed point 1003 ) in the center with a 100 ohm transmission line.", "[0037] FIG. 15 shows the broadside realized gain of the antenna designs, while FIG. 16 shows the return loss of the antennas.", "Curve 1503 shows the 0.5-0.8 GHz design and curve 1506 shows the 0.8-12 GHz design.", "The gains are compared with an aperture gain limit (curve 1515 ).", "In FIG. 16 , curve 1603 shows the 0.5-0.8 GHz design and curve 1606 shows the 0.8-12 GHz design.", "[0038] Third Approach.", "The third approach illustrated in FIG. 8 is also useful for designing antennas.", "However, for the design of vertically or Horizontal polarized elements with a broadside beam, the lack of left/right and top/down symmetry in the third approach is a drawback.", "For cases where the desired beam direction is not broadside or the desired polarization is different, then the pixelated aperture should not have symmetry and the third approach is comparable to the second or first approaches.", "[0039] It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations set forth for a clear understanding of the principles of the disclosure.", "Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the disclosure.", "All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.", "[0040] It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed herein in a range format.", "It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.", "To illustrate, a concentration range of “about 0.1% to about 5%”", "should be interpreted to include not only the explicitly recited concentration of about 0.1 wt % to about 5 wt %, but also include individual concentrations (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%) within the indicated range.", "The term “about”", "can include traditional rounding according to significant figures of numerical values.", "In addition, the phrase “about ‘x’ to ‘y’”", "includes “about ‘x’ to about ‘y’.”" ]
BACKGROUND OF THE INVENTION [0001] This request is, in parts, a continuation of the U.S. Pat. No. 8,815,393 B2, “Process for obtaining functionalized nanoparticulate magnetic ferrites for easy dispersion and magnetic ferrites obtained through the same” which derives from the Brazilian patent application, PI 1002273-2, “Processo de obtenção de ferritas magnéticas nanoparticuladas e funcionalizadas para fácil dispersão e ferritas magnéticas obtidas através do mesmo”. That patent, from the same company (Nanum Nanotechnology SA) and from the same inventors, describes a novel process to produce nanoparticle magnetic ferrites and its dispersions, also known as ferrofluids, for various applications mentioned therein, including the production of magnetic inkjet inks. The present invention presents in detail the process to transform the innovative water based magnetic dispersion described in that patent into innovative water based magnetic inkjet ink for MICR (Magnetic Ink Character Recognition) applications. [0002] Technologies for inkjet printing and the production of inkjet inks have been around for several decades. They contain, in general, dyes and/or pigments, surfactants, humectants, biocides, among others. The inkjet ink formulation also requires very specific situations in terms of viscosity, surface tension, drying rates, etc. Similarly, magnetic MICR printing technologies have decades of evolution involving the particles and the physical and magnetic characteristics thereof. [0003] The technology to produce water based magnetic inkjet ink for MICR applications usually can be divided into two consecutives and interdependent processes. The first one is the manufacture or suspension (by dispersing, milling, etc) or adjustment of the magnetic particles in a stable aqueous dispersion (ferrofluid) with a high solids concentration, always higher than the final ink. The second one is the ink formulation directed to the specificities of inkjet printing technologies. The two main digital print technologies are thermal and piezoelectric, which may happen by continuous flow (bulk) or by cartridges with defined volumes. These printing characteristics define the physicochemical properties that the ink should have during the printing process such as dynamic viscosity, surface tension and evaporation during the drop formation, and the drying speed and the characteristic of the ink penetration into the substrate after drop formation. The ink formulation results in the setting of these parameters and is closely linked to the characteristics of the initial dispersion and its stability. [0004] One of the main challenges of magnetic ink jet printing technology is that the cartridge nozzles are extremely small, on the order of 1 μm in diameter maximum, requiring then magnetic pigments of sub micron order to avoid clogging. Since the magnetic signal response is proportional to the particle size and its mass, the other challenge is to achieve a stable dispersion for high concentrations of pigments, in such a way that in a single printing process the magnetic signal reaches the intensity required for MICR readers available on the market. Typically, concentrations between 15% and 35% are used in standard MICR ink on the market. Such pigment concentration becomes detrimental to the orifices of the print head of ink jet system due to their rheological characteristics, such as high viscosity and high drying rate making the shear stress a factor of great importance. Furthermore, these pigments may consist of considerable hardness materials where the print head damage due to their abrasiveness should be considered. SUMMARY OF INVENTION [0005] The present invention starts from an innovative process to obtain a water-based dispersion with high stability, based on strong chemical bonds as opposed to other technologies that use chemical interactions only, such as Van der Waals forces, to maintain the stability of the dispersion, which means, long range forces much weaker than chemical bonds. These interactions are obtained using coatings, surfactants, etc. as opposed to use an initial surface treatment of the magnetic particles with subsequent chemical binding of a selected compound (functionalizer) which will be responsible to also interact with water. We call this process as functionalization. [0006] The magnetic particles production and its water based ferrofluid (or aqueous dispersion) is already discussed in great detail at the U.S. Pat. No. 8,815,393 B2 as well as its process and its differentiation in relation to other existing patents. We add on this request some other quotes that drive the title of the invention and the specific claims for aqueous MICR printing inks in inkjet printers. [0007] The patents of Xerox Corporation U.S. Pat. No. 8,409,341 B2 and U.S. Pat. No. 8,597,420 B2 include MICR inks for inkjet printing, but are specific to solvent-based ink formulations. On the other hand, the U.S. Pat. No. 8,236,192 B2 includes water based formulations too. They are inks based on single crystals of stabilized magnetic nanoparticles, single crystals containing domains at least 10 nm, and the absolute value of magnetic anisotropy greater than or equal to 2×10 4 J/m 3 . These simple magnetic crystals are composed of at least one metal nanoparticle involving Fe, Co or Mn. Such nanoparticles may also be bimetallic or trimetallic selected from the following group of choices FePt, CoPt, MnAl, MnBi, CoO.Fe 2 O 3 and BaO.6Fe 2 O 3 , plus Fe and Co. Intervals of remanence, coercivity and magnetic moment of saturation are set for them. Several ink compositions are disclosed, primarily for nonpolar carriers where dyes, resins and surfactants are added. For aqueous dispersions, anionic surfactants and other ingredients are added while the particles are milled with ball mill for several hours. [0008] The present invention differs from Xerox technology in various aspects. First, it is a water borne dispersion, which precludes any similarity to the first two Xerox quotes that are based on non-polar solvents. In the third Xerox patent, U.S. Pat. No. 8,236,192 B2; all of the magnetic pigment dispersions undergo a process of comminution, by milling or using high shear rate mixers. Furthermore, the stabilization of the particles does not occur with a functionalization of them, as well as discussed in the example below. [0009] The Nu-Kote International, Inc. patents, number U.S. Pat. No. 6,746,527 B1; U.S. Pat. No. 6,767,396 B2 and U.S. Pat. No. 6,726,759 B2 deal with the compositions of aqueous inks for inkjet MICR printing using metal oxides. The particles or the metal oxide pigments should have a size less than 0.5 microns and remanence of at least 20 emu/g. One such patent (U.S. Pat. No. 6,767,396 B2) teaches us about the preparation of the possible metal oxide pre-dispersions as a basis for the formulations of the claimed MICR inks. In all cases the pre-dispersions start with the mixture of water with at least one surfactant and will slowly by adding the magnetic powder pigment, or the metal oxide particles selected from specified groups. This magnetic pigment can also be made of metal oxide particles coated with hydrophilic inorganic silicates such as aluminum silicate, sodium silicate and potassium silicate. Once ready these pre-dispersions a sequence of grinding processes and filtration begin, conventional and/or unconventional, in order to mix the ink and further reduce the particle size. The other two Nu-Kote patents (U.S. Pat. No. 6,726,759 B2 and U.S. Pat. No. 6,746,527) seek to be wider in the previous patent requested claims increasing the list of surfactant possible to use. The same applies to the materials for the hydrophilic coating dispersion in the wet cake form, the metal oxide used and its remanence intervals. Also extend to the composition of the final ink produced from these pre-dispersions working with dyes and aqueous solvents. [0010] About the pre-dispersion, Nu-Kote technology uses a process typically classified as “top-down”, in which sub-micrometer metallic oxide particles are crushed and filtered while interacting with aqueous base containing a surfactant or a combination of them. At this stage the particles have already some differences, especially regarding the shape of the particles size distribution curve, besides that on the present invention the magnetic metal oxides particles are chemically synthesized by precipitation, classifying the case as “bottom-up”. However, it is in the dispersion technology and in the stabilization of these dispersions that the distance to the present invention provokes most of the differences. Inks originating from each of the technologies will exhibit quite different rheological characteristics and formulations. [0011] The pre-dispersions are very distinct from the present invention. All teaching and claims of Nu-kote revolves around the basic need to use a surfactant or a combination thereof throughout the process to ensure the stability of the aqueous dispersion, while dispersion in the present invention is independent of the surfactant in such a way that even if it is added subsequently to ink formulation in small quantity it will act only as a corrective surface tension, not to stabilize the dispersion of magnetic pigment. The Nanum keeps in its laboratory one of its first aqueous magnetic dispersions produced in September 2009 where no surfactant was added. After several years dispersion remains stable, although part of the water has evaporated and the solid concentration which was originally 50% being currently around 65%. This distinction can also be observed easily by noting that even with solids concentrations as high as 65% dispersion of the present invention further presents its fluid character, while the patent Nu-kote to work with concentrations around 58% was classified as paste (wet cake form). [0012] Although the coating process is quite different from the functionalization process of the magnetic particles used at the present invention, Nu-kote technology may alternatively use hydrophilic compounds to obtain coated particles. The compounds listed for the coatings are aluminum silicates, inorganic silicates, metal stearates, ester metal phosphates, metal sulfonates, and the like, where no such compounds are used in the functionalization process of the present invention. [0013] It is also possible to perform an estabilization of two layers made according to the teachings of Shimoiizaka et al. (U.S. Pat. No. 4,094,804) in which the oleic acid is used as the first functionalizing layer, by chemical bond, creating the connections between the particles and unsaturated fatty acids in the second layer, by long range interactions. Thus, the aqueous dispersion of Shimoiizaka always happen in the presence of this second component, which now acts as a recoating which will be limited by physical adsorption of the second layer, thereby compromising the stability of the dispersion with a weaker bond, as described by himself (col 3-ln 45). [0014] The technology route taught here uses a single layer of functionalizing strongly attached to the particle via chemical bonds. Thus, with more flexibility, for polar bases we can choose between amino acids, tartaric acid, citric acid or oxalic acid. This step is preceded by attack on the surface by using mineral acids (instead of organic acids such as oleic acid) or strong bases, depending on the particle composition. As these processes will release various ions in the solution, a washing process becomes very important in this technology to remove ions and other salts, which can block the particle surface or contribute to the instability of the same system due to the increased conductivity. In the Shimoiizaka process the particles can not and is not washed at this point, because such process could lead to losses of part of the surfactant loosely bound to the outer layer. [0015] Having this unique dispersion, super stable in aqueous basis, the present invention solves MICR printing ink formulation relatively simple and uncomplicated, requiring only the adjustments of viscosity, surface tension, drying time, and biocides, depending on the printing technology and substrates to be considered. One of the most important and necessary characteristics in the ink formulation of the present invention is the use of special humectant compounds to ensure the moist property of the printing head surface having an ink with high solids concentration, but also to avoid the accumulation of material after the jetting, avoiding the impregnation of organic and inorganic part and leaving the printing head clean and unblocked. From the large amount of existing humectant compounds the polyols which exhibit excellent performance for this technology are bis-(cyanoethyl)-dihydroxypropylamine (known as “C-1”), bis-(2-hydroxyethyl) glycolamide (known as “BHEGA”), bis-(hydroxyethyl)-lactamide (known as “BHELA”) and bis-(hydroxyethyl) dimethyl hydantoin (referred to as “DANTOCOL EHD”). [0016] The most interesting of the present invention is that the nanostructure formed by the nano composite magnetic pigment, their water based functionalizer and humectant compounds create a unique system that reduces the dispersion shear stress with greater fluidity and low abrasiveness, preserving the printhead of the inkjet printer. AIM OF THE INVENTION [0017] The main aim of this invention is to provide a method of obtaining magnetic water based inks to jetprint MICR (Magnetic Ink Character Recognition) starting from dispersions of functionalized magnetic ferrites nanoparticles, obtained according to U.S. Pat. No. 8,815,393 B2. Some of these dispersions are already available in the global market being offered by the Nanum Nanotecnologia SA, such as Nanumadit AT-0701, AT-0716, AT-2701, AT-2801, etc. [0018] Another aim of the present invention is the production of aqueous MICR inks with extremely high concentrations of magnetic nanoparticles with loading between 15% and 40% by mass, keeping them stable for several months and creating a system that protects the printhead of inkjet cartridges against the effect of high ceramics load, having less abrasiveness and greater fluidity. DESCRIPTION OF THE DRAWINGS [0019] FIG. 1 : hydrodynamic size distribution of particles, by the technique of Dynamic Light Scattering (DLS) of Nanumadit NA-0701 additive. DETAILED DESCRIPTION OF THE INVENTION [0020] To obtain aqueous MICR inks for inkjet printing starts from aqueous dispersion of functionalized nano-sized magnetic ferrite produced according to the process described in U.S. Pat. No. 8,815,393 B2. Nanometrics, simple or compound magnetic ferrites are chemically synthesized by co-precipitation where their physical and magnetic characteristics can be adjusted as needed. These adjustments are possible by modifying the composition of the metal oxide according to the following criteria for simple ferrite (MFe2O4 or MFe12O19) or for compound ferrites (N×M(1-x)Fe2O4 or N(1-y)Mx+YFe(2-x)O4, for example) where M and N can be metal atoms such as Sm, La, Bi, Ba, Mo, Sr, Ni, Co, Fe, Mn, Cr, etc. These ferrites exhibit a particle size distribution ranging from 15 to 300 nm, preferably between 15 and 120 nm, as shown in FIG. 1 below, with a surface area between 10 and 120 m2/g, preferably between 25 and 90 m2/g. Presenting also magnetic saturation between 05 and 80 emu/g, magnetic remanence ranging from 1 to 60 emu/g magnetic coercivity of from 10 to 3000 Oe, a magnetic saturation, preferably between 30 to 80 emu/g, magnetic remanence from 10 to 30 emu/g, and magnetic coercivity between 200 and 800 Oe. [0021] The following Table 1 shows some practical results: [0000] TABLE 1 Magnetic properties of the additives used in the MICR ink production. Hc Mr Ms Nanumadit (Oe) (emu/g) (emu/g) Composition NA-2601 34 3 55 Manganese, Boron ferrite NA-2701 724 4 15 Barium, Cobalt ferrite NA-2801 553 15 41 Cobalt. Cerium ferrite NA-0701 347 19 62 Manganese, Cobalt ferrite NA-2901 238 14 54 Manganese, Gadolinium, Cobalt ferrite NA-3001 1201 25 42 Barium ferrite Hc: coercive field, Mr: remnant magnetization, Ms: saturation magnetization [0022] After this co-precipitation process, a surface treatment of the particles occurs with the addition of a strong acid or base solution, followed by a first wash, thereby preparing the material for functionalization. The functionalization for aqueous base can be accomplished with a functionalizer, or a combination thereof, chosen from oxalic acid, citric acid, tartaric acid and amino acids. The material obtained by the functionalization with adjusted pH is then washed again. This second wash may occur by filtration, dialysis and/or decantation mixing water and organic solvents. So far all follow the procedures set forth in U.S. Pat. No. 8,815,393 B2 and the resultant ferrofluid with solids concentration between 35% and 55%, preferably 50%, is directed to the manufacture of ink without the necessity of transformation into a powder. Some weak agglomeration may occur at this time, particularly if the ferrofluid is stored for a long period, and in this case, a physical deagglomeration action can occur, such as a gentle grinding to not damage the particle/functionalizing system. Preferably the deagglomeration is done by ultrasound. In general, the ferrofluid, the standard dispersion to produce MICR ink for ink jet printing has the following characteristics: viscosity between 40 and 400 cP for a suspension of 50% m/m and a pH between 5 and 8. In Table 2, below shows practical results of these Nanum dispersions that are already in the market. [0000] TABLE 2 Physical and chemical properties of magnetic additives used in MICR ink production. Viscosity Nanumadit (cP) pH NA-0701 150-200 6.5-7.0 NA-0716 350-400 7.0-8.0 NA-2701 300-380 6.5-7.0 NA-2801 250-350 6.5-7.0 [0023] In general, the requirements for an adequate MICR ink is to have good print quality, stability, do not cause printhead clogging, good magnetic reading, low kogation, and longprinting decap time. The quality of ink printing includes good definition of the printed characters, driven mainly by the physicochemical characteristics of it, such as viscosity and surface tension. The stability of the ink is closely linked to the stability of the dispersion and the dispersion with the mixing of other solvents, thus other solvents which comprises the ink cannot destabilize the initial dispersion. The ink destabilization leads to clogging of the of the printhead nozzles. Another cause of clogging of these orifices is any failure in the process that allows, for example, contamination by dust or other materials. Typically, all the ink undergoes a final filtration process with filter elements of 0.2 microns to guarantee this does not cause clogging. [0024] In addition, another major cause of clogging and printing failure is the drying of ink or the deposition of decomposed ink through the nozzles (kogation). It is necessary to balance the ink drying time in such a way that as soon as the ink jet exits the nozzles, ink blots and scattering does not occur in the already printed substrate and this variable also depends on the printer technology and printing speed. Thus, it is common to use specific and adapted inks to the various printheads and inkjet technologies (thermal, piezoelectric, etc.). This need for fast ink drying on the substrate also leads to the drying of the ink at the edge of the print nozzles when printing stops. In the return of the activities the dry film should be quickly and completely eliminated to avoid compromising the next print quality, so get a good printing decap time is also key. To analyze and monitor the behavior of the ink decap time and kogation 25 cm solid-fill printing evaluations are performed on the time of the cartridge filling and then after resting for 5 minutes, 30 minutes, 1 day, 7 days and 30 days with no external device that stimulates jetting. In none of these cases the print quality may be compromised. [0025] With the dispersions based on functionalized nanoparticles, key feature of this technology presented here, the stability of the ink is not a problem and all eyes are basically focused on print quality, drying time, kogation and decap time. [0026] The production of the MICR ink starts by the manipulation of other solvents (such as -pyrrolidone, n-methyl-pyrrolidone, buthyldiglycol, etc) that comprise the aqueous base and will receive the generated or previously acquired magnetic dispersion. The solvents on this technology contain polyols and other humectants which influence the drying time, penetration of the ink into paper or other substrate, and decap time. From the large amount of existing polyols and other humectants compounds which exhibit excellent performance for this technology the preferred are glycerin, diethylene glycol, polyethylene glycol, etilenoglicolmonoetileter, sorbitol, mannitol, glicereth bis-(cyanoethyl)-dihydroxypropylamine (known as “C-1”), bis-(2-hydroxyethyl) glycolamide (known as “BHEGA”), bis-(hydroxyethyl)-lactamide (known as “BHELA”) and bis-(hydroxyethyl) dimethyl hydantoin (referred to as “DANTOCOL EHD”). [0027] Immediately after homogenizing the aqueous ink base it is added a sufficient amount of the magnetic dispersion (Nanumadit) and new mixing is processed. Depending on the print head and jet firing technology, wetting agents are added to adjust the surface tension, as well as biocides. The ink is then filtered and is ready for storage, supply cartridges, shipment, etc. [0028] In general, the MICR inks are characterized by viscosity up to 18 cPs, a density between 1.2 and 1.7 g/cm 3 , surface tension between 25 and 55 dyne, conductivity between 500 and 1000 μS·cm-1, neutral pH (˜7), particle size smaller than 200 nm and magnetization between 80% and 200% as measured, for example, using the MICR Qualifier equipment from the RDM Corporation. [0029] Following are examples of the process and products claimed: Example I [0030] The formula is manipulated by homogenization of components forming the basis of the ink which is aqueous. To ensure humectation, decap time and printing head protection diethylene glycol (2%), glycerin (1%) and Dantocol DHE (3%) are added plus 2-pyrrolidone (5%) and butyldiglycol (1%) for drying. Besides influencing the drying time, 2-pyrrolidone improves print quality and butyldiglycol allows greater penetration of the ink into the paper. Water completes the base formulation with 28%. The rest 60% is the ferrofluid Nanumadit NA-0701, synthesized such as described in U.S. Pat. No. 8,815,393 B2 and added in a second step. In this formulation ferrofluid contains 50% of solids and is comprised of a cobalt and manganese ferrite functionalized with citric acid using water as the carrier. The ink base plus the ferrofluid is now homogenised for 60 minutes at 230 rpm without heating. biocide was added to control the growth of microorganisms. This ink has for example printed using HP122 cartridge reaching average magnetization of 110% using IDAutomationSCMC7 source; size 12; and paper weights of 120 g/m 2 . Example II [0031] In this other formulation, also aqueous, it is added glycerin (7%), BHELA (5%) and polyethylene glycol 6000 (2.5%). Water completes the base formulation with 21.5%. After homogenization the base is added to the magnetic loading (64%)—Nanumadit 0701. Mixing is carried out for 60 minutes more at 230 rpm without heating. The ink is then filtered through 0.5 μm absolute filter. Wetting agents and biocide were added to adjust the surface tension of the cartridge in the acceptable range and control the growth of microorganisms. This formulation has been developed for high-speed printers with piezo printhead, such as Kyocera KJB4 printhead. Example III [0032] Another formulation was developed using now Nanumadit NA-0716 additive. It was mixed for humectation diethylene glycol (2%), glycerin (2%) and C-1 (5%) and 2-pyrrolidone (10%) for drying, and print quality. Water is added (26%) to complete the base formulation. In a second step it was added the magnetic loading (55%)—0716 Nanumadit synthesized according to U.S. Pat. No. 8,815,393 B2. In this formulation the ferrofluid contains 50% solids and is comprised of a cobalt and manganese ferrite functionalized with histidine using water as the carrier medium. Homogenization is carried out for 60 minutes at 230 rpm without heating. Wetting agents and biocide were added to adjust surface tension and control the growth of microorganisms. This ink was printed using HP45 cartridge reaching average magnetization of 150% using IDAutomationSCMC7 source; size 12; and paper weights 90 g/m2. Example IV [0033] This aqueous base formulation was prepared with the additive Nanumadit NA-2701. For the base of the ink were mixed glycerol (7%), Dantocol DHE (5%), 2-pyrrolidinone (7%), Cab-o-jet 300 (10%) and water (11%). In a second step it was added the magnetic loading (60%)—2701 Nanumadit synthesized as described in U.S. Pat. No. 8,815,393 B2. In this formulation ferrofluid contains 50% solids and is comprised of a cobalt ferrite and barium functionalized with citric acid using water as the carrier medium. The homogenization was performed during 60 minutes at 230 rpm without heating. The ink was filtered through 0.2 μm absolute filter. Wetting agents and biocide were added to adjust surface tension and control the growth of microorganisms. This formulation was developed for high-speed printers with piezo print head, such as the Ricoh Gen4 head. Example V [0034] Another aqueous formulation was prepared using the additive Nanumadit NA-2801. Diethylene glycol (1%), glycerin (1%), polyethylene glycol 600 (1.5%), Dantocol DHE (3%), 2-pyrrolidone (5%), butyl diglycol (0.5%) and water (38%) were mixed to form the base of the ink. In a second step was added the magnetic loading (50%)—Nanumadit 2801, synthesized as disclosed in U.S. Pat. No. 8,815,393 B2. In this formulation ferrofluid contains 50% solids and is comprised of a cobalt and cerium ferrite functionalized with citric acid using water as the carrier medium. Homogenization is carried out for 60 minutes at 230 rpm without heating. Wetting agents and biocide were added to adjust surface tension and control the growth of microorganisms. This ink was printed using HP45 cartridge reaching average magnetization of 100% using IDAutomationSCMC7 source; size 12; and paper weights 140 g/m 2 . Example VI [0035] For the base of this ink formulation were mixed diethylene glycol (1%), glycerin (2%), BHELA (4%), n-methylpyrrolidone (8%) and water (25%). In a second step the magnetic loading was added (60%)—2812 Nanumadit synthesized as described in U.S. Pat. No. 8,815,393 B2. In this formulation ferrofluid contains 50% solids and is comprised of a cobalt and cerium ferrite functionalized with tartaric acid using water as the carrier medium. The homogenization was performed during 60 minutes at 230 rpm without heating. The ink was first filtered through a 1.0 μm nominal filter and an absolute filter followed by 0.5 μm. Wetting agents and biocide were added to adjust surface tension and control the growth of microorganisms. This ink was printed using HP45 cartridge reaching average magnetization of 120% using IDAutomationSCMC7 source; size 12; and paper weights 90 g/m 2 .
The present invention describes a method to obtain magnetic aqueous ink composition for MICR (Magnetic Ink Character Recognition) ink jet printing comprising an aqueous dispersion of functionalized magnetic nanoparticles, humectant agents, solvents, biocide and water. It also allows obtaining stable inks for long periods with extremely high concentrations of magnetic nanoparticles with loading between 15% and 40% by mass and magnetic signals varying from 80 to 200%. Through the use and special combination of humectant agents, the present inventions increase the print head protection, by decreasing abrasiveness and increasing fluidity. The resulting ink has superior printing quality and increased service life of the printing system.
Identify the most important claim in the given context and summarize it
[ "BACKGROUND OF THE INVENTION [0001] This request is, in parts, a continuation of the U.S. Pat. No. 8,815,393 B2, “Process for obtaining functionalized nanoparticulate magnetic ferrites for easy dispersion and magnetic ferrites obtained through the same”", "which derives from the Brazilian patent application, PI 1002273-2, “Processo de obtenção de ferritas magnéticas nanoparticuladas e funcionalizadas para fácil dispersão e ferritas magnéticas obtidas através do mesmo.”", "That patent, from the same company (Nanum Nanotechnology SA) and from the same inventors, describes a novel process to produce nanoparticle magnetic ferrites and its dispersions, also known as ferrofluids, for various applications mentioned therein, including the production of magnetic inkjet inks.", "The present invention presents in detail the process to transform the innovative water based magnetic dispersion described in that patent into innovative water based magnetic inkjet ink for MICR (Magnetic Ink Character Recognition) applications.", "[0002] Technologies for inkjet printing and the production of inkjet inks have been around for several decades.", "They contain, in general, dyes and/or pigments, surfactants, humectants, biocides, among others.", "The inkjet ink formulation also requires very specific situations in terms of viscosity, surface tension, drying rates, etc.", "Similarly, magnetic MICR printing technologies have decades of evolution involving the particles and the physical and magnetic characteristics thereof.", "[0003] The technology to produce water based magnetic inkjet ink for MICR applications usually can be divided into two consecutives and interdependent processes.", "The first one is the manufacture or suspension (by dispersing, milling, etc) or adjustment of the magnetic particles in a stable aqueous dispersion (ferrofluid) with a high solids concentration, always higher than the final ink.", "The second one is the ink formulation directed to the specificities of inkjet printing technologies.", "The two main digital print technologies are thermal and piezoelectric, which may happen by continuous flow (bulk) or by cartridges with defined volumes.", "These printing characteristics define the physicochemical properties that the ink should have during the printing process such as dynamic viscosity, surface tension and evaporation during the drop formation, and the drying speed and the characteristic of the ink penetration into the substrate after drop formation.", "The ink formulation results in the setting of these parameters and is closely linked to the characteristics of the initial dispersion and its stability.", "[0004] One of the main challenges of magnetic ink jet printing technology is that the cartridge nozzles are extremely small, on the order of 1 μm in diameter maximum, requiring then magnetic pigments of sub micron order to avoid clogging.", "Since the magnetic signal response is proportional to the particle size and its mass, the other challenge is to achieve a stable dispersion for high concentrations of pigments, in such a way that in a single printing process the magnetic signal reaches the intensity required for MICR readers available on the market.", "Typically, concentrations between 15% and 35% are used in standard MICR ink on the market.", "Such pigment concentration becomes detrimental to the orifices of the print head of ink jet system due to their rheological characteristics, such as high viscosity and high drying rate making the shear stress a factor of great importance.", "Furthermore, these pigments may consist of considerable hardness materials where the print head damage due to their abrasiveness should be considered.", "SUMMARY OF INVENTION [0005] The present invention starts from an innovative process to obtain a water-based dispersion with high stability, based on strong chemical bonds as opposed to other technologies that use chemical interactions only, such as Van der Waals forces, to maintain the stability of the dispersion, which means, long range forces much weaker than chemical bonds.", "These interactions are obtained using coatings, surfactants, etc.", "as opposed to use an initial surface treatment of the magnetic particles with subsequent chemical binding of a selected compound (functionalizer) which will be responsible to also interact with water.", "We call this process as functionalization.", "[0006] The magnetic particles production and its water based ferrofluid (or aqueous dispersion) is already discussed in great detail at the U.S. Pat. No. 8,815,393 B2 as well as its process and its differentiation in relation to other existing patents.", "We add on this request some other quotes that drive the title of the invention and the specific claims for aqueous MICR printing inks in inkjet printers.", "[0007] The patents of Xerox Corporation U.S. Pat. No. 8,409,341 B2 and U.S. Pat. No. 8,597,420 B2 include MICR inks for inkjet printing, but are specific to solvent-based ink formulations.", "On the other hand, the U.S. Pat. No. 8,236,192 B2 includes water based formulations too.", "They are inks based on single crystals of stabilized magnetic nanoparticles, single crystals containing domains at least 10 nm, and the absolute value of magnetic anisotropy greater than or equal to 2×10 4 J/m 3 .", "These simple magnetic crystals are composed of at least one metal nanoparticle involving Fe, Co or Mn.", "Such nanoparticles may also be bimetallic or trimetallic selected from the following group of choices FePt, CoPt, MnAl, MnBi, CoO.", "Fe 2 O 3 and BaO[.", "].6Fe 2 O 3 , plus Fe and Co. Intervals of remanence, coercivity and magnetic moment of saturation are set for them.", "Several ink compositions are disclosed, primarily for nonpolar carriers where dyes, resins and surfactants are added.", "For aqueous dispersions, anionic surfactants and other ingredients are added while the particles are milled with ball mill for several hours.", "[0008] The present invention differs from Xerox technology in various aspects.", "First, it is a water borne dispersion, which precludes any similarity to the first two Xerox quotes that are based on non-polar solvents.", "In the third Xerox patent, U.S. Pat. No. 8,236,192 B2;", "all of the magnetic pigment dispersions undergo a process of comminution, by milling or using high shear rate mixers.", "Furthermore, the stabilization of the particles does not occur with a functionalization of them, as well as discussed in the example below.", "[0009] The Nu-Kote International, Inc. patents, number U.S. Pat. No. 6,746,527 B1;", "U.S. Pat. No. 6,767,396 B2 and U.S. Pat. No. 6,726,759 B2 deal with the compositions of aqueous inks for inkjet MICR printing using metal oxides.", "The particles or the metal oxide pigments should have a size less than 0.5 microns and remanence of at least 20 emu/g.", "One such patent (U.S. Pat. No. 6,767,396 B2) teaches us about the preparation of the possible metal oxide pre-dispersions as a basis for the formulations of the claimed MICR inks.", "In all cases the pre-dispersions start with the mixture of water with at least one surfactant and will slowly by adding the magnetic powder pigment, or the metal oxide particles selected from specified groups.", "This magnetic pigment can also be made of metal oxide particles coated with hydrophilic inorganic silicates such as aluminum silicate, sodium silicate and potassium silicate.", "Once ready these pre-dispersions a sequence of grinding processes and filtration begin, conventional and/or unconventional, in order to mix the ink and further reduce the particle size.", "The other two Nu-Kote patents (U.S. Pat. No. 6,726,759 B2 and U.S. Pat. No. 6,746,527) seek to be wider in the previous patent requested claims increasing the list of surfactant possible to use.", "The same applies to the materials for the hydrophilic coating dispersion in the wet cake form, the metal oxide used and its remanence intervals.", "Also extend to the composition of the final ink produced from these pre-dispersions working with dyes and aqueous solvents.", "[0010] About the pre-dispersion, Nu-Kote technology uses a process typically classified as “top-down”, in which sub-micrometer metallic oxide particles are crushed and filtered while interacting with aqueous base containing a surfactant or a combination of them.", "At this stage the particles have already some differences, especially regarding the shape of the particles size distribution curve, besides that on the present invention the magnetic metal oxides particles are chemically synthesized by precipitation, classifying the case as “bottom-up.”", "However, it is in the dispersion technology and in the stabilization of these dispersions that the distance to the present invention provokes most of the differences.", "Inks originating from each of the technologies will exhibit quite different rheological characteristics and formulations.", "[0011] The pre-dispersions are very distinct from the present invention.", "All teaching and claims of Nu-kote revolves around the basic need to use a surfactant or a combination thereof throughout the process to ensure the stability of the aqueous dispersion, while dispersion in the present invention is independent of the surfactant in such a way that even if it is added subsequently to ink formulation in small quantity it will act only as a corrective surface tension, not to stabilize the dispersion of magnetic pigment.", "The Nanum keeps in its laboratory one of its first aqueous magnetic dispersions produced in September 2009 where no surfactant was added.", "After several years dispersion remains stable, although part of the water has evaporated and the solid concentration which was originally 50% being currently around 65%.", "This distinction can also be observed easily by noting that even with solids concentrations as high as 65% dispersion of the present invention further presents its fluid character, while the patent Nu-kote to work with concentrations around 58% was classified as paste (wet cake form).", "[0012] Although the coating process is quite different from the functionalization process of the magnetic particles used at the present invention, Nu-kote technology may alternatively use hydrophilic compounds to obtain coated particles.", "The compounds listed for the coatings are aluminum silicates, inorganic silicates, metal stearates, ester metal phosphates, metal sulfonates, and the like, where no such compounds are used in the functionalization process of the present invention.", "[0013] It is also possible to perform an estabilization of two layers made according to the teachings of Shimoiizaka et al.", "(U.S. Pat. No. 4,094,804) in which the oleic acid is used as the first functionalizing layer, by chemical bond, creating the connections between the particles and unsaturated fatty acids in the second layer, by long range interactions.", "Thus, the aqueous dispersion of Shimoiizaka always happen in the presence of this second component, which now acts as a recoating which will be limited by physical adsorption of the second layer, thereby compromising the stability of the dispersion with a weaker bond, as described by himself (col 3-ln 45).", "[0014] The technology route taught here uses a single layer of functionalizing strongly attached to the particle via chemical bonds.", "Thus, with more flexibility, for polar bases we can choose between amino acids, tartaric acid, citric acid or oxalic acid.", "This step is preceded by attack on the surface by using mineral acids (instead of organic acids such as oleic acid) or strong bases, depending on the particle composition.", "As these processes will release various ions in the solution, a washing process becomes very important in this technology to remove ions and other salts, which can block the particle surface or contribute to the instability of the same system due to the increased conductivity.", "In the Shimoiizaka process the particles can not and is not washed at this point, because such process could lead to losses of part of the surfactant loosely bound to the outer layer.", "[0015] Having this unique dispersion, super stable in aqueous basis, the present invention solves MICR printing ink formulation relatively simple and uncomplicated, requiring only the adjustments of viscosity, surface tension, drying time, and biocides, depending on the printing technology and substrates to be considered.", "One of the most important and necessary characteristics in the ink formulation of the present invention is the use of special humectant compounds to ensure the moist property of the printing head surface having an ink with high solids concentration, but also to avoid the accumulation of material after the jetting, avoiding the impregnation of organic and inorganic part and leaving the printing head clean and unblocked.", "From the large amount of existing humectant compounds the polyols which exhibit excellent performance for this technology are bis-(cyanoethyl)-dihydroxypropylamine (known as “C-1”), bis-(2-hydroxyethyl) glycolamide (known as “BHEGA”), bis-(hydroxyethyl)-lactamide (known as “BHELA”) and bis-(hydroxyethyl) dimethyl hydantoin (referred to as “DANTOCOL EHD”).", "[0016] The most interesting of the present invention is that the nanostructure formed by the nano composite magnetic pigment, their water based functionalizer and humectant compounds create a unique system that reduces the dispersion shear stress with greater fluidity and low abrasiveness, preserving the printhead of the inkjet printer.", "AIM OF THE INVENTION [0017] The main aim of this invention is to provide a method of obtaining magnetic water based inks to jetprint MICR (Magnetic Ink Character Recognition) starting from dispersions of functionalized magnetic ferrites nanoparticles, obtained according to U.S. Pat. No. 8,815,393 B2.", "Some of these dispersions are already available in the global market being offered by the Nanum Nanotecnologia SA, such as Nanumadit AT-0701, AT-0716, AT-2701, AT-2801, etc.", "[0018] Another aim of the present invention is the production of aqueous MICR inks with extremely high concentrations of magnetic nanoparticles with loading between 15% and 40% by mass, keeping them stable for several months and creating a system that protects the printhead of inkjet cartridges against the effect of high ceramics load, having less abrasiveness and greater fluidity.", "DESCRIPTION OF THE DRAWINGS [0019] FIG. 1 : hydrodynamic size distribution of particles, by the technique of Dynamic Light Scattering (DLS) of Nanumadit NA-0701 additive.", "DETAILED DESCRIPTION OF THE INVENTION [0020] To obtain aqueous MICR inks for inkjet printing starts from aqueous dispersion of functionalized nano-sized magnetic ferrite produced according to the process described in U.S. Pat. No. 8,815,393 B2.", "Nanometrics, simple or compound magnetic ferrites are chemically synthesized by co-precipitation where their physical and magnetic characteristics can be adjusted as needed.", "These adjustments are possible by modifying the composition of the metal oxide according to the following criteria for simple ferrite (MFe2O4 or MFe12O19) or for compound ferrites (N×M(1-x)Fe2O4 or N(1-y)Mx+YFe(2-x)O4, for example) where M and N can be metal atoms such as Sm, La, Bi, Ba, Mo, Sr, Ni, Co, Fe, Mn, Cr, etc.", "These ferrites exhibit a particle size distribution ranging from 15 to 300 nm, preferably between 15 and 120 nm, as shown in FIG. 1 below, with a surface area between 10 and 120 m2/g, preferably between 25 and 90 m2/g.", "Presenting also magnetic saturation between 05 and 80 emu/g, magnetic remanence ranging from 1 to 60 emu/g magnetic coercivity of from 10 to 3000 Oe, a magnetic saturation, preferably between 30 to 80 emu/g, magnetic remanence from 10 to 30 emu/g, and magnetic coercivity between 200 and 800 Oe.", "[0021] The following Table 1 shows some practical results: [0000] TABLE 1 Magnetic properties of the additives used in the MICR ink production.", "Hc Mr Ms Nanumadit (Oe) (emu/g) (emu/g) Composition NA-2601 34 3 55 Manganese, Boron ferrite NA-2701 724 4 15 Barium, Cobalt ferrite NA-2801 553 15 41 Cobalt.", "Cerium ferrite NA-0701 347 19 62 Manganese, Cobalt ferrite NA-2901 238 14 54 Manganese, Gadolinium, Cobalt ferrite NA-3001 1201 25 42 Barium ferrite Hc: coercive field, Mr: remnant magnetization, Ms: saturation magnetization [0022] After this co-precipitation process, a surface treatment of the particles occurs with the addition of a strong acid or base solution, followed by a first wash, thereby preparing the material for functionalization.", "The functionalization for aqueous base can be accomplished with a functionalizer, or a combination thereof, chosen from oxalic acid, citric acid, tartaric acid and amino acids.", "The material obtained by the functionalization with adjusted pH is then washed again.", "This second wash may occur by filtration, dialysis and/or decantation mixing water and organic solvents.", "So far all follow the procedures set forth in U.S. Pat. No. 8,815,393 B2 and the resultant ferrofluid with solids concentration between 35% and 55%, preferably 50%, is directed to the manufacture of ink without the necessity of transformation into a powder.", "Some weak agglomeration may occur at this time, particularly if the ferrofluid is stored for a long period, and in this case, a physical deagglomeration action can occur, such as a gentle grinding to not damage the particle/functionalizing system.", "Preferably the deagglomeration is done by ultrasound.", "In general, the ferrofluid, the standard dispersion to produce MICR ink for ink jet printing has the following characteristics: viscosity between 40 and 400 cP for a suspension of 50% m/m and a pH between 5 and 8.", "In Table 2, below shows practical results of these Nanum dispersions that are already in the market.", "[0000] TABLE 2 Physical and chemical properties of magnetic additives used in MICR ink production.", "Viscosity Nanumadit (cP) pH NA-0701 150-200 6.5-7.0 NA-0716 350-400 7.0-8.0 NA-2701 300-380 6.5-7.0 NA-2801 250-350 6.5-7.0 [0023] In general, the requirements for an adequate MICR ink is to have good print quality, stability, do not cause printhead clogging, good magnetic reading, low kogation, and longprinting decap time.", "The quality of ink printing includes good definition of the printed characters, driven mainly by the physicochemical characteristics of it, such as viscosity and surface tension.", "The stability of the ink is closely linked to the stability of the dispersion and the dispersion with the mixing of other solvents, thus other solvents which comprises the ink cannot destabilize the initial dispersion.", "The ink destabilization leads to clogging of the of the printhead nozzles.", "Another cause of clogging of these orifices is any failure in the process that allows, for example, contamination by dust or other materials.", "Typically, all the ink undergoes a final filtration process with filter elements of 0.2 microns to guarantee this does not cause clogging.", "[0024] In addition, another major cause of clogging and printing failure is the drying of ink or the deposition of decomposed ink through the nozzles (kogation).", "It is necessary to balance the ink drying time in such a way that as soon as the ink jet exits the nozzles, ink blots and scattering does not occur in the already printed substrate and this variable also depends on the printer technology and printing speed.", "Thus, it is common to use specific and adapted inks to the various printheads and inkjet technologies (thermal, piezoelectric, etc.).", "This need for fast ink drying on the substrate also leads to the drying of the ink at the edge of the print nozzles when printing stops.", "In the return of the activities the dry film should be quickly and completely eliminated to avoid compromising the next print quality, so get a good printing decap time is also key.", "To analyze and monitor the behavior of the ink decap time and kogation 25 cm solid-fill printing evaluations are performed on the time of the cartridge filling and then after resting for 5 minutes, 30 minutes, 1 day, 7 days and 30 days with no external device that stimulates jetting.", "In none of these cases the print quality may be compromised.", "[0025] With the dispersions based on functionalized nanoparticles, key feature of this technology presented here, the stability of the ink is not a problem and all eyes are basically focused on print quality, drying time, kogation and decap time.", "[0026] The production of the MICR ink starts by the manipulation of other solvents (such as -pyrrolidone, n-methyl-pyrrolidone, buthyldiglycol, etc) that comprise the aqueous base and will receive the generated or previously acquired magnetic dispersion.", "The solvents on this technology contain polyols and other humectants which influence the drying time, penetration of the ink into paper or other substrate, and decap time.", "From the large amount of existing polyols and other humectants compounds which exhibit excellent performance for this technology the preferred are glycerin, diethylene glycol, polyethylene glycol, etilenoglicolmonoetileter, sorbitol, mannitol, glicereth bis-(cyanoethyl)-dihydroxypropylamine (known as “C-1”), bis-(2-hydroxyethyl) glycolamide (known as “BHEGA”), bis-(hydroxyethyl)-lactamide (known as “BHELA”) and bis-(hydroxyethyl) dimethyl hydantoin (referred to as “DANTOCOL EHD”).", "[0027] Immediately after homogenizing the aqueous ink base it is added a sufficient amount of the magnetic dispersion (Nanumadit) and new mixing is processed.", "Depending on the print head and jet firing technology, wetting agents are added to adjust the surface tension, as well as biocides.", "The ink is then filtered and is ready for storage, supply cartridges, shipment, etc.", "[0028] In general, the MICR inks are characterized by viscosity up to 18 cPs, a density between 1.2 and 1.7 g/cm 3 , surface tension between 25 and 55 dyne, conductivity between 500 and 1000 μS·cm-1, neutral pH (˜7), particle size smaller than 200 nm and magnetization between 80% and 200% as measured, for example, using the MICR Qualifier equipment from the RDM Corporation.", "[0029] Following are examples of the process and products claimed: Example I [0030] The formula is manipulated by homogenization of components forming the basis of the ink which is aqueous.", "To ensure humectation, decap time and printing head protection diethylene glycol (2%), glycerin (1%) and Dantocol DHE (3%) are added plus 2-pyrrolidone (5%) and butyldiglycol (1%) for drying.", "Besides influencing the drying time, 2-pyrrolidone improves print quality and butyldiglycol allows greater penetration of the ink into the paper.", "Water completes the base formulation with 28%.", "The rest 60% is the ferrofluid Nanumadit NA-0701, synthesized such as described in U.S. Pat. No. 8,815,393 B2 and added in a second step.", "In this formulation ferrofluid contains 50% of solids and is comprised of a cobalt and manganese ferrite functionalized with citric acid using water as the carrier.", "The ink base plus the ferrofluid is now homogenised for 60 minutes at 230 rpm without heating.", "biocide was added to control the growth of microorganisms.", "This ink has for example printed using HP122 cartridge reaching average magnetization of 110% using IDAutomationSCMC7 source;", "size 12;", "and paper weights of 120 g/m 2 .", "Example II [0031] In this other formulation, also aqueous, it is added glycerin (7%), BHELA (5%) and polyethylene glycol 6000 (2.5%).", "Water completes the base formulation with 21.5%.", "After homogenization the base is added to the magnetic loading (64%)—Nanumadit 0701.", "Mixing is carried out for 60 minutes more at 230 rpm without heating.", "The ink is then filtered through 0.5 μm absolute filter.", "Wetting agents and biocide were added to adjust the surface tension of the cartridge in the acceptable range and control the growth of microorganisms.", "This formulation has been developed for high-speed printers with piezo printhead, such as Kyocera KJB4 printhead.", "Example III [0032] Another formulation was developed using now Nanumadit NA-0716 additive.", "It was mixed for humectation diethylene glycol (2%), glycerin (2%) and C-1 (5%) and 2-pyrrolidone (10%) for drying, and print quality.", "Water is added (26%) to complete the base formulation.", "In a second step it was added the magnetic loading (55%)—0716 Nanumadit synthesized according to U.S. Pat. No. 8,815,393 B2.", "In this formulation the ferrofluid contains 50% solids and is comprised of a cobalt and manganese ferrite functionalized with histidine using water as the carrier medium.", "Homogenization is carried out for 60 minutes at 230 rpm without heating.", "Wetting agents and biocide were added to adjust surface tension and control the growth of microorganisms.", "This ink was printed using HP45 cartridge reaching average magnetization of 150% using IDAutomationSCMC7 source;", "size 12;", "and paper weights 90 g/m2.", "Example IV [0033] This aqueous base formulation was prepared with the additive Nanumadit NA-2701.", "For the base of the ink were mixed glycerol (7%), Dantocol DHE (5%), 2-pyrrolidinone (7%), Cab-o-jet 300 (10%) and water (11%).", "In a second step it was added the magnetic loading (60%)—2701 Nanumadit synthesized as described in U.S. Pat. No. 8,815,393 B2.", "In this formulation ferrofluid contains 50% solids and is comprised of a cobalt ferrite and barium functionalized with citric acid using water as the carrier medium.", "The homogenization was performed during 60 minutes at 230 rpm without heating.", "The ink was filtered through 0.2 μm absolute filter.", "Wetting agents and biocide were added to adjust surface tension and control the growth of microorganisms.", "This formulation was developed for high-speed printers with piezo print head, such as the Ricoh Gen4 head.", "Example V [0034] Another aqueous formulation was prepared using the additive Nanumadit NA-2801.", "Diethylene glycol (1%), glycerin (1%), polyethylene glycol 600 (1.5%), Dantocol DHE (3%), 2-pyrrolidone (5%), butyl diglycol (0.5%) and water (38%) were mixed to form the base of the ink.", "In a second step was added the magnetic loading (50%)—Nanumadit 2801, synthesized as disclosed in U.S. Pat. No. 8,815,393 B2.", "In this formulation ferrofluid contains 50% solids and is comprised of a cobalt and cerium ferrite functionalized with citric acid using water as the carrier medium.", "Homogenization is carried out for 60 minutes at 230 rpm without heating.", "Wetting agents and biocide were added to adjust surface tension and control the growth of microorganisms.", "This ink was printed using HP45 cartridge reaching average magnetization of 100% using IDAutomationSCMC7 source;", "size 12;", "and paper weights 140 g/m 2 .", "Example VI [0035] For the base of this ink formulation were mixed diethylene glycol (1%), glycerin (2%), BHELA (4%), n-methylpyrrolidone (8%) and water (25%).", "In a second step the magnetic loading was added (60%)—2812 Nanumadit synthesized as described in U.S. Pat. No. 8,815,393 B2.", "In this formulation ferrofluid contains 50% solids and is comprised of a cobalt and cerium ferrite functionalized with tartaric acid using water as the carrier medium.", "The homogenization was performed during 60 minutes at 230 rpm without heating.", "The ink was first filtered through a 1.0 μm nominal filter and an absolute filter followed by 0.5 μm.", "Wetting agents and biocide were added to adjust surface tension and control the growth of microorganisms.", "This ink was printed using HP45 cartridge reaching average magnetization of 120% using IDAutomationSCMC7 source;", "size 12;", "and paper weights 90 g/m 2 ." ]
RELATED APPLICATION This application is a divisional of U.S. patent application Ser. No. 11/263,184, filed Oct. 31, 2005 entitled “Method of and Apparatus for Classifying Arrhythmias Using Scatter Plot Analysis”, now U.S. Pat. No. 7,657,307, herein incorporated by reference in its entirety. FIELD OF THE INVENTION Most of the embodiments of the disclosure relate generally to a method of classifying arrhythmias in implantable medical devices, and more particularly, to a method and apparatus for discriminating atrial fibrillation from atrial flutter using a measure of variability of a cardiac rhythm parameter. BACKGROUND A variety of techniques have been developed for collecting and interpreting data concerning the electrical activity of the heart. Some techniques use external medical devices (EMDs) in the clinical setting, and others use implantable medical devices (IMDs). Implantable cardiac monitors, such as the MEDTRONIC® Reveal™ insertable loop recorder, have also been developed and clinically implanted that employ the capability of recording cardiac electrogram (EGM) data for subsequent interrogation and uplink telemetry transmission to an external programmer for analysis by a medical care provider. The recorded data may be retrieved using an external programmer operated by a medical care provider. The programmer may include the ability to display the retrieved EGM data and/or perform processing and analysis functions on the retrieved EGM data. Stored segments of data can be transmitted via telemetry transmission to an external device for further analysis when a telemetry session is initiated. Aspects of the Reveal™ insertable loop recorder are disclosed in commonly assigned PCT publication WO98/02209 and in U.S. Pat. No. 6,230,059, the disclosures of which are hereby incorporated by reference in their entirety. Scatter-plots, sometimes referred to as Lorentz or Poincaré plots, have been used to plot EGM and electrocardiograph (ECG) data. For example, U.S. Pat. No. 5,622,178 issued to Gilham describes a system and method for dynamically displaying cardiac interval data using scatter-plots. Consecutive R-R intervals form a coordinate pair (e.g., the “x” and “y” coordinates) of a point that is plotted on the scatter-plot. Subsequent points are plotted by “sliding” one heartbeat to the next group of successive heartbeats (i.e., the second, third, and fourth heartbeats) and plotting the next pair of R-R intervals. FIG. 1 illustrates an example of this technique in plotting R-R interval data on a scatter plot. Such scatter-plots may provide a visual indication of the variability of the parameter plotted. Published Patent Application No. 2002/0065473 compares a number of consecutive R-R interval differences with a predetermined value to measure ventricular rate stability as part of a method to detect atrial fibrillation. A counter is incremented every time the measured R-R interval difference exceeds a threshold value, and classifies a rhythm as AF when a threshold total number is reached. Published Patent Application No. 2004/0092836 discloses an AF detection algorithm that uses a Cluster Signature Metric (CSM) that is based on the two-dimensional distribution of “first order lag” of R-R interval differences. Each of the above references is incorporated by reference herein in its entirety. In atrial fibrillation (AF), the atria depolarize at an elevated rate that is highly irregular. The irregular nature of the ventricular response during AF is characterized by fluctuations in the intervals between ventricular contractions. In atrial flutter (AFL), the atria beat at an elevated rate that is highly regular, and a certain portion of the atrial depolarizations may be conducted to the ventricles in a predictable pattern. There are many instances where it is desirable to be able to diagnose intermittent spontaneous cardiac arrhythmias, particularly AF and AFL, in ambulatory patients. Atrial rate may serve as a criterion for distinguishing between AFL and AF. For example, AFL (types I and II) may typically occur at rates that can range from about 220 to about 450 bpm, and AF typically occurs at rates greater than about 300 bpm. However, since a significant range of overlap exists between AF and AFL, and since the range of overlap may be even greater in patients taking anti-arrhythmic drugs and/or in elderly patients, a method of distinguishing them that does not rely solely on rate is needed. A method and system for performing scatter-plot analysis to classify cardiac rhythms is desired which minimizes computational resource requirements and allows for real-time processing of cardiac signals. A method of using such real-time data to affect therapy selection decisions (e.g., by an IMD) is also desirable. SUMMARY OF THE INVENTION In certain embodiments of the invention, a method of classifying arrhythmias includes the steps of acquiring a cardiac signal; deriving a recurring cardiac rhythm parameter from the cardiac signal and storing the information derived as a series of values; plotting a point on a scatter plot for each pair of successive stored values, the abscissa of each plotted point being equal to a first value of a pair of successive stored values, and the ordinate of each plotted point being equal to a second value of the pair of successive stored values, the scatter plot being divided into a plurality of regions; deriving a measure of variability by counting the number of regions in which one or more points are plotted; and comparing the measure of variability to a threshold value to classify the rhythm. In certain other embodiments of the invention, a system for classifying arrhythmias includes a sensor for acquiring a cardiac signal; a processor for deriving a recurring cardiac rhythm parameter from the cardiac signal and storing it as a series of values; a database for plotting a point on a scatter plot for each pair of successive stored values, the abscissa of the point being the first of a pair of successive stored values, and the ordinate of the point being the second of the pair of successive stored values, and wherein the scatter plot is divided into a plurality of regions; a processor for deriving a measure of variability by counting the number of regions in which one or more points are plotted; and a comparator for comparing the measure of variability to a threshold to classify the rhythm. In another embodiment of the invention, an implantable medical device for classifying arrhythmias includes sensing means for acquiring a cardiac signal; processing means for deriving a recurring cardiac rhythm parameter from the cardiac signal and storing it as a series of values; plotting means for plotting a point on a scatter plot for each pair of successive stored values, the abscissa of the point being the first of a pair of successive stored values, and the ordinate of the point being the second of the pair of successive stored values, and wherein the scatter plot is divided into a plurality of regions; a processor for deriving a measure of variability by counting the number of regions in which one or more points are plotted; and a comparator for comparing the measure of variability to a threshold to classify the rhythm. DESCRIPTION OF THE DRAWINGS FIG. 1 is an example of a scatter plot of R-R interval data. FIGS. 2 ( a )-( c ) illustrate a cardiac signal and various cardiac rhythm parameters derived therefrom. FIGS. 3 ( a ) and ( b ) illustrate a cardiac signal and a scatter plot derived therefrom in accordance with an embodiment of the invention. FIGS. 4 ( a )-( c ) are examples of alternate embodiments of a scatter plot in accordance with embodiments of the invention. FIG. 5 is a scatter plot of a cardiac rhythm parameter, the plot having a plurality of regions formed by a linear grid pattern in accordance with an embodiment of the invention. FIG. 6 is a scatter plot of the data shown in FIG. 5 , the plot having a plurality of regions formed by a logarithmic grid pattern in accordance with an embodiment of the invention. FIG. 7 is a flowchart showing the steps in a process of calculating a measure of variability from a scatter plot in accordance with an embodiment of the invention. FIG. 8 is a plot of a measure of variability as a function of time in accordance with an embodiment of the invention. DETAILED DESCRIPTION The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings depict selected embodiments and are not intended to limit the scope of the invention. It will be understood that embodiments shown in the drawings and described below are merely for illustrative purposes, and are not intended to limit the scope of the invention as defined in the claims. FIGS. 2( a )-( c ) show examples of various cardiac rhythm parameters derived from a cardiac signal 20 . Cardiac signal 20 may be acquired from an ECG recording or from an EGM signal, for example. Acquiring a cardiac signal from an ECG recording may, for example, include recording electrical signals from sensors (surface leads) placed on the skin of a patient as is known in the art. Acquiring a cardiac signal from an EGM signal typically includes recording electrical signals from one or more sensors (leads) implanted in a patient either within or in relative close proximity to a chamber of a heart. EGM signals may be far-field, showing timing and morphological information associated with the entire heart, similar to that shown by an ECG, or they may be near-field, showing timing and amplitude information of a single area or chamber of the heart. One cardiac rhythm parameter often used to analyze heart rhythms is the R-R interval 2 , as shown in FIG. 2( a ). Also shown in FIG. 2( a ) is an R-R interval 3 between a “normal” R-wave and a PVC 5 . The R-R interval is an example of a recurring cardiac rhythm parameter, since it can be derived or measured on a repeating basis. Other recurring cardiac rhythm parameters that may be useful for analysis include, but are not limited to, the following examples: P-P interval 4 , R-wave amplitude 7 , P-wave amplitude 8 , Q-T interval 11 , and R-wave slope 6 , as shown in FIGS. 2( a ) and ( b ). FIG. 2( c ) shows one example of a recurring cardiac rhythm parameter, ΔR-R interval 9 , that may be derived from another recurring cardiac rhythm parameter (in this case, from the R-R intervals). Another recurring cardiac rhythm parameter that may be derived from R-R intervals is ventricular rate. Ventricular rate, for example, may be calculated as a function of the R-R interval 2 , using the equation: Rate vent (bpm)=60,000/(R-R Interval, msec). One of ordinary skill in the art would appreciate that other recurring cardiac rhythm parameters may be similarly derived from a cardiac signal 20 and used in accordance with embodiments of the invention, and would therefore fall within the scope of the claimed invention. FIG. 3( b ) shows an example of a scatter plot 10 derived from the cardiac signal 20 shown in FIG. 3( a ). A series of cardiac rhythm parameters 16 , such as R-R intervals, may be derived from the cardiac signal 20 as described above. The scatter plot 10 is formed by plotting points 14 thereon. Each point 14 is characterized by an x-coordinate (abscissa 22 ), and a y-coordinate (ordinate 24 ), as shown. Note that FIG. 3( a ) may only show a portion of the cardiac signal 20 corresponding to scatter plot 10 in FIG. 3( b ), since FIG. 3( a ) is a time plot of cardiac signal 20 , and since FIG. 3( b ) is a scatter plot 10 which condenses a large number of points 14 (N=100) corresponding to a large number of R-R intervals into a relatively small plot area. To illustrate the plotting of points 14 onto a scatter plot 10 , the series of R-R intervals shown in FIG. 2( c ) may be plotted based upon pairs of R-R intervals 31 - 37 as follows: A first point may have an abscissa of 700 msec and an ordinate of 750 msec corresponding to the first pair of R-R intervals 31 , 32 . A second point may have an abscissa of 750 msec and an ordinate of 720 msec corresponding to the second pair of R-R intervals 32 , 33 . Third and subsequent points are plotted following this same pattern. It should be noted that the choice of abscissa as the first value of each pair of values, and of ordinate as the second value of each pair of values, is somewhat arbitrary; the order could be reversed and would provide an equivalent result without departing from the scope of the invention. See FIG. 1 . The area of the scatter plot 10 is divided into a plurality of regions 12 . Each region 12 occupies a specified area of scatter plot 10 , as shown in FIG. 3( b ). Each point 14 is plotted into one region 12 of the scatter plot 10 . This may necessitate the creation of a rule for determining which region 12 a point 14 falls within in situations where the point 14 is plotted exactly on the boundary between two regions 12 . One such rule may simply be a “round up” rule, whereby a point 14 that falls exactly on a boundary between regions 12 is assigned to the “higher-valued” region, for example up and/or to the right in the scatter plot 10 shown in FIG. 3( b ). FIGS. 4 ( a )-( c ) are examples of alternate configurations of regions 12 having a shape that is not rectangular, and which occupy generally curved portions of the scatter plot 10 in accordance with various embodiments of the invention. Note that the size and shape of region 12 can also vary to suit a particular application. For example, the axes of scatter plot 10 need not be linear. FIGS. 5 and 6 , for example, show the same data plotted on scatter plots having linear and logarithmic axes, respectively. The determination of a measure of variability of a cardiac rhythm parameter is based on a graphical estimation using a region counting algorithm, as explained below. In FIG. 3( a ), the irregular heart rhythm (cardiac signal 20 ) is plotted in scatter plot 10 of FIG. 3( b ) based on a sequence of successive values of a cardiac rhythm parameter 16 derived from the cardiac signal 20 . A specified number of plotted points (the “window” of plotted points) is shown plotted using the Lorentz (or Poincaré) scatter-plot technique described above. The window may, for example, be a sliding window of N points, which slides one point at a time. With a sliding window, each additional heartbeat causes a new point to be plotted, and the oldest point to be removed, so that the total number of points plotted remains equal to the window size, N. Of course, the sliding nature of the window does not have to be updated with each additional heartbeat; a window of N points could be plotted at periodic intervals, for example, with or without overlap between successive windows. With continued reference to FIG. 3( b ), scatter plot 10 is shown divided into a plurality of regions 12 . The regions 12 shown in the particular embodiment of FIG. 3( b ) are comprised of rectangular boxes forming a grid pattern throughout the area of scatter plot 10 . As noted above, the regions 12 need not be rectangular or square in shape. The axes of scatter plot 10 shown FIG. 3( b ) range from 150 min −1 to 400 min −1 in a linear grid plot, reflecting a range of atrial rates (which may be derived from P-P intervals, for example). It should be noted that the axes of scatter plot 10 need not be linear, nor does it need to reflect rate or interval information. EGM slope and amplitude are examples of other cardiac rhythm parameters that may also be plotted, among other possible cardiac rhythm parameters. FIGS. 5 and 6 reflect the same cardiac rhythm parameter data plotted on linear and logarithmic scatter plots, respectively. To provide a measure of the variability of the cardiac rhythm parameter being plotted, a count is made of the number of regions 12 in which at least one point is plotted. Thus, the variability of the cardiac rhythm parameter may be represented as a number, equal to the number of regions counted containing one or more plotted points. Optionally, the variability may be expressed as a percentage, for example: Variability=[# regions with at least 1 point/ N points]×100%  Eqn 1 or Variability=[# regions with at least 1 point/total # regions]×100%.  Eqn 2 In one embodiment of the invention, the counting of regions containing one or more plotted points may be weighted by using a weighting factor. For example, in certain embodiments of the invention, it may be desirable to discount the effect on variability of points that fall in regions that are very close to certain specified areas of the scatter plot (areas that tend to have a high concentration of points plotted therein, for example). It may likewise be desirable to increase the effect on variability of points that fall in regions that tend to have a low concentration of plotted points. Thus, a weighting factor may be assigned to each region based upon its location within the scatter plot to thereby affect the measurement of variability. FIG. 8 shows a plot of variability over time, with each point plotted corresponding to a measured value of variability (percentage variability is shown in FIG. 8 ). As noted above, each measured value of variability is calculated based upon a window of N points. The window may “slide” one point at a time, or may be based on windows of N points that are “staggered” from one another by a specified number of points or by a specified amount of time, for example. FIG. 8 indicates a threshold 40 (dashed line) for differentiating types of arrhythmias based upon the measure of variability. In some embodiments of the invention, additional thresholds (such as threshold 42 ) may also be used to further refine the arrhythmia classification. A measured variability that is above a specified threshold, for example, may be used to identify an atrial arrhythmia as AF rather than AFL. In one embodiment of the invention, rate information may be used in conjunction with a comparison of the measure of variability to a threshold. For example, an atrial rate of 350 bpm may be classified as either AF or AFL based on rate information alone. A variability that is above a specified threshold may indicate or confirm the presence of AF, while a variability that is below a specified threshold may indicate or confirm the presence of AFL according to certain embodiments of the invention. In FIG. 3( b ), 100 points are plotted in scatter plot 10 based upon a series of P-P intervals converted into atrial rate information in this example. Scatter plot 10 is divided into a plurality of regions 12 . In this particular example, the regions 12 are formed by grid lines arranged on scatter plot 10 such that the spacing between grid lines corresponds to a change in atrial rate of 16 beats per minute (min −1 ). Each region 12 therefore occupies a space of 16×16 min −1 . The number of regions 12 containing one or more plotted points 14 is then counted to obtain a measure of variability. In FIG. 3( b ), for example, a total of 33 regions 12 have one or more points 14 plotted therein. In percentage terms, the resulting measure of variability may be stated as 33%, since the total number of plotted points 14 is 100. The process followed in calculating the measure of variability is generally summarized in FIG. 7 , which defines the following steps: Choose a cardiac rhythm parameter (e.g., P-P interval). Select region size/shape and window size, N. Acquire and store cardiac rhythm parameter in a database. Plot cardiac rhythm parameter in a scatter plot until N points are plotted. Calculate measure of variability by counting the number of regions containing one or more plotted points. (Optional) Calculate percent variability. Compare variability to a threshold to classify the rhythm. (Optional) Repeat variability calculation over time. The variability of the cardiac rhythm parameter is determined by “drawing” a Lorentz plot of a number of preceding heart beats (window size) onto a scatter plot having a certain region or grid size and shape (resolution). Varying the window size and/or region size/shape may have an influence on the calculated variability. In FIG. 3( b ), a total of one hundred points 14 were plotted, corresponding to a window size (or width) of 100 (N=100). The choice of N may reflect a trade-off between the desire for calculational simplicity (or speed), and the desire for accuracy or stability. For example, a smaller window N may provide a result sooner (i.e., not as many beats are required, and less memory storage may be needed). A smaller window N may also reflect changes in the measured variability sooner, since the window will not be as heavily weighted with “old” plotted points 14 . A smaller window N may also tend to reflect information that is more local or transient in nature. A larger window N, by contrast, while possibly requiring larger memory storage and computational resources, may tend to produce a measured variability that is more “stable,” since it is “averaging” a larger quantity of data into a numerical result. A larger window may also tend to reflect information that is more global in nature. The “grid” (or region) resolution in the example of FIG. 3( b ) was based upon a linear, square-shaped region having 16×16 min −1 dimensions. The resolution may be affected by the choice of size and shape of the regions used. For example, a choice of larger regions may result in a smaller number of regions containing one or more plotted points, thereby resulting in a lower measure of variability, according to Eqn. 1. (Note: The variability measured by Eqn. 2 may be smaller, larger, or may be unaffected by changing the size of the regions.) Conversely, selecting smaller regions may result in more regions being counted, thereby producing a higher measure of variability, according to Eqn. 1. The selections of window size N and region size and/or shape may be affected by a variety of factors, such as the particular cardiac rhythm parameter being analyzed, patient history, known sensing issues (FFRWs, undersensing), etc. The selections regarding window size and region size/shape may also be affected by the rate/interval of the particular cardiac rhythm parameter or of the overall heart rate of the patient. In one embodiment of the invention, a calculation of rate/interval is made in conjunction with the variability measurement. The rate/interval may be an average rate based upon a certain number of beats, R; the number of beats R used to calculate rate may also be a parameter that can be selected and varied in accordance with certain embodiments of the invention. It should be noted that physically “drawing” or “plotting” the scatter plot 10 is not a required step. For example, the process of plotting points in a scatter plot may be performed by a memory device and logic circuitry and/or software instructions that are capable of identifying and recording which region 12 a point would fall into, and incrementing (and decrementing) counters to keep track of the points 14 that fall within each of the regions 12 . (Decrementing of a counter would occur, for example, when the sliding window of N points causes the oldest point 14 to be removed from the window, and hence, from the affected region 12 .) Each region 12 may, in such an embodiment, comprise a data bin for storing the number of points 14 that fall within a region, based on logic circuitry and counters, for example. Additional logic circuitry and/or a counter may determine the measure of variability by counting the total number of data bins that has one or more points stored therein. The methods of classifying arrhythmias disclosed herein are relatively simple to implement, and may be performed by an Implantable Medical Device (IMD). For example, the steps of plotting points and counting regions can be accomplished with logic circuitry such as comparators, counters, and memory. Calculating percent variability may require additional components and/or instructions capable of performing division, for example. Comparing the measured variability to a threshold may also require a comparator. All of these functions may be incorporated in the circuitry of an IMD, and may further be performed in real-time, e.g., to select and/or deliver an appropriate therapy based upon the arrhythmia classification. The advantages in computational simplicity described above typically result in a reduced need for memory and processing power, which may result in reduced battery capacity requirements, reduced memory storage requirements, smaller device sizes, faster responses, etc. The region-counting approach to measuring variability of a cardiac rhythm parameter may also be less sensitive to certain sensing problems like far-field R-waves (FFRWs) and undersensing. Due to the typically repetitive (regular) nature of FFRWs and 2:1 blanking, for example, these beats typically end up plotted into a fairly small number of regions in the Lorentz plot and therefore may not significantly affect the measured variability. Additionally, certain sensing problems (such as severe undersensing) may not be reflected, for example, if the Lorentz plot only plots events above (or below) a certain amount (e.g., only atrial rates greater than 100 min−1). In other words, even if certain sensing problems exist, they may not have a significant effect on the measurement of variability. Thus, embodiments of a METHOD OF AND APPARATUS FOR CLASSIFYING ARRHYTHMIAS USING SCATTER PLOT ANALYSIS are disclosed. One skilled in the art will appreciate that the invention can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation, and the invention is limited only by the claims that follow.
A method of classifying arrhythmias using scatter plot analysis to define a measure of variability of a cardiac rhythm parameter such as for example, without limitation, R-R interval, A-A interval, and the slope of a portion of a cardiac signal, is disclosed. The variability measurement is derived from a scatter plot of a cardiac rhythm parameter, employing a region counting technique that quantifies the variability of the cardiac rhythm parameter while minimizing the computational complexity. The method may be employed by an implantable medical device or system, such as an implantable pacemaker or cardioverter defibrillator, or by an external device or system, such as a programmer or computer. The variability measurement may be correlated with other device or system information to differentiate between atrial flutter and atrial fibrillation, for example. The variability information may also be used by the device or system to select an appropriate therapy for a patient.
Summarize the patent document, focusing on the invention's functionality and advantages.
[ "RELATED APPLICATION This application is a divisional of U.S. patent application Ser.", "No. 11/263,184, filed Oct. 31, 2005 entitled “Method of and Apparatus for Classifying Arrhythmias Using Scatter Plot Analysis”, now U.S. Pat. No. 7,657,307, herein incorporated by reference in its entirety.", "FIELD OF THE INVENTION Most of the embodiments of the disclosure relate generally to a method of classifying arrhythmias in implantable medical devices, and more particularly, to a method and apparatus for discriminating atrial fibrillation from atrial flutter using a measure of variability of a cardiac rhythm parameter.", "BACKGROUND A variety of techniques have been developed for collecting and interpreting data concerning the electrical activity of the heart.", "Some techniques use external medical devices (EMDs) in the clinical setting, and others use implantable medical devices (IMDs).", "Implantable cardiac monitors, such as the MEDTRONIC® Reveal™ insertable loop recorder, have also been developed and clinically implanted that employ the capability of recording cardiac electrogram (EGM) data for subsequent interrogation and uplink telemetry transmission to an external programmer for analysis by a medical care provider.", "The recorded data may be retrieved using an external programmer operated by a medical care provider.", "The programmer may include the ability to display the retrieved EGM data and/or perform processing and analysis functions on the retrieved EGM data.", "Stored segments of data can be transmitted via telemetry transmission to an external device for further analysis when a telemetry session is initiated.", "Aspects of the Reveal™ insertable loop recorder are disclosed in commonly assigned PCT publication WO98/02209 and in U.S. Pat. No. 6,230,059, the disclosures of which are hereby incorporated by reference in their entirety.", "Scatter-plots, sometimes referred to as Lorentz or Poincaré plots, have been used to plot EGM and electrocardiograph (ECG) data.", "For example, U.S. Pat. No. 5,622,178 issued to Gilham describes a system and method for dynamically displaying cardiac interval data using scatter-plots.", "Consecutive R-R intervals form a coordinate pair (e.g., the “x”", "and “y”", "coordinates) of a point that is plotted on the scatter-plot.", "Subsequent points are plotted by “sliding”", "one heartbeat to the next group of successive heartbeats (i.e., the second, third, and fourth heartbeats) and plotting the next pair of R-R intervals.", "FIG. 1 illustrates an example of this technique in plotting R-R interval data on a scatter plot.", "Such scatter-plots may provide a visual indication of the variability of the parameter plotted.", "Published Patent Application No. 2002/0065473 compares a number of consecutive R-R interval differences with a predetermined value to measure ventricular rate stability as part of a method to detect atrial fibrillation.", "A counter is incremented every time the measured R-R interval difference exceeds a threshold value, and classifies a rhythm as AF when a threshold total number is reached.", "Published Patent Application No. 2004/0092836 discloses an AF detection algorithm that uses a Cluster Signature Metric (CSM) that is based on the two-dimensional distribution of “first order lag”", "of R-R interval differences.", "Each of the above references is incorporated by reference herein in its entirety.", "In atrial fibrillation (AF), the atria depolarize at an elevated rate that is highly irregular.", "The irregular nature of the ventricular response during AF is characterized by fluctuations in the intervals between ventricular contractions.", "In atrial flutter (AFL), the atria beat at an elevated rate that is highly regular, and a certain portion of the atrial depolarizations may be conducted to the ventricles in a predictable pattern.", "There are many instances where it is desirable to be able to diagnose intermittent spontaneous cardiac arrhythmias, particularly AF and AFL, in ambulatory patients.", "Atrial rate may serve as a criterion for distinguishing between AFL and AF.", "For example, AFL (types I and II) may typically occur at rates that can range from about 220 to about 450 bpm, and AF typically occurs at rates greater than about 300 bpm.", "However, since a significant range of overlap exists between AF and AFL, and since the range of overlap may be even greater in patients taking anti-arrhythmic drugs and/or in elderly patients, a method of distinguishing them that does not rely solely on rate is needed.", "A method and system for performing scatter-plot analysis to classify cardiac rhythms is desired which minimizes computational resource requirements and allows for real-time processing of cardiac signals.", "A method of using such real-time data to affect therapy selection decisions (e.g., by an IMD) is also desirable.", "SUMMARY OF THE INVENTION In certain embodiments of the invention, a method of classifying arrhythmias includes the steps of acquiring a cardiac signal;", "deriving a recurring cardiac rhythm parameter from the cardiac signal and storing the information derived as a series of values;", "plotting a point on a scatter plot for each pair of successive stored values, the abscissa of each plotted point being equal to a first value of a pair of successive stored values, and the ordinate of each plotted point being equal to a second value of the pair of successive stored values, the scatter plot being divided into a plurality of regions;", "deriving a measure of variability by counting the number of regions in which one or more points are plotted;", "and comparing the measure of variability to a threshold value to classify the rhythm.", "In certain other embodiments of the invention, a system for classifying arrhythmias includes a sensor for acquiring a cardiac signal;", "a processor for deriving a recurring cardiac rhythm parameter from the cardiac signal and storing it as a series of values;", "a database for plotting a point on a scatter plot for each pair of successive stored values, the abscissa of the point being the first of a pair of successive stored values, and the ordinate of the point being the second of the pair of successive stored values, and wherein the scatter plot is divided into a plurality of regions;", "a processor for deriving a measure of variability by counting the number of regions in which one or more points are plotted;", "and a comparator for comparing the measure of variability to a threshold to classify the rhythm.", "In another embodiment of the invention, an implantable medical device for classifying arrhythmias includes sensing means for acquiring a cardiac signal;", "processing means for deriving a recurring cardiac rhythm parameter from the cardiac signal and storing it as a series of values;", "plotting means for plotting a point on a scatter plot for each pair of successive stored values, the abscissa of the point being the first of a pair of successive stored values, and the ordinate of the point being the second of the pair of successive stored values, and wherein the scatter plot is divided into a plurality of regions;", "a processor for deriving a measure of variability by counting the number of regions in which one or more points are plotted;", "and a comparator for comparing the measure of variability to a threshold to classify the rhythm.", "DESCRIPTION OF THE DRAWINGS FIG. 1 is an example of a scatter plot of R-R interval data.", "FIGS. 2 ( a )-( c ) illustrate a cardiac signal and various cardiac rhythm parameters derived therefrom.", "FIGS. 3 ( a ) and ( b ) illustrate a cardiac signal and a scatter plot derived therefrom in accordance with an embodiment of the invention.", "FIGS. 4 ( a )-( c ) are examples of alternate embodiments of a scatter plot in accordance with embodiments of the invention.", "FIG. 5 is a scatter plot of a cardiac rhythm parameter, the plot having a plurality of regions formed by a linear grid pattern in accordance with an embodiment of the invention.", "FIG. 6 is a scatter plot of the data shown in FIG. 5 , the plot having a plurality of regions formed by a logarithmic grid pattern in accordance with an embodiment of the invention.", "FIG. 7 is a flowchart showing the steps in a process of calculating a measure of variability from a scatter plot in accordance with an embodiment of the invention.", "FIG. 8 is a plot of a measure of variability as a function of time in accordance with an embodiment of the invention.", "DETAILED DESCRIPTION The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically.", "The drawings depict selected embodiments and are not intended to limit the scope of the invention.", "It will be understood that embodiments shown in the drawings and described below are merely for illustrative purposes, and are not intended to limit the scope of the invention as defined in the claims.", "FIGS. 2( a )-( c ) show examples of various cardiac rhythm parameters derived from a cardiac signal 20 .", "Cardiac signal 20 may be acquired from an ECG recording or from an EGM signal, for example.", "Acquiring a cardiac signal from an ECG recording may, for example, include recording electrical signals from sensors (surface leads) placed on the skin of a patient as is known in the art.", "Acquiring a cardiac signal from an EGM signal typically includes recording electrical signals from one or more sensors (leads) implanted in a patient either within or in relative close proximity to a chamber of a heart.", "EGM signals may be far-field, showing timing and morphological information associated with the entire heart, similar to that shown by an ECG, or they may be near-field, showing timing and amplitude information of a single area or chamber of the heart.", "One cardiac rhythm parameter often used to analyze heart rhythms is the R-R interval 2 , as shown in FIG. 2( a ).", "Also shown in FIG. 2( a ) is an R-R interval 3 between a “normal”", "R-wave and a PVC 5 .", "The R-R interval is an example of a recurring cardiac rhythm parameter, since it can be derived or measured on a repeating basis.", "Other recurring cardiac rhythm parameters that may be useful for analysis include, but are not limited to, the following examples: P-P interval 4 , R-wave amplitude 7 , P-wave amplitude 8 , Q-T interval 11 , and R-wave slope 6 , as shown in FIGS. 2( a ) and ( b ).", "FIG. 2( c ) shows one example of a recurring cardiac rhythm parameter, ΔR-R interval 9 , that may be derived from another recurring cardiac rhythm parameter (in this case, from the R-R intervals).", "Another recurring cardiac rhythm parameter that may be derived from R-R intervals is ventricular rate.", "Ventricular rate, for example, may be calculated as a function of the R-R interval 2 , using the equation: Rate vent (bpm)=60,000/(R-R Interval, msec).", "One of ordinary skill in the art would appreciate that other recurring cardiac rhythm parameters may be similarly derived from a cardiac signal 20 and used in accordance with embodiments of the invention, and would therefore fall within the scope of the claimed invention.", "FIG. 3( b ) shows an example of a scatter plot 10 derived from the cardiac signal 20 shown in FIG. 3( a ).", "A series of cardiac rhythm parameters 16 , such as R-R intervals, may be derived from the cardiac signal 20 as described above.", "The scatter plot 10 is formed by plotting points 14 thereon.", "Each point 14 is characterized by an x-coordinate (abscissa 22 ), and a y-coordinate (ordinate 24 ), as shown.", "Note that FIG. 3( a ) may only show a portion of the cardiac signal 20 corresponding to scatter plot 10 in FIG. 3( b ), since FIG. 3( a ) is a time plot of cardiac signal 20 , and since FIG. 3( b ) is a scatter plot 10 which condenses a large number of points 14 (N=100) corresponding to a large number of R-R intervals into a relatively small plot area.", "To illustrate the plotting of points 14 onto a scatter plot 10 , the series of R-R intervals shown in FIG. 2( c ) may be plotted based upon pairs of R-R intervals 31 - 37 as follows: A first point may have an abscissa of 700 msec and an ordinate of 750 msec corresponding to the first pair of R-R intervals 31 , 32 .", "A second point may have an abscissa of 750 msec and an ordinate of 720 msec corresponding to the second pair of R-R intervals 32 , 33 .", "Third and subsequent points are plotted following this same pattern.", "It should be noted that the choice of abscissa as the first value of each pair of values, and of ordinate as the second value of each pair of values, is somewhat arbitrary;", "the order could be reversed and would provide an equivalent result without departing from the scope of the invention.", "See FIG. 1 .", "The area of the scatter plot 10 is divided into a plurality of regions 12 .", "Each region 12 occupies a specified area of scatter plot 10 , as shown in FIG. 3( b ).", "Each point 14 is plotted into one region 12 of the scatter plot 10 .", "This may necessitate the creation of a rule for determining which region 12 a point 14 falls within in situations where the point 14 is plotted exactly on the boundary between two regions 12 .", "One such rule may simply be a “round up”", "rule, whereby a point 14 that falls exactly on a boundary between regions 12 is assigned to the “higher-valued”", "region, for example up and/or to the right in the scatter plot 10 shown in FIG. 3( b ).", "FIGS. 4 ( a )-( c ) are examples of alternate configurations of regions 12 having a shape that is not rectangular, and which occupy generally curved portions of the scatter plot 10 in accordance with various embodiments of the invention.", "Note that the size and shape of region 12 can also vary to suit a particular application.", "For example, the axes of scatter plot 10 need not be linear.", "FIGS. 5 and 6 , for example, show the same data plotted on scatter plots having linear and logarithmic axes, respectively.", "The determination of a measure of variability of a cardiac rhythm parameter is based on a graphical estimation using a region counting algorithm, as explained below.", "In FIG. 3( a ), the irregular heart rhythm (cardiac signal 20 ) is plotted in scatter plot 10 of FIG. 3( b ) based on a sequence of successive values of a cardiac rhythm parameter 16 derived from the cardiac signal 20 .", "A specified number of plotted points (the “window”", "of plotted points) is shown plotted using the Lorentz (or Poincaré) scatter-plot technique described above.", "The window may, for example, be a sliding window of N points, which slides one point at a time.", "With a sliding window, each additional heartbeat causes a new point to be plotted, and the oldest point to be removed, so that the total number of points plotted remains equal to the window size, N. Of course, the sliding nature of the window does not have to be updated with each additional heartbeat;", "a window of N points could be plotted at periodic intervals, for example, with or without overlap between successive windows.", "With continued reference to FIG. 3( b ), scatter plot 10 is shown divided into a plurality of regions 12 .", "The regions 12 shown in the particular embodiment of FIG. 3( b ) are comprised of rectangular boxes forming a grid pattern throughout the area of scatter plot 10 .", "As noted above, the regions 12 need not be rectangular or square in shape.", "The axes of scatter plot 10 shown FIG. 3( b ) range from 150 min −1 to 400 min −1 in a linear grid plot, reflecting a range of atrial rates (which may be derived from P-P intervals, for example).", "It should be noted that the axes of scatter plot 10 need not be linear, nor does it need to reflect rate or interval information.", "EGM slope and amplitude are examples of other cardiac rhythm parameters that may also be plotted, among other possible cardiac rhythm parameters.", "FIGS. 5 and 6 reflect the same cardiac rhythm parameter data plotted on linear and logarithmic scatter plots, respectively.", "To provide a measure of the variability of the cardiac rhythm parameter being plotted, a count is made of the number of regions 12 in which at least one point is plotted.", "Thus, the variability of the cardiac rhythm parameter may be represented as a number, equal to the number of regions counted containing one or more plotted points.", "Optionally, the variability may be expressed as a percentage, for example: Variability=[# regions with at least 1 point/ N points]×100% Eqn 1 or Variability=[# regions with at least 1 point/total # regions]×100%.", "Eqn 2 In one embodiment of the invention, the counting of regions containing one or more plotted points may be weighted by using a weighting factor.", "For example, in certain embodiments of the invention, it may be desirable to discount the effect on variability of points that fall in regions that are very close to certain specified areas of the scatter plot (areas that tend to have a high concentration of points plotted therein, for example).", "It may likewise be desirable to increase the effect on variability of points that fall in regions that tend to have a low concentration of plotted points.", "Thus, a weighting factor may be assigned to each region based upon its location within the scatter plot to thereby affect the measurement of variability.", "FIG. 8 shows a plot of variability over time, with each point plotted corresponding to a measured value of variability (percentage variability is shown in FIG. 8 ).", "As noted above, each measured value of variability is calculated based upon a window of N points.", "The window may “slide”", "one point at a time, or may be based on windows of N points that are “staggered”", "from one another by a specified number of points or by a specified amount of time, for example.", "FIG. 8 indicates a threshold 40 (dashed line) for differentiating types of arrhythmias based upon the measure of variability.", "In some embodiments of the invention, additional thresholds (such as threshold 42 ) may also be used to further refine the arrhythmia classification.", "A measured variability that is above a specified threshold, for example, may be used to identify an atrial arrhythmia as AF rather than AFL.", "In one embodiment of the invention, rate information may be used in conjunction with a comparison of the measure of variability to a threshold.", "For example, an atrial rate of 350 bpm may be classified as either AF or AFL based on rate information alone.", "A variability that is above a specified threshold may indicate or confirm the presence of AF, while a variability that is below a specified threshold may indicate or confirm the presence of AFL according to certain embodiments of the invention.", "In FIG. 3( b ), 100 points are plotted in scatter plot 10 based upon a series of P-P intervals converted into atrial rate information in this example.", "Scatter plot 10 is divided into a plurality of regions 12 .", "In this particular example, the regions 12 are formed by grid lines arranged on scatter plot 10 such that the spacing between grid lines corresponds to a change in atrial rate of 16 beats per minute (min −1 ).", "Each region 12 therefore occupies a space of 16×16 min −1 .", "The number of regions 12 containing one or more plotted points 14 is then counted to obtain a measure of variability.", "In FIG. 3( b ), for example, a total of 33 regions 12 have one or more points 14 plotted therein.", "In percentage terms, the resulting measure of variability may be stated as 33%, since the total number of plotted points 14 is 100.", "The process followed in calculating the measure of variability is generally summarized in FIG. 7 , which defines the following steps: Choose a cardiac rhythm parameter (e.g., P-P interval).", "Select region size/shape and window size, N. Acquire and store cardiac rhythm parameter in a database.", "Plot cardiac rhythm parameter in a scatter plot until N points are plotted.", "Calculate measure of variability by counting the number of regions containing one or more plotted points.", "(Optional) Calculate percent variability.", "Compare variability to a threshold to classify the rhythm.", "(Optional) Repeat variability calculation over time.", "The variability of the cardiac rhythm parameter is determined by “drawing”", "a Lorentz plot of a number of preceding heart beats (window size) onto a scatter plot having a certain region or grid size and shape (resolution).", "Varying the window size and/or region size/shape may have an influence on the calculated variability.", "In FIG. 3( b ), a total of one hundred points 14 were plotted, corresponding to a window size (or width) of 100 (N=100).", "The choice of N may reflect a trade-off between the desire for calculational simplicity (or speed), and the desire for accuracy or stability.", "For example, a smaller window N may provide a result sooner (i.e., not as many beats are required, and less memory storage may be needed).", "A smaller window N may also reflect changes in the measured variability sooner, since the window will not be as heavily weighted with “old”", "plotted points 14 .", "A smaller window N may also tend to reflect information that is more local or transient in nature.", "A larger window N, by contrast, while possibly requiring larger memory storage and computational resources, may tend to produce a measured variability that is more “stable,” since it is “averaging”", "a larger quantity of data into a numerical result.", "A larger window may also tend to reflect information that is more global in nature.", "The “grid”", "(or region) resolution in the example of FIG. 3( b ) was based upon a linear, square-shaped region having 16×16 min −1 dimensions.", "The resolution may be affected by the choice of size and shape of the regions used.", "For example, a choice of larger regions may result in a smaller number of regions containing one or more plotted points, thereby resulting in a lower measure of variability, according to Eqn.", "(Note: The variability measured by Eqn.", "2 may be smaller, larger, or may be unaffected by changing the size of the regions.) Conversely, selecting smaller regions may result in more regions being counted, thereby producing a higher measure of variability, according to Eqn.", "The selections of window size N and region size and/or shape may be affected by a variety of factors, such as the particular cardiac rhythm parameter being analyzed, patient history, known sensing issues (FFRWs, undersensing), etc.", "The selections regarding window size and region size/shape may also be affected by the rate/interval of the particular cardiac rhythm parameter or of the overall heart rate of the patient.", "In one embodiment of the invention, a calculation of rate/interval is made in conjunction with the variability measurement.", "The rate/interval may be an average rate based upon a certain number of beats, R;", "the number of beats R used to calculate rate may also be a parameter that can be selected and varied in accordance with certain embodiments of the invention.", "It should be noted that physically “drawing”", "or “plotting”", "the scatter plot 10 is not a required step.", "For example, the process of plotting points in a scatter plot may be performed by a memory device and logic circuitry and/or software instructions that are capable of identifying and recording which region 12 a point would fall into, and incrementing (and decrementing) counters to keep track of the points 14 that fall within each of the regions 12 .", "(Decrementing of a counter would occur, for example, when the sliding window of N points causes the oldest point 14 to be removed from the window, and hence, from the affected region 12 .) Each region 12 may, in such an embodiment, comprise a data bin for storing the number of points 14 that fall within a region, based on logic circuitry and counters, for example.", "Additional logic circuitry and/or a counter may determine the measure of variability by counting the total number of data bins that has one or more points stored therein.", "The methods of classifying arrhythmias disclosed herein are relatively simple to implement, and may be performed by an Implantable Medical Device (IMD).", "For example, the steps of plotting points and counting regions can be accomplished with logic circuitry such as comparators, counters, and memory.", "Calculating percent variability may require additional components and/or instructions capable of performing division, for example.", "Comparing the measured variability to a threshold may also require a comparator.", "All of these functions may be incorporated in the circuitry of an IMD, and may further be performed in real-time, e.g., to select and/or deliver an appropriate therapy based upon the arrhythmia classification.", "The advantages in computational simplicity described above typically result in a reduced need for memory and processing power, which may result in reduced battery capacity requirements, reduced memory storage requirements, smaller device sizes, faster responses, etc.", "The region-counting approach to measuring variability of a cardiac rhythm parameter may also be less sensitive to certain sensing problems like far-field R-waves (FFRWs) and undersensing.", "Due to the typically repetitive (regular) nature of FFRWs and 2:1 blanking, for example, these beats typically end up plotted into a fairly small number of regions in the Lorentz plot and therefore may not significantly affect the measured variability.", "Additionally, certain sensing problems (such as severe undersensing) may not be reflected, for example, if the Lorentz plot only plots events above (or below) a certain amount (e.g., only atrial rates greater than 100 min−1).", "In other words, even if certain sensing problems exist, they may not have a significant effect on the measurement of variability.", "Thus, embodiments of a METHOD OF AND APPARATUS FOR CLASSIFYING ARRHYTHMIAS USING SCATTER PLOT ANALYSIS are disclosed.", "One skilled in the art will appreciate that the invention can be practiced with embodiments other than those disclosed.", "The disclosed embodiments are presented for purposes of illustration and not limitation, and the invention is limited only by the claims that follow." ]
[0001] This is a Divisional Application of application Ser. No. 13/577,798 filed Aug. 8, 2012 which is a National Phase of PCT/JP2011/000776 filed on Feb. 10, 2011. The disclosure of the prior application is hereby incorporated by reference herein in its entirety. TECHNICAL FIELD [0002] The present invention relates to an authentication system, and to a method for registering authentication information and for matching authentication information, i.e., an authentication system that extracts, from image data, characteristics inherent to a subject image, and employs the extracted characteristics, and a method for registering authentication information and for matching authentication information. BACKGROUND ART [0003] Various types of authentication techniques for determining whether or not a subject is an authorized target have been employed for all aspects of human behavior and activities, and since the advent of the Internet and the development of the electronic processing of information, a higher level authentication technique is required. As an orthodox authentication technique, an item having a unique shape, such as a seal or a signature, is provided as a marker for a subject, and at the present, technical features, such as a hologram, an embedded pattern (a watermark), a latent image, pearl ink, microprinting, luminescent ink and intaglio printing, are employed to prevent counterfeiting. Moreover, in accordance with the development of electronic processing, predetermined information, such as a passwords, is encrypted as secret information and employed for comparison to prevent forgeries. Furthermore, various biometric authentication techniques are also employed whereby biometric data unique to an individual human body, such as fingerprints, are registered in advance, so that in a case wherein authentication is required, actual biometric data are gathered by reading and authentication performed by determining whether the biometric data gathered for the case matches the registered biometric data (see, for example, patent literature 1). CITATION LIST Patent Literature [0000] PTL 1: Japanese Patent Laid-Open No. 2009-205393 SUMMARY OF INVENTION [0005] However, of the above described authentication techniques, a problem exists, with the technique for which a password is employed, in that since a password must be decided in advance and a user must remember the password, the amount of information involved is so extremely small that stealing or forgery of the information could be easy. [0006] For the technique that employs biometric data, only a human being can be employed for a determination as to whether or not a subject is an authorized subject, and basically, targets or other animals or plants can not be used. However, as another problem, recently, since an action for forging biometric data has occurred, the authentication technique for which biometric data is employed is not always completely safe. [0007] Furthermore, since most high-level authentication techniques require the advance physical or electronic attachment of authentication information to a subject, processing performed for the subject is required, so that promotion of the use of the authentication technique is hindered. [0008] While taking the above described conventional problems into account, one targetive of the present invention is to provide an authentication system that does not require processing for a target to be authenticated and that extracts unique data from image data representing individual characteristics of the target, which are obtained under predetermined configuration requirements, by employing a standard digital imaging apparatus having a predetermined configuration and then employing the extracted unique data to determine whether the target is an authorized target, as well as a method for registering authentication information and for matching authentication information. [0009] To achieve this targetive, the invention according to claim 1 is characterized by comprising: [0010] storage means for storing, as individual difference data used to uniquely identify a target to be authenticated, connected lines that are generated in such a manner that a plurality of sets of digital data are obtained by scanning and resolving the target using digital imaging means, an optical data difference is calculated at corresponding positions, designated by the digital data, midpoints for physical positions of a subject, which correspond to center positions of pixels located at the obtained corresponding positions, are calculated based on a physical size of the subject that corresponds to a pixel size of the digital imaging means, and are coupled in order, as connection points, beginning with the largest optical data difference; [0011] transformation value calculation means for, when the digital imaging means has obtained digital data through scanning, multiple times, the target to be authenticated under configuration requirements for the digital imaging means, comparing a plurality of sets of the thus obtained digital data, and calculating translation and rotational transformation of the individual digital data sets in order to match positions for mapping the target to be authenticated; and [0012] individual difference data extraction and determination means for employing the obtained translation and rotational transformation to identify correlated positions of pixel arrays of the plurality of digital data sets and to read, from the storage means, the connected lines for the individual difference data for the corresponding positions, for tracing a polygonal line to search for locations of the connection points present on the connected lines that have been read, and for calculating an optical data difference of pixels on physical pixel planes that include the locations of the connection points, and that are superimposed, and when it is determined that a predetermined relationship is established between the obtained optical data difference and the order of the connected lines, determining that authentication is successful. [0013] For the invention according to claim 2 , the authentication system of claim 1 is characterized in that: [0014] a resolution of the digital imaging means is included in configuration requirements for the digital imaging means; and [0015] the resolution of the digital imaging means is lower than a particle size used to form an image of the target to be authenticated. [0016] For the invention according to claim 3 , the authentication system of claim 1 or 2 is characterized in that the transformation value calculation means sequentially scans the target to be authenticated a plurality of times. [0017] For the invention according to claim 4 , the authentication system of one of claims 1 to 3 is characterized by further comprising: [0018] correction means for employing predesignated information to perform correction for normalizing a difference in image data caused by a difference in configuration requirements for the digital imaging means. [0019] The invention according to claim 5 , the authentication system of one of claims 1 to 4 is characterized in that: [0020] the storage means also stores a line connection comparison setup, including parameters and comparison methods, to be used for comparison of connected lines; and [0021] the individual difference data extraction and determination means employs the comparison setup stored in the storage means to trace, along a polygonal line, positions of connection points on the connected lines that have been read, and determines that authentication is successful, when the obtained optical data difference indicates, with respect to the order of connection lines, a predetermined relationship that is designated in the comparison setup. [0022] For the invention according to claim 6 , the authentication system of one of claims 1 to 5 is characterized in that when the obtained optical data difference indicates a descending order by a predetermined number, with respect to the order of the connection lines, the individual difference data extraction and determination means determines that authentication is successful. [0023] The invention according to claim 7 is an authentication information registration method, characterized by comprising: [0024] a transformation value calculation step of calculating parallel translation and rotational transformation, so that based on predetermined configuration requirements for digital imaging means, a target to be authenticated is scanned by the digital imaging means a plurality of times to obtain digital data, a plurality of sets of digital data thus obtained are compared with each other, and locations at which mapping for the target to be authenticated is performed using the digital data are matched; [0025] a step of employing the obtained parallel translation and rotational transformation to designate correlated locations of pixel arrays of the plurality of sets of digital data, and calculating an optical data difference for the correlated locations that are designated; [0026] a step of calculating a physical size for a subject, with respect to a pixel size of digital data based on configuration requirements for the digital imaging means, employing the obtained physical size to calculate, as connection points, midpoints of physical positions of the subject that correspond to the center positions of pixels that are located at the corresponding positions, coupling the connection points in the descending order, by an arbitrary number of times, beginning with the largest optical data difference, and extracting connected lines as individual difference data; and [0027] a registration step of registering the extracted connected lines at storage means. [0028] For an authentication system that includes storage means for storing, as individual difference data used to uniquely identify a target to be authenticated, connected lines that are generated in such a manner that a plurality of sets of digital data are obtained by scanning and resolving the target using digital imaging means, an optical data difference is calculated at corresponding positions, designated by the digital data, midpoints for physical positions of a subject, which correspond to center positions of pixels located at the obtained corresponding positions, are calculated based on a physical size of the subject that corresponds to a pixel size of the digital imaging means, and are coupled in order, as connection points, beginning with the largest optical data difference, the invention according to claim 8 is characterized by comprising: [0029] a transformation value calculation step of, when the digital imaging means has obtained digital data through scanning, multiple times, the target to be authenticated under configuration requirements for the digital imaging means, comparing a plurality of sets of the thus obtained digital data, and calculating translation and rotational transformation of the individual digital data sets in order to match positions for mapping the target to be authenticated; and [0030] an individual difference data extraction and determination step of employing the obtained translation and rotational transformation to identify correlated positions of pixel arrays of the plurality of digital data sets and to read, from the storage means, the connected lines for the individual difference data for the corresponding positions, tracing a polygonal line to search for locations of the connection points present on the connected lines that have been read, and for calculating an optical data difference of pixels on physical pixel planes that include the locations of the connection points, and that are superimposed, and when it is determined that a predetermined relationship is established between the obtained optical data difference and the order of the connected lines, determining that authentication is successful. BRIEF DESCRIPTION OF DRAWINGS [0031] FIG. 1 is a system configuration diagram for an authentication system according to one embodiment of the present invention; [0032] FIG. 2 is a functional block diagram for the embodiment of the present invention; [0033] FIG. 3 is a flowchart showing an authentication process performed for the embodiment of the present invention; [0034] FIG. 4 is a diagram for explaining the principle of the present invention; [0035] FIG. 5 is a diagram for explaining the processing, of the embodiment of the present invention, for extracting an individual identification pattern; [0036] FIG. 6 is a diagram for explaining the processing, of the embodiment of the present invention, for extracting an individual identification pattern; [0037] FIG. 7 is a diagram for explaining the processing, of the embodiment of the present invention, for extracting an individual identification pattern; [0038] FIG. 8 is a diagram for explaining the authentication processing performed, for the embodiment of the present invention, by employing an individual identification pattern that has been extracted in advance; [0039] FIG. 9 is a diagram for explaining an example, for the embodiment of the present invention, wherein a determination for matching is performed through the authentication processing performed by employing an individual identification pattern that has been extracted in advance; [0040] FIG. 10 is a diagram for explaining an example process, of the embodiment of the present invention, for correcting a target image that is extracted; [0041] FIG. 11 is a diagram for explaining the process for correcting a specific example for which the embodiment of the present invention is applied; [0042] FIG. 12 is a diagram for explaining a matching process performed for specific examples for which the embodiment of the present invention is applied; [0043] FIG. 13 is a diagram for explaining another specific example for which the embodiment of the present invention is applied; [0044] FIG. 14 is a diagram for explaining an additional specific example for which the embodiment of the present invention is applied; [0045] FIG. 15 is a diagram for explaining a further specific example for which the embodiment of the present invention is applied; [0046] FIG. 16 is a diagram for explaining yet one more specific example for which the embodiment of the present invention is applied; [0047] FIG. 17 is a diagram showing an example tinted-glasses connection for the embodiment of the present invention; [0048] FIG. 18 is a diagram showing an example connection method for a one-stroke line image according to the embodiment of the present invention; [0049] FIG. 19 is a diagram showing another example connection method for a one-stroke line image according to the embodiment of the present invention; [0050] FIG. 20 is a flowchart showing the processing for registering individual difference data according to this embodiment; [0051] FIG. 21 is a flowchart showing the authentication processing performed for this embodiment; [0052] FIG. 22 is a detailed diagram for explaining calculation of an optical data difference according to this embodiment; and [0053] FIG. 23 is a diagram for explaining an example, for the embodiment of the present invention, wherein determination for matching is performed through authentication processing employing an individual identification pattern that has been extracted in advance. DESCRIPTION OF EMBODIMENTS [0054] One embodiment for an authentication system, a method for registering authentication information, and for matching authentication information of the present invention will now be described, while referring to drawings. <Principle Of Individual Authentication System> [0055] The system of this embodiment determines the identity of a target to be authenticated, based on principles related to unique information for the target extracted from image data, which represents the characteristics of each target obtained, under predetermined configuration requirements by a standard digital imaging apparatus having a predetermined configuration, without any processing being required for the target, and based on a unique information extraction method, for extracting unique information from an image that was read, and an individual authentication method, for authenticating a target, as needed, based on the unique information that is extracted. Further, targets can include arbitrary materials, such as printed matter and various finished products or parts, and human bodies, so long as an image can be obtained by scanning or imaging the surface. <Unique Information Based on Individual Difference> [0056] The purpose for scanning a material that actually exists using a digital imaging apparatus, such as a scanner or a camera, is to quantize the status of the surface; however, the entire structure of the material to be processed can not be read. It can be said that scanning of the surface of the material is mapping of a phenomenon that occurs, moment by moment, on the surface of the material. For example, when image scanning is performed by an image sensor (CCD/CMOS) wherein light-receiving portions, such as imaging elements, which react to light of an optical wavelength (a visible light range of a short wavelength of 360 nm to 400 nm to a long wavelength of 760 nm to 830 nm) are arranged on the plane, a difference occurs in the image processing, the primary color spectroscopy and the element configuration, but reproduction for digital mapping of phenomenon is performed by a color imaging process (numerical imaging process) during which collected light is separated into RGB and others, charge reactions of the individual light-receiving portions are quantized to numerical values, and the numerical values are arranged in order and output as array data. The optical mapping data obtained is a numerical value replaced with the scale of a resolution that corresponds to the XYZ arrangement. Further, for the image sensor, when a pixel resolution is high, i.e., when the sizes of the individual light-receiving portions of the sensor are smaller than the wavelength of light, optical observation is disabled, or when the light-receiving portions are greater, observation of the material by the individual light-receiving portions is also disabled. Furthermore, since a natural substance is arranged at random, reconstruction of the natural substance is also impossible by using the image sensor, where the light-receiving portions are provided as arrays. [0057] This indicates resolving power, and image data is formed in such a manner that, when reactions have occurred relative to light received in consonance with the sizes of elements, which are scan unit areas for the image sensor, the reactions are quantized to be provided as an array, i.e., when the amount of electricity is generated in consonance with light received at the individual elements arranged in a predetermined form in the image sensor, the amount of electricity is provided as an array. Therefore, this quantization process is also eventually a color compression process for performing quantization for a phenomenon that occurs in one part of a target that corresponds to one scan unit area, and it can be said that image data obtained by arranging the results is a phenomenon resolved in accordance with the size of the scan unit area. That is, image data obtained by scanning is changed in accordance with configuration requirements, such as a resolution, and in this embodiment, this phenomenon is focused on to extract unique information for a target. Here, the configuration requirements are the structural and exposure requirements for an imaging apparatus, consisting of parameters that represent the physical locations, the types, the sizes, the resolutions, the lens arrangements and the lens magnifications of imaging elements, and the physical location, the luminescence, the frequency properties, the color temperature of a lighting device, such as an LED, a subject distance relative to a target to be authenticated, a focal position, a focal length, a shutter speed, a frame rate, and a positional relationship between the target to be authenticated and an optical system that includes the lenses and the imaging elements. [0058] Since a target for which authentication is actually to be determined is formed of a natural material, the smallest size of this material is a “particle”, which is even smaller than nano- and micro-sized. Photons are larger than these particles, and for visible light, since the wavelength is set in the visible light range between a short wavelength of 360 nm to 400 nm to a long wavelength of 760 nm to 830 nm, light (visible light) is not reflected at the unit area of a substance that is smaller than the above described size. Therefore, the phenomenon of a natural substance that is much smaller than the scale of a resolution can not be interpreted by quantization using a sensor; however, the reading results, i.e., the values output by the sensor are affected by the phenomenon that occurs in the unit area of that size. That is, when the scanning position is shifted even slightly (by micro-order), i.e., when the positions of the arrays of image data obtained by reading the same target a plurality of times are slightly shifted away from the corresponding locations of the elements of the image sensor employed for reading, the corresponding numerical values of optical data to be obtained by the elements are adversely affected, and thus, even when scanning of the same target is repeated under the same condition, the same scan data can not be obtained. This phenomenon always occurs so long as an image sensor that has a resolution smaller than the wavelength of light is not provided, and in this invention, a difference in the reading results is called a resolution difference. FIG. 4 is a diagram for explaining this difference resolution by employing a specific CCD sensor. It should be noted that an example shown in FIG. 4 is merely an example for which this principle is applied, and the present invention is not limited to any of the techniques specifically described in this example. [0059] Referring to FIG. 4 , generally, in a CCD sensor, for example, that is employed for a scanner that reads a target to be authenticated, light is split into RGB light, etc., by imaging elements arranged at predetermined intervals, as illustrated, and the visible light having a wavelength (in a visible light range of a short wavelength of 360 nm to 400 nm to a long wavelength of 760 nm to 830 nm) enters the apertures of the imaging elements and are converted into electrical charges, which are then accumulated. The RGB visible light is digitized by employing the accumulated electrical charges as the intensity of light, and based on the numerical digital values for RGB, etc., color compression is performed for incident light that is limited by the pitches and the apertures of the imaging elements, so that one color is allocated for one element, and the target to be authenticated is expressed as a color data array. The thus obtained color data array is expressed as numerical data that represent the coordinates for the locations of the imaging elements and the individual components, such as RGB, of the trichromatic system. For example, assuming that the color data array is (X coordinate, Y coordinate: R, G, B), data like (1, 1: 112, 28, 93), (1,2: 17, 30, 104), (1, 3: 39, 36, 107), . . . , are obtained, as illustrated, and these values differ from each other because each time the scanner reads the target, the scanning position is varied by micro order. [0060] The resolution difference also occurs for printed matter produced in a nano-size or micro-size. When images are obtained by scanning duplicate copies (mass-produced goods) like printed matter, there is an influence, exerted by a printing error and a difference in paper surfaces, at a nano-level or a micro-level, which can not be really observed for the actual phenomenon. That is, the characteristics of an individual based on nano-sized particles, which are provided without the intention, or which are not available for mass production even with the intention, are incorporated into the resolution difference. A difference that is generated, due to a difference between resolutions during scanning of the target, and due to the characteristics of an individual, is called an “individual difference” in this invention. <Extraction of Information Unique to Target> [0061] According to this invention, a difference in individuals is obtained from targets, such as printed material, although not limited to them and unique information for one target is extracted, based on the obtained individual difference, and is employed for the authentication processing. One such method for extracting information inherent to a target will now be explained. As described above, when image data are output each time scanning is employed, reproduction of the resolved images becomes unstable, and a difference in individuals is incorporated into the image data. However, since the values obtained simply by resolving are generally not constant, these values can not be employed as information that uniquely represents the target. Therefore, information for obtaining a predetermined relation is extracted from the individual difference. That is, the data obtained by scanning are compared, based on the corresponding positions for these data, and are rearranged in order, beginning with the data where the greatest change is made, and the positional relationship of the data is replaced by the three-dimensional coordinates, the points of which are connected in order, so that a specific polygonal line pattern, i.e., a “line” is generated, along which “reconstruction instability element points”, which are elements used to prevent the same image resolving due to an individual difference, are arranged in the order of strength of reconstruction instability. As previously described, regardless of the resolution of the sensor of the scanner, this “line” can always be generated by scanning the image of a target, and the order for drawing the “line” includes predetermined universality based on the uniqueness of the information that is inherent to the target. [0062] Since the order for drawing the line is the order in which reproduction instability occurs, specifically, this order can be obtained in such a manner that the same target is scanned at least twice, and the ranking that represents differences in the scanning results is specified. According to the fundamental principle of the present invention, while there is a problem that, each time a target is scanned, the same results are not always obtained, depending on physical conditions (the wavelength and property of light), and for mass-produced goods, such as printed material, only an identification of the type is enabled by a comparison of the obtained individual difference and identification of an individual is difficult, this problem can be resolved by using a more specific method, whereby, instead of performing a comparison of individual differences, the ranking for instability for image reproduction is observed for each array that is scanned, in order to enable identification of an individual. This can be realized based on the fact that a target physically exists and the fact that the arrays of the image sensor are physically present. That is, the arrangement of the image sensor is physically constant, and since the probability that the internal structure of the image sensor will be adversely affected when a scanning position is shifted for each scanning is at least lower than the probability that shifting will occur in the scanning position, it can be assumed that the arrays of the image sensor be maintained in the original configuration state. Therefore, in the “line” pattern obtained from image data (array values) in the scanned area, the positional relationship is maintained. That is, for the individual elements of the image sensor, the values are changed for each scanning, but the order of differences is maintained. Further, when different printed matter, for example, is employed as a target and is scanned along the above described “line” pattern, a probability of matching is low, and a probability, which will be described later, is obtained based on the number of “reproduction instability element points”, so that determination of authentication can be appropriately performed. Since the “line pattern” represents image resolving instability, i.e., expresses the degree of instability as to the values that are obtained for image data by the corresponding elements, the line pattern also indicates the order at which reproduction instability occurs. In this case, since it is simply required that the “line pattern” express the degree of instability for reproduction, the line pattern can be obtained by scanning the same target sequentially at least twice, and employing the ranking for differences of the scanning results. That is, image data obtained by sequentially scanning twice, for example, differ slightly from each other, because of the characteristics of the target that are smaller (finer) than the resolution level employed for scanning, and when these differences are processed based on the concept, such as the ranking, the detailed characteristics of the target can be obtained. In this case, scanning is generally sequentially repeated twice, i.e., performed within a predetermined period of time, because when a time interval is too long, a phenomenon that has occurred in the target is greatly changed, and the above described principle might not become effective. For example, in a case wherein the power of the imaging apparatus is turned off after the first photographing was performed, the imaging conditions are greatly changed due to non-reversibility for the amount of electric charges in the image sensor and the sensitivity to the amount of light, and there is a probability that adjustment for the conditions will be difficult. Therefore, it is preferable that photographing multiple times be performed within a predetermined contiguous period, or be continuously performed in the state wherein almost the same photographing conditions are maintained. According to the principle of the present invention described above, no new apparatus is required, while a phenomenon that can not be captured in a single image resolving process is estimated by employing a plurality of sets of image data, and a phenomenon of a target beyond the resolving power of the image sensor can be obtained. [0063] One process for extracting information inherent to a target will now be described by employing the above described principle. Referring to FIG. 5 , as explained while referring to FIG. 4 , a camera 501 where a CCD or CMOS image sensor is mounted sequentially scans a target 502 multiple times under the same configuration requirements, and obtains digital data. FIG. 20 is a flowchart showing the processing for registering individual difference data according to this embodiment. [0064] Since a different imaging apparatus might also be employed for authentication, standard instruction data are employed to obtain, in advance, correction values for normalizing the image resolving process, i.e., for performing a sight defect correction, such as a correction of the location of an imaging apparatus, etc., employed to calculate individual difference data, corrections of a resolution and the light-receiving color temperature for a sensor, white balance correction, ISO speed correction, lens distortion correction, correction of chromatic aberration, concentration correction, correction of the amount of light for illumination, spectrum correction and conversion that is consonant with the type of an imaging apparatus. A filter provided for using these correction values is employed for the obtained image data. With this arrangement, the individual pixel values of image data can be changed, and regardless of the configuration of the imaging apparatus, the reading of image data is enabled under a predetermined condition; however, the method is not limited to this, and the exchange of data representing correction values may also be performed while the data are stored in a storage device, or another method well known for this technical field may be employed to generate image data. For example, in a case wherein different imaging apparatuses are employed for registration and for authentication, the resolution may be stored in advance, and when low-resolution image data is to be processed, the resolution of the low-resolution image data may be changed to the same level by being increased (the amount of data becomes greater as the resolution is increased, while the numerical value is unchanged), or decreased. [0065] The same images 512 and 522 are actually captured for the target by the first scan and second scan; however, when image data 511 obtained the first time and the image data 521 obtained the second time are compared, it is understood that different array data are obtained due to a slight difference in the scanning positions of a scanner. Specifically, compared with the array of the image data 511 obtained during the first scan, (1,1: 112, 28, 93) (2,1: 17, 30, 104) (3,1: 39, 36, 107) (4,1: 221, 38, 108), . . . , the array of the image data obtained by the second scan slightly differs, which is (1,1: 110, 45, 99) (2,1: 28, 24, 167)(3,1: 35, 41, 100)(4,1: 209, 43, 111), . . . . [0066] Then, a resolution difference is extracted from a plurality of image data sets obtained by scanning the target multiple times in the above described manner. Specifically, as shown in FIG. 6 , a plurality of sets, two sets in this case, i.e., image data 601 and 602 are employed to extract a differential image 603 , and a resolution difference that occurs when image resolving is performed multiple times is regarded as an optical data difference, and is employed to reveal an individual difference. In a case wherein a resolution difference is to be calculated, comparison of different points is meaningless, and transformation values for translation and rotation for the individual sets of image data are calculated to align the positions where the same portion of the subject is to be mapped. The transformation values obtained for the image data are employed to superimpose the pixel arrays of the individual sets of image data, and optical data of pixels at the aligned positions are compared to calculate an optical data difference. Any well known method for this technical field can be employed for the calculation of the transformation values for aligning the positions. [0067] For calculation of these transformation values, for example, several characteristic points may be extracted from the individual sets of image data, and affine transformation, for example, may be performed to match these characteristic points; however, the calculation method is not limited to this. In this embodiment, for a comparison of a plurality of sets of image data, points correlated with each other are designated, and transformation values are calculated, which indicate how translations, such as parallel shifts, or rotations should be performed for image data in order to superimpose the points; however, instead of actually changing image data to overlay, the transformation values are employed to specify corresponding points, and a difference of optical data is obtained for pixels located at the corresponding points. This is because there is a probability that, when image data are superimposed by actually performing transformation, a slight shift occurs. Therefore, so long as such a shift can be avoided, it may actually be possible for the transformation process to be performed for the image data, following which a difference is calculated and the above processing is performed. [0068] FIG. 22 is a diagram for explaining a detailed example for this embodiment for calculating an optical data difference. As described above, according to this embodiment, transformation is performed for image data that are obtained by scanning a target multiple times, so that the positions of image data where mapping of a subject is performed are aligned, and the optical data for the individual pixels that are correlated with each other are compared to obtain an optical data difference. Specifically, this operation can be performed through the processing shown in FIG. 22 . First, transformation values for image data A 2201 and image data B 2202 are calculated so as to align the positions for mapping a subject. Then, the image data A and B are transformed, the obtained optical data for corresponding pixels (RBG components in this example) are compared, and a difference of the optical data is employed as an optical data difference for the corresponding physical positions. More specifically, virtual image data P 2203 shown in FIG. 22 is prepared (thus, the size of the image data P is smaller than that of the image data A or B), and the individual points of the image data A and B are obtained based on the corresponding points of image data P 2203 . As shown in enlarged image data portions A 2205 and B 2206 , the pixels of the image data A and B do not completely match when the data are superimposed, and a specific pixel in the image data A 2205 overlaps a plurality of pixels in the image data B 2206 . [0069] Therefore, in this embodiment, for example, for acquisition of an optical data difference, a difference is calculated between an optical data value for one pixel and optical data values of a plurality of pixels that overlap that pixel; however, the method is not limited to this, and any other well known method in this technical field can be employed for calculation. In this case, a connection point that will be described later can be a midpoint 2211 of a center point 2209 of one pixel and a center 2210 of center points of corresponding multiple pixels. As a result of calculation, the image of the obtained optical data difference is expressed using color. It should be noted that, in actuality, the above described intermediate process is not present, and a one-stroke line pattern is directly obtained based on data for the optical data difference. When the individual component values are added together, the obtained total value is regarded as an optical data difference with respect to the image data A and B. [0070] In this manner, the resolution difference can be represented as a phase difference at the position where corresponding images are superimposed, by employing, for example, the sum of the absolute values of the differences for the individual RGB components at each image superimposition position, as shown in FIG. 6 . Here, since as described above the superimposition positions of pixels of the image data 601 and 602 should be identified in order to obtain a difference between the image data 601 and 602 , the individual characteristic points of the individual image data sets are employed to specify in advance the corresponding positions to superimpose, so that optical data for the same portion of a subject can be compared with each other. As a result of such superimposition, the individual pixel values that correspond to the physical positions of the image data A 601 and B 602 are compared for each of the RGB components, and the obtained difference is expressed using color as an optical data difference C. That is, for the image data 601 , when array A (1,1: 112, 28, 93) (2,1: 17, 30, 104) (3,1: 39, 36, 107) (4,1: 221, 38, 108) . . . and array B (1,1: 110, 45, 99)(2,1: 28, 24, 167) (3,1: 35, 41, 100)(4,1: 209, 43, 111) . . . are converted into actual distances, A′ (0.009, 5.391, 0.0: 112, 28, 93) (0.027, 5.391, 0.0: 17, 30, 104) (0.045, 5.391, 0.0: 39, 36, 107) (0.063, 5.391, 0.0: 221, 38, 108) . . . (coordinate unit of μm) and B′ (0.011, 5.392, 0.0: 110, 45, 99) (0.031, 5,392, 0.0: 28, 24, 167)(0.048, 5.392, 0.0: 35, 41, 100)(0.066, 5.392, 0.0: 209, 43, 111). A′(+)B′=CB′ (0.011, 5,392, 0.0: 110, 45, 99) (0.031, 5.392, 0.0: 28, 24, 167)(0.048, 5.392, 0.0: 35, 41, 100) (0.066, 5.392, 0.0: 209, 43, 111). [0071] The resolution difference thus obtained includes an attribute unique to a target because characteristics inherent to the target are incorporated, and a predetermined correlation exists for the results that are extracted by scanning the same target multiple times. In order to make this relationship more apparent, i.e., to enable authentication of the target, the obtained resolution difference is employed to connect the reproduction instability element points. That is, based on the resolution difference, the reproduction instability element points are arranged in the descending order of the reproduction instability strength, i.e., the midpoints of the individual superimposition positions in the above described example are arranged in order beginning with the greatest value of an optical data difference, and this order represents reproducibility with respect to the image resolving process of a target to be photographed, i.e., a predetermined correlation is established about the same target. Compared with an individual difference, the numerical value of the reproduction instability strength, i.e., the optical data difference for the individual sets of image data, is more adversely affected by an error that occurs during the image resolving process, and therefore, is not appropriate as information unique to a target. Therefore, the points are rearranged and connected in order, while the numerical value of the reproduction instability strength is disregarded and only the positional information is taken into account. For positional information, the size of imaging elements, which are constituents of an imaging apparatus, and configuration information of an optical system, such as the lens structure and a subject distance, are employed, and the physical size of a subject that corresponds to the pixel size of image data is calculated based on the positions of pixels that are superimposed, and then, the midpoint of the physical mapping positions for the center points of pixels that are superimposed is obtained, so that the positional information is employed to support a case, for example, wherein the ratio of the size of image data to the size of a subject is changed when the configuration of an imaging apparatus differs for registration and for authentication. [0072] Specifically, as shown in FIG. 7 , the transformation values of the individual image data sets, which have been superimposed to obtain the optical data difference in FIG. 6 , are employed to change the superimposed pixel positions to the physical positions (three-dimensional positions) of a subject, which is mapped at the pixel center point, and the midpoints of these physical positions are employed as positional information of the individual connection points along connected lines in a polygonal line pattern that represents an individual difference. Optical data differences 701 D (25) (80) (16) (20) . . . are rearranged in the order of the values of optical data differences, and A′ (3.353, 0.072, 0.0) (1.771, 0.960, 0.0) (5.295, 5.245, 0.0)(4.276, 0.928, 0.0) . . . and B′ (3.357, 0.072, 0.0)(1.773, 0.963, 0.0)(5.292, 5.247, 0.0) (4.275, 0.927, 0.0) . . . are obtained, which are physical positions of a subject that is mapped at the center positions of corresponding pixels for the first two image data sets that are employed for calculation of difference values. When positional information of the midpoint (the averaged position for the X, Y and Z axes) is L(3.355, 0.072, 0.0) (1.772, 0.9615, 0.0) (5.2935, 5.246, 0.0)(4.2755, 0.9275, 0.0) . . . , connected lines as shown in an image 702 are generated, which represent an individual difference obtained from the image data in the scan area. Here, connected lines or an image representing these connected lines is called a one-stroke line image. As will be described later, the obtained one-stroke line image provides the order for reproducibility, which can not be obtained by a single image resolving process, and represents characteristics unique to a target. [0073] Through the above processing, it is possible to obtain data relative to connection of reproduction instability element points, which is individual difference data extracted based on a difference between individuals included in data obtained by scanning a target, and in this embodiment, the individual difference data is employed to perform authentication of the identify of a target. However, the individual difference data and the extraction method described above are merely representative examples for the present invention, and so long as information is inherent to a target and is incorporated to a resolution difference in image data obtained by scanning a target, such information can be extracted by using an arbitrary method well known in this technical field, and can be employed as individual difference data for this invention. Furthermore, in the above described description, the RGB component values are employed; however, as is apparent from the principle of the present invention, any data can be employed so long as the data is obtained by optically scanning the state of the surface of a target at a predetermined resolution, and consists of arrays representing the intensity of light for each scan unit area. <Target Authentication Process> [0074] While referring to FIGS. 8 , 10 and 23 , an explanation will be given for a method for authenticating a target based on individual difference data obtained above, i.e., a method for employing individual difference data to determine whether a target, such as printed matter, matches a target from which individual difference data was already extracted. First, an explanation will be given for a precondition that predetermined similarity is established in a case wherein reproducibility in the order of the reproduction instability element points, i.e., the positional information of the connection points is arranged for the same target, in the order of the strength of optical data difference, beginning with the greatest value. FIG. 21 is a flowchart showing the authentication processing performed for this embodiment. [0075] As shown in FIG. 8 , image data is obtained in advance by reading a target 502 using a scanner, etc., multiple times, and individual difference data, represented by connecting lines in an image 801 , is extracted and stored in some storage means, such as a database. In this case, the target is further scanned by the camera 501 multiple times, and as shown in an image 802 , the one-stroke line pattern in the image 801 extracted in advance is employed to overlay the pixels at the connection positions of the one-stroke line pattern, and an optical data difference is obtained at the positions corresponding to the pixels, or specifically, the connection positions are compared in the order of connecting lines. As a result of comparison, since the individual difference is reflected in the resolution difference, the one-stroke line images do not completely match, as shown in FIG. 8 ; however, as for the points of a one-stroke line pattern of the image 801 and those of the image 802 , predetermined reproducibility is established for the order of reproduction instability element points and a one-stroke line pattern 803 can be obtained. Therefore, for one-stroke line patterns obtained for the same target, since reproducibility is present in the order in which the corresponding points are connected, the degree of matching for the order can be employed to determine the identify of an individual. [0076] Here, in this embodiment, matching for a target is performed by comparing the positions of the connection points that are arranged in the descending order of the strengths of differential optical data; however, a method for comparison of one-stroke line images is not limited to this method, and various pattern comparison methods, i.e., variations on the connection comparison method, are available, such as a method for coupling the points in order, beginning with the lowest level of the reproduction instability element strength, and comparing these points. In a case wherein the present invention method is employed, since a limitation of a target to be authenticated is enabled by using parameters and a comparison method that are appropriate for a target to be captured, these parameters and a comparison method are together called a tinted-glasses connection, or a connection and comparison setup. For a tinted-glasses connection, the following various parameters are employed, and a connection type for a one-stroke line image is determined in accordance with a set of the parameters. An example for the tinted-glasses connection is shown in FIG. 17 . Further, the connection types for a one-stroke line image are shown in FIGS. 18 and 19 . In FIG. 18 the index type is shown, and in FIG. 19 the sequence type is shown. The parameters employed for the tinted-glasses connection are: ((the order (forward or reverse) of reproduction instability element strengths)(the least required connection distance)(the threshold strength value)(change in strength)(the number of connection points)(the scan area size)+α)). [0077] Further, a one-stroke line image formation example that corresponds to these parameters is as follows. [0000] Index type “one-stroke line image”: ((starting point: three dimensional Cartesian coordinates XYZ) (starting point: a three dimensional vector) (a distance)+the number of points×((a three dimensional vector) (a distance)) Sequence type “one-stroke line image”: The number of points×three dimensional Cartesian coordinates XYZ [0078] That is, various comparison methods can be employed, such as one for employing the ascending order, instead of the descending order, which will be described in detail below, one for skipping reproduction instability element points, for which the distances do not reach the least required connection distance, one for skipping elements, for which the change in strength is equal to or lower than a predetermined level, one for connecting points until the number of connection points reaches the maximum value, or one for connecting points only within the range of a designated area. Furthermore, the most appropriate tinted-glasses connection can be employed in accordance with a material on which a target is presented and a method for representing the target, i.e., a printing method and an ink type used for the target, and it is also required for the actual authentication process to determine in advance which tinted-glasses connection should be employed. Therefore, in a database, etc., used to store individual difference data described above, associated information concerning tinted-glasses connections to be employed is stored in correlation with the individual difference data by using a predetermined method, so that the authentication process can be performed, based on the individual difference data, under optimal conditions. The associated information can include not only information for the tinted-glasses connection, but also other useful information employed when the identity of an individual is to be determined based on the individual difference data. [0079] Next, a method for determining the identity, i.e., a method for determining reproducibility for the order of reproduction instability element points, will be described. A specific process example shown in FIG. 23 is employed for this explanation. For match determination for a target to be authenticated, first, a one-stroke line pattern 2301 extracted and registered at first is traced along the connection order to examine whether a predetermined relationship has been established for the differential values of optical data of pixels, for which the individual connection positions correspond to the physical portions of the pixels of image data 2302 that have been obtained and superimposed for authentication. In this case, match determination is performed by using a comparison method defined based on the tinted-glasses connection. For example, in a case wherein a matched polygonal shape is formed of three points, every three connection points of the one-stroke line pattern, from the beginning, are examined to determine whether the order relation is established for the corresponding points, and when the correspondence of the three points is established, the pertinent polygon is regarded as a matched form to increment the number of polygonal shapes. Then, examination for the correspondence relation is sequentially performed until the end point of the one-stroke line image. As a result, matched forms are stored in a matched polygon array, and in a case wherein the number of matched forms is equal to or greater than a threshold value for match determination, it is determined that authentication has been successful. Of course, a search of matched polygons may also be performed until a predetermined count is reached, and when the count value goes beyond the predetermined count, it may be assumed that authentication has successful and that the processing may be terminated. [0080] In this embodiment, during the authentication process, instead of generating connected lines, the connected lines that were registered are traced for image data obtained by scanning for authentication, and the number of matched sequences are counted. However, during the authentication process, connected lines may also be generated and be compared with each other to determine the identify. A specific matching process using polygons will now be described while referring to FIG. 9 . Specifically, as a method for comparing one-stroke line images, every three points of each one-stroke line image, from the beginning, are employed to obtain a correlation of them, and when three points of two image are matched, it is assumed that a matched polygon is present, and the number of matched polygons is incremented to determine the identity. Matching using polygons is also performed by comparing a one-stroke line pattern indicated by an image 902 , which represents individual difference data that was again extracted at the time of authentication, with a one-stroke line pattern indicated by an image 901 , which represents individual difference data that was extracted and registered first. Comparison and match determination for the two one-stroke line patterns are performed in accordance with one tinted-glasses connection that includes the above described connection order, and triangles are formed using three contiguous points (matched polygonal forms are present). Then, as shown in a matching image 903 , a check is performed to determine whether correspondence has been established for every three points of the one-stroke line images, from the beginning, and in a case wherein the correspondence of the three points has been established, the number of matched polygons is counted. The correspondence is sequentially examined in this manner until the end point of the one-stroke line image. As a result, the matched forms are stored in a polygon array 904 , and in a case wherein the number of matched forms is equal to or greater than a threshold value for match determination, it is determined that the authentication has been successful. <Identity Match Probability> [0081] An explanation will now be given for how the match probability that was obtained in a case wherein all of the pixels were simply connected in order of (resolving) reproduction instability strength points, without repetitively passing these points, is to change in a case wherein the number of points is reduced, in correlation with the physical size of a target to be authenticated, which is obtained with the resolution of a digital imaging apparatus, and the size (pixel size) of image data that is collected by focusing. Here, two images are read as data, and the same resolution is employed. [0082] Based on the authentication method, one-stroke line images are finally changed to data representing a correlation of coordinates only, and the probability for matching the one-stroke line images by chance is given by the following expression. When the sizes of an image in the x, y and z directions after trimming are denoted by Xt, Yt and Zt, a degree of freedom for each reproduction instability element point is Xt×Yt×Zt in a case wherein the instability of the element point is uniform, and when the total of reproduction instability element points is denoted by N, a probability that an arbitrary point on image data is a reproduction instability element point is [0000] 1 X i × Y i × Z i [ Ex .  1 ] [0000] In a case for the matching of one-stroke line images, when the sizes of an image at the time of registration are X r , Y r , and Z r , and when it is assumed that the physical portions consonant with the pixels are regarded as the areas of corresponding pixels of data for another image, a match probability of the arbitrary point is [0000] N X i × Y i × Z i × 1 X r × Y r × Z r [ Ex .  2 ] [0000] In the case wherein a matched polygon is a shape formed by three points, a probability that all of the first three points are matched between the images is [0000] N X i × Y i × Z i × N - 1 ( X i × Y i × Z i ) - 1 × N - 2 ( X i × Y i × Z i ) - 2 × 1 X r × Y r × Z r × 1 ( X r × Y r × Z r ) - 1 × 1 ( X r × Y r × Z r ) - 2 [ Ex .  3 ] [0000] When this expression is employed for the second and following sets of three points, an identity match probability R for a case wherein the number of matched forms is P is [0000] R = ∏ i = 0 P - 1   { N - 3  i ( X i × Y i × Z i ) - 3  i × N - 3  i - 1 ( X i × Y i × Z i ) - 3  i - 1 × N - 3  i - 2 ( X i × Y i × Z i ) - 3  i - 2 } × ∏ i = 0 P - 1   { 1 ( X r × Y r × Z r ) - 3  i × 1 ( X r × Y r × Z r ) - 3  i - 1 × 1 ( X r × Y r × Z r ) - 3  i - 2 } [ Ex .  4 ] [0000] Further, in a case wherein the number N of reproduction instability element points connected to form a one-stroke line image is employed as the total number of pixels of image data, [0000] R = ∏ i = 0 X i × Y i × Z i - 1   { 1 ( X r × Y r × Z r ) - 3  i × 1 ( X r × Y r × Z r ) - 3  i - 1 × 1 ( X r × Y r × Z r ) - 3  i - 2 } [ Ex .  5 ] [0000] It is obvious that, as the number of points to be connected is reduced, a probability that the one-stroke line images are matched by chance is increased. When the accuracy for determination of authentication is increased, matching of a predetermined number or more of connection points should be provided as a requirement. Furthermore, when the number of contiguously matched points to form a polygon is increased from three, the number of mathematical operations in { } in [Ex. 5] is increased, and the probability of matching by chance is reduced, so that this method can also improve the authentication accuracy. Furthermore, it is self-evident that, in [Ex. 3], a probability of matching only the first and the third points is [0000] N X i × Y i × Z i × N - 1 ( X i × Y i × Z i ) - 1 × N - 2 ( X i × Y i × Z i ) - 2 × 1 X r × Y r × Z r × 1 ( X r × Y r × Z r ) - 1 [ Ex .  6 ] [0000] and a probability of matching by chance is increased. [0083] According to the example explained above while referring to FIG. 9 , a threshold value of five matches is employed for the number of matched polygons formed of three points, and when matches equal to or greater than the threshold value are found, it is determined that the authentication has failed. It should be noted that the optimal threshold value can be determined in accordance with the characteristics of a target to be authenticated, i.e., in accordance with a material type and a printing method that were employed. Example [0084] FIG. 1 is a system configuration diagram for an authentication system according to one embodiment of the present invention. An authentication system 100 , according to this embodiment, is an apparatus that includes a CPU 101 , a ROM 102 , a RAM 103 and various interfaces for external devices, to which a scanner 110 for reading a target and a display device 120 for displaying the results can be connected. Of course, a scanner for scanning a target, which is required for the present invention, may be incorporated in the apparatus, and as another function, a printer, for outputting the results, may be included, or the apparatus may be connected to a network to exchange data with a database. Specifically, this system may be employed as a dedicated apparatus for authentication, and various known system configurations for this technical field are available, such as the connection of a scanner to a mobile phone equipped with a camera, or to a laptop computer or a personal computer. [0085] FIG. 2 is a functional block diagram for the embodiment of the present invention. In this embodiment, a software program is executed by the CPU 101 to perform various functions required to realize the present invention, and the processing may also be performed for the individual functional blocks shown in FIG. 2 . That is, the processing is performed by an image reading unit 201 , for scanning a target and extracting an image, an individual difference data calculation unit 202 , for calculating individual difference data based on the obtained image, an individual difference data comparison unit 203 , for comparing the obtained individual difference data, and a determination unit 204 , for making a final determination as to whether the target should be authenticated. In this embodiment, the processing is performed by the functional blocks shown in FIG. 2 ; however, the blocks are not limited to those shown, and the functional blocks may be divided to provide more blocks, or a plurality of these functional blocks may be combined to form different functional blocks for performing the processing. [0086] The processing performed in this example will be described while referring to FIGS. 3 , 10 and 12 . In this example, since a specific target is to be compared with a target that has been registered in advance, or has been set forth as a matching target, and the authentication process, i.e., determination as to whether the two targets are matched is to be performed, it is assumed for this processing that individual difference data previously explained was obtained in advance and is stored in a specified area. The individual difference data obtained in advance may be stored in memory provided for the apparatus, such as the ROM 102 or the RAM 103 , or may be obtained from an external storage device or via a network. [0087] FIG. 3 is a flowchart showing the authentication processing performed for the embodiment of the present invention. The image reading unit 201 employs the scanner 110 to scan a target, and outputs image data (S 301 ). Since the scanner 110 employed for reading generally differs from a reading apparatus that was used to calculate individual difference data in advance, a predetermined correction is performed for the thus obtained image data to remove a reading difference (S 302 ). In this example, standard instruction data is employed to obtain, in advance, correction values that are used for normalizing the image resolving process, such as correction of the location of an imaging apparatus, etc., employed to calculate individual difference data, correction of the light-receiving color temperature for a sensor, white balance correction, ISO speed correction, lens distortion correction, correction of a chromatic aberration, concentration correction, correction of the amount of light for illumination, spectrum correction and conversion that is consonant with the type of imaging apparatus. When a filter provided using these correction values is employed for image data that is obtained, the individual pixel values of image data can be changed, and regardless of the configuration of the imaging apparatus, the reading of image data is enabled under a predetermined condition; however, the method is not thereby limited, and the exchange of correction value data may also be performed while the data are stored in a storage device, or another method well known to this technical field may be employed to generate image data. [0088] Generally, the authentication of a target can be performed by using only part of an image. FIG. 11 is a diagram for explaining the extraction process for a specific application example for the embodiment of the present invention. As shown in FIG. 11 , a label attached to a product is a target, and is one type of printed matter. As a target, an arbitrary selected area of the label is scanned twice to obtain two images, and a one-stroke line image is generated based on the two images obtained (S 303 ). Then, a one-stroke line image obtained in advance is read from the memory (S 304 ), and is compared with the one-stroke line image generated at S 303 , as shown in FIG. 12 (S 305 ). FIG. 12 is a diagram for explaining the match determination processing for the specific application example of this embodiment of the present invention. For comparison, when the connection and comparison method described above, for example, which uses polygons, and when a match is found at a predetermined probability (S 306 ), a notification that authentication was successful is transmitted (S 307 ), or when a match is not found at a predetermined probability (S 306 ), a notification that authentication failed is transmitted (S 308 ). In this example, the printed portion of a label has been employed for determination of authentication success; however, the method is not limited to this, and any other method well known to this technical field can be employed. For example, the impression of a seal, which is affixed as an indicator to a label in advance, may be employed as a target, and when color information can be obtained from a surface portion of a container, such data can be employed. [0089] In this example, the following apparatus, settings, etc., were employed, and extraction of an individual difference and authentication of the identity were performed for a medical label. A label to be authenticated was a film based label vertically 44.0 [mm]×horizontally 74.0 [mm], and neither a special ink nor a special process were provided for printing the label. A one-stroke line image was the sequence type, and the imaging equipment was a CCD digital camera having a pixel total of 10,750,000 pixels, for which the settings were manual focus, a light sensitivity of ISO 100, an aperture of F8, a shutter speed of 1/20 [s], and an image size (W×H) of 3872×2592 [pixels], and the number of times to be photographed was twice. [0090] Specifically, the following processing was performed to extract the characteristics for an individual difference. [0000] (1) As shown in FIG. 11 , a target label was set up for a photographing range of vertically 15.5 [mm]×horizontally 23.2 [mm], and was photographed twice, under the above conditions, to obtain image data for two images. (2) The two sets of image data thus obtained were trimmed to obtain like sizes, 8.7 [mm]×8.7 [mm], and optical data difference D(x,y), defined by the following expression, was calculated based on the two sets of image data. Assume that image data 1 is denoted by g1(x,y) and image data 2 is denoted by g2(x,y). X and Y are, respectively, a set of x coordinates and a set of y coordinates of image data. [0000] D  ( x , y ) ( x , y ) ∈ ( X , Y ) =  g   1 R  ( x , y ) - g   2 R  ( x , y )  +  g   1 G  ( x , y ) - g   2 G  ( x , y )  +  g   1 B  ( x , y ) - g   2 B  ( x , y )  [ Ex .  7 ] [0091] It should be noted that g1R (x, y) represents the R component of RGB values, and this applies to the other values. [0000] (3) The following conditions were employed to generate a one-stroke line image. Based on a connection in the descending order for the reproduction instability elements, the least required connection distance of 62 μm, the threshold value of 10.0 for the reproduction instability strength, and the number of connection points of 250, a one-stroke line image 1201 shown in FIG. 11 was generated by using the optical data difference obtained above. (4) The thus obtained one-stroke line image 1201 was stored in a database as individual difference characteristics of the target to be authenticated in a database, together with associated information (the settings of the apparatus employed, one-stroke line image generation conditions, etc.). (5) Under the same conditions as those in (1), the image of the target was captured two times again, and a one-stroke line image 1302 shown in FIG. 12 was also generated. (6) Based on associated information, the database was referred to for the one-stroke line image, and matching was performed, beginning with the first connection points, between the one-stroke line image 1201 retrieved from the database and the one-stroke line image 1302 generated at this time. The matching conditions were set as follows: the match shape should be formed of three points, the number of polygonal forms least required for match determination should be four. (7) The authentication result 1301 shown in FIG. 12 was obtained by matching. As shown in FIG. 12 , since the number of polygons 1303 that matched were 26, which satisfied the condition that the number of match polygonal forms should be four or more, it was determined that this one-stroke line image is identical to the one-stroke line image that was registered, and it could be ascertained that authentication of the target was successful. [0092] FIGS. 13 to 16 are diagrams for explaining another specific application example according to the embodiment of the present invention. For the example shown in FIG. 13 , a tablet is employed as a target. Generally, a mark, a name, etc., indicating the identity of a tablet is printed on the surface of the tablet. When the present invention is employed for the printed portions, the individual tablets can be identified. For example, when individual difference data is prepared during a manufacturing process, it is possible to uniquely specify a factory, and a lot and a time that individual tablets were produced, and various utilizations can be expected. Furthermore, when color information can be obtained from the surface of a tablet, identification for a tablet even without a mark, etc., being printed is enabled by employing the preset invention. [0093] A specific authentication process will be described in the same way as provided for a medical label. As shown in FIG. 13 , a white round tablet with a grey mark imprinted in a vertically 7.5 [mm]×horizontally 7.5 [mm] white background was employed. This tablet is a medicine commercially available on the market. The same imaging equipment as used for the medical label described above was employed, and as imaging conditions, only the shutter speed was changed to 1/50 [s], and the same values were employed for the other settings. Further, the number of times photographing was performed was also the same, two times. [0094] Under the above described conditions, individual difference characteristics were extracted in the following manner. [0000] (1) A target tablet was set up for a photographing range of vertically 15.5 [mm]×horizontally 23.2 [mm], and was then photographed two times, under the above described imaging conditions, and image data for two images were obtained. (2) The two sets of image data were trimmed to obtain the sizes of vertically 4.2 [mm]×horizontally 3.5 [mm], and the resultant two sets of image data were employed to obtain a digital reproduction difference in the same manner as performed for the medical label described above. (3) The tinted-glasses connection was provided to set the sequence type for forming a one-stroke line image, the descending order for connection, the least required connection distance of 63 μm, threshold value of 20.0 for the reproduction instability strength, and 250 as the number of the connection points, and based on these conditions, a one-stroke line image was generated. The obtained one-stroke line image is shown in FIG. 13 . (4) The obtained one-stroke line image and associated information were stored in a database, and authentication registration was completed. (5) Under the same conditions as those in (1), the target was photographed twice again to extract a one-stroke line image. (6) Similarly, matching was performed, beginning with the first connection points, between the currently obtained one-stroke line image and the one-stroke line image that was read from the database. The matching condition was so set that a matching shape should be formed of three points and the number of polygonal forms least required for match determination should be four. (7) The matching results are shown in FIG. 13 . The number of matching shapes is 13, which indicates that authentication was successful. [0095] An example shown in FIG. 14 is an example for which the present invention was applied for labels of Japanese rice wine, wine, etc., and a signature portion or a seal portion, for example, on a label may be employed as a specific portion to read, or even when a portion to read is not especially designated, the area to be read can be easily identified. Furthermore, scanning may also be performed while an image represented by affixing a seal on the label is employed as a target, and the authentication process may be performed. [0096] For an example shown in FIG. 15 , the printed portion of a retort-packed food is employed, and so long as a target can be read by a scanner, etc., and an image for the target can be generated, the present invention can be applied for the target, regardless of which material and which printing method is employed for the target. [0097] For an example shown in FIG. 16 , the present invention is employed for the identification of a painting, and since the overall area of the target is printed matter, an arbitrary portion is available for the use of the present invention. Further, even for such a target that has been greatly deteriorated over time, since the connection points that match at a predetermined ratio are kept and are not lost, the authentication accuracy can be maintained. [0098] In the above examples, except for a tablet, a specific portion to be employed for authentication should be designated; however, such a portion can be designated by using a method well known in this technical field, for example, by determining the right end portion in advance, or by transmitting information about an area that has been selected.
A certain amount of unique data of a target is extracted from image information that was read, and it is determined whether or not the target is valid on the basis of the extracted unique data. Processes are executed by means of an image reading unit which extracts an image by scanning a target, an individual difference data calculating unit which calculates individual difference data from the obtained image, an individual difference data comparing unit which compares the calculated individual difference data, and a determination unit which determines whether or not to grant validation.
Provide a concise summary of the essential information conveyed in the given context.
[ "[0001] This is a Divisional Application of application Ser.", "No. 13/577,798 filed Aug. 8, 2012 which is a National Phase of PCT/JP2011/000776 filed on Feb. 10, 2011.", "The disclosure of the prior application is hereby incorporated by reference herein in its entirety.", "TECHNICAL FIELD [0002] The present invention relates to an authentication system, and to a method for registering authentication information and for matching authentication information, i.e., an authentication system that extracts, from image data, characteristics inherent to a subject image, and employs the extracted characteristics, and a method for registering authentication information and for matching authentication information.", "BACKGROUND ART [0003] Various types of authentication techniques for determining whether or not a subject is an authorized target have been employed for all aspects of human behavior and activities, and since the advent of the Internet and the development of the electronic processing of information, a higher level authentication technique is required.", "As an orthodox authentication technique, an item having a unique shape, such as a seal or a signature, is provided as a marker for a subject, and at the present, technical features, such as a hologram, an embedded pattern (a watermark), a latent image, pearl ink, microprinting, luminescent ink and intaglio printing, are employed to prevent counterfeiting.", "Moreover, in accordance with the development of electronic processing, predetermined information, such as a passwords, is encrypted as secret information and employed for comparison to prevent forgeries.", "Furthermore, various biometric authentication techniques are also employed whereby biometric data unique to an individual human body, such as fingerprints, are registered in advance, so that in a case wherein authentication is required, actual biometric data are gathered by reading and authentication performed by determining whether the biometric data gathered for the case matches the registered biometric data (see, for example, patent literature 1).", "CITATION LIST Patent Literature [0000] PTL 1: Japanese Patent Laid-Open No. 2009-205393 SUMMARY OF INVENTION [0005] However, of the above described authentication techniques, a problem exists, with the technique for which a password is employed, in that since a password must be decided in advance and a user must remember the password, the amount of information involved is so extremely small that stealing or forgery of the information could be easy.", "[0006] For the technique that employs biometric data, only a human being can be employed for a determination as to whether or not a subject is an authorized subject, and basically, targets or other animals or plants can not be used.", "However, as another problem, recently, since an action for forging biometric data has occurred, the authentication technique for which biometric data is employed is not always completely safe.", "[0007] Furthermore, since most high-level authentication techniques require the advance physical or electronic attachment of authentication information to a subject, processing performed for the subject is required, so that promotion of the use of the authentication technique is hindered.", "[0008] While taking the above described conventional problems into account, one targetive of the present invention is to provide an authentication system that does not require processing for a target to be authenticated and that extracts unique data from image data representing individual characteristics of the target, which are obtained under predetermined configuration requirements, by employing a standard digital imaging apparatus having a predetermined configuration and then employing the extracted unique data to determine whether the target is an authorized target, as well as a method for registering authentication information and for matching authentication information.", "[0009] To achieve this targetive, the invention according to claim 1 is characterized by comprising: [0010] storage means for storing, as individual difference data used to uniquely identify a target to be authenticated, connected lines that are generated in such a manner that a plurality of sets of digital data are obtained by scanning and resolving the target using digital imaging means, an optical data difference is calculated at corresponding positions, designated by the digital data, midpoints for physical positions of a subject, which correspond to center positions of pixels located at the obtained corresponding positions, are calculated based on a physical size of the subject that corresponds to a pixel size of the digital imaging means, and are coupled in order, as connection points, beginning with the largest optical data difference;", "[0011] transformation value calculation means for, when the digital imaging means has obtained digital data through scanning, multiple times, the target to be authenticated under configuration requirements for the digital imaging means, comparing a plurality of sets of the thus obtained digital data, and calculating translation and rotational transformation of the individual digital data sets in order to match positions for mapping the target to be authenticated;", "and [0012] individual difference data extraction and determination means for employing the obtained translation and rotational transformation to identify correlated positions of pixel arrays of the plurality of digital data sets and to read, from the storage means, the connected lines for the individual difference data for the corresponding positions, for tracing a polygonal line to search for locations of the connection points present on the connected lines that have been read, and for calculating an optical data difference of pixels on physical pixel planes that include the locations of the connection points, and that are superimposed, and when it is determined that a predetermined relationship is established between the obtained optical data difference and the order of the connected lines, determining that authentication is successful.", "[0013] For the invention according to claim 2 , the authentication system of claim 1 is characterized in that: [0014] a resolution of the digital imaging means is included in configuration requirements for the digital imaging means;", "and [0015] the resolution of the digital imaging means is lower than a particle size used to form an image of the target to be authenticated.", "[0016] For the invention according to claim 3 , the authentication system of claim 1 or 2 is characterized in that the transformation value calculation means sequentially scans the target to be authenticated a plurality of times.", "[0017] For the invention according to claim 4 , the authentication system of one of claims 1 to 3 is characterized by further comprising: [0018] correction means for employing predesignated information to perform correction for normalizing a difference in image data caused by a difference in configuration requirements for the digital imaging means.", "[0019] The invention according to claim 5 , the authentication system of one of claims 1 to 4 is characterized in that: [0020] the storage means also stores a line connection comparison setup, including parameters and comparison methods, to be used for comparison of connected lines;", "and [0021] the individual difference data extraction and determination means employs the comparison setup stored in the storage means to trace, along a polygonal line, positions of connection points on the connected lines that have been read, and determines that authentication is successful, when the obtained optical data difference indicates, with respect to the order of connection lines, a predetermined relationship that is designated in the comparison setup.", "[0022] For the invention according to claim 6 , the authentication system of one of claims 1 to 5 is characterized in that when the obtained optical data difference indicates a descending order by a predetermined number, with respect to the order of the connection lines, the individual difference data extraction and determination means determines that authentication is successful.", "[0023] The invention according to claim 7 is an authentication information registration method, characterized by comprising: [0024] a transformation value calculation step of calculating parallel translation and rotational transformation, so that based on predetermined configuration requirements for digital imaging means, a target to be authenticated is scanned by the digital imaging means a plurality of times to obtain digital data, a plurality of sets of digital data thus obtained are compared with each other, and locations at which mapping for the target to be authenticated is performed using the digital data are matched;", "[0025] a step of employing the obtained parallel translation and rotational transformation to designate correlated locations of pixel arrays of the plurality of sets of digital data, and calculating an optical data difference for the correlated locations that are designated;", "[0026] a step of calculating a physical size for a subject, with respect to a pixel size of digital data based on configuration requirements for the digital imaging means, employing the obtained physical size to calculate, as connection points, midpoints of physical positions of the subject that correspond to the center positions of pixels that are located at the corresponding positions, coupling the connection points in the descending order, by an arbitrary number of times, beginning with the largest optical data difference, and extracting connected lines as individual difference data;", "and [0027] a registration step of registering the extracted connected lines at storage means.", "[0028] For an authentication system that includes storage means for storing, as individual difference data used to uniquely identify a target to be authenticated, connected lines that are generated in such a manner that a plurality of sets of digital data are obtained by scanning and resolving the target using digital imaging means, an optical data difference is calculated at corresponding positions, designated by the digital data, midpoints for physical positions of a subject, which correspond to center positions of pixels located at the obtained corresponding positions, are calculated based on a physical size of the subject that corresponds to a pixel size of the digital imaging means, and are coupled in order, as connection points, beginning with the largest optical data difference, the invention according to claim 8 is characterized by comprising: [0029] a transformation value calculation step of, when the digital imaging means has obtained digital data through scanning, multiple times, the target to be authenticated under configuration requirements for the digital imaging means, comparing a plurality of sets of the thus obtained digital data, and calculating translation and rotational transformation of the individual digital data sets in order to match positions for mapping the target to be authenticated;", "and [0030] an individual difference data extraction and determination step of employing the obtained translation and rotational transformation to identify correlated positions of pixel arrays of the plurality of digital data sets and to read, from the storage means, the connected lines for the individual difference data for the corresponding positions, tracing a polygonal line to search for locations of the connection points present on the connected lines that have been read, and for calculating an optical data difference of pixels on physical pixel planes that include the locations of the connection points, and that are superimposed, and when it is determined that a predetermined relationship is established between the obtained optical data difference and the order of the connected lines, determining that authentication is successful.", "BRIEF DESCRIPTION OF DRAWINGS [0031] FIG. 1 is a system configuration diagram for an authentication system according to one embodiment of the present invention;", "[0032] FIG. 2 is a functional block diagram for the embodiment of the present invention;", "[0033] FIG. 3 is a flowchart showing an authentication process performed for the embodiment of the present invention;", "[0034] FIG. 4 is a diagram for explaining the principle of the present invention;", "[0035] FIG. 5 is a diagram for explaining the processing, of the embodiment of the present invention, for extracting an individual identification pattern;", "[0036] FIG. 6 is a diagram for explaining the processing, of the embodiment of the present invention, for extracting an individual identification pattern;", "[0037] FIG. 7 is a diagram for explaining the processing, of the embodiment of the present invention, for extracting an individual identification pattern;", "[0038] FIG. 8 is a diagram for explaining the authentication processing performed, for the embodiment of the present invention, by employing an individual identification pattern that has been extracted in advance;", "[0039] FIG. 9 is a diagram for explaining an example, for the embodiment of the present invention, wherein a determination for matching is performed through the authentication processing performed by employing an individual identification pattern that has been extracted in advance;", "[0040] FIG. 10 is a diagram for explaining an example process, of the embodiment of the present invention, for correcting a target image that is extracted;", "[0041] FIG. 11 is a diagram for explaining the process for correcting a specific example for which the embodiment of the present invention is applied;", "[0042] FIG. 12 is a diagram for explaining a matching process performed for specific examples for which the embodiment of the present invention is applied;", "[0043] FIG. 13 is a diagram for explaining another specific example for which the embodiment of the present invention is applied;", "[0044] FIG. 14 is a diagram for explaining an additional specific example for which the embodiment of the present invention is applied;", "[0045] FIG. 15 is a diagram for explaining a further specific example for which the embodiment of the present invention is applied;", "[0046] FIG. 16 is a diagram for explaining yet one more specific example for which the embodiment of the present invention is applied;", "[0047] FIG. 17 is a diagram showing an example tinted-glasses connection for the embodiment of the present invention;", "[0048] FIG. 18 is a diagram showing an example connection method for a one-stroke line image according to the embodiment of the present invention;", "[0049] FIG. 19 is a diagram showing another example connection method for a one-stroke line image according to the embodiment of the present invention;", "[0050] FIG. 20 is a flowchart showing the processing for registering individual difference data according to this embodiment;", "[0051] FIG. 21 is a flowchart showing the authentication processing performed for this embodiment;", "[0052] FIG. 22 is a detailed diagram for explaining calculation of an optical data difference according to this embodiment;", "and [0053] FIG. 23 is a diagram for explaining an example, for the embodiment of the present invention, wherein determination for matching is performed through authentication processing employing an individual identification pattern that has been extracted in advance.", "DESCRIPTION OF EMBODIMENTS [0054] One embodiment for an authentication system, a method for registering authentication information, and for matching authentication information of the present invention will now be described, while referring to drawings.", "<Principle Of Individual Authentication System>", "[0055] The system of this embodiment determines the identity of a target to be authenticated, based on principles related to unique information for the target extracted from image data, which represents the characteristics of each target obtained, under predetermined configuration requirements by a standard digital imaging apparatus having a predetermined configuration, without any processing being required for the target, and based on a unique information extraction method, for extracting unique information from an image that was read, and an individual authentication method, for authenticating a target, as needed, based on the unique information that is extracted.", "Further, targets can include arbitrary materials, such as printed matter and various finished products or parts, and human bodies, so long as an image can be obtained by scanning or imaging the surface.", "<Unique Information Based on Individual Difference>", "[0056] The purpose for scanning a material that actually exists using a digital imaging apparatus, such as a scanner or a camera, is to quantize the status of the surface;", "however, the entire structure of the material to be processed can not be read.", "It can be said that scanning of the surface of the material is mapping of a phenomenon that occurs, moment by moment, on the surface of the material.", "For example, when image scanning is performed by an image sensor (CCD/CMOS) wherein light-receiving portions, such as imaging elements, which react to light of an optical wavelength (a visible light range of a short wavelength of 360 nm to 400 nm to a long wavelength of 760 nm to 830 nm) are arranged on the plane, a difference occurs in the image processing, the primary color spectroscopy and the element configuration, but reproduction for digital mapping of phenomenon is performed by a color imaging process (numerical imaging process) during which collected light is separated into RGB and others, charge reactions of the individual light-receiving portions are quantized to numerical values, and the numerical values are arranged in order and output as array data.", "The optical mapping data obtained is a numerical value replaced with the scale of a resolution that corresponds to the XYZ arrangement.", "Further, for the image sensor, when a pixel resolution is high, i.e., when the sizes of the individual light-receiving portions of the sensor are smaller than the wavelength of light, optical observation is disabled, or when the light-receiving portions are greater, observation of the material by the individual light-receiving portions is also disabled.", "Furthermore, since a natural substance is arranged at random, reconstruction of the natural substance is also impossible by using the image sensor, where the light-receiving portions are provided as arrays.", "[0057] This indicates resolving power, and image data is formed in such a manner that, when reactions have occurred relative to light received in consonance with the sizes of elements, which are scan unit areas for the image sensor, the reactions are quantized to be provided as an array, i.e., when the amount of electricity is generated in consonance with light received at the individual elements arranged in a predetermined form in the image sensor, the amount of electricity is provided as an array.", "Therefore, this quantization process is also eventually a color compression process for performing quantization for a phenomenon that occurs in one part of a target that corresponds to one scan unit area, and it can be said that image data obtained by arranging the results is a phenomenon resolved in accordance with the size of the scan unit area.", "That is, image data obtained by scanning is changed in accordance with configuration requirements, such as a resolution, and in this embodiment, this phenomenon is focused on to extract unique information for a target.", "Here, the configuration requirements are the structural and exposure requirements for an imaging apparatus, consisting of parameters that represent the physical locations, the types, the sizes, the resolutions, the lens arrangements and the lens magnifications of imaging elements, and the physical location, the luminescence, the frequency properties, the color temperature of a lighting device, such as an LED, a subject distance relative to a target to be authenticated, a focal position, a focal length, a shutter speed, a frame rate, and a positional relationship between the target to be authenticated and an optical system that includes the lenses and the imaging elements.", "[0058] Since a target for which authentication is actually to be determined is formed of a natural material, the smallest size of this material is a “particle”, which is even smaller than nano- and micro-sized.", "Photons are larger than these particles, and for visible light, since the wavelength is set in the visible light range between a short wavelength of 360 nm to 400 nm to a long wavelength of 760 nm to 830 nm, light (visible light) is not reflected at the unit area of a substance that is smaller than the above described size.", "Therefore, the phenomenon of a natural substance that is much smaller than the scale of a resolution can not be interpreted by quantization using a sensor;", "however, the reading results, i.e., the values output by the sensor are affected by the phenomenon that occurs in the unit area of that size.", "That is, when the scanning position is shifted even slightly (by micro-order), i.e., when the positions of the arrays of image data obtained by reading the same target a plurality of times are slightly shifted away from the corresponding locations of the elements of the image sensor employed for reading, the corresponding numerical values of optical data to be obtained by the elements are adversely affected, and thus, even when scanning of the same target is repeated under the same condition, the same scan data can not be obtained.", "This phenomenon always occurs so long as an image sensor that has a resolution smaller than the wavelength of light is not provided, and in this invention, a difference in the reading results is called a resolution difference.", "FIG. 4 is a diagram for explaining this difference resolution by employing a specific CCD sensor.", "It should be noted that an example shown in FIG. 4 is merely an example for which this principle is applied, and the present invention is not limited to any of the techniques specifically described in this example.", "[0059] Referring to FIG. 4 , generally, in a CCD sensor, for example, that is employed for a scanner that reads a target to be authenticated, light is split into RGB light, etc.", ", by imaging elements arranged at predetermined intervals, as illustrated, and the visible light having a wavelength (in a visible light range of a short wavelength of 360 nm to 400 nm to a long wavelength of 760 nm to 830 nm) enters the apertures of the imaging elements and are converted into electrical charges, which are then accumulated.", "The RGB visible light is digitized by employing the accumulated electrical charges as the intensity of light, and based on the numerical digital values for RGB, etc.", ", color compression is performed for incident light that is limited by the pitches and the apertures of the imaging elements, so that one color is allocated for one element, and the target to be authenticated is expressed as a color data array.", "The thus obtained color data array is expressed as numerical data that represent the coordinates for the locations of the imaging elements and the individual components, such as RGB, of the trichromatic system.", "For example, assuming that the color data array is (X coordinate, Y coordinate: R, G, B), data like (1, 1: 112, 28, 93), (1,2: 17, 30, 104), (1, 3: 39, 36, 107), .", ", are obtained, as illustrated, and these values differ from each other because each time the scanner reads the target, the scanning position is varied by micro order.", "[0060] The resolution difference also occurs for printed matter produced in a nano-size or micro-size.", "When images are obtained by scanning duplicate copies (mass-produced goods) like printed matter, there is an influence, exerted by a printing error and a difference in paper surfaces, at a nano-level or a micro-level, which can not be really observed for the actual phenomenon.", "That is, the characteristics of an individual based on nano-sized particles, which are provided without the intention, or which are not available for mass production even with the intention, are incorporated into the resolution difference.", "A difference that is generated, due to a difference between resolutions during scanning of the target, and due to the characteristics of an individual, is called an “individual difference”", "in this invention.", "<Extraction of Information Unique to Target>", "[0061] According to this invention, a difference in individuals is obtained from targets, such as printed material, although not limited to them and unique information for one target is extracted, based on the obtained individual difference, and is employed for the authentication processing.", "One such method for extracting information inherent to a target will now be explained.", "As described above, when image data are output each time scanning is employed, reproduction of the resolved images becomes unstable, and a difference in individuals is incorporated into the image data.", "However, since the values obtained simply by resolving are generally not constant, these values can not be employed as information that uniquely represents the target.", "Therefore, information for obtaining a predetermined relation is extracted from the individual difference.", "That is, the data obtained by scanning are compared, based on the corresponding positions for these data, and are rearranged in order, beginning with the data where the greatest change is made, and the positional relationship of the data is replaced by the three-dimensional coordinates, the points of which are connected in order, so that a specific polygonal line pattern, i.e., a “line”", "is generated, along which “reconstruction instability element points”, which are elements used to prevent the same image resolving due to an individual difference, are arranged in the order of strength of reconstruction instability.", "As previously described, regardless of the resolution of the sensor of the scanner, this “line”", "can always be generated by scanning the image of a target, and the order for drawing the “line”", "includes predetermined universality based on the uniqueness of the information that is inherent to the target.", "[0062] Since the order for drawing the line is the order in which reproduction instability occurs, specifically, this order can be obtained in such a manner that the same target is scanned at least twice, and the ranking that represents differences in the scanning results is specified.", "According to the fundamental principle of the present invention, while there is a problem that, each time a target is scanned, the same results are not always obtained, depending on physical conditions (the wavelength and property of light), and for mass-produced goods, such as printed material, only an identification of the type is enabled by a comparison of the obtained individual difference and identification of an individual is difficult, this problem can be resolved by using a more specific method, whereby, instead of performing a comparison of individual differences, the ranking for instability for image reproduction is observed for each array that is scanned, in order to enable identification of an individual.", "This can be realized based on the fact that a target physically exists and the fact that the arrays of the image sensor are physically present.", "That is, the arrangement of the image sensor is physically constant, and since the probability that the internal structure of the image sensor will be adversely affected when a scanning position is shifted for each scanning is at least lower than the probability that shifting will occur in the scanning position, it can be assumed that the arrays of the image sensor be maintained in the original configuration state.", "Therefore, in the “line”", "pattern obtained from image data (array values) in the scanned area, the positional relationship is maintained.", "That is, for the individual elements of the image sensor, the values are changed for each scanning, but the order of differences is maintained.", "Further, when different printed matter, for example, is employed as a target and is scanned along the above described “line”", "pattern, a probability of matching is low, and a probability, which will be described later, is obtained based on the number of “reproduction instability element points”, so that determination of authentication can be appropriately performed.", "Since the “line pattern”", "represents image resolving instability, i.e., expresses the degree of instability as to the values that are obtained for image data by the corresponding elements, the line pattern also indicates the order at which reproduction instability occurs.", "In this case, since it is simply required that the “line pattern”", "express the degree of instability for reproduction, the line pattern can be obtained by scanning the same target sequentially at least twice, and employing the ranking for differences of the scanning results.", "That is, image data obtained by sequentially scanning twice, for example, differ slightly from each other, because of the characteristics of the target that are smaller (finer) than the resolution level employed for scanning, and when these differences are processed based on the concept, such as the ranking, the detailed characteristics of the target can be obtained.", "In this case, scanning is generally sequentially repeated twice, i.e., performed within a predetermined period of time, because when a time interval is too long, a phenomenon that has occurred in the target is greatly changed, and the above described principle might not become effective.", "For example, in a case wherein the power of the imaging apparatus is turned off after the first photographing was performed, the imaging conditions are greatly changed due to non-reversibility for the amount of electric charges in the image sensor and the sensitivity to the amount of light, and there is a probability that adjustment for the conditions will be difficult.", "Therefore, it is preferable that photographing multiple times be performed within a predetermined contiguous period, or be continuously performed in the state wherein almost the same photographing conditions are maintained.", "According to the principle of the present invention described above, no new apparatus is required, while a phenomenon that can not be captured in a single image resolving process is estimated by employing a plurality of sets of image data, and a phenomenon of a target beyond the resolving power of the image sensor can be obtained.", "[0063] One process for extracting information inherent to a target will now be described by employing the above described principle.", "Referring to FIG. 5 , as explained while referring to FIG. 4 , a camera 501 where a CCD or CMOS image sensor is mounted sequentially scans a target 502 multiple times under the same configuration requirements, and obtains digital data.", "FIG. 20 is a flowchart showing the processing for registering individual difference data according to this embodiment.", "[0064] Since a different imaging apparatus might also be employed for authentication, standard instruction data are employed to obtain, in advance, correction values for normalizing the image resolving process, i.e., for performing a sight defect correction, such as a correction of the location of an imaging apparatus, etc.", ", employed to calculate individual difference data, corrections of a resolution and the light-receiving color temperature for a sensor, white balance correction, ISO speed correction, lens distortion correction, correction of chromatic aberration, concentration correction, correction of the amount of light for illumination, spectrum correction and conversion that is consonant with the type of an imaging apparatus.", "A filter provided for using these correction values is employed for the obtained image data.", "With this arrangement, the individual pixel values of image data can be changed, and regardless of the configuration of the imaging apparatus, the reading of image data is enabled under a predetermined condition;", "however, the method is not limited to this, and the exchange of data representing correction values may also be performed while the data are stored in a storage device, or another method well known for this technical field may be employed to generate image data.", "For example, in a case wherein different imaging apparatuses are employed for registration and for authentication, the resolution may be stored in advance, and when low-resolution image data is to be processed, the resolution of the low-resolution image data may be changed to the same level by being increased (the amount of data becomes greater as the resolution is increased, while the numerical value is unchanged), or decreased.", "[0065] The same images 512 and 522 are actually captured for the target by the first scan and second scan;", "however, when image data 511 obtained the first time and the image data 521 obtained the second time are compared, it is understood that different array data are obtained due to a slight difference in the scanning positions of a scanner.", "Specifically, compared with the array of the image data 511 obtained during the first scan, (1,1: 112, 28, 93) (2,1: 17, 30, 104) (3,1: 39, 36, 107) (4,1: 221, 38, 108), .", ", the array of the image data obtained by the second scan slightly differs, which is (1,1: 110, 45, 99) (2,1: 28, 24, 167)(3,1: 35, 41, 100)(4,1: 209, 43, 111), .", "[0066] Then, a resolution difference is extracted from a plurality of image data sets obtained by scanning the target multiple times in the above described manner.", "Specifically, as shown in FIG. 6 , a plurality of sets, two sets in this case, i.e., image data 601 and 602 are employed to extract a differential image 603 , and a resolution difference that occurs when image resolving is performed multiple times is regarded as an optical data difference, and is employed to reveal an individual difference.", "In a case wherein a resolution difference is to be calculated, comparison of different points is meaningless, and transformation values for translation and rotation for the individual sets of image data are calculated to align the positions where the same portion of the subject is to be mapped.", "The transformation values obtained for the image data are employed to superimpose the pixel arrays of the individual sets of image data, and optical data of pixels at the aligned positions are compared to calculate an optical data difference.", "Any well known method for this technical field can be employed for the calculation of the transformation values for aligning the positions.", "[0067] For calculation of these transformation values, for example, several characteristic points may be extracted from the individual sets of image data, and affine transformation, for example, may be performed to match these characteristic points;", "however, the calculation method is not limited to this.", "In this embodiment, for a comparison of a plurality of sets of image data, points correlated with each other are designated, and transformation values are calculated, which indicate how translations, such as parallel shifts, or rotations should be performed for image data in order to superimpose the points;", "however, instead of actually changing image data to overlay, the transformation values are employed to specify corresponding points, and a difference of optical data is obtained for pixels located at the corresponding points.", "This is because there is a probability that, when image data are superimposed by actually performing transformation, a slight shift occurs.", "Therefore, so long as such a shift can be avoided, it may actually be possible for the transformation process to be performed for the image data, following which a difference is calculated and the above processing is performed.", "[0068] FIG. 22 is a diagram for explaining a detailed example for this embodiment for calculating an optical data difference.", "As described above, according to this embodiment, transformation is performed for image data that are obtained by scanning a target multiple times, so that the positions of image data where mapping of a subject is performed are aligned, and the optical data for the individual pixels that are correlated with each other are compared to obtain an optical data difference.", "Specifically, this operation can be performed through the processing shown in FIG. 22 .", "First, transformation values for image data A 2201 and image data B 2202 are calculated so as to align the positions for mapping a subject.", "Then, the image data A and B are transformed, the obtained optical data for corresponding pixels (RBG components in this example) are compared, and a difference of the optical data is employed as an optical data difference for the corresponding physical positions.", "More specifically, virtual image data P 2203 shown in FIG. 22 is prepared (thus, the size of the image data P is smaller than that of the image data A or B), and the individual points of the image data A and B are obtained based on the corresponding points of image data P 2203 .", "As shown in enlarged image data portions A 2205 and B 2206 , the pixels of the image data A and B do not completely match when the data are superimposed, and a specific pixel in the image data A 2205 overlaps a plurality of pixels in the image data B 2206 .", "[0069] Therefore, in this embodiment, for example, for acquisition of an optical data difference, a difference is calculated between an optical data value for one pixel and optical data values of a plurality of pixels that overlap that pixel;", "however, the method is not limited to this, and any other well known method in this technical field can be employed for calculation.", "In this case, a connection point that will be described later can be a midpoint 2211 of a center point 2209 of one pixel and a center 2210 of center points of corresponding multiple pixels.", "As a result of calculation, the image of the obtained optical data difference is expressed using color.", "It should be noted that, in actuality, the above described intermediate process is not present, and a one-stroke line pattern is directly obtained based on data for the optical data difference.", "When the individual component values are added together, the obtained total value is regarded as an optical data difference with respect to the image data A and B. [0070] In this manner, the resolution difference can be represented as a phase difference at the position where corresponding images are superimposed, by employing, for example, the sum of the absolute values of the differences for the individual RGB components at each image superimposition position, as shown in FIG. 6 .", "Here, since as described above the superimposition positions of pixels of the image data 601 and 602 should be identified in order to obtain a difference between the image data 601 and 602 , the individual characteristic points of the individual image data sets are employed to specify in advance the corresponding positions to superimpose, so that optical data for the same portion of a subject can be compared with each other.", "As a result of such superimposition, the individual pixel values that correspond to the physical positions of the image data A 601 and B 602 are compared for each of the RGB components, and the obtained difference is expressed using color as an optical data difference C. That is, for the image data 601 , when array A (1,1: 112, 28, 93) (2,1: 17, 30, 104) (3,1: 39, 36, 107) (4,1: 221, 38, 108) .", "and array B (1,1: 110, 45, 99)(2,1: 28, 24, 167) (3,1: 35, 41, 100)(4,1: 209, 43, 111) .", "are converted into actual distances, A′ (0.009, 5.391, 0.0: 112, 28, 93) (0.027, 5.391, 0.0: 17, 30, 104) (0.045, 5.391, 0.0: 39, 36, 107) (0.063, 5.391, 0.0: 221, 38, 108) .", "(coordinate unit of μm) and B′ (0.011, 5.392, 0.0: 110, 45, 99) (0.031, 5,392, 0.0: 28, 24, 167)(0.048, 5.392, 0.0: 35, 41, 100)(0.066, 5.392, 0.0: 209, 43, 111).", "A′(+)B′=CB′ (0.011, 5,392, 0.0: 110, 45, 99) (0.031, 5.392, 0.0: 28, 24, 167)(0.048, 5.392, 0.0: 35, 41, 100) (0.066, 5.392, 0.0: 209, 43, 111).", "[0071] The resolution difference thus obtained includes an attribute unique to a target because characteristics inherent to the target are incorporated, and a predetermined correlation exists for the results that are extracted by scanning the same target multiple times.", "In order to make this relationship more apparent, i.e., to enable authentication of the target, the obtained resolution difference is employed to connect the reproduction instability element points.", "That is, based on the resolution difference, the reproduction instability element points are arranged in the descending order of the reproduction instability strength, i.e., the midpoints of the individual superimposition positions in the above described example are arranged in order beginning with the greatest value of an optical data difference, and this order represents reproducibility with respect to the image resolving process of a target to be photographed, i.e., a predetermined correlation is established about the same target.", "Compared with an individual difference, the numerical value of the reproduction instability strength, i.e., the optical data difference for the individual sets of image data, is more adversely affected by an error that occurs during the image resolving process, and therefore, is not appropriate as information unique to a target.", "Therefore, the points are rearranged and connected in order, while the numerical value of the reproduction instability strength is disregarded and only the positional information is taken into account.", "For positional information, the size of imaging elements, which are constituents of an imaging apparatus, and configuration information of an optical system, such as the lens structure and a subject distance, are employed, and the physical size of a subject that corresponds to the pixel size of image data is calculated based on the positions of pixels that are superimposed, and then, the midpoint of the physical mapping positions for the center points of pixels that are superimposed is obtained, so that the positional information is employed to support a case, for example, wherein the ratio of the size of image data to the size of a subject is changed when the configuration of an imaging apparatus differs for registration and for authentication.", "[0072] Specifically, as shown in FIG. 7 , the transformation values of the individual image data sets, which have been superimposed to obtain the optical data difference in FIG. 6 , are employed to change the superimposed pixel positions to the physical positions (three-dimensional positions) of a subject, which is mapped at the pixel center point, and the midpoints of these physical positions are employed as positional information of the individual connection points along connected lines in a polygonal line pattern that represents an individual difference.", "Optical data differences 701 D (25) (80) (16) (20) .", "are rearranged in the order of the values of optical data differences, and A′ (3.353, 0.072, 0.0) (1.771, 0.960, 0.0) (5.295, 5.245, 0.0)(4.276, 0.928, 0.0) .", "and B′ (3.357, 0.072, 0.0)(1.773, 0.963, 0.0)(5.292, 5.247, 0.0) (4.275, 0.927, 0.0) .", "are obtained, which are physical positions of a subject that is mapped at the center positions of corresponding pixels for the first two image data sets that are employed for calculation of difference values.", "When positional information of the midpoint (the averaged position for the X, Y and Z axes) is L(3.355, 0.072, 0.0) (1.772, 0.9615, 0.0) (5.2935, 5.246, 0.0)(4.2755, 0.9275, 0.0) .", ", connected lines as shown in an image 702 are generated, which represent an individual difference obtained from the image data in the scan area.", "Here, connected lines or an image representing these connected lines is called a one-stroke line image.", "As will be described later, the obtained one-stroke line image provides the order for reproducibility, which can not be obtained by a single image resolving process, and represents characteristics unique to a target.", "[0073] Through the above processing, it is possible to obtain data relative to connection of reproduction instability element points, which is individual difference data extracted based on a difference between individuals included in data obtained by scanning a target, and in this embodiment, the individual difference data is employed to perform authentication of the identify of a target.", "However, the individual difference data and the extraction method described above are merely representative examples for the present invention, and so long as information is inherent to a target and is incorporated to a resolution difference in image data obtained by scanning a target, such information can be extracted by using an arbitrary method well known in this technical field, and can be employed as individual difference data for this invention.", "Furthermore, in the above described description, the RGB component values are employed;", "however, as is apparent from the principle of the present invention, any data can be employed so long as the data is obtained by optically scanning the state of the surface of a target at a predetermined resolution, and consists of arrays representing the intensity of light for each scan unit area.", "<Target Authentication Process>", "[0074] While referring to FIGS. 8 , 10 and 23 , an explanation will be given for a method for authenticating a target based on individual difference data obtained above, i.e., a method for employing individual difference data to determine whether a target, such as printed matter, matches a target from which individual difference data was already extracted.", "First, an explanation will be given for a precondition that predetermined similarity is established in a case wherein reproducibility in the order of the reproduction instability element points, i.e., the positional information of the connection points is arranged for the same target, in the order of the strength of optical data difference, beginning with the greatest value.", "FIG. 21 is a flowchart showing the authentication processing performed for this embodiment.", "[0075] As shown in FIG. 8 , image data is obtained in advance by reading a target 502 using a scanner, etc.", ", multiple times, and individual difference data, represented by connecting lines in an image 801 , is extracted and stored in some storage means, such as a database.", "In this case, the target is further scanned by the camera 501 multiple times, and as shown in an image 802 , the one-stroke line pattern in the image 801 extracted in advance is employed to overlay the pixels at the connection positions of the one-stroke line pattern, and an optical data difference is obtained at the positions corresponding to the pixels, or specifically, the connection positions are compared in the order of connecting lines.", "As a result of comparison, since the individual difference is reflected in the resolution difference, the one-stroke line images do not completely match, as shown in FIG. 8 ;", "however, as for the points of a one-stroke line pattern of the image 801 and those of the image 802 , predetermined reproducibility is established for the order of reproduction instability element points and a one-stroke line pattern 803 can be obtained.", "Therefore, for one-stroke line patterns obtained for the same target, since reproducibility is present in the order in which the corresponding points are connected, the degree of matching for the order can be employed to determine the identify of an individual.", "[0076] Here, in this embodiment, matching for a target is performed by comparing the positions of the connection points that are arranged in the descending order of the strengths of differential optical data;", "however, a method for comparison of one-stroke line images is not limited to this method, and various pattern comparison methods, i.e., variations on the connection comparison method, are available, such as a method for coupling the points in order, beginning with the lowest level of the reproduction instability element strength, and comparing these points.", "In a case wherein the present invention method is employed, since a limitation of a target to be authenticated is enabled by using parameters and a comparison method that are appropriate for a target to be captured, these parameters and a comparison method are together called a tinted-glasses connection, or a connection and comparison setup.", "For a tinted-glasses connection, the following various parameters are employed, and a connection type for a one-stroke line image is determined in accordance with a set of the parameters.", "An example for the tinted-glasses connection is shown in FIG. 17 .", "Further, the connection types for a one-stroke line image are shown in FIGS. 18 and 19 .", "In FIG. 18 the index type is shown, and in FIG. 19 the sequence type is shown.", "The parameters employed for the tinted-glasses connection are: ((the order (forward or reverse) of reproduction instability element strengths)(the least required connection distance)(the threshold strength value)(change in strength)(the number of connection points)(the scan area size)+α)).", "[0077] Further, a one-stroke line image formation example that corresponds to these parameters is as follows.", "[0000] Index type “one-stroke line image”: ((starting point: three dimensional Cartesian coordinates XYZ) (starting point: a three dimensional vector) (a distance)+the number of points×((a three dimensional vector) (a distance)) Sequence type “one-stroke line image”: The number of points×three dimensional Cartesian coordinates XYZ [0078] That is, various comparison methods can be employed, such as one for employing the ascending order, instead of the descending order, which will be described in detail below, one for skipping reproduction instability element points, for which the distances do not reach the least required connection distance, one for skipping elements, for which the change in strength is equal to or lower than a predetermined level, one for connecting points until the number of connection points reaches the maximum value, or one for connecting points only within the range of a designated area.", "Furthermore, the most appropriate tinted-glasses connection can be employed in accordance with a material on which a target is presented and a method for representing the target, i.e., a printing method and an ink type used for the target, and it is also required for the actual authentication process to determine in advance which tinted-glasses connection should be employed.", "Therefore, in a database, etc.", ", used to store individual difference data described above, associated information concerning tinted-glasses connections to be employed is stored in correlation with the individual difference data by using a predetermined method, so that the authentication process can be performed, based on the individual difference data, under optimal conditions.", "The associated information can include not only information for the tinted-glasses connection, but also other useful information employed when the identity of an individual is to be determined based on the individual difference data.", "[0079] Next, a method for determining the identity, i.e., a method for determining reproducibility for the order of reproduction instability element points, will be described.", "A specific process example shown in FIG. 23 is employed for this explanation.", "For match determination for a target to be authenticated, first, a one-stroke line pattern 2301 extracted and registered at first is traced along the connection order to examine whether a predetermined relationship has been established for the differential values of optical data of pixels, for which the individual connection positions correspond to the physical portions of the pixels of image data 2302 that have been obtained and superimposed for authentication.", "In this case, match determination is performed by using a comparison method defined based on the tinted-glasses connection.", "For example, in a case wherein a matched polygonal shape is formed of three points, every three connection points of the one-stroke line pattern, from the beginning, are examined to determine whether the order relation is established for the corresponding points, and when the correspondence of the three points is established, the pertinent polygon is regarded as a matched form to increment the number of polygonal shapes.", "Then, examination for the correspondence relation is sequentially performed until the end point of the one-stroke line image.", "As a result, matched forms are stored in a matched polygon array, and in a case wherein the number of matched forms is equal to or greater than a threshold value for match determination, it is determined that authentication has been successful.", "Of course, a search of matched polygons may also be performed until a predetermined count is reached, and when the count value goes beyond the predetermined count, it may be assumed that authentication has successful and that the processing may be terminated.", "[0080] In this embodiment, during the authentication process, instead of generating connected lines, the connected lines that were registered are traced for image data obtained by scanning for authentication, and the number of matched sequences are counted.", "However, during the authentication process, connected lines may also be generated and be compared with each other to determine the identify.", "A specific matching process using polygons will now be described while referring to FIG. 9 .", "Specifically, as a method for comparing one-stroke line images, every three points of each one-stroke line image, from the beginning, are employed to obtain a correlation of them, and when three points of two image are matched, it is assumed that a matched polygon is present, and the number of matched polygons is incremented to determine the identity.", "Matching using polygons is also performed by comparing a one-stroke line pattern indicated by an image 902 , which represents individual difference data that was again extracted at the time of authentication, with a one-stroke line pattern indicated by an image 901 , which represents individual difference data that was extracted and registered first.", "Comparison and match determination for the two one-stroke line patterns are performed in accordance with one tinted-glasses connection that includes the above described connection order, and triangles are formed using three contiguous points (matched polygonal forms are present).", "Then, as shown in a matching image 903 , a check is performed to determine whether correspondence has been established for every three points of the one-stroke line images, from the beginning, and in a case wherein the correspondence of the three points has been established, the number of matched polygons is counted.", "The correspondence is sequentially examined in this manner until the end point of the one-stroke line image.", "As a result, the matched forms are stored in a polygon array 904 , and in a case wherein the number of matched forms is equal to or greater than a threshold value for match determination, it is determined that the authentication has been successful.", "<Identity Match Probability>", "[0081] An explanation will now be given for how the match probability that was obtained in a case wherein all of the pixels were simply connected in order of (resolving) reproduction instability strength points, without repetitively passing these points, is to change in a case wherein the number of points is reduced, in correlation with the physical size of a target to be authenticated, which is obtained with the resolution of a digital imaging apparatus, and the size (pixel size) of image data that is collected by focusing.", "Here, two images are read as data, and the same resolution is employed.", "[0082] Based on the authentication method, one-stroke line images are finally changed to data representing a correlation of coordinates only, and the probability for matching the one-stroke line images by chance is given by the following expression.", "When the sizes of an image in the x, y and z directions after trimming are denoted by Xt, Yt and Zt, a degree of freedom for each reproduction instability element point is Xt×Yt×Zt in a case wherein the instability of the element point is uniform, and when the total of reproduction instability element points is denoted by N, a probability that an arbitrary point on image data is a reproduction instability element point is [0000] 1 X i × Y i × Z i [ Ex .", " 1 ] [0000] In a case for the matching of one-stroke line images, when the sizes of an image at the time of registration are X r , Y r , and Z r , and when it is assumed that the physical portions consonant with the pixels are regarded as the areas of corresponding pixels of data for another image, a match probability of the arbitrary point is [0000] N X i × Y i × Z i × 1 X r × Y r × Z r [ Ex .", " 2 ] [0000] In the case wherein a matched polygon is a shape formed by three points, a probability that all of the first three points are matched between the images is [0000] N X i × Y i × Z i × N - 1 ( X i × Y i × Z i ) - 1 × N - 2 ( X i × Y i × Z i ) - 2 × 1 X r × Y r × Z r × 1 ( X r × Y r × Z r ) - 1 × 1 ( X r × Y r × Z r ) - 2 [ Ex .", " 3 ] [0000] When this expression is employed for the second and following sets of three points, an identity match probability R for a case wherein the number of matched forms is P is [0000] R = ∏ i = 0 P - 1   { N - 3  i ( X i × Y i × Z i ) - 3  i × N - 3  i - 1 ( X i × Y i × Z i ) - 3  i - 1 × N - 3  i - 2 ( X i × Y i × Z i ) - 3  i - 2 } × ∏ i = 0 P - 1   { 1 ( X r × Y r × Z r ) - 3  i × 1 ( X r × Y r × Z r ) - 3  i - 1 × 1 ( X r × Y r × Z r ) - 3  i - 2 } [ Ex .", " 4 ] [0000] Further, in a case wherein the number N of reproduction instability element points connected to form a one-stroke line image is employed as the total number of pixels of image data, [0000] R = ∏ i = 0 X i × Y i × Z i - 1   { 1 ( X r × Y r × Z r ) - 3  i × 1 ( X r × Y r × Z r ) - 3  i - 1 × 1 ( X r × Y r × Z r ) - 3  i - 2 } [ Ex .", " 5 ] [0000] It is obvious that, as the number of points to be connected is reduced, a probability that the one-stroke line images are matched by chance is increased.", "When the accuracy for determination of authentication is increased, matching of a predetermined number or more of connection points should be provided as a requirement.", "Furthermore, when the number of contiguously matched points to form a polygon is increased from three, the number of mathematical operations in { } in [Ex.", "5] is increased, and the probability of matching by chance is reduced, so that this method can also improve the authentication accuracy.", "Furthermore, it is self-evident that, in [Ex.", "3], a probability of matching only the first and the third points is [0000] N X i × Y i × Z i × N - 1 ( X i × Y i × Z i ) - 1 × N - 2 ( X i × Y i × Z i ) - 2 × 1 X r × Y r × Z r × 1 ( X r × Y r × Z r ) - 1 [ Ex .", " 6 ] [0000] and a probability of matching by chance is increased.", "[0083] According to the example explained above while referring to FIG. 9 , a threshold value of five matches is employed for the number of matched polygons formed of three points, and when matches equal to or greater than the threshold value are found, it is determined that the authentication has failed.", "It should be noted that the optimal threshold value can be determined in accordance with the characteristics of a target to be authenticated, i.e., in accordance with a material type and a printing method that were employed.", "Example [0084] FIG. 1 is a system configuration diagram for an authentication system according to one embodiment of the present invention.", "An authentication system 100 , according to this embodiment, is an apparatus that includes a CPU 101 , a ROM 102 , a RAM 103 and various interfaces for external devices, to which a scanner 110 for reading a target and a display device 120 for displaying the results can be connected.", "Of course, a scanner for scanning a target, which is required for the present invention, may be incorporated in the apparatus, and as another function, a printer, for outputting the results, may be included, or the apparatus may be connected to a network to exchange data with a database.", "Specifically, this system may be employed as a dedicated apparatus for authentication, and various known system configurations for this technical field are available, such as the connection of a scanner to a mobile phone equipped with a camera, or to a laptop computer or a personal computer.", "[0085] FIG. 2 is a functional block diagram for the embodiment of the present invention.", "In this embodiment, a software program is executed by the CPU 101 to perform various functions required to realize the present invention, and the processing may also be performed for the individual functional blocks shown in FIG. 2 .", "That is, the processing is performed by an image reading unit 201 , for scanning a target and extracting an image, an individual difference data calculation unit 202 , for calculating individual difference data based on the obtained image, an individual difference data comparison unit 203 , for comparing the obtained individual difference data, and a determination unit 204 , for making a final determination as to whether the target should be authenticated.", "In this embodiment, the processing is performed by the functional blocks shown in FIG. 2 ;", "however, the blocks are not limited to those shown, and the functional blocks may be divided to provide more blocks, or a plurality of these functional blocks may be combined to form different functional blocks for performing the processing.", "[0086] The processing performed in this example will be described while referring to FIGS. 3 , 10 and 12 .", "In this example, since a specific target is to be compared with a target that has been registered in advance, or has been set forth as a matching target, and the authentication process, i.e., determination as to whether the two targets are matched is to be performed, it is assumed for this processing that individual difference data previously explained was obtained in advance and is stored in a specified area.", "The individual difference data obtained in advance may be stored in memory provided for the apparatus, such as the ROM 102 or the RAM 103 , or may be obtained from an external storage device or via a network.", "[0087] FIG. 3 is a flowchart showing the authentication processing performed for the embodiment of the present invention.", "The image reading unit 201 employs the scanner 110 to scan a target, and outputs image data (S 301 ).", "Since the scanner 110 employed for reading generally differs from a reading apparatus that was used to calculate individual difference data in advance, a predetermined correction is performed for the thus obtained image data to remove a reading difference (S 302 ).", "In this example, standard instruction data is employed to obtain, in advance, correction values that are used for normalizing the image resolving process, such as correction of the location of an imaging apparatus, etc.", ", employed to calculate individual difference data, correction of the light-receiving color temperature for a sensor, white balance correction, ISO speed correction, lens distortion correction, correction of a chromatic aberration, concentration correction, correction of the amount of light for illumination, spectrum correction and conversion that is consonant with the type of imaging apparatus.", "When a filter provided using these correction values is employed for image data that is obtained, the individual pixel values of image data can be changed, and regardless of the configuration of the imaging apparatus, the reading of image data is enabled under a predetermined condition;", "however, the method is not thereby limited, and the exchange of correction value data may also be performed while the data are stored in a storage device, or another method well known to this technical field may be employed to generate image data.", "[0088] Generally, the authentication of a target can be performed by using only part of an image.", "FIG. 11 is a diagram for explaining the extraction process for a specific application example for the embodiment of the present invention.", "As shown in FIG. 11 , a label attached to a product is a target, and is one type of printed matter.", "As a target, an arbitrary selected area of the label is scanned twice to obtain two images, and a one-stroke line image is generated based on the two images obtained (S 303 ).", "Then, a one-stroke line image obtained in advance is read from the memory (S 304 ), and is compared with the one-stroke line image generated at S 303 , as shown in FIG. 12 (S 305 ).", "FIG. 12 is a diagram for explaining the match determination processing for the specific application example of this embodiment of the present invention.", "For comparison, when the connection and comparison method described above, for example, which uses polygons, and when a match is found at a predetermined probability (S 306 ), a notification that authentication was successful is transmitted (S 307 ), or when a match is not found at a predetermined probability (S 306 ), a notification that authentication failed is transmitted (S 308 ).", "In this example, the printed portion of a label has been employed for determination of authentication success;", "however, the method is not limited to this, and any other method well known to this technical field can be employed.", "For example, the impression of a seal, which is affixed as an indicator to a label in advance, may be employed as a target, and when color information can be obtained from a surface portion of a container, such data can be employed.", "[0089] In this example, the following apparatus, settings, etc.", ", were employed, and extraction of an individual difference and authentication of the identity were performed for a medical label.", "A label to be authenticated was a film based label vertically 44.0 [mm]×horizontally 74.0 [mm], and neither a special ink nor a special process were provided for printing the label.", "A one-stroke line image was the sequence type, and the imaging equipment was a CCD digital camera having a pixel total of 10,750,000 pixels, for which the settings were manual focus, a light sensitivity of ISO 100, an aperture of F8, a shutter speed of 1/20 [s], and an image size (W×H) of 3872×2592 [pixels], and the number of times to be photographed was twice.", "[0090] Specifically, the following processing was performed to extract the characteristics for an individual difference.", "[0000] (1) As shown in FIG. 11 , a target label was set up for a photographing range of vertically 15.5 [mm]×horizontally 23.2 [mm], and was photographed twice, under the above conditions, to obtain image data for two images.", "(2) The two sets of image data thus obtained were trimmed to obtain like sizes, 8.7 [mm]×8.7 [mm], and optical data difference D(x,y), defined by the following expression, was calculated based on the two sets of image data.", "Assume that image data 1 is denoted by g1(x,y) and image data 2 is denoted by g2(x,y).", "X and Y are, respectively, a set of x coordinates and a set of y coordinates of image data.", "[0000] D  ( x , y ) ( x , y ) ∈ ( X , Y ) =  g   1 R  ( x , y ) - g   2 R  ( x , y )  +  g   1 G  ( x , y ) - g   2 G  ( x , y )  +  g   1 B  ( x , y ) - g   2 B  ( x , y )  [ Ex .", " 7 ] [0091] It should be noted that g1R (x, y) represents the R component of RGB values, and this applies to the other values.", "[0000] (3) The following conditions were employed to generate a one-stroke line image.", "Based on a connection in the descending order for the reproduction instability elements, the least required connection distance of 62 μm, the threshold value of 10.0 for the reproduction instability strength, and the number of connection points of 250, a one-stroke line image 1201 shown in FIG. 11 was generated by using the optical data difference obtained above.", "(4) The thus obtained one-stroke line image 1201 was stored in a database as individual difference characteristics of the target to be authenticated in a database, together with associated information (the settings of the apparatus employed, one-stroke line image generation conditions, etc.).", "(5) Under the same conditions as those in (1), the image of the target was captured two times again, and a one-stroke line image 1302 shown in FIG. 12 was also generated.", "(6) Based on associated information, the database was referred to for the one-stroke line image, and matching was performed, beginning with the first connection points, between the one-stroke line image 1201 retrieved from the database and the one-stroke line image 1302 generated at this time.", "The matching conditions were set as follows: the match shape should be formed of three points, the number of polygonal forms least required for match determination should be four.", "(7) The authentication result 1301 shown in FIG. 12 was obtained by matching.", "As shown in FIG. 12 , since the number of polygons 1303 that matched were 26, which satisfied the condition that the number of match polygonal forms should be four or more, it was determined that this one-stroke line image is identical to the one-stroke line image that was registered, and it could be ascertained that authentication of the target was successful.", "[0092] FIGS. 13 to 16 are diagrams for explaining another specific application example according to the embodiment of the present invention.", "For the example shown in FIG. 13 , a tablet is employed as a target.", "Generally, a mark, a name, etc.", ", indicating the identity of a tablet is printed on the surface of the tablet.", "When the present invention is employed for the printed portions, the individual tablets can be identified.", "For example, when individual difference data is prepared during a manufacturing process, it is possible to uniquely specify a factory, and a lot and a time that individual tablets were produced, and various utilizations can be expected.", "Furthermore, when color information can be obtained from the surface of a tablet, identification for a tablet even without a mark, etc.", ", being printed is enabled by employing the preset invention.", "[0093] A specific authentication process will be described in the same way as provided for a medical label.", "As shown in FIG. 13 , a white round tablet with a grey mark imprinted in a vertically 7.5 [mm]×horizontally 7.5 [mm] white background was employed.", "This tablet is a medicine commercially available on the market.", "The same imaging equipment as used for the medical label described above was employed, and as imaging conditions, only the shutter speed was changed to 1/50 [s], and the same values were employed for the other settings.", "Further, the number of times photographing was performed was also the same, two times.", "[0094] Under the above described conditions, individual difference characteristics were extracted in the following manner.", "[0000] (1) A target tablet was set up for a photographing range of vertically 15.5 [mm]×horizontally 23.2 [mm], and was then photographed two times, under the above described imaging conditions, and image data for two images were obtained.", "(2) The two sets of image data were trimmed to obtain the sizes of vertically 4.2 [mm]×horizontally 3.5 [mm], and the resultant two sets of image data were employed to obtain a digital reproduction difference in the same manner as performed for the medical label described above.", "(3) The tinted-glasses connection was provided to set the sequence type for forming a one-stroke line image, the descending order for connection, the least required connection distance of 63 μm, threshold value of 20.0 for the reproduction instability strength, and 250 as the number of the connection points, and based on these conditions, a one-stroke line image was generated.", "The obtained one-stroke line image is shown in FIG. 13 .", "(4) The obtained one-stroke line image and associated information were stored in a database, and authentication registration was completed.", "(5) Under the same conditions as those in (1), the target was photographed twice again to extract a one-stroke line image.", "(6) Similarly, matching was performed, beginning with the first connection points, between the currently obtained one-stroke line image and the one-stroke line image that was read from the database.", "The matching condition was so set that a matching shape should be formed of three points and the number of polygonal forms least required for match determination should be four.", "(7) The matching results are shown in FIG. 13 .", "The number of matching shapes is 13, which indicates that authentication was successful.", "[0095] An example shown in FIG. 14 is an example for which the present invention was applied for labels of Japanese rice wine, wine, etc.", ", and a signature portion or a seal portion, for example, on a label may be employed as a specific portion to read, or even when a portion to read is not especially designated, the area to be read can be easily identified.", "Furthermore, scanning may also be performed while an image represented by affixing a seal on the label is employed as a target, and the authentication process may be performed.", "[0096] For an example shown in FIG. 15 , the printed portion of a retort-packed food is employed, and so long as a target can be read by a scanner, etc.", ", and an image for the target can be generated, the present invention can be applied for the target, regardless of which material and which printing method is employed for the target.", "[0097] For an example shown in FIG. 16 , the present invention is employed for the identification of a painting, and since the overall area of the target is printed matter, an arbitrary portion is available for the use of the present invention.", "Further, even for such a target that has been greatly deteriorated over time, since the connection points that match at a predetermined ratio are kept and are not lost, the authentication accuracy can be maintained.", "[0098] In the above examples, except for a tablet, a specific portion to be employed for authentication should be designated;", "however, such a portion can be designated by using a method well known in this technical field, for example, by determining the right end portion in advance, or by transmitting information about an area that has been selected." ]
BACKGROUND [0001] This invention relates generally to wireless devices such as peripherals for processor-based devices including personal computers, processor-based appliances, and game consoles. [0002] In a number of cases, a peripheral or input/output device may be conveniently carried with the user to operate a remote processor-based device. In such case, the user can position himself or herself where desired with greater freedom of movement relative to the controlled processor-based device. Thus, wireless keyboards and mice have become very popular. [0003] Generally, wireless peripherals are battery powered and operate under an appropriate protocol such as a radio frequency or infrared protocol. As long as the user is sufficiently close to a base station or the controlled processor-based device, the processor-based device and the peripheral may communicate, regardless of whether the user moves or not. [0004] Some peripheral devices such as consoles used to control game devices have generally not been amenable to such wireless links. Despite the fact that gaming situations may involve a plurality of users who may prefer to spread out in a room, wireless controls have not been widely adopted. Constant actuation of the gaming controls and the need for frequent and fast communications with the processor-based system that is being controlled means that the power dissipation of the remote control consoles is relatively high. Thus, batteries may have an extremely short life, necessitating constant changes and risking power failures in the middle of games. In addition, the weight involved in providing sufficient battery power to such consoles, may make those consoles somewhat unwieldy. [0005] Thus, there is a need for a better way to power wireless devices in relatively high power consumption applications. BRIEF DESCRIPTION OF THE DRAWINGS [0006] [0006]FIG. 1 is a perspective view of one embodiment of the present invention; [0007] [0007]FIG. 2 is a schematic depiction of one embodiment of the present invention; [0008] [0008]FIG. 3 is a front elevational view of the embodiment shown in FIG. 2 in a different position; and [0009] [0009]FIG. 4 is a schematic depiction of another embodiment of the present invention. DETAILED DESCRIPTION [0010] Referring to FIG. 1, a wireless device 10 may communicate with a remote processor-based system over an interface 12 . In one embodiment, the interface 12 may be an infrared interface that enables communications with the remote processor-based device using a suitable infrared protocol. Alternatively, the interface 12 may be a radio frequency interface which communicates with a similar interface associated with the processor-based device. [0011] In some embodiments, the wireless device 10 may be a game console that includes selection buttons 16 and a joystick 18 . A game console may be utilized to control a processor-based game that is being run on a remote processor-based system. [0012] In other embodiments, the wireless device 10 may be a mouse, a keyboard, or any of a variety of input/output devices for processor-based systems. All that is needed is that the wireless device 10 include controls that are actively operated. The selections that are made through the button 16 and joystick 18 are conveyed to the interface 12 for a transmission to the remote processor-based system (not shown). [0013] Referring to FIG. 2, the wireless device 10 may include an infrared signal transmitter 12 a in one embodiment. The transmitter 12 a receives signals from an in-console signal generating circuitry 36 . The circuitry 36 may be contained within the housing 14 of the device 10 in one embodiment. [0014] When the button 16 is depressed, it compresses a coil spring 22 in one embodiment. The shaft 17 of button 16 is pressed downwardly into the console 14 through an opening therein. Connected to the free end of the shaft 17 is a saw-tooth operator 24 . The saw-tooth operator 24 may be coupled to the shaft 17 via a pivoting connection 28 . The operator 24 is biased to the left in FIG. 2 by a coil spring 26 coupled to the housing 14 . Thus, the operator 24 includes teeth 25 that are biased into engagement with the teeth 27 of a gear wheel 30 . The gear wheel 30 may be coupled to a flywheel 22 in some embodiments. [0015] The downward operation of the button 16 results in downward movement of the shaft 17 and the operator 24 . The operator 24 is biased into engagement with the teeth 27 of the gear wheel 30 . Thus, the translation of the button 16 is converted into rotation in the direction of the arrow D of the gear wheel 30 . The rotation of the gear wheel 30 results in rotation of the link 33 around its axis. [0016] A flywheel 32 may be mounted on the gear wheel 30 to increase the energy storage capability of the gear wheel 30 . The rotation of the link 33 about its axis results in rotational motion that is converted into electricity by the generator 34 . [0017] The potential generated by the generator 34 is supplied across the terminals of a storage capacitor 42 . The storage capacitor 42 may then power the in-console generating circuitry 36 . The wireless device 10 may produce sufficient power to generate signals for transmission to the remote processor-based device and to operate displays that may reside on the wireless device 10 . In some embodiments, depending on the frequency of button 16 operation, an additional battery 40 may be provided as well. [0018] Movement of the button 16 may be detected by a sensor 38 which is also conveyed to the circuitry 36 . The signals developed by the circuitry 36 may be passed through the infrared signal transmitter 12 a in one embodiment. In other embodiments, transmitters other than infrared signal transmitters may be utilized as described previously. [0019] When the button 16 is released, it springs upwardly in the direction of arrow C shown in FIG. 3. That is, the coil spring 22 attempts to return to its initial position by biasing the button 16 upwardly. The upward movement of the button 16 lifts the shaft 17 and operator 24 . The upward movement biases the operator 24 against the tension supplied by the coil spring 26 because of the saw-tooth shape of the teeth 25 . In particular, the surface 29 of each tooth 25 is biased by the teeth 27 so that the operator 24 is pushed to the right in FIG. 3. Thus, the operator 24 disengages from the gear wheel 30 preventing reverse rotation thereof. In some cases, the gear wheel 30 may continue to spin, for example, under the influence of the flywheel 32 , as indicated by the arrow D. [0020] Thus, the repeated actuation of control button 16 on the housing 14 may be converted into potential. The generated potential may be utilized to power the wireless device 10 either without batteries or in conjunction with batteries. [0021] In some embodiments, other control devices may also be equipped with power conversion devices. For example, the joystick 18 may be coupled to a shaft 50 that is mounted on a ball and socket joint 52 . Thus, the joystick 18 may be rotated relative to the ball and socket joint 52 . Rotation of the shaft 50 may be detected by a sensor 54 and provided to the in-console generating circuit 36 . In one embodiment, the circuitry 36 may be coupled to a transmitter 12 a. [0022] Rotation of the joystick 18 in the direction of the arrow E in FIG. 4 translates the operator 24 to the right causing the teeth 25 to rotate the gear wheel 30 having teeth 27 . Thus, the gear wheel 30 is rotated in the direction indicated by the arrow F causing rotation of the link 33 . Again, the rotation of the link 33 powers a generator 34 which produces a charge across the storage capacitor 42 . This charge then operates as a power source for the circuitry 36 . [0023] When the joystick 38 is operated in a direction opposite the direction E, the operator 24 disengages from the gear wheel 30 in one embodiment. In some cases, additional operators 24 may be utilized to capture the available energy in all directions of displacement of the joystick 18 . [0024] While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.
A wireless peripheral for a processor-based device may include a plurality of operators or control buttons that are operated to indicate commands. Those commands may be forwarded over a wireless link in the form of electrical signals to the processor-based device. Operation of the controls or operators may be converted into electrical energy which may be utilized to power the wireless peripheral.
Briefly describe the main invention outlined in the provided context.
[ "BACKGROUND [0001] This invention relates generally to wireless devices such as peripherals for processor-based devices including personal computers, processor-based appliances, and game consoles.", "[0002] In a number of cases, a peripheral or input/output device may be conveniently carried with the user to operate a remote processor-based device.", "In such case, the user can position himself or herself where desired with greater freedom of movement relative to the controlled processor-based device.", "Thus, wireless keyboards and mice have become very popular.", "[0003] Generally, wireless peripherals are battery powered and operate under an appropriate protocol such as a radio frequency or infrared protocol.", "As long as the user is sufficiently close to a base station or the controlled processor-based device, the processor-based device and the peripheral may communicate, regardless of whether the user moves or not.", "[0004] Some peripheral devices such as consoles used to control game devices have generally not been amenable to such wireless links.", "Despite the fact that gaming situations may involve a plurality of users who may prefer to spread out in a room, wireless controls have not been widely adopted.", "Constant actuation of the gaming controls and the need for frequent and fast communications with the processor-based system that is being controlled means that the power dissipation of the remote control consoles is relatively high.", "Thus, batteries may have an extremely short life, necessitating constant changes and risking power failures in the middle of games.", "In addition, the weight involved in providing sufficient battery power to such consoles, may make those consoles somewhat unwieldy.", "[0005] Thus, there is a need for a better way to power wireless devices in relatively high power consumption applications.", "BRIEF DESCRIPTION OF THE DRAWINGS [0006] [0006 ]FIG. 1 is a perspective view of one embodiment of the present invention;", "[0007] [0007 ]FIG. 2 is a schematic depiction of one embodiment of the present invention;", "[0008] [0008 ]FIG. 3 is a front elevational view of the embodiment shown in FIG. 2 in a different position;", "and [0009] [0009 ]FIG. 4 is a schematic depiction of another embodiment of the present invention.", "DETAILED DESCRIPTION [0010] Referring to FIG. 1, a wireless device 10 may communicate with a remote processor-based system over an interface 12 .", "In one embodiment, the interface 12 may be an infrared interface that enables communications with the remote processor-based device using a suitable infrared protocol.", "Alternatively, the interface 12 may be a radio frequency interface which communicates with a similar interface associated with the processor-based device.", "[0011] In some embodiments, the wireless device 10 may be a game console that includes selection buttons 16 and a joystick 18 .", "A game console may be utilized to control a processor-based game that is being run on a remote processor-based system.", "[0012] In other embodiments, the wireless device 10 may be a mouse, a keyboard, or any of a variety of input/output devices for processor-based systems.", "All that is needed is that the wireless device 10 include controls that are actively operated.", "The selections that are made through the button 16 and joystick 18 are conveyed to the interface 12 for a transmission to the remote processor-based system (not shown).", "[0013] Referring to FIG. 2, the wireless device 10 may include an infrared signal transmitter 12 a in one embodiment.", "The transmitter 12 a receives signals from an in-console signal generating circuitry 36 .", "The circuitry 36 may be contained within the housing 14 of the device 10 in one embodiment.", "[0014] When the button 16 is depressed, it compresses a coil spring 22 in one embodiment.", "The shaft 17 of button 16 is pressed downwardly into the console 14 through an opening therein.", "Connected to the free end of the shaft 17 is a saw-tooth operator 24 .", "The saw-tooth operator 24 may be coupled to the shaft 17 via a pivoting connection 28 .", "The operator 24 is biased to the left in FIG. 2 by a coil spring 26 coupled to the housing 14 .", "Thus, the operator 24 includes teeth 25 that are biased into engagement with the teeth 27 of a gear wheel 30 .", "The gear wheel 30 may be coupled to a flywheel 22 in some embodiments.", "[0015] The downward operation of the button 16 results in downward movement of the shaft 17 and the operator 24 .", "The operator 24 is biased into engagement with the teeth 27 of the gear wheel 30 .", "Thus, the translation of the button 16 is converted into rotation in the direction of the arrow D of the gear wheel 30 .", "The rotation of the gear wheel 30 results in rotation of the link 33 around its axis.", "[0016] A flywheel 32 may be mounted on the gear wheel 30 to increase the energy storage capability of the gear wheel 30 .", "The rotation of the link 33 about its axis results in rotational motion that is converted into electricity by the generator 34 .", "[0017] The potential generated by the generator 34 is supplied across the terminals of a storage capacitor 42 .", "The storage capacitor 42 may then power the in-console generating circuitry 36 .", "The wireless device 10 may produce sufficient power to generate signals for transmission to the remote processor-based device and to operate displays that may reside on the wireless device 10 .", "In some embodiments, depending on the frequency of button 16 operation, an additional battery 40 may be provided as well.", "[0018] Movement of the button 16 may be detected by a sensor 38 which is also conveyed to the circuitry 36 .", "The signals developed by the circuitry 36 may be passed through the infrared signal transmitter 12 a in one embodiment.", "In other embodiments, transmitters other than infrared signal transmitters may be utilized as described previously.", "[0019] When the button 16 is released, it springs upwardly in the direction of arrow C shown in FIG. 3. That is, the coil spring 22 attempts to return to its initial position by biasing the button 16 upwardly.", "The upward movement of the button 16 lifts the shaft 17 and operator 24 .", "The upward movement biases the operator 24 against the tension supplied by the coil spring 26 because of the saw-tooth shape of the teeth 25 .", "In particular, the surface 29 of each tooth 25 is biased by the teeth 27 so that the operator 24 is pushed to the right in FIG. 3. Thus, the operator 24 disengages from the gear wheel 30 preventing reverse rotation thereof.", "In some cases, the gear wheel 30 may continue to spin, for example, under the influence of the flywheel 32 , as indicated by the arrow D. [0020] Thus, the repeated actuation of control button 16 on the housing 14 may be converted into potential.", "The generated potential may be utilized to power the wireless device 10 either without batteries or in conjunction with batteries.", "[0021] In some embodiments, other control devices may also be equipped with power conversion devices.", "For example, the joystick 18 may be coupled to a shaft 50 that is mounted on a ball and socket joint 52 .", "Thus, the joystick 18 may be rotated relative to the ball and socket joint 52 .", "Rotation of the shaft 50 may be detected by a sensor 54 and provided to the in-console generating circuit 36 .", "In one embodiment, the circuitry 36 may be coupled to a transmitter 12 a. [0022] Rotation of the joystick 18 in the direction of the arrow E in FIG. 4 translates the operator 24 to the right causing the teeth 25 to rotate the gear wheel 30 having teeth 27 .", "Thus, the gear wheel 30 is rotated in the direction indicated by the arrow F causing rotation of the link 33 .", "Again, the rotation of the link 33 powers a generator 34 which produces a charge across the storage capacitor 42 .", "This charge then operates as a power source for the circuitry 36 .", "[0023] When the joystick 38 is operated in a direction opposite the direction E, the operator 24 disengages from the gear wheel 30 in one embodiment.", "In some cases, additional operators 24 may be utilized to capture the available energy in all directions of displacement of the joystick 18 .", "[0024] While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom.", "It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention." ]
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to pneumatic tires. In particular it relates to an improvement in shape of a main circumferential groove in a pneumatic tire for use in vehicles such as trucks, buses, and the like, that run on both paved roads and gravel roads. 2. Description of the Prior Art Generally, a main groove in a tread of a pneumatic tire for use in vehicles such as trucks, buses, and the like, is made deep to prolong the wear life of the tire. The width of the main groove is restricted to be less than a predetermined limit to provide sufficient rubber to be worn during the life of the tire. Therefore, there is a problem in the sectional shape of the main groove since the groove depth is deep and the groove angle is small for the groove width. Such a groove is apt to seize and retain stones. The larger the ratio of the groove width W to the depth H (W/H), the possibility of stone seizing by the groove is decreased. However, if the groove depth is made deeper with ratio W/H kept constant, the groove width becomes wide, so that the amount of rubber to be worn out is decreased thus reducing the lifetime of the tire. Accordingly, the ratio W/H of groove width to the depth is in prior art tires generally selected to be about 0.5 -0.8. Conventionally, as illustrated in FIGS. 2 and 3 for example, a pneumatic tire 6 has a main groove 1 having a substantially U-shaped section and circumferentially formed in an outer surface region 2a of a tread 2. Each of the opposite side wall surfaces 3 of the main groove 1 is slanted to form an angle α 1 of, for example, 13 degrees with a normal line 5 perpendicular to an outer surface 2b of the tread 2. However, when the pneumatic tire 6 having such a main groove 1 is driven on a road 7 where pieces of stone 9 are scattered, the opening of the groove 1 is widened at a side 8a of the tire 6 (FIG.. 3) to seize the stone 9. The stone 9 once seized in the main groove 1 is pushed further into the main groove 1 at a portion just below portion of a load 8b. It is thus urged into the main groove 1 between the wall surfaces 3 thereof, so that even after the main groove 1 rotates away from a road surface 7, a large retaining force F 1 is exerted onto the stone 9 at the outer surface 2b of the tread 2. This is illustrated in FIG. 4. The force F 1 prevents the stone 9 from being discharged from the main groove 1. FIG. 5, illustrated another pneumatic tire provided with a main groove 11 in which each of the opposite side walls of the groove 11 are inclined at compound angles in an opening portion 11a of the groove 11. Two side wall angles α 1 and α 2 formed between a side groove wall surface 12 at the opening portion 11a and a normal line 5. The angle α 2 is about 25 degrees. In such a main groove 11 having such an opening portion 11a, the groove 11 does not readily seize a stone because of the enlarged opening of the groove. However, when a stone is pushed into an inner portion of the groove from the opening, the stone is pushed farther into the inner portion of the main groove 11. The stone cannot be discharged from the groove because a fastening force is exerted onto the stone from the wall surfaces as in the case of the main groove 1 of the conventional tire as described with reference to FIGS. 2-4. There is therefore a problem that if the groove is formed with the groove wall angle at the opening portion 11a as illustrated, the groove depth becomes so shallow that the life of the tire is reduced. That is, there is an inverse relationship between the groove depth and the stone-seizing characteristic of the groove. Also, as the tire wears, when the tread gauge 22 is reduced, the groove depth decreased eliminating walls 12 and angle α 2 . The groove 3 is then identical to FIG. 2. BRIEF SUMMARY OF THE INVENTION An object of the present invention is therefore to eliminate drawbacks in the prior art pneumatic tires. Another object of the present invention is to provide a pneumatic tire in which the depth of the main groove is deep to prolong the life of the tire yet having the main groove with a shape to reduce the tendency for stone-seizing. To attain the above objects, according to one aspect of the present invention, the pneumatic tire has at least one main wide groove substantially circumferentially extending in a tread of the tire and having opposite side walls, at least one of the side walls being composed of an outer region located at a radially outer portion of the one side wall, an inner region located at a radially inner portion of the one side wall, and an intermediate region located between the inner and outer regions, groove wall angles formed between a normal line perpendicular to an outer surface of the tread and respective surface portions of the one side wall in the outer and inner regions are selected to be larger than a groove wall angle formed between the normal line and a surface portion of the one side wall in the intermediate region. Preferably, each of the respective groove wall angles in the inner and outer regions of the main groove is selected within a range of 20 to 40 degrees. The reason why the groove angle in the outer region is selected within such a range is as follows. When the angle is selected to be smaller than 20 degrees, the groove is apt to seize a piece of stone, conversely, when the angle is selected to be larger than 40 degrees, an effective shape of the main groove cannot be obtained but also the groove wall angle in the inner region of the groove becomes small if the groove width is limited. A stone is then apt to be urged farther into the inner portion of the groove. Preferably, the groove wall angle in the inner region of the main groove is selected to be larger than that in the outer region. This is because the inner region having a larger groove wall angle acts to prevent a stone from being urged farther into the groove and to discharge a stone pushed into the inner region. Further, preferably, the intermediate region of the side wall of the main groove includes a central zone of the groove depth, with the height of the intermediate region within a range of from 15 to 35% of the entire groove depth. The groove wall angle in the intermediate region of the side wall of the main groove is selected to be within a range of from 0 to 10 degrees, preferably from 0 to 5 degrees. It is important to provide the intermediate region as a portion of the groove. This is because the intermediate region makes it possible to have the groove wall angle in the outer region large so that the groove will not grab stones and also to make the groove wall angle in the inner region large. Preferably, the groove wall angle in the inner, region is selected to be larger than that in the outer region, to effectively prevent stones from cutting into the rubber in the groove bottom. That is, the above-mentioned conflicting design constraints can be solved simultaneously by this invention. In the pneumatic tire according to the present invention, since at least one of opposite side walls of the circumferentially formed groove is composed of the outer region, the intermediate region, and the inner region, in this order in the direction from the radial outer surface of the tire, and because of the provision of the intermediate region formed in radially intermediate portion of the groove, it is possible to make large the angles of the respective side walls in the outer and inner regions independent of each other to prevent stones from being seized and to make the length of the intermediate range longer to secure the entire depth of the groove. Furthermore, since the angle formed between the normal line perpendicular to the tread surface and each of the side wall surface portions in the outer and inner regions is larger than the angle formed between the normal line and the side wall surface portion in the intermediate region, the tire will not seize stones even when the tire is driven on a road. Accordingly, in the pneumatic tire according to the present invention, the main groove can be made deeper with the groove width maintained at a predetermined value while preventing stones from being grabbed by the 2nd and retained in the groove. BRIEF DESCRIPTION OF THE DRAWINGS FIG.1 is a sectional view illustrating a main groove portion of an embodiment of the pneumatic tire according to the present invention; FIG.2 is a sectional view illustrating a main groove portion of a conventional pneumatic tire; FIG.3 is a side view explaining the state of stone-seizing in the conventional pneumatic tire of FIG.2; FIG. 4 is a section showing the main portion similar to FIG. 2 for explaining the state of stone-seizing; and FIG. 5 is a section showing a main portion of another conventional pneumatic tire. DESCRIPTION OF PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described hereunder with reference to the drawings. FIG.1 illustrates an embodiment of the pneumatic tire according to the present invention. A main groove 21 is circumferentially provided in an outer surface 23a of a tread 23 of a tire 22. For purposes of illustration, the tire can be a steel belted radial tire, the size thereof 11R22.5. A side wall 21a, one of the side walls of the main groove 21, is composed of an outer wall 25 located at a radially outer portion, an inner wall 26 located at a radially inner portion, and an intermediate wall 27 located between the inner wall 26 and the outer wall 25. In the main groove 21, the depth H 21 and width W 21 are selected to be 23 mm and 16 mm respectively, and the heights h 25 , h 26 and h 27 , in the radial direction, of the outer, inner and intermediate regions are selected to be 8 mm, 8 mm and 7 mm respectively. These dimensions are preferred for the 11R22.5 tire. The ratio of width to depth may be in the range of 0.5-0.8. The intermediate region is provided to cross a substantially central position of the groove depth H 21 , that is, a position having a height h 28 in radial direction which is selected to be 11.5 mm from a surface 23b of the tread 23 (i.e. H 28 =0.5H 21 ). Let α 25 , and α 26 , and α 27 be the respective groove wall angles between the line N perpendicular to the surface 23b of the tread 23 and respective side wall surfaces 25, 26, and 27 of the outer, inner, and intermediate regions. The groove wall angles α 25 , α 26 and α 27 are selected to be 32 degrees, 37 degrees and 3 degrees respectively. Thus, each of the respective groove wall angles α 25 , α 26 of the outer and inner walls 25 and 26 is larger than the groove wall angle α 27 of the intermediate wall 27, and falls within the range of from 20 to 40 degrees. Further, the groove wall angle α 26 of the inner wall 26 (37 degrees) is larger than the groove wall angle α 25 of the outer wall 25 (32 degrees). Furthermore, the groove wall angle α 29 between the normal line N and a wall surface 29 of the other side wall 2lb of main groove 21 is selected to be 5 degrees. Thus the angle α 27 is substantially equal to α 29 . The pneumatic tire of this embodiment has the same structure as that of conventional pneumatic steel radial tires with the exception of the main groove illustrated in FIG.1 and described herein. The description of the remaining portions of the tire is omitted. Next, the operation of the main groove will be described. In the pneumatic tire according to the present invention, the main groove 21 has three regions defined by the side walls, that is, the outer region, the inner region, and the intermediate region. Since the groove wall angle α 27 of the intermediate wall 27 is so small that the side wall surface 27 is substantially parallel to the normal line N, it is possible to make the groove wall angles of the outer and inner regions as well as the groove depth large without increasing the groove width and without lowering the wear characteristics of the tire. Further, even when the pneumatic tire according to the present invention runs on a stony road, the tire will not seize stones at the tread side of the tire because the groove wall angle α 25 of the outer region of the main groove 21 is sufficiently larger (32 degrees). Furthermore, even where a stone is seized by and pushed into the groove, the stone does not cut into the tread rubber to cause a fault. Rather it is discharged out of the groove because the groove wall angle α 26 (37 degrees ) of the inner region 26 is selected to be larger than the groove wall angle α 25 (32 degrees) of the outer region 25. To confirm the superiority of operation of a tire using a groove in accordance with the invention, two kinds of test tires (tubeless, size 11R22.5) for a test of the embodiment and for a comparative example. The test tire for the embodiment was that shown in FIG. 1 and the test tire as the comparative example was the conventional one shown in FIG.2, each tire having the groove depth of 23 mm, the groove width of 16 mm, and the groove wall angle α 1 of 13 degrees. But the main groove construction, the tires were the same. The test was performed in such a manner that the test tires were attached on a drive shaft of a semitrailer and the semitrailer was driven on an ordinary road (80% of a paved road and 20% of a gravel road). The numbers of stones seized by the grooves of the test tires were examined after 50,000 kilometers running (30% of wearing-out ratio of the tread) and after 150,000kilometers running (85% of wearing-out ratio of the tread). In the test after 50,000 kilometer-running, 60 pieces of stone seized in the groove were detected in the comparative example (conventional tire), while only 5 pieces of stone were detected in the tire of this embodiment. In the test after 150,000 kilometers running, 41 pieces of stone were seized in the groove in the comparative example (conventional tire) and 15 pieces of them caused such a fault that they cut into the tread rubber at the groove bottom to reach a belt layer. In contrast, only three pieces of stone were seized in the groove of the test tire of the embodiment without causing any fault. As described above, in the tire according to the present invention, the lifetime thereof can be prolonged with the groove thereof made deeper, and the amount of stone-seizing by the groove can be significantly reduced so that tread peeling-off faults caused by stone-seizing can be prevented.
A main circumferential groove for a pneumatic tire having asymmetrical side walls. One of the side walls has three segments each inclined differently to a line normal to the tread surface. The angle of the inner segment is larger than that of an outer segment.
Provide a concise summary of the essential information conveyed in the given context.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention This invention relates to pneumatic tires.", "In particular it relates to an improvement in shape of a main circumferential groove in a pneumatic tire for use in vehicles such as trucks, buses, and the like, that run on both paved roads and gravel roads.", "Description of the Prior Art Generally, a main groove in a tread of a pneumatic tire for use in vehicles such as trucks, buses, and the like, is made deep to prolong the wear life of the tire.", "The width of the main groove is restricted to be less than a predetermined limit to provide sufficient rubber to be worn during the life of the tire.", "Therefore, there is a problem in the sectional shape of the main groove since the groove depth is deep and the groove angle is small for the groove width.", "Such a groove is apt to seize and retain stones.", "The larger the ratio of the groove width W to the depth H (W/H), the possibility of stone seizing by the groove is decreased.", "However, if the groove depth is made deeper with ratio W/H kept constant, the groove width becomes wide, so that the amount of rubber to be worn out is decreased thus reducing the lifetime of the tire.", "Accordingly, the ratio W/H of groove width to the depth is in prior art tires generally selected to be about 0.5 -0.8.", "Conventionally, as illustrated in FIGS. 2 and 3 for example, a pneumatic tire 6 has a main groove 1 having a substantially U-shaped section and circumferentially formed in an outer surface region 2a of a tread 2.", "Each of the opposite side wall surfaces 3 of the main groove 1 is slanted to form an angle α 1 of, for example, 13 degrees with a normal line 5 perpendicular to an outer surface 2b of the tread 2.", "However, when the pneumatic tire 6 having such a main groove 1 is driven on a road 7 where pieces of stone 9 are scattered, the opening of the groove 1 is widened at a side 8a of the tire 6 (FIG..", "3) to seize the stone 9.", "The stone 9 once seized in the main groove 1 is pushed further into the main groove 1 at a portion just below portion of a load 8b.", "It is thus urged into the main groove 1 between the wall surfaces 3 thereof, so that even after the main groove 1 rotates away from a road surface 7, a large retaining force F 1 is exerted onto the stone 9 at the outer surface 2b of the tread 2.", "This is illustrated in FIG. 4. The force F 1 prevents the stone 9 from being discharged from the main groove 1.", "FIG. 5, illustrated another pneumatic tire provided with a main groove 11 in which each of the opposite side walls of the groove 11 are inclined at compound angles in an opening portion 11a of the groove 11.", "Two side wall angles α 1 and α 2 formed between a side groove wall surface 12 at the opening portion 11a and a normal line 5.", "The angle α 2 is about 25 degrees.", "In such a main groove 11 having such an opening portion 11a, the groove 11 does not readily seize a stone because of the enlarged opening of the groove.", "However, when a stone is pushed into an inner portion of the groove from the opening, the stone is pushed farther into the inner portion of the main groove 11.", "The stone cannot be discharged from the groove because a fastening force is exerted onto the stone from the wall surfaces as in the case of the main groove 1 of the conventional tire as described with reference to FIGS. 2-4.", "There is therefore a problem that if the groove is formed with the groove wall angle at the opening portion 11a as illustrated, the groove depth becomes so shallow that the life of the tire is reduced.", "That is, there is an inverse relationship between the groove depth and the stone-seizing characteristic of the groove.", "Also, as the tire wears, when the tread gauge 22 is reduced, the groove depth decreased eliminating walls 12 and angle α 2 .", "The groove 3 is then identical to FIG. 2. BRIEF SUMMARY OF THE INVENTION An object of the present invention is therefore to eliminate drawbacks in the prior art pneumatic tires.", "Another object of the present invention is to provide a pneumatic tire in which the depth of the main groove is deep to prolong the life of the tire yet having the main groove with a shape to reduce the tendency for stone-seizing.", "To attain the above objects, according to one aspect of the present invention, the pneumatic tire has at least one main wide groove substantially circumferentially extending in a tread of the tire and having opposite side walls, at least one of the side walls being composed of an outer region located at a radially outer portion of the one side wall, an inner region located at a radially inner portion of the one side wall, and an intermediate region located between the inner and outer regions, groove wall angles formed between a normal line perpendicular to an outer surface of the tread and respective surface portions of the one side wall in the outer and inner regions are selected to be larger than a groove wall angle formed between the normal line and a surface portion of the one side wall in the intermediate region.", "Preferably, each of the respective groove wall angles in the inner and outer regions of the main groove is selected within a range of 20 to 40 degrees.", "The reason why the groove angle in the outer region is selected within such a range is as follows.", "When the angle is selected to be smaller than 20 degrees, the groove is apt to seize a piece of stone, conversely, when the angle is selected to be larger than 40 degrees, an effective shape of the main groove cannot be obtained but also the groove wall angle in the inner region of the groove becomes small if the groove width is limited.", "A stone is then apt to be urged farther into the inner portion of the groove.", "Preferably, the groove wall angle in the inner region of the main groove is selected to be larger than that in the outer region.", "This is because the inner region having a larger groove wall angle acts to prevent a stone from being urged farther into the groove and to discharge a stone pushed into the inner region.", "Further, preferably, the intermediate region of the side wall of the main groove includes a central zone of the groove depth, with the height of the intermediate region within a range of from 15 to 35% of the entire groove depth.", "The groove wall angle in the intermediate region of the side wall of the main groove is selected to be within a range of from 0 to 10 degrees, preferably from 0 to 5 degrees.", "It is important to provide the intermediate region as a portion of the groove.", "This is because the intermediate region makes it possible to have the groove wall angle in the outer region large so that the groove will not grab stones and also to make the groove wall angle in the inner region large.", "Preferably, the groove wall angle in the inner, region is selected to be larger than that in the outer region, to effectively prevent stones from cutting into the rubber in the groove bottom.", "That is, the above-mentioned conflicting design constraints can be solved simultaneously by this invention.", "In the pneumatic tire according to the present invention, since at least one of opposite side walls of the circumferentially formed groove is composed of the outer region, the intermediate region, and the inner region, in this order in the direction from the radial outer surface of the tire, and because of the provision of the intermediate region formed in radially intermediate portion of the groove, it is possible to make large the angles of the respective side walls in the outer and inner regions independent of each other to prevent stones from being seized and to make the length of the intermediate range longer to secure the entire depth of the groove.", "Furthermore, since the angle formed between the normal line perpendicular to the tread surface and each of the side wall surface portions in the outer and inner regions is larger than the angle formed between the normal line and the side wall surface portion in the intermediate region, the tire will not seize stones even when the tire is driven on a road.", "Accordingly, in the pneumatic tire according to the present invention, the main groove can be made deeper with the groove width maintained at a predetermined value while preventing stones from being grabbed by the 2nd and retained in the groove.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG[.", "].1 is a sectional view illustrating a main groove portion of an embodiment of the pneumatic tire according to the present invention;", "FIG[.", "].2 is a sectional view illustrating a main groove portion of a conventional pneumatic tire;", "FIG[.", "].3 is a side view explaining the state of stone-seizing in the conventional pneumatic tire of FIG[.", "].2;", "FIG. 4 is a section showing the main portion similar to FIG. 2 for explaining the state of stone-seizing;", "and FIG. 5 is a section showing a main portion of another conventional pneumatic tire.", "DESCRIPTION OF PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described hereunder with reference to the drawings.", "FIG[.", "].1 illustrates an embodiment of the pneumatic tire according to the present invention.", "A main groove 21 is circumferentially provided in an outer surface 23a of a tread 23 of a tire 22.", "For purposes of illustration, the tire can be a steel belted radial tire, the size thereof 11R22.5.", "A side wall 21a, one of the side walls of the main groove 21, is composed of an outer wall 25 located at a radially outer portion, an inner wall 26 located at a radially inner portion, and an intermediate wall 27 located between the inner wall 26 and the outer wall 25.", "In the main groove 21, the depth H 21 and width W 21 are selected to be 23 mm and 16 mm respectively, and the heights h 25 , h 26 and h 27 , in the radial direction, of the outer, inner and intermediate regions are selected to be 8 mm, 8 mm and 7 mm respectively.", "These dimensions are preferred for the 11R22.5 tire.", "The ratio of width to depth may be in the range of 0.5-0.8.", "The intermediate region is provided to cross a substantially central position of the groove depth H 21 , that is, a position having a height h 28 in radial direction which is selected to be 11.5 mm from a surface 23b of the tread 23 (i.e. H 28 =0.5H 21 ).", "Let α 25 , and α 26 , and α 27 be the respective groove wall angles between the line N perpendicular to the surface 23b of the tread 23 and respective side wall surfaces 25, 26, and 27 of the outer, inner, and intermediate regions.", "The groove wall angles α 25 , α 26 and α 27 are selected to be 32 degrees, 37 degrees and 3 degrees respectively.", "Thus, each of the respective groove wall angles α 25 , α 26 of the outer and inner walls 25 and 26 is larger than the groove wall angle α 27 of the intermediate wall 27, and falls within the range of from 20 to 40 degrees.", "Further, the groove wall angle α 26 of the inner wall 26 (37 degrees) is larger than the groove wall angle α 25 of the outer wall 25 (32 degrees).", "Furthermore, the groove wall angle α 29 between the normal line N and a wall surface 29 of the other side wall 2lb of main groove 21 is selected to be 5 degrees.", "Thus the angle α 27 is substantially equal to α 29 .", "The pneumatic tire of this embodiment has the same structure as that of conventional pneumatic steel radial tires with the exception of the main groove illustrated in FIG[.", "].1 and described herein.", "The description of the remaining portions of the tire is omitted.", "Next, the operation of the main groove will be described.", "In the pneumatic tire according to the present invention, the main groove 21 has three regions defined by the side walls, that is, the outer region, the inner region, and the intermediate region.", "Since the groove wall angle α 27 of the intermediate wall 27 is so small that the side wall surface 27 is substantially parallel to the normal line N, it is possible to make the groove wall angles of the outer and inner regions as well as the groove depth large without increasing the groove width and without lowering the wear characteristics of the tire.", "Further, even when the pneumatic tire according to the present invention runs on a stony road, the tire will not seize stones at the tread side of the tire because the groove wall angle α 25 of the outer region of the main groove 21 is sufficiently larger (32 degrees).", "Furthermore, even where a stone is seized by and pushed into the groove, the stone does not cut into the tread rubber to cause a fault.", "Rather it is discharged out of the groove because the groove wall angle α 26 (37 degrees ) of the inner region 26 is selected to be larger than the groove wall angle α 25 (32 degrees) of the outer region 25.", "To confirm the superiority of operation of a tire using a groove in accordance with the invention, two kinds of test tires (tubeless, size 11R22.5) for a test of the embodiment and for a comparative example.", "The test tire for the embodiment was that shown in FIG. 1 and the test tire as the comparative example was the conventional one shown in FIG[.", "].2, each tire having the groove depth of 23 mm, the groove width of 16 mm, and the groove wall angle α 1 of 13 degrees.", "But the main groove construction, the tires were the same.", "The test was performed in such a manner that the test tires were attached on a drive shaft of a semitrailer and the semitrailer was driven on an ordinary road (80% of a paved road and 20% of a gravel road).", "The numbers of stones seized by the grooves of the test tires were examined after 50,000 kilometers running (30% of wearing-out ratio of the tread) and after 150,000kilometers running (85% of wearing-out ratio of the tread).", "In the test after 50,000 kilometer-running, 60 pieces of stone seized in the groove were detected in the comparative example (conventional tire), while only 5 pieces of stone were detected in the tire of this embodiment.", "In the test after 150,000 kilometers running, 41 pieces of stone were seized in the groove in the comparative example (conventional tire) and 15 pieces of them caused such a fault that they cut into the tread rubber at the groove bottom to reach a belt layer.", "In contrast, only three pieces of stone were seized in the groove of the test tire of the embodiment without causing any fault.", "As described above, in the tire according to the present invention, the lifetime thereof can be prolonged with the groove thereof made deeper, and the amount of stone-seizing by the groove can be significantly reduced so that tread peeling-off faults caused by stone-seizing can be prevented." ]
BACKGROUND ART 1. Technical Field The subject invention relates to cord and rope holders. More particularly, the subject invention relates to a pivoting halyard retainer. 2. Description of Related Art Flagstaffs and masts are used to support articles, typically made of fabric, high above the reach of man. The flagstaffs and masts, hereinafter referred to as flagstaffs, are thin pole-shaped structures used as unobtrusive structures to support these articles, such as flags, sails, pennants, and the like. The standard method of hoisting the flag or sail is stringing a rope, or halyard, up through an eye hook at the top of the flagstaff and back down to the ground attaching the flag to the halyard. The halyard is secured at the bottom of the flagstaff via a cleat. The flag is lifted by pulling one half of the halyard down thus pulling the other end of the halyard up through the eye hook. The flag is then lifted up to the top of the flagstaff. When the flag is to be removed, the opposite end of the halyard is pulled. A problem arises when a wind is present. Noise is produced between the halyard and the flagstaff when the halyard collides with the flagstaff because of it flapping in the wind. This problem becomes particularly bothersome at night because the noise keeps everyone in the vicinity awake. Outside of releasing the halyard to flap freely in the wind presumably away from the flagstaff, which is not a very satisfying solution, for sailors in particular, there is no known remedy. U.S. Pat. No. 4,313,391 to Hall issued Feb. 2, 1982, discloses a mast shroud system for spreading support the shrouds of a mast to aid in the attachment and removal of the shrouds to and from the mast. Although this system effectively moves the shrouds away from the mast, thus reducing the amount of noise created by the shroud hitting the mast, this system does not contemplate the separation of the halyards from the mast. The shroud system is not capable of handling halyards which must be used, raised and lowered, on a regular basis. The nature of the shrouds are to support the mast and will not be frequently removed. In addition, the mast shroud system must always be used and, therefore, has no need nor even capability to be stored in an unobtrusive position. U.S. Pat. No. 876,770 to Brundell, issued Jan. 14, 1908, discloses a rope holding device for securing a rope used to open and close curtains. The rope holding device comprises an arm with a notch extending from the interior of the arm out to the periphery of the arm in a direction perpendicular to the longitudinal axis of the arm. The device further includes a spring loaded sleeve which is forced by the spring out over the notch in the arm. Therefore, when the rope is inserted into the notch, the sleeve clamps the rope in place not allowing it to move. Additionally, a support arm is attached to the arm via the sleeve to prevent the arm from rotating due to a force which may be applied to the arm by the clamped rope. A stop prevents the arm and support arm from collapsing against the wall when not in use by restricting the amount of clockwise rotation. This system is inadequate for reducing the amount of noise created by the halyard hitting the flagstaff because a lateral wind is capable of overcoming the lateral force created by the longitudinal force of the spring loaded sleeve. The rope will be subsequently forced out of the holder. The rope holding device is designed for indoor use and is not designed to withstand the forces that it may encounter in an outdoor environment having gusting winds and storms. The rope would be freed from its holder and begin to flap in the wind and, invariably, create the irritating noise of the halyard hitting the flagstaff. SUMMARY OF THE INVENTION AND ADVANTAGES A halyard retaining assembly for eliminating noise produced by a halyard colliding with a pole structure comprises arm means. The arm means has a base end and a distal end defining a longitudinal axis therebetween for extending the halyard away from the pole structure. The base means is fixedly securable to the pole structure for supporting the arm means at the base end. Halyard restricting means is disposed adjacent the distal end of the arm means for removably securing the halyard at the distal end of the arm means. Rotating means supports the arm means on the base end for rotating the arm means about the base end relative to the base means. The assembly is characterized by the halyard restricting means including at least one slot having a portion extending substantially parallel to the longitudinal axis. The assembly eliminates the method of releasing the halyards to fly in the wind by retaining the halyard out and away from the flagstaff thus eliminating any noise which may be produced by the halyard coming into contact with the flagstaff. An added advantage of the subject invention is that it can be rotated to a stored position so it will be visually less obtrusive when it is not as important that the halyards are hitting the flagstaff. BRIEF DESCRIPTION OF THE DRAWINGS Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: FIG. 1 is a side view of the preferred embodiment of the subject invention; FIG. 2 is an exploded perspective view of the preferred embodiment cf the subject invention; FIG. 3 is a fragmentary plan view of a first alternative embodiment of the subject invention; and FIG. 4 is a fragmentary plan view of a second alternative embodiment of the subject invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, wherein like numerals indicate like or corresponding parts throughout the several views, the subject invention is a flagstaff attached halyard retainer and is generally shown at 10. The subject invention 10 eliminates the irritating noise created by a halyard 12 hitting a pole structure 14, such as a flagstaff or a mast, due to any wind which may be present. For simplicity, the pole structure 14 will hereinafter be referred to as a flagstaff 14. The subject invention 10 includes arm means, generally indicated at 18. The arm means 16 has a base end 18 and a distal end 20 with a body 22 extending therebetween defining a longitudinal axis A. The arm means 16 extends the halyard 12 out and away from the flagstaff 14. The arm means 16 does not increase the tension in the halyard 12; it moves the halyard 12 away from the flagstaff 14 a distance greater than the maximum lateral distance the halyard 12 may sway due to external forces such as wind. And because the distance of sway will vary as a function of the distance from a securing structure, i.e., a cleat below or a eye hook above (neither shown), the distance the halyard 12 must be from the flagstaff 14 to prevent these collisions. Therefore, only one arm means 16 is needed so long as the arm means 12 is long enough to separate the halyard 12 from the flagstaff 12 at the securing structures a sufficient distance. Halyard restricting means 24 is disposed adjacent the distal end 20 of the arm means 16 for removably securing the halyard 12 at the distal end 20 of the arm means 16. The halyard restricting means 24 includes at least one slot 26 having a portion 28 extending substantially parallel to the longitudinal axis A. The portion 28 restricts the movement of the halyard 12 so it may only move in a direction parallel to the longitudinal axis A. In other words, the halyard 12 is abutted on three sides by the halyard restricting means 24 with the remaining forth side free from any abutment with the halyard restricting means 24. The halyard 12, however, can move in this free direction due to the tension created by the halyard 12 being tied down at the cleat (not shown) below. Therefore, the wind cannot blow the halyard 12 out of the halyard restricting means 24 when the wind blows in a direct having a directional component perpendicular to the longitudinal axis A. By having a portion 28 of the slot 26 being parallel to the longitudinal axis A, the subject invention 10 eliminates the need for latches or other movable means of restraining the halyard 12 from moving in a lateral direction. In the preferred embodiment, as best shown in FIG. 2, the halyard restraining means 24 includes a plurality of slots 26, one for each section of the halyard 12 extending the length of the flagstaff 14. Typically, the halyard 12 extends the length of the flagstaff 14 only twice, to facilitate the raising and the lowering of one article. Therefore, two slots 26 are shown spaced equidistant from the longitudinal axis A in FIG. 2. In addition, the halyard restricting means 24 is wider than the body portion 22 of the arm means 16. The reduction in the width of the arm means 16 past the halyard restricting means 24 reduces the weight and cost of the subject invention 10 while increasing the ease in mounting same. The subject invention 10 further includes base means, generally indicated at 30, fixedly securable to the flagstaff 14 for supporting the arm means 16 at the base end 18 of the arm means 16. Because the base means 30 will usually be secured to a flagstaff 14, the base means 30 has an arcuate mounting surface 32 facing oppositely to the flanges 34, discussed subsequently, for fixedly securing the assembly 10 to the flagstaff 14. Although there exists several different means for fastening the base means 30 to the flagstaff 14 known to those skilled in the art, the base means 30 is secured to the flagstaff 14 using sheet metal screws (not shown) which extend through holes 36 in the base means 30. In the preferred embodiment, two holes 36 are shown. Rotating means, generally shown at 38, supports the arm means 16 at the base end 18 for rotating the arm means 16 about the base end 18. The rotation of the arm means 16 is relative to the base means 30. The rotating means 38 includes holding means, generally indicated at 40, extending out from the base means 30. The rotating means 38 also includes a first pin, generally indicated at 42, which extends through the holding means 40 and the arm means 16. The first pin 42 comprises a solid cylindrical body 44 having a head 46 and a retainer receiving groove 48 at either end of the cylindrical body 44. The first pin 42 is inserted through two holes 50, discussed subsequently, in the holding means 40 and through a second hole 52 in the arm means 16. The head 46 prevents the first pin 42 from passing therethrough. A circlip 54 is inserted into the retainer receiving groove 48 after the first pin 42 is fully inserted into the holding means 40. The retainer receiving groove 48 may be replaced by equivalent retaining structures. By way of example only, alternative retaining structures may include, but are not limited to, a hole and cotter pin combination or a threaded end and nut combination. The holding means 40 is further characterized by including at least one flange 34 extending out from the base means 30 and having a first hole 50 for receiving the first pin 42. In the preferred embodiment of the subject invention 10, the holding means 40 includes a plurality of flanges 34, namely two flanges 34, which extend out and away from the base means 30 on either side of the arm means 16. Each of the flanges 34 include first receiving means 56 for receiving locking means 58. The first receiving means 56 comprise a hole 56 in each of the flanges 40 which are aligned with each other. Said another way, the first receiving means 56 includes at least one pair of aligned holes extending through the flanges 34. The locking means 58 locks the arm means 16 in any one of a plurality of rotational positions relative to the base means 30. The locking means includes a second pin 58. The second pin 58 also has a head 60 for restricting the movement of the second pin 58 so it will not move beyond any of the flanges 40. The head 60 may include a ring 62 to aid in the removal of the second pin 58. The base end 18, and more particularly, the rotating means 38 of the base end 18 further includes second receiving means 64 for receiving the second pin 58 therein. The arm means 16 will be locked into a distinct position when the second pin 58 is inserted through both the first 56 and second 64 receiving means. The second receiving means includes at least one hole 64 extending through the base end 18 of the arm means 16. In the preferred embodiment, a plurality of holes 64 extend through the base end 18 of the arm means 16. The pair of holes 56 extending through the flanges 40 and the plurality of holes 64 are concentrically disposed about the first pin 42. In addition, they 56,64 are also alignable. In other words, the distance between the center first holes 50 and the pair of holes 56 are equal to each other and equal to the distance between the centers of the second hole 52 and the plurality of holes 64. Therefore, when the arm means 16 is rotated to one of its plurality of positions, i.e., an operating position and a storage position (shown in phantom in FIG. 1), one of the plurality of holes 64 will align with the pair of holes 56. Upon alignment, the second pin 58 may be inserted therein thus locking the arm means 16 in the chosen position. Turning attention to FIGS. 3 and 4, where like numerals refer to like or similar parts, two alternative designs for the halyard retaining means 124,224 are shown, respectively. In FIG. 3, the plurality of slots 126, each having a longitudinal portion 128 substantially parallel to the longitudinal axis A, include fully enclosed peripheries. Said another way, the plurality of slots 126 are disposed adjacent the distal end 120 of the arm means 116 such that the plurality of slots 126 are closed. Therefore, the plurality of slots 126 do not come into contact with the periphery of the arm means 116. The distal end 120 is a flat surface in this first alternative embodiment. In the second alternative embodiment, as shown in FIG. 4, the plurality of slots 226 comprise first 228 and second 200 portions extending laterally with respect to the longitudinal axis A. In other words, the plurality of slots 226 come into contact with or open out at the longitudinal sides 202 of the halyard restraining means 224. The first portions 228 have first 230 and second 232 ends wherein the second ends 232 are disposed adjacent the distal end 220 of the arm means 216. Said another way, the first ends 230 point toward the base end 18 and the second ends 232 point toward the distal end 220. The second portions 200 extend outwardly from the second ends 232. The second portions 200 may extend out laterally toward the longitudinal sides 202 at any angle. Although it is shown in FIG. 4 to be an acute angle with respect to the first portion 228 of the slots 226, the angle may be equal to or greater than ninety degrees. As in the first alternative embodiment, the distal end 220 of the arm means 216 is a flat surface in the second alternative embodiment. The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims wherein reference numerals are merely for convenience and are not to be in any way limiting, the invention may be practiced otherwise than as specifically described.
A halyard retainer (10) eliminates noise created by the halyard (12) hitting a flagstaff (14) by retaining the halyard (12) at a greater distance than would normally separate the halyard (12) from the flagstaff (14). A base (30) fixedly secures the halyard retainer (10) to the flagstaff (14). The halyard restrictor (24) is at the distal end (20) of an arm (16) and includes two slots (26). The longitudinal portions (28) of the slots (26) allow the halyard retainer (10) to hold the halyard (12) without additional latches or locks. The arm (16) is rotatable about a first pin (42) between an operating position and a storage position and is locked into one of the two positions using a second pin (58).
Provide a concise summary of the essential information conveyed in the context.
[ "BACKGROUND ART 1.", "Technical Field The subject invention relates to cord and rope holders.", "More particularly, the subject invention relates to a pivoting halyard retainer.", "Description of Related Art Flagstaffs and masts are used to support articles, typically made of fabric, high above the reach of man.", "The flagstaffs and masts, hereinafter referred to as flagstaffs, are thin pole-shaped structures used as unobtrusive structures to support these articles, such as flags, sails, pennants, and the like.", "The standard method of hoisting the flag or sail is stringing a rope, or halyard, up through an eye hook at the top of the flagstaff and back down to the ground attaching the flag to the halyard.", "The halyard is secured at the bottom of the flagstaff via a cleat.", "The flag is lifted by pulling one half of the halyard down thus pulling the other end of the halyard up through the eye hook.", "The flag is then lifted up to the top of the flagstaff.", "When the flag is to be removed, the opposite end of the halyard is pulled.", "A problem arises when a wind is present.", "Noise is produced between the halyard and the flagstaff when the halyard collides with the flagstaff because of it flapping in the wind.", "This problem becomes particularly bothersome at night because the noise keeps everyone in the vicinity awake.", "Outside of releasing the halyard to flap freely in the wind presumably away from the flagstaff, which is not a very satisfying solution, for sailors in particular, there is no known remedy.", "U.S. Pat. No. 4,313,391 to Hall issued Feb. 2, 1982, discloses a mast shroud system for spreading support the shrouds of a mast to aid in the attachment and removal of the shrouds to and from the mast.", "Although this system effectively moves the shrouds away from the mast, thus reducing the amount of noise created by the shroud hitting the mast, this system does not contemplate the separation of the halyards from the mast.", "The shroud system is not capable of handling halyards which must be used, raised and lowered, on a regular basis.", "The nature of the shrouds are to support the mast and will not be frequently removed.", "In addition, the mast shroud system must always be used and, therefore, has no need nor even capability to be stored in an unobtrusive position.", "U.S. Pat. No. 876,770 to Brundell, issued Jan. 14, 1908, discloses a rope holding device for securing a rope used to open and close curtains.", "The rope holding device comprises an arm with a notch extending from the interior of the arm out to the periphery of the arm in a direction perpendicular to the longitudinal axis of the arm.", "The device further includes a spring loaded sleeve which is forced by the spring out over the notch in the arm.", "Therefore, when the rope is inserted into the notch, the sleeve clamps the rope in place not allowing it to move.", "Additionally, a support arm is attached to the arm via the sleeve to prevent the arm from rotating due to a force which may be applied to the arm by the clamped rope.", "A stop prevents the arm and support arm from collapsing against the wall when not in use by restricting the amount of clockwise rotation.", "This system is inadequate for reducing the amount of noise created by the halyard hitting the flagstaff because a lateral wind is capable of overcoming the lateral force created by the longitudinal force of the spring loaded sleeve.", "The rope will be subsequently forced out of the holder.", "The rope holding device is designed for indoor use and is not designed to withstand the forces that it may encounter in an outdoor environment having gusting winds and storms.", "The rope would be freed from its holder and begin to flap in the wind and, invariably, create the irritating noise of the halyard hitting the flagstaff.", "SUMMARY OF THE INVENTION AND ADVANTAGES A halyard retaining assembly for eliminating noise produced by a halyard colliding with a pole structure comprises arm means.", "The arm means has a base end and a distal end defining a longitudinal axis therebetween for extending the halyard away from the pole structure.", "The base means is fixedly securable to the pole structure for supporting the arm means at the base end.", "Halyard restricting means is disposed adjacent the distal end of the arm means for removably securing the halyard at the distal end of the arm means.", "Rotating means supports the arm means on the base end for rotating the arm means about the base end relative to the base means.", "The assembly is characterized by the halyard restricting means including at least one slot having a portion extending substantially parallel to the longitudinal axis.", "The assembly eliminates the method of releasing the halyards to fly in the wind by retaining the halyard out and away from the flagstaff thus eliminating any noise which may be produced by the halyard coming into contact with the flagstaff.", "An added advantage of the subject invention is that it can be rotated to a stored position so it will be visually less obtrusive when it is not as important that the halyards are hitting the flagstaff.", "BRIEF DESCRIPTION OF THE DRAWINGS Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: FIG. 1 is a side view of the preferred embodiment of the subject invention;", "FIG. 2 is an exploded perspective view of the preferred embodiment cf the subject invention;", "FIG. 3 is a fragmentary plan view of a first alternative embodiment of the subject invention;", "and FIG. 4 is a fragmentary plan view of a second alternative embodiment of the subject invention.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, wherein like numerals indicate like or corresponding parts throughout the several views, the subject invention is a flagstaff attached halyard retainer and is generally shown at 10.", "The subject invention 10 eliminates the irritating noise created by a halyard 12 hitting a pole structure 14, such as a flagstaff or a mast, due to any wind which may be present.", "For simplicity, the pole structure 14 will hereinafter be referred to as a flagstaff 14.", "The subject invention 10 includes arm means, generally indicated at 18.", "The arm means 16 has a base end 18 and a distal end 20 with a body 22 extending therebetween defining a longitudinal axis A. The arm means 16 extends the halyard 12 out and away from the flagstaff 14.", "The arm means 16 does not increase the tension in the halyard 12;", "it moves the halyard 12 away from the flagstaff 14 a distance greater than the maximum lateral distance the halyard 12 may sway due to external forces such as wind.", "And because the distance of sway will vary as a function of the distance from a securing structure, i.e., a cleat below or a eye hook above (neither shown), the distance the halyard 12 must be from the flagstaff 14 to prevent these collisions.", "Therefore, only one arm means 16 is needed so long as the arm means 12 is long enough to separate the halyard 12 from the flagstaff 12 at the securing structures a sufficient distance.", "Halyard restricting means 24 is disposed adjacent the distal end 20 of the arm means 16 for removably securing the halyard 12 at the distal end 20 of the arm means 16.", "The halyard restricting means 24 includes at least one slot 26 having a portion 28 extending substantially parallel to the longitudinal axis A. The portion 28 restricts the movement of the halyard 12 so it may only move in a direction parallel to the longitudinal axis A. In other words, the halyard 12 is abutted on three sides by the halyard restricting means 24 with the remaining forth side free from any abutment with the halyard restricting means 24.", "The halyard 12, however, can move in this free direction due to the tension created by the halyard 12 being tied down at the cleat (not shown) below.", "Therefore, the wind cannot blow the halyard 12 out of the halyard restricting means 24 when the wind blows in a direct having a directional component perpendicular to the longitudinal axis A. By having a portion 28 of the slot 26 being parallel to the longitudinal axis A, the subject invention 10 eliminates the need for latches or other movable means of restraining the halyard 12 from moving in a lateral direction.", "In the preferred embodiment, as best shown in FIG. 2, the halyard restraining means 24 includes a plurality of slots 26, one for each section of the halyard 12 extending the length of the flagstaff 14.", "Typically, the halyard 12 extends the length of the flagstaff 14 only twice, to facilitate the raising and the lowering of one article.", "Therefore, two slots 26 are shown spaced equidistant from the longitudinal axis A in FIG. 2. In addition, the halyard restricting means 24 is wider than the body portion 22 of the arm means 16.", "The reduction in the width of the arm means 16 past the halyard restricting means 24 reduces the weight and cost of the subject invention 10 while increasing the ease in mounting same.", "The subject invention 10 further includes base means, generally indicated at 30, fixedly securable to the flagstaff 14 for supporting the arm means 16 at the base end 18 of the arm means 16.", "Because the base means 30 will usually be secured to a flagstaff 14, the base means 30 has an arcuate mounting surface 32 facing oppositely to the flanges 34, discussed subsequently, for fixedly securing the assembly 10 to the flagstaff 14.", "Although there exists several different means for fastening the base means 30 to the flagstaff 14 known to those skilled in the art, the base means 30 is secured to the flagstaff 14 using sheet metal screws (not shown) which extend through holes 36 in the base means 30.", "In the preferred embodiment, two holes 36 are shown.", "Rotating means, generally shown at 38, supports the arm means 16 at the base end 18 for rotating the arm means 16 about the base end 18.", "The rotation of the arm means 16 is relative to the base means 30.", "The rotating means 38 includes holding means, generally indicated at 40, extending out from the base means 30.", "The rotating means 38 also includes a first pin, generally indicated at 42, which extends through the holding means 40 and the arm means 16.", "The first pin 42 comprises a solid cylindrical body 44 having a head 46 and a retainer receiving groove 48 at either end of the cylindrical body 44.", "The first pin 42 is inserted through two holes 50, discussed subsequently, in the holding means 40 and through a second hole 52 in the arm means 16.", "The head 46 prevents the first pin 42 from passing therethrough.", "A circlip 54 is inserted into the retainer receiving groove 48 after the first pin 42 is fully inserted into the holding means 40.", "The retainer receiving groove 48 may be replaced by equivalent retaining structures.", "By way of example only, alternative retaining structures may include, but are not limited to, a hole and cotter pin combination or a threaded end and nut combination.", "The holding means 40 is further characterized by including at least one flange 34 extending out from the base means 30 and having a first hole 50 for receiving the first pin 42.", "In the preferred embodiment of the subject invention 10, the holding means 40 includes a plurality of flanges 34, namely two flanges 34, which extend out and away from the base means 30 on either side of the arm means 16.", "Each of the flanges 34 include first receiving means 56 for receiving locking means 58.", "The first receiving means 56 comprise a hole 56 in each of the flanges 40 which are aligned with each other.", "Said another way, the first receiving means 56 includes at least one pair of aligned holes extending through the flanges 34.", "The locking means 58 locks the arm means 16 in any one of a plurality of rotational positions relative to the base means 30.", "The locking means includes a second pin 58.", "The second pin 58 also has a head 60 for restricting the movement of the second pin 58 so it will not move beyond any of the flanges 40.", "The head 60 may include a ring 62 to aid in the removal of the second pin 58.", "The base end 18, and more particularly, the rotating means 38 of the base end 18 further includes second receiving means 64 for receiving the second pin 58 therein.", "The arm means 16 will be locked into a distinct position when the second pin 58 is inserted through both the first 56 and second 64 receiving means.", "The second receiving means includes at least one hole 64 extending through the base end 18 of the arm means 16.", "In the preferred embodiment, a plurality of holes 64 extend through the base end 18 of the arm means 16.", "The pair of holes 56 extending through the flanges 40 and the plurality of holes 64 are concentrically disposed about the first pin 42.", "In addition, they 56,64 are also alignable.", "In other words, the distance between the center first holes 50 and the pair of holes 56 are equal to each other and equal to the distance between the centers of the second hole 52 and the plurality of holes 64.", "Therefore, when the arm means 16 is rotated to one of its plurality of positions, i.e., an operating position and a storage position (shown in phantom in FIG. 1), one of the plurality of holes 64 will align with the pair of holes 56.", "Upon alignment, the second pin 58 may be inserted therein thus locking the arm means 16 in the chosen position.", "Turning attention to FIGS. 3 and 4, where like numerals refer to like or similar parts, two alternative designs for the halyard retaining means 124,224 are shown, respectively.", "In FIG. 3, the plurality of slots 126, each having a longitudinal portion 128 substantially parallel to the longitudinal axis A, include fully enclosed peripheries.", "Said another way, the plurality of slots 126 are disposed adjacent the distal end 120 of the arm means 116 such that the plurality of slots 126 are closed.", "Therefore, the plurality of slots 126 do not come into contact with the periphery of the arm means 116.", "The distal end 120 is a flat surface in this first alternative embodiment.", "In the second alternative embodiment, as shown in FIG. 4, the plurality of slots 226 comprise first 228 and second 200 portions extending laterally with respect to the longitudinal axis A. In other words, the plurality of slots 226 come into contact with or open out at the longitudinal sides 202 of the halyard restraining means 224.", "The first portions 228 have first 230 and second 232 ends wherein the second ends 232 are disposed adjacent the distal end 220 of the arm means 216.", "Said another way, the first ends 230 point toward the base end 18 and the second ends 232 point toward the distal end 220.", "The second portions 200 extend outwardly from the second ends 232.", "The second portions 200 may extend out laterally toward the longitudinal sides 202 at any angle.", "Although it is shown in FIG. 4 to be an acute angle with respect to the first portion 228 of the slots 226, the angle may be equal to or greater than ninety degrees.", "As in the first alternative embodiment, the distal end 220 of the arm means 216 is a flat surface in the second alternative embodiment.", "The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.", "Obviously, many modifications and variations of the present invention are possible in light of the above teachings.", "It is, therefore, to be understood that within the scope of the appended claims wherein reference numerals are merely for convenience and are not to be in any way limiting, the invention may be practiced otherwise than as specifically described." ]
TECHNICAL FIELD [0001] This patent application describes a MEMS microphone (MEMS=Micro Electromechanical System). BACKGROUND [0002] U.S. Pat. No. 4,816,125 describes a MEMS microphone with a piezoelectric layer made from ZnO and several electrodes connected to this layer that are arranged concentrically. [0003] The following publication describes a microphone module with an encapsulated MEMS microphone, in which an enclosed air volume (back volume) is in a housing underneath the microphone's diaphragm: J. J. Neumann, Jr. and K. J. Gabriel, “A fully integrated CMOS-MEMS audio microphone,” the 12th International Conference on Solid State Sensors, Actuators, and Microsystems, 2003 IEEE, pp. 230-233. [0004] The following publication describes an electrical module with an installed MEMS piezoresistive microphone: D. P. Arnold, et al., “A directional acoustic array using silicon micromachined piezoresistive microphones,” J. Acoust. Soc. Am., Vol. 113(1), 2003, pp. 289-298. [0005] The following publication describes a piezoelectric microphone, which has two piezoelectric layers made from ZnO and a floating electrode arranged in-between: Mang-Nian Niu and Eun Sok Kim, “Piezoelectric Bimorph Microphone Built on Micromachined Parylene Diaphragm,” Journal of Microelectromechanical Systems, Vol. 12, 2003 IEEE, pp. 892-898. SUMMARY [0006] Described herein is a sensitive microphone with a high signal-to-noise ratio. [0007] It has been found that microphones that detect sound pressure using diaphragms are usually dependent on a large diaphragm displacement as a reaction to sound intensity in order to achieve desired characteristics in terms of sensitivity and noise behavior. For small components with built-in microphones, achievable displacement is limited by small diaphragm area. When diaphragm displacement is converted into an electrical quantity, only weak electrical signals can be obtained. The elasticity of a diaphragm produced in a deposition process can be negatively affected by a bias caused by a high internal mechanical stress. [0008] MEMS microphones described here have an air chamber connected to a sound inlet opening and also a back volume. An enclosed air volume that prevents an acoustic short circuit—an undesired pressure balance between the front and back sides of the oscillating diaphragm—is referred to as a back volume. This air volume generates a restoring force for each diaphragm displacement in addition to the restoring force caused by the elastic diaphragm characteristics. For small components, the back volume is so small that even small diaphragm displacements lead to a considerable increase in pressure in the back volume, which can be on the order of magnitude of the sound level to be detected. The additional restoring force decreases the elasticity and the displacement of the diaphragm. [0009] A microphone is described with a first and a second diaphragm, which are each connected to one and the same closed air volume and are thus coupled to each other so that, for a displacement of the first diaphragm, a simultaneous displacement of the second diaphragm is generated. [0010] The first diaphragm is a microphone diaphragm, i.e., a “passive” diaphragm, which detects the sound pressure or converts an acoustic signal into an electrical signal. The second diaphragm is an auxiliary diaphragm or an “active” diaphragm, whose displacement generated by electrical driving interacts with the “passive” diaphragm via the closed air volume. [0011] Two different strategies are described for the electrically driving the active diaphragm: [0012] 1) “Holding the enclosed air volume constant”: For this purpose, a signal derived from the passive diaphragm and amplified is fed to the active diaphragm such that the active diaphragm performs an opposite but equal-magnitude motion that is similar or identical to that of the passive diaphragm. For example, if the passive diaphragm is driven to a certain volume displacement towards the interior of the cavity by the external sound pressure, then an electrical driving of the active diaphragm by the approximately equivalent volume displacement away from the interior of the cavity is realized. As a result, the fluctuation of the chamber volume is reduced or eliminated. In this way, it is possible to reduce pressure fluctuations caused by the sound pressure in the closed air volume considerably, e.g., by at least a factor of two, in one embodiment by at least a factor of five. This reduction in internal pressure fluctuations, however, also means a corresponding reduction in the diaphragm restoring force. The effective back volume thus appears significantly enlarged, in the limiting case as infinite. [0013] 2) “Compensation of the passive diaphragm displacement”: Here, the electrical driving of the active diaphragm is part of a control circuit that reduces or even eliminates the displacement of the passive diaphragm, despite the effect of the external acoustic field on the passive diaphragm. A measure for this displacement is the electrical output signal of the passive diaphragm, which is held close to zero by the control circuit. At each moment, the active diaphragm establishes, for this purpose, an internal pressure in the chamber, which is close or equal to the external pressure (sound pressure). The resulting differential pressure for the passive diaphragm is reduced or disappears completely, which also applies to its displacement. Without significant diaphragm displacement of the passive diaphragm, however, the back volume causes, in turn, no relevant restoring forces on this diaphragm. The output signal of the arrangement in this case is not that of the passive diaphragm (which is definitely driven to zero in the described way), but instead the drive signal of the active diaphragm formed in the control circuit. [0014] In both cases, a virtual back volume is achieved that is greater than the real back volume by a multiple (in one construction by at least two times, in one embodiment construction by at least five times). [0015] The two circuit-related strategies for reducing the effective restoring force run the risk of building up feedback oscillations in the entire system. In one embodiment, therefore, circuit-related measures are provided for recognizing and preventing such conditions. [0016] In a first construction, a microphone is specified with a body in which two openings are provided, which open into a cavity formed in the body. A first diaphragm is arranged over a first opening and a second diaphragm (auxiliary diaphragm) is arranged over a second opening, so that an air volume is enclosed in the cavity. The second diaphragm may be decoupled acoustically from the exterior by another cavity. A space in which the source of an acoustic input signal is located is referred to as the exterior. [0017] A chamber that is connected to the exterior and isolated from the cavity is arranged over the first diaphragm. The cavity is designated below as the back volume. [0018] The first diaphragm is arranged in a first cavity wall over an opening formed in this wall. In one embodiment, the second diaphragm is arranged in a second cavity wall. The diaphragms may be arranged in opposite cavity walls. Because the acoustic pressure change is transmitted equally in all directions when the diaphragm is dispersed, it is also possible to arrange the two diaphragms in walls standing at right angles to each other. The two diaphragms can be arranged in the same cavity wall. [0019] The two diaphragms may have essentially the same mass and can be formed identically. The (passive) first diaphragm acts as a microphone diaphragm, while the (driven) second diaphragm functions as a loudspeaker diaphragm. In the case of a piezoelectric MEMS microphone based on the direct piezoelectric effect, for example, the displacement of the first diaphragm is converted into an electrical signal. In a capacitive MEMS microphone, the relative position of the electrodes of the microphone changes. The associated change in capacitance is converted into an electrical signal. The respective diaphragm can be basically an electromechanical converter operating with an electric field or magnetic field. [0020] The displacement of the second diaphragm can be generated like in a loudspeaker, e.g., by a changing electric or magnetic field. The displacement of the second diaphragm with piezoelectric properties can be generated on the basis of the inverse piezoelectric effect. [0021] In an embodiment, both diaphragms each have at least one piezoelectric layer. Both diaphragms may be constructed identically. Alternatively, it is possible for the electromechanical conversion in the diaphragms to be based on different electromechanical effects. For example, the first diaphragm can function as a capacitive MEMS microphone and the second diaphragm can function as a piezoelectric converter. [0022] In one embodiment, a vent opening can be provided, which connects the enclosed air volumes (back volume of the microphone) and the exterior and which is small relative to the cross-sectional size of the diaphragm and which is used for slow pressure balancing, e.g., in the range of ≧100 ms. The pressure balancing is performed slowly relative to the period of an acoustic signal with the largest wavelength in the operating range of the microphone. This opening can be arranged in the diaphragm or in a wall of the container that encloses the acoustic back volume. [0023] By virtue of the described compensation measures according to the first and the second embodiment, it is possible to reduce the real acoustic back volume (i.e., the closed air volume) relative to known microphones without an auxiliary diaphragm, so that space savings can be achieved. Nevertheless, because the virtual back volume can be kept sufficiently large, no disadvantageous consequences (loss of sensitivity) occur due to the smaller construction. [0024] To prevent an acoustic short circuit of a driven auxiliary diaphragm to the exterior or to the sound inlet opening, an additional cavity isolated from the exterior is provided in an advantageous variant as an acoustic back volume for the auxiliary diaphragm. The additional cavity is separated by the auxiliary diaphragm from the closed air volume. The additional cavity can be smaller than the closed air volume, because the auxiliary diaphragm is driven actively and thus its displacement is set. The space requirements of the microphone arrangement can accordingly be kept small overall. [0025] A microphone will be explained in detail below on the basis of embodiments and the associated figures. The figures show different embodiments of the microphone on the basis of schematic representations that are not to scale. Parts that are identical or that have identical functions are labeled with the same reference symbols. DESCRIPTION OF THE DRAWINGS [0026] FIG. 1A , a part of a microphone according to a first embodiment, comprising two electrically coupled diaphragms in a schematic cross section; [0027] FIG. 1B , equivalent circuit diagram of the microphone according to FIG. 1A ; [0028] FIGS. 2 , 3 , each a variant of the embodiment shown in FIG. 1 ; [0029] FIG. 4A , a part of a microphone according to the second variant; [0030] FIG. 4B , equivalent circuit diagram of the microphone according to FIG. 4A ; [0031] FIG. 5 , an example microphone diaphragm in a schematic cross section; [0032] FIG. 6 , a metal layer, in which two electrodes connected electrically to external contacts are formed. DETAILED DESCRIPTION [0033] FIG. 1A shows a microphone with a body GH, which has openings AU 1 , AU 2 opening into a cavity HR 2 on its opposing walls HW 1 , HW 2 . A first diaphragm M 1 (microphone diaphragm, passive diaphragm) is arranged over the first opening AU 1 and a second diaphragm M 2 (auxiliary diaphragm, driven diaphragm) is arranged over the second opening AU 2 . [0034] The diaphragm M 1 , M 2 can be mounted on the walls of the body GH. Alternatively, the diaphragm M 1 , M 2 can be replaced by a microphone chip with a carrier substrate and a diaphragm mounted thereon. The microphone chip can be connected fixedly to the body GH, e.g., by an adhesive layer. [0035] The first diaphragm M 1 separates the cavity HR 2 from a chamber HR 1 , which is connected to the exterior via a sound inlet opening IN. The first diaphragm M 1 begins to vibrate as soon as an acoustic pressure p is exerted on it. The change in pressure in the chamber HR 1 and the vibration of the diaphragm M 1 would lead to a change in volume or pressure in the cavity HR 2 (without the auxiliary diaphragm M 2 ) and an associated restoring force, which acts on the first diaphragm M 1 and reduces the vibration amplitude. Due to an electrical coupling of the two diaphragms M 1 , M 2 , they vibrate in such a manner that the displacement of the first diaphragm M 1 is towards the interior of the cavity HR 2 and the displacement of the second diaphragm M 2 is realized with the same amplitude towards the outside. The active diaphragm M 2 is driven in a push-pull way with respect to the passive first diaphragm M 1 . Here, a reduced change or no change at all in the volume of the cavity HR 2 occurs. [0036] The second diaphragm M 2 separates the cavity HR 2 from an additional closed cavity HR 3 , which is isolated from a space connected to a sound source, i.e., the exterior and the chamber HR 1 . The additional cavity HR 3 prevents feedback of the active diaphragm onto the passive diaphragm on the outer path. [0037] The additional cavity HR 3 and/or the chamber HR 1 can be created, e.g., by a cap-shaped, dimensionally stable cover. [0038] In FIG. 1B , a simplified equivalent circuit diagram of diaphragms M 1 , M 2 coupled by a control circuit V 1 is shown. For a displacement of the passive diaphragm M 1 caused by the sound pressure, an electrical signal is generated that can be tapped at the output OUT as a usable signal for further processing. A part of the electrical signal is used for generating a control signal at the output of the control circuit V 1 , with which the auxiliary diaphragm M 2 is driven in a push-pull way (relative to the internal pressure established in the cavity HR 2 ) with respect to the passive diaphragm. [0039] The drive circuit V 1 may contain an amplifier for amplifying the signal tapped at the diaphragm M 1 . [0040] FIG. 2 shows an embodiment of the microphone presented in FIG. 1 , in which both diaphragms M 1 , M 2 are arranged in the same cavity wall HW 1 . In a cavity wall of the cavity HR 2 , a small ventilation opening VE connecting this cavity and the exterior is provided, whose cross-sectional size is clearly smaller (e.g., by at least a factor of 100) than the cross-sectional size of the diaphragm or the openings AU 1 or AU 2 and which is used for slow pressure balancing, e.g., in the range of ≧100 ms. In a cavity wall of the cavity HR 3 , a small ventilation opening VE′ connecting this cavity and the exterior is also provided. [0041] In FIG. 3 , the openings AU 1 , AU 2 are provided in mutually perpendicular walls. The ventilation opening VE is formed here in the diaphragm M 1 . [0042] The direction of the diaphragm displacement is indicated with arrows in FIGS. 1 to 4A , B. [0043] In a variant of the embodiment presented in FIG. 4A , the active second diaphragm M 2 is driven in a push-pull way (relative to the internal pressure) with the passive first diaphragm M 1 in contrast to FIG. 1A . Here, the displacements of the two diaphragms are directed towards the interior of the air volume enclosed in the cavity HR 2 . In FIG. 4A , a dashed line shows how the passive diaphragm M 1 would deform due to external sound pressure. A solid line shows the actual position of the diaphragm M 1 achieved due to the compensating effect of the active diaphragm M 2 , wherein the diaphragm M 1 remains practically in its rest position or oscillates with a very small amplitude relative to the displacement of the active diaphragm M 2 . [0044] FIG. 4B shows an equivalent circuit diagram to the embodiment according to FIG. 4A . The electrical signal tapped at the diaphragm M 1 is processed by the control circuit RK. On one hand, a control signal for driving the diaphragm M 2 is output and, on the other, another control signal, which is superimposed on the signal tapped at the diaphragm M 1 and damps the oscillation amplitude of the diaphragm M 1 . An output signal at the output OUT can be evaluated. The output OUT is connected here to the diaphragm M 2 . [0045] In the variants presented in FIGS. 2 and 3 , it is also possible to drive the active diaphragm M 2 in common mode relative to the passive diaphragm M 1 , in order to damp the displacement amplitude of the passive diaphragm M 1 in addition to the restoring force acting on this diaphragm. [0046] FIG. 4B shows the equivalent circuit diagram of a microphone, which comprises a control circuit RK for compensating the displacement of the diaphragm M 1 . The output signal OUT 2 is obtained here from the control circuit, while the signal of the converter M 1 is held close to zero by the effect of the control. An example of a diaphragm with a piezoelectric layer PS arranged between two metal layers ML 1 , ML 2 is shown in FIGS. 5 and 6 . Electrodes E 11 and E 12 connected to the external contacts AE 1 , AE 2 are arranged in the first metal layer ML 1 . A floating conductive area, which lies opposite the two electrodes E 11 , E 12 , is formed in the second metal layer ML 2 . Here, two capacitors connected to each other in series are formed. [0047] In FIG. 6 , a first metal layer ML 1 of the diaphragm presented in FIG. 5 is shown. The round electrode E 11 is arranged in a first high-potential region and the annular electrode E 12 is arranged in a second high-potential region. The two high-potential regions have opposite polarity. The electrodes E 11 , E 12 are each connected to external contacts AE 1 and AE 2 , respectively. In a metal layer ML 2 arranged underneath or above and shown in FIG. 5 , a continuous, floating, conductive surface may be arranged, which is opposite the two electrodes E 11 , E 12 . [0048] The microphone is not limited to the number of elements shown in the figures or to the acoustically audible range from 20 Hz to 20 kHz. The microphone can also be used in other piezoelectric acoustic sensors, e.g., distance sensors operating with ultrasound. A microphone chip with a described microphone can be used in any signal-processing module. Different embodiments can also be combined with each other.
A microphone includes a first diaphragm and a second diaphragm coupled to the first diaphragm by a closed air volume. The first diaphragm and the second diaphragm each constitutes a piezoelectric diaphragm. The first diaphragm and the second diaphragm are electrically coupled so that movement of the first diaphragm causes movement of the second diaphragm.
Summarize the patent information, clearly outlining the technical challenges and proposed solutions.
[ "TECHNICAL FIELD [0001] This patent application describes a MEMS microphone (MEMS=Micro Electromechanical System).", "BACKGROUND [0002] U.S. Pat. No. 4,816,125 describes a MEMS microphone with a piezoelectric layer made from ZnO and several electrodes connected to this layer that are arranged concentrically.", "[0003] The following publication describes a microphone module with an encapsulated MEMS microphone, in which an enclosed air volume (back volume) is in a housing underneath the microphone's diaphragm: J. J. Neumann, Jr. and K. J. Gabriel, “A fully integrated CMOS-MEMS audio microphone,” the 12th International Conference on Solid State Sensors, Actuators, and Microsystems, 2003 IEEE, pp. 230-233.", "[0004] The following publication describes an electrical module with an installed MEMS piezoresistive microphone: D. P. Arnold, et al.", ", “A directional acoustic array using silicon micromachined piezoresistive microphones,” J. Acoust.", "Soc.", "Am.", ", Vol. 113(1), 2003, pp. 289-298.", "[0005] The following publication describes a piezoelectric microphone, which has two piezoelectric layers made from ZnO and a floating electrode arranged in-between: Mang-Nian Niu and Eun Sok Kim, “Piezoelectric Bimorph Microphone Built on Micromachined Parylene Diaphragm,” Journal of Microelectromechanical Systems, Vol. 12, 2003 IEEE, pp. 892-898.", "SUMMARY [0006] Described herein is a sensitive microphone with a high signal-to-noise ratio.", "[0007] It has been found that microphones that detect sound pressure using diaphragms are usually dependent on a large diaphragm displacement as a reaction to sound intensity in order to achieve desired characteristics in terms of sensitivity and noise behavior.", "For small components with built-in microphones, achievable displacement is limited by small diaphragm area.", "When diaphragm displacement is converted into an electrical quantity, only weak electrical signals can be obtained.", "The elasticity of a diaphragm produced in a deposition process can be negatively affected by a bias caused by a high internal mechanical stress.", "[0008] MEMS microphones described here have an air chamber connected to a sound inlet opening and also a back volume.", "An enclosed air volume that prevents an acoustic short circuit—an undesired pressure balance between the front and back sides of the oscillating diaphragm—is referred to as a back volume.", "This air volume generates a restoring force for each diaphragm displacement in addition to the restoring force caused by the elastic diaphragm characteristics.", "For small components, the back volume is so small that even small diaphragm displacements lead to a considerable increase in pressure in the back volume, which can be on the order of magnitude of the sound level to be detected.", "The additional restoring force decreases the elasticity and the displacement of the diaphragm.", "[0009] A microphone is described with a first and a second diaphragm, which are each connected to one and the same closed air volume and are thus coupled to each other so that, for a displacement of the first diaphragm, a simultaneous displacement of the second diaphragm is generated.", "[0010] The first diaphragm is a microphone diaphragm, i.e., a “passive”", "diaphragm, which detects the sound pressure or converts an acoustic signal into an electrical signal.", "The second diaphragm is an auxiliary diaphragm or an “active”", "diaphragm, whose displacement generated by electrical driving interacts with the “passive”", "diaphragm via the closed air volume.", "[0011] Two different strategies are described for the electrically driving the active diaphragm: [0012] 1) “Holding the enclosed air volume constant”: For this purpose, a signal derived from the passive diaphragm and amplified is fed to the active diaphragm such that the active diaphragm performs an opposite but equal-magnitude motion that is similar or identical to that of the passive diaphragm.", "For example, if the passive diaphragm is driven to a certain volume displacement towards the interior of the cavity by the external sound pressure, then an electrical driving of the active diaphragm by the approximately equivalent volume displacement away from the interior of the cavity is realized.", "As a result, the fluctuation of the chamber volume is reduced or eliminated.", "In this way, it is possible to reduce pressure fluctuations caused by the sound pressure in the closed air volume considerably, e.g., by at least a factor of two, in one embodiment by at least a factor of five.", "This reduction in internal pressure fluctuations, however, also means a corresponding reduction in the diaphragm restoring force.", "The effective back volume thus appears significantly enlarged, in the limiting case as infinite.", "[0013] 2) “Compensation of the passive diaphragm displacement”: Here, the electrical driving of the active diaphragm is part of a control circuit that reduces or even eliminates the displacement of the passive diaphragm, despite the effect of the external acoustic field on the passive diaphragm.", "A measure for this displacement is the electrical output signal of the passive diaphragm, which is held close to zero by the control circuit.", "At each moment, the active diaphragm establishes, for this purpose, an internal pressure in the chamber, which is close or equal to the external pressure (sound pressure).", "The resulting differential pressure for the passive diaphragm is reduced or disappears completely, which also applies to its displacement.", "Without significant diaphragm displacement of the passive diaphragm, however, the back volume causes, in turn, no relevant restoring forces on this diaphragm.", "The output signal of the arrangement in this case is not that of the passive diaphragm (which is definitely driven to zero in the described way), but instead the drive signal of the active diaphragm formed in the control circuit.", "[0014] In both cases, a virtual back volume is achieved that is greater than the real back volume by a multiple (in one construction by at least two times, in one embodiment construction by at least five times).", "[0015] The two circuit-related strategies for reducing the effective restoring force run the risk of building up feedback oscillations in the entire system.", "In one embodiment, therefore, circuit-related measures are provided for recognizing and preventing such conditions.", "[0016] In a first construction, a microphone is specified with a body in which two openings are provided, which open into a cavity formed in the body.", "A first diaphragm is arranged over a first opening and a second diaphragm (auxiliary diaphragm) is arranged over a second opening, so that an air volume is enclosed in the cavity.", "The second diaphragm may be decoupled acoustically from the exterior by another cavity.", "A space in which the source of an acoustic input signal is located is referred to as the exterior.", "[0017] A chamber that is connected to the exterior and isolated from the cavity is arranged over the first diaphragm.", "The cavity is designated below as the back volume.", "[0018] The first diaphragm is arranged in a first cavity wall over an opening formed in this wall.", "In one embodiment, the second diaphragm is arranged in a second cavity wall.", "The diaphragms may be arranged in opposite cavity walls.", "Because the acoustic pressure change is transmitted equally in all directions when the diaphragm is dispersed, it is also possible to arrange the two diaphragms in walls standing at right angles to each other.", "The two diaphragms can be arranged in the same cavity wall.", "[0019] The two diaphragms may have essentially the same mass and can be formed identically.", "The (passive) first diaphragm acts as a microphone diaphragm, while the (driven) second diaphragm functions as a loudspeaker diaphragm.", "In the case of a piezoelectric MEMS microphone based on the direct piezoelectric effect, for example, the displacement of the first diaphragm is converted into an electrical signal.", "In a capacitive MEMS microphone, the relative position of the electrodes of the microphone changes.", "The associated change in capacitance is converted into an electrical signal.", "The respective diaphragm can be basically an electromechanical converter operating with an electric field or magnetic field.", "[0020] The displacement of the second diaphragm can be generated like in a loudspeaker, e.g., by a changing electric or magnetic field.", "The displacement of the second diaphragm with piezoelectric properties can be generated on the basis of the inverse piezoelectric effect.", "[0021] In an embodiment, both diaphragms each have at least one piezoelectric layer.", "Both diaphragms may be constructed identically.", "Alternatively, it is possible for the electromechanical conversion in the diaphragms to be based on different electromechanical effects.", "For example, the first diaphragm can function as a capacitive MEMS microphone and the second diaphragm can function as a piezoelectric converter.", "[0022] In one embodiment, a vent opening can be provided, which connects the enclosed air volumes (back volume of the microphone) and the exterior and which is small relative to the cross-sectional size of the diaphragm and which is used for slow pressure balancing, e.g., in the range of ≧100 ms.", "The pressure balancing is performed slowly relative to the period of an acoustic signal with the largest wavelength in the operating range of the microphone.", "This opening can be arranged in the diaphragm or in a wall of the container that encloses the acoustic back volume.", "[0023] By virtue of the described compensation measures according to the first and the second embodiment, it is possible to reduce the real acoustic back volume (i.e., the closed air volume) relative to known microphones without an auxiliary diaphragm, so that space savings can be achieved.", "Nevertheless, because the virtual back volume can be kept sufficiently large, no disadvantageous consequences (loss of sensitivity) occur due to the smaller construction.", "[0024] To prevent an acoustic short circuit of a driven auxiliary diaphragm to the exterior or to the sound inlet opening, an additional cavity isolated from the exterior is provided in an advantageous variant as an acoustic back volume for the auxiliary diaphragm.", "The additional cavity is separated by the auxiliary diaphragm from the closed air volume.", "The additional cavity can be smaller than the closed air volume, because the auxiliary diaphragm is driven actively and thus its displacement is set.", "The space requirements of the microphone arrangement can accordingly be kept small overall.", "[0025] A microphone will be explained in detail below on the basis of embodiments and the associated figures.", "The figures show different embodiments of the microphone on the basis of schematic representations that are not to scale.", "Parts that are identical or that have identical functions are labeled with the same reference symbols.", "DESCRIPTION OF THE DRAWINGS [0026] FIG. 1A , a part of a microphone according to a first embodiment, comprising two electrically coupled diaphragms in a schematic cross section;", "[0027] FIG. 1B , equivalent circuit diagram of the microphone according to FIG. 1A ;", "[0028] FIGS. 2 , 3 , each a variant of the embodiment shown in FIG. 1 ;", "[0029] FIG. 4A , a part of a microphone according to the second variant;", "[0030] FIG. 4B , equivalent circuit diagram of the microphone according to FIG. 4A ;", "[0031] FIG. 5 , an example microphone diaphragm in a schematic cross section;", "[0032] FIG. 6 , a metal layer, in which two electrodes connected electrically to external contacts are formed.", "DETAILED DESCRIPTION [0033] FIG. 1A shows a microphone with a body GH, which has openings AU 1 , AU 2 opening into a cavity HR 2 on its opposing walls HW 1 , HW 2 .", "A first diaphragm M 1 (microphone diaphragm, passive diaphragm) is arranged over the first opening AU 1 and a second diaphragm M 2 (auxiliary diaphragm, driven diaphragm) is arranged over the second opening AU 2 .", "[0034] The diaphragm M 1 , M 2 can be mounted on the walls of the body GH.", "Alternatively, the diaphragm M 1 , M 2 can be replaced by a microphone chip with a carrier substrate and a diaphragm mounted thereon.", "The microphone chip can be connected fixedly to the body GH, e.g., by an adhesive layer.", "[0035] The first diaphragm M 1 separates the cavity HR 2 from a chamber HR 1 , which is connected to the exterior via a sound inlet opening IN.", "The first diaphragm M 1 begins to vibrate as soon as an acoustic pressure p is exerted on it.", "The change in pressure in the chamber HR 1 and the vibration of the diaphragm M 1 would lead to a change in volume or pressure in the cavity HR 2 (without the auxiliary diaphragm M 2 ) and an associated restoring force, which acts on the first diaphragm M 1 and reduces the vibration amplitude.", "Due to an electrical coupling of the two diaphragms M 1 , M 2 , they vibrate in such a manner that the displacement of the first diaphragm M 1 is towards the interior of the cavity HR 2 and the displacement of the second diaphragm M 2 is realized with the same amplitude towards the outside.", "The active diaphragm M 2 is driven in a push-pull way with respect to the passive first diaphragm M 1 .", "Here, a reduced change or no change at all in the volume of the cavity HR 2 occurs.", "[0036] The second diaphragm M 2 separates the cavity HR 2 from an additional closed cavity HR 3 , which is isolated from a space connected to a sound source, i.e., the exterior and the chamber HR 1 .", "The additional cavity HR 3 prevents feedback of the active diaphragm onto the passive diaphragm on the outer path.", "[0037] The additional cavity HR 3 and/or the chamber HR 1 can be created, e.g., by a cap-shaped, dimensionally stable cover.", "[0038] In FIG. 1B , a simplified equivalent circuit diagram of diaphragms M 1 , M 2 coupled by a control circuit V 1 is shown.", "For a displacement of the passive diaphragm M 1 caused by the sound pressure, an electrical signal is generated that can be tapped at the output OUT as a usable signal for further processing.", "A part of the electrical signal is used for generating a control signal at the output of the control circuit V 1 , with which the auxiliary diaphragm M 2 is driven in a push-pull way (relative to the internal pressure established in the cavity HR 2 ) with respect to the passive diaphragm.", "[0039] The drive circuit V 1 may contain an amplifier for amplifying the signal tapped at the diaphragm M 1 .", "[0040] FIG. 2 shows an embodiment of the microphone presented in FIG. 1 , in which both diaphragms M 1 , M 2 are arranged in the same cavity wall HW 1 .", "In a cavity wall of the cavity HR 2 , a small ventilation opening VE connecting this cavity and the exterior is provided, whose cross-sectional size is clearly smaller (e.g., by at least a factor of 100) than the cross-sectional size of the diaphragm or the openings AU 1 or AU 2 and which is used for slow pressure balancing, e.g., in the range of ≧100 ms.", "In a cavity wall of the cavity HR 3 , a small ventilation opening VE′ connecting this cavity and the exterior is also provided.", "[0041] In FIG. 3 , the openings AU 1 , AU 2 are provided in mutually perpendicular walls.", "The ventilation opening VE is formed here in the diaphragm M 1 .", "[0042] The direction of the diaphragm displacement is indicated with arrows in FIGS. 1 to 4A , B. [0043] In a variant of the embodiment presented in FIG. 4A , the active second diaphragm M 2 is driven in a push-pull way (relative to the internal pressure) with the passive first diaphragm M 1 in contrast to FIG. 1A .", "Here, the displacements of the two diaphragms are directed towards the interior of the air volume enclosed in the cavity HR 2 .", "In FIG. 4A , a dashed line shows how the passive diaphragm M 1 would deform due to external sound pressure.", "A solid line shows the actual position of the diaphragm M 1 achieved due to the compensating effect of the active diaphragm M 2 , wherein the diaphragm M 1 remains practically in its rest position or oscillates with a very small amplitude relative to the displacement of the active diaphragm M 2 .", "[0044] FIG. 4B shows an equivalent circuit diagram to the embodiment according to FIG. 4A .", "The electrical signal tapped at the diaphragm M 1 is processed by the control circuit RK.", "On one hand, a control signal for driving the diaphragm M 2 is output and, on the other, another control signal, which is superimposed on the signal tapped at the diaphragm M 1 and damps the oscillation amplitude of the diaphragm M 1 .", "An output signal at the output OUT can be evaluated.", "The output OUT is connected here to the diaphragm M 2 .", "[0045] In the variants presented in FIGS. 2 and 3 , it is also possible to drive the active diaphragm M 2 in common mode relative to the passive diaphragm M 1 , in order to damp the displacement amplitude of the passive diaphragm M 1 in addition to the restoring force acting on this diaphragm.", "[0046] FIG. 4B shows the equivalent circuit diagram of a microphone, which comprises a control circuit RK for compensating the displacement of the diaphragm M 1 .", "The output signal OUT 2 is obtained here from the control circuit, while the signal of the converter M 1 is held close to zero by the effect of the control.", "An example of a diaphragm with a piezoelectric layer PS arranged between two metal layers ML 1 , ML 2 is shown in FIGS. 5 and 6 .", "Electrodes E 11 and E 12 connected to the external contacts AE 1 , AE 2 are arranged in the first metal layer ML 1 .", "A floating conductive area, which lies opposite the two electrodes E 11 , E 12 , is formed in the second metal layer ML 2 .", "Here, two capacitors connected to each other in series are formed.", "[0047] In FIG. 6 , a first metal layer ML 1 of the diaphragm presented in FIG. 5 is shown.", "The round electrode E 11 is arranged in a first high-potential region and the annular electrode E 12 is arranged in a second high-potential region.", "The two high-potential regions have opposite polarity.", "The electrodes E 11 , E 12 are each connected to external contacts AE 1 and AE 2 , respectively.", "In a metal layer ML 2 arranged underneath or above and shown in FIG. 5 , a continuous, floating, conductive surface may be arranged, which is opposite the two electrodes E 11 , E 12 .", "[0048] The microphone is not limited to the number of elements shown in the figures or to the acoustically audible range from 20 Hz to 20 kHz.", "The microphone can also be used in other piezoelectric acoustic sensors, e.g., distance sensors operating with ultrasound.", "A microphone chip with a described microphone can be used in any signal-processing module.", "Different embodiments can also be combined with each other." ]
RELATED APPLICATIONS U.S. utility-patent application Ser. No. 08/055,660 of Gregory D. Raskin, filed on Apr. 30, 1993, and issued as U.S. Pat. No. 5,426,457 on Jun. 20, 1995, is relevant to certain aspects of the present invention as will be explained hereunder, and is hereby incorporated in its entirety into the present document. BACKGROUND 1. Field of the Invention This invention relates generally to inkjet printing systems in which an image (characters or graphics, or both) is constructed on a printing medium as an array of many individually computer-controlled inkdrops; and more particularly to a method for printing such an array which minimizes undesired artifacts that arise in the inkjet printing process. 2. Related Art An inkjet image can be created through any one of myriad different inkjet nozzle firing patterns, implemented by specific program steps of a microprocessor. Such program steps are usually provided in the form of firmware for a general-purpose programmable microprocessor, but fixed arrays of electronic logic elements can be used instead. Any such firing pattern is called a "print mode". Print-mode variations encompass special uses of a pen or different portions of a pen in coordination with choice of printing-medium advance distance or frequency, special suppressions of firing for specified nozzles, and special choices of nozzle timing (as, for example, during scanning in different directions). Many different print modes are used to accomplish many different purposes. Such objectives include, for instance, high speed, or more accurate hue for specific printing media, or subtle reduction of the total amount of liquid ink present on a piece of print medium at one time, or (as in the Raskin patent document mentioned above) better alignment of forward and return scans in bidirectional printing, or masking of subtle printing defects--such as arise, for example, from cyclical variations or other imperfections in print-medium advance distance, or from isolated nonfiring nozzles, or from internozzle variations in ink volume. It is believed that heretofore all print modes known in the art have been devised on the implicit assumption that inkdrops, and (with respect to print quality) assemblages of inkdrops, are symmetrical. Thus it has been taken for granted that a drop deposited on a printing medium by a pen while scanning in one direction (for instance, from left to right) looks the same as a drop deposited by the same pen while scanning in the opposite direction (such as from right to left). Accordingly it has been implicitly assumed that inkdrop arrays deposited during scanning in different directions look the same--or, to put it in still another way, that image quality at both sides of a drop, or both sides of an assemblage of drops, is the same. If this were true, both sides of every image element would be equally good, or equally bad, so (given mutual alignment of image portions deposited during opposite-direction scans) it wouldn't matter which way the pen moved while printing different parts of each image element. It has been pointed out, however, that these implicit assumptions are false, or in other words that inkdrops or at least assemblages of them do indeed have good sides and bad sides. Careful inspection and study of inkjet-printed images reveals an image-quality asymmetry, correlated with the direction of pen scanning. Specifically, each distinct image element is cleaner on the side from which the pen moves toward that element than it is on the side toward which the pen moves from the same element. This difference appears to be due to a tendency of minute amounts of extremely fine spray, associated with firing of the pen, to overshoot the target position very slightly. Sometimes workers in this field refer to such spray as the "tail" of the inkdrop or as a "secondary dot". In any event it presents the appearance of a slight blurring, irregularity or dirtiness of the associated trailing part of what has been printed. Evidently this spray, tail or secondary dot results at least in part from lower average speed of fine particles in the direction normal to the printing medium, and therefore longer transit time between the nozzle and the medium. Such lower average speed may result from the processes that generate the spray, or possibly the effectively greater air damping for small particles, or both. (Even though damping force decreases with area, the effect of such drag is greater for small particles because mass and therefore momentum decrease with volume. Another possible contributor to offsetting of the spray is downwind drift of fine particles in the wake of the pen carriage. It will be understood that the utility of the present invention, to be described shortly, does not rest on the accuracy of any of these speculations.) After conventional bidirectional printing, the blurring effect is present at both sides of each image element, and so the original asymmetry of print quality for each element is concealed. After conventional unidirectional printing, the blur is present at only one side. Earlier thinking addressed to mitigating this print-quality defect may have concentrated on cocking or angling each nozzle to somehow align the tail or secondary dot with the main or primary dot. In any event in commercial practice this defect or at least part of it remains. Still other known print-quality defects have not been satisfactorily addressed in configuring print modes. In particular it is known that, when very wide continuous image areas are printed all at once, creating a large pool of liquid ink, undesired so-called "wicking" and "runners" occur; these are visible small streams of ink, representing paths of ink movement by capillarity through fibers of the printing medium and away from the area where the ink has been deposited. Heretofore print modes have addressed overinking problems either by (1) subtlely suppressing the total amount of ink on a printed image, or (2) allowing more drying time by dividing each image segment into checker-board-like subgroupings for printing in successive pen scans, the division being arbitrary--that is, without regard for the particular pattern or characteristics of image elements being printed. Both these techniques are ingenious, and they do ameliorate other overinking problems (such as offsetting, and adhesion of adjacent sheets) on which the present discussion does not focus, as well as misalignment between adjacent pen swaths; yet these techniques do have drawbacks. Suppressing the total amount of ink has some at least slight adverse effects on hue accuracy and color saturation. More importantly--since such ink reduction is willy-nilly, i. e. not correlated, with respect to image characteristics--overall ink suppression may unduly starve some image areas that actually are not subject to wicking. Dividing image segments for printing in three or more successive scans has the disadvantage of increasing the required printing time. It may do so needlessly in image areas free of wicking and runners. As noted above, wicking is most serious for broad expanses of continuous inking. On the other hand, when only very narrow portions are printed, edges objectionably reveal the pixel structure conspicuously as a distinct scalloped or serrated pattern, because surface tension is inadequate to pull the ink pool into a more-nearly straight border. Earlier print modes have not effectively addressed this problem. As will be apparent it tends--whenever present--to be exacerbated by the overall ink-suppression or multiscan image divisions discussed above. Another known print-quality impairment relevant to the present invention, and to other bidirectional printing systems, is misalignment between scans in opposite directions. This problem is manifested as a narrow line of unprinted or background color (for example white) where adjacent pixel blocks, printed in opposite-direction scans, fail to merge visually into a single apparent image element. The aforementioned Raskin patent document offers one valuable solution to such problems, though it depends for its full effectiveness upon good consistency of motor speeds in the reverse or retrace direction. That solution can evidently avoid narrow unprinted gaps where blocks of pixels laid down in opposite directions fail to be spaced properly at the regular pixel periodicity. It may not, however, cure a gap in which failure to visually merge results from inadequate wicking between the two blocks, due to one being already dry. A simpler solution to interscan misalignments, and one which may help to avoid this particular problem, could be useful. Heretofore these considerations have not been taken into account in devising print modes for best print quality. Thus important aspects of the technology used in the field of the invention are amenable to useful refinement. SUMMARY OF THE DISCLOSURE Part of the creative contribution of the present invention resides in the recognition that, since the implicit assumption of drop symmetry described above are in fact false, an additional degree of freedom is available for optimization of print quality. In fact print quality is subject to refinement and enhancement through print modes based on correcting that assumption; the present invention introduces such refinement. Before offering a relatively rigorous discussion of the present invention, some informal orientation will be provided here. It is to be understood that these first comments are not intended as a statement of the invention. They are simply in the nature of insights that will be helpful in comprehending the principles upon which the invention is based. The invention exploits the above-described asymmetry to improve apparent overall quality by forcing the less-perfect side of each image element to become, and to be hidden within, the interior of that image element. To achieve this effect, certain strategically selected parts of each element are printed during scanning of the pen in one direction and certain other parts during scanning in an opposite direction. Neither scan prints the trailing edge--that is, the edge the pen reaches last, when moving in a particular direction. Printing the trailing edge, as in conventional print modes, would allow the above-mentioned fine spray to be projected beyond that edge into what should be a background (for example, white) area free of the color being printed--thereby generating a very slightly dirty or blurry edge. Instead each scan prints only the leading edge--plus the interior or part of the interior, if the image is wide enough that its interior forms an analytically separate portion. If the image is wider still, it is subdivided and the subparts associated, for printing purposes, with the leading edges respectively. Thus one discrete interior portion is printed in the same scan with one of the lateral edges (the leading edge in one scan direction). An additional discrete interior portion is printed in the same scan with the other of the lateral edges (the leading edge in the opposite scan direction). In any event, during scanning in a first direction much of the previously mentioned fine spray that arises from printing of the leading edge and interior portion is deposited within the area that should be the trailing edge--and this area is filled in solidly at the beginning of the scan in a second or opposite direction, for which the area under discussion is a leading edge. Complementarily the fine spray from that scan is deposited within the area that is filled in solidly at the beginning of the first-direction scan. In short a large fraction of the fine spray is hidden within a solid field of ink of the same color. Such spray from the first-occurring scan is buried in a later solid edge formed in the second-occurring scan; and such spray from the second-occurring scan is imperceptible because it overprints the solid edge formed in the first. This discussion suggests that the width of a "leading edge" preferably is great enough to encompass all or most of the overshoot or drift distance of the spray. Attempting to thus capture all the spray, however, may be counterproductive in forcing use of leading-edge width to be larger than desirable with respect to other criteria. In particular, the width of a "leading edge" is best defined to optimize print quality by concealing most of the fine spray and also finding the best tradeoff between two oppositely acting surface-tension effects mentioned earlier: Objectionable wicking or runners appear when very wide portions are printed all at once, creating a large pool of liquid ink. This effect tends to favor defining the "edges" as narrow. Objectionable scalloped or serrated patterns appear when only very narrow portions are printed. This effect favors defining the "edges" as wide. Overlap dots can be included in the portion printed in either or both directions. Such dots avoid narrow unprinted gaps in case of misalignment between scans in opposite directions--and also in case of inadequate wicking to help merge adjacent blocks printed in different scans. Now with these preliminary observations in mind this discussion will proceed to a perhaps more-formal summary. The present invention has at least three main facets or aspects, which are amenable to practice independently of each other--although for best enjoyment of the benefits of the invention they are preferably used together. In preferred embodiments of all of these three major aspects, the present invention is a method of printing images as an array of many pixels, using a bidirectionally scanning inkjet pen. In a first of the three main aspects or facets, the method includes the step of--while scanning the pen in a first direction--printing the leading edge of an image element and refraining from printing the trailing edge of that element. The phrase "the leading edge" means the leading edge with respect to that first direction. More specifically yet, the leading edge "with respect to" a given scan direction is the edge which the moving pen reaches first when traveling in that direction (here, the stated "first direction"). The method also includes the step of--while scanning the pen in a second direction opposite to the first direction--printing the leading edge of the same image element and refraining from printing the trailing edge of that element. Here "the leading edge" means the leading edge with respect to the second direction, which is to say the edge which the pen reaches first when traveling in the second direction. The foregoing may be a description or definition of the first major facet of the present invention in its broadest or most general terms. Even in such general or broad forms, however, as can now be seen the first facet of the invention refines and enhances the art of inkjet printing. In particular this new print mode tends to significantly enhance the image quality by concealing fine spray within the interior of each image element. Although the invention thus provides very significant advances relative to the prior art, nevertheless for greatest enjoyment of the benefits of the invention it is preferably practiced in conjunction with certain other features or characteristics which enhance its benefits. For example, it is preferred that the method further include the step of--while scanning the pen in the first direction--also printing at least one interior portion of the same image element. When the interior of an image element is large enough to be subdivided, preferably the interior portion is separated from the leading edge printed while scanning the pen in the first direction, and is substantially adjacent to the leading edge printed while scanning the pen in the second direction. This separation has the beneficial effect of avoiding the printing of overwide edges, and thereby avoiding generation of runners, mentioned earlier. In addition the method further includes the step of, while scanning the pen in the second direction, also printing at least one additional interior portion of the same image element. This additional interior portion is separated (for the same reason as just stated with respect to the first direction) from the leading edge printed while scanning the pen in the second direction, and is substantially adjacent to the leading edge printed while scanning the pen in the first direction. In such cases it is preferable too that the method include the step of--before printing either leading edge--analyzing the image element. Such analysis is used to determine which pixel columns are leading edges with respect to each scanning direction, which pixel columns are the first-mentioned interior portion, and which pixel columns are the additional interior portion. As suggested earlier the invention forces the trailing edge of each image element to become, and to be hidden within, the interior of that element. In abstract or philosophical effect each image element is folded inward upon itself to protect the viewer from relatively poorer-quality edges, like the rolled rough edges of a sheet-metal part that are hidden by a solid portion of the same part. As a practical matter, however, it may be more meaningful to say that each image element is strategically subdivided into subelements, and each of these subelements is printed in a way that is subject to the intrinsic asymmetry of print quality, and therefore is subject to print-quality defects--but the subelements are reassembled to form the starting, desired image element in such a way that solid portions of the subelements hide the defects. I have found that further significant image enhancement can be achieved by preferably also including a step of--before printing either leading edge--analyzing the image element to determine too which pixel rows are top edge, bottom edge, and vertically middle segment of each image element. In a related step, these top and bottom edge rows, above and below the previously mentioned "additional interior" portion, are associated with the leading edge and first-mentioned interior portion printed in the first direction, for printing during scanning in the first direction; and the top and bottom edge rows, above and below the first-mentioned interior portion, are associated with the leading edge and additional interior portion printed in the second direction, for printing during scanning in the second direction. In these preferred cases it is further preferable that the analyzing steps further include selecting the number of pixel columns to serve as leading edges in such a way as to optimize print quality; and also selecting the number of pixel rows to serve as top and bottom edges in such a way as to optimize print quality. More specifically the analyzing step preferably includes selecting the number of pixel columns to serve as leading edges in such a way as to obtain an optimum tradeoff between adverse effects of runners and adverse effects of surface tension. Methods in accordance with the first aspect of the invention preferably include performing the image-element analysis for all elements in the image--that is to say, before printing an image, analyzing the entire image to determine which pixel columns are leading edges of image elements within the image, with respect to each scanning direction. In preferred embodiments of a second of its main facets or aspects the method of the invention includes the steps of: while scanning the pen from left to right, printing the left edge of an image element and refraining from printing the right edge of that element; and while scanning the pen from right to left, printing the right edge of the same image element and refraining from printing the left edge of that element. In preferred embodiments of a third of its main facets the method includes the step of analyzing an image element to determine which pixel rows should be treated as the top edge, bottom edge, and vertically middle part, respectively, of the element; and to determine which pixel columns should be treated as the left and right edges, and first and second interior portions, respectively, of the element. In this third facet the analyzing step includes selecting the number of rows to treat as top and bottom edges in such a way as to optimize image quality. The method also includes the steps of: while scanning the pen in one direction, printing the top and bottom edges above and below the first interior portion; and while scanning the pen in a second, opposite, direction, printing the top and bottom edges above and below the second interior portion. All of the foregoing operational principles and advantages of the present invention will be more fully appreciated upon consideration of the following detailed description, with reference to the appended drawings, of which: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a very schematic diagram showing in isometric or perspective view what is meant by "leading edge" and "trailing edge" in an inkjet printing context for pen movement from left to right; FIG. 2 is a like view for pen movement from right to left; FIG. 3 is a reproduction of a photographic record, greatly enlarged, of a narrow vertical line printed on an inkjet printer; FIG. 4 is a view like FIGS. 1 and 2 showing one step of a print-mode method according to the present invention; FIG. 5 is a like view showing a later step of the same print-mode method; FIG. 6 is an idealized illustration of a relationship between line thickness and edge quality--showing in particular the effects of surface-tension smoothing and runners; FIG. 7 is a diagram of the same relationship in a somewhat more quantified form; FIG. 8 is a schematic representation of simplified pixel-wise division of a horizontal line into outside edges and a single interior portion in accordance with the present invention; FIG. 9 is a like representation of simplified division of a horizontal line into outside edges and two interior portions, also in accordance with the invention; FIG. 10 is a like representation of a two-dimensional image element printed in two passes, using the FIG. 9 division; FIG. 11 is a like representation of simplified division of a vertical line into top, bottom and vertically middle portions; FIG. 12 is a like representation of the use of an overlap dot to prevent image defects due to interscan misalignments; FIG. 13 is a view like FIG. 10 but showing preliminarily how the simplified horizontal-division method of FIG. 9 is integrated with the simplified vertical-division method of FIG. 11, in printing a single image element; FIG. 14 is a related view showing an algorithm for operating on the FIG. 13 blocks; FIG. 15 is a three-step progressive view like FIG. 10 but showing how the integrated but preliminary scheme of FIGS. 13 and 14 is carried on to complete implementation; and FIG. 16 is a photographic reproduction of four greatly enlarged photographic records of a word printed on an inkjet printer, contrasting performance of the print mode of the invention with three conventional print modes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 1. Trailing and Leading Edges As used in this document, the terms leading edge and trailing edge are determined by the scan direction of the printer carriage. "Leading edge" designates the first edge of the vertical line printed, and "trailing edge" refers to the last edge printed. FIG. 1 shows in three successive subviews the printing of a vertical line 1, 2 two pixels wide onto a sheet 52 of paper or other printing medium, when the pen 51 is scanning 53, 55 from left to right, and identifies the associated leading edge 1 and trailing edge 2. In the first (left-hand) subview, during its rightward scanning motion 53 the pen 51 ejects a first column of inkdrops 54. In the second (center) subview those drops are seen to have formed on the print-medium sheet 52 a column 1 of pixels--this will be the so-called "leading edge" of the finished line. To the right of each dot in the first column 1 there has been drawn, in this second subview of FIG. 1, a narrow rightward protuberance or extension 3. This tail-like extension 3 symbolizes the so-called "secondary dot" mentioned earlier, and will be discussed in some detail shortly. Also in this second subview, the pen 51, while continuing to move 55 in the same direction, is seen to be ejecting a second column of drops 56. In the third (right-hand) subview the pen 51 has completed its scan, and the second column of drops is seen to have formed on the sheet 52 another column 2 of pixels--the so-called "trailing edge" of the finished line. Here the leading edge 1 is the left side of the line and the trailing edge 2 is the right side. In this view the protrusions from the first column 1 of dots, however, are no longer visible: they have been buried in the more massive ink deposit of the second column 2. Each of the dots 2 in the second column, however, has been drawn with a rightward tail-like protrusion 3 similar to those of the first column. Thus no matter how many pixel columns are aggregated in this fashion the rightmost column is accompanied by a column of secondary dots that are visible. A more accurate, photographic representation of this disturbance appears in FIG. 3, which demonstrates a typical difference between the leading- and trailing-edge quality of a printed line. As seen in FIG. 3, the leading edge 1 more closely approximates a straight line. The sharpness of the trailing edge 2 is irregular 3 due both to edge roughness and to increased amount of spray; the overall result is that the print quality of the leading edge 1 is superior to that of the trailing edge 2. FIG. 2 shows phenomena analogous to those of FIG. 1, for printing of a like line 1', 2' when the pen 51 is moving 63 from right to left. The first subview (in this case the right-hand subview) portrays the pen 51 moving 63 leftward and ejecting a first column 64 of drops. These drops in the second (central) subview are seen to have formed on the sheet 52 a first column 1' of pixels--the "leading edge" in this leftward scan--together with an associated column 3' of secondary dots, which in this case are leftward from the column 1' of primary dots rather than rightward as in FIG. 1. The second subview also shows a second column 66 of drops being ejected while the pen 51 continues its leftward scan 65. The third subview in FIG. 2 shows the resulting two-pixel-wide line on the sheet 52 after the pen 51 has completed its scan--namely, the leading edge 1' on the right and trailing edge 2' on the left. Once again the first column of secondary dots has been buried in the second column 2' of primary dots, but in this third subview a new array of secondary dots 3' has been created--still leftward from the associated primary pixel column 2'. FIGS. 1 and 2 demonstrate that: the leading edge 1, 1' can be at either the right or left side of the printed vertical line, depending on the direction 53/55, 63/65 respectively in which the pen 51 moves; and an irregularity, symbolized in these drawings by the tail-like secondary dots 3, 3', always appears at the trailing edge 2, 2' of any unidirectionally printed inkjet image. It can be appreciated from this presentation that like irregularities 3, 3' appear as well at both edges of any inkjet image printed bidirectionally, if such an image is printed using a conventional print mode known heretofore. It will be understood that these drawings are only examples. Analogous identifications of leading and trailing edges can be established for systems in which pen scanning occurs along axes other than the horizontal--whether vertical or oriented at arbitrary angles. Since leading edges 1 are superior to trailing edges 2, it is desirable that all vertical edges printed be leading. This can be accomplished by using a bidirectional print mode as described below for a like two-pixel-wide line. As the pen carriage moves 73 from left to right (FIG. 4), the pen 51 ejects inkdrops 74 to create a first column 1 of dots (pixels), which will constitute a leading edge of the finished line. In FIG. 4 as in FIGS. 1 and 2, the roughness on the trailing side of this pixel column 1 has been incorporated into the illustration, symbolized by a rightward extension or elongation 3, corresponding to the irregularities 3 of FIG. 3. The direction of pen-carriage scanning is then reversed (FIG. 5). While the pen scans leftward it ejects a second column 84 of drops to make a second column 1' of dots on the sheet 52. Thus both edges 1, 1' of the resulting vertical line are leading edges. The second column 1' of dots, however, now buries the secondary dots 3 associated with the first column 1 of dots--and the secondary dots 3' created in the process of generating the second column 1' overprints the first column 1 of like-color dots. As a result of this strategic superposition, neither column of secondary dots can be seen. This advantageous result will obtain regardless of the number of adjacent columns aggregated, provided only that one or two dot columns along each edge are printed while the pen scans into the aggregation of columns from the adjacent unprinted or background area. (In some extreme cases the irregularity or secondary-dot phenomenon may extend over more than one pixel width. For such cases, for vertical lines more than three columns wide, it is desirable that the dots printed as the "leading edge" consist of two pixel columns rather than just one.) 2. Line Width The quality of a vertical-line edge depends on the line thickness, or width--the number of dot/pixel columns that make up the line. In a vertical line 13 (FIG. 6) only one dot wide, there is often not enough ink for the surface tension to smooth out the vertical edges; therefore these exhibit a marked scalloping effect 4, a series of pronounced inward-pointing cusps. As more ink is laid down--for instance in a two-column-wide line 14--the vertical edges 5 become somewhat smoother but perhaps not entirely straight. As the width of the line continues to grow, perhaps to a three-column line 15, the vertical edges may be much more nearly straight, but another effect becomes noticeable: The amount of ink laid down begins to be excessive, and the extra ink starts to move by capillarity--or "wick"--into the paper fibers, causing visible runners 7 to extend or "feather" outward from the edges. The extent of both edge smoothness and feathering 7 depends strongly on the ink formulation and type of printing medium in use; however, as a general matter while the number of columns solidly printed continues to increase (as exemplified at 16 in FIG. 6) eventually the edges 8 become quite straight but the number and length of runners 9 worsen severely. To integrate these observations, the important trends observed with increase of the number of pixel columns are (1) edge smoothing 8 and (2) feathering 7, 9. FIG. 7 shows how the two trends can be optimized in a quasi quantitative sense. In FIG. 7 the PQ ("print quality") scale from "good" to "bad" quantifies on a common, standardized basis the visual perception of both runners 107/109 and surface-tension smoothing 108, using as a PQ measure the areal deviation per unit length of line. The areal deviation is the printed area that extends beyond a smoothed, average-position edge (in this case rectilinear). Thus an ideal or "good" edge has PQ=0 (as it too, for this case, is rectilinear). The PQ sum or aggregate 110 goes through a minimum, which is an optimum point 110 for the particular combination of printing medium and ink formulation in use. With respect to horizontal lines, a further distinction is useful: the distinction is between the boundary 10, 10' (FIG. 8) and interior 20 of the line. The boundary of a horizontal line is, or boundaries are, the first and last dot segments 10, 10' that compose the line. For optimal results either or each boundary may consist of two or more dots. For instance two dots are shown as making up only the left-hand portion of the boundary 10 in the first subview of FIG. 8, but both left- and right-hand portions of the boundary 10' in the third subview. One can divide the horizontal line even further into a right-side component and a left-side one. This results in four sections (FIG. 9) for each horizontal line: left end or edge 11, right edge 12, left interior portion 21 and right interior portion 22. 3. Integration of Leading-Edge, Optimum-Width and Element-Subdivision Concepts Integration of the above concepts results in an optimized print mode. The three concepts to be integrated are: two-pass, bidirectional, leading-edge-only printing; optimal line width; and the four horizontal-line subdivisions. To print an image element (a representation of an object, an alphanumeric character, etc.) in a two-pass mode requires dividing the element into two main components, one to be printed on each pass, such that when the two components are together on the printing medium the original image element appears. A further criterion for this print mode is that, when possible, both the right and left boundary thicknesses are optimized. To construct of the two main components, the interior of the image element is divided into two portions and each portion paired with its opposite boundary. For example a left inside portion 21 (FIG. 10) is part of the same main component as--and is printed in the same pass 31 with--the right boundary or edge 12; and the right inside portion 22 is part of the same main component as, and printed in the same pass 32 with, the left edge 11. In FIG. 10 all of the stippled dots 31 make up the material printed in one pass (for instance a first pass), and all of the "X"-filled dots 32 make up the material printed in another pass (for instance a second pass). As will be seen shortly, FIG. 10 represents a simplified special case of applying a more general algorithm; the illustrated print mode is the simplest expression of the three concepts listed at the beginning of this section. A root understanding is that print quality is dependent on the order and method by which dots are placed on the page. 4. Overlap Pixels, and Vertical Divisions To further refine the optimization, one can find the optimal boundary thickness for both horizontal and vertical lines. This suggests that even a narrow (e.g., one-pixel wide) vertical line should be split into three parts--top 41 (FIG. 11), bottom 42, and vertically middle 43. In this part of the process it should not be assumed that the same thickness is optimal for both directions. Directionality of paper grain, for instance, could have an influence on the extent of surface-tension effects. When two dot groups 31a, 32a (FIG. 12) placed by pen scans in two opposite directions, respectively, are mutually well aligned, the groups are spaced apart horizontally by the same spacing as pixel columns within each group. The result, as in the right side of the first (top) subview of FIG. 12, is that the groups 31a, 32a merge to look like a continuous horizontal line--or, in a taller image element (e. g., wide vertical line), a continuous field. In case of imperfections in dot-placement accuracy of the printing system, particularly interscan misalignments as between opposite-direction pen scans, another refinement may be needed. One effect of such misalignment can be a small displacement 33b between the groups of dots, as seen at left in the second (center) subview of FIG. 12. Such misalignment results (right side of second subview) in interruption of the finished composite image element by a narrow white (or other background-color) gap 33--or vertical stripe 33, for a taller image element. For elements just two pixels wide (not shown in FIG. 12) the only solution may be to improve interscan tolerances. One particularly effective way of doing so is set forth in the previously mentioned Gregory D. Raskin co-pending patent document, incorporated by reference into this document. The Raskin technique can be used for the case of wider lines as well, and for both cases should substantially eliminate the objectionable stripe 33. For wider lines, however, another solution is to guarantee overlap of adjoining segments as by providing an additional overlap dot 34 (third subview in FIG. 12). As will be understood by people skilled in this field, this technique should be used in such a way as to accommodate relative misalignments in either direction, and may result in substantial extra ink usage--particularly for narrow image elements. 5. Overall Technique All of the provisions described above can be combined in a single print mode. This process results in a new algorithm for dividing each image element into two components printed in two passes respectively. An eight-by-seven image element or block 100 (FIG. 13) is used for a demonstration. For this example, the optimal line width is arbitrarily taken as two pixels horizontally and two pixels vertically. Preliminarily, the microprocessor firmware must analyze an image that is to be printed, to determine whether any such distinct image element or block 100 exists within the image--and, if so, to determine its boundaries. Such dissection requires scanning the overall image or parts of it for groupings of pixel columns or rows in excess of the optimal widths or heights, respectively, of edges. In principle this image-element identifying or sensing step may be performed to completion for the entire image before printing of any part of the image (or of any image-element block) begins, or may be performed for an entire image element before printing of any part of that element begins. Still another possibility is to perform the analysis on a progressive basis in which block-sensing continues while printing proceeds. The selection of one of these three basic approaches, or any other, should be made on the basis of tradeoffs between considerations including throughput (that is to say, overall printing speed) on the one hand, and memory capacity and firmware simplicity on the other. In any case the dissection or identification step preferably should stay ahead of the printing step by at least the number of pixel rows that is used as the optimal edge height. Next, two pieces of information are associated with each dot that makes up the eight-by-seven block 100-- a horizontal-portion label: outside right 112 (FIG. 13, central section), inside left 121, etc.; and a vertical-portion label: top 141 (FIG. 13, third section), bottom 142, or vertically middle 143. This allocational step too may be performed on a whole-image, image-element, or progressive basis. Then a simple algorithm is applied, using these two pieces of information to decide which dots should be printed in a first pass 131 (stippled dots, FIG. 14) and which in a second 132 ("X"-filled dots). The result of applying that algorithm to the blocks shown in FIG. 13 is shown in a first section, "Step 1", of FIG. 15; in principle either pass 131, 132 could be first and either could be second, but for definiteness one group of dots (stippled, 131) will be taken as first. One possible method of dot overlap is incorporated in the second section, "Step 2", of FIG. 15. Additional dots 134, 134' (downward-angled hatching) required for overlap are positioned along each of the interfaces between the two components 131, 132. As shown, the overlap dots 134, 134' may be placed along interior left edges or interior right edges, or some of each. In particular, for example, one group of overlap dots 134' is shown along the inward-facing left interior edge of the right-middle part of the first-pass dot block 131--that is to say, an edge that faces toward other dots of the same first-pass dot block 131. The remainder of the overlap dots, still only as an example, are all shown along outward-facing edges--that is to say, edges that face toward dots laid down in the opposite-direction pass. A depleted dot-overlap profile may be sufficient to mask undesired gaps. The third section, "Step 3", of FIG. 15 is the result of juxtaposing the two components of "Step 2", assuming an interscan alignment or placement error of about two-thirds of a pixel row. More specifically, the second-pass component 132 is drawn misplaced or displaced to the right relative to the first-pass component 131. This "Step 3" drawing has been assembled so that where overlap occurs the second-pass component 132--together with those of the overlap dots that are drawn in "Step 2" associated with the second-pass component 132--is on top of the first-pass component 131 and its associated overlap dots. Thus the previously discussed inward-facing dot row 134' of "Step 2" does not come into play, being completely covered by the two pixel columns of the inside-left block that is part of the second-pass group 132. That inward-facing dot row would actually be used only if the second-pass component 132 were displaced to the left. As can be seen from the "Step 3" composite--particularly near the left edge of the array--if the leading edges were defined as only one column wide (or if the line or image element were only two pixel columns wide) the spray or secondary dots due to the overlap dots 134 could project beyond the array boundary, once again degrading print quality. Hence the overlap-dot technique may be inappropriate for such cases. Inspection of "Step 3" also reveals that some overlap dots (those printed in the second pass 132) partly over-print dots that form the image proper (dots printed in the first pass); whereas other overlap dots (those printed in the first pass 131) partly underlie the image proper (dots printed in the second pass). In terms of resulting appearance this distinction is without consequence. In this overall print mode of FIG. 15, all edges printed are leading edges, each boundary is of optimal thickness, and there is minimal possibility of gaps. FIG. 16, upper right-hand view, is a resulting image printed on an inkjet printer--unmodified except for incorporation of this algorithm into the operating program. For comparison the remaining three views exhibit the same subject matter printed on the same printer but conventionally: unidirectional single-pass images, respectively right-to-left and left-to-right scans, in the two left-hand views; and a bidirectional two-pass image in the lower right-hand view. Thus the upper and lower left-hand images exhibit relatively severe blur at, respectively, the left and right sides of each vertical stroke; and that same severe degree of blur is seen at both sides of each stroke in the lower right-hand image. The upper right-hand image, by comparison is relatively much clearer or cleaner, at both sides of each vertical stroke. These samples were made using an inkjet printer of the Hewlett Packard Company, specifically a DeskJet Model 550c. The microprocessor in the DeskJet 500 family of printers has enough computing power to implement bidirectional, two-pass print modes described in this document; accordingly application of this invention is, at least in principle, not limited to new products but also available on a software-upgrade basis (e. g., with Windows® by merely transmitting a suitable printer driver to the printer) for use in any printers of that model family, or other model family with comparable or greater computing power. The foregoing disclosure is intended to be merely exemplary, and not to limit the scope of the invention--which is to be found by reference to the appended claims.
Inkjet-printed images (characters or graphics) have an image-quality asymmetry, correlated with the direction of pen scanning. The invention exploits this asymmetry to improve apparent overall quality by forcing the less-perfect side of each image element to become, and be hidden in, the element interior. To achieve this effect, part of each element is printed during pen scanning in one direction and part during scanning in an opposite direction. Neither scan prints the trailing edge--that is, the edge the pen reaches last, when moving in a given direction. Instead each scan prints only the leading edge--plus the interior or part of the interior, if the image is wide enough that its interior forms an analytically separate portion. If the image is wider still, it is subdivided so that one discrete interior portion is printed in the same scan with one of the lateral edges (the leading edge in one scan direction) and an additional discrete interior portion is printed in the same scan with the other lateral edge (the leading edge in the opposite scan direction). The widths of the "leading edge" and also of top and bottom edges are defined to optimize print quality by finding the best tradeoff between oppositely acting surface-tension effects: when very wide portions are printed all at once, creating a large pool of liquid ink, objectionable "runners" occur (which effect favors defining the "edges" as narrow); but when only very narrow portions are printed, edges objectionably reveal the pixel structure conspicuously (which favors defining the "edges" as wide). Overlap dots can be included in the portion or portions printed when scanning in either or both directions, to avoid narrow unprinted gaps in case of misalignment between scans in opposite directions.
Summarize the patent information, clearly outlining the technical challenges and proposed solutions.
[ "RELATED APPLICATIONS U.S. utility-patent application Ser.", "No. 08/055,660 of Gregory D. Raskin, filed on Apr. 30, 1993, and issued as U.S. Pat. No. 5,426,457 on Jun. 20, 1995, is relevant to certain aspects of the present invention as will be explained hereunder, and is hereby incorporated in its entirety into the present document.", "BACKGROUND 1.", "Field of the Invention This invention relates generally to inkjet printing systems in which an image (characters or graphics, or both) is constructed on a printing medium as an array of many individually computer-controlled inkdrops;", "and more particularly to a method for printing such an array which minimizes undesired artifacts that arise in the inkjet printing process.", "Related Art An inkjet image can be created through any one of myriad different inkjet nozzle firing patterns, implemented by specific program steps of a microprocessor.", "Such program steps are usually provided in the form of firmware for a general-purpose programmable microprocessor, but fixed arrays of electronic logic elements can be used instead.", "Any such firing pattern is called a "print mode".", "Print-mode variations encompass special uses of a pen or different portions of a pen in coordination with choice of printing-medium advance distance or frequency, special suppressions of firing for specified nozzles, and special choices of nozzle timing (as, for example, during scanning in different directions).", "Many different print modes are used to accomplish many different purposes.", "Such objectives include, for instance, high speed, or more accurate hue for specific printing media, or subtle reduction of the total amount of liquid ink present on a piece of print medium at one time, or (as in the Raskin patent document mentioned above) better alignment of forward and return scans in bidirectional printing, or masking of subtle printing defects--such as arise, for example, from cyclical variations or other imperfections in print-medium advance distance, or from isolated nonfiring nozzles, or from internozzle variations in ink volume.", "It is believed that heretofore all print modes known in the art have been devised on the implicit assumption that inkdrops, and (with respect to print quality) assemblages of inkdrops, are symmetrical.", "Thus it has been taken for granted that a drop deposited on a printing medium by a pen while scanning in one direction (for instance, from left to right) looks the same as a drop deposited by the same pen while scanning in the opposite direction (such as from right to left).", "Accordingly it has been implicitly assumed that inkdrop arrays deposited during scanning in different directions look the same--or, to put it in still another way, that image quality at both sides of a drop, or both sides of an assemblage of drops, is the same.", "If this were true, both sides of every image element would be equally good, or equally bad, so (given mutual alignment of image portions deposited during opposite-direction scans) it wouldn't matter which way the pen moved while printing different parts of each image element.", "It has been pointed out, however, that these implicit assumptions are false, or in other words that inkdrops or at least assemblages of them do indeed have good sides and bad sides.", "Careful inspection and study of inkjet-printed images reveals an image-quality asymmetry, correlated with the direction of pen scanning.", "Specifically, each distinct image element is cleaner on the side from which the pen moves toward that element than it is on the side toward which the pen moves from the same element.", "This difference appears to be due to a tendency of minute amounts of extremely fine spray, associated with firing of the pen, to overshoot the target position very slightly.", "Sometimes workers in this field refer to such spray as the "tail"", "of the inkdrop or as a "secondary dot".", "In any event it presents the appearance of a slight blurring, irregularity or dirtiness of the associated trailing part of what has been printed.", "Evidently this spray, tail or secondary dot results at least in part from lower average speed of fine particles in the direction normal to the printing medium, and therefore longer transit time between the nozzle and the medium.", "Such lower average speed may result from the processes that generate the spray, or possibly the effectively greater air damping for small particles, or both.", "(Even though damping force decreases with area, the effect of such drag is greater for small particles because mass and therefore momentum decrease with volume.", "Another possible contributor to offsetting of the spray is downwind drift of fine particles in the wake of the pen carriage.", "It will be understood that the utility of the present invention, to be described shortly, does not rest on the accuracy of any of these speculations.) After conventional bidirectional printing, the blurring effect is present at both sides of each image element, and so the original asymmetry of print quality for each element is concealed.", "After conventional unidirectional printing, the blur is present at only one side.", "Earlier thinking addressed to mitigating this print-quality defect may have concentrated on cocking or angling each nozzle to somehow align the tail or secondary dot with the main or primary dot.", "In any event in commercial practice this defect or at least part of it remains.", "Still other known print-quality defects have not been satisfactorily addressed in configuring print modes.", "In particular it is known that, when very wide continuous image areas are printed all at once, creating a large pool of liquid ink, undesired so-called "wicking"", "and "runners"", "occur;", "these are visible small streams of ink, representing paths of ink movement by capillarity through fibers of the printing medium and away from the area where the ink has been deposited.", "Heretofore print modes have addressed overinking problems either by (1) subtlely suppressing the total amount of ink on a printed image, or (2) allowing more drying time by dividing each image segment into checker-board-like subgroupings for printing in successive pen scans, the division being arbitrary--that is, without regard for the particular pattern or characteristics of image elements being printed.", "Both these techniques are ingenious, and they do ameliorate other overinking problems (such as offsetting, and adhesion of adjacent sheets) on which the present discussion does not focus, as well as misalignment between adjacent pen swaths;", "yet these techniques do have drawbacks.", "Suppressing the total amount of ink has some at least slight adverse effects on hue accuracy and color saturation.", "More importantly--since such ink reduction is willy-nilly, i. e. not correlated, with respect to image characteristics--overall ink suppression may unduly starve some image areas that actually are not subject to wicking.", "Dividing image segments for printing in three or more successive scans has the disadvantage of increasing the required printing time.", "It may do so needlessly in image areas free of wicking and runners.", "As noted above, wicking is most serious for broad expanses of continuous inking.", "On the other hand, when only very narrow portions are printed, edges objectionably reveal the pixel structure conspicuously as a distinct scalloped or serrated pattern, because surface tension is inadequate to pull the ink pool into a more-nearly straight border.", "Earlier print modes have not effectively addressed this problem.", "As will be apparent it tends--whenever present--to be exacerbated by the overall ink-suppression or multiscan image divisions discussed above.", "Another known print-quality impairment relevant to the present invention, and to other bidirectional printing systems, is misalignment between scans in opposite directions.", "This problem is manifested as a narrow line of unprinted or background color (for example white) where adjacent pixel blocks, printed in opposite-direction scans, fail to merge visually into a single apparent image element.", "The aforementioned Raskin patent document offers one valuable solution to such problems, though it depends for its full effectiveness upon good consistency of motor speeds in the reverse or retrace direction.", "That solution can evidently avoid narrow unprinted gaps where blocks of pixels laid down in opposite directions fail to be spaced properly at the regular pixel periodicity.", "It may not, however, cure a gap in which failure to visually merge results from inadequate wicking between the two blocks, due to one being already dry.", "A simpler solution to interscan misalignments, and one which may help to avoid this particular problem, could be useful.", "Heretofore these considerations have not been taken into account in devising print modes for best print quality.", "Thus important aspects of the technology used in the field of the invention are amenable to useful refinement.", "SUMMARY OF THE DISCLOSURE Part of the creative contribution of the present invention resides in the recognition that, since the implicit assumption of drop symmetry described above are in fact false, an additional degree of freedom is available for optimization of print quality.", "In fact print quality is subject to refinement and enhancement through print modes based on correcting that assumption;", "the present invention introduces such refinement.", "Before offering a relatively rigorous discussion of the present invention, some informal orientation will be provided here.", "It is to be understood that these first comments are not intended as a statement of the invention.", "They are simply in the nature of insights that will be helpful in comprehending the principles upon which the invention is based.", "The invention exploits the above-described asymmetry to improve apparent overall quality by forcing the less-perfect side of each image element to become, and to be hidden within, the interior of that image element.", "To achieve this effect, certain strategically selected parts of each element are printed during scanning of the pen in one direction and certain other parts during scanning in an opposite direction.", "Neither scan prints the trailing edge--that is, the edge the pen reaches last, when moving in a particular direction.", "Printing the trailing edge, as in conventional print modes, would allow the above-mentioned fine spray to be projected beyond that edge into what should be a background (for example, white) area free of the color being printed--thereby generating a very slightly dirty or blurry edge.", "Instead each scan prints only the leading edge--plus the interior or part of the interior, if the image is wide enough that its interior forms an analytically separate portion.", "If the image is wider still, it is subdivided and the subparts associated, for printing purposes, with the leading edges respectively.", "Thus one discrete interior portion is printed in the same scan with one of the lateral edges (the leading edge in one scan direction).", "An additional discrete interior portion is printed in the same scan with the other of the lateral edges (the leading edge in the opposite scan direction).", "In any event, during scanning in a first direction much of the previously mentioned fine spray that arises from printing of the leading edge and interior portion is deposited within the area that should be the trailing edge--and this area is filled in solidly at the beginning of the scan in a second or opposite direction, for which the area under discussion is a leading edge.", "Complementarily the fine spray from that scan is deposited within the area that is filled in solidly at the beginning of the first-direction scan.", "In short a large fraction of the fine spray is hidden within a solid field of ink of the same color.", "Such spray from the first-occurring scan is buried in a later solid edge formed in the second-occurring scan;", "and such spray from the second-occurring scan is imperceptible because it overprints the solid edge formed in the first.", "This discussion suggests that the width of a "leading edge"", "preferably is great enough to encompass all or most of the overshoot or drift distance of the spray.", "Attempting to thus capture all the spray, however, may be counterproductive in forcing use of leading-edge width to be larger than desirable with respect to other criteria.", "In particular, the width of a "leading edge"", "is best defined to optimize print quality by concealing most of the fine spray and also finding the best tradeoff between two oppositely acting surface-tension effects mentioned earlier: Objectionable wicking or runners appear when very wide portions are printed all at once, creating a large pool of liquid ink.", "This effect tends to favor defining the "edges"", "as narrow.", "Objectionable scalloped or serrated patterns appear when only very narrow portions are printed.", "This effect favors defining the "edges"", "as wide.", "Overlap dots can be included in the portion printed in either or both directions.", "Such dots avoid narrow unprinted gaps in case of misalignment between scans in opposite directions--and also in case of inadequate wicking to help merge adjacent blocks printed in different scans.", "Now with these preliminary observations in mind this discussion will proceed to a perhaps more-formal summary.", "The present invention has at least three main facets or aspects, which are amenable to practice independently of each other--although for best enjoyment of the benefits of the invention they are preferably used together.", "In preferred embodiments of all of these three major aspects, the present invention is a method of printing images as an array of many pixels, using a bidirectionally scanning inkjet pen.", "In a first of the three main aspects or facets, the method includes the step of--while scanning the pen in a first direction--printing the leading edge of an image element and refraining from printing the trailing edge of that element.", "The phrase "the leading edge"", "means the leading edge with respect to that first direction.", "More specifically yet, the leading edge "with respect to"", "a given scan direction is the edge which the moving pen reaches first when traveling in that direction (here, the stated "first direction").", "The method also includes the step of--while scanning the pen in a second direction opposite to the first direction--printing the leading edge of the same image element and refraining from printing the trailing edge of that element.", "Here "the leading edge"", "means the leading edge with respect to the second direction, which is to say the edge which the pen reaches first when traveling in the second direction.", "The foregoing may be a description or definition of the first major facet of the present invention in its broadest or most general terms.", "Even in such general or broad forms, however, as can now be seen the first facet of the invention refines and enhances the art of inkjet printing.", "In particular this new print mode tends to significantly enhance the image quality by concealing fine spray within the interior of each image element.", "Although the invention thus provides very significant advances relative to the prior art, nevertheless for greatest enjoyment of the benefits of the invention it is preferably practiced in conjunction with certain other features or characteristics which enhance its benefits.", "For example, it is preferred that the method further include the step of--while scanning the pen in the first direction--also printing at least one interior portion of the same image element.", "When the interior of an image element is large enough to be subdivided, preferably the interior portion is separated from the leading edge printed while scanning the pen in the first direction, and is substantially adjacent to the leading edge printed while scanning the pen in the second direction.", "This separation has the beneficial effect of avoiding the printing of overwide edges, and thereby avoiding generation of runners, mentioned earlier.", "In addition the method further includes the step of, while scanning the pen in the second direction, also printing at least one additional interior portion of the same image element.", "This additional interior portion is separated (for the same reason as just stated with respect to the first direction) from the leading edge printed while scanning the pen in the second direction, and is substantially adjacent to the leading edge printed while scanning the pen in the first direction.", "In such cases it is preferable too that the method include the step of--before printing either leading edge--analyzing the image element.", "Such analysis is used to determine which pixel columns are leading edges with respect to each scanning direction, which pixel columns are the first-mentioned interior portion, and which pixel columns are the additional interior portion.", "As suggested earlier the invention forces the trailing edge of each image element to become, and to be hidden within, the interior of that element.", "In abstract or philosophical effect each image element is folded inward upon itself to protect the viewer from relatively poorer-quality edges, like the rolled rough edges of a sheet-metal part that are hidden by a solid portion of the same part.", "As a practical matter, however, it may be more meaningful to say that each image element is strategically subdivided into subelements, and each of these subelements is printed in a way that is subject to the intrinsic asymmetry of print quality, and therefore is subject to print-quality defects--but the subelements are reassembled to form the starting, desired image element in such a way that solid portions of the subelements hide the defects.", "I have found that further significant image enhancement can be achieved by preferably also including a step of--before printing either leading edge--analyzing the image element to determine too which pixel rows are top edge, bottom edge, and vertically middle segment of each image element.", "In a related step, these top and bottom edge rows, above and below the previously mentioned "additional interior"", "portion, are associated with the leading edge and first-mentioned interior portion printed in the first direction, for printing during scanning in the first direction;", "and the top and bottom edge rows, above and below the first-mentioned interior portion, are associated with the leading edge and additional interior portion printed in the second direction, for printing during scanning in the second direction.", "In these preferred cases it is further preferable that the analyzing steps further include selecting the number of pixel columns to serve as leading edges in such a way as to optimize print quality;", "and also selecting the number of pixel rows to serve as top and bottom edges in such a way as to optimize print quality.", "More specifically the analyzing step preferably includes selecting the number of pixel columns to serve as leading edges in such a way as to obtain an optimum tradeoff between adverse effects of runners and adverse effects of surface tension.", "Methods in accordance with the first aspect of the invention preferably include performing the image-element analysis for all elements in the image--that is to say, before printing an image, analyzing the entire image to determine which pixel columns are leading edges of image elements within the image, with respect to each scanning direction.", "In preferred embodiments of a second of its main facets or aspects the method of the invention includes the steps of: while scanning the pen from left to right, printing the left edge of an image element and refraining from printing the right edge of that element;", "and while scanning the pen from right to left, printing the right edge of the same image element and refraining from printing the left edge of that element.", "In preferred embodiments of a third of its main facets the method includes the step of analyzing an image element to determine which pixel rows should be treated as the top edge, bottom edge, and vertically middle part, respectively, of the element;", "and to determine which pixel columns should be treated as the left and right edges, and first and second interior portions, respectively, of the element.", "In this third facet the analyzing step includes selecting the number of rows to treat as top and bottom edges in such a way as to optimize image quality.", "The method also includes the steps of: while scanning the pen in one direction, printing the top and bottom edges above and below the first interior portion;", "and while scanning the pen in a second, opposite, direction, printing the top and bottom edges above and below the second interior portion.", "All of the foregoing operational principles and advantages of the present invention will be more fully appreciated upon consideration of the following detailed description, with reference to the appended drawings, of which: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a very schematic diagram showing in isometric or perspective view what is meant by "leading edge"", "and "trailing edge"", "in an inkjet printing context for pen movement from left to right;", "FIG. 2 is a like view for pen movement from right to left;", "FIG. 3 is a reproduction of a photographic record, greatly enlarged, of a narrow vertical line printed on an inkjet printer;", "FIG. 4 is a view like FIGS. 1 and 2 showing one step of a print-mode method according to the present invention;", "FIG. 5 is a like view showing a later step of the same print-mode method;", "FIG. 6 is an idealized illustration of a relationship between line thickness and edge quality--showing in particular the effects of surface-tension smoothing and runners;", "FIG. 7 is a diagram of the same relationship in a somewhat more quantified form;", "FIG. 8 is a schematic representation of simplified pixel-wise division of a horizontal line into outside edges and a single interior portion in accordance with the present invention;", "FIG. 9 is a like representation of simplified division of a horizontal line into outside edges and two interior portions, also in accordance with the invention;", "FIG. 10 is a like representation of a two-dimensional image element printed in two passes, using the FIG. 9 division;", "FIG. 11 is a like representation of simplified division of a vertical line into top, bottom and vertically middle portions;", "FIG. 12 is a like representation of the use of an overlap dot to prevent image defects due to interscan misalignments;", "FIG. 13 is a view like FIG. 10 but showing preliminarily how the simplified horizontal-division method of FIG. 9 is integrated with the simplified vertical-division method of FIG. 11, in printing a single image element;", "FIG. 14 is a related view showing an algorithm for operating on the FIG. 13 blocks;", "FIG. 15 is a three-step progressive view like FIG. 10 but showing how the integrated but preliminary scheme of FIGS. 13 and 14 is carried on to complete implementation;", "and FIG. 16 is a photographic reproduction of four greatly enlarged photographic records of a word printed on an inkjet printer, contrasting performance of the print mode of the invention with three conventional print modes.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 1.", "Trailing and Leading Edges As used in this document, the terms leading edge and trailing edge are determined by the scan direction of the printer carriage.", ""Leading edge"", "designates the first edge of the vertical line printed, and "trailing edge"", "refers to the last edge printed.", "FIG. 1 shows in three successive subviews the printing of a vertical line 1, 2 two pixels wide onto a sheet 52 of paper or other printing medium, when the pen 51 is scanning 53, 55 from left to right, and identifies the associated leading edge 1 and trailing edge 2.", "In the first (left-hand) subview, during its rightward scanning motion 53 the pen 51 ejects a first column of inkdrops 54.", "In the second (center) subview those drops are seen to have formed on the print-medium sheet 52 a column 1 of pixels--this will be the so-called "leading edge"", "of the finished line.", "To the right of each dot in the first column 1 there has been drawn, in this second subview of FIG. 1, a narrow rightward protuberance or extension 3.", "This tail-like extension 3 symbolizes the so-called "secondary dot"", "mentioned earlier, and will be discussed in some detail shortly.", "Also in this second subview, the pen 51, while continuing to move 55 in the same direction, is seen to be ejecting a second column of drops 56.", "In the third (right-hand) subview the pen 51 has completed its scan, and the second column of drops is seen to have formed on the sheet 52 another column 2 of pixels--the so-called "trailing edge"", "of the finished line.", "Here the leading edge 1 is the left side of the line and the trailing edge 2 is the right side.", "In this view the protrusions from the first column 1 of dots, however, are no longer visible: they have been buried in the more massive ink deposit of the second column 2.", "Each of the dots 2 in the second column, however, has been drawn with a rightward tail-like protrusion 3 similar to those of the first column.", "Thus no matter how many pixel columns are aggregated in this fashion the rightmost column is accompanied by a column of secondary dots that are visible.", "A more accurate, photographic representation of this disturbance appears in FIG. 3, which demonstrates a typical difference between the leading- and trailing-edge quality of a printed line.", "As seen in FIG. 3, the leading edge 1 more closely approximates a straight line.", "The sharpness of the trailing edge 2 is irregular 3 due both to edge roughness and to increased amount of spray;", "the overall result is that the print quality of the leading edge 1 is superior to that of the trailing edge 2.", "FIG. 2 shows phenomena analogous to those of FIG. 1, for printing of a like line 1', 2'", "when the pen 51 is moving 63 from right to left.", "The first subview (in this case the right-hand subview) portrays the pen 51 moving 63 leftward and ejecting a first column 64 of drops.", "These drops in the second (central) subview are seen to have formed on the sheet 52 a first column 1'", "of pixels--the "leading edge"", "in this leftward scan--together with an associated column 3'", "of secondary dots, which in this case are leftward from the column 1'", "of primary dots rather than rightward as in FIG. 1. The second subview also shows a second column 66 of drops being ejected while the pen 51 continues its leftward scan 65.", "The third subview in FIG. 2 shows the resulting two-pixel-wide line on the sheet 52 after the pen 51 has completed its scan--namely, the leading edge 1'", "on the right and trailing edge 2'", "on the left.", "Once again the first column of secondary dots has been buried in the second column 2'", "of primary dots, but in this third subview a new array of secondary dots 3'", "has been created--still leftward from the associated primary pixel column 2'.", "FIGS. 1 and 2 demonstrate that: the leading edge 1, 1'", "can be at either the right or left side of the printed vertical line, depending on the direction 53/55, 63/65 respectively in which the pen 51 moves;", "and an irregularity, symbolized in these drawings by the tail-like secondary dots 3, 3', always appears at the trailing edge 2, 2'", "of any unidirectionally printed inkjet image.", "It can be appreciated from this presentation that like irregularities 3, 3'", "appear as well at both edges of any inkjet image printed bidirectionally, if such an image is printed using a conventional print mode known heretofore.", "It will be understood that these drawings are only examples.", "Analogous identifications of leading and trailing edges can be established for systems in which pen scanning occurs along axes other than the horizontal--whether vertical or oriented at arbitrary angles.", "Since leading edges 1 are superior to trailing edges 2, it is desirable that all vertical edges printed be leading.", "This can be accomplished by using a bidirectional print mode as described below for a like two-pixel-wide line.", "As the pen carriage moves 73 from left to right (FIG.", "4), the pen 51 ejects inkdrops 74 to create a first column 1 of dots (pixels), which will constitute a leading edge of the finished line.", "In FIG. 4 as in FIGS. 1 and 2, the roughness on the trailing side of this pixel column 1 has been incorporated into the illustration, symbolized by a rightward extension or elongation 3, corresponding to the irregularities 3 of FIG. 3. The direction of pen-carriage scanning is then reversed (FIG.", "5).", "While the pen scans leftward it ejects a second column 84 of drops to make a second column 1'", "of dots on the sheet 52.", "Thus both edges 1, 1'", "of the resulting vertical line are leading edges.", "The second column 1'", "of dots, however, now buries the secondary dots 3 associated with the first column 1 of dots--and the secondary dots 3'", "created in the process of generating the second column 1'", "overprints the first column 1 of like-color dots.", "As a result of this strategic superposition, neither column of secondary dots can be seen.", "This advantageous result will obtain regardless of the number of adjacent columns aggregated, provided only that one or two dot columns along each edge are printed while the pen scans into the aggregation of columns from the adjacent unprinted or background area.", "(In some extreme cases the irregularity or secondary-dot phenomenon may extend over more than one pixel width.", "For such cases, for vertical lines more than three columns wide, it is desirable that the dots printed as the "leading edge"", "consist of two pixel columns rather than just one.) 2.", "Line Width The quality of a vertical-line edge depends on the line thickness, or width--the number of dot/pixel columns that make up the line.", "In a vertical line 13 (FIG.", "6) only one dot wide, there is often not enough ink for the surface tension to smooth out the vertical edges;", "therefore these exhibit a marked scalloping effect 4, a series of pronounced inward-pointing cusps.", "As more ink is laid down--for instance in a two-column-wide line 14--the vertical edges 5 become somewhat smoother but perhaps not entirely straight.", "As the width of the line continues to grow, perhaps to a three-column line 15, the vertical edges may be much more nearly straight, but another effect becomes noticeable: The amount of ink laid down begins to be excessive, and the extra ink starts to move by capillarity--or "wick"--into the paper fibers, causing visible runners 7 to extend or "feather"", "outward from the edges.", "The extent of both edge smoothness and feathering 7 depends strongly on the ink formulation and type of printing medium in use;", "however, as a general matter while the number of columns solidly printed continues to increase (as exemplified at 16 in FIG. 6) eventually the edges 8 become quite straight but the number and length of runners 9 worsen severely.", "To integrate these observations, the important trends observed with increase of the number of pixel columns are (1) edge smoothing 8 and (2) feathering 7, 9.", "FIG. 7 shows how the two trends can be optimized in a quasi quantitative sense.", "In FIG. 7 the PQ ("print quality") scale from "good"", "to "bad"", "quantifies on a common, standardized basis the visual perception of both runners 107/109 and surface-tension smoothing 108, using as a PQ measure the areal deviation per unit length of line.", "The areal deviation is the printed area that extends beyond a smoothed, average-position edge (in this case rectilinear).", "Thus an ideal or "good"", "edge has PQ=0 (as it too, for this case, is rectilinear).", "The PQ sum or aggregate 110 goes through a minimum, which is an optimum point 110 for the particular combination of printing medium and ink formulation in use.", "With respect to horizontal lines, a further distinction is useful: the distinction is between the boundary 10, 10'", "(FIG.", "8) and interior 20 of the line.", "The boundary of a horizontal line is, or boundaries are, the first and last dot segments 10, 10'", "that compose the line.", "For optimal results either or each boundary may consist of two or more dots.", "For instance two dots are shown as making up only the left-hand portion of the boundary 10 in the first subview of FIG. 8, but both left- and right-hand portions of the boundary 10'", "in the third subview.", "One can divide the horizontal line even further into a right-side component and a left-side one.", "This results in four sections (FIG.", "9) for each horizontal line: left end or edge 11, right edge 12, left interior portion 21 and right interior portion 22.", "Integration of Leading-Edge, Optimum-Width and Element-Subdivision Concepts Integration of the above concepts results in an optimized print mode.", "The three concepts to be integrated are: two-pass, bidirectional, leading-edge-only printing;", "optimal line width;", "and the four horizontal-line subdivisions.", "To print an image element (a representation of an object, an alphanumeric character, etc.) in a two-pass mode requires dividing the element into two main components, one to be printed on each pass, such that when the two components are together on the printing medium the original image element appears.", "A further criterion for this print mode is that, when possible, both the right and left boundary thicknesses are optimized.", "To construct of the two main components, the interior of the image element is divided into two portions and each portion paired with its opposite boundary.", "For example a left inside portion 21 (FIG.", "10) is part of the same main component as--and is printed in the same pass 31 with--the right boundary or edge 12;", "and the right inside portion 22 is part of the same main component as, and printed in the same pass 32 with, the left edge 11.", "In FIG. 10 all of the stippled dots 31 make up the material printed in one pass (for instance a first pass), and all of the "X"-filled dots 32 make up the material printed in another pass (for instance a second pass).", "As will be seen shortly, FIG. 10 represents a simplified special case of applying a more general algorithm;", "the illustrated print mode is the simplest expression of the three concepts listed at the beginning of this section.", "A root understanding is that print quality is dependent on the order and method by which dots are placed on the page.", "Overlap Pixels, and Vertical Divisions To further refine the optimization, one can find the optimal boundary thickness for both horizontal and vertical lines.", "This suggests that even a narrow (e.g., one-pixel wide) vertical line should be split into three parts--top 41 (FIG.", "11), bottom 42, and vertically middle 43.", "In this part of the process it should not be assumed that the same thickness is optimal for both directions.", "Directionality of paper grain, for instance, could have an influence on the extent of surface-tension effects.", "When two dot groups 31a, 32a (FIG.", "12) placed by pen scans in two opposite directions, respectively, are mutually well aligned, the groups are spaced apart horizontally by the same spacing as pixel columns within each group.", "The result, as in the right side of the first (top) subview of FIG. 12, is that the groups 31a, 32a merge to look like a continuous horizontal line--or, in a taller image element (e.", "g., wide vertical line), a continuous field.", "In case of imperfections in dot-placement accuracy of the printing system, particularly interscan misalignments as between opposite-direction pen scans, another refinement may be needed.", "One effect of such misalignment can be a small displacement 33b between the groups of dots, as seen at left in the second (center) subview of FIG. 12.", "Such misalignment results (right side of second subview) in interruption of the finished composite image element by a narrow white (or other background-color) gap 33--or vertical stripe 33, for a taller image element.", "For elements just two pixels wide (not shown in FIG. 12) the only solution may be to improve interscan tolerances.", "One particularly effective way of doing so is set forth in the previously mentioned Gregory D. Raskin co-pending patent document, incorporated by reference into this document.", "The Raskin technique can be used for the case of wider lines as well, and for both cases should substantially eliminate the objectionable stripe 33.", "For wider lines, however, another solution is to guarantee overlap of adjoining segments as by providing an additional overlap dot 34 (third subview in FIG. 12).", "As will be understood by people skilled in this field, this technique should be used in such a way as to accommodate relative misalignments in either direction, and may result in substantial extra ink usage--particularly for narrow image elements.", "Overall Technique All of the provisions described above can be combined in a single print mode.", "This process results in a new algorithm for dividing each image element into two components printed in two passes respectively.", "An eight-by-seven image element or block 100 (FIG.", "13) is used for a demonstration.", "For this example, the optimal line width is arbitrarily taken as two pixels horizontally and two pixels vertically.", "Preliminarily, the microprocessor firmware must analyze an image that is to be printed, to determine whether any such distinct image element or block 100 exists within the image--and, if so, to determine its boundaries.", "Such dissection requires scanning the overall image or parts of it for groupings of pixel columns or rows in excess of the optimal widths or heights, respectively, of edges.", "In principle this image-element identifying or sensing step may be performed to completion for the entire image before printing of any part of the image (or of any image-element block) begins, or may be performed for an entire image element before printing of any part of that element begins.", "Still another possibility is to perform the analysis on a progressive basis in which block-sensing continues while printing proceeds.", "The selection of one of these three basic approaches, or any other, should be made on the basis of tradeoffs between considerations including throughput (that is to say, overall printing speed) on the one hand, and memory capacity and firmware simplicity on the other.", "In any case the dissection or identification step preferably should stay ahead of the printing step by at least the number of pixel rows that is used as the optimal edge height.", "Next, two pieces of information are associated with each dot that makes up the eight-by-seven block 100-- a horizontal-portion label: outside right 112 (FIG.", "13, central section), inside left 121, etc.", "and a vertical-portion label: top 141 (FIG.", "13, third section), bottom 142, or vertically middle 143.", "This allocational step too may be performed on a whole-image, image-element, or progressive basis.", "Then a simple algorithm is applied, using these two pieces of information to decide which dots should be printed in a first pass 131 (stippled dots, FIG. 14) and which in a second 132 ("X"-filled dots).", "The result of applying that algorithm to the blocks shown in FIG. 13 is shown in a first section, "Step 1", of FIG. 15;", "in principle either pass 131, 132 could be first and either could be second, but for definiteness one group of dots (stippled, 131) will be taken as first.", "One possible method of dot overlap is incorporated in the second section, "Step 2", of FIG. 15.", "Additional dots 134, 134'", "(downward-angled hatching) required for overlap are positioned along each of the interfaces between the two components 131, 132.", "As shown, the overlap dots 134, 134'", "may be placed along interior left edges or interior right edges, or some of each.", "In particular, for example, one group of overlap dots 134'", "is shown along the inward-facing left interior edge of the right-middle part of the first-pass dot block 131--that is to say, an edge that faces toward other dots of the same first-pass dot block 131.", "The remainder of the overlap dots, still only as an example, are all shown along outward-facing edges--that is to say, edges that face toward dots laid down in the opposite-direction pass.", "A depleted dot-overlap profile may be sufficient to mask undesired gaps.", "The third section, "Step 3", of FIG. 15 is the result of juxtaposing the two components of "Step 2", assuming an interscan alignment or placement error of about two-thirds of a pixel row.", "More specifically, the second-pass component 132 is drawn misplaced or displaced to the right relative to the first-pass component 131.", "This "Step 3"", "drawing has been assembled so that where overlap occurs the second-pass component 132--together with those of the overlap dots that are drawn in "Step 2"", "associated with the second-pass component 132--is on top of the first-pass component 131 and its associated overlap dots.", "Thus the previously discussed inward-facing dot row 134'", "of "Step 2"", "does not come into play, being completely covered by the two pixel columns of the inside-left block that is part of the second-pass group 132.", "That inward-facing dot row would actually be used only if the second-pass component 132 were displaced to the left.", "As can be seen from the "Step 3"", "composite--particularly near the left edge of the array--if the leading edges were defined as only one column wide (or if the line or image element were only two pixel columns wide) the spray or secondary dots due to the overlap dots 134 could project beyond the array boundary, once again degrading print quality.", "Hence the overlap-dot technique may be inappropriate for such cases.", "Inspection of "Step 3"", "also reveals that some overlap dots (those printed in the second pass 132) partly over-print dots that form the image proper (dots printed in the first pass);", "whereas other overlap dots (those printed in the first pass 131) partly underlie the image proper (dots printed in the second pass).", "In terms of resulting appearance this distinction is without consequence.", "In this overall print mode of FIG. 15, all edges printed are leading edges, each boundary is of optimal thickness, and there is minimal possibility of gaps.", "FIG. 16, upper right-hand view, is a resulting image printed on an inkjet printer--unmodified except for incorporation of this algorithm into the operating program.", "For comparison the remaining three views exhibit the same subject matter printed on the same printer but conventionally: unidirectional single-pass images, respectively right-to-left and left-to-right scans, in the two left-hand views;", "and a bidirectional two-pass image in the lower right-hand view.", "Thus the upper and lower left-hand images exhibit relatively severe blur at, respectively, the left and right sides of each vertical stroke;", "and that same severe degree of blur is seen at both sides of each stroke in the lower right-hand image.", "The upper right-hand image, by comparison is relatively much clearer or cleaner, at both sides of each vertical stroke.", "These samples were made using an inkjet printer of the Hewlett Packard Company, specifically a DeskJet Model 550c.", "The microprocessor in the DeskJet 500 family of printers has enough computing power to implement bidirectional, two-pass print modes described in this document;", "accordingly application of this invention is, at least in principle, not limited to new products but also available on a software-upgrade basis (e.", "g., with Windows® by merely transmitting a suitable printer driver to the printer) for use in any printers of that model family, or other model family with comparable or greater computing power.", "The foregoing disclosure is intended to be merely exemplary, and not to limit the scope of the invention--which is to be found by reference to the appended claims." ]
FIELD OF THE INVENTION This invention relates generally to subway systems for mass transit of passengers in cities and more particularly concerns a subway passenger loading and unloading control system that minimizes subway overcrowding and renders the subway passenger handling system more efficient. BACKGROUND OF THE INVENTION This invention is described herein particularly as it relates to subway train systems and passenger control therefor. It is to be understood, however, that this invention has efficient application in any facility where passenger control is desired and therefore the example herein should not be limiting of the scope of this invention. It is well known that a subway is one of the most efficient passenger transportation systems in a large city. However, most of the subways in the world are confronted with a traffic congestion problem during rush hours. This congestion is mainly caused by over-loading of passengers into the subway which exceeds the limits of transportation capacity of the system. Train travel time delays and over crowding of subway train compartments during rush hours are a direct result of this over-loading. Two of the most important factors which govern the capacity of a subway transportation system are the subway train travel time from the station of origin to terminus and the maximum number of subway trains dispatchable during rush hours. The total travel time (TOT) of a subway train from the station of origin to terminus is generally composed of three time elements: 1) the sum of subway train interval travel time between two adjacent stations; 2) the sum of passenger unloading and loading time at each station; and 3) the sum of extra waiting time in a station due to some uncontrollable circumstances. The maximum number of subway trains dispatchable (MTD) for a given time duration depends on TOT and the minimum distance on time interval allowed between two consecutive subway trains (MIT). It is obvious that the more subway trains that are dispatched, the more people can be transported but it is practically limited by the MTD. Since the MIT is more or less a fixed quantity for a given subway system for safety reasons and particularly it reaches to the limit during the rush hours, further reduction of the MIT is very unlikely. Thus it appears that the only viable option to increase a subway system's transportation capacity is to maximize the MTD by minimizing the TOT if we are constrained to utilize currently existing subway trains without any costly major remodifications to the subway system. In order to minimize the TOT of subway systems, all three time elements of the TOT should be minimized: 1) Interval Travel Time (ITT) Since the maximum speed of a subway train is limited, the minimum ITT exists for each station interval. The minimum subway train run time can be defined as the sum of minimum ITT and this quantity is a constant and can be attained in an ideal situation only. The real value of ITT during rush hours is very likely greater than the minimum ITT due to the slow down of a subway train caused by the loading and unloading delay of preceding subway trains. In order to minimize extra ITT delay, it is necessary to implement a method which will force each subway train to keep a preset or preprogrammed station stop time for each station without any exceptions. 2) Passenger Loading and Unloading Time (PLT) This is the most critical time element within the TOT which increases the most during rush hours; and, effective reduction of PLT is the key for minimization of the TOT. Currently, a significant increase of PLT during rush hours is mostly caused by over-crowding of passengers and the lack of an efficient passenger loading control system in the existing subway train system. Most currently existing subway trains employ a two-door design. Each door is being utilized for both passenger loading and unloading so that the passenger flow through the door is bi-directional. It appears that the PLT for a bi-directional door system is almost twice that of the mono-directional door system which allows passengers to get in through an "Entrance Only" door and get out through an "Exit Only" door. (For example, a street car with three doors, two end doors assigned for "Entrance Only" and the middle for "Exit Only"). This is because in the bi-directional door system passenger loading can only begin after the passenger unloading is completed, while for the mono-directional door system, the unloading and loading process can be done concurrently. The bi-directional door system has further problems under a crowded environment during rush hours. Usually, passengers inside of the subway train who stand near the exit door and passengers on the platform ready to get on the subway typically block the accessway for passengers who wish to get off and this further delays the passenger unloading process. On the other hand, for mono-directional door systems, the flow of passengers within a subway train compartment is mono-directional (entrance to exit) and no passenger on the platform will block the exit door thus, the unloading process will be more efficient than a bi-directional door system. 3) Extra Waiting Time It appears that most of the subway train extra waiting time during rush hours is caused by the over crowding of passengers at several bottle neck subway stations. For example, at these bottleneck stations, some passengers try to get on already crowded subway trains and hang on near the door. This prevents the closing of subway train doors and causes further delay of departure of the subway train. Currently, subway operators of several large cities (Tokyo, Seoul, etc.), solve this problem by assigning passenger pushers to push passengers into the subway car compartment in order to close the door. In order to solve rush hour subway traffic congestion problems, it is most desirable to implement a subway passenger loading control system which will accomplish the following: 1) Minimize passenger loading and unloading time. 2) Prevent over loading of passengers at each station for all subway trains at all times. 3) Make all subway trains maintain a preprogrammed stop time at each station. This invention utilizes a computerized subway passenger loading and unloading monitoring system which is installed at each entrance and exit area as well as in the interior of subway train compartments. This enables us to keep track of the number of passengers entering and leaving the subway train as well as the flow of passengers inside of the subway train. By knowing this vital passenger flow information within the entire subway system, it is possible to accomplish the passenger control system objectives described above. BRIEF DESCRIPTION OF THE DRAWINGS So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be understood by reference to the embodiments thereof which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. IN THE DRAWINGS FIG. 1 is a front view of a subway train stopped at the subway station platform showing the gates opened and the process of passenger loading/unloading in progress. FIG. 2 is a detailed sketch of a subway train entrance gate where boarding passengers are entering the gate through pairs of passing passenger sensing posts. FIG. 3 is a top view of a subway train car compartment after removing the roof to show the partitioning of the interior area of the subway train compartment into three functional zones namely; entrance zone, seat zone, and exit zone. FIG. 4 is a detailed view of the boundary between the entrance zone and the seat zone. FIG. 5 is a perspective view of the passenger loading area fence system which might be used only for the congested subway station where very strict passenger loading control is needed. FIG. 6 is a top view of a two-gate subway train car compartment after removing the roof to show the arrangement of passing passenger sensor system and passenger loading system. FIG. 7 is a view of the two-way passing passenger sensing post. FIG. 8 is perspective view of the passenger loading area fence system for the two-gate subway train. FIG. 9 is a top view of a conventional two-gate subway train without any sensor posts. FIG. 10 is a perspective view of the passenger load area fence with the passing passenger sensing posts on the platform. FIG. 11 is a front elevational view of a passenger control gate constructed in accordance with the present invention and being provided with a multiple sensor system for passenger detection. FIG. 12 is a side elevational view of the multiple sensor passenger detection gate of FIG. 11. FIG. 13 is a plan view of the multiple sensor passenger detection gate of FIGS. 11 and 12, illustrating the presence of passengers in relation to the gate. FIG. 14 is a graphical representation of sequentially numbered sensors for a subway passenger control facility that functions according to the present invention. FIG. 15 is a graphical representation of a time series being the simple sum of a number of timed series relating to passenger separation in the passenger control system. FIG. 16 is a graphical representation of the summed sensor time series which is likely to occur during rush hours. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, two subway train cars 1 and 2 are connected by a subway train coupling 3. The subway train is stopped along the subway station platform 4 and an electrical passenger loading information display panel (or TV monitor) 6 is suspended from the station platform ceiling 5. Three passing passenger sensing (PPS) posts 9 are installed at the subway train entrance gate 7 and two boarding passengers are shown to be entering the subway train by passing between a pair of PPS posts 9 which will be used for counting the number of passengers entering into the subway train through this entrance. At the centrally located exit gate 8, five PPS posts 9 are installed and four deboarding passengers 10 are shown to be exiting the subway train parallel by passing between pairs of PPS posts 9 which serve for counting the number of passengers deboarding the subway train through this gate. Passenger loading traffic control signal 17 which is controlled by a computer installed in the subway train, has green and red lights; the green light signaling "Enter", and the red light signaling "Do Not Enter". The red light will be illuminated either when the number of passengers on board equals or exceeds the maximum capacity of the subway train compartment or a few seconds prior to the closing of the entrance gate in order to warn boarding passengers to stay on the platform so that the door can be closed without blocking. With reference to FIG. 2, the entrance gate 7 of the subway train is shown in detail. Infrared beam transmitters 11 and 13 and their respective beam receivers 12 and 14 are attached to the PPS posts 9 so that the entering passengers 15 will block the beam when they pass between the transmitter and receiver pairs. Each blocking will be counted as one passenger passing and thus count will be transmitted to the on-board computer to be described in detail hereinbelow. FIG. 3 is a plan view of the interior of a typical subway train compartment which shows a passenger movement monitoring sensor system to monitor the movement of passengers inside the subway train compartment. The subway train 1 is located on rails 21 which are supported in conventional manner by railroad ties 20. The subway car is shown to be stopped adjacent the passenger platform 4. All PPS posts installed on the platform side of the subway train gates are identified by reference numerals 9 and all PPS posts installed in the subway train gates in the opposite side of the passenger platform are depicted by reference numerals 16. The interior space of the subway train 1 is functionally divided into three zones by the sensor system. The front and rear entrance zones 41 and 42 are defined as an area combined by the PPS posts in the front and rear of the subway car 16, 25, 26, 27, 29, 30, 31 and 9. The passenger compartment includes front and rear passenger sitting zones 45 and 46 which are respectively defined by PPS posts 25, 26, 27, 29, 30, 31, 35, 37, and 33. The platform side and the opposite side of the platform exit zones 44 and 43 are respectively defined by PPS posts 9, 35, 37, 38, 37, and 34 and by PPS posts 16, 33, 37, 38, 37, and 34. Among the three zones, the entrance and exit zones are designated for standing passengers only, while there are seats in the passenger sitting zones 45 and 46. The sitting zone fence 34 is a barrier between the sitting and exit zones which has the purpose of causing passengers to move through the passenger sensors placed in between these two zones. The boundary between the entrance and the sitting zones is defined by an array of PPS posts 25, 26, 27, 29, 30 and 31. On the passenger platform, the passenger loading area located in front of the subway train entrance 7 is marked with a pair of solid lines 47 and a dotted line 48 for waiting passengers to line up. For some heavy traffic subway stations, the passenger loading area may need to be designated by a loading area fence 50 and gates 51. A prospective view of this fence diagram is depicted in FIG. 5 and will be described in detail hereinbelow. It should be pointed out that all sensors are connected with well shielded wires to the subway train compartment mini-computer 39. A computer 39 on each subway train car is linked to the subway train passenger monitoring computer 40 located in the subway train operators compartment (as shown in FIG. 6). While the subway train is traveling through the underground tunnel of the subway system, the subway train passenger monitoring computer 40 will continuously transfer information pertaining to the change of passenger distribution within each subway train compartment to a station computer 42 at the next passenger station or passenger loading and unloading platform wirelessly using cellular technology or other suitable means. All information received by the subway train station computer will be instantly relayed to a central passenger monitoring and control computer 47 by conventional means for further data processing. The elevational view of FIG. 4 shows the boundary between the entrance zone 41 and the sitting zone 45 in detail. The platform side PPS posts 31, 30, and 29 are blocked by a rotating cross bar 32 which has a hinge point 17 at one end thereof. The cross bar rests on top of the partitioning fence 28 with the hinge point being located in the middle of the fence 28. The opposite side platform PPS posts 25, 26, 27 are open to admit passengers moving into the exiting zone. These sensors will monitor the number of passengers moving from the entrance zone 41 to the sitting zone 45. Location of the entrance to sitting zone passage at the opposite side of this platform entrance is most important for the full utilization of spaces in the entrance zone. Further, the passenger entrance zone is in essence a passenger loading buffer for the sitting zone. If the passage between these two zones is placed in the middle, one half of the entrance zone which is the opposite side of the platform will become a dead space from the standpoint of passenger utilization and its space will therefore be wasted. A passenger dead space of this nature could be equivalent to reducing the length of loading area for the sitting zone by one half and thus should not be tolerated in passenger compartment design. FIG. 5 is a perspective view of a passenger loading area protection fence system which is located on the loading platform as shown in FIG. 3. If all passengers entering the entrance 7 of the subway train obey the rules of passenger courtesy and do not try to enter the subway car when the red light 17 is illuminated, this fence is not needed. A loading zone fence 50 and rotating gate 51 which are similar to the ones used in the subway station entrance, completely surrounds the loading zone. The gate 51 has an electronic passenger counting mechanism which is connected to the subway station computer and will physically limit the number of passenger entering to the loading zone at the passenger loading platform under the control of signals generated by the subway station computer. To prevent over-crowding of the subway train, it is necessary to control the number of passengers on board within the limit of the maximum passenger capacity for all subway train compartments. The total number of passengers on board a subway train compartment at any given time is simply the difference between the total number of passengers on-boarded through the entrance gates 7 and off-boarded through the exit gate 8. During rush hours, the subway train will be fully loaded beginning at some station away from the station of origin. Fully loaded implies that the number of passengers on board equals the designated capacity of the subway train compartment, but still there may be room available so that passengers can move around without too much difficulty. As soon as a fully loaded subway train closes all of its entry and exit gates and is ready for departure, an announcement will be made to request that passengers who will be deboarding at the next station move to the exit area (exit zone 44) which is most likely to be the least crowded at the time of departure due to unloading of passengers from this area at the current station. As passengers move from the sitting zones 45 and 46, to the exit zone 44, some vacant space (room) will occur in the sitting zone and this will allow passengers in the entrance zones 41 and 42 to move into the sitting zone 45 and 46 respectively. Since passengers go through the spaces between PPS posts 25, 26 and 27, the number of passengers moving from the entrance zones to the sitting zones is known. Thus the exact number of passengers remaining in the entrance zone is known as well. If some passengers remain in the entrance zones who should have moved to the sitting zones, the computer 39 will activate the speaker system in the entrance zones calling and requesting the passengers in the entrance areas move into the interior of the subway train to make room for passengers to be loaded in the next station. As passengers respond to this request, more passengers in the entrance zones will move into the sitting zone resulting in more passenger space availability in the entrance zones. The change of passenger distribution within the entrance zones 45 and 46, and in the exit zones 43 and 44 will be continuously transferred to the computer at the next station, while the subway train is traveling to the next station. Utilizing the detailed passenger distribution information which is transferred from the computer on the moving subway train to the computer in the next station together with the preprogrammed stop time at the station, the computer at the central control facility will determine the optimum number of passengers that will be permitted to load in each subway car entrance. It should be pointed out that the preprogrammed station stop time at each station should be strictly kept in order for all subway trains to operate on time as scheduled. Thus, the maximum number of passengers to be loaded will be limited to the number of passengers that can be loaded during the preprogrammed station stop time even if there are extra spaces available. Sometimes, it is possible that the central computer will command the unloading of passengers only and will not permit the loading of any passengers at less crowded stations, even if there is plenty of room available in the subway train compartment, in order to pick up more passengers (to ease an overcrowding problem) at a bottle neck station. In this way, overcrowding at a bottle neck station can be spread out to several less crowded stations. Once the optimum passenger loading decision is made, this information will be transmitted from the computer in the central passenger control facility to the computer in next station and this will be displayed on electronic passenger vacancy display 6 at the passenger platform prior to the arrival of the subway train. This feature will enable passengers to adjust their schedules or mode of travel in compliance with the condition of the subway system. Displaying passenger vacancy information at each passenger entrance at the station prior to the arrival of the subway train is very important for more even loading of passengers in the subway cars. This is because passengers will seek and line up at the loading zone where vacancy on the subway train is indicated to be available. If no vacancy is available in any loading zone then they will line up where the length of the que minus the vacancy displayed is the smallest. Since every effort is made to migrate passengers from the entrances to the sitting zones, and from the sitting zones to the exit zones, it is expected that the passenger density will be highest in the exit zones and lowest in the entrance zones when the subway train arrives at the next station. Speedy passenger loading is ensured simply because a predetermined number of passengers will already be well lined up and will be on-boarded to the free space provided in the entrance zones for each subway train compartment. Also, very speedy unloading of passengers is ensured simply because most of the deboarding passengers are already concentrated at the exit gate area of the subway train so that they can get off very quickly from the subway train to the platform. This speedy unloading process is further ensured simply because all boarding passengers are lined up in the loading areas which is typically sufficiently far away from the unloading area that no passenger counter flow will be encountered and thus the unloading area will be clear of passengers most of the time. After the unloading and the loading processes are simultaneously completed, all subway train gates will be closed and the subway train will be ready to move to the next station thus beginning the next passenger control cycle. It should be pointed out that all of the subway passenger loading control system objectives which have been previously stated will be accomplished through employment of this invention. Passenger loading/unloading time will be minimized through utilization of efficient concurrent loading and unloading through separate gates. Over crowding of subway passenger cars will be prevented by electronically controlling the number of passengers that are permitted to board each car of the subway train. The preprogrammed stop time at each station will be efficiently maintained by minimizing the passenger loading and unloading time. The invention described is also applicable for the currently existing two-gate train car design as a passenger control system although it may not be as efficient as the three-gate car design and this is presented in FIG. 6 through FIG. 10. Referring now to FIG. 6, a subway train 60 is shown to be stopped along side the passenger platform 61 and two gates 68 are shown to be open. Four PPS posts 62 are located at each loading gate. The passenger loading area 67 is surrounded by stationary fence 65, and fence gates 63, and passenger gate 66. Predetermined numbers of passengers will be permitted to enter the loading zone 67 through the gate 66 whose functionality is exactly the same as gate 51 shown in FIG. 5. A more detailed description of the gates 66 and their functions will be set forth hereinbelow. All passengers deboarding will pass between a pair of PPS posts 62 which are placed in the gate so that the number of passengers exiting from the subway train is electronically countable. Since the same gate will be used for boarding passengers there is a need to have the ability to distinguish the boarding and deboarding passengers. FIG. 7 shows a pair of PPS posts with two way sensors. Two infrared beam transmitters 72 and 74 are installed on the same post 76 but they are positioned apart by a selected distance, such as one inch, for example. Their respective receivers 73 and 75 are also installed on the same post 77, and are also positioned apart by a selected distance, such as one inch. If a passenger enters from the forward direction, the beginning of the beam block time for sensors 74 and 75 pair will be approximately 30 milliseconds sooner than that of sensors 72 and 75. This will be the opposite if the passenger enters the space between the sensor pairs in the rearward direction. By comparison of the timing blocks the computer can distinguish the difference between boarding and deboarding passengers and more accurately keep track of the number of passengers that are present in each car of the subway train at any given time. FIG. 8 is a perspective view of the loading area protection system of the loading platform which is quite similar to the system depicted in FIG. 5. The only difference is that the fence gate 63 is opened by motor 69 and rests at gate position 64, shown in broken lines, when most of the passengers have been off-loaded. This opening serves two purposes, first to open the passage to the subway train gates 68 for passengers in the loading area 67; secondly, to keep away passengers that are located outside of the loading zone for the subway train gates. The number of passengers that are present in the loading area is already counted. This number can be checked with the number counted by the sensors of PPS posts 62. The passenger control system set forth in FIG. 9 is similar to that shown in FIG. 6 except that PPS posts 82 are placed in the platform installation instead of within the subway train gates. The train car 80 will be of conventional nature and will not have passenger sensors of any kind. The platform passenger control station includes a central fence section having movable gates 87 and opposed extended fence sections 83. Movable fence or gate sections 85 are provided which cooperate with the central fence section to define a passenger loading or preboarding zone 89 for passengers who are counted by sensors as they enter through gates 87. During deboarding of passengers from the car 80 the movable fence or gate sections 85 are positioned as shown in full line to prevent entry of passengers from the preboarding zone 89 into the car. The deboarding passengers are counted as they pass through the sensor post arrays 82. After deboarding has been completed the gate or fence sections 85 are moved to the broken line positions 84 to thus permit movement of the passengers from the preboarding area 89 into the car 80. The passenger control system set forth in FIG. 10 is similar to that shown in FIG. 8 except that it has an extended fence 83 and sensor posts 82 located on the platform rather than on the subway cars. The passenger cars may therefore be of conventional nature as shown at 80 in FIG. 9. The platform passenger control installation is also similar to that shown in FIG. 9, the same reference numerals being used with reference to like passenger control components. The gates 85 may be positioned by the motor 88 which is of the same nature as gate motor 69 of FIG. 8. To control passenger loading most efficiently, it is most desirable to know how many passengers will be off-boarded from each car compartment at each station in advance. To accomplish this objective a push button destination station indicator 90 (detail is not shown) is attached to each passenger entry gate 87 which is also connected to the central computer system. To enter to the loading zone through gate 87, each passenger must push a button among an array of buttons which correspond to his destination station otherwise the gate 87 will not be opened. By knowing each passenger's destination when they are entering to the loading zone, the computer can identify the number of passengers to be off-boarded from each car compartment at each station well in advance and this information will be utilized for admitting the correct number of passengers to the loading area prior to the arrival of the train. As soon as the train car does open on train arrival at each station, the pre-admitted passengers will be able to board immediately simultaneously with deboarding of passengers that have reached their destination. The systems shown in FIGS. 9 and 10 are such that no modification is required on the subway train structure itself and all passenger control system components are installed on the platform and positioned for registry with the entrance gates and exit gates of the subway cars. If the system depicted in FIGS. 1 to 5 is implemented, all sensor systems are located inside of the subway train and the passenger loading platform area remains unaltered. The passenger loading and unloading control system of the present invention is intended to function as a solution for prevention of passenger overcrowding and it must function reliably under crowded conditions as typically occur during rush hours in large cities. If passengers are passing through the passenger system, whether located on a subway car, on the passenger platform, or on both and are passing the sensors one person at a time, then a simple sensor system such as those employed for elevator control systems might serve the purpose. However, if a group of passengers are jammed and pass through the sensor system, then reliable passenger counting with a simple sensor system becomes doubtful. Infrared beams, laser beams, ultrasonic waves, electromagnetic waves, thermal sensors, etc. are all potential candidates to serve as sensors for purposes of the present invention. Whatever type of signal (beam or waves) are employed for the sensor system, transmission and reflection methods are the most widely utilized methods and both methods are applicable for purposes of the present invention. The transmission method places transmitter and receiver pairs in face-to-face relation and thus permits a passenger to pass through the spaces between the sensor pairs to thus interrupt the beam projecting from the transmitters to the receivers. The number of passing passengers are known by counting the number of times the sensor beam is interrupted. The reflection method places the transmitter and receiver on the same side and the passing passengers reflect the signal from the transmitter and cause the reflected signal to be detected by the receiver. Thus the number of passengers passing the sensors become known by detecting the presence or absence of reflected signals by the sensor system as a function of time. Whether the transmission or reflect ion methods are employed, it is most desirable to utilize multiple sensor systems in order to improve the accuracy of passenger counting. As mentioned above, it is highly desirable that passenger counting be accomplished with some degree of accuracy. Although, 100% efficiency is not absolutely required. The term "multiple sensor system" implies either the utilization of many transmitter and receiver pairs or the use of an array of receivers per each transmitter or a combination of both. These multiple transmitter/receiver pairs can be arranged in three dimensions. There is an unlimited number of ways of designing the passenger counting sensor system and therefore, for purposes of the present invention, any passenger sensor and counting facility may be employed without departing from the spirit and scope of this invention. In order to demonstrate the feasibility of the system, one simple design example will be presented as follows: FIGS. 11 and 12 are respectively front and side views of a passenger gate that is provided with a multiple sensor system. In FIG. 11 passenger 111 passes through the space between a pair of sensor support posts 115. Elements 116 and 117 are multilevel beam transmitter and receiver pairs installed on the posts 115. A horizontal beam 118 is transmitted from the transmitter 116 to the receiver 117. Reference numeral 119 identifies the ceiling of the passenger compartment within the passenger car of a subway train. Slant beam transmitters 120 are positioned at the ceiling 19 of the passenger compartment and transmit the beams which are received by slant beam receivers which are located at the lower portion of the sensor support posts 115. Alternatively, the slant beam receiver 121 may be located at the floor of the subway car so as to establish vertical orientation for the beam, but it is not desirable to place the receiver on the floor for obvious reasons. The interval between a pair of vertical beam transmitters 120 is approximately one foot and their respective receivers 121 are approximately two feet. The reason for this spacing will be explained in detail hereinbelow. It should be pointed out that all horizontal beams 18 and slant beams 22 are co-planar. In other words, they are in the same vertical plane and conceptually forms a vertical beam curtain having minimal thickness. FIG. 12 is a side elevational view of the multiple sensor system of FIG. 11. Transmitters 120 and beams 122 are located in co-planar relation with the front vertical curtain and transmitters 130 and beams 132 are co-planar with the rear vertical beam curtain. The front and rear vertical beam curtains therefore define two parallel vertical planes and the gap or space between these two planes should not exceed a few inches since the gap or space between the front and rear sensor curtains is much smaller than the thickness of the body of a passenger, all beams on both curtains will be interrupted concurrently for some point of time during the period when a passenger 111 passes through the sensor system as shown in FIG. 12. With reference now to FIG. 13, there is illustrated an enlarged plan view of the sensor system with passengers 111, 112 and 113 shown in relation to the sensor system. As can be seen in FIG. 13, the back of the front passenger 111 and the front of the next passenger 112 are in contact as they pass through the gate defined by the sensors. In this situation, the horizontal beam 118 projecting from transmitter 116 to the receiver 117 will be continuously interrupted during the passage of both passengers through the gate and thus passengers 111 and 112 will be counted as a single passenger. On the other hand, the slanted beam 122 being projected from transmitter 120 to receiver 121 will be uninterrupted, thus the separation between passengers 111 and 112 can be recognized. In the event both passengers 111 and 112 should be bent forwardly with the upper body portions thereof in contact at the time they pass through the gate defined by the sensors, then the slant beam may fail to recognize the separation between the two passengers while the horizontal beam is very likely to be uninterrupted so that the separation of these two passengers can be electronically recognized. The passenger 113 is well separated from the passenger 112 so that all of the sensors will be uninterrupted after the passenger 112 has passed through the gate and before the passenger 113 has initiated entry through the gate. Accordingly, separation between passengers 112 and 113 would not present a problem from the standpoint of passenger counting. Although it is not shown in the drawings, the voltage detected by each receiver, which is an analog signal, will be digitized continuously with a predetermined sampling interval (perhaps 2 to 4 milliseconds). During the period when the beam is uninterrupted, the signal state will be defined as zero and when the beam is interrupted, the signal state will be defined as one (1) as shown in FIG. 14. In FIG. 14, it is assumed that there is a total of (k) numbers of sensors for each monitoring system and they are numbered sequentially. S 1 (t), S 2 (t), . . . , S k (t) represent a digitized time series monitored at receivers 1, 2, . . . k, respectively. Delta (t) is the sampling interval of the time series. If the passengers are well separated and thus pass in well separated relation through the sensor system, then these will be identified by a group of samples with a positive value of one (1) 140. The duration of the period 140 depends on the speed of passenger movement and the thickness of the body of the passenger. The periods of zero values shown at 141 must alternate with the positive values as shown in FIG. 14. A sequence of alternating positive and zero values 140 and 141 will represent the passing of one passenger through the sensor gate. The digitized sampled time series from each receiver will be transmitted to the central computer by means of a modem or any computer network for further processing. The time series representation of FIG. 15 is a simple sum of k number of time series when each passenger is well separated. When a passenger is positioned to completely interrupt all sensors at a given time, the summed value will be equal to k as shown at 150. During the time that no passenger is present in a position to interrupt any of the sensors, then the sum as shown in the graphical representation of FIG. 15 will be zero as identified by reference numeral 151. FIG. 15 is a graphical representation of the sum sensor time series signals which will very likely occur during rush hours when large numbers of passengers will be passing through the sensor gates in closely spaced, perhaps touching, perhaps overlapping relation. In this case, not all sensor will be uninterrupted completely between adjacent passengers. Consequently, the resulting summed sensor time series will depict a completely interrupted state 160 followed by a partially interrupted state 161 or a completely uninterrupted state 151 These sensor time series conditions will alternate as passengers pass through the gate as shown in the graphical representation of FIG. 16. A pair of completely interrupted time series 160 with either a partially interrupted time series 161 or completely uninterrupted time series 151 will represent movement of one passenger through the sensor gate. It should be pointed out that a central horizontal beam or slant beam sensor alone has potential to count two passengers as one, but the combined use of both horizontal and vertical beams for passenger detection reduces the probability of the occurrence of passenger miscount. By arranging transmitters and receivers in three dimensional relation, it is possible to design a system that will further reduce the probability of the occurrence of passenger miscount. Continuous digitization of an output voltage from a sensor is a well proven technology in the area of telecommunications, seismic survey, automatic system control, etc. Some existing systems can handle thousands of sensors simultaneously and the digitized time series can be transmitted to a computer and processed in real time on a routine basis. Since infrared and laser beam sensors, analog to digital converters, multi-channel multiplexers and personal computers are all commercially available, the passenger counting system of the present invention can readily benefit through use of existing technological components, thus promoting a wide range of design alternatives and alternative embodiments that are will within the scope of the present invention. It appears that the degree of sophistication of the passenger detection and control system will largely depend on the desired accuracy of the counting system. If the desired accuracy is 100%, then obviously, the counting system needs to be of fairly complex nature. On the other hand, if the passenger counting and control sensor system has a design accuracy of say 98% or so, then the simple design examples set forth in this specification will adequately function for the intended purposes of the present invention. In view of the foregoing, it is evident that the present invention is one well adapted to attain all of the objects and features hereinabove set forth, together with other objects and features which are inherent in the apparatus disclosed herein. As will be readily apparent to those skilled in the art, the present invention may be produced in other specific forms without departing from its spirit or essential characteristics. The present embodiment, is therefore, to be considered as illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of the equivalence of the claims are therefore intended to be embraced therein.
A passenger detection loading and unloading control system is provided for high volume passenger transporters such as subway trains and the like which electronically counts the passengers in each passenger compartment and prepositions passengers that intend to deboard at the next passenger loading and unloading platform and which electronically counts and prepositions a number of passengers at the next platform for boarding. The system further permits simultaneous loading and unloading of passengers without interference with passenger flow. Passengers on the transporter are numerically counted and those passengers intended to deboard the transporter at the next platform are also counted. Signals representing these counted passengers are continuously transmitted to a signal processing facility for processing. A predetermined time schedule for arrival and departure is established for the high volume passenger transporter in relation to each passenger loading and unloading platform. The processed passenger information from the transporter is communicated to the platform and utilized for controlling maximum loading of the transporter in compliance with the predetermined time schedule so that the transporter system functions in its most efficient passenger handling manner and keeps all transporters operating on the preestablished time schedule.
Concisely explain the essential features and purpose of the invention.
[ "FIELD OF THE INVENTION This invention relates generally to subway systems for mass transit of passengers in cities and more particularly concerns a subway passenger loading and unloading control system that minimizes subway overcrowding and renders the subway passenger handling system more efficient.", "BACKGROUND OF THE INVENTION This invention is described herein particularly as it relates to subway train systems and passenger control therefor.", "It is to be understood, however, that this invention has efficient application in any facility where passenger control is desired and therefore the example herein should not be limiting of the scope of this invention.", "It is well known that a subway is one of the most efficient passenger transportation systems in a large city.", "However, most of the subways in the world are confronted with a traffic congestion problem during rush hours.", "This congestion is mainly caused by over-loading of passengers into the subway which exceeds the limits of transportation capacity of the system.", "Train travel time delays and over crowding of subway train compartments during rush hours are a direct result of this over-loading.", "Two of the most important factors which govern the capacity of a subway transportation system are the subway train travel time from the station of origin to terminus and the maximum number of subway trains dispatchable during rush hours.", "The total travel time (TOT) of a subway train from the station of origin to terminus is generally composed of three time elements: 1) the sum of subway train interval travel time between two adjacent stations;", "2) the sum of passenger unloading and loading time at each station;", "and 3) the sum of extra waiting time in a station due to some uncontrollable circumstances.", "The maximum number of subway trains dispatchable (MTD) for a given time duration depends on TOT and the minimum distance on time interval allowed between two consecutive subway trains (MIT).", "It is obvious that the more subway trains that are dispatched, the more people can be transported but it is practically limited by the MTD.", "Since the MIT is more or less a fixed quantity for a given subway system for safety reasons and particularly it reaches to the limit during the rush hours, further reduction of the MIT is very unlikely.", "Thus it appears that the only viable option to increase a subway system's transportation capacity is to maximize the MTD by minimizing the TOT if we are constrained to utilize currently existing subway trains without any costly major remodifications to the subway system.", "In order to minimize the TOT of subway systems, all three time elements of the TOT should be minimized: 1) Interval Travel Time (ITT) Since the maximum speed of a subway train is limited, the minimum ITT exists for each station interval.", "The minimum subway train run time can be defined as the sum of minimum ITT and this quantity is a constant and can be attained in an ideal situation only.", "The real value of ITT during rush hours is very likely greater than the minimum ITT due to the slow down of a subway train caused by the loading and unloading delay of preceding subway trains.", "In order to minimize extra ITT delay, it is necessary to implement a method which will force each subway train to keep a preset or preprogrammed station stop time for each station without any exceptions.", "2) Passenger Loading and Unloading Time (PLT) This is the most critical time element within the TOT which increases the most during rush hours;", "and, effective reduction of PLT is the key for minimization of the TOT.", "Currently, a significant increase of PLT during rush hours is mostly caused by over-crowding of passengers and the lack of an efficient passenger loading control system in the existing subway train system.", "Most currently existing subway trains employ a two-door design.", "Each door is being utilized for both passenger loading and unloading so that the passenger flow through the door is bi-directional.", "It appears that the PLT for a bi-directional door system is almost twice that of the mono-directional door system which allows passengers to get in through an "Entrance Only"", "door and get out through an "Exit Only"", "door.", "(For example, a street car with three doors, two end doors assigned for "Entrance Only"", "and the middle for "Exit Only").", "This is because in the bi-directional door system passenger loading can only begin after the passenger unloading is completed, while for the mono-directional door system, the unloading and loading process can be done concurrently.", "The bi-directional door system has further problems under a crowded environment during rush hours.", "Usually, passengers inside of the subway train who stand near the exit door and passengers on the platform ready to get on the subway typically block the accessway for passengers who wish to get off and this further delays the passenger unloading process.", "On the other hand, for mono-directional door systems, the flow of passengers within a subway train compartment is mono-directional (entrance to exit) and no passenger on the platform will block the exit door thus, the unloading process will be more efficient than a bi-directional door system.", "3) Extra Waiting Time It appears that most of the subway train extra waiting time during rush hours is caused by the over crowding of passengers at several bottle neck subway stations.", "For example, at these bottleneck stations, some passengers try to get on already crowded subway trains and hang on near the door.", "This prevents the closing of subway train doors and causes further delay of departure of the subway train.", "Currently, subway operators of several large cities (Tokyo, Seoul, etc.), solve this problem by assigning passenger pushers to push passengers into the subway car compartment in order to close the door.", "In order to solve rush hour subway traffic congestion problems, it is most desirable to implement a subway passenger loading control system which will accomplish the following: 1) Minimize passenger loading and unloading time.", "2) Prevent over loading of passengers at each station for all subway trains at all times.", "3) Make all subway trains maintain a preprogrammed stop time at each station.", "This invention utilizes a computerized subway passenger loading and unloading monitoring system which is installed at each entrance and exit area as well as in the interior of subway train compartments.", "This enables us to keep track of the number of passengers entering and leaving the subway train as well as the flow of passengers inside of the subway train.", "By knowing this vital passenger flow information within the entire subway system, it is possible to accomplish the passenger control system objectives described above.", "BRIEF DESCRIPTION OF THE DRAWINGS So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be understood by reference to the embodiments thereof which are illustrated in the appended drawings.", "It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.", "IN THE DRAWINGS FIG. 1 is a front view of a subway train stopped at the subway station platform showing the gates opened and the process of passenger loading/unloading in progress.", "FIG. 2 is a detailed sketch of a subway train entrance gate where boarding passengers are entering the gate through pairs of passing passenger sensing posts.", "FIG. 3 is a top view of a subway train car compartment after removing the roof to show the partitioning of the interior area of the subway train compartment into three functional zones namely;", "entrance zone, seat zone, and exit zone.", "FIG. 4 is a detailed view of the boundary between the entrance zone and the seat zone.", "FIG. 5 is a perspective view of the passenger loading area fence system which might be used only for the congested subway station where very strict passenger loading control is needed.", "FIG. 6 is a top view of a two-gate subway train car compartment after removing the roof to show the arrangement of passing passenger sensor system and passenger loading system.", "FIG. 7 is a view of the two-way passing passenger sensing post.", "FIG. 8 is perspective view of the passenger loading area fence system for the two-gate subway train.", "FIG. 9 is a top view of a conventional two-gate subway train without any sensor posts.", "FIG. 10 is a perspective view of the passenger load area fence with the passing passenger sensing posts on the platform.", "FIG. 11 is a front elevational view of a passenger control gate constructed in accordance with the present invention and being provided with a multiple sensor system for passenger detection.", "FIG. 12 is a side elevational view of the multiple sensor passenger detection gate of FIG. 11.", "FIG. 13 is a plan view of the multiple sensor passenger detection gate of FIGS. 11 and 12, illustrating the presence of passengers in relation to the gate.", "FIG. 14 is a graphical representation of sequentially numbered sensors for a subway passenger control facility that functions according to the present invention.", "FIG. 15 is a graphical representation of a time series being the simple sum of a number of timed series relating to passenger separation in the passenger control system.", "FIG. 16 is a graphical representation of the summed sensor time series which is likely to occur during rush hours.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, two subway train cars 1 and 2 are connected by a subway train coupling 3.", "The subway train is stopped along the subway station platform 4 and an electrical passenger loading information display panel (or TV monitor) 6 is suspended from the station platform ceiling 5.", "Three passing passenger sensing (PPS) posts 9 are installed at the subway train entrance gate 7 and two boarding passengers are shown to be entering the subway train by passing between a pair of PPS posts 9 which will be used for counting the number of passengers entering into the subway train through this entrance.", "At the centrally located exit gate 8, five PPS posts 9 are installed and four deboarding passengers 10 are shown to be exiting the subway train parallel by passing between pairs of PPS posts 9 which serve for counting the number of passengers deboarding the subway train through this gate.", "Passenger loading traffic control signal 17 which is controlled by a computer installed in the subway train, has green and red lights;", "the green light signaling "Enter", and the red light signaling "Do Not Enter".", "The red light will be illuminated either when the number of passengers on board equals or exceeds the maximum capacity of the subway train compartment or a few seconds prior to the closing of the entrance gate in order to warn boarding passengers to stay on the platform so that the door can be closed without blocking.", "With reference to FIG. 2, the entrance gate 7 of the subway train is shown in detail.", "Infrared beam transmitters 11 and 13 and their respective beam receivers 12 and 14 are attached to the PPS posts 9 so that the entering passengers 15 will block the beam when they pass between the transmitter and receiver pairs.", "Each blocking will be counted as one passenger passing and thus count will be transmitted to the on-board computer to be described in detail hereinbelow.", "FIG. 3 is a plan view of the interior of a typical subway train compartment which shows a passenger movement monitoring sensor system to monitor the movement of passengers inside the subway train compartment.", "The subway train 1 is located on rails 21 which are supported in conventional manner by railroad ties 20.", "The subway car is shown to be stopped adjacent the passenger platform 4.", "All PPS posts installed on the platform side of the subway train gates are identified by reference numerals 9 and all PPS posts installed in the subway train gates in the opposite side of the passenger platform are depicted by reference numerals 16.", "The interior space of the subway train 1 is functionally divided into three zones by the sensor system.", "The front and rear entrance zones 41 and 42 are defined as an area combined by the PPS posts in the front and rear of the subway car 16, 25, 26, 27, 29, 30, 31 and 9.", "The passenger compartment includes front and rear passenger sitting zones 45 and 46 which are respectively defined by PPS posts 25, 26, 27, 29, 30, 31, 35, 37, and 33.", "The platform side and the opposite side of the platform exit zones 44 and 43 are respectively defined by PPS posts 9, 35, 37, 38, 37, and 34 and by PPS posts 16, 33, 37, 38, 37, and 34.", "Among the three zones, the entrance and exit zones are designated for standing passengers only, while there are seats in the passenger sitting zones 45 and 46.", "The sitting zone fence 34 is a barrier between the sitting and exit zones which has the purpose of causing passengers to move through the passenger sensors placed in between these two zones.", "The boundary between the entrance and the sitting zones is defined by an array of PPS posts 25, 26, 27, 29, 30 and 31.", "On the passenger platform, the passenger loading area located in front of the subway train entrance 7 is marked with a pair of solid lines 47 and a dotted line 48 for waiting passengers to line up.", "For some heavy traffic subway stations, the passenger loading area may need to be designated by a loading area fence 50 and gates 51.", "A prospective view of this fence diagram is depicted in FIG. 5 and will be described in detail hereinbelow.", "It should be pointed out that all sensors are connected with well shielded wires to the subway train compartment mini-computer 39.", "A computer 39 on each subway train car is linked to the subway train passenger monitoring computer 40 located in the subway train operators compartment (as shown in FIG. 6).", "While the subway train is traveling through the underground tunnel of the subway system, the subway train passenger monitoring computer 40 will continuously transfer information pertaining to the change of passenger distribution within each subway train compartment to a station computer 42 at the next passenger station or passenger loading and unloading platform wirelessly using cellular technology or other suitable means.", "All information received by the subway train station computer will be instantly relayed to a central passenger monitoring and control computer 47 by conventional means for further data processing.", "The elevational view of FIG. 4 shows the boundary between the entrance zone 41 and the sitting zone 45 in detail.", "The platform side PPS posts 31, 30, and 29 are blocked by a rotating cross bar 32 which has a hinge point 17 at one end thereof.", "The cross bar rests on top of the partitioning fence 28 with the hinge point being located in the middle of the fence 28.", "The opposite side platform PPS posts 25, 26, 27 are open to admit passengers moving into the exiting zone.", "These sensors will monitor the number of passengers moving from the entrance zone 41 to the sitting zone 45.", "Location of the entrance to sitting zone passage at the opposite side of this platform entrance is most important for the full utilization of spaces in the entrance zone.", "Further, the passenger entrance zone is in essence a passenger loading buffer for the sitting zone.", "If the passage between these two zones is placed in the middle, one half of the entrance zone which is the opposite side of the platform will become a dead space from the standpoint of passenger utilization and its space will therefore be wasted.", "A passenger dead space of this nature could be equivalent to reducing the length of loading area for the sitting zone by one half and thus should not be tolerated in passenger compartment design.", "FIG. 5 is a perspective view of a passenger loading area protection fence system which is located on the loading platform as shown in FIG. 3. If all passengers entering the entrance 7 of the subway train obey the rules of passenger courtesy and do not try to enter the subway car when the red light 17 is illuminated, this fence is not needed.", "A loading zone fence 50 and rotating gate 51 which are similar to the ones used in the subway station entrance, completely surrounds the loading zone.", "The gate 51 has an electronic passenger counting mechanism which is connected to the subway station computer and will physically limit the number of passenger entering to the loading zone at the passenger loading platform under the control of signals generated by the subway station computer.", "To prevent over-crowding of the subway train, it is necessary to control the number of passengers on board within the limit of the maximum passenger capacity for all subway train compartments.", "The total number of passengers on board a subway train compartment at any given time is simply the difference between the total number of passengers on-boarded through the entrance gates 7 and off-boarded through the exit gate 8.", "During rush hours, the subway train will be fully loaded beginning at some station away from the station of origin.", "Fully loaded implies that the number of passengers on board equals the designated capacity of the subway train compartment, but still there may be room available so that passengers can move around without too much difficulty.", "As soon as a fully loaded subway train closes all of its entry and exit gates and is ready for departure, an announcement will be made to request that passengers who will be deboarding at the next station move to the exit area (exit zone 44) which is most likely to be the least crowded at the time of departure due to unloading of passengers from this area at the current station.", "As passengers move from the sitting zones 45 and 46, to the exit zone 44, some vacant space (room) will occur in the sitting zone and this will allow passengers in the entrance zones 41 and 42 to move into the sitting zone 45 and 46 respectively.", "Since passengers go through the spaces between PPS posts 25, 26 and 27, the number of passengers moving from the entrance zones to the sitting zones is known.", "Thus the exact number of passengers remaining in the entrance zone is known as well.", "If some passengers remain in the entrance zones who should have moved to the sitting zones, the computer 39 will activate the speaker system in the entrance zones calling and requesting the passengers in the entrance areas move into the interior of the subway train to make room for passengers to be loaded in the next station.", "As passengers respond to this request, more passengers in the entrance zones will move into the sitting zone resulting in more passenger space availability in the entrance zones.", "The change of passenger distribution within the entrance zones 45 and 46, and in the exit zones 43 and 44 will be continuously transferred to the computer at the next station, while the subway train is traveling to the next station.", "Utilizing the detailed passenger distribution information which is transferred from the computer on the moving subway train to the computer in the next station together with the preprogrammed stop time at the station, the computer at the central control facility will determine the optimum number of passengers that will be permitted to load in each subway car entrance.", "It should be pointed out that the preprogrammed station stop time at each station should be strictly kept in order for all subway trains to operate on time as scheduled.", "Thus, the maximum number of passengers to be loaded will be limited to the number of passengers that can be loaded during the preprogrammed station stop time even if there are extra spaces available.", "Sometimes, it is possible that the central computer will command the unloading of passengers only and will not permit the loading of any passengers at less crowded stations, even if there is plenty of room available in the subway train compartment, in order to pick up more passengers (to ease an overcrowding problem) at a bottle neck station.", "In this way, overcrowding at a bottle neck station can be spread out to several less crowded stations.", "Once the optimum passenger loading decision is made, this information will be transmitted from the computer in the central passenger control facility to the computer in next station and this will be displayed on electronic passenger vacancy display 6 at the passenger platform prior to the arrival of the subway train.", "This feature will enable passengers to adjust their schedules or mode of travel in compliance with the condition of the subway system.", "Displaying passenger vacancy information at each passenger entrance at the station prior to the arrival of the subway train is very important for more even loading of passengers in the subway cars.", "This is because passengers will seek and line up at the loading zone where vacancy on the subway train is indicated to be available.", "If no vacancy is available in any loading zone then they will line up where the length of the que minus the vacancy displayed is the smallest.", "Since every effort is made to migrate passengers from the entrances to the sitting zones, and from the sitting zones to the exit zones, it is expected that the passenger density will be highest in the exit zones and lowest in the entrance zones when the subway train arrives at the next station.", "Speedy passenger loading is ensured simply because a predetermined number of passengers will already be well lined up and will be on-boarded to the free space provided in the entrance zones for each subway train compartment.", "Also, very speedy unloading of passengers is ensured simply because most of the deboarding passengers are already concentrated at the exit gate area of the subway train so that they can get off very quickly from the subway train to the platform.", "This speedy unloading process is further ensured simply because all boarding passengers are lined up in the loading areas which is typically sufficiently far away from the unloading area that no passenger counter flow will be encountered and thus the unloading area will be clear of passengers most of the time.", "After the unloading and the loading processes are simultaneously completed, all subway train gates will be closed and the subway train will be ready to move to the next station thus beginning the next passenger control cycle.", "It should be pointed out that all of the subway passenger loading control system objectives which have been previously stated will be accomplished through employment of this invention.", "Passenger loading/unloading time will be minimized through utilization of efficient concurrent loading and unloading through separate gates.", "Over crowding of subway passenger cars will be prevented by electronically controlling the number of passengers that are permitted to board each car of the subway train.", "The preprogrammed stop time at each station will be efficiently maintained by minimizing the passenger loading and unloading time.", "The invention described is also applicable for the currently existing two-gate train car design as a passenger control system although it may not be as efficient as the three-gate car design and this is presented in FIG. 6 through FIG. 10.", "Referring now to FIG. 6, a subway train 60 is shown to be stopped along side the passenger platform 61 and two gates 68 are shown to be open.", "Four PPS posts 62 are located at each loading gate.", "The passenger loading area 67 is surrounded by stationary fence 65, and fence gates 63, and passenger gate 66.", "Predetermined numbers of passengers will be permitted to enter the loading zone 67 through the gate 66 whose functionality is exactly the same as gate 51 shown in FIG. 5. A more detailed description of the gates 66 and their functions will be set forth hereinbelow.", "All passengers deboarding will pass between a pair of PPS posts 62 which are placed in the gate so that the number of passengers exiting from the subway train is electronically countable.", "Since the same gate will be used for boarding passengers there is a need to have the ability to distinguish the boarding and deboarding passengers.", "FIG. 7 shows a pair of PPS posts with two way sensors.", "Two infrared beam transmitters 72 and 74 are installed on the same post 76 but they are positioned apart by a selected distance, such as one inch, for example.", "Their respective receivers 73 and 75 are also installed on the same post 77, and are also positioned apart by a selected distance, such as one inch.", "If a passenger enters from the forward direction, the beginning of the beam block time for sensors 74 and 75 pair will be approximately 30 milliseconds sooner than that of sensors 72 and 75.", "This will be the opposite if the passenger enters the space between the sensor pairs in the rearward direction.", "By comparison of the timing blocks the computer can distinguish the difference between boarding and deboarding passengers and more accurately keep track of the number of passengers that are present in each car of the subway train at any given time.", "FIG. 8 is a perspective view of the loading area protection system of the loading platform which is quite similar to the system depicted in FIG. 5. The only difference is that the fence gate 63 is opened by motor 69 and rests at gate position 64, shown in broken lines, when most of the passengers have been off-loaded.", "This opening serves two purposes, first to open the passage to the subway train gates 68 for passengers in the loading area 67;", "secondly, to keep away passengers that are located outside of the loading zone for the subway train gates.", "The number of passengers that are present in the loading area is already counted.", "This number can be checked with the number counted by the sensors of PPS posts 62.", "The passenger control system set forth in FIG. 9 is similar to that shown in FIG. 6 except that PPS posts 82 are placed in the platform installation instead of within the subway train gates.", "The train car 80 will be of conventional nature and will not have passenger sensors of any kind.", "The platform passenger control station includes a central fence section having movable gates 87 and opposed extended fence sections 83.", "Movable fence or gate sections 85 are provided which cooperate with the central fence section to define a passenger loading or preboarding zone 89 for passengers who are counted by sensors as they enter through gates 87.", "During deboarding of passengers from the car 80 the movable fence or gate sections 85 are positioned as shown in full line to prevent entry of passengers from the preboarding zone 89 into the car.", "The deboarding passengers are counted as they pass through the sensor post arrays 82.", "After deboarding has been completed the gate or fence sections 85 are moved to the broken line positions 84 to thus permit movement of the passengers from the preboarding area 89 into the car 80.", "The passenger control system set forth in FIG. 10 is similar to that shown in FIG. 8 except that it has an extended fence 83 and sensor posts 82 located on the platform rather than on the subway cars.", "The passenger cars may therefore be of conventional nature as shown at 80 in FIG. 9. The platform passenger control installation is also similar to that shown in FIG. 9, the same reference numerals being used with reference to like passenger control components.", "The gates 85 may be positioned by the motor 88 which is of the same nature as gate motor 69 of FIG. 8. To control passenger loading most efficiently, it is most desirable to know how many passengers will be off-boarded from each car compartment at each station in advance.", "To accomplish this objective a push button destination station indicator 90 (detail is not shown) is attached to each passenger entry gate 87 which is also connected to the central computer system.", "To enter to the loading zone through gate 87, each passenger must push a button among an array of buttons which correspond to his destination station otherwise the gate 87 will not be opened.", "By knowing each passenger's destination when they are entering to the loading zone, the computer can identify the number of passengers to be off-boarded from each car compartment at each station well in advance and this information will be utilized for admitting the correct number of passengers to the loading area prior to the arrival of the train.", "As soon as the train car does open on train arrival at each station, the pre-admitted passengers will be able to board immediately simultaneously with deboarding of passengers that have reached their destination.", "The systems shown in FIGS. 9 and 10 are such that no modification is required on the subway train structure itself and all passenger control system components are installed on the platform and positioned for registry with the entrance gates and exit gates of the subway cars.", "If the system depicted in FIGS. 1 to 5 is implemented, all sensor systems are located inside of the subway train and the passenger loading platform area remains unaltered.", "The passenger loading and unloading control system of the present invention is intended to function as a solution for prevention of passenger overcrowding and it must function reliably under crowded conditions as typically occur during rush hours in large cities.", "If passengers are passing through the passenger system, whether located on a subway car, on the passenger platform, or on both and are passing the sensors one person at a time, then a simple sensor system such as those employed for elevator control systems might serve the purpose.", "However, if a group of passengers are jammed and pass through the sensor system, then reliable passenger counting with a simple sensor system becomes doubtful.", "Infrared beams, laser beams, ultrasonic waves, electromagnetic waves, thermal sensors, etc.", "are all potential candidates to serve as sensors for purposes of the present invention.", "Whatever type of signal (beam or waves) are employed for the sensor system, transmission and reflection methods are the most widely utilized methods and both methods are applicable for purposes of the present invention.", "The transmission method places transmitter and receiver pairs in face-to-face relation and thus permits a passenger to pass through the spaces between the sensor pairs to thus interrupt the beam projecting from the transmitters to the receivers.", "The number of passing passengers are known by counting the number of times the sensor beam is interrupted.", "The reflection method places the transmitter and receiver on the same side and the passing passengers reflect the signal from the transmitter and cause the reflected signal to be detected by the receiver.", "Thus the number of passengers passing the sensors become known by detecting the presence or absence of reflected signals by the sensor system as a function of time.", "Whether the transmission or reflect ion methods are employed, it is most desirable to utilize multiple sensor systems in order to improve the accuracy of passenger counting.", "As mentioned above, it is highly desirable that passenger counting be accomplished with some degree of accuracy.", "Although, 100% efficiency is not absolutely required.", "The term "multiple sensor system"", "implies either the utilization of many transmitter and receiver pairs or the use of an array of receivers per each transmitter or a combination of both.", "These multiple transmitter/receiver pairs can be arranged in three dimensions.", "There is an unlimited number of ways of designing the passenger counting sensor system and therefore, for purposes of the present invention, any passenger sensor and counting facility may be employed without departing from the spirit and scope of this invention.", "In order to demonstrate the feasibility of the system, one simple design example will be presented as follows: FIGS. 11 and 12 are respectively front and side views of a passenger gate that is provided with a multiple sensor system.", "In FIG. 11 passenger 111 passes through the space between a pair of sensor support posts 115.", "Elements 116 and 117 are multilevel beam transmitter and receiver pairs installed on the posts 115.", "A horizontal beam 118 is transmitted from the transmitter 116 to the receiver 117.", "Reference numeral 119 identifies the ceiling of the passenger compartment within the passenger car of a subway train.", "Slant beam transmitters 120 are positioned at the ceiling 19 of the passenger compartment and transmit the beams which are received by slant beam receivers which are located at the lower portion of the sensor support posts 115.", "Alternatively, the slant beam receiver 121 may be located at the floor of the subway car so as to establish vertical orientation for the beam, but it is not desirable to place the receiver on the floor for obvious reasons.", "The interval between a pair of vertical beam transmitters 120 is approximately one foot and their respective receivers 121 are approximately two feet.", "The reason for this spacing will be explained in detail hereinbelow.", "It should be pointed out that all horizontal beams 18 and slant beams 22 are co-planar.", "In other words, they are in the same vertical plane and conceptually forms a vertical beam curtain having minimal thickness.", "FIG. 12 is a side elevational view of the multiple sensor system of FIG. 11.", "Transmitters 120 and beams 122 are located in co-planar relation with the front vertical curtain and transmitters 130 and beams 132 are co-planar with the rear vertical beam curtain.", "The front and rear vertical beam curtains therefore define two parallel vertical planes and the gap or space between these two planes should not exceed a few inches since the gap or space between the front and rear sensor curtains is much smaller than the thickness of the body of a passenger, all beams on both curtains will be interrupted concurrently for some point of time during the period when a passenger 111 passes through the sensor system as shown in FIG. 12.", "With reference now to FIG. 13, there is illustrated an enlarged plan view of the sensor system with passengers 111, 112 and 113 shown in relation to the sensor system.", "As can be seen in FIG. 13, the back of the front passenger 111 and the front of the next passenger 112 are in contact as they pass through the gate defined by the sensors.", "In this situation, the horizontal beam 118 projecting from transmitter 116 to the receiver 117 will be continuously interrupted during the passage of both passengers through the gate and thus passengers 111 and 112 will be counted as a single passenger.", "On the other hand, the slanted beam 122 being projected from transmitter 120 to receiver 121 will be uninterrupted, thus the separation between passengers 111 and 112 can be recognized.", "In the event both passengers 111 and 112 should be bent forwardly with the upper body portions thereof in contact at the time they pass through the gate defined by the sensors, then the slant beam may fail to recognize the separation between the two passengers while the horizontal beam is very likely to be uninterrupted so that the separation of these two passengers can be electronically recognized.", "The passenger 113 is well separated from the passenger 112 so that all of the sensors will be uninterrupted after the passenger 112 has passed through the gate and before the passenger 113 has initiated entry through the gate.", "Accordingly, separation between passengers 112 and 113 would not present a problem from the standpoint of passenger counting.", "Although it is not shown in the drawings, the voltage detected by each receiver, which is an analog signal, will be digitized continuously with a predetermined sampling interval (perhaps 2 to 4 milliseconds).", "During the period when the beam is uninterrupted, the signal state will be defined as zero and when the beam is interrupted, the signal state will be defined as one (1) as shown in FIG. 14.", "In FIG. 14, it is assumed that there is a total of (k) numbers of sensors for each monitoring system and they are numbered sequentially.", "S 1 (t), S 2 (t), .", ", S k (t) represent a digitized time series monitored at receivers 1, 2, .", "k, respectively.", "Delta (t) is the sampling interval of the time series.", "If the passengers are well separated and thus pass in well separated relation through the sensor system, then these will be identified by a group of samples with a positive value of one (1) 140.", "The duration of the period 140 depends on the speed of passenger movement and the thickness of the body of the passenger.", "The periods of zero values shown at 141 must alternate with the positive values as shown in FIG. 14.", "A sequence of alternating positive and zero values 140 and 141 will represent the passing of one passenger through the sensor gate.", "The digitized sampled time series from each receiver will be transmitted to the central computer by means of a modem or any computer network for further processing.", "The time series representation of FIG. 15 is a simple sum of k number of time series when each passenger is well separated.", "When a passenger is positioned to completely interrupt all sensors at a given time, the summed value will be equal to k as shown at 150.", "During the time that no passenger is present in a position to interrupt any of the sensors, then the sum as shown in the graphical representation of FIG. 15 will be zero as identified by reference numeral 151.", "FIG. 15 is a graphical representation of the sum sensor time series signals which will very likely occur during rush hours when large numbers of passengers will be passing through the sensor gates in closely spaced, perhaps touching, perhaps overlapping relation.", "In this case, not all sensor will be uninterrupted completely between adjacent passengers.", "Consequently, the resulting summed sensor time series will depict a completely interrupted state 160 followed by a partially interrupted state 161 or a completely uninterrupted state 151 These sensor time series conditions will alternate as passengers pass through the gate as shown in the graphical representation of FIG. 16.", "A pair of completely interrupted time series 160 with either a partially interrupted time series 161 or completely uninterrupted time series 151 will represent movement of one passenger through the sensor gate.", "It should be pointed out that a central horizontal beam or slant beam sensor alone has potential to count two passengers as one, but the combined use of both horizontal and vertical beams for passenger detection reduces the probability of the occurrence of passenger miscount.", "By arranging transmitters and receivers in three dimensional relation, it is possible to design a system that will further reduce the probability of the occurrence of passenger miscount.", "Continuous digitization of an output voltage from a sensor is a well proven technology in the area of telecommunications, seismic survey, automatic system control, etc.", "Some existing systems can handle thousands of sensors simultaneously and the digitized time series can be transmitted to a computer and processed in real time on a routine basis.", "Since infrared and laser beam sensors, analog to digital converters, multi-channel multiplexers and personal computers are all commercially available, the passenger counting system of the present invention can readily benefit through use of existing technological components, thus promoting a wide range of design alternatives and alternative embodiments that are will within the scope of the present invention.", "It appears that the degree of sophistication of the passenger detection and control system will largely depend on the desired accuracy of the counting system.", "If the desired accuracy is 100%, then obviously, the counting system needs to be of fairly complex nature.", "On the other hand, if the passenger counting and control sensor system has a design accuracy of say 98% or so, then the simple design examples set forth in this specification will adequately function for the intended purposes of the present invention.", "In view of the foregoing, it is evident that the present invention is one well adapted to attain all of the objects and features hereinabove set forth, together with other objects and features which are inherent in the apparatus disclosed herein.", "As will be readily apparent to those skilled in the art, the present invention may be produced in other specific forms without departing from its spirit or essential characteristics.", "The present embodiment, is therefore, to be considered as illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of the equivalence of the claims are therefore intended to be embraced therein." ]
FIELD OF THE INVENTION The present invention is directed toward a device for and method of injecting a fluid into a bale of forage materials. BACKGROUND OF THE INVENTION Animals are fed grains, forage feed stuffs for roughage, such as hay and/or straw, and liquid nutrient supplements. A convenient means of administering the liquid nutrient supplements has been to spray or pour the liquid onto the forage feed stuffs before distributing it to the animal feeding areas. This process of spraying or pouring, however, is inconvenient, labour intensive and imprecise. Often nutrients are wasted and more than the required amount is added to compensate for the amounts which are wasted. A method is required for applying liquid nutrients to a feed bale which prevents waste and can be carried out at a convenient time, such as during the bale handling at harvest or just prior to distribution to animals. Devices for injecting fluid into feed bales are known as described by U.S. Pat. No. 4,606,172 issued August 1986 to Miller. The prior device has a plurality of spikes for driving into the bale to deliver ammonia therethrough into the bale. An injection device is required which is able to accommodate the forces imparted to the injection spikes during insertion into the bale. An injection device is also required which can be used to control precisely the amount of fluid inserted into the bale. SUMMARY OF THE INVENTION A device for injecting a bale with a fluid through a hollow spike or spikes is disclosed which is able to accommodate the forces imparted on the spikes during driving into the bale. A device is also taught which can be adjusted to inject a selected amount of fluid into the bale without continuous monitoring of the volume being injected. In accordance with a broad aspect of the present invention, there is provided a device for injecting a fluid into a bale comprising: at least one injection spike having passage therethrough; a frame for supporting the spike; a resilient member attached between the spike and the frame and securing the spike to the frame; and a fluid feed system for injecting a fluid from a fluid source through the passage. In accordance with another aspect of the present invention, there is provided a device for injecting a fluid into a bale comprising: at least one injection spike having a passage therethrough; a frame for supporting the spike; and a fluid feed system for injecting a fluid from a fluid source through the passage including a fluid displacement chamber and means to displace a selected amount of fluid from the system through the passage. A method for injecting a fluid into a bale is also disclosed. In accordance with a broad aspect of the present invention there is provided a method for injecting a fluid into a bale comprising: providing a device including at least one injection spike having a passage therethrough, a frame for supporting the spike, and a fluid feed system for injecting a fluid from a fluid source through the passage including a fluid displacement chamber and means to displace a selected amount of fluid from the system through the passage. In a preferred embodiment, the fluid feed system for displacing a selected amount of the fluid from the system includes a fluid displacement means having a housing defining an internal chamber, a one way inlet to the chamber and a one way outlet from the chamber, the chamber containing a piston driven to sweep a selected volume of the chamber to displace a selected volume of fluid from the chamber; selecting the internal volume which is to be swept by the piston; inserting the spike into the bale; and actuating the fluid displacement chamber to displace the selected volume of fluid into the bale. Thus, in accordance with a further broad aspect of the present invention, there is provided a method for injecting liquid nutrient supplements to a bale comprising: providing a bale; piercing the bale with a hollow spike; and inserting liquid nutrient into the interior of the bale through the hollow spike. In one embodiment this is accomplished using a device including at least one injection spike having an internal passage therethrough, a frame for supporting the spike and means for injecting liquid nutrients from a liquid source through the internal passage of the spike. BRIEF DESCRIPTION OF THE INVENTION The device of the present invention is useful for all types of bales which are prepared in a way that permits insertion of a spike therein. The device includes at least one injection spike having a passage therethrough, a frame for supporting the spike and a fluid feed system for injecting a fluid from a fluid source through the passage of the spike. In one embodiment of the invention, the spike of the device is sized to be easily inserted into a bale and is preferably slender and elongate having a tapered tip at its outer end. The spike preferably is sized to extend generally to the centre of the bale and has a diameter such that a hole does not remain in the bale after removal of the spike from the bale. This prevents the formation after removal of the spike of an opening in the bale through which the injected fluid can leak from the bale. The spike is formed of a durable material such as, for example, stainless steel. The spike is supported by a frame. The frame can take any suitable form. In one embodiment it is a plate member. In another embodiment, the frame is formed as a pair of facing arms which are moveable to approach the bale on opposite sides. The frame can be modified in any desired way to facilitate insertion of the spike into a bale and to support the spike against the forces inherent in such insertion. The frame can also be modified to permit it to be mounted on a farm machine for transport. In one embodiment of the invention, a device is provided wherein a resilient member is disposed between the spike and the frame. The resilient member acts to secure the spike to extend out from the frame in a selected orientation, but permits the spike to be moved out of that selected orientation by application of a selected minimum force to the spike. By action of the resilient member, the spike will return to substantially its selected orientation when selected minimum the force is removed. The resilient member reduces deformation and shearing of the spike and, therefore, extends the useable life of the spike and the device. The resilient member can be any suitable member such as a spring or an elastomeric material. The device further includes a fluid feed system for injecting a fluid from a fluid source through the passage of the spike. The system can be any suitable system for injection of fluids and can include for, example pumps, valves, fluid conduit and seals. In one embodiment, the fluid feed system includes a fluid displacement means. The fluid displacement means includes a chamber having an internal piston driven by a ram. A stop on the ram determines the internal chamber volume which is swept by the piston and therefore, the amount of fluid which is displaced from the chamber by the piston during the stroke of the piston. Preferably, the stop can be adjustable along the ram to select the chamber volume which is swept by the piston. The device of the present invention can be used to inject a fluid into a bale. In a preferred method, liquid nutrient supplements are injected into a feed bale. Liquid nutrient supplements are known and contain various formulations of proteins, vitamins, minerals and carbohydrates. Preferably, the liquid nutrients are injected into straw bales according to the method of the present invention. This causes the straw, which is normally not readily consumed by cattle, to be more palatable to the cattle and to have greater nutritional content. In one embodiment, the method provides that a selected volume of nutrients is injected to the bale and fed to the animals with the bale. This can be done after formation of the bale before storing the bale or, preferably, just prior to feeding the bale to the animals. Injection of the nutrient just prior to feeding avoids breakdown of the nutrients and permits adjustment of the amount injected depending on feed requirements at the time. BRIEF DESCRIPTION OF THE DRAWINGS A further, detailed, description of the invention, briefly described above, will follow by reference to the following drawings of specific embodiments of the invention, which depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. In the drawings: FIG. 1 is a perspective view of an injection device according to the present invention with the frame partially cut away; FIG. 2 is a sectional view of an injection spike useful in the present invention; FIG. 3A is a front elevation view of another embodiment of an injection device according to the present invention; FIG. 3B is a perspective view of a bale stabilizer attachment useful in the embodiment of FIG. 3A shown attached to a frame bar; FIG. 4A is a schematic view of a fluid flow system useful in the present invention; FIG. 4B is a front elevational view of a fluid displacement chamber useful in the present invention with the housing shown cut away; and FIG. 4C is a sectional view through line 4C--4C of FIG. 4B. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, a device according to the present invention is shown having a plurality of spikes 10 supported by a frame formed as a plate 12. The device shown in FIG. 1 is intended for use to inject fluids into a circular bale, thus the spikes 10 are spaced on plate 12 so as to penetrate the central area of such a bale. In particular, a circular bale generally has a diameter of between about 4 to 6 feet. Thus, spikes 10 are spaced about an area having a diameter of about 47 inches. Preferably, the plate is circular in plan view having a diameter of 48 inches. The plate is preferably formed of steel. Each spike is preferably slender and elongate to facilitate insertion into a bale. Preferably also, the spikes are tapered at their outer ends 10". The spikes are selected such that their ends 10" extend a suitable distance into the bale. For example, in a preferred embodiment for use with a circular bale having a length of about 4 to 5 feet, the probes are selected to be about 22 inches in length. Preferably, the spikes are selected such that when they are removed from a bale, a wound will not be left in the bale. For example, in a preferred embodiment the spike has a diameter of less than about 1 inch and preferably has a 1/2 inch outer diameter. Preferably, the spikes are formed of a strong durable material, such as for example stainless steel tubing. Each spike 10 is threaded at its inner end 10' and is engaged in a threaded bore 14 of a coupler 15. Coupler 15 is retained, such as by welding, in a coil spring 16 which is secured to plate 12, such as by welding. Spring 16 normally maintains spike 10 in a position substantially perpendicular to plate 12. Application of a force which is sufficient to overcome the tension in spring 16 will move spike 10 out of the perpendicular position and also provides that the spike will return to the substantially perpendicular position, when the force is removed. The spring can be replaced by any resilient member which provides for such movement. Preferably, the spring is selected to permit the spike to be moved out of its substantially perpendicular position by application of a force of between 20 and 80 pounds of pressure (psig) perpendicular to the long axis of the spike at its tip and preferably 50 pounds of pressure. Preferably, the spring is a heavy gauge coil spring welded to a washer 18 which is in turn welded to plate 12. When the plate 12 and spike 10 are of the dimensions stated above as being preferred, the coil spring is preferably a 2 inch OD, 1 3/4 inch ID and 2 1/2-3 inch long steel coil spring having a tensile strength of 200,000 psi. Each spike 10 has a passage 10a therethrough. Passage 10a extends axially through spike 10 and is in communication at its inlet end with bore 14 of threaded coupler 15. The outlet end of each passage 10a communicates with at least one exit port 30 in the spike adjacent its outer end. A fluid-tight seal is provided at each point of connection such as for example by hydraulic line coupling means or o-rings (not shown). Plate 12 has apertures 20 formed therethrough for passage of fluid lines 22 which extend between bore 14 of coupler 15 and a fluid distribution chamber 24 (FIG. 4a), mounted on the rear side of plate 12. Fluid lines 22 provide a fluid-tight conduit from chamber 24 to coupler 15. Connections are sealed by any suitable means against passage of fluids. A fluid feed circuit is set up whereby a fluid source such as a supply tank (80 in FIG. 4A) is in fluid communication with exit ports 30 of the spikes 10 by conduit means including distribution chamber 24, feed lines 22, bore 14 and spike passage 10a. A suitable regulator is provided for regulating the flow of fluid from the fluid source through the conduits and passaging for injection into a bale impaled on spikes 10. In a preferred embodiment as shown in FIG. 2, a ball valve 31 is mounted at the outer end of each spike between passage 10a and exit port 30 to regulate the flow of fluid from the spikes. Valve 31 comprises a housing 32 having an inner chamber 34, with at least one exit port 30 extending through the housing in communication with the inner chamber. Preferably, housing 32 has a tapered tip 35 to facilitate insertion into a bale. Preferably, tip 35 is threadably engaged to housing 32 so that tip 35 can be replaced without replacing the entire housing. Valve 31 is preferably secured to spike 10 by threading at 36 which facilitates repair or replacement. A ball 40 is seated against the outlet opening 42 of passage 10a and is maintained in position by a spring 44 acting between an end wall 46 of inner chamber 34 and ball 40. Ball 40 will normally provide a fluid-tight seal against opening 42 unless fluid flows at a pressure sufficient to overcome the tension in spring 44 to move ball 40 away from opening 42. The tension in spring 44 can be adjusted by tightening tip 35 onto housing 32. Preferably, the valve is selected to be opened by fluid at 30 pounds pressure. Another embodiment of the device is shown in FIGS. 3A and 3B. The device has a frame 50 having mounted thereon a mounting attachment 52 for connection to a cherry picker implement arm 53. Mounting attachments for cherry pickers are known and will not be described herein. Any other mounting attachment can be used for transport of the device by another farm implement. In the preferred embodiment, however, the frame is attached to an implement which provides for vertical movement of the device. Frame 50 includes a top bar 56 carrying a pair of spaced, downwardly extending arms 58, 59 at the outer ends of which spiked plates 60 are mounted. FIG. 3A shows the arms in open position aligned for movement towards each other and insertion into bale 62 positioned on a ground surface 63. Spiked plates 60 each include plate 12 and spikes 10 and are preferably as described in relation to plate 12 of FIG. 1 and having spikes and spike mounting arrangements as described in relation to FIG. 2. Top bar 56 has formed thereon or attached thereto roller tracks 64 to accept and retain roller wheels 65 (shown in phantom) secured onto arms 58, 59 by brackets 66 and pins 67. Roller wheels 65 are free to ride along tracks 64 and thereby move arms 58, 59 along bar 56. To drive the movement of the arms along the bar, hydraulic cylinders 68, 69 extend between arms 58, 59, respectively and a central mounting flange 70 on bar 56. Preferably, cylinders 68, 69 are calibrated, as is known, to drive arms 58, 59 at the same rate and cylinders 68, 69 are connected by a line 71 extending between them. Cylinders 68, 69 are further connected by lines 72 to a hydraulic fluid source and a standard control mechanism. The action of the cylinders is controlled by an operator through the control mechanism. Instead of the roller track and hydraulics arrangement as shown, the movement of the arms relative to each other can be driven by any other suitable drive means. Fluid feed lines 74 lead from a fluid source (not shown) to spiked plates 60. Lines are formed preferably of hydraulic hose, rubber hose and/or tubing. A bale stabilizing means depends downwardly from bar 56 intermediate arms 58, 59. The means includes a pair of arms 76 each having positioned at its lower end a stop plate 77 for abutting against a bale to be injected. Bale stabilizing spikes 78 (FIG. 3B) extend from stop plates 77. A bar 79 extends between the stop plates to strengthen the arrangement. It is to be understood that any number of arms will work. For example, the pair of arms shown can be replaced by one which is located substantially centrally. The length of arm 76 is preferably selected relative to the distance of the spiked plate 60 from bar 56 such that when stop plate 78 rests on the bale, the spikes are positioned for entry into the bale. Preferably, the length of the arm 76 is selected such that spikes 10 are positioned centrally relative to the bale, in preparation for insertion into the bale. Referring to FIGS. 4A, 4B and 4C, a fluid feed system useful in the present invention comprises a fluid source 80, a line 82 leading from source 80 to a fluid displacement means 84, line 74 leading from means 84 to fluid distribution chamber 24 and lines 22 leading to the passages of spikes 10. The fluid feed system is formed to be substantially fluid-tight preferably to contain internal fluid pressures of between about 25 to 80 pounds pressure. The fluid source can be, for example, a tank carried on a farm implement. Lines 82, 74, 22 can be formed from any suitable fluid-tight materials such as hydraulic lines or tubing. All connections are fluid-tight. Fluid distribution chamber 24 can be formed in any suitable way for distribution of fluids under pressure to lines 22. Preferably, chamber 24 is mounted on plate 12 and is formed by four 4"×4" tubes 86 extending from a central hub 88. Fluid displacement means 84 includes a housing 89 which defines a cylindrical chamber 89a. Preferably, housing 89 is formed from hydraulic cylinder tubing having a polished inner surface. The cylindrical chamber 89a is selected to have a volume corresponding to the range of volumes which is desired to be injected using the device. Leading into the chamber, according to the direction of fluid flow, is an inlet line 90 with a one-way check valve 91. Valve 91 is selected to permit fluid flow in a direction, indicated by arrow A, into chamber 89a and to block flow in an opposite direction. Leading away from the chamber is outlet line 92 with a second one-way check valve 93. The second valve 93 is selected to permit fluid flow in a direction, indicated by arrow B, out of chamber 89a and to block flow in an opposite direction. A piston 94 is contained in chamber 89a and is connected to a ram 95. Ram 95 is driven by a hydraulic cylinder 96. When ram 95 is driven by cylinder 96, piston 94 is moved within chamber 89a. Piston 94 is selected to form a fluid tight seal against the inner cylindrical surface of the housing. In one embodiment in which liquid is injected, the piston has a first plate 105, a second plate 107 and sandwiched therebetween a rubber sheet 109. Plates 105 and 107 have a slightly smaller diameter than the chamber diameter. Rubber sheet 109 has slightly larger diameter than the diameter of the chamber and a thickness of about 1/2 inch. Ram 95 is attached to plate 107. Bolts 111 are welded onto plate 105 and extend through apertures in rubber sheet 109 and plate 107 where nuts 113 are threadably engaged onto bolts 111. To adjust the seal of the piston against the inner surface of the chamber, nuts 113 can be tightened on bolts 111 to force plates 105 and 107 closer together and to urge rubber sheet 109 to be expanded outwardly. When the system, and thereby the displacement means, is fully charged with fluid, any movement of piston 94 within chamber 89a, will cause a flow of fluid through the system. In particular, when the ram and, thereby, the piston are driven by cylinder 96 in the direction indicated by arrow c, fluid will be drawn from fluid source 80 through check valve 91 into chamber 89a and when the ram and the piston are driven by the cylinder in the direction indicated by arrow d, fluid will be forced from the chamber through valve 93 out through the exit ports 30 in spikes 10. The volume of chamber 89a which is swept by piston 94 is selected to correspond with the volume of fluid which is to be injected into the bale. To select the volume of the chamber which is swept by the piston from the position in which the ram is most withdrawn from the chamber, preferably, a stop 98 is securely positioned by a lock pin 98a on ram 95 to limit the extent to which the ram can be driven along chamber 89a. The stop can abut against housing 89 or, alternately, as shown, the stop can abut against a collar 99 secured about the ram by screws 100 between the stop and the housing. The collar is selected to have a shape or minimum internal diameter to prevent the stop from passing beneath it. To select the volume which is swept by the piston, the collar can be replaced with a collar having a different length. Preferably, a set of collars are provided having different lengths and are marked to indicated which volume of fluid will be displaced using any selected collar. Alternately or in addition, to select the volume which is swept by a piston stroke, the stop can be locked using pin 98a into a selected position along the ram. Preferably, the ram is marked with calibrations 101 to indicate the volume at any stop location along the ram. In use, the device is positioned relative to a bale such that the spikes are aligned for insertion into the bale. The spikes are then driven into the bale and fluid is injected therethrough. Using the device of FIG. 3A, spikes 10 can be driven quickly into the bale, for example over a period of about 5 to 10 seconds until plate 12 abuts against the bale. The displacement means, as shown in FIG. 4B can be actuated during the entire 5 to 10 seconds to inject fluid through the thickness of the bale. The spikes are then removed from the bale. Any volume of fluid can be injected by adjusting the stop or collar on the ram. In one embodiment, a displacement means having a chamber volume of 81/2 gallons is used and the ram stop is adjusted to deliver 5 gallons of liquid into a bale over a delivery of 8 seconds. It will be apparent that many changes may be made to the illustrative embodiments, while falling within the scope of the invention and it is intended that all such changes be covered by the claims appended hereto.
A device for and method of injecting a bale of ruminant material with a fluid is taught. The device includes a plurality of injection spikes for insertion into the bale. The spikes are attached to a support for supporting the spikes while they are inserted into the bale. The spikes are attached to the support by a resilient member. The device prevents the deformation of the spikes and thereby increases the useable life of the device over devices in which the spikes are rigidly mounted on a driving structure. The device further has injection drive which allows precise control over the amount of fluid being injected into the bale.
Briefly outline the background technology and the problem the invention aims to solve.
[ "FIELD OF THE INVENTION The present invention is directed toward a device for and method of injecting a fluid into a bale of forage materials.", "BACKGROUND OF THE INVENTION Animals are fed grains, forage feed stuffs for roughage, such as hay and/or straw, and liquid nutrient supplements.", "A convenient means of administering the liquid nutrient supplements has been to spray or pour the liquid onto the forage feed stuffs before distributing it to the animal feeding areas.", "This process of spraying or pouring, however, is inconvenient, labour intensive and imprecise.", "Often nutrients are wasted and more than the required amount is added to compensate for the amounts which are wasted.", "A method is required for applying liquid nutrients to a feed bale which prevents waste and can be carried out at a convenient time, such as during the bale handling at harvest or just prior to distribution to animals.", "Devices for injecting fluid into feed bales are known as described by U.S. Pat. No. 4,606,172 issued August 1986 to Miller.", "The prior device has a plurality of spikes for driving into the bale to deliver ammonia therethrough into the bale.", "An injection device is required which is able to accommodate the forces imparted to the injection spikes during insertion into the bale.", "An injection device is also required which can be used to control precisely the amount of fluid inserted into the bale.", "SUMMARY OF THE INVENTION A device for injecting a bale with a fluid through a hollow spike or spikes is disclosed which is able to accommodate the forces imparted on the spikes during driving into the bale.", "A device is also taught which can be adjusted to inject a selected amount of fluid into the bale without continuous monitoring of the volume being injected.", "In accordance with a broad aspect of the present invention, there is provided a device for injecting a fluid into a bale comprising: at least one injection spike having passage therethrough;", "a frame for supporting the spike;", "a resilient member attached between the spike and the frame and securing the spike to the frame;", "and a fluid feed system for injecting a fluid from a fluid source through the passage.", "In accordance with another aspect of the present invention, there is provided a device for injecting a fluid into a bale comprising: at least one injection spike having a passage therethrough;", "a frame for supporting the spike;", "and a fluid feed system for injecting a fluid from a fluid source through the passage including a fluid displacement chamber and means to displace a selected amount of fluid from the system through the passage.", "A method for injecting a fluid into a bale is also disclosed.", "In accordance with a broad aspect of the present invention there is provided a method for injecting a fluid into a bale comprising: providing a device including at least one injection spike having a passage therethrough, a frame for supporting the spike, and a fluid feed system for injecting a fluid from a fluid source through the passage including a fluid displacement chamber and means to displace a selected amount of fluid from the system through the passage.", "In a preferred embodiment, the fluid feed system for displacing a selected amount of the fluid from the system includes a fluid displacement means having a housing defining an internal chamber, a one way inlet to the chamber and a one way outlet from the chamber, the chamber containing a piston driven to sweep a selected volume of the chamber to displace a selected volume of fluid from the chamber;", "selecting the internal volume which is to be swept by the piston;", "inserting the spike into the bale;", "and actuating the fluid displacement chamber to displace the selected volume of fluid into the bale.", "Thus, in accordance with a further broad aspect of the present invention, there is provided a method for injecting liquid nutrient supplements to a bale comprising: providing a bale;", "piercing the bale with a hollow spike;", "and inserting liquid nutrient into the interior of the bale through the hollow spike.", "In one embodiment this is accomplished using a device including at least one injection spike having an internal passage therethrough, a frame for supporting the spike and means for injecting liquid nutrients from a liquid source through the internal passage of the spike.", "BRIEF DESCRIPTION OF THE INVENTION The device of the present invention is useful for all types of bales which are prepared in a way that permits insertion of a spike therein.", "The device includes at least one injection spike having a passage therethrough, a frame for supporting the spike and a fluid feed system for injecting a fluid from a fluid source through the passage of the spike.", "In one embodiment of the invention, the spike of the device is sized to be easily inserted into a bale and is preferably slender and elongate having a tapered tip at its outer end.", "The spike preferably is sized to extend generally to the centre of the bale and has a diameter such that a hole does not remain in the bale after removal of the spike from the bale.", "This prevents the formation after removal of the spike of an opening in the bale through which the injected fluid can leak from the bale.", "The spike is formed of a durable material such as, for example, stainless steel.", "The spike is supported by a frame.", "The frame can take any suitable form.", "In one embodiment it is a plate member.", "In another embodiment, the frame is formed as a pair of facing arms which are moveable to approach the bale on opposite sides.", "The frame can be modified in any desired way to facilitate insertion of the spike into a bale and to support the spike against the forces inherent in such insertion.", "The frame can also be modified to permit it to be mounted on a farm machine for transport.", "In one embodiment of the invention, a device is provided wherein a resilient member is disposed between the spike and the frame.", "The resilient member acts to secure the spike to extend out from the frame in a selected orientation, but permits the spike to be moved out of that selected orientation by application of a selected minimum force to the spike.", "By action of the resilient member, the spike will return to substantially its selected orientation when selected minimum the force is removed.", "The resilient member reduces deformation and shearing of the spike and, therefore, extends the useable life of the spike and the device.", "The resilient member can be any suitable member such as a spring or an elastomeric material.", "The device further includes a fluid feed system for injecting a fluid from a fluid source through the passage of the spike.", "The system can be any suitable system for injection of fluids and can include for, example pumps, valves, fluid conduit and seals.", "In one embodiment, the fluid feed system includes a fluid displacement means.", "The fluid displacement means includes a chamber having an internal piston driven by a ram.", "A stop on the ram determines the internal chamber volume which is swept by the piston and therefore, the amount of fluid which is displaced from the chamber by the piston during the stroke of the piston.", "Preferably, the stop can be adjustable along the ram to select the chamber volume which is swept by the piston.", "The device of the present invention can be used to inject a fluid into a bale.", "In a preferred method, liquid nutrient supplements are injected into a feed bale.", "Liquid nutrient supplements are known and contain various formulations of proteins, vitamins, minerals and carbohydrates.", "Preferably, the liquid nutrients are injected into straw bales according to the method of the present invention.", "This causes the straw, which is normally not readily consumed by cattle, to be more palatable to the cattle and to have greater nutritional content.", "In one embodiment, the method provides that a selected volume of nutrients is injected to the bale and fed to the animals with the bale.", "This can be done after formation of the bale before storing the bale or, preferably, just prior to feeding the bale to the animals.", "Injection of the nutrient just prior to feeding avoids breakdown of the nutrients and permits adjustment of the amount injected depending on feed requirements at the time.", "BRIEF DESCRIPTION OF THE DRAWINGS A further, detailed, description of the invention, briefly described above, will follow by reference to the following drawings of specific embodiments of the invention, which depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope.", "In the drawings: FIG. 1 is a perspective view of an injection device according to the present invention with the frame partially cut away;", "FIG. 2 is a sectional view of an injection spike useful in the present invention;", "FIG. 3A is a front elevation view of another embodiment of an injection device according to the present invention;", "FIG. 3B is a perspective view of a bale stabilizer attachment useful in the embodiment of FIG. 3A shown attached to a frame bar;", "FIG. 4A is a schematic view of a fluid flow system useful in the present invention;", "FIG. 4B is a front elevational view of a fluid displacement chamber useful in the present invention with the housing shown cut away;", "and FIG. 4C is a sectional view through line 4C--4C of FIG. 4B.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, a device according to the present invention is shown having a plurality of spikes 10 supported by a frame formed as a plate 12.", "The device shown in FIG. 1 is intended for use to inject fluids into a circular bale, thus the spikes 10 are spaced on plate 12 so as to penetrate the central area of such a bale.", "In particular, a circular bale generally has a diameter of between about 4 to 6 feet.", "Thus, spikes 10 are spaced about an area having a diameter of about 47 inches.", "Preferably, the plate is circular in plan view having a diameter of 48 inches.", "The plate is preferably formed of steel.", "Each spike is preferably slender and elongate to facilitate insertion into a bale.", "Preferably also, the spikes are tapered at their outer ends 10".", "The spikes are selected such that their ends 10"", "extend a suitable distance into the bale.", "For example, in a preferred embodiment for use with a circular bale having a length of about 4 to 5 feet, the probes are selected to be about 22 inches in length.", "Preferably, the spikes are selected such that when they are removed from a bale, a wound will not be left in the bale.", "For example, in a preferred embodiment the spike has a diameter of less than about 1 inch and preferably has a 1/2 inch outer diameter.", "Preferably, the spikes are formed of a strong durable material, such as for example stainless steel tubing.", "Each spike 10 is threaded at its inner end 10'", "and is engaged in a threaded bore 14 of a coupler 15.", "Coupler 15 is retained, such as by welding, in a coil spring 16 which is secured to plate 12, such as by welding.", "Spring 16 normally maintains spike 10 in a position substantially perpendicular to plate 12.", "Application of a force which is sufficient to overcome the tension in spring 16 will move spike 10 out of the perpendicular position and also provides that the spike will return to the substantially perpendicular position, when the force is removed.", "The spring can be replaced by any resilient member which provides for such movement.", "Preferably, the spring is selected to permit the spike to be moved out of its substantially perpendicular position by application of a force of between 20 and 80 pounds of pressure (psig) perpendicular to the long axis of the spike at its tip and preferably 50 pounds of pressure.", "Preferably, the spring is a heavy gauge coil spring welded to a washer 18 which is in turn welded to plate 12.", "When the plate 12 and spike 10 are of the dimensions stated above as being preferred, the coil spring is preferably a 2 inch OD, 1 3/4 inch ID and 2 1/2-3 inch long steel coil spring having a tensile strength of 200,000 psi.", "Each spike 10 has a passage 10a therethrough.", "Passage 10a extends axially through spike 10 and is in communication at its inlet end with bore 14 of threaded coupler 15.", "The outlet end of each passage 10a communicates with at least one exit port 30 in the spike adjacent its outer end.", "A fluid-tight seal is provided at each point of connection such as for example by hydraulic line coupling means or o-rings (not shown).", "Plate 12 has apertures 20 formed therethrough for passage of fluid lines 22 which extend between bore 14 of coupler 15 and a fluid distribution chamber 24 (FIG.", "4a), mounted on the rear side of plate 12.", "Fluid lines 22 provide a fluid-tight conduit from chamber 24 to coupler 15.", "Connections are sealed by any suitable means against passage of fluids.", "A fluid feed circuit is set up whereby a fluid source such as a supply tank (80 in FIG. 4A) is in fluid communication with exit ports 30 of the spikes 10 by conduit means including distribution chamber 24, feed lines 22, bore 14 and spike passage 10a.", "A suitable regulator is provided for regulating the flow of fluid from the fluid source through the conduits and passaging for injection into a bale impaled on spikes 10.", "In a preferred embodiment as shown in FIG. 2, a ball valve 31 is mounted at the outer end of each spike between passage 10a and exit port 30 to regulate the flow of fluid from the spikes.", "Valve 31 comprises a housing 32 having an inner chamber 34, with at least one exit port 30 extending through the housing in communication with the inner chamber.", "Preferably, housing 32 has a tapered tip 35 to facilitate insertion into a bale.", "Preferably, tip 35 is threadably engaged to housing 32 so that tip 35 can be replaced without replacing the entire housing.", "Valve 31 is preferably secured to spike 10 by threading at 36 which facilitates repair or replacement.", "A ball 40 is seated against the outlet opening 42 of passage 10a and is maintained in position by a spring 44 acting between an end wall 46 of inner chamber 34 and ball 40.", "Ball 40 will normally provide a fluid-tight seal against opening 42 unless fluid flows at a pressure sufficient to overcome the tension in spring 44 to move ball 40 away from opening 42.", "The tension in spring 44 can be adjusted by tightening tip 35 onto housing 32.", "Preferably, the valve is selected to be opened by fluid at 30 pounds pressure.", "Another embodiment of the device is shown in FIGS. 3A and 3B.", "The device has a frame 50 having mounted thereon a mounting attachment 52 for connection to a cherry picker implement arm 53.", "Mounting attachments for cherry pickers are known and will not be described herein.", "Any other mounting attachment can be used for transport of the device by another farm implement.", "In the preferred embodiment, however, the frame is attached to an implement which provides for vertical movement of the device.", "Frame 50 includes a top bar 56 carrying a pair of spaced, downwardly extending arms 58, 59 at the outer ends of which spiked plates 60 are mounted.", "FIG. 3A shows the arms in open position aligned for movement towards each other and insertion into bale 62 positioned on a ground surface 63.", "Spiked plates 60 each include plate 12 and spikes 10 and are preferably as described in relation to plate 12 of FIG. 1 and having spikes and spike mounting arrangements as described in relation to FIG. 2. Top bar 56 has formed thereon or attached thereto roller tracks 64 to accept and retain roller wheels 65 (shown in phantom) secured onto arms 58, 59 by brackets 66 and pins 67.", "Roller wheels 65 are free to ride along tracks 64 and thereby move arms 58, 59 along bar 56.", "To drive the movement of the arms along the bar, hydraulic cylinders 68, 69 extend between arms 58, 59, respectively and a central mounting flange 70 on bar 56.", "Preferably, cylinders 68, 69 are calibrated, as is known, to drive arms 58, 59 at the same rate and cylinders 68, 69 are connected by a line 71 extending between them.", "Cylinders 68, 69 are further connected by lines 72 to a hydraulic fluid source and a standard control mechanism.", "The action of the cylinders is controlled by an operator through the control mechanism.", "Instead of the roller track and hydraulics arrangement as shown, the movement of the arms relative to each other can be driven by any other suitable drive means.", "Fluid feed lines 74 lead from a fluid source (not shown) to spiked plates 60.", "Lines are formed preferably of hydraulic hose, rubber hose and/or tubing.", "A bale stabilizing means depends downwardly from bar 56 intermediate arms 58, 59.", "The means includes a pair of arms 76 each having positioned at its lower end a stop plate 77 for abutting against a bale to be injected.", "Bale stabilizing spikes 78 (FIG.", "3B) extend from stop plates 77.", "A bar 79 extends between the stop plates to strengthen the arrangement.", "It is to be understood that any number of arms will work.", "For example, the pair of arms shown can be replaced by one which is located substantially centrally.", "The length of arm 76 is preferably selected relative to the distance of the spiked plate 60 from bar 56 such that when stop plate 78 rests on the bale, the spikes are positioned for entry into the bale.", "Preferably, the length of the arm 76 is selected such that spikes 10 are positioned centrally relative to the bale, in preparation for insertion into the bale.", "Referring to FIGS. 4A, 4B and 4C, a fluid feed system useful in the present invention comprises a fluid source 80, a line 82 leading from source 80 to a fluid displacement means 84, line 74 leading from means 84 to fluid distribution chamber 24 and lines 22 leading to the passages of spikes 10.", "The fluid feed system is formed to be substantially fluid-tight preferably to contain internal fluid pressures of between about 25 to 80 pounds pressure.", "The fluid source can be, for example, a tank carried on a farm implement.", "Lines 82, 74, 22 can be formed from any suitable fluid-tight materials such as hydraulic lines or tubing.", "All connections are fluid-tight.", "Fluid distribution chamber 24 can be formed in any suitable way for distribution of fluids under pressure to lines 22.", "Preferably, chamber 24 is mounted on plate 12 and is formed by four 4"×4"", "tubes 86 extending from a central hub 88.", "Fluid displacement means 84 includes a housing 89 which defines a cylindrical chamber 89a.", "Preferably, housing 89 is formed from hydraulic cylinder tubing having a polished inner surface.", "The cylindrical chamber 89a is selected to have a volume corresponding to the range of volumes which is desired to be injected using the device.", "Leading into the chamber, according to the direction of fluid flow, is an inlet line 90 with a one-way check valve 91.", "Valve 91 is selected to permit fluid flow in a direction, indicated by arrow A, into chamber 89a and to block flow in an opposite direction.", "Leading away from the chamber is outlet line 92 with a second one-way check valve 93.", "The second valve 93 is selected to permit fluid flow in a direction, indicated by arrow B, out of chamber 89a and to block flow in an opposite direction.", "A piston 94 is contained in chamber 89a and is connected to a ram 95.", "Ram 95 is driven by a hydraulic cylinder 96.", "When ram 95 is driven by cylinder 96, piston 94 is moved within chamber 89a.", "Piston 94 is selected to form a fluid tight seal against the inner cylindrical surface of the housing.", "In one embodiment in which liquid is injected, the piston has a first plate 105, a second plate 107 and sandwiched therebetween a rubber sheet 109.", "Plates 105 and 107 have a slightly smaller diameter than the chamber diameter.", "Rubber sheet 109 has slightly larger diameter than the diameter of the chamber and a thickness of about 1/2 inch.", "Ram 95 is attached to plate 107.", "Bolts 111 are welded onto plate 105 and extend through apertures in rubber sheet 109 and plate 107 where nuts 113 are threadably engaged onto bolts 111.", "To adjust the seal of the piston against the inner surface of the chamber, nuts 113 can be tightened on bolts 111 to force plates 105 and 107 closer together and to urge rubber sheet 109 to be expanded outwardly.", "When the system, and thereby the displacement means, is fully charged with fluid, any movement of piston 94 within chamber 89a, will cause a flow of fluid through the system.", "In particular, when the ram and, thereby, the piston are driven by cylinder 96 in the direction indicated by arrow c, fluid will be drawn from fluid source 80 through check valve 91 into chamber 89a and when the ram and the piston are driven by the cylinder in the direction indicated by arrow d, fluid will be forced from the chamber through valve 93 out through the exit ports 30 in spikes 10.", "The volume of chamber 89a which is swept by piston 94 is selected to correspond with the volume of fluid which is to be injected into the bale.", "To select the volume of the chamber which is swept by the piston from the position in which the ram is most withdrawn from the chamber, preferably, a stop 98 is securely positioned by a lock pin 98a on ram 95 to limit the extent to which the ram can be driven along chamber 89a.", "The stop can abut against housing 89 or, alternately, as shown, the stop can abut against a collar 99 secured about the ram by screws 100 between the stop and the housing.", "The collar is selected to have a shape or minimum internal diameter to prevent the stop from passing beneath it.", "To select the volume which is swept by the piston, the collar can be replaced with a collar having a different length.", "Preferably, a set of collars are provided having different lengths and are marked to indicated which volume of fluid will be displaced using any selected collar.", "Alternately or in addition, to select the volume which is swept by a piston stroke, the stop can be locked using pin 98a into a selected position along the ram.", "Preferably, the ram is marked with calibrations 101 to indicate the volume at any stop location along the ram.", "In use, the device is positioned relative to a bale such that the spikes are aligned for insertion into the bale.", "The spikes are then driven into the bale and fluid is injected therethrough.", "Using the device of FIG. 3A, spikes 10 can be driven quickly into the bale, for example over a period of about 5 to 10 seconds until plate 12 abuts against the bale.", "The displacement means, as shown in FIG. 4B can be actuated during the entire 5 to 10 seconds to inject fluid through the thickness of the bale.", "The spikes are then removed from the bale.", "Any volume of fluid can be injected by adjusting the stop or collar on the ram.", "In one embodiment, a displacement means having a chamber volume of 81/2 gallons is used and the ram stop is adjusted to deliver 5 gallons of liquid into a bale over a delivery of 8 seconds.", "It will be apparent that many changes may be made to the illustrative embodiments, while falling within the scope of the invention and it is intended that all such changes be covered by the claims appended hereto." ]
CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application claims the benefit under 35 USC §119(e) of U.S. Provisional Patent Application Ser. No. 61/226,918 to Popa et al., filed Jul. 20, 2009, hereby incorporated by reference herein. FIELD OF THE INVENTION [0002] The present invention relates generally to an environment for distributing satellite signals to set top boxes and, more particularly, to methods and systems for achieving improved signal security in such an environment. BACKGROUND [0003] Improving the security of a satellite signal is a continuous challenge for signal distributors. The lack of a native two-way communication channel between receiver and head end leaves the satellite signal vulnerable to piracy. In one type of attack, a subscribing customer activates multiple receivers under one account and passes them along to friends and neighbors for a nominal fee that is less than what would be charged by the satellite distributor if each friend or neighbor were to establish their own individual account. Another form of piracy arises when a subscribing customer retrieves a security code from a legitimate receiver, and distributes the code to non-subscribing owners of other receivers through another communication medium (usually the Internet). [0004] Clearly, such breaches of security can have an impact on revenues and therefore improvements in the area of protecting satellite signals from piracy would be welcomed by the satellite signal distribution industry. SUMMARY [0005] A first broad aspect of the present invention seeks to provide a method implemented by a set top box, the method comprising: obtaining a security data element; obtaining data for a channel stacking switch; combining the security data element with the data to formulate a message for the channel stacking switch; releasing the message towards the channel stacking switch. [0006] A second broad aspect of the present invention seeks to provide a set top box, comprising: a processing entity configured to obtain data for a channel stacking switch, to obtain a security data element and to formulate a message for the channel stacking switch by combining the security data element with the data; a communications interface configured to send the message to channel stacking switch. [0007] A third broad aspect of the present invention seeks to provide a computer-readable storage medium storing instructions for execution by a set top box (STB), wherein execution of the instructions by the STB causes the STB to: obtain a security data element; obtain data for a channel stacking switch; combine the security data element with the data to formulate a message for the channel stacking switch; release the message towards the channel stacking switch. [0008] A fourth broad aspect of the present invention seeks to provide a method implemented by a channel stacking switch (CSS), comprising: receiving a message from a set top box over a communications link; processing the message to determine whether or not the message is legitimate; taking an action that depends on whether or not the message is legitimate. [0009] A fifth broad aspect of the present invention seeks to provide a channel stacking switch, comprising: a communication interface configured to receive a message from a set top box; a processing entity configured to determine whether or not the message is legitimate and to take an action that depends on whether or not the message is legitimate. [0010] A sixth broad aspect of the present invention seeks to provide a computer-readable storage medium storing instructions for execution by a channel stacking switch (CSS), wherein execution of the instructions by the CSS causes the CSS to: be attentive to receipt of a message from a set top box over a communications link; process the message to determine whether or not the message is legitimate; take an action that depends on whether or not the message is legitimate. [0011] A seventh broad aspect of the present invention seeks to provide a satellite signal receiving system comprising a channel stacking switch and at least one set top box in secure communication with the channel stacking switch. [0012] These and other aspects and features of the present invention will now become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0013] In the accompanying drawings: [0014] FIG. 1 is a block diagram of a satellite signal distribution environment involving a channel stacking switch and a set top box. [0015] FIG. 2 is a spectral diagram showing a wideband satellite signal containing a desired satellite transponder channel to be isolated by the channel stacking switch on request from the set top box. [0016] FIG. 3 is a signal flow diagram showing a protocol for securing a channel between the channel stacking switch and the set top box, in accordance with a specific non-limiting embodiment of the present invention. [0017] FIGS. 4-6 are flow diagrams showing three non-limiting alternative approaches by virtue of which the set top box obtains a security data element for transmission to the channel stacking switch as part of the protocol of FIG. 3 . [0018] It is to be expressly understood that the description and drawings are only for the purpose of illustration of certain embodiments of the invention and are an aid for understanding. They are not intended to be a definition of the limits of the invention. DESCRIPTION [0019] Embodiments of the present invention propose a solution for securing part of the communication channel between the head end and the user receiver (set top box—STB). This solution is based on the intelligence provided by the STB and an outdoor unit (ODU), in particular a Channel Stacking Switch (CSS). CSS technology reduces STB installation costs and complexity, by requiring only one cable drop per STB, even if the receiver (i.e., the STB) has multiple tuners. The interested reader can find more information about channel stacking switches and their applications in the document entitled “Channel Stacking Switch Technology for Residential DBS Reduces Cabling and STBs”, by M. Ploof, P. Wong and T. Brandon, EE Times-India (www.eetindia.com), November 2007. This document is hereby incorporated herein by reference. [0020] Generally speaking, the CSS provides a plurality of User Bands (UBs) between itself and one or more set top boxes. A single-tuner STB is assigned one of the user bands and a dual-tuner STB is assigned two of the user bands. The use of a CSS to distribute satellite signals to a group of set top boxes thus becomes an economical choice when upgrades are envisaged, such as in a single family home when multiple viewing areas are required, and in multi-dwelling units (MDUs). [0021] The term “set top box” is not intended to be limited to a particular hardware configuration, but rather is meant to encompass receivers that are capable of processing a signal received from an external source for delivery to a display set for conveyance to a user. The term “processing” is meant to encompass one or more of filtering, decoding, descrambling, demultiplexing and downconverting the received signal. The display set can include a television set, a computer monitor and/or a mobile device, to name a few non-limiting possibilities. [0022] Reference is made to FIG. 1 , which shows a satellite signal distribution environment. In the illustrated environment, a set top box (STB) 102 communicates over a communications link 104 (e.g., a cable) with an outdoor unit, in this case illustrated as a Channel Stacking Switch (CSS) 106 . To this end, the CSS 106 and the STB 102 each have a respective communications interface and a respective processing entity (e.g., a controller running software or firmware). Although FIG. 1 illustrates a single set top box (STB 102 ), it should be understood that in practice, multiple set top boxes can be made to share access to the communications link 104 by cable splitting (i.e., physically and electrically interconnecting them in parallel) or by using other access architectures, which may or may not utilize switching nodes. [0023] In a specific non-limiting example, communication between the CSS 106 and the STB 102 may take place in accordance with EUTELSAT DiSEqC 2.0 Bus Specification v. 4.2, which describes a two way communication protocol between a satellite STB and an outdoor unit (ODU). The DiSEqC 2.0 Bus Specification v. 4.2 is mentioned because it allows extensions that would implement additional functionality required by a specific application. However, it should be appreciated that other versions of the DiSEqC specification, as well as other protocols, including proprietary ones, can be used without departing from the scope of the present invention. [0024] The communications link 104 supports communication over a frequency range that may be L-band (950 MHz to 2150 MHz), without being limited thereto. This frequency range is divided into “user bands”. One of these user bands is assigned to the STB 102 (or in the case of a multi-tuner set top box, several user bands may be assigned to the STB 102 but each such user band is uniquely assigned to each tuner). A reverse channel may also exist to permit upstream communication (i.e., from the STB 102 to the CSS 106 ). In various embodiments, the reverse channel may be a separate frequency channel, a tone that is modulated, etc. A separate cable may also be used for the reverse channel. [0025] The STB 102 includes a memory 103 (e.g., flash memory or any other type of non-volatile storage media) that indicates its assigned user band, thus allowing the STB 102 to utilize the correct central frequency when receiving signals from the CSS 106 along the communications link 104 . The memory 103 also stores an identifier of the STB 102 such as an IRD or a serial number (where a multi-tuner STB is concerned, an extension may be provided for uniquely identifying each tuner). Other ways of identifying the STB 102 are of course possible, including various forms of codes and addresses. Other data may also be stored in the memory 103 as will become apparent from the description to follow. [0026] The CSS 106 includes or has access to a memory 107 (e.g., flash memory or any other type of non-volatile storage media) in which it stores the assignment of user bands to set top boxes including the STB 102 . For example, the STB 102 may be identified by its IRD, serial number or other identifier mentioned above, while the assigned user band may be identified by its center frequency or by an index or other code. The memory 107 also stores an identifier of the CSS 106 , such as a serial number, hardware identifier (HWI), or other form of identifier. Other data may also be stored in the memory 107 as will become apparent from the description to follow. The memory 107 may be part of the CSS 106 or accessible thereto via a data network such as the Internet. [0027] The STB 102 is connected to a display set viewed by a viewer. The display set could be a television set, computer monitor, wireless communication device or a device implementing a combination of the aforementioned functionalities. The STB 102 performs video decoding and other functions, including receiving an indication of the channel that the viewer wants to watch. In particular, over time, the STB 102 generates tuning requests based on channels identified by the viewer. Specifically, a channel identified by the viewer (e.g., via a remote control device or by pressing a button on the display set) is mapped to a desired satellite transponder channel by the STB 102 . The desired satellite transponder channel is identified in a tuning request sent to the CSS 106 over the communications link 104 in accordance with a format, which can be the DiSEgC™ format (without being limited thereto). The tuning request can be sent over the reverse channel (e.g., using a separate frequency band reserved for upstream communication, one or more DiSEgC™ tone frequencies, a separate cable, etc.) from the STB 102 to the CSS 106 . [0028] The CSS 106 is responsible for receiving tuning requests from the STB 102 (and other set top boxes, if applicable) and processing the requests. Specifically, the CSS 106 determines where in the satellite frequency range the desired satellite transponder channel is located. A mapping (e.g., in the memory 107 ) could be consulted to this effect in order to identify a target wideband satellite frequency range. Then, the CSS 106 provides a satellite feed unit 108 (e.g., a low noise block downconverter 110 connected to a satellite dish 112 ) with a control signal. With additional reference to FIG. 2 , the control signal allows the satellite feed unit 108 to admit a wideband satellite signal 202 to the CSS 106 , such signal occupying the target wideband satellite frequency range. Examples of parameters that can be controlled by the CSS 106 include the polarization and frequency range of the admitted wideband satellite signal 202 . Further information regarding an example manner of controlling a low noise block downconverter can be found in the document entitled “Low Noise Block Downconverter” from Satellite Signals Limited, available at www.satsig.net/Inb/explanation-description-Inb.htm. This document is hereby incorporated by reference herein. [0029] Next, the CSS 106 isolates the desired satellite transponder channel 204 within the wideband satellite signal 202 . This can be done by translating in the frequency domain the desired satellite transponder channel 204 to the user band (i.e., the tuner central frequency) assigned to the STB 102 that originated the tuning request. A surface acoustic wave (SAW) filter can be used for this purpose. The resulting signal, denoted 206 , is sent to the STB 102 . The signal 206 can be “stacked” (i.e., frequency multiplexed) with other signals in other user bands destined for other set top boxes. These are all sent together and each individual STB will know which signal to consider, based on its own user band, which is uniquely assigned. [0030] Thus, it will be appreciated that the tuner in the STB 102 does not need to change its central frequency during normal operation. Rather, it is the CSS 106 that takes over the tuning function, mapping a desired satellite transponder channel to the tuner's central frequency. [0031] In accordance with a specific non-limiting embodiment of the present invention, a securitization protocol is provided for securing communication between the CSS 106 and the STB 102 . [0032] With reference to FIG. 3 , at step 302 , the STB 102 receives a trigger 350 . In one embodiment, the trigger 350 can be sent when the head end 102 wishes to secure communications between the CSS 106 and the STB 102 . In this case, the STB 102 receives the trigger 350 via the satellite dish 112 , the low noise block downconverter 110 , the CSS 106 and the communications link 104 . In another embodiment, the trigger 350 can be sent under control of the CSS 106 . The trigger 350 can be issued by the appropriate entity a single time, periodically, after every cold boot, or generally at any arbitrary time instant or instants. In another embodiment, which may be less secure, the trigger 350 can be generated by the STB 102 itself, either autonomously or based on input received from the viewer. [0033] At step 304 , in response to having received the trigger 350 at step 302 , the STB 102 obtains a security data element 360 . The security data element 360 may take on various forms and may be obtained in various ways, several of which are described later on in greater detail. [0034] At step 306 , the STB 102 combines the security data element 360 with data destined for the CSS 106 (such as a tuning request) to formulate a message 370 . Combining can include appending the security data element 360 to the data, encrypting the data with the security data element 360 , etc., as will be described herein below in greater detail. Message 370 is sent to the CSS 106 over the reverse channel (e.g., using a separate frequency band reserved for upstream communication, one or more DiSEgC™ tone frequencies, a separate cable, etc.). [0035] From the perspective of the CSS 106 , it cannot know a priori whether or not any given received message from any given set top box (such as message 370 from the STB 102 ) is indeed legitimate. Therefore, at step 308 , upon receipt of message 370 from the STB 102 , the CSS 106 verifies its legitimacy in one of several possible ways, each of which involves consulting the memory 107 , and some of which are described below in greater detail. A received message that will have been formulated based on combining data destined for the CSS 106 with the security data element 360 will be considered “legitimate” by the CSS 106 , as will be described later on. [0036] At step 310 , the CSS 106 takes an action depending on whether or not the received message (in this case message 370 ) was determined to be legitimate at step 308 . [0037] For example, if the received message (in this case message 370 ) was found to be legitimate at step 308 and included a tuning request (which may specify a desired satellite transponder channel), the action taken at step 310 can comprise serving the tuning request on behalf of the STB 102 . This can include controlling the low noise block downconverter 110 so as to admit a wideband satellite signal from an ambient signal received at the satellite dish 112 , isolating the desired satellite transponder channel from the wideband satellite signal and frequency translating the desired satellite transponder channel into the user band assigned to the STB 102 . [0038] On the other hand, if the received message (in this case message 370 ) was found not to be legitimate at step 308 , then the action taken at step 310 can comprise returning an error message to the STB 102 in its assigned user band, in response to which the STB 102 can display (or otherwise convey) an error message perceptible by the viewer. [0039] As mentioned above, the security data element 360 may take on various forms in different embodiments, with corresponding differences in the manner in which it is combined with data to formulate messages (such as message 370 ) sent to the CSS 106 and also differences in the manner in which the CSS 106 verifies a received message's legitimacy. The following non-limiting example scenarios offer different levels of security with different levels of implementational complexity. It should also be appreciated that other security scenarios are possible. [0040] In a first example security scenario, the security data element 360 is a key obtained from the CSS 106 . The key may take the form of an identifier of the CSS 106 or other data known to the CSS 106 . Specifically, with reference to FIG. 4 , the STB 102 issues a key request message 402 to the CSS 106 . The CSS 106 accesses the memory 107 and extracts an identifier 404 of the CSS 106 (e.g., the HWI). The CSS 106 then issues a response message 406 to the STB 102 containing the identifier 404 . At the STB 102 , the identifier 404 received from the CSS 106 is stored in the memory 103 as the security data element 360 . [0041] Thus, combining the security data element 360 with data (e.g., a tuning request) destined for the CSS 106 in order to formulate message 370 (as mentioned at step 306 ) comprises the STB 102 encrypting such data with the identifier 404 using any desired technique for symmetric encryption, i.e., in such a way that the same identifier 404 can be used by the CSS 106 to successfully decrypt messages that have been encrypted. [0042] Accordingly, at step 308 , the “processing” carried out by the CSS 106 on message 370 is an attempt to decrypt message 370 using the identifier 404 that had previously been sent to the STB 102 which, if successful, will yield the data destined for the CSS 106 (e.g., a tuning request). [0043] In a second example security scenario, the security data element 360 is also a key obtained from the CSS 106 , except that the key is an encryption key used in asymmetric encryption. The encryption key may take the form of a public key forming part of a public-private key pair, with the corresponding private key being held secret in the memory 107 of the CSS 106 . With reference to FIG. 5 , the STB 102 issues a key request message 502 to the CSS 106 . The CSS 106 accesses the memory 107 and extracts a CSS public key 504 . The memory 107 also stores a complementary CSS private key 505 in association with the CSS public key 504 as part of a CSS key pair 507 . The CSS 106 then issues a response message 506 to the STB 102 containing the CSS public key 504 . At the STB 102 , the CSS public key 504 received from the CSS 106 is stored in the memory 103 as the security data element 360 . [0044] Thus, combining the security data element 360 with data destined for the CSS 106 (e.g., a tuning request) in order to formulate message 370 (as mentioned at step 306 ) comprises the STB 102 encrypting such data with the CSS public key 504 using any desired technique for asymmetric encryption, i.e., in such a way that successful decryption requires a complementary decryption key, in this case the CSS private key 505 . [0045] Accordingly, at step 308 , the processing carried out by the CSS 106 on message 370 is an attempt to decrypt message 370 using the CSS private key 505 stored in the memory 107 which, if successful, will yield the data destined for the CSS 106 (e.g., a tuning request). [0046] It will be appreciated that in the second example security scenario above, the CSS 106 always retains information that the STB 102 cannot access (in this case, the CSS private key 505 ), which enhances security relative to the first security scenario. However, there is more processing overhead required of the processors at the CSS 106 and the STB 102 . [0047] Several techniques can be applied to the second example security scenario in order to further enhance security. One security enhancement is to change the key pair over time. That is to say, a different CSS public key can be provided to the STB 102 at various times, e.g., periodically or for every N th message, where N can be as low as 1. To this end, the memory 107 at the CSS 106 may include a table containing a plurality of key pairs from which a new pair is selected when needed. It is also possible for the pairs to be indexed and for the CSS public keys in the table also to be indexed and previously stored in the memory 103 at the STB 102 . Thus, when a new key pair is selected (either by the CSS 106 or by the STB 102 ), a new index is selected without revealing the CSS public key. [0048] Another security enhancement is to encrypt the reverse channel. Specifically, the memory 103 at the STB 102 may store a STB public key and a complementary STB private key. The key request message 502 sent by the STB 102 can include the CSS public key, which is then used by the CSS 106 to encrypt the response message 506 containing the CSS public key 504 . The received (encrypted) response message 506 is then decrypted by the STB 102 using the STB private key to reveal the CSS public key 504 contained therein. In this way, only a set top box with access to the STB private key would be able to properly obtain the CSS public key 504 , which enhances security. [0049] A third example security scenario is a variant that requires very little in the way of computational overhead. Specifically, with reference to FIG. 6 , the memory 107 at the CSS 106 stores a list 602 of identifiers of set top boxes that are considered “authorized”. In an alternative embodiment, the list 602 contains identifiers of set top boxes that are considered “not authorized”. The list 602 of authorized set top boxes (or unauthorized set top boxes) can be updated over time by the head end 120 . [0050] Additionally, an identifier of the STB 102 , denoted 604 , is stored in the memory 103 at the STB 102 . In accordance with the third security scenario, the security data element 360 comprises the identifier 604 , and data sent to the CSS 106 (e.g., a tuning request) can be combined with the identifier 604 simply by appending the identifier 604 to such data. Thus, message 370 contains both the data destined for the CSS 106 and the identifier 604 . [0051] Accordingly, at step 308 , the processing carried out by the CSS 106 on message 370 containing the data destined for the CSS 106 includes extraction of the identifier 604 and comparison of the identifier 604 to the identifiers in the list 602 . If the identifier 604 appears on the list 602 and the list 602 contains identifiers of set top boxes that are considered authorized, then message 370 is considered legitimate, otherwise the message is considered not legitimate. On the other hand, if the identifier 604 appears on the list 602 and the list 602 contains identifiers of set top boxes that are considered not authorized, then message 370 would be considered not legitimate, otherwise the message would be considered legitimate. [0052] It should be appreciated that in the third example security scenario, the STB 102 does not require knowledge of information about the CSS 106 . In contrast, the CSS 106 needs to know which set top boxes are authorized (or not authorized). [0053] In view of the foregoing, it should be appreciated that if a new set top box is connected to the CSS 106 once the above securitization protocol has been executed, functionality of such new set top box will be impaired, because it does not have access to an appropriate security data element (e.g., the identifier 404 of the CSS 106 , the CSS public key 504 , the identifier of an authorized STB) that would allow it to formulate a legitimate message for the CSS 106 . In particular, this prevents pirated set top boxes from successfully communicating with the CSS 106 in order to carry out certain importnat functions such as channel changes. [0054] It will also be appreciated that even if the STB 102 is capable of formulating messages that are considered by the CSS 106 to be legitimate, it may still be necessary to overcome conventional security barriers that may exist before viewing of a television channel is allowed. Such additional security barriers may include the provision of conventional conditional access codes, smart cards and the like. [0055] Thus, it will be appreciated that embodiments of the present invention assist in combating piracy and improving signal integrity. As a result, revenue loss due to signal theft is reduced and confidence (by the content owners) in the satellite signal integrity is increased, with a potential positive impact on revenues. [0056] Those skilled in the art will appreciate that in some embodiments, the STB 102 and/or the CSS 106 may be implemented using one or more computing apparatuses that have access to a code memory which stores computer-readable program code (instructions) for operation of the one or more computing apparatuses. The computer-readable program code could be stored on a medium which is fixed, tangible and readable directly by the one or more computing apparatuses, (e.g., removable diskette, CD-ROM, ROM, fixed disk, USB drive), or the computer-readable program code could be stored remotely but transmittable to the one or more computing apparatuses via a modem or other interface device (e.g., a communications adapter) connected to a network (including, without limitation, the Internet) over a transmission medium, which may be either a non-wireless medium (e.g., optical or analog communications lines) or a wireless medium (e.g., microwave, infrared or other transmission schemes) or a combination thereof. In other embodiments, the STB 102 and/or the CSS 106 may be implemented using pre-programmed hardware or firmware elements (e.g., application specific integrated circuits (ASICs), electrically erasable programmable read-only memories (EEPROMs), flash memory, etc.), or other related components. [0057] Certain adaptations and modifications of the described embodiments can be made. Therefore, the above discussed embodiments are to be considered illustrative and not restrictive. Also it should be appreciated that additional elements that may be needed for operation of certain embodiments of the present invention have not been described or illustrated as they are assumed to be within the purview of the person of ordinary skill in the art. Moreover, certain embodiments of the present invention may be free of, may lack and/or may function without any element that is not specifically disclosed herein.
Certain embodiments provide a set top box, comprising: a processing entity configured to obtain data for a channel stacking switch, to obtain a security data element and to formulate a message for the channel stacking switch by combining the security data element with the data; a communications interface configured to send the message to channel stacking switch. Other embodiments provide a channel stacking switch, comprising: a communication interface configured to receive a message from a set top box; a processing entity configured to determine whether or not the message is legitimate and to take an action that depends on whether or not the message is legitimate. Still further embodiments provide a satellite signal receiving system comprising a channel stacking switch and at least one set top box in secure communication with the channel stacking switch.
Briefly describe the main idea outlined in the provided context.
[ "CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application claims the benefit under 35 USC §119(e) of U.S. Provisional Patent Application Ser.", "No. 61/226,918 to Popa et al.", ", filed Jul. 20, 2009, hereby incorporated by reference herein.", "FIELD OF THE INVENTION [0002] The present invention relates generally to an environment for distributing satellite signals to set top boxes and, more particularly, to methods and systems for achieving improved signal security in such an environment.", "BACKGROUND [0003] Improving the security of a satellite signal is a continuous challenge for signal distributors.", "The lack of a native two-way communication channel between receiver and head end leaves the satellite signal vulnerable to piracy.", "In one type of attack, a subscribing customer activates multiple receivers under one account and passes them along to friends and neighbors for a nominal fee that is less than what would be charged by the satellite distributor if each friend or neighbor were to establish their own individual account.", "Another form of piracy arises when a subscribing customer retrieves a security code from a legitimate receiver, and distributes the code to non-subscribing owners of other receivers through another communication medium (usually the Internet).", "[0004] Clearly, such breaches of security can have an impact on revenues and therefore improvements in the area of protecting satellite signals from piracy would be welcomed by the satellite signal distribution industry.", "SUMMARY [0005] A first broad aspect of the present invention seeks to provide a method implemented by a set top box, the method comprising: obtaining a security data element;", "obtaining data for a channel stacking switch;", "combining the security data element with the data to formulate a message for the channel stacking switch;", "releasing the message towards the channel stacking switch.", "[0006] A second broad aspect of the present invention seeks to provide a set top box, comprising: a processing entity configured to obtain data for a channel stacking switch, to obtain a security data element and to formulate a message for the channel stacking switch by combining the security data element with the data;", "a communications interface configured to send the message to channel stacking switch.", "[0007] A third broad aspect of the present invention seeks to provide a computer-readable storage medium storing instructions for execution by a set top box (STB), wherein execution of the instructions by the STB causes the STB to: obtain a security data element;", "obtain data for a channel stacking switch;", "combine the security data element with the data to formulate a message for the channel stacking switch;", "release the message towards the channel stacking switch.", "[0008] A fourth broad aspect of the present invention seeks to provide a method implemented by a channel stacking switch (CSS), comprising: receiving a message from a set top box over a communications link;", "processing the message to determine whether or not the message is legitimate;", "taking an action that depends on whether or not the message is legitimate.", "[0009] A fifth broad aspect of the present invention seeks to provide a channel stacking switch, comprising: a communication interface configured to receive a message from a set top box;", "a processing entity configured to determine whether or not the message is legitimate and to take an action that depends on whether or not the message is legitimate.", "[0010] A sixth broad aspect of the present invention seeks to provide a computer-readable storage medium storing instructions for execution by a channel stacking switch (CSS), wherein execution of the instructions by the CSS causes the CSS to: be attentive to receipt of a message from a set top box over a communications link;", "process the message to determine whether or not the message is legitimate;", "take an action that depends on whether or not the message is legitimate.", "[0011] A seventh broad aspect of the present invention seeks to provide a satellite signal receiving system comprising a channel stacking switch and at least one set top box in secure communication with the channel stacking switch.", "[0012] These and other aspects and features of the present invention will now become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying drawings.", "BRIEF DESCRIPTION OF THE DRAWINGS [0013] In the accompanying drawings: [0014] FIG. 1 is a block diagram of a satellite signal distribution environment involving a channel stacking switch and a set top box.", "[0015] FIG. 2 is a spectral diagram showing a wideband satellite signal containing a desired satellite transponder channel to be isolated by the channel stacking switch on request from the set top box.", "[0016] FIG. 3 is a signal flow diagram showing a protocol for securing a channel between the channel stacking switch and the set top box, in accordance with a specific non-limiting embodiment of the present invention.", "[0017] FIGS. 4-6 are flow diagrams showing three non-limiting alternative approaches by virtue of which the set top box obtains a security data element for transmission to the channel stacking switch as part of the protocol of FIG. 3 .", "[0018] It is to be expressly understood that the description and drawings are only for the purpose of illustration of certain embodiments of the invention and are an aid for understanding.", "They are not intended to be a definition of the limits of the invention.", "DESCRIPTION [0019] Embodiments of the present invention propose a solution for securing part of the communication channel between the head end and the user receiver (set top box—STB).", "This solution is based on the intelligence provided by the STB and an outdoor unit (ODU), in particular a Channel Stacking Switch (CSS).", "CSS technology reduces STB installation costs and complexity, by requiring only one cable drop per STB, even if the receiver (i.e., the STB) has multiple tuners.", "The interested reader can find more information about channel stacking switches and their applications in the document entitled “Channel Stacking Switch Technology for Residential DBS Reduces Cabling and STBs”, by M. Ploof, P. Wong and T. Brandon, EE Times-India (www.", "eetindia.com), November 2007.", "This document is hereby incorporated herein by reference.", "[0020] Generally speaking, the CSS provides a plurality of User Bands (UBs) between itself and one or more set top boxes.", "A single-tuner STB is assigned one of the user bands and a dual-tuner STB is assigned two of the user bands.", "The use of a CSS to distribute satellite signals to a group of set top boxes thus becomes an economical choice when upgrades are envisaged, such as in a single family home when multiple viewing areas are required, and in multi-dwelling units (MDUs).", "[0021] The term “set top box”", "is not intended to be limited to a particular hardware configuration, but rather is meant to encompass receivers that are capable of processing a signal received from an external source for delivery to a display set for conveyance to a user.", "The term “processing”", "is meant to encompass one or more of filtering, decoding, descrambling, demultiplexing and downconverting the received signal.", "The display set can include a television set, a computer monitor and/or a mobile device, to name a few non-limiting possibilities.", "[0022] Reference is made to FIG. 1 , which shows a satellite signal distribution environment.", "In the illustrated environment, a set top box (STB) 102 communicates over a communications link 104 (e.g., a cable) with an outdoor unit, in this case illustrated as a Channel Stacking Switch (CSS) 106 .", "To this end, the CSS 106 and the STB 102 each have a respective communications interface and a respective processing entity (e.g., a controller running software or firmware).", "Although FIG. 1 illustrates a single set top box (STB 102 ), it should be understood that in practice, multiple set top boxes can be made to share access to the communications link 104 by cable splitting (i.e., physically and electrically interconnecting them in parallel) or by using other access architectures, which may or may not utilize switching nodes.", "[0023] In a specific non-limiting example, communication between the CSS 106 and the STB 102 may take place in accordance with EUTELSAT DiSEqC 2.0 Bus Specification v. 4.2, which describes a two way communication protocol between a satellite STB and an outdoor unit (ODU).", "The DiSEqC 2.0 Bus Specification v. 4.2 is mentioned because it allows extensions that would implement additional functionality required by a specific application.", "However, it should be appreciated that other versions of the DiSEqC specification, as well as other protocols, including proprietary ones, can be used without departing from the scope of the present invention.", "[0024] The communications link 104 supports communication over a frequency range that may be L-band (950 MHz to 2150 MHz), without being limited thereto.", "This frequency range is divided into “user bands.”", "One of these user bands is assigned to the STB 102 (or in the case of a multi-tuner set top box, several user bands may be assigned to the STB 102 but each such user band is uniquely assigned to each tuner).", "A reverse channel may also exist to permit upstream communication (i.e., from the STB 102 to the CSS 106 ).", "In various embodiments, the reverse channel may be a separate frequency channel, a tone that is modulated, etc.", "A separate cable may also be used for the reverse channel.", "[0025] The STB 102 includes a memory 103 (e.g., flash memory or any other type of non-volatile storage media) that indicates its assigned user band, thus allowing the STB 102 to utilize the correct central frequency when receiving signals from the CSS 106 along the communications link 104 .", "The memory 103 also stores an identifier of the STB 102 such as an IRD or a serial number (where a multi-tuner STB is concerned, an extension may be provided for uniquely identifying each tuner).", "Other ways of identifying the STB 102 are of course possible, including various forms of codes and addresses.", "Other data may also be stored in the memory 103 as will become apparent from the description to follow.", "[0026] The CSS 106 includes or has access to a memory 107 (e.g., flash memory or any other type of non-volatile storage media) in which it stores the assignment of user bands to set top boxes including the STB 102 .", "For example, the STB 102 may be identified by its IRD, serial number or other identifier mentioned above, while the assigned user band may be identified by its center frequency or by an index or other code.", "The memory 107 also stores an identifier of the CSS 106 , such as a serial number, hardware identifier (HWI), or other form of identifier.", "Other data may also be stored in the memory 107 as will become apparent from the description to follow.", "The memory 107 may be part of the CSS 106 or accessible thereto via a data network such as the Internet.", "[0027] The STB 102 is connected to a display set viewed by a viewer.", "The display set could be a television set, computer monitor, wireless communication device or a device implementing a combination of the aforementioned functionalities.", "The STB 102 performs video decoding and other functions, including receiving an indication of the channel that the viewer wants to watch.", "In particular, over time, the STB 102 generates tuning requests based on channels identified by the viewer.", "Specifically, a channel identified by the viewer (e.g., via a remote control device or by pressing a button on the display set) is mapped to a desired satellite transponder channel by the STB 102 .", "The desired satellite transponder channel is identified in a tuning request sent to the CSS 106 over the communications link 104 in accordance with a format, which can be the DiSEgC™ format (without being limited thereto).", "The tuning request can be sent over the reverse channel (e.g., using a separate frequency band reserved for upstream communication, one or more DiSEgC™ tone frequencies, a separate cable, etc.) from the STB 102 to the CSS 106 .", "[0028] The CSS 106 is responsible for receiving tuning requests from the STB 102 (and other set top boxes, if applicable) and processing the requests.", "Specifically, the CSS 106 determines where in the satellite frequency range the desired satellite transponder channel is located.", "A mapping (e.g., in the memory 107 ) could be consulted to this effect in order to identify a target wideband satellite frequency range.", "Then, the CSS 106 provides a satellite feed unit 108 (e.g., a low noise block downconverter 110 connected to a satellite dish 112 ) with a control signal.", "With additional reference to FIG. 2 , the control signal allows the satellite feed unit 108 to admit a wideband satellite signal 202 to the CSS 106 , such signal occupying the target wideband satellite frequency range.", "Examples of parameters that can be controlled by the CSS 106 include the polarization and frequency range of the admitted wideband satellite signal 202 .", "Further information regarding an example manner of controlling a low noise block downconverter can be found in the document entitled “Low Noise Block Downconverter”", "from Satellite Signals Limited, available at www.", "satsig.net/Inb/explanation-description-Inb.", "htm.", "This document is hereby incorporated by reference herein.", "[0029] Next, the CSS 106 isolates the desired satellite transponder channel 204 within the wideband satellite signal 202 .", "This can be done by translating in the frequency domain the desired satellite transponder channel 204 to the user band (i.e., the tuner central frequency) assigned to the STB 102 that originated the tuning request.", "A surface acoustic wave (SAW) filter can be used for this purpose.", "The resulting signal, denoted 206 , is sent to the STB 102 .", "The signal 206 can be “stacked”", "(i.e., frequency multiplexed) with other signals in other user bands destined for other set top boxes.", "These are all sent together and each individual STB will know which signal to consider, based on its own user band, which is uniquely assigned.", "[0030] Thus, it will be appreciated that the tuner in the STB 102 does not need to change its central frequency during normal operation.", "Rather, it is the CSS 106 that takes over the tuning function, mapping a desired satellite transponder channel to the tuner's central frequency.", "[0031] In accordance with a specific non-limiting embodiment of the present invention, a securitization protocol is provided for securing communication between the CSS 106 and the STB 102 .", "[0032] With reference to FIG. 3 , at step 302 , the STB 102 receives a trigger 350 .", "In one embodiment, the trigger 350 can be sent when the head end 102 wishes to secure communications between the CSS 106 and the STB 102 .", "In this case, the STB 102 receives the trigger 350 via the satellite dish 112 , the low noise block downconverter 110 , the CSS 106 and the communications link 104 .", "In another embodiment, the trigger 350 can be sent under control of the CSS 106 .", "The trigger 350 can be issued by the appropriate entity a single time, periodically, after every cold boot, or generally at any arbitrary time instant or instants.", "In another embodiment, which may be less secure, the trigger 350 can be generated by the STB 102 itself, either autonomously or based on input received from the viewer.", "[0033] At step 304 , in response to having received the trigger 350 at step 302 , the STB 102 obtains a security data element 360 .", "The security data element 360 may take on various forms and may be obtained in various ways, several of which are described later on in greater detail.", "[0034] At step 306 , the STB 102 combines the security data element 360 with data destined for the CSS 106 (such as a tuning request) to formulate a message 370 .", "Combining can include appending the security data element 360 to the data, encrypting the data with the security data element 360 , etc.", ", as will be described herein below in greater detail.", "Message 370 is sent to the CSS 106 over the reverse channel (e.g., using a separate frequency band reserved for upstream communication, one or more DiSEgC™ tone frequencies, a separate cable, etc.).", "[0035] From the perspective of the CSS 106 , it cannot know a priori whether or not any given received message from any given set top box (such as message 370 from the STB 102 ) is indeed legitimate.", "Therefore, at step 308 , upon receipt of message 370 from the STB 102 , the CSS 106 verifies its legitimacy in one of several possible ways, each of which involves consulting the memory 107 , and some of which are described below in greater detail.", "A received message that will have been formulated based on combining data destined for the CSS 106 with the security data element 360 will be considered “legitimate”", "by the CSS 106 , as will be described later on.", "[0036] At step 310 , the CSS 106 takes an action depending on whether or not the received message (in this case message 370 ) was determined to be legitimate at step 308 .", "[0037] For example, if the received message (in this case message 370 ) was found to be legitimate at step 308 and included a tuning request (which may specify a desired satellite transponder channel), the action taken at step 310 can comprise serving the tuning request on behalf of the STB 102 .", "This can include controlling the low noise block downconverter 110 so as to admit a wideband satellite signal from an ambient signal received at the satellite dish 112 , isolating the desired satellite transponder channel from the wideband satellite signal and frequency translating the desired satellite transponder channel into the user band assigned to the STB 102 .", "[0038] On the other hand, if the received message (in this case message 370 ) was found not to be legitimate at step 308 , then the action taken at step 310 can comprise returning an error message to the STB 102 in its assigned user band, in response to which the STB 102 can display (or otherwise convey) an error message perceptible by the viewer.", "[0039] As mentioned above, the security data element 360 may take on various forms in different embodiments, with corresponding differences in the manner in which it is combined with data to formulate messages (such as message 370 ) sent to the CSS 106 and also differences in the manner in which the CSS 106 verifies a received message's legitimacy.", "The following non-limiting example scenarios offer different levels of security with different levels of implementational complexity.", "It should also be appreciated that other security scenarios are possible.", "[0040] In a first example security scenario, the security data element 360 is a key obtained from the CSS 106 .", "The key may take the form of an identifier of the CSS 106 or other data known to the CSS 106 .", "Specifically, with reference to FIG. 4 , the STB 102 issues a key request message 402 to the CSS 106 .", "The CSS 106 accesses the memory 107 and extracts an identifier 404 of the CSS 106 (e.g., the HWI).", "The CSS 106 then issues a response message 406 to the STB 102 containing the identifier 404 .", "At the STB 102 , the identifier 404 received from the CSS 106 is stored in the memory 103 as the security data element 360 .", "[0041] Thus, combining the security data element 360 with data (e.g., a tuning request) destined for the CSS 106 in order to formulate message 370 (as mentioned at step 306 ) comprises the STB 102 encrypting such data with the identifier 404 using any desired technique for symmetric encryption, i.e., in such a way that the same identifier 404 can be used by the CSS 106 to successfully decrypt messages that have been encrypted.", "[0042] Accordingly, at step 308 , the “processing”", "carried out by the CSS 106 on message 370 is an attempt to decrypt message 370 using the identifier 404 that had previously been sent to the STB 102 which, if successful, will yield the data destined for the CSS 106 (e.g., a tuning request).", "[0043] In a second example security scenario, the security data element 360 is also a key obtained from the CSS 106 , except that the key is an encryption key used in asymmetric encryption.", "The encryption key may take the form of a public key forming part of a public-private key pair, with the corresponding private key being held secret in the memory 107 of the CSS 106 .", "With reference to FIG. 5 , the STB 102 issues a key request message 502 to the CSS 106 .", "The CSS 106 accesses the memory 107 and extracts a CSS public key 504 .", "The memory 107 also stores a complementary CSS private key 505 in association with the CSS public key 504 as part of a CSS key pair 507 .", "The CSS 106 then issues a response message 506 to the STB 102 containing the CSS public key 504 .", "At the STB 102 , the CSS public key 504 received from the CSS 106 is stored in the memory 103 as the security data element 360 .", "[0044] Thus, combining the security data element 360 with data destined for the CSS 106 (e.g., a tuning request) in order to formulate message 370 (as mentioned at step 306 ) comprises the STB 102 encrypting such data with the CSS public key 504 using any desired technique for asymmetric encryption, i.e., in such a way that successful decryption requires a complementary decryption key, in this case the CSS private key 505 .", "[0045] Accordingly, at step 308 , the processing carried out by the CSS 106 on message 370 is an attempt to decrypt message 370 using the CSS private key 505 stored in the memory 107 which, if successful, will yield the data destined for the CSS 106 (e.g., a tuning request).", "[0046] It will be appreciated that in the second example security scenario above, the CSS 106 always retains information that the STB 102 cannot access (in this case, the CSS private key 505 ), which enhances security relative to the first security scenario.", "However, there is more processing overhead required of the processors at the CSS 106 and the STB 102 .", "[0047] Several techniques can be applied to the second example security scenario in order to further enhance security.", "One security enhancement is to change the key pair over time.", "That is to say, a different CSS public key can be provided to the STB 102 at various times, e.g., periodically or for every N th message, where N can be as low as 1.", "To this end, the memory 107 at the CSS 106 may include a table containing a plurality of key pairs from which a new pair is selected when needed.", "It is also possible for the pairs to be indexed and for the CSS public keys in the table also to be indexed and previously stored in the memory 103 at the STB 102 .", "Thus, when a new key pair is selected (either by the CSS 106 or by the STB 102 ), a new index is selected without revealing the CSS public key.", "[0048] Another security enhancement is to encrypt the reverse channel.", "Specifically, the memory 103 at the STB 102 may store a STB public key and a complementary STB private key.", "The key request message 502 sent by the STB 102 can include the CSS public key, which is then used by the CSS 106 to encrypt the response message 506 containing the CSS public key 504 .", "The received (encrypted) response message 506 is then decrypted by the STB 102 using the STB private key to reveal the CSS public key 504 contained therein.", "In this way, only a set top box with access to the STB private key would be able to properly obtain the CSS public key 504 , which enhances security.", "[0049] A third example security scenario is a variant that requires very little in the way of computational overhead.", "Specifically, with reference to FIG. 6 , the memory 107 at the CSS 106 stores a list 602 of identifiers of set top boxes that are considered “authorized.”", "In an alternative embodiment, the list 602 contains identifiers of set top boxes that are considered “not authorized.”", "The list 602 of authorized set top boxes (or unauthorized set top boxes) can be updated over time by the head end 120 .", "[0050] Additionally, an identifier of the STB 102 , denoted 604 , is stored in the memory 103 at the STB 102 .", "In accordance with the third security scenario, the security data element 360 comprises the identifier 604 , and data sent to the CSS 106 (e.g., a tuning request) can be combined with the identifier 604 simply by appending the identifier 604 to such data.", "Thus, message 370 contains both the data destined for the CSS 106 and the identifier 604 .", "[0051] Accordingly, at step 308 , the processing carried out by the CSS 106 on message 370 containing the data destined for the CSS 106 includes extraction of the identifier 604 and comparison of the identifier 604 to the identifiers in the list 602 .", "If the identifier 604 appears on the list 602 and the list 602 contains identifiers of set top boxes that are considered authorized, then message 370 is considered legitimate, otherwise the message is considered not legitimate.", "On the other hand, if the identifier 604 appears on the list 602 and the list 602 contains identifiers of set top boxes that are considered not authorized, then message 370 would be considered not legitimate, otherwise the message would be considered legitimate.", "[0052] It should be appreciated that in the third example security scenario, the STB 102 does not require knowledge of information about the CSS 106 .", "In contrast, the CSS 106 needs to know which set top boxes are authorized (or not authorized).", "[0053] In view of the foregoing, it should be appreciated that if a new set top box is connected to the CSS 106 once the above securitization protocol has been executed, functionality of such new set top box will be impaired, because it does not have access to an appropriate security data element (e.g., the identifier 404 of the CSS 106 , the CSS public key 504 , the identifier of an authorized STB) that would allow it to formulate a legitimate message for the CSS 106 .", "In particular, this prevents pirated set top boxes from successfully communicating with the CSS 106 in order to carry out certain importnat functions such as channel changes.", "[0054] It will also be appreciated that even if the STB 102 is capable of formulating messages that are considered by the CSS 106 to be legitimate, it may still be necessary to overcome conventional security barriers that may exist before viewing of a television channel is allowed.", "Such additional security barriers may include the provision of conventional conditional access codes, smart cards and the like.", "[0055] Thus, it will be appreciated that embodiments of the present invention assist in combating piracy and improving signal integrity.", "As a result, revenue loss due to signal theft is reduced and confidence (by the content owners) in the satellite signal integrity is increased, with a potential positive impact on revenues.", "[0056] Those skilled in the art will appreciate that in some embodiments, the STB 102 and/or the CSS 106 may be implemented using one or more computing apparatuses that have access to a code memory which stores computer-readable program code (instructions) for operation of the one or more computing apparatuses.", "The computer-readable program code could be stored on a medium which is fixed, tangible and readable directly by the one or more computing apparatuses, (e.g., removable diskette, CD-ROM, ROM, fixed disk, USB drive), or the computer-readable program code could be stored remotely but transmittable to the one or more computing apparatuses via a modem or other interface device (e.g., a communications adapter) connected to a network (including, without limitation, the Internet) over a transmission medium, which may be either a non-wireless medium (e.g., optical or analog communications lines) or a wireless medium (e.g., microwave, infrared or other transmission schemes) or a combination thereof.", "In other embodiments, the STB 102 and/or the CSS 106 may be implemented using pre-programmed hardware or firmware elements (e.g., application specific integrated circuits (ASICs), electrically erasable programmable read-only memories (EEPROMs), flash memory, etc.), or other related components.", "[0057] Certain adaptations and modifications of the described embodiments can be made.", "Therefore, the above discussed embodiments are to be considered illustrative and not restrictive.", "Also it should be appreciated that additional elements that may be needed for operation of certain embodiments of the present invention have not been described or illustrated as they are assumed to be within the purview of the person of ordinary skill in the art.", "Moreover, certain embodiments of the present invention may be free of, may lack and/or may function without any element that is not specifically disclosed herein." ]
FIELD OF THE INVENTION This invention concerns an apparatus for timing races including an optical arrangement installed at a fixed station and in the extension of a crossing line of a race comprising several competitors, in order to project an image of such line onto a photo sensitive bar which includes a plurality of pixels juxtaposed in a single column. BACKGROUND OF THE INVENTION The patent document CH-A 590 518 has already described a system for the determination of times separating the passages of moving objects to the right of a reference line substantially perpendicular to the trajectory. This system consists of employing a television camera equipped with a cathode ray tube, which camera is directed onto the reference line, recording the signals provided by said camera and simultaneously signals provided by a timekeeper and reproducing the signals with the aid of a monitor. In order to accomplish this, one employs a camera by means of which one effects a unidirectional linear scan coinciding with the reference line and a reader effecting a linear bidirectional scan in a manner such that the successive scans of the reference line by the camera are spread out over the screen of the reader in a direction perpendicular to that in which the unidirectional scans are effected, thus in the direction of the trajectory of the moving objects. The document mentions that this camera may be of a conventional type, where however the two scans are permuted in a manner such that the more rapid scan is effected in a vertical direction and a slower scan has been suppressed. As a variant it is said that one will employ preferably a diode camera of the type referred to as solid state in the place of a cathode ray tube in order to avoid marking the tube or indeed the rapid deterioration of the latter. This system is illustrated on FIGS. 1 and 2 of the present description. The moving object 2 is displaced at a speed V m in front of lens 1 of the camera. Behind the lens is found a unidimensional photosensitive arrangement 5 using a solid state detector, here further called a CCD bar. The image of the moving object runs past at the speed Vi in front of arrangement 5. FIG. 2 shows how this arrangement is formed which includes a row of elementary pixels 6 arranged side by side. The incident light coming from the reference line to be captured produces charges on each of the detectors, which charges represent the intensity profile of a line of the image at a given instant. These charges are periodically transferred in the sense of arrows 9 into a shift register 7 bearing as many elements 8 as there are pixels 6. A clock signal 12 at TV frequency empties the contents of the line towards amplifier 10 in the form of a video signal 11. These video signals are next memorized, then visualized in a manner to represent, in the form of an image, the development in time of the line under observation (finish line for instance). Several unidirectional arrangements are presently available on the market. They are all equipped with a substantial number of pixels ( >1000) to assure high resolution. For further details on this subject, reference may be had to the technical publications of the manufacturers, for instance to the publication concerning the arrangement GH 7801 A of Thomson-CSF. Complete cameras may even be obtained from the Fairchild Company under the reference CCD 1100C to 1500C or again from the i2S Company (Bordeaux, France) under the denomination iDC 133. In the system which has just been described, it has been seen that the incident light produces charges on the row of detectors 6 which charges are periodically transferred towards the output 10 via a shift register 7. Here the transfer frequency is fixed since it is tied to an ordinary television standard. In effect, in the cited document is noted a frequency of the images which is 25 units per second, each half image lasting 20 milliseconds. From this fact the system described has the merit of employing standard material as far as concerns the camera as well as the monitor and the recorder. It is thus inexpensive. The system described unfortunately presents at least two major disadvantages which determine that it has never been employed in practice and remains at the stage of a prototype. The first difficulty concerns the time of exposure of the pixels which is very small. Effectively, according to the European standard, a half image is explored in 20 ms (50 Hz) and each half image includes 312.5 lines. It follows that the duration of a line is equal to 20/312.5 0.064 ms=64 μs and that the scan frequency is 1/64 μs, i.e. 15,625 lines per second. Thus, in employing a unidimensional photosensitive arrangement with standard TV sweep, each pixel will be excited only during 64 μs per scan. This represents an extremely short time which limits the domain of application of the arrangement to scenes presenting substantial lighting, since for average illumination the signal gathered will not emerge at all or very little from the background noise, at least with the means presently available. The second difficulty concerns the deformation of the images collected. It will be understood in effect that to obtain a non-deformed image, it will be necessary that the speed of refreshing of the photo sensitive arrangement given by the clock signal 12 (see FIGS. 1 and 2) correspond to the speed Vi of the image running past on said arrangement. The image collected will be compressed if the speed Vi is greater than the refreshing speed or on the contrary, will be dilated if the speed Vi is less than said refreshing speed. An example drawn from practical situations will facilitate understanding of the problem which is posed. The CCD bar as mentioned hereinabove includes a multiplicity of pixels of a substantially squared off surface, the side of which measures substantially 13 μm. With the standard TV at 625 lines, these 13 μm are scanned as already been said in 64 μs, which corresponds to the image of a moving object which would be displaced at the speed Vi of: ##EQU1## In this case, the scan frequency is adapted to the speed of the race and the images reproduced appear without deformation. Now this value corresponds to the speed Vi of an automobile race running in front of the CCD bar. Should one now wish, with the same apparatus, to capture the images of an athletics race of which the speed of the image Vi may be estimated to be 26 mm/s, the image collected will be strongly dilated in width deforming the shapes of the athletes to the point of rendering them unrecognizable. If one wanted thus to obtain an image without deformation of the athletics race, it would be necessary to lower the scan frequency of the bar which correspondingly will increase the time during which the pixels of the bar are exposed. In taking the speed of 26 mm/s and a pixel of 13 μm on one side, one may calculate the exposure time, then the scan frequency to be applied to the bar. The exposure time is: ##EQU2## and the scan frequency is 1/500 μs=2,000 lines per second. To take another example, the exposure time and the scan frequency would be respectively of 3.25 ms and 307 lines per second if one considered a boating trial where the speed of the image Vi running in front of the bar is on the order of 4 mm/s. It follows from what has just been said that in order to obtain a non-deformed image of the course to be timed, it is indispensable to adapt the scan frequency of the bar to the speed of the image running past onto such bar in the same manner as one adapts the speed of film in a system employing a film running past behind a slot (process of photo-finish described in the patent document CH-A-399 028). In the arrangement set forth in patent document CH-A 590 581 cited hereinabove, this adaptation is effected only for high speed races such as for automotive vehicles. It will be understood that in order to capture the image of an athletics race, not only must the scan frequency of the bar be reduced to the values indicated hereinabove, but further it is necessary to have available a reader (monitor, video recorder) the scan frequency of which is tuned and synchronous with that which explores the bar. This will never be the case if one wishes to employ a commercial reader conceived for a single frequency (15,625 lines per second) and established once and for all. In order to resolve this problem, it has been proposed to employ a reader having an adaptable frequency. One could also propose that the processing and storing of images be effected in a PC. Whatever be the chosen solution, it will be necessary to employ a complex and onerous collection of apparatus. The patent document EP-A-O 223 119 proposes however an apparatus for capturing the image of sporting races including a pulse generator for controlling the transfer of charges from one sensor to the other, in a manner such that the speed of this transfer is made to correspond to the speed of the image of the race which is passing in front of the arrangement. No detail however is given concerning the manner in which the image is reconstructed the text being satisfied to explain that this reconstitution is brought about according to techniques known in television, the line frequency being synchronized with the charge transfer frequency, which implies a monitor and a video recorder which are non-standard. The patent document EP-A-0 207 675 likewise proposes a video recording apparatus for sporting races including a one dimensional sensor in the form of a bar. The signal gathered at the output of the sensor is converted by an A/D converter into a series of image elements which are stored in a video memory in order to form a plurality of images arranged end to end. This system is however limited to the capacity of the memory, typically to 16 TV images as the description indicates. Such is due to the fact that in this system there are not two buffer memories alternately working, one in reading and the other in writing as is the case in the invention which will be described hereinafter. The patent document US-A-4 133 009 proposes for its part two buffer memories working alternately. However, the capacity of these memories is determined by an entire TV image from whence there does not result difficulty in reconstituting the TV image in a standard monitor and video recorder. This system cannot be applied to capturing the image of races along with a time scale for one arrives at ambiguities in passing from one image to the other (overlapping) since at no moment is there to be found on the screen the juxtaposition of a plurality of image portions at the same time, so as to bring about a temporal continuity between one of the portions and the portions which precede and follow said portion, as is proposed by the present invention. If this invention employs several of the characteristics as described in the three documents which have just been discussed, it is with an entirely different purpose from that pursued by said documents. The problem to be solved here results from the fact that as the frequency of image acquisition by the bar is not synchronized with the frequency of visualization, one proceeds with generating portions of an image employing buffer memories, such image portions being next stored in an image memory, then read in a discontinuous fashion by jumping over portions of the image in synchronism with a standard TV sweep. Thanks to this arrangement, the images are recorded and visualized by means of a standard commercial recorder and monitor at a scan frequency which is fixed and standardized. SUMMARY OF THE INVENTION Thus, the principal purpose of this invention is to offer an apparatus for timing races equipped with a one-dimensional CCD bar which is adapted to several speeds of races without deforming the image and while employing a simple image sensor, operating to the ordinary television standard which is currently obtainable on the market. Thus with this system the monitor and the video recorder are inexpensive and contribute accordingly to reduce the price of the overall apparatus assembly. To obtain this result, the apparatus of the invention is notable in that it includes: means for reading the contents of the bar at a predetermined frequency chosen as a function of the speed of the race, said contents showing up in the form of an electrical signal corresponding to the intensity profile of the line image at a given instant; first and second buffer memories alternately adapted to memorize a predetermined number of electrical signals resulting from successive readings of the bar in order to form respectively first and second image parts of the race; means for alternately transferring said first and second image parts into an image memory adapted to store n image parts of substantially equal capacity, the apparatus being arranged in a manner such that, when the first buffer memory stores the signals issuing from the bar, the image part contained in the second buffer memory is written into the image memory and vice-versa, said image memory exhibiting at the time of each writing an image part in the course of writing and n-1 image parts already written; means for reading in accordance with a predetermined order said n-1 parts already written into the image memory in a manner such that the first image part read corresponds to the part freshest in time already written into the image memory and so on in accordance with a chronological order; a monitor of standard TV type for displaying on a screen the n-1 image parts read in the image memory in a manner such that, at the time of each writing of a new image part into the image memory, the freshest portion appearing on the screen takes the place of the preceding portion, this latter undergoing a jump displacement so as to be placed beside said freshest portion, and a recorder of standard TV type for recording the images appearing on the monitor. The invention will now be set forth with the aid of the following description illustrated by way of example by the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 represent the prior art as discussed hereinabove; FIG. 3 is a block diagram illustrating the invention according to a simplified embodiment permitting solely the acquisition of images and including essentially two buffer memories and an image memory; FIG. 4 is a graphical illustration of how from portions of the image stored in an image memory one constructs a complete image visible on a monitor; FIG. 5 is a block schematic showing the invention according to a more developed embodiment permitting, in addition to the acquisition of images, the inscription of the time corresponding to the images; FIG. 6 is a graph showing partially the graph of FIG. 4 to which a time scale has been added; FIG. 7 is a timing diagram applicable to the block schematic of FIG. 5 showing the progress of image acquisition and FIG. 8 shows how the buffer memories and the image memory are organized as well as the manner in which the signals of said buffer memories are transferred to said image memory. DESCRIPTION OF THE PREFERRED EMBODIMENT The block schematic of FIG. 3 shows a simplified embodiment of the invention. Here runners 2 each progressing in a corridor 4 at a speed Vm cross in turn a passage line 90 which may be the finish line of the race. In the prolongation of this passage line is located an optical arrangement or lens 1 forming part of a camera 15. The image of the line 90 is formed on a photo sensitive bar 5 which is located behind the lens 1. In a plane perpendicular to FIG. 3, bar 5 is as illustrated on FIG. 2 and is comprised of a plurality of pixels juxtaposed in a single column. The image of the runner runs past at speed Vi in front of the bar. A time base or timer 25 coupled to the camera by connection 35 enables reading the contents of the bar at a predetermined frequency, each reading being followed by a refreshing of the bar. The reading frequency is chosen to correspond to the speed Vi of the image of the race. It is understood thus that at any given instant the contents of the bar existing in the form of an electrical signal is found to be equal to the intensity profile of the image of line 90. The reading frequency of the bar is chosen by the operator of the apparatus as a function of the speed of the race for which he must retain the images. For this the operator has available a keyboard 27 on which he may introduce manually the value of such speed. A microcontroller 26 serves as an interface between keyboard 27 and the time base 25, which permits to derive from the time base --generally furnishing the time of day--the reading frequency chosen by the operator. Likewise from the keyboard the operator may signal the person responsible for giving the starting signal of the race that the apparatus is ready to receive images of the race. This signal issues from the time base 25 via the line R (ready). Inversely, the time base 25 of the apparatus may be reset to zero, then started by the starting signal of the race and this by the line S (start). It should be mentioned that the time base 25 and the microcontroller are circuits obtainable in commerce, for instance under the designation Intel 80186 which combines blocks 25 and 26 in a single integrated component. The electrical signals resulting from the successive readings of the bar 5 are memorized initially in a first buffer memory 19 via a switch 28 set according to the position shown on FIG. 3. In the embodiment taken as example, when 128 columns including 512 pixels have been memorized in buffer 19, timer 25 switches the output of the bar onto the input of a second buffer memory 20 which memorizes in turn 128 new columns captured by the bar. One is thus in the presence of image portions each including 128 columns. In the example of a sweep of 2,000 columns per second, each portion of the image thus represents a race time of 128/2,000=64 ms. FIG. 3 shows that the contents of buffer memories 19 and 20 may be alternately led via another switch 29 to an image memory or video RAM 21. This switch is controlled by timer 25. It is seen that when the buffer memory 19 stores the electrical signals coming from bar 5, the content of buffer memory 20 is transferred into the image memory 21 and vice-versa. For this it is understood that switches 28 and 29 are operated in synchronism and controlled by timer 25. It will here be noted that the buffer memories are capable of storing 128 columns, each comprising 512 distinct signals. These may be memories of the type Hitachi HM 62536. The image memory 21 has a capacity sufficient to memorize n portions of the image coming from the buffer memories 19 and 20. When the apparatus operates and at each instant of its operation, it will be understood that the memory image presents one portion of image in the course of being transferred or writing in and n-1 portions of image already transferred or already written. Such a memory may be of the type Intel 514256. By means of a video controller 24--which may be of the type Intel 82786--one next reads according to a predetermined order the n-1 portions of the image already written into the video RAM 21 in a manner such that the first portion of the image read corresponds to the freshest temporal portion written into said video RAM and so on according to chronological order. Next the images read according to the order indicated hereinabove are displayed on a monitor 23 of ordinary TV standard and parallelly registered in a recorder 22 of ordinary TV standard in a manner such that after each writing of a new image portion into the image memory 21 the freshest portion displayed on the screen of the monitor 23 takes the place of the portion previously displayed, this latter undergoing a displacement by jump in order to be placed beside the freshest portion. Should one wish for a time increase extending from left to right on the screen, it will be arranged so that the freshest portion of the image appearing on the screen is found to the right of such screen, the display of a new portion of the image displacing the portion of the image which was previously found there toward the left. There it concerns an image reconstruction from several partial images, each of said partial images including in the embodiment taken as an example 128 columns. How the operation of the synchronization with an ordinary TV standard is brought about will be explained hereinafter when a more complete embodiment of the invention is discussed. FIG. 4 will facilitate understanding of the reconstruction mechanism of the image as mentioned hereinabove. Reference 21 designates the image memory and reference 23 the monitor screen. The image memory may contain five portions of the image represented by five compartments numbered 1 to 5. There is initially the transfer of the contents of the buffer memory 20 (see FIG. 3) into the image memory 21. The runner 70 is then written into compartment 1. Following this transfer, one reads compartments 2 to 5 of the image memory and one displays them on the monitor. In the example, compartments 2 to 5 of the memory being empty of information, the monitor will not display any information (FIG. 4a). When the buffer memory 19 is entirely filled by the image portion acquired from bar 5, switches 28 and 29 change position and the content of buffer 1 is transferred into compartment 2 of the image memory: the runner 71 is written into compartment 2. Following this writing in one reads in order 3, 4, 5 and 1, the compartments of the image memory. The runner 70 appears to the right of the monitor screen 23 (FIG. 4B). During the following stage shown on FIG. 4C, there is a new acquisition in the compartment 3 of the image memory, which acquisition is determined by runner 72. Following this acquisition, one reads again the compartments already written from the image memory in a manner such that the first image portion read corresponds to the portion which in time is the freshest already written into the memory. Here it concerns runner 71 followed by runner 70 and the two empty compartments 5 and 4. There then appears on the monitor screen from right to left the runners 71 and 70, the runner 70 being displaced towards the left in order to leave its place to the new arrival 71. During the following stage (FIG. 4D), it is runner 71 which is transferred into the image memory 21 bringing about the display on the monitor screen 23 of runners 72, 71 and 70. The process continues thus as shown on FIGS. 4E and 4F. It is to be noted on FIG. 4F that the transfer of the new runner 74 into the image memory has chased from the screen the first runner 70 which no longer appears thereon. In the example shown here, one sees that the image memory may contain five image portions (n=5) and that the monitor screen displays four of these portions (n-1=4). It will be noted that the invention is not limited to this arrangement and that n may be different from 5. What precedes has explained the general principle of the invention, to wit how one constructs a complete image from image portions which are displaced by jumps as their acquisition progresses. Here it concerns however a much simplified version of the invention which does not enable appreciation of the rank of the runners. As in most cases, in addition to the necessity of separating the runners according to the rank which they occupy, it is indispensable to determine the time taken by each competitor in order to traverse the space separating the starting line from the line under control; it is necessary to attach to the race image a time scale corresponding to these images. FIG. 5 shows a perfected embodiment of the invention which takes up all the elements discussed in respect of FIG. 3 in adding to them elements enabling the creation of a time scale and other elements bringing certain advantages which will appear upon reading the lines to follow. Camera 15 summarily schematized on FIG. 5 includes a bar 5 of at least 512 pixels arranged in a column. The signals coming from the bar are amplified by an amplifier 16 of which the gain may be varied, for example as an automatic function of the lighting of the objective to be sensed. A first converter 17 transforms the analog signals coming from amplifier 16 into digital signals, each pixel being represented by 8 bits (=1 byte). The first six bits encompass information relative to 64 grey levels of pixel, the last two being employed for instance for transmitting information relative to the colour of the pixel. The camera is controlled by a controller 18 from whence are issued for instance the scan frequency of the bar (line 49), the gain control of the amplifier (line 50) and the converter control (line 51). Controller 18 receives signals from the time base 25 (line 35) and is coupled to the microcontroller 26 by a bidirectional line 61. It has been mentioned hereinabove that this camera may be bought already complete from the company i2S (Bordeaux, France). The signals coming from camera 15 by line 91 are led to switch 28 in order to alternately feed the buffer memories 19 and 20 as has already been explained hereinabove. In the same manner, from the moment that a buffer is filled, its contents are written into the image memory 21 via switch 29 and line 55. The signals gathered at the output of the image memory are led via line 54 to a second converter 43 which converts the digital signal coming from the image memory into an analog signal which, via lines R, G, B is led to an encoder intended to link the system to readers (monitor and video recorder) of a standard type according to the ordinary standard colour TV. It will be mentioned that one may employ for the second converter 43 the Booktree BT 478 circuit and for the coder the Motorola MC 1377 circuit following the PAL or NTSC standard. A Philips circuit TDA 2506 would enable adaptation to the SECAM standard. The other elements (buffers, image memory, timer, microcontroller) are of the same type as those already mentioned hereinabove. The schematic of FIG. 5 is to be noted in the sense that it enables creation of a graphic time scale with digital references enabling easy reading of the race time. The graphic generator is represented at 39. It forms, together with the video controller 24 already mentioned in connection with FIG. 3 and a video address generator 40, a unique component 60 which is of the type Intel 82786 already identified. The construction of the image is brought about in the same manner as that discussed with reference to FIGS. 3 and 4 with a time scale in addition. FIG. 6 shows a special situation taken at the same moment as that represented on FIG. 4c. The image memory 21 includes a zone image 81 comprising runners 70, 71 and 72. This zone includes five portions, each composed of 128 columns, each column itself comprising 480 bytes. The image memory 21 includes further a time scale zone 82 comprising time subdivisions 92 and a writing arrangement 93 labelled in minutes, seconds and tenths of a second (for example 1'13"20). This zone likewise includes five portions, each composed of 128 columns, each column including 32 bytes. In FIG. 6, the runner 72 is in the course of being written into the image memory and the runners 71 and 70 have already been written into said memory. It follows that there appear on screen 23 runners 71 and 70, the runner 71, the most recently acquired, appearing at the right of the screen. If one traces straight lines 105 and 94, which moreover are applied to form a cursor which will be discussed subsequently to the vertical of the position of the runners, one will find that the runner 70 has crossed the space separating the starting line from the line under control in a time equal to 1'13"15, while runner 71 has traversed the same space in a time equal to 1'13"213, the runner 70 preceding thus by 6.3 hundredths of a second runner 71. FIG. 7 is a timing diagram which will facilitate understanding of the arrangement of the schematic of FIG. 5. Line A of FIG. 7 indicates the time scale, 20 milliseconds separating two divisions. Line B indicates in the ordinary standard TV 625 lines and, referenced by 1, 2, 3 etc., the succession of half images each being of 20 ms. The readers (monitor 23 and recorder 22) respond to this standard in the example chosen here. From the camera 15 one acquires the images at a rate that one chooses at 2,000 columns per second, which corresponds to the athletics race mentioned hereinabove. The time for filling a buffer memory 19 or 20 will thus last 128/2,000=64 ms, which is shown on lines C and D of the diagram of FIG. 7. When buffer 1 is in acquisition, switches 28 and 29 occupy the position drawn on FIG. 5 and buffer 2 is in the situation of being able to transfer its contents to the image memory. When buffer 1 is filled, the timer 25, via an address generator the role of which will be explained further on, causes switches 28 and 29 to reverse roles via line 30. Buffer 1 may then be transferred into the image memory (arrow 95). This transfer is shown by line E of the graph of FIG. 7. The figure shows that the transfer does not take place immediately, but only in synchronization with the beginning of the scan of the half image following immediately the end of the filling of buffer 1, as it happens the beginning of the half-image 5 of the line B. At the end of this operation the 128×512 bytes of the buffer 1 are present in the image memory and the transfer time will have lasted during the time shown at 96 on line E. The portion of the image memorized in the image memory may then be visualized on the monitor screen. This visualization commences from the beginning of the scan of a half-image following immediately the end of the transfer into the image memory (arrow 97), as it happens at the beginning of the half-image 6 (line B) and stops at the end of the half-image 8 from which it is the buffer 2 transferred by 98 into the image memory which is visualized on the screen according to the same process as that explained hereinabove with reference to buffer 1. It will next be noted that the portions 1, 2, 3 etc. visualized on the screen (line G) are then completely synchronized with ordinary standard TV images. The figure shows that portions 1, 3, 4 and 5 last 60 ms and portion 2 lasts 80 ms. If one were to continue the graph, one would find new portions at 80 ms, for instance that which would be the portion 7 of line G. One thus finds the portions of the visualization of which the duration of immobilization on the screen covers three, respectively four half-images, which corresponds to at least one complete TV image in the first case and two complete images in the second case. One will add to this that this transfer of the image portion contained in the buffer towards the video RAM 21 will be effected during the TV lines which are not used, i.e. in the example and for one image during 625-512 =113 lines. This transfer must be synchronized with the image frequency or interlace frequency and one will have available to bring this about at most three half-images. The graph of FIG. 7 shows a transfer brought about once, but one will understand that it could be effected three times. Such being the case, the transfer time available is 113·64 μs·3/2=10,848 μs, if 64 μs is the duration of a line in 625 line TV. This time will permit calculating the transfer time of one byte which is of 10,848 (128·512) 0.165 μs, which time is entirely compatible with the memories presently available on the market. FIG. 7 further shows in line H the creation of the time scale. While buffer 1 is loaded in images acquired from the bar, graphic generator 39 of FIG. 5, coupled to timer 25 by line 52, generates a scale of times synchronized with the columns acquired from the bar. At the beginning of the acquisition of an image portion, the race time or time of day is read on a chronometric counter. Knowing the time of origin of a portion and the time increment for each column of such portion, the graphic generator has available sufficient information to trace the time scale for the 128 columns of one portion. To accomplish this work, generator 39 has available at least 64 ms, the duration for filling a buffer memory from which duration it is necessary to subtract the transfer time of the graphic data in the video RAM. The pixels thus generated are temporarily deposited in a graphic RAM memory of 128×32 pixels forming an integral part of the graphic generator 39. This information is next transferred to the image memory 21 by line 53 at the end of the image data coming from one of the two buffers 19 or 20. The diagram of FIG. 7 shows that the transfer 96 of an image portion is followed by transfer 99 (line I) from scale 1 into the image memory (arrow 100). As soon as this transfer has taken place, the graphic generator is again available for the creation of the following scale, as it happens, scale 2 (arrow 101). Finally, the first portion of the image to appear on the screen is complete with the image of the race in the upper zone 83 and the time corresponding to the image of the race in the lower zone 85 as shown by line J of FIG. 7. FIG. 5 further shows a switch 37 controlled by the video controller 24 over line 58. It will be understood that when the image memory 21 is in the read mode (transfer of data towards the visualization screen), switch 37 is positioned as shown on the figure, while when such memory is in the write mode, the switch couples lines 34 and 57 of the schematic. Graphic generator 39 may furnish information other than that relative to the time. It is thus that in the writing zone there could appear for each image portion an order number indicating in an increasing manner the order in which these portions are acquired, which would permit facilitating the locating thereof. The graphic zone could also bear a text identifying the race with which one is concerned. In addition to what is shown on FIG. 3, FIG. 5 further shows an address generator 38 which acts directly on buffers 19 and 20 by line 36. The buffer memory used here stores the pixels, the ones behind the others, as is seen by reference 19 on FIG. 8. Pixel 1 of column 1 is followed by 128×512 pixels to end up at pixel 65536 of column 128. It follows that this type of memory is not organized to be read according to a horizontal scan associated with the ordinary standard TV. It is the role of the address generator to proceed to transfer the pixels into the image memory according to an order compatible with such ordinary TV standard. FIG. 8 shows at 21 a portion of memory 21 organized in a suitable manner. The schematic of FIG. 5 shows a video recorder 22. It is seen that image generation proceeds in a discontinuous fashion by jumps of 128 columns. This is in fact not troublesome since the images are sent to the video recorder 22, then exploited in a deferred manner in the image by image mode. Furthermore, apart from the utilization in image by image, other functions associated with such a recorder may find a utilization of interest, in particular the digitalization of the image, the zoom image in image and the research for the good image sequence, etc. Keyboard 27 of FIG. 5 enables several important functions such as: initialization of the system, date, time of day, graphic representation mode, colours, etc.; introduction and memorization of several titles; introduction of parameters, for example acquisition speed; gain, camera diaphragm; priming the start for the chronometric counter; beginning and end of acquisition; specific orders to the VCR such as positioning of the tape, search for the proper sequence image by image, stop on an image, recording, reading, etc., this as a function of the VCR possibilities; control of the cursor on the screen. The latter is shown only in read mode; preparation of titles. The cursor just mentioned hereinabove is created by a cursor generator 41 which appears on FIG. 5. This generator is adapted to generate a vertical bar of small thickness on the image displayed by the monitor and traversing the image from top to bottom. This bar may be horizontally displaced so as to attribute a time to a chosen point of the image. This cursor generator may be obtained simply by means of a ramp generator and a voltage reference to be compared therewith. The cursor width will be chosen to be on the order of two pixels. The examples given hereinabove are based on a European standard of 625 lines. It will be understood that the invention may be applied by analogy to other standards, for instance to the American standard of 525 lines.
This race timing apparatus of the video finish type includes a photo sensitive CCD bar (5) which may be read at a predetermined frequency in correspondence with the run past speed (Vi) of the image of the race. The images are stored and visualized by means of a commercial recorder (22) and monitor (23) of a fixed standardized sweep frequency. Since the image acquisition frequency by the bar is not synchronous with the visualization frequency, one proceeds with the generation of image parts using buffer memories (19, 20), the image parts being next stored in an image memory (21) and then read in a discontinuous manner by jumping over image parts in synchronism with a standard TV sweep. The apparatus enables the offering of a system at a low overall cost price since it employs a recorder and a monitor currently obtainable on the market.
Briefly summarize the main idea's components and working principles as described in the context.
[ "FIELD OF THE INVENTION This invention concerns an apparatus for timing races including an optical arrangement installed at a fixed station and in the extension of a crossing line of a race comprising several competitors, in order to project an image of such line onto a photo sensitive bar which includes a plurality of pixels juxtaposed in a single column.", "BACKGROUND OF THE INVENTION The patent document CH-A 590 518 has already described a system for the determination of times separating the passages of moving objects to the right of a reference line substantially perpendicular to the trajectory.", "This system consists of employing a television camera equipped with a cathode ray tube, which camera is directed onto the reference line, recording the signals provided by said camera and simultaneously signals provided by a timekeeper and reproducing the signals with the aid of a monitor.", "In order to accomplish this, one employs a camera by means of which one effects a unidirectional linear scan coinciding with the reference line and a reader effecting a linear bidirectional scan in a manner such that the successive scans of the reference line by the camera are spread out over the screen of the reader in a direction perpendicular to that in which the unidirectional scans are effected, thus in the direction of the trajectory of the moving objects.", "The document mentions that this camera may be of a conventional type, where however the two scans are permuted in a manner such that the more rapid scan is effected in a vertical direction and a slower scan has been suppressed.", "As a variant it is said that one will employ preferably a diode camera of the type referred to as solid state in the place of a cathode ray tube in order to avoid marking the tube or indeed the rapid deterioration of the latter.", "This system is illustrated on FIGS. 1 and 2 of the present description.", "The moving object 2 is displaced at a speed V m in front of lens 1 of the camera.", "Behind the lens is found a unidimensional photosensitive arrangement 5 using a solid state detector, here further called a CCD bar.", "The image of the moving object runs past at the speed Vi in front of arrangement 5.", "FIG. 2 shows how this arrangement is formed which includes a row of elementary pixels 6 arranged side by side.", "The incident light coming from the reference line to be captured produces charges on each of the detectors, which charges represent the intensity profile of a line of the image at a given instant.", "These charges are periodically transferred in the sense of arrows 9 into a shift register 7 bearing as many elements 8 as there are pixels 6.", "A clock signal 12 at TV frequency empties the contents of the line towards amplifier 10 in the form of a video signal 11.", "These video signals are next memorized, then visualized in a manner to represent, in the form of an image, the development in time of the line under observation (finish line for instance).", "Several unidirectional arrangements are presently available on the market.", "They are all equipped with a substantial number of pixels ( >1000) to assure high resolution.", "For further details on this subject, reference may be had to the technical publications of the manufacturers, for instance to the publication concerning the arrangement GH 7801 A of Thomson-CSF.", "Complete cameras may even be obtained from the Fairchild Company under the reference CCD 1100C to 1500C or again from the i2S Company (Bordeaux, France) under the denomination iDC 133.", "In the system which has just been described, it has been seen that the incident light produces charges on the row of detectors 6 which charges are periodically transferred towards the output 10 via a shift register 7.", "Here the transfer frequency is fixed since it is tied to an ordinary television standard.", "In effect, in the cited document is noted a frequency of the images which is 25 units per second, each half image lasting 20 milliseconds.", "From this fact the system described has the merit of employing standard material as far as concerns the camera as well as the monitor and the recorder.", "It is thus inexpensive.", "The system described unfortunately presents at least two major disadvantages which determine that it has never been employed in practice and remains at the stage of a prototype.", "The first difficulty concerns the time of exposure of the pixels which is very small.", "Effectively, according to the European standard, a half image is explored in 20 ms (50 Hz) and each half image includes 312.5 lines.", "It follows that the duration of a line is equal to 20/312.5 0.064 ms=64 μs and that the scan frequency is 1/64 μs, i.e. 15,625 lines per second.", "Thus, in employing a unidimensional photosensitive arrangement with standard TV sweep, each pixel will be excited only during 64 μs per scan.", "This represents an extremely short time which limits the domain of application of the arrangement to scenes presenting substantial lighting, since for average illumination the signal gathered will not emerge at all or very little from the background noise, at least with the means presently available.", "The second difficulty concerns the deformation of the images collected.", "It will be understood in effect that to obtain a non-deformed image, it will be necessary that the speed of refreshing of the photo sensitive arrangement given by the clock signal 12 (see FIGS. 1 and 2) correspond to the speed Vi of the image running past on said arrangement.", "The image collected will be compressed if the speed Vi is greater than the refreshing speed or on the contrary, will be dilated if the speed Vi is less than said refreshing speed.", "An example drawn from practical situations will facilitate understanding of the problem which is posed.", "The CCD bar as mentioned hereinabove includes a multiplicity of pixels of a substantially squared off surface, the side of which measures substantially 13 μm.", "With the standard TV at 625 lines, these 13 μm are scanned as already been said in 64 μs, which corresponds to the image of a moving object which would be displaced at the speed Vi of: ##EQU1## In this case, the scan frequency is adapted to the speed of the race and the images reproduced appear without deformation.", "Now this value corresponds to the speed Vi of an automobile race running in front of the CCD bar.", "Should one now wish, with the same apparatus, to capture the images of an athletics race of which the speed of the image Vi may be estimated to be 26 mm/s, the image collected will be strongly dilated in width deforming the shapes of the athletes to the point of rendering them unrecognizable.", "If one wanted thus to obtain an image without deformation of the athletics race, it would be necessary to lower the scan frequency of the bar which correspondingly will increase the time during which the pixels of the bar are exposed.", "In taking the speed of 26 mm/s and a pixel of 13 μm on one side, one may calculate the exposure time, then the scan frequency to be applied to the bar.", "The exposure time is: ##EQU2## and the scan frequency is 1/500 μs=2,000 lines per second.", "To take another example, the exposure time and the scan frequency would be respectively of 3.25 ms and 307 lines per second if one considered a boating trial where the speed of the image Vi running in front of the bar is on the order of 4 mm/s.", "It follows from what has just been said that in order to obtain a non-deformed image of the course to be timed, it is indispensable to adapt the scan frequency of the bar to the speed of the image running past onto such bar in the same manner as one adapts the speed of film in a system employing a film running past behind a slot (process of photo-finish described in the patent document CH-A-399 028).", "In the arrangement set forth in patent document CH-A 590 581 cited hereinabove, this adaptation is effected only for high speed races such as for automotive vehicles.", "It will be understood that in order to capture the image of an athletics race, not only must the scan frequency of the bar be reduced to the values indicated hereinabove, but further it is necessary to have available a reader (monitor, video recorder) the scan frequency of which is tuned and synchronous with that which explores the bar.", "This will never be the case if one wishes to employ a commercial reader conceived for a single frequency (15,625 lines per second) and established once and for all.", "In order to resolve this problem, it has been proposed to employ a reader having an adaptable frequency.", "One could also propose that the processing and storing of images be effected in a PC.", "Whatever be the chosen solution, it will be necessary to employ a complex and onerous collection of apparatus.", "The patent document EP-A-O 223 119 proposes however an apparatus for capturing the image of sporting races including a pulse generator for controlling the transfer of charges from one sensor to the other, in a manner such that the speed of this transfer is made to correspond to the speed of the image of the race which is passing in front of the arrangement.", "No detail however is given concerning the manner in which the image is reconstructed the text being satisfied to explain that this reconstitution is brought about according to techniques known in television, the line frequency being synchronized with the charge transfer frequency, which implies a monitor and a video recorder which are non-standard.", "The patent document EP-A-0 207 675 likewise proposes a video recording apparatus for sporting races including a one dimensional sensor in the form of a bar.", "The signal gathered at the output of the sensor is converted by an A/D converter into a series of image elements which are stored in a video memory in order to form a plurality of images arranged end to end.", "This system is however limited to the capacity of the memory, typically to 16 TV images as the description indicates.", "Such is due to the fact that in this system there are not two buffer memories alternately working, one in reading and the other in writing as is the case in the invention which will be described hereinafter.", "The patent document US-A-4 133 009 proposes for its part two buffer memories working alternately.", "However, the capacity of these memories is determined by an entire TV image from whence there does not result difficulty in reconstituting the TV image in a standard monitor and video recorder.", "This system cannot be applied to capturing the image of races along with a time scale for one arrives at ambiguities in passing from one image to the other (overlapping) since at no moment is there to be found on the screen the juxtaposition of a plurality of image portions at the same time, so as to bring about a temporal continuity between one of the portions and the portions which precede and follow said portion, as is proposed by the present invention.", "If this invention employs several of the characteristics as described in the three documents which have just been discussed, it is with an entirely different purpose from that pursued by said documents.", "The problem to be solved here results from the fact that as the frequency of image acquisition by the bar is not synchronized with the frequency of visualization, one proceeds with generating portions of an image employing buffer memories, such image portions being next stored in an image memory, then read in a discontinuous fashion by jumping over portions of the image in synchronism with a standard TV sweep.", "Thanks to this arrangement, the images are recorded and visualized by means of a standard commercial recorder and monitor at a scan frequency which is fixed and standardized.", "SUMMARY OF THE INVENTION Thus, the principal purpose of this invention is to offer an apparatus for timing races equipped with a one-dimensional CCD bar which is adapted to several speeds of races without deforming the image and while employing a simple image sensor, operating to the ordinary television standard which is currently obtainable on the market.", "Thus with this system the monitor and the video recorder are inexpensive and contribute accordingly to reduce the price of the overall apparatus assembly.", "To obtain this result, the apparatus of the invention is notable in that it includes: means for reading the contents of the bar at a predetermined frequency chosen as a function of the speed of the race, said contents showing up in the form of an electrical signal corresponding to the intensity profile of the line image at a given instant;", "first and second buffer memories alternately adapted to memorize a predetermined number of electrical signals resulting from successive readings of the bar in order to form respectively first and second image parts of the race;", "means for alternately transferring said first and second image parts into an image memory adapted to store n image parts of substantially equal capacity, the apparatus being arranged in a manner such that, when the first buffer memory stores the signals issuing from the bar, the image part contained in the second buffer memory is written into the image memory and vice-versa, said image memory exhibiting at the time of each writing an image part in the course of writing and n-1 image parts already written;", "means for reading in accordance with a predetermined order said n-1 parts already written into the image memory in a manner such that the first image part read corresponds to the part freshest in time already written into the image memory and so on in accordance with a chronological order;", "a monitor of standard TV type for displaying on a screen the n-1 image parts read in the image memory in a manner such that, at the time of each writing of a new image part into the image memory, the freshest portion appearing on the screen takes the place of the preceding portion, this latter undergoing a jump displacement so as to be placed beside said freshest portion, and a recorder of standard TV type for recording the images appearing on the monitor.", "The invention will now be set forth with the aid of the following description illustrated by way of example by the drawings.", "BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 represent the prior art as discussed hereinabove;", "FIG. 3 is a block diagram illustrating the invention according to a simplified embodiment permitting solely the acquisition of images and including essentially two buffer memories and an image memory;", "FIG. 4 is a graphical illustration of how from portions of the image stored in an image memory one constructs a complete image visible on a monitor;", "FIG. 5 is a block schematic showing the invention according to a more developed embodiment permitting, in addition to the acquisition of images, the inscription of the time corresponding to the images;", "FIG. 6 is a graph showing partially the graph of FIG. 4 to which a time scale has been added;", "FIG. 7 is a timing diagram applicable to the block schematic of FIG. 5 showing the progress of image acquisition and FIG. 8 shows how the buffer memories and the image memory are organized as well as the manner in which the signals of said buffer memories are transferred to said image memory.", "DESCRIPTION OF THE PREFERRED EMBODIMENT The block schematic of FIG. 3 shows a simplified embodiment of the invention.", "Here runners 2 each progressing in a corridor 4 at a speed Vm cross in turn a passage line 90 which may be the finish line of the race.", "In the prolongation of this passage line is located an optical arrangement or lens 1 forming part of a camera 15.", "The image of the line 90 is formed on a photo sensitive bar 5 which is located behind the lens 1.", "In a plane perpendicular to FIG. 3, bar 5 is as illustrated on FIG. 2 and is comprised of a plurality of pixels juxtaposed in a single column.", "The image of the runner runs past at speed Vi in front of the bar.", "A time base or timer 25 coupled to the camera by connection 35 enables reading the contents of the bar at a predetermined frequency, each reading being followed by a refreshing of the bar.", "The reading frequency is chosen to correspond to the speed Vi of the image of the race.", "It is understood thus that at any given instant the contents of the bar existing in the form of an electrical signal is found to be equal to the intensity profile of the image of line 90.", "The reading frequency of the bar is chosen by the operator of the apparatus as a function of the speed of the race for which he must retain the images.", "For this the operator has available a keyboard 27 on which he may introduce manually the value of such speed.", "A microcontroller 26 serves as an interface between keyboard 27 and the time base 25, which permits to derive from the time base --generally furnishing the time of day--the reading frequency chosen by the operator.", "Likewise from the keyboard the operator may signal the person responsible for giving the starting signal of the race that the apparatus is ready to receive images of the race.", "This signal issues from the time base 25 via the line R (ready).", "Inversely, the time base 25 of the apparatus may be reset to zero, then started by the starting signal of the race and this by the line S (start).", "It should be mentioned that the time base 25 and the microcontroller are circuits obtainable in commerce, for instance under the designation Intel 80186 which combines blocks 25 and 26 in a single integrated component.", "The electrical signals resulting from the successive readings of the bar 5 are memorized initially in a first buffer memory 19 via a switch 28 set according to the position shown on FIG. 3. In the embodiment taken as example, when 128 columns including 512 pixels have been memorized in buffer 19, timer 25 switches the output of the bar onto the input of a second buffer memory 20 which memorizes in turn 128 new columns captured by the bar.", "One is thus in the presence of image portions each including 128 columns.", "In the example of a sweep of 2,000 columns per second, each portion of the image thus represents a race time of 128/2,000=64 ms.", "FIG. 3 shows that the contents of buffer memories 19 and 20 may be alternately led via another switch 29 to an image memory or video RAM 21.", "This switch is controlled by timer 25.", "It is seen that when the buffer memory 19 stores the electrical signals coming from bar 5, the content of buffer memory 20 is transferred into the image memory 21 and vice-versa.", "For this it is understood that switches 28 and 29 are operated in synchronism and controlled by timer 25.", "It will here be noted that the buffer memories are capable of storing 128 columns, each comprising 512 distinct signals.", "These may be memories of the type Hitachi HM 62536.", "The image memory 21 has a capacity sufficient to memorize n portions of the image coming from the buffer memories 19 and 20.", "When the apparatus operates and at each instant of its operation, it will be understood that the memory image presents one portion of image in the course of being transferred or writing in and n-1 portions of image already transferred or already written.", "Such a memory may be of the type Intel 514256.", "By means of a video controller 24--which may be of the type Intel 82786--one next reads according to a predetermined order the n-1 portions of the image already written into the video RAM 21 in a manner such that the first portion of the image read corresponds to the freshest temporal portion written into said video RAM and so on according to chronological order.", "Next the images read according to the order indicated hereinabove are displayed on a monitor 23 of ordinary TV standard and parallelly registered in a recorder 22 of ordinary TV standard in a manner such that after each writing of a new image portion into the image memory 21 the freshest portion displayed on the screen of the monitor 23 takes the place of the portion previously displayed, this latter undergoing a displacement by jump in order to be placed beside the freshest portion.", "Should one wish for a time increase extending from left to right on the screen, it will be arranged so that the freshest portion of the image appearing on the screen is found to the right of such screen, the display of a new portion of the image displacing the portion of the image which was previously found there toward the left.", "There it concerns an image reconstruction from several partial images, each of said partial images including in the embodiment taken as an example 128 columns.", "How the operation of the synchronization with an ordinary TV standard is brought about will be explained hereinafter when a more complete embodiment of the invention is discussed.", "FIG. 4 will facilitate understanding of the reconstruction mechanism of the image as mentioned hereinabove.", "Reference 21 designates the image memory and reference 23 the monitor screen.", "The image memory may contain five portions of the image represented by five compartments numbered 1 to 5.", "There is initially the transfer of the contents of the buffer memory 20 (see FIG. 3) into the image memory 21.", "The runner 70 is then written into compartment 1.", "Following this transfer, one reads compartments 2 to 5 of the image memory and one displays them on the monitor.", "In the example, compartments 2 to 5 of the memory being empty of information, the monitor will not display any information (FIG.", "4a).", "When the buffer memory 19 is entirely filled by the image portion acquired from bar 5, switches 28 and 29 change position and the content of buffer 1 is transferred into compartment 2 of the image memory: the runner 71 is written into compartment 2.", "Following this writing in one reads in order 3, 4, 5 and 1, the compartments of the image memory.", "The runner 70 appears to the right of the monitor screen 23 (FIG.", "4B).", "During the following stage shown on FIG. 4C, there is a new acquisition in the compartment 3 of the image memory, which acquisition is determined by runner 72.", "Following this acquisition, one reads again the compartments already written from the image memory in a manner such that the first image portion read corresponds to the portion which in time is the freshest already written into the memory.", "Here it concerns runner 71 followed by runner 70 and the two empty compartments 5 and 4.", "There then appears on the monitor screen from right to left the runners 71 and 70, the runner 70 being displaced towards the left in order to leave its place to the new arrival 71.", "During the following stage (FIG.", "4D), it is runner 71 which is transferred into the image memory 21 bringing about the display on the monitor screen 23 of runners 72, 71 and 70.", "The process continues thus as shown on FIGS. 4E and 4F.", "It is to be noted on FIG. 4F that the transfer of the new runner 74 into the image memory has chased from the screen the first runner 70 which no longer appears thereon.", "In the example shown here, one sees that the image memory may contain five image portions (n=5) and that the monitor screen displays four of these portions (n-1=4).", "It will be noted that the invention is not limited to this arrangement and that n may be different from 5.", "What precedes has explained the general principle of the invention, to wit how one constructs a complete image from image portions which are displaced by jumps as their acquisition progresses.", "Here it concerns however a much simplified version of the invention which does not enable appreciation of the rank of the runners.", "As in most cases, in addition to the necessity of separating the runners according to the rank which they occupy, it is indispensable to determine the time taken by each competitor in order to traverse the space separating the starting line from the line under control;", "it is necessary to attach to the race image a time scale corresponding to these images.", "FIG. 5 shows a perfected embodiment of the invention which takes up all the elements discussed in respect of FIG. 3 in adding to them elements enabling the creation of a time scale and other elements bringing certain advantages which will appear upon reading the lines to follow.", "Camera 15 summarily schematized on FIG. 5 includes a bar 5 of at least 512 pixels arranged in a column.", "The signals coming from the bar are amplified by an amplifier 16 of which the gain may be varied, for example as an automatic function of the lighting of the objective to be sensed.", "A first converter 17 transforms the analog signals coming from amplifier 16 into digital signals, each pixel being represented by 8 bits (=1 byte).", "The first six bits encompass information relative to 64 grey levels of pixel, the last two being employed for instance for transmitting information relative to the colour of the pixel.", "The camera is controlled by a controller 18 from whence are issued for instance the scan frequency of the bar (line 49), the gain control of the amplifier (line 50) and the converter control (line 51).", "Controller 18 receives signals from the time base 25 (line 35) and is coupled to the microcontroller 26 by a bidirectional line 61.", "It has been mentioned hereinabove that this camera may be bought already complete from the company i2S (Bordeaux, France).", "The signals coming from camera 15 by line 91 are led to switch 28 in order to alternately feed the buffer memories 19 and 20 as has already been explained hereinabove.", "In the same manner, from the moment that a buffer is filled, its contents are written into the image memory 21 via switch 29 and line 55.", "The signals gathered at the output of the image memory are led via line 54 to a second converter 43 which converts the digital signal coming from the image memory into an analog signal which, via lines R, G, B is led to an encoder intended to link the system to readers (monitor and video recorder) of a standard type according to the ordinary standard colour TV.", "It will be mentioned that one may employ for the second converter 43 the Booktree BT 478 circuit and for the coder the Motorola MC 1377 circuit following the PAL or NTSC standard.", "A Philips circuit TDA 2506 would enable adaptation to the SECAM standard.", "The other elements (buffers, image memory, timer, microcontroller) are of the same type as those already mentioned hereinabove.", "The schematic of FIG. 5 is to be noted in the sense that it enables creation of a graphic time scale with digital references enabling easy reading of the race time.", "The graphic generator is represented at 39.", "It forms, together with the video controller 24 already mentioned in connection with FIG. 3 and a video address generator 40, a unique component 60 which is of the type Intel 82786 already identified.", "The construction of the image is brought about in the same manner as that discussed with reference to FIGS. 3 and 4 with a time scale in addition.", "FIG. 6 shows a special situation taken at the same moment as that represented on FIG. 4c.", "The image memory 21 includes a zone image 81 comprising runners 70, 71 and 72.", "This zone includes five portions, each composed of 128 columns, each column itself comprising 480 bytes.", "The image memory 21 includes further a time scale zone 82 comprising time subdivisions 92 and a writing arrangement 93 labelled in minutes, seconds and tenths of a second (for example 1'13"20).", "This zone likewise includes five portions, each composed of 128 columns, each column including 32 bytes.", "In FIG. 6, the runner 72 is in the course of being written into the image memory and the runners 71 and 70 have already been written into said memory.", "It follows that there appear on screen 23 runners 71 and 70, the runner 71, the most recently acquired, appearing at the right of the screen.", "If one traces straight lines 105 and 94, which moreover are applied to form a cursor which will be discussed subsequently to the vertical of the position of the runners, one will find that the runner 70 has crossed the space separating the starting line from the line under control in a time equal to 1'13"15, while runner 71 has traversed the same space in a time equal to 1'13"213, the runner 70 preceding thus by 6.3 hundredths of a second runner 71.", "FIG. 7 is a timing diagram which will facilitate understanding of the arrangement of the schematic of FIG. 5. Line A of FIG. 7 indicates the time scale, 20 milliseconds separating two divisions.", "Line B indicates in the ordinary standard TV 625 lines and, referenced by 1, 2, 3 etc.", ", the succession of half images each being of 20 ms.", "The readers (monitor 23 and recorder 22) respond to this standard in the example chosen here.", "From the camera 15 one acquires the images at a rate that one chooses at 2,000 columns per second, which corresponds to the athletics race mentioned hereinabove.", "The time for filling a buffer memory 19 or 20 will thus last 128/2,000=64 ms, which is shown on lines C and D of the diagram of FIG. 7. When buffer 1 is in acquisition, switches 28 and 29 occupy the position drawn on FIG. 5 and buffer 2 is in the situation of being able to transfer its contents to the image memory.", "When buffer 1 is filled, the timer 25, via an address generator the role of which will be explained further on, causes switches 28 and 29 to reverse roles via line 30.", "Buffer 1 may then be transferred into the image memory (arrow 95).", "This transfer is shown by line E of the graph of FIG. 7. The figure shows that the transfer does not take place immediately, but only in synchronization with the beginning of the scan of the half image following immediately the end of the filling of buffer 1, as it happens the beginning of the half-image 5 of the line B. At the end of this operation the 128×512 bytes of the buffer 1 are present in the image memory and the transfer time will have lasted during the time shown at 96 on line E. The portion of the image memorized in the image memory may then be visualized on the monitor screen.", "This visualization commences from the beginning of the scan of a half-image following immediately the end of the transfer into the image memory (arrow 97), as it happens at the beginning of the half-image 6 (line B) and stops at the end of the half-image 8 from which it is the buffer 2 transferred by 98 into the image memory which is visualized on the screen according to the same process as that explained hereinabove with reference to buffer 1.", "It will next be noted that the portions 1, 2, 3 etc.", "visualized on the screen (line G) are then completely synchronized with ordinary standard TV images.", "The figure shows that portions 1, 3, 4 and 5 last 60 ms and portion 2 lasts 80 ms.", "If one were to continue the graph, one would find new portions at 80 ms, for instance that which would be the portion 7 of line G. One thus finds the portions of the visualization of which the duration of immobilization on the screen covers three, respectively four half-images, which corresponds to at least one complete TV image in the first case and two complete images in the second case.", "One will add to this that this transfer of the image portion contained in the buffer towards the video RAM 21 will be effected during the TV lines which are not used, i.e. in the example and for one image during 625-512 =113 lines.", "This transfer must be synchronized with the image frequency or interlace frequency and one will have available to bring this about at most three half-images.", "The graph of FIG. 7 shows a transfer brought about once, but one will understand that it could be effected three times.", "Such being the case, the transfer time available is 113·64 μs·3/2=10,848 μs, if 64 μs is the duration of a line in 625 line TV.", "This time will permit calculating the transfer time of one byte which is of 10,848 (128·512) 0.165 μs, which time is entirely compatible with the memories presently available on the market.", "FIG. 7 further shows in line H the creation of the time scale.", "While buffer 1 is loaded in images acquired from the bar, graphic generator 39 of FIG. 5, coupled to timer 25 by line 52, generates a scale of times synchronized with the columns acquired from the bar.", "At the beginning of the acquisition of an image portion, the race time or time of day is read on a chronometric counter.", "Knowing the time of origin of a portion and the time increment for each column of such portion, the graphic generator has available sufficient information to trace the time scale for the 128 columns of one portion.", "To accomplish this work, generator 39 has available at least 64 ms, the duration for filling a buffer memory from which duration it is necessary to subtract the transfer time of the graphic data in the video RAM.", "The pixels thus generated are temporarily deposited in a graphic RAM memory of 128×32 pixels forming an integral part of the graphic generator 39.", "This information is next transferred to the image memory 21 by line 53 at the end of the image data coming from one of the two buffers 19 or 20.", "The diagram of FIG. 7 shows that the transfer 96 of an image portion is followed by transfer 99 (line I) from scale 1 into the image memory (arrow 100).", "As soon as this transfer has taken place, the graphic generator is again available for the creation of the following scale, as it happens, scale 2 (arrow 101).", "Finally, the first portion of the image to appear on the screen is complete with the image of the race in the upper zone 83 and the time corresponding to the image of the race in the lower zone 85 as shown by line J of FIG. 7. FIG. 5 further shows a switch 37 controlled by the video controller 24 over line 58.", "It will be understood that when the image memory 21 is in the read mode (transfer of data towards the visualization screen), switch 37 is positioned as shown on the figure, while when such memory is in the write mode, the switch couples lines 34 and 57 of the schematic.", "Graphic generator 39 may furnish information other than that relative to the time.", "It is thus that in the writing zone there could appear for each image portion an order number indicating in an increasing manner the order in which these portions are acquired, which would permit facilitating the locating thereof.", "The graphic zone could also bear a text identifying the race with which one is concerned.", "In addition to what is shown on FIG. 3, FIG. 5 further shows an address generator 38 which acts directly on buffers 19 and 20 by line 36.", "The buffer memory used here stores the pixels, the ones behind the others, as is seen by reference 19 on FIG. 8. Pixel 1 of column 1 is followed by 128×512 pixels to end up at pixel 65536 of column 128.", "It follows that this type of memory is not organized to be read according to a horizontal scan associated with the ordinary standard TV.", "It is the role of the address generator to proceed to transfer the pixels into the image memory according to an order compatible with such ordinary TV standard.", "FIG. 8 shows at 21 a portion of memory 21 organized in a suitable manner.", "The schematic of FIG. 5 shows a video recorder 22.", "It is seen that image generation proceeds in a discontinuous fashion by jumps of 128 columns.", "This is in fact not troublesome since the images are sent to the video recorder 22, then exploited in a deferred manner in the image by image mode.", "Furthermore, apart from the utilization in image by image, other functions associated with such a recorder may find a utilization of interest, in particular the digitalization of the image, the zoom image in image and the research for the good image sequence, etc.", "Keyboard 27 of FIG. 5 enables several important functions such as: initialization of the system, date, time of day, graphic representation mode, colours, etc.", "introduction and memorization of several titles;", "introduction of parameters, for example acquisition speed;", "gain, camera diaphragm;", "priming the start for the chronometric counter;", "beginning and end of acquisition;", "specific orders to the VCR such as positioning of the tape, search for the proper sequence image by image, stop on an image, recording, reading, etc.", ", this as a function of the VCR possibilities;", "control of the cursor on the screen.", "The latter is shown only in read mode;", "preparation of titles.", "The cursor just mentioned hereinabove is created by a cursor generator 41 which appears on FIG. 5. This generator is adapted to generate a vertical bar of small thickness on the image displayed by the monitor and traversing the image from top to bottom.", "This bar may be horizontally displaced so as to attribute a time to a chosen point of the image.", "This cursor generator may be obtained simply by means of a ramp generator and a voltage reference to be compared therewith.", "The cursor width will be chosen to be on the order of two pixels.", "The examples given hereinabove are based on a European standard of 625 lines.", "It will be understood that the invention may be applied by analogy to other standards, for instance to the American standard of 525 lines." ]
This application is a division of Ser. No. 08/142,873 filed Oct. 28, 1993. BACKGROUND OF THE INVENTION This invention relates to a high efficiency encoding device and a noise spectrum modifying device and method for speech or audio signals. More particularly, it relates to a high efficiency encoding device and a noise spectrum modifying device and method of the sub-sampling encoding system, such as MUSE, in which the quantization noise spectrum is rendered aurally acceptable by reducing the noise level as perceived by the ear to improve the quality of the speech or audio signals for high definition telecasting. As a system for high efficiency encoding of digital audio signals there has hitherto been proposed a system consisting in the combination of differential encoding and near-instantaneous compression. According to the proposed system a difference between two neighboring samples of the digital audio signals is compressed on a block unit basis, by way of near-instantaneous compression, using range information as found based on a maximum value of the difference in a block consisting of a pre-set number of samples. There has also been disclosed in JP Patent KOKAI Publication No. 63-16718 (1988) a technique in which the difference is found based on a difference between signals of the current sample and signals of a directly previous sample restored by processing with near-instantaneous compression, near-instantaneous expansion and accumulation to correct the errors produced at the time of the range compression. Such high efficiency encoding system, consisting in the combination of the differential encoding and near-instantaneous compression and expansion (compansion) is employed for encoding audio signals processed with bandwidth compression by the multiple subsampling encoding system, such as MUSE, for telecasting or recording on a recording medium, such as a recording disc, of high definition television signals, such as so-called high-vision signals. FIG. 1 shows characteristics in the high-efficiency encoding by the above-described conventional combination of the differential encoding and near-instantaneous compansion. In FIG. 1, curves A and B represent an output signal level and a noise level, respectively. Thus it is seen that the S/N ratio is lowered towards higher frequencies at a rate of 6 dB/oct. The quantization noise shows a substantially flat spectrum. The status shown in FIG. 1 is not fully satisfactory as long as the aural sense of human being is concerned, although a minimum noise energy may thereby be achieved. Above all, the S/N ratio is lowered when the high-range signal is supplied as an input signal. OBJECT AND SUMMARY OF THE INVENTION In view of the above-described status of the art, it is an object of the present invention to provide a high efficiency encoding device, a noise spectrum modifying device and method whereby, when encoding audio signals by the combination of the differential encoding and near-instantaneous compansion, the quantization noise as perceived by the ear may be reduced to improve the sound quality without changing the existing format. For accomplishing the above object, the present invention provides a high efficiency encoding apparatus comprising difference signal outputting means having a local demodulating function, quantization means having a near-instantaneous compansion and noise-shaping means for modifying the spectrum of the quantization noise. It is preferred for the noise shaping characteristics of the noise shaping means to be substantially the equal-loudness characteristics normalized with the critical bandwidth. It is also preferred for the noise shaping characteristics to be substantially flat for a frequency region not higher than 4 kHz. It is similarly preferred for the noise shaping characteristics of the noise shaping means to be obtained by mixing the characteristics substantially similar to the equal-loudness characteristics normalized with the critical bandwidth and the masking threshold characteristics, while it is also preferred for the masking threshold characteristics to be mixed at a higher proportion with and increase in the input signal level. Thus the present invention consists of modifying the spectrum of the quantization noise so that the noise as heard by the ears becomes lower. To this end, error feedback may be employed. The equal-loudness characteristics and masking characteristics may be employed for reducing the noise as heard by the ears. The concept of the critical bands may be employed in converting the equal-loudness characteristics into characteristics of the noise spectrum. According to the present invention, the quantization noise as perceived by the ears may be reduced by taking into account the equal loudness characteristics and masking characteristics by the noise shaping means which modify the spectrum of the quantization noise. That is, the noise level as perceived by the ears may be reduced in a manner desirable for the sound quality without modifying existing formats, such as the speech format for high definition telecasting or recording on the recording medium by the so-called MUSE system or the decoders. With the high efficiency encoding apparatus according to the present invention, comprising difference signal outputting means having a local demodulating function, quantization means having a near-instantaneous compansion function and noise-shaping means for modifying the spectrum of the quantization noise, the quantization noise as perceived by the ears may be reduced by taking into account the equal-loudness characteristics and the masking characteristics by the noise shaping means which modifies the quantization noise spectrum. It should be noted that the characteristics of the noise filter provided in the noise shaping means are set on the basis of at least one of the characteristics based on the information of the equal-loudness characteristics and the masking characteristics as obtained from the information derived from the frequency analysis of the input audio signal and, if both of them are employed, a synthesis ratio between the characteristics based on the information of the equal-loudness characteristics and the masking characteristics as obtained from the information derived from the frequency analysis of the input audio signal is set based on the information which is changed depending on the input audio signal level. It becomes possible in this manner to reduce the noise as perceived by the ears to improve the dynamic range as far as the aural sense of the human being is concerned. Therefore, if the high efficiency encoding device for audio signals according to the present invention is applied to, for example, standardized digital audio equipment, it becomes possible to produce the playback sound having a higher dynamic range than that actually realized under the unified standard as long as the aural sense of the human being is concerned. For example, the dynamic range of the reproduced audio signal as perceived by the ears may be improved under maintenance of the existing unified standard, that is, under maintenance of compatibility without modifying the playback side arrangement. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing signal-to-noise characteristics of a conventional high efficiency encoding device for audio signals. FIG. 2 is a block diagram showing a processing device according to a first embodiment of the present invention. FIG. 3 is a graph showing noise-shaping characteristics for reducing the aurally perceived noise level. FIG. 4 shows typical examples of the relation between the center frequencies of the critical bands and the bandwidth. FIG. 5 is a graph showing the relation between the noise shaping characteristics of the embodiments of the present invention and the equal loudness curve as normalized with the bandwidth of the critical bands. FIG. 6 is a block diagram showing a processing device according to the second embodiment of the present invention in which the equal loudness characteristics and masking characteristics are taken into account. FIG. 7 is a graph showing masking characteristics for a sine wave input. FIG. 8 is a graph showing masking characteristics by plural spectral components. FIG. 9 is a graph showing equal loudness characteristics and comprehensive masking characteristics by plural spectral components. FIG. 10 is a graph showing a frequency response for low-range input signals having a slightly high signal level. FIG. 11 is a graph showing a frequency response for low-range input signals having a high signal level. FIG. 12 is a graph showing a frequency response for high-range input signals having a slightly high signal level. FIG. 13 is a graph showing a frequency response for high-range input signals having a high signal level. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, a first embodiment according to the present invention will be explained in detail. In FIG. 2, a digital speech or audio signal, supplied to an input terminal 11, is transmitted to a subtractive node 12 and to a one-sample delay unit 13. A delay signal from the one-sample delay unit 13 is transmitted to the subtractive node 12 so that a difference signal between neighboring samples is outputted from the subtractive node 12. The difference signal is transmitted to a range detector 14 for sequentially detecting the signal levels in the course of a given block. The maximum level as detected during the one-block interval is used for determining the compression range of the difference signal for the block. The range signal from the range detector 14 is held for the one-block interval by a one-block holder 15 before being outputted at a range output terminal 16. The input signal at the input terminal 11 is also delayed by one block by a one-block delay unit 17 and thence supplied via a difference unit 20 to an annexed noise shaping circuit 21 for noise shaping, from which the noise-shaped signal is restored via a near-instantaneous compressor 26, a near-instantaneous expander 27 and an accumulator 28 and thence supplied to the difference unit 20 for difference taking. A delayed output of the one-block delay unit 17 is supplied to a fixed terminal a of a changeover switch 18, while an output signal of the near-instantaneous compressor 26 is transmitted to a fixed terminal b of the changeover switch 18. An output of the changeover switch 18 is issued at a difference signal output terminal 19. In the first embodiment of the present invention, there is annexed the noise shaping circuit 21 having a subtractive node 24 for finding a difference between an input to the near-instantaneous compressor 26 and an output of the near-instantaneous expander 27 for taking out only the quantization noise which is processed with a filter 23 consisting of a first-order linear coupled circuit before being fed back via an additive (subtractive) node 22. The transfer characteristics of the first-order linear coupled circuit constituting the filter 23 are generally represented as Σa n z -n . The noise-shaping characteristics for a typical set of coefficients of the first-order linear coupled circuit, which represent the equal-loudness characteristics normalized by the critical band width, are shown in FIG. 3, in which curves A and B denote the equal-loudness characteristic curve and the noise-shaping characteristic curve normalized with the critical band widths, respectively. That is, the equal-loudness characteristics A and the noise shaping characteristics B represent the subjective magnitude of sine wave signals at each frequency and the noise spectrum, respectively. Consequently, it becomes necessary to establish the relation of matching between the subjective magnitude of the sine wave signals and the subjective magnitude of the noise. This may be achieved by relying upon the concept of the critical band. That is, the noise shaping characteristics capable of affording the noise spectrum matched to the equal loudness characteristics may be obtained by calculating the pure energy of the noise in each critical band and coinciding the calculated energy with the equal loudness level of the sine waves at the center frequency of each critical band. Since the critical band width becomes broader for the higher frequency, it is unnecessary for the noise shaping characteristics to be increased as strongly as the equal loudness characteristics towards higher frequencies. FIGS. 3 and 4 illustrate typical characteristics and the typical numerical relation between the center frequencies and the bandwidth of the critical bands, respectively. In FIG. 5, in which the critical band numbers (Bark) are plotted on the abscissa, there are shown an equal loudness characteristic curve A normalized with the critical band widths and a noise shaping characteristic curve B according to the present invention. The noise shaping characteristic curve B according to the present invention is adjusted so as to be coincident with the equal loudness characteristic curve at the frequencies approximately equal to 4 kHz and higher. At the frequencies lower than 4 kHz, the noise shaping characteristics may be drawn closer to flatness for lowering the number of orders of the digital filter. Referring to the drawings, the second embodiment of the present invention will be explained. FIG. 6 shows, in a block diagram, a schematic arrangement of a second embodiment for reducing the quantization errors for audio signals. The device shown in FIG. 6 is a high efficiency encoding device including a noise shaping circuit which also takes the masking effects into account. The device shown in FIG. 6 is designed to feed back the quantization errors produced in the near-instantaneous compressor 26 to the input side of the near-instantaneous compressor 26 via, among other things, a noise filter 23, and comprises a level detection unit 34 for detecting the level of the input audio signal, a frequency analysis unit 31 for performing frequency analysis of the input audio signal from one critical band to another, an equal loudness curve generating unit 35 for generating the information conforming to the human auditory sense based on the so-called equal loudness curve shown in FIG. 5, and an allowable noise spectrum calculating unit 33 for changing the synthesis ratio between the output of the equal loudness curve generating unit 35 and the output of the masking characteristic processing unit 32 for realization of the optimum quantization noise spectrum by the output of the frequency analysis unit 31 depending on the output of the level detecting unit 34 for calculating the allowable noise spectrum based on the resulting synthesis information. The device shown in FIG. 6 is designed to set the filter characteristics of the noise filter 23 based on the output information of the allowable noise spectrum calculating unit 33. That is, in the present embodiment, a so-called error feedback circuit is made up of the subtractive node 24 for subtracting the input to the near-instantaneous compressor 26 from the output of the near-instantaneous expander 27 for producing a quantization error generated at the time of quantization at the quasi-instantaneous compressor 26, the noise filter 23 for filtering the output of the subtractive node 24 to output the filtered output, and an additive node (subtractive node) 22 for adding the output of the noise filter 23 to the input of the near-instantaneous compressor 26. The filter characteristics of the noise filter 23 are determined by calculating filter coefficients by a filter coefficient calculating unit 36 based on the information of the allowable noise spectrum information of the allowable spectrum calculating unit 33 as later explained and by transmitting the filter coefficient information to the noise filter 23. Thus the error feedback circuit performs the quantization error reducing operation (so-called noise shaping) based on the allowable noise spectrum, as later explained, and the output of the error feedback circuit is subsequently issued at an output terminal 19. The construction and the operation are otherwise the same as that of the first embodiment shown in FIG. 2 so that the corresponding parts are indicated by the same numerals and the corresponding description is omitted. Meanwhile, when the quantization error reducing operation (noise-shaping operation) is to be performed by the above-described error feedback circuit, the dynamic range of the audio signals as perceived by the human aural sense may be increased by a processing which takes the masking of the input signal spectrum into account. As the noise shaping taking the masking into account, there are a noise shaping conforming to the signal spectrum of the input audio signal having a more or less fixed pattern, that is a noise shaping which makes use of the allowable noise spectrum produced by taking the so-called masking of the input audio signal spectrum into account, and a noise shaping which makes use of the allowable noise spectrum which is adapted to changes in the spectrum of the input audio signals and which is obtained by taking the masking of the spectrum into account. By the masking is meant the phenomenon in which, owing to the aural feature of a human being, a signal becomes masked by another sound and becomes inaudible. Among the masking effects, there are a masking effect on signals on the time domain and a masking effect on signals on the frequency domain, that is a concurrent masking or a temporal masking. Due to the masking effects, any noise present in a masked region becomes inaudible. As for the concurrent masking effect as shown in FIG. 7, if the frequency response of a signal S at a given frequency is 0 dB, a masking effect acts in a region below a curve M (for approximately -25 dB or lower) by the signal S. Besides, if the input signal is segmented according to the critical bands to take advantage of the auditory sense characteristic of a human being and the noise shaping is performed by employing the allowable noise spectrum taking the above-mentioned masking into account for each critical band, the noise shaping which is more effective for the auditory sense characteristic of a human being may be achieved. It becomes possible in this manner to improve the dynamic range of the reproduced sound as perceived by the ears. Thus the frequency analysis unit 31 segments the input audio signals by the so-called critical bands by taking advantage of characteristics of the human auditory sense and performs frequency analysis for each of the critical bands. In segmenting the input audio signal by the critical bands, it is possible to translate the input audio signal into components on the frequency domain (FFT coefficients) by e.g. the fast Fourier transform (FFT) and to classify the amplitude terms Am of the FFT coefficients, m being 0 to 1024, into e.g. 25 bands or groups Gn, n indicating the band or group numbers and being 0 to 24, in accordance with the above-mentioned critical band widths which become broader towards higher frequencies for taking account of the characteristics of the human auditory sense. By way of the frequency analyses for each of the critical bands, a so-called Bark spectrum Bn or the spectrum of total sums, which may be found by finding the total sum of the amplitude terms Am (total sum of the peaks, mean values or energies) for the respective bands, may also be found in accordance with the equation (1): Bn=10 log 10 Cn(Pn)2 dB (1) In the equation (1), n=0 to 24, Cn is the number of elements that is the amplitude terms (number of points) in the n'th band, and Pn is the peak value for the respective bands. A typical Bark spectrum for the respective bands is shown in FIG. 8, in which the number of the critical bands is set to 12 (B1 to B12) for brevity. The frequency analysis unit 31 performs the division by the critical bandwidth and the frequency analysis from one critical band to another and transmits the output information to the masking characteristics calculating unit 32. The equal loudness curve generating unit 35 generates and outputs the information which is the equal loudness curve normalized with the critical bandwidth. The equal loudness curve represents aural characteristics of human being and is obtained by interconnecting the sound pressures of the sounds at the respective frequencies heard with the equal loudness as a pure sound of 1 kHz. It is also known as the equal loudness sensitivity curve. As shown by a curve RC of FIG. 9, representing the equal loudness curve, the hearing power of human being is strongest in the vicinity of 4 kHz, such that the sound of 4 kHz is heard with substantially an equal loudness as the 1 kHz sound even if the sound pressure is lower by e.g. 8 to 10 dB than the 1 kHz sound, while the sound of e.g. 10 kHz is less audible by about 20 dB than the 4 kHz sound. Consequently, the dynamic range of the reproduced sound as perceived by the ear may be improved by noise shaping the audio signals by the error feedback circuit based on the curve RC which is the equal loudness curve normalized with the critical bandwidth. That is, by performing the noise shaping using the allowable noise spectrum obtained by taking into account the curve RC which is the equal loudness curve normalized with the critical bandwidth, noise shaping more effective in view of the aural sense of human being may be realized to improve the dynamic range of the reproduced sound as heard by the listener. The information concerning the curve RC, which is the equal loudness curve normalized with the critical bandwidth as perceived by the ear, or a curve approximated to the curve RC, is outputted by the equal loudness curve generating unit 35 so as to be supplied to the allowable noise spectrum calculating unit 33. The allowable noise spectrum calculating unit 33 calculates the allowable noise spectrum based on the output information from the equal loudness curve generating unit 35 and the output information of the masking characteristics calculating unit 32. At this time, the Bark spectral components Bn for the respective critical bands produced by the frequency analysis unit 31 are convolved to take into account the effects of the neighboring bands in accordance with equation (2) Sn=Hn*Bn (2) wherein Hn denotes convolution coefficients, for calculating the convolved Bark spectrum Sn for the respective bands. By the convolution, the sum total of dotted-line portions in FIG. 8 is found. Then, using the convolved Bark spectrum Sn and the S/N value On as required, n being equal to 0 to 24, the masking threshold Tn resulting from convolution is calculated by equations (3) and (4): On=K-Kxn (3) Tn=Sn-On (4) For example, it can be set that K=1 for N=38, in which case the deterioration in the sound quality is diminished. That is, as shown in FIG. 10, the level lower than the levels of the convolved masking threshold Tn is masked. The convolved masking threshold Tn is subsequently deconvolved by equation (5): TFn=Tn-Dn (5) to calculate the allowable noise level (allowable noise spectrum) TFn. In effect, the dc gain Dn of the convolution by the coefficient Hn is subtracted from Tn. The allowable noise spectrum calculating unit 33 calculates the allowable noise spectrum based on the information obtained by combining the output information of the masking characteristic calculating unit 32 with the output information of the equal loudness curve generating unit 35. Meanwhile, it may occur that the allowable noise level with the allowable noise spectrum based on the curve RC which is the equal loudness curve normalized by the critical bandwidth becomes lower than the allowable noise level by the masking effects which depends on the input signal level. That is, with the higher input audio signal level, it may occur that the level of the allowable noise level based on the equal loudness curve is simultaneously masked by the allowable noise level by the masking effect which depends on the input audio signal. Thus, with the present embodiment, the input audio signal level is detected by the level detecting unit 34 and the synthesis ratio of the output information of the equal loudness curve generating unit 35 and the output information of the masking characteristic calculating unit 32 is changed depending on the detected output level. It is noted that the synthesis of the output information of the equal loudness curve generating unit 35 and the output information of the masking characteristic calculating unit 32 is carried out from band to band. In such case, level detection by the level detection unit 34 is also made from band to band so that the synthesis ratio is changed from band to band depending on the band-based detected output level. That is, if the low-range input audio signal is high such that the masking effect for the low-frequency range is high, the synthesis ratio employed for producing the synthesis information for finding the allowable noise spectrum by the allowable noise spectrum calculating unit 33 is of such a value as to give an allowable noise spectrum which is high for the low frequency range and which is low for the high frequency range. Conversely, if the high-range input audio signal is high such that the masking effect for the high-frequency range is high, the synthesis information is produced by the synthesis ratio which will give an allowable noise level which becomes high and low for the high and low frequency ranges, respectively. The information of the allowable noise spectrum, produced in this manner, is transmitted to the filter coefficient calculating unit 36 from which filter coefficients conforming to the allowable noise spectrum are outputted and transmitted to the noise filter 23. In this manner, the filter coefficients as filtering properties of the noise filter 23 are based on the allowable noise spectrum obtained by changing the synthesis ratio from band to band depending on the input signal level. It is now assumed that for a flat input audio signal level, the noise filter 23 is of filtering characteristics shown by a curve MR in FIGS. 10 to 13. If the input audio signal becomes a signal S1 having a slightly nigh level at a lower frequency, as shown in FIG. 10, the filtering characteristics are changes to those in which the high-range response and the low-range response are lowered and raised slightly from the curve MR, respectively, as shown by a curve MR1 in FIG. 10, by changing the synthesis ratio as mentioned above. On the other hand, if the input audio signal becomes a signal S2 having a high level at a lower frequency, as shown in FIG. 11, the filtering characteristics of the noise filter 23 are changed to those in which the high-range response and the low-range response are lowered and raised significantly from the curve MR, respectively, as shown by a curve MR2 in FIG. 10. Conversely, if the input audio signal becomes a signal S3 having a slightly high level at a higher frequency, as shown in FIG. 12, the filtering characteristics are changed to those in which the high-range response and the low-range response are raised and lowered slightly from the curve MR, respectively, as shown by a curve MR3 in FIG. 12. If the input audio signal becomes a signal S4 having a high level at a higher frequency, as shown in FIG. 13, the filtering characteristics of the noise filter 23 are changed to those in which the high-range response and the low-range response are raised and lowered significantly from the curve MR, respectively, as shown by a curve MR4 in FIG. 13. By changing the filtering characteristics s shown in FIGS. 10 to 13, the noise shaping may be achieved which is matched more closely to the aural sense of a human being. In other words, with the present embodiment, the filtering characteristics represented by the curve RC which is the equal loudness curve normalized with the critical bandwidth are used as the filtering characteristics of the noise filter 23, as long as the input audio signal level is low, by way of nose shaping. As the signal level becomes higher, the noise filter characteristics are rendered flatter to match the noise filter characteristics to the signal level of the input audio signal to render the quantization noise less outstanding by the input audio signal level. Besides, if the input signal level is low, the filtering characteristics as represented by the curve RC are rendered flatter by the noise filter 23 to conform to the input signal level for changing the noise shaping characteristics, such as masking characteristics, into conformity with the input signal characteristics. That is, the filtering characteristics as indicated by the curve RC which is the equal loudness curve normalized with the critical bandwidth are employed for the lower input signal level, while the filtering characteristics which take the masking effect into account is employed for the higher input signal level. As for the curve MR showing filtering characteristics for the flatter input audio signal level shown in FIGS. 10 to 13, it may be contemplated to increase the input signal level, that is to increase the allowable noise level, for the input signal level of not lower than 4 kHz, if the equal loudness curve RC shown in FIG. 9 is taken into account. However, since the region of the equal loudness curve RC not higher than 4 kHz exhibits acute changes despite the narrower bandwidth, the number of orders of the filter is increased if the noise filter 23 is designed for matching the region of the equal loudness curve not higher than 4 kHz to the curve RC which is the equal loudness curve normalized with the critical bandwidth. Since the effects matched to the number of the filter orders are not achieved in this manner, the flatter filtering characteristics are employed in the present embodiment for the range of not higher than 4 kHz as described above.
An apparatus and method for processing an input digital signal in which an input digital audio signal at an input terminal 11 is supplied via a one-block delay unit 17 to a difference unit 20, an output of which is processed by a noise-shaping circuit 21 and restored by a near-instantaneous compressor 26, a near-instantaneous expander 27 and an accumulator 28 so as to be fed back to the difference unit 20 to find a difference between a signal of a directly preceding sample and a signal of the current sample. The noise shaping circuit 21 modifies the spectrum of the quantization noise by taking aural characteristics, such as equal-loudness characteristics or masking characteristics, into account for diminishing the level of the quantization noise as perceived by the ear. The noise level as perceived may be reduced in a manner desirable for the sound quality without changing the existing format.
Briefly summarize the main idea's components and working principles as described in the context.
[ "This application is a division of Ser.", "No. 08/142,873 filed Oct. 28, 1993.", "BACKGROUND OF THE INVENTION This invention relates to a high efficiency encoding device and a noise spectrum modifying device and method for speech or audio signals.", "More particularly, it relates to a high efficiency encoding device and a noise spectrum modifying device and method of the sub-sampling encoding system, such as MUSE, in which the quantization noise spectrum is rendered aurally acceptable by reducing the noise level as perceived by the ear to improve the quality of the speech or audio signals for high definition telecasting.", "As a system for high efficiency encoding of digital audio signals there has hitherto been proposed a system consisting in the combination of differential encoding and near-instantaneous compression.", "According to the proposed system a difference between two neighboring samples of the digital audio signals is compressed on a block unit basis, by way of near-instantaneous compression, using range information as found based on a maximum value of the difference in a block consisting of a pre-set number of samples.", "There has also been disclosed in JP Patent KOKAI Publication No. 63-16718 (1988) a technique in which the difference is found based on a difference between signals of the current sample and signals of a directly previous sample restored by processing with near-instantaneous compression, near-instantaneous expansion and accumulation to correct the errors produced at the time of the range compression.", "Such high efficiency encoding system, consisting in the combination of the differential encoding and near-instantaneous compression and expansion (compansion) is employed for encoding audio signals processed with bandwidth compression by the multiple subsampling encoding system, such as MUSE, for telecasting or recording on a recording medium, such as a recording disc, of high definition television signals, such as so-called high-vision signals.", "FIG. 1 shows characteristics in the high-efficiency encoding by the above-described conventional combination of the differential encoding and near-instantaneous compansion.", "In FIG. 1, curves A and B represent an output signal level and a noise level, respectively.", "Thus it is seen that the S/N ratio is lowered towards higher frequencies at a rate of 6 dB/oct.", "The quantization noise shows a substantially flat spectrum.", "The status shown in FIG. 1 is not fully satisfactory as long as the aural sense of human being is concerned, although a minimum noise energy may thereby be achieved.", "Above all, the S/N ratio is lowered when the high-range signal is supplied as an input signal.", "OBJECT AND SUMMARY OF THE INVENTION In view of the above-described status of the art, it is an object of the present invention to provide a high efficiency encoding device, a noise spectrum modifying device and method whereby, when encoding audio signals by the combination of the differential encoding and near-instantaneous compansion, the quantization noise as perceived by the ear may be reduced to improve the sound quality without changing the existing format.", "For accomplishing the above object, the present invention provides a high efficiency encoding apparatus comprising difference signal outputting means having a local demodulating function, quantization means having a near-instantaneous compansion and noise-shaping means for modifying the spectrum of the quantization noise.", "It is preferred for the noise shaping characteristics of the noise shaping means to be substantially the equal-loudness characteristics normalized with the critical bandwidth.", "It is also preferred for the noise shaping characteristics to be substantially flat for a frequency region not higher than 4 kHz.", "It is similarly preferred for the noise shaping characteristics of the noise shaping means to be obtained by mixing the characteristics substantially similar to the equal-loudness characteristics normalized with the critical bandwidth and the masking threshold characteristics, while it is also preferred for the masking threshold characteristics to be mixed at a higher proportion with and increase in the input signal level.", "Thus the present invention consists of modifying the spectrum of the quantization noise so that the noise as heard by the ears becomes lower.", "To this end, error feedback may be employed.", "The equal-loudness characteristics and masking characteristics may be employed for reducing the noise as heard by the ears.", "The concept of the critical bands may be employed in converting the equal-loudness characteristics into characteristics of the noise spectrum.", "According to the present invention, the quantization noise as perceived by the ears may be reduced by taking into account the equal loudness characteristics and masking characteristics by the noise shaping means which modify the spectrum of the quantization noise.", "That is, the noise level as perceived by the ears may be reduced in a manner desirable for the sound quality without modifying existing formats, such as the speech format for high definition telecasting or recording on the recording medium by the so-called MUSE system or the decoders.", "With the high efficiency encoding apparatus according to the present invention, comprising difference signal outputting means having a local demodulating function, quantization means having a near-instantaneous compansion function and noise-shaping means for modifying the spectrum of the quantization noise, the quantization noise as perceived by the ears may be reduced by taking into account the equal-loudness characteristics and the masking characteristics by the noise shaping means which modifies the quantization noise spectrum.", "It should be noted that the characteristics of the noise filter provided in the noise shaping means are set on the basis of at least one of the characteristics based on the information of the equal-loudness characteristics and the masking characteristics as obtained from the information derived from the frequency analysis of the input audio signal and, if both of them are employed, a synthesis ratio between the characteristics based on the information of the equal-loudness characteristics and the masking characteristics as obtained from the information derived from the frequency analysis of the input audio signal is set based on the information which is changed depending on the input audio signal level.", "It becomes possible in this manner to reduce the noise as perceived by the ears to improve the dynamic range as far as the aural sense of the human being is concerned.", "Therefore, if the high efficiency encoding device for audio signals according to the present invention is applied to, for example, standardized digital audio equipment, it becomes possible to produce the playback sound having a higher dynamic range than that actually realized under the unified standard as long as the aural sense of the human being is concerned.", "For example, the dynamic range of the reproduced audio signal as perceived by the ears may be improved under maintenance of the existing unified standard, that is, under maintenance of compatibility without modifying the playback side arrangement.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing signal-to-noise characteristics of a conventional high efficiency encoding device for audio signals.", "FIG. 2 is a block diagram showing a processing device according to a first embodiment of the present invention.", "FIG. 3 is a graph showing noise-shaping characteristics for reducing the aurally perceived noise level.", "FIG. 4 shows typical examples of the relation between the center frequencies of the critical bands and the bandwidth.", "FIG. 5 is a graph showing the relation between the noise shaping characteristics of the embodiments of the present invention and the equal loudness curve as normalized with the bandwidth of the critical bands.", "FIG. 6 is a block diagram showing a processing device according to the second embodiment of the present invention in which the equal loudness characteristics and masking characteristics are taken into account.", "FIG. 7 is a graph showing masking characteristics for a sine wave input.", "FIG. 8 is a graph showing masking characteristics by plural spectral components.", "FIG. 9 is a graph showing equal loudness characteristics and comprehensive masking characteristics by plural spectral components.", "FIG. 10 is a graph showing a frequency response for low-range input signals having a slightly high signal level.", "FIG. 11 is a graph showing a frequency response for low-range input signals having a high signal level.", "FIG. 12 is a graph showing a frequency response for high-range input signals having a slightly high signal level.", "FIG. 13 is a graph showing a frequency response for high-range input signals having a high signal level.", "DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, a first embodiment according to the present invention will be explained in detail.", "In FIG. 2, a digital speech or audio signal, supplied to an input terminal 11, is transmitted to a subtractive node 12 and to a one-sample delay unit 13.", "A delay signal from the one-sample delay unit 13 is transmitted to the subtractive node 12 so that a difference signal between neighboring samples is outputted from the subtractive node 12.", "The difference signal is transmitted to a range detector 14 for sequentially detecting the signal levels in the course of a given block.", "The maximum level as detected during the one-block interval is used for determining the compression range of the difference signal for the block.", "The range signal from the range detector 14 is held for the one-block interval by a one-block holder 15 before being outputted at a range output terminal 16.", "The input signal at the input terminal 11 is also delayed by one block by a one-block delay unit 17 and thence supplied via a difference unit 20 to an annexed noise shaping circuit 21 for noise shaping, from which the noise-shaped signal is restored via a near-instantaneous compressor 26, a near-instantaneous expander 27 and an accumulator 28 and thence supplied to the difference unit 20 for difference taking.", "A delayed output of the one-block delay unit 17 is supplied to a fixed terminal a of a changeover switch 18, while an output signal of the near-instantaneous compressor 26 is transmitted to a fixed terminal b of the changeover switch 18.", "An output of the changeover switch 18 is issued at a difference signal output terminal 19.", "In the first embodiment of the present invention, there is annexed the noise shaping circuit 21 having a subtractive node 24 for finding a difference between an input to the near-instantaneous compressor 26 and an output of the near-instantaneous expander 27 for taking out only the quantization noise which is processed with a filter 23 consisting of a first-order linear coupled circuit before being fed back via an additive (subtractive) node 22.", "The transfer characteristics of the first-order linear coupled circuit constituting the filter 23 are generally represented as Σa n z -n .", "The noise-shaping characteristics for a typical set of coefficients of the first-order linear coupled circuit, which represent the equal-loudness characteristics normalized by the critical band width, are shown in FIG. 3, in which curves A and B denote the equal-loudness characteristic curve and the noise-shaping characteristic curve normalized with the critical band widths, respectively.", "That is, the equal-loudness characteristics A and the noise shaping characteristics B represent the subjective magnitude of sine wave signals at each frequency and the noise spectrum, respectively.", "Consequently, it becomes necessary to establish the relation of matching between the subjective magnitude of the sine wave signals and the subjective magnitude of the noise.", "This may be achieved by relying upon the concept of the critical band.", "That is, the noise shaping characteristics capable of affording the noise spectrum matched to the equal loudness characteristics may be obtained by calculating the pure energy of the noise in each critical band and coinciding the calculated energy with the equal loudness level of the sine waves at the center frequency of each critical band.", "Since the critical band width becomes broader for the higher frequency, it is unnecessary for the noise shaping characteristics to be increased as strongly as the equal loudness characteristics towards higher frequencies.", "FIGS. 3 and 4 illustrate typical characteristics and the typical numerical relation between the center frequencies and the bandwidth of the critical bands, respectively.", "In FIG. 5, in which the critical band numbers (Bark) are plotted on the abscissa, there are shown an equal loudness characteristic curve A normalized with the critical band widths and a noise shaping characteristic curve B according to the present invention.", "The noise shaping characteristic curve B according to the present invention is adjusted so as to be coincident with the equal loudness characteristic curve at the frequencies approximately equal to 4 kHz and higher.", "At the frequencies lower than 4 kHz, the noise shaping characteristics may be drawn closer to flatness for lowering the number of orders of the digital filter.", "Referring to the drawings, the second embodiment of the present invention will be explained.", "FIG. 6 shows, in a block diagram, a schematic arrangement of a second embodiment for reducing the quantization errors for audio signals.", "The device shown in FIG. 6 is a high efficiency encoding device including a noise shaping circuit which also takes the masking effects into account.", "The device shown in FIG. 6 is designed to feed back the quantization errors produced in the near-instantaneous compressor 26 to the input side of the near-instantaneous compressor 26 via, among other things, a noise filter 23, and comprises a level detection unit 34 for detecting the level of the input audio signal, a frequency analysis unit 31 for performing frequency analysis of the input audio signal from one critical band to another, an equal loudness curve generating unit 35 for generating the information conforming to the human auditory sense based on the so-called equal loudness curve shown in FIG. 5, and an allowable noise spectrum calculating unit 33 for changing the synthesis ratio between the output of the equal loudness curve generating unit 35 and the output of the masking characteristic processing unit 32 for realization of the optimum quantization noise spectrum by the output of the frequency analysis unit 31 depending on the output of the level detecting unit 34 for calculating the allowable noise spectrum based on the resulting synthesis information.", "The device shown in FIG. 6 is designed to set the filter characteristics of the noise filter 23 based on the output information of the allowable noise spectrum calculating unit 33.", "That is, in the present embodiment, a so-called error feedback circuit is made up of the subtractive node 24 for subtracting the input to the near-instantaneous compressor 26 from the output of the near-instantaneous expander 27 for producing a quantization error generated at the time of quantization at the quasi-instantaneous compressor 26, the noise filter 23 for filtering the output of the subtractive node 24 to output the filtered output, and an additive node (subtractive node) 22 for adding the output of the noise filter 23 to the input of the near-instantaneous compressor 26.", "The filter characteristics of the noise filter 23 are determined by calculating filter coefficients by a filter coefficient calculating unit 36 based on the information of the allowable noise spectrum information of the allowable spectrum calculating unit 33 as later explained and by transmitting the filter coefficient information to the noise filter 23.", "Thus the error feedback circuit performs the quantization error reducing operation (so-called noise shaping) based on the allowable noise spectrum, as later explained, and the output of the error feedback circuit is subsequently issued at an output terminal 19.", "The construction and the operation are otherwise the same as that of the first embodiment shown in FIG. 2 so that the corresponding parts are indicated by the same numerals and the corresponding description is omitted.", "Meanwhile, when the quantization error reducing operation (noise-shaping operation) is to be performed by the above-described error feedback circuit, the dynamic range of the audio signals as perceived by the human aural sense may be increased by a processing which takes the masking of the input signal spectrum into account.", "As the noise shaping taking the masking into account, there are a noise shaping conforming to the signal spectrum of the input audio signal having a more or less fixed pattern, that is a noise shaping which makes use of the allowable noise spectrum produced by taking the so-called masking of the input audio signal spectrum into account, and a noise shaping which makes use of the allowable noise spectrum which is adapted to changes in the spectrum of the input audio signals and which is obtained by taking the masking of the spectrum into account.", "By the masking is meant the phenomenon in which, owing to the aural feature of a human being, a signal becomes masked by another sound and becomes inaudible.", "Among the masking effects, there are a masking effect on signals on the time domain and a masking effect on signals on the frequency domain, that is a concurrent masking or a temporal masking.", "Due to the masking effects, any noise present in a masked region becomes inaudible.", "As for the concurrent masking effect as shown in FIG. 7, if the frequency response of a signal S at a given frequency is 0 dB, a masking effect acts in a region below a curve M (for approximately -25 dB or lower) by the signal S. Besides, if the input signal is segmented according to the critical bands to take advantage of the auditory sense characteristic of a human being and the noise shaping is performed by employing the allowable noise spectrum taking the above-mentioned masking into account for each critical band, the noise shaping which is more effective for the auditory sense characteristic of a human being may be achieved.", "It becomes possible in this manner to improve the dynamic range of the reproduced sound as perceived by the ears.", "Thus the frequency analysis unit 31 segments the input audio signals by the so-called critical bands by taking advantage of characteristics of the human auditory sense and performs frequency analysis for each of the critical bands.", "In segmenting the input audio signal by the critical bands, it is possible to translate the input audio signal into components on the frequency domain (FFT coefficients) by e.g. the fast Fourier transform (FFT) and to classify the amplitude terms Am of the FFT coefficients, m being 0 to 1024, into e.g. 25 bands or groups Gn, n indicating the band or group numbers and being 0 to 24, in accordance with the above-mentioned critical band widths which become broader towards higher frequencies for taking account of the characteristics of the human auditory sense.", "By way of the frequency analyses for each of the critical bands, a so-called Bark spectrum Bn or the spectrum of total sums, which may be found by finding the total sum of the amplitude terms Am (total sum of the peaks, mean values or energies) for the respective bands, may also be found in accordance with the equation (1): Bn=10 log 10 Cn(Pn)2 dB (1) In the equation (1), n=0 to 24, Cn is the number of elements that is the amplitude terms (number of points) in the n'th band, and Pn is the peak value for the respective bands.", "A typical Bark spectrum for the respective bands is shown in FIG. 8, in which the number of the critical bands is set to 12 (B1 to B12) for brevity.", "The frequency analysis unit 31 performs the division by the critical bandwidth and the frequency analysis from one critical band to another and transmits the output information to the masking characteristics calculating unit 32.", "The equal loudness curve generating unit 35 generates and outputs the information which is the equal loudness curve normalized with the critical bandwidth.", "The equal loudness curve represents aural characteristics of human being and is obtained by interconnecting the sound pressures of the sounds at the respective frequencies heard with the equal loudness as a pure sound of 1 kHz.", "It is also known as the equal loudness sensitivity curve.", "As shown by a curve RC of FIG. 9, representing the equal loudness curve, the hearing power of human being is strongest in the vicinity of 4 kHz, such that the sound of 4 kHz is heard with substantially an equal loudness as the 1 kHz sound even if the sound pressure is lower by e.g. 8 to 10 dB than the 1 kHz sound, while the sound of e.g. 10 kHz is less audible by about 20 dB than the 4 kHz sound.", "Consequently, the dynamic range of the reproduced sound as perceived by the ear may be improved by noise shaping the audio signals by the error feedback circuit based on the curve RC which is the equal loudness curve normalized with the critical bandwidth.", "That is, by performing the noise shaping using the allowable noise spectrum obtained by taking into account the curve RC which is the equal loudness curve normalized with the critical bandwidth, noise shaping more effective in view of the aural sense of human being may be realized to improve the dynamic range of the reproduced sound as heard by the listener.", "The information concerning the curve RC, which is the equal loudness curve normalized with the critical bandwidth as perceived by the ear, or a curve approximated to the curve RC, is outputted by the equal loudness curve generating unit 35 so as to be supplied to the allowable noise spectrum calculating unit 33.", "The allowable noise spectrum calculating unit 33 calculates the allowable noise spectrum based on the output information from the equal loudness curve generating unit 35 and the output information of the masking characteristics calculating unit 32.", "At this time, the Bark spectral components Bn for the respective critical bands produced by the frequency analysis unit 31 are convolved to take into account the effects of the neighboring bands in accordance with equation (2) Sn=Hn*Bn (2) wherein Hn denotes convolution coefficients, for calculating the convolved Bark spectrum Sn for the respective bands.", "By the convolution, the sum total of dotted-line portions in FIG. 8 is found.", "Then, using the convolved Bark spectrum Sn and the S/N value On as required, n being equal to 0 to 24, the masking threshold Tn resulting from convolution is calculated by equations (3) and (4): On=K-Kxn (3) Tn=Sn-On (4) For example, it can be set that K=1 for N=38, in which case the deterioration in the sound quality is diminished.", "That is, as shown in FIG. 10, the level lower than the levels of the convolved masking threshold Tn is masked.", "The convolved masking threshold Tn is subsequently deconvolved by equation (5): TFn=Tn-Dn (5) to calculate the allowable noise level (allowable noise spectrum) TFn.", "In effect, the dc gain Dn of the convolution by the coefficient Hn is subtracted from Tn.", "The allowable noise spectrum calculating unit 33 calculates the allowable noise spectrum based on the information obtained by combining the output information of the masking characteristic calculating unit 32 with the output information of the equal loudness curve generating unit 35.", "Meanwhile, it may occur that the allowable noise level with the allowable noise spectrum based on the curve RC which is the equal loudness curve normalized by the critical bandwidth becomes lower than the allowable noise level by the masking effects which depends on the input signal level.", "That is, with the higher input audio signal level, it may occur that the level of the allowable noise level based on the equal loudness curve is simultaneously masked by the allowable noise level by the masking effect which depends on the input audio signal.", "Thus, with the present embodiment, the input audio signal level is detected by the level detecting unit 34 and the synthesis ratio of the output information of the equal loudness curve generating unit 35 and the output information of the masking characteristic calculating unit 32 is changed depending on the detected output level.", "It is noted that the synthesis of the output information of the equal loudness curve generating unit 35 and the output information of the masking characteristic calculating unit 32 is carried out from band to band.", "In such case, level detection by the level detection unit 34 is also made from band to band so that the synthesis ratio is changed from band to band depending on the band-based detected output level.", "That is, if the low-range input audio signal is high such that the masking effect for the low-frequency range is high, the synthesis ratio employed for producing the synthesis information for finding the allowable noise spectrum by the allowable noise spectrum calculating unit 33 is of such a value as to give an allowable noise spectrum which is high for the low frequency range and which is low for the high frequency range.", "Conversely, if the high-range input audio signal is high such that the masking effect for the high-frequency range is high, the synthesis information is produced by the synthesis ratio which will give an allowable noise level which becomes high and low for the high and low frequency ranges, respectively.", "The information of the allowable noise spectrum, produced in this manner, is transmitted to the filter coefficient calculating unit 36 from which filter coefficients conforming to the allowable noise spectrum are outputted and transmitted to the noise filter 23.", "In this manner, the filter coefficients as filtering properties of the noise filter 23 are based on the allowable noise spectrum obtained by changing the synthesis ratio from band to band depending on the input signal level.", "It is now assumed that for a flat input audio signal level, the noise filter 23 is of filtering characteristics shown by a curve MR in FIGS. 10 to 13.", "If the input audio signal becomes a signal S1 having a slightly nigh level at a lower frequency, as shown in FIG. 10, the filtering characteristics are changes to those in which the high-range response and the low-range response are lowered and raised slightly from the curve MR, respectively, as shown by a curve MR1 in FIG. 10, by changing the synthesis ratio as mentioned above.", "On the other hand, if the input audio signal becomes a signal S2 having a high level at a lower frequency, as shown in FIG. 11, the filtering characteristics of the noise filter 23 are changed to those in which the high-range response and the low-range response are lowered and raised significantly from the curve MR, respectively, as shown by a curve MR2 in FIG. 10.", "Conversely, if the input audio signal becomes a signal S3 having a slightly high level at a higher frequency, as shown in FIG. 12, the filtering characteristics are changed to those in which the high-range response and the low-range response are raised and lowered slightly from the curve MR, respectively, as shown by a curve MR3 in FIG. 12.", "If the input audio signal becomes a signal S4 having a high level at a higher frequency, as shown in FIG. 13, the filtering characteristics of the noise filter 23 are changed to those in which the high-range response and the low-range response are raised and lowered significantly from the curve MR, respectively, as shown by a curve MR4 in FIG. 13.", "By changing the filtering characteristics s shown in FIGS. 10 to 13, the noise shaping may be achieved which is matched more closely to the aural sense of a human being.", "In other words, with the present embodiment, the filtering characteristics represented by the curve RC which is the equal loudness curve normalized with the critical bandwidth are used as the filtering characteristics of the noise filter 23, as long as the input audio signal level is low, by way of nose shaping.", "As the signal level becomes higher, the noise filter characteristics are rendered flatter to match the noise filter characteristics to the signal level of the input audio signal to render the quantization noise less outstanding by the input audio signal level.", "Besides, if the input signal level is low, the filtering characteristics as represented by the curve RC are rendered flatter by the noise filter 23 to conform to the input signal level for changing the noise shaping characteristics, such as masking characteristics, into conformity with the input signal characteristics.", "That is, the filtering characteristics as indicated by the curve RC which is the equal loudness curve normalized with the critical bandwidth are employed for the lower input signal level, while the filtering characteristics which take the masking effect into account is employed for the higher input signal level.", "As for the curve MR showing filtering characteristics for the flatter input audio signal level shown in FIGS. 10 to 13, it may be contemplated to increase the input signal level, that is to increase the allowable noise level, for the input signal level of not lower than 4 kHz, if the equal loudness curve RC shown in FIG. 9 is taken into account.", "However, since the region of the equal loudness curve RC not higher than 4 kHz exhibits acute changes despite the narrower bandwidth, the number of orders of the filter is increased if the noise filter 23 is designed for matching the region of the equal loudness curve not higher than 4 kHz to the curve RC which is the equal loudness curve normalized with the critical bandwidth.", "Since the effects matched to the number of the filter orders are not achieved in this manner, the flatter filtering characteristics are employed in the present embodiment for the range of not higher than 4 kHz as described above." ]
BACKGROUND OF THE INVENTION The present invention relates a light barrier system with a radiation source and a radiation sensor, acted on by the radiation of said source and having at least two sensor elements, and including means for polarizing the radiation differently in two branches, and different polarization radiation filters in front of the two sensor elements for detecting the intensity of radiation in the two respective branches, and wherein the two sensor elements are connected in a gating circuit which emits a signal on different irradiation intensities being received by the two sensor elements. Light barriers are known, e.g., from DE No. 1,934,321 or DE No. 2,014,107 and serve preferably to protect against intrusion. As soon as radiation, (which is preferably in the infrared or visible spectral region), emitted by a radiation source and directed towards a radiation sensor, is interrupted, e.g., by the body of an intruder or by being covered during an attempt at sabotage, a gating circuit releases an alarm signal. The polarization of the radiation emitted by the radiation source and the arrangement of an equivalent polarizing filter in front of one of the sensor elements, (such that the other sensor element receives radiation which is not or is differently polarized), results in the gating circuit not emitting an output signal when some other radiation, e.g., solar radiation or diffused light, impinges upon the radiation sensor, the polarization of which is different from that of the light barrier radiation. Alternatively the said other radiation may not be polarized, in which event both sensor elements are acted on equally. Light barriers of this kind, if properly designed, may also be utilized for outside application during daylight hours. For such use the discrimination against interference can be improved by employing alternating radiation of a defined frequency and by tuning the frequency of the gating circuit to synchronize with that of the radiation source as is known in the art. To provide synchronization, the radiation source is typically connected with the radiation sensor or the gating circuit, with the radiation source and radiation sensors located proximate to each other and a reflector is located at a distance from the source and sensors to reflect radiation from the source back to the sensors. However, a reflector is very sensitive to soiling and misalignment, so that the range of such a light barrier, i.e., the safely controllable length of the distance monitored, is therefore rather limited. Light barriers for outside applications with a larger range, extending from about 10 meters to more than 100 meters, however, are influenced by the weather since fog and rain drops cause radiation scatter, so that when weather conditions are unfavorable, a noticeable weakening of the radiation received will occur, particularly when the path of the radiation between radiation source and radiation sensor is large. In order to prevent the release of a faulty alarm signal in such a case, the sensitivity of the gating circuit must be reduced correspondingly. Moreover in case of a weather-conditioned enlargement of the monitoring beam resulting from radiation scatter, the weakening of the radiation becomes smaller as a result of an object, e.g., an intruder, so that at unfavorable weather conditions, an intruder can no longer be recognized since sufficient scattered radiation still impinges upon the sensor. SUMMARY OF THE INVENTION An object of the present invention is to overcome the aforeindicated shortcomings of the prior art, and in particular, to provide a light barrier which even when used outdoors and in the presence of external light as well as scattered radiation due to weather conditions, is able to detect accurately at extended ranges, with improved protection from interference of an object to be detected, e.g., an intruder. In accordance with the present invention, the aforesaid objectives are achieved by utilizing two radiation branches which are spatially offset relative to each other and having different polarizations which are independent of each other, and by directing the radiation from the two respective radiation branches with different polarizations towards separate respective sensor elements. Different and independent polarization in the two radiation branches may be obtained by means of suitable polarization filters in front of the radiation source which are linearly polarized, perpendicularly or orthogonally relative to each other. Advantageously, the polarization planes may be selected inclined by an angle of 45° relative to the horizontal or vertical so that elliptically polarized external light with vertical and horizontal main axes, e.g., sunlight, is rendered ineffective because at an inclination of 45° such light acts equally on both sensor elements. Likewise, a circular polarization with opposite senses of rotation may be employed advantageously. In such a case, a corresponding polarization filter combination in front of the radiation sensor is to be provided in each case which, possibly in collaboration with suitable optical elements, guides the polarized radiation from one radiation branch to one sensor element and the radiation from the other radiation branch to the other sensor element. By making use of such a polarization filter combination ahead of the radiation sensor it becomes possible to separate radiation with different polarizations from each other even if both radiation branches overlap in part, whereby an even larger range may be attained. The invention as well as suitable and advantageous further refinements thereof are explained in detail with reference to the examples of embodiments represented in the figures. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a first embodiment of a light barrier according to the invention, FIG. 2 shows a second form of embodiment of a light barrier according to the invention, FIG. 3 shows polarization filters with linear polarization, FIG. 4 shows polarization filters with linear polarization, the polarization planes thereof being inclined by an angle of 45° relative to the horizontal plane, FIG. 5 shows polarization filters with circular polarization in opposite directions, and FIG. 6 is an electrical diagram of a gating circuit. DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the light barrier system represented in FIG. 1, a radiation source 1, e.g., a commercially available light-emitting diode (LED) emits radiation, e.g., infrared or luminous radiation, preferably infrared with approximately 0.9 μm wavelength, which by means of a lens 2 is rendered into a beam in the direction of the monitored section 3. Following the lens 2 is arranged a polarization filter 4 which by means of a preferably vertical dividing plane is divided into two halves with different polarizations. The polarizations in the two halves are mutually exclusive from each other, i.e., the radiation of one polarization type is extinguished by the other half of the filter, and vice versa. By means of this divided polarization filter, the radiation in the monitored section 3 is divided into two radiation branches 3 1 and 3 2 with correspondingly different polarizations. In the example shown in which a simple focusing lens 2 is employed, the two radiation beams overlap only partly and are arranged side-by-side, preferably side-by-side horizontally. The radiation from the two radiation branches 3 1 and 3 2 advances via a further polarization filter 5, divided into two halves and corresponding to the type of polarization of the first filter 4, and two half-lenses 6 1 and 6 2 which are separated by a diaphragm 7 and have the same plane of division as the polarization filter 5, towards sensor elements 8 1 and 8 2 , respectively, of a dual radiation sensor 8 whose spectral sensitivity corresponds to the radiation source 1, where it is focused. Even though the two radiation branches 3 1 and 3 2 intersect or overlap to some extent in the center region, the radiation sensor element 8 1 receives exclusively radiation from the branch 3 1 which was passed through the polarization filter part 4 1 because the share which was delivered by the other half 4 2 is absorbed by the polarization filter part 5 1 . Similarly, the sensor element 8 2 receives exclusively radiation from the filter part 4 2 of the radiation branch 3 2 . In this manner a clean separation of the two radiation branches is obtained, even if only relatively simple and low-cost optical elements are employed, so that in an especially simple manner an especially large useful range of the light barrier can be attained without the interfering effect of the unavoidable divergence of the radiation branches. It is evident, however, that in place of simple focusing lenses, more structurally complex lens systems with better precision may be employed, by which the two radiation branches can be maintained with even better separation from each other, whereby the range of the light barrier and its usability under unfavorable weather conditions may be further improved. The two sensor elements 8 1 and 8 2 are connected with a gating circuit 9 which is designed, e.g., in form of a differential circuit and delivers a signal corresponding to the difference in radiation received by the two elements. Through non-polarized or differently polarized external radiation, e.g., sunlight or daylight, both sensor elements are acted on by radiation in an equal manner and the gating circuit 9 does not deliver a signal, i.e., external radiation of this kind is automatically eliminated. If radiation-scattering fog appears within the monitored section 3, the irradiation of both sensor elements 8 1 , 8 2 is likewise influenced in the same manner, so that again no difference occurs and the differential circuit 9 does not transmit a signal. Thus, the device can be operated even under unfavorable conditions, i.e., in the presence of external radiation, in fog or rain, over a very large range or length of distance monitored, with undiminished or even improved sensitivity, without the light barrier becoming insensitive or delivering a false signal. However, a true intruder will cross the two radiation branches 3 1 , 3 2 , spatially offset relative to each other, one after the other and thereby generate a difference signal, i.e., the intruder will trigger an alarm signal in any case with considerable safety. The safety of detection and the selectivity pertaining to an intruder can thereby be further improved in that the gating circuit is rendered such that the signals delivered by the two sensor elements 8 1 and 8 2 must occur with a defined time differential relative to each other, e.g., within a predetermined time window and with a defined intensity, or with other suitable criteria, in order to be able to trigger an alarm. By means of a suitably designed circuit further information may be obtained from the signals e.g., regarding the size and the speed of the detected object. Turning now to the embodiment represented in FIG. 2, whereby identical elements are provided with the same reference numerals as for the aforedescribed light barrier in FIG. 1, a first polarization (transmitter-side) filter 10, divided into halves, is arranged between the radiation source 1 and the lens 2 and an additional polarization (receiver-side) filter 11 between the half-lenses 6 1 , 6 2 and the radiation sensor 8. Instead, the polarization filters may also be applied directly to the surfaces, i.e., the front side or the back side, of the lens 2 and, respectively, of the half-lenses 6 1 and 6 2 . It is also possible to fashion the lens 2 from differently polarized components of polarizing material or to constitute this lens with zones of different polarization, whereby in each case the receiver-side lenses are constructed and arranged analogously to the transmitter-side lenses. Further variants are possible, too, within the framework of the invention. In place of arranging the radiation branches horizontally side-by-side, they may also be provided in a different manner. For example, the branches may be constituted as a center portion and a ring surrounding same concentrically while the radiation sensor is constituted correspondingly by a radiation-sensitive circular center zone and a second radiation-sensitive ring shaped zone surrounding the circular center zone. Accordingly, orientation thereof need no longer be paid attention to during assembly. FIG. 3 shows a polarization filter 4 or 5 and, respectively, 10 or 11 which through a vertical separating line 12 is sub-divided into two halves 13 and 14 with different polarizations. The polarization is linear in both halves, namely, in one half, 13, in the vertical and in the other half, 14, orthogonally thereto, in the horizontal direction. Thus, the two polarizations are mutually exclusive of each other, i.e., radiations polarized in this manner extinguish each other mutually. In case of the polarization filter represented in FIG. 4, linear polarization is likewise provided for. However, the two polarization directions in the halves 13 and 14 are inclined by approximately 45° relative to the horizontal or vertical. Since natural external radiations, e.g., sun radiation or sky light, are almost always predominantly vertically or horizontally polarized, if at all, their influence on the two sensor elements sensitized only for 45°-polarized radiation is equal and is eliminated by the gating circuit. In the embodiment of a polarization filter shown in FIG. 5, the two halves 13 and 14 are not rendered with linear, but are instead rendered with circular polarization. The two halves have opposite directions of rotation, i.e., the part 13 is rendered circularly polarizing counterclockwise and the part 14 clockwise. Accordingly, too, external radiations can be largely eliminated or rendered ineffective. As already mentioned, the separating line 12 of the two halves 13 and 14 of the polarization filters 4 and 5 need not necessarily extend vertically. However, the division should ensure that radiation branches are formed which are passed through by an intruder one after the other with a defined measurable time difference. FIG. 6 illustrates an example of a suitable gating circuit whereby the two sensor elements 8 1 and 8 2 are rendered in form of phototransistors --Ph-- which with associated resistors are connected in an emitter follower circuit and by way of respective preamplifiers 15 and 16, respectively deliver their output signal to respective sample-and-hold circuits 17 and 18. Inasmuch as the radiation source, for reasons of protection from interference, is operated preferably as a pulse radiator with a defined pulse frequency and the preamplifiers are designed to be co respondingly frequency-selective, the two sample-and-hold circuits 17 and 18 store the pulse maxima for a short time and deliver them to a differential circuit 19. On the other hand, they deliver a signal to a monitoring circuit 20 when input pulses do not appear or their magnitude drops below a given threshold, thus indicating interference or a sabotage attempt. The positive input of the differential circuit 19 is actuated by one sensor element 8 1 , and the negative input by the other sensor element 8 2 . A positive or negative signal will appear at the output of the differential circuit 19, depending on which sensor element was subjected to radiation. In the event that the two radiation branches are passed through in sequence by an object, a positive pulse and a negative pulse will sequentially appear within a short time interval. The output signals of the differential circuit 19 are delivered to both positive and negative threshold value detectors 21, 22, which transmit the signals to two crosswise connected OR-gates, 23, 24 if their intensity exceeds the predefined threshold values. In case a first positive (or negative) pulse appears, the OR-gates 23 and 24 transmit a start pulse to the start input of a counter and time window comparator 25 and the second negative (or positive) pulse to the stop input of the said counter 25. The counter 25 delivers a signal to an alarm signal transmitter 26 if the second or stop pulse appears within a predefined time window, i.e., if the second pulse arrives after a defined minimum time period but before a predefined maximum time period. The minimum time period may be chosen to be zero, but a finite non-zero minimum time period offers increased safety. After the predefined maximum time period has lapsed, the stop input is blocked and the counter is automatically reset so that the circuit is again ready to operate. It is evident that other circuits with analogous and equivalent functions may be employed in place of the circuit described. While specific embodiments have been shown and described, it should be understood that numerous variations and modifications may be effected without departing from the true spirit and scope of the invention, which is defined only by the appended claims.
In a light barrier, especially for outside application and long distances monitored, insensitivity to interfering light and scattering through fumes or fog and an increased range and sensitivity to objects passing through the light barrier are achieved by subdividing radiation from a source into two radiation branches which are offset relative to each other and differently polarized, e.g., by means of a polarization filter divided into two parts, with different linear or oppositely circular polarization of the filter part surfaces. By means of an analogously subdivided polarization filter, the radiation of each of the two radiation branches is focused on a different individual sensor element. The two sensor elements are connected in a differential circuit which triggers an alarm signal in response to signals arriving from both radiation branches in short succession but does not trigger an alarm signal if both sensor elements are equally irradiated.
Provide a concise summary of the essential information conveyed in the given context.
[ "BACKGROUND OF THE INVENTION The present invention relates a light barrier system with a radiation source and a radiation sensor, acted on by the radiation of said source and having at least two sensor elements, and including means for polarizing the radiation differently in two branches, and different polarization radiation filters in front of the two sensor elements for detecting the intensity of radiation in the two respective branches, and wherein the two sensor elements are connected in a gating circuit which emits a signal on different irradiation intensities being received by the two sensor elements.", "Light barriers are known, e.g., from DE No. 1,934,321 or DE No. 2,014,107 and serve preferably to protect against intrusion.", "As soon as radiation, (which is preferably in the infrared or visible spectral region), emitted by a radiation source and directed towards a radiation sensor, is interrupted, e.g., by the body of an intruder or by being covered during an attempt at sabotage, a gating circuit releases an alarm signal.", "The polarization of the radiation emitted by the radiation source and the arrangement of an equivalent polarizing filter in front of one of the sensor elements, (such that the other sensor element receives radiation which is not or is differently polarized), results in the gating circuit not emitting an output signal when some other radiation, e.g., solar radiation or diffused light, impinges upon the radiation sensor, the polarization of which is different from that of the light barrier radiation.", "Alternatively the said other radiation may not be polarized, in which event both sensor elements are acted on equally.", "Light barriers of this kind, if properly designed, may also be utilized for outside application during daylight hours.", "For such use the discrimination against interference can be improved by employing alternating radiation of a defined frequency and by tuning the frequency of the gating circuit to synchronize with that of the radiation source as is known in the art.", "To provide synchronization, the radiation source is typically connected with the radiation sensor or the gating circuit, with the radiation source and radiation sensors located proximate to each other and a reflector is located at a distance from the source and sensors to reflect radiation from the source back to the sensors.", "However, a reflector is very sensitive to soiling and misalignment, so that the range of such a light barrier, i.e., the safely controllable length of the distance monitored, is therefore rather limited.", "Light barriers for outside applications with a larger range, extending from about 10 meters to more than 100 meters, however, are influenced by the weather since fog and rain drops cause radiation scatter, so that when weather conditions are unfavorable, a noticeable weakening of the radiation received will occur, particularly when the path of the radiation between radiation source and radiation sensor is large.", "In order to prevent the release of a faulty alarm signal in such a case, the sensitivity of the gating circuit must be reduced correspondingly.", "Moreover in case of a weather-conditioned enlargement of the monitoring beam resulting from radiation scatter, the weakening of the radiation becomes smaller as a result of an object, e.g., an intruder, so that at unfavorable weather conditions, an intruder can no longer be recognized since sufficient scattered radiation still impinges upon the sensor.", "SUMMARY OF THE INVENTION An object of the present invention is to overcome the aforeindicated shortcomings of the prior art, and in particular, to provide a light barrier which even when used outdoors and in the presence of external light as well as scattered radiation due to weather conditions, is able to detect accurately at extended ranges, with improved protection from interference of an object to be detected, e.g., an intruder.", "In accordance with the present invention, the aforesaid objectives are achieved by utilizing two radiation branches which are spatially offset relative to each other and having different polarizations which are independent of each other, and by directing the radiation from the two respective radiation branches with different polarizations towards separate respective sensor elements.", "Different and independent polarization in the two radiation branches may be obtained by means of suitable polarization filters in front of the radiation source which are linearly polarized, perpendicularly or orthogonally relative to each other.", "Advantageously, the polarization planes may be selected inclined by an angle of 45° relative to the horizontal or vertical so that elliptically polarized external light with vertical and horizontal main axes, e.g., sunlight, is rendered ineffective because at an inclination of 45° such light acts equally on both sensor elements.", "Likewise, a circular polarization with opposite senses of rotation may be employed advantageously.", "In such a case, a corresponding polarization filter combination in front of the radiation sensor is to be provided in each case which, possibly in collaboration with suitable optical elements, guides the polarized radiation from one radiation branch to one sensor element and the radiation from the other radiation branch to the other sensor element.", "By making use of such a polarization filter combination ahead of the radiation sensor it becomes possible to separate radiation with different polarizations from each other even if both radiation branches overlap in part, whereby an even larger range may be attained.", "The invention as well as suitable and advantageous further refinements thereof are explained in detail with reference to the examples of embodiments represented in the figures.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a first embodiment of a light barrier according to the invention, FIG. 2 shows a second form of embodiment of a light barrier according to the invention, FIG. 3 shows polarization filters with linear polarization, FIG. 4 shows polarization filters with linear polarization, the polarization planes thereof being inclined by an angle of 45° relative to the horizontal plane, FIG. 5 shows polarization filters with circular polarization in opposite directions, and FIG. 6 is an electrical diagram of a gating circuit.", "DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the light barrier system represented in FIG. 1, a radiation source 1, e.g., a commercially available light-emitting diode (LED) emits radiation, e.g., infrared or luminous radiation, preferably infrared with approximately 0.9 μm wavelength, which by means of a lens 2 is rendered into a beam in the direction of the monitored section 3.", "Following the lens 2 is arranged a polarization filter 4 which by means of a preferably vertical dividing plane is divided into two halves with different polarizations.", "The polarizations in the two halves are mutually exclusive from each other, i.e., the radiation of one polarization type is extinguished by the other half of the filter, and vice versa.", "By means of this divided polarization filter, the radiation in the monitored section 3 is divided into two radiation branches 3 1 and 3 2 with correspondingly different polarizations.", "In the example shown in which a simple focusing lens 2 is employed, the two radiation beams overlap only partly and are arranged side-by-side, preferably side-by-side horizontally.", "The radiation from the two radiation branches 3 1 and 3 2 advances via a further polarization filter 5, divided into two halves and corresponding to the type of polarization of the first filter 4, and two half-lenses 6 1 and 6 2 which are separated by a diaphragm 7 and have the same plane of division as the polarization filter 5, towards sensor elements 8 1 and 8 2 , respectively, of a dual radiation sensor 8 whose spectral sensitivity corresponds to the radiation source 1, where it is focused.", "Even though the two radiation branches 3 1 and 3 2 intersect or overlap to some extent in the center region, the radiation sensor element 8 1 receives exclusively radiation from the branch 3 1 which was passed through the polarization filter part 4 1 because the share which was delivered by the other half 4 2 is absorbed by the polarization filter part 5 1 .", "Similarly, the sensor element 8 2 receives exclusively radiation from the filter part 4 2 of the radiation branch 3 2 .", "In this manner a clean separation of the two radiation branches is obtained, even if only relatively simple and low-cost optical elements are employed, so that in an especially simple manner an especially large useful range of the light barrier can be attained without the interfering effect of the unavoidable divergence of the radiation branches.", "It is evident, however, that in place of simple focusing lenses, more structurally complex lens systems with better precision may be employed, by which the two radiation branches can be maintained with even better separation from each other, whereby the range of the light barrier and its usability under unfavorable weather conditions may be further improved.", "The two sensor elements 8 1 and 8 2 are connected with a gating circuit 9 which is designed, e.g., in form of a differential circuit and delivers a signal corresponding to the difference in radiation received by the two elements.", "Through non-polarized or differently polarized external radiation, e.g., sunlight or daylight, both sensor elements are acted on by radiation in an equal manner and the gating circuit 9 does not deliver a signal, i.e., external radiation of this kind is automatically eliminated.", "If radiation-scattering fog appears within the monitored section 3, the irradiation of both sensor elements 8 1 , 8 2 is likewise influenced in the same manner, so that again no difference occurs and the differential circuit 9 does not transmit a signal.", "Thus, the device can be operated even under unfavorable conditions, i.e., in the presence of external radiation, in fog or rain, over a very large range or length of distance monitored, with undiminished or even improved sensitivity, without the light barrier becoming insensitive or delivering a false signal.", "However, a true intruder will cross the two radiation branches 3 1 , 3 2 , spatially offset relative to each other, one after the other and thereby generate a difference signal, i.e., the intruder will trigger an alarm signal in any case with considerable safety.", "The safety of detection and the selectivity pertaining to an intruder can thereby be further improved in that the gating circuit is rendered such that the signals delivered by the two sensor elements 8 1 and 8 2 must occur with a defined time differential relative to each other, e.g., within a predetermined time window and with a defined intensity, or with other suitable criteria, in order to be able to trigger an alarm.", "By means of a suitably designed circuit further information may be obtained from the signals e.g., regarding the size and the speed of the detected object.", "Turning now to the embodiment represented in FIG. 2, whereby identical elements are provided with the same reference numerals as for the aforedescribed light barrier in FIG. 1, a first polarization (transmitter-side) filter 10, divided into halves, is arranged between the radiation source 1 and the lens 2 and an additional polarization (receiver-side) filter 11 between the half-lenses 6 1 , 6 2 and the radiation sensor 8.", "Instead, the polarization filters may also be applied directly to the surfaces, i.e., the front side or the back side, of the lens 2 and, respectively, of the half-lenses 6 1 and 6 2 .", "It is also possible to fashion the lens 2 from differently polarized components of polarizing material or to constitute this lens with zones of different polarization, whereby in each case the receiver-side lenses are constructed and arranged analogously to the transmitter-side lenses.", "Further variants are possible, too, within the framework of the invention.", "In place of arranging the radiation branches horizontally side-by-side, they may also be provided in a different manner.", "For example, the branches may be constituted as a center portion and a ring surrounding same concentrically while the radiation sensor is constituted correspondingly by a radiation-sensitive circular center zone and a second radiation-sensitive ring shaped zone surrounding the circular center zone.", "Accordingly, orientation thereof need no longer be paid attention to during assembly.", "FIG. 3 shows a polarization filter 4 or 5 and, respectively, 10 or 11 which through a vertical separating line 12 is sub-divided into two halves 13 and 14 with different polarizations.", "The polarization is linear in both halves, namely, in one half, 13, in the vertical and in the other half, 14, orthogonally thereto, in the horizontal direction.", "Thus, the two polarizations are mutually exclusive of each other, i.e., radiations polarized in this manner extinguish each other mutually.", "In case of the polarization filter represented in FIG. 4, linear polarization is likewise provided for.", "However, the two polarization directions in the halves 13 and 14 are inclined by approximately 45° relative to the horizontal or vertical.", "Since natural external radiations, e.g., sun radiation or sky light, are almost always predominantly vertically or horizontally polarized, if at all, their influence on the two sensor elements sensitized only for 45°-polarized radiation is equal and is eliminated by the gating circuit.", "In the embodiment of a polarization filter shown in FIG. 5, the two halves 13 and 14 are not rendered with linear, but are instead rendered with circular polarization.", "The two halves have opposite directions of rotation, i.e., the part 13 is rendered circularly polarizing counterclockwise and the part 14 clockwise.", "Accordingly, too, external radiations can be largely eliminated or rendered ineffective.", "As already mentioned, the separating line 12 of the two halves 13 and 14 of the polarization filters 4 and 5 need not necessarily extend vertically.", "However, the division should ensure that radiation branches are formed which are passed through by an intruder one after the other with a defined measurable time difference.", "FIG. 6 illustrates an example of a suitable gating circuit whereby the two sensor elements 8 1 and 8 2 are rendered in form of phototransistors --Ph-- which with associated resistors are connected in an emitter follower circuit and by way of respective preamplifiers 15 and 16, respectively deliver their output signal to respective sample-and-hold circuits 17 and 18.", "Inasmuch as the radiation source, for reasons of protection from interference, is operated preferably as a pulse radiator with a defined pulse frequency and the preamplifiers are designed to be co respondingly frequency-selective, the two sample-and-hold circuits 17 and 18 store the pulse maxima for a short time and deliver them to a differential circuit 19.", "On the other hand, they deliver a signal to a monitoring circuit 20 when input pulses do not appear or their magnitude drops below a given threshold, thus indicating interference or a sabotage attempt.", "The positive input of the differential circuit 19 is actuated by one sensor element 8 1 , and the negative input by the other sensor element 8 2 .", "A positive or negative signal will appear at the output of the differential circuit 19, depending on which sensor element was subjected to radiation.", "In the event that the two radiation branches are passed through in sequence by an object, a positive pulse and a negative pulse will sequentially appear within a short time interval.", "The output signals of the differential circuit 19 are delivered to both positive and negative threshold value detectors 21, 22, which transmit the signals to two crosswise connected OR-gates, 23, 24 if their intensity exceeds the predefined threshold values.", "In case a first positive (or negative) pulse appears, the OR-gates 23 and 24 transmit a start pulse to the start input of a counter and time window comparator 25 and the second negative (or positive) pulse to the stop input of the said counter 25.", "The counter 25 delivers a signal to an alarm signal transmitter 26 if the second or stop pulse appears within a predefined time window, i.e., if the second pulse arrives after a defined minimum time period but before a predefined maximum time period.", "The minimum time period may be chosen to be zero, but a finite non-zero minimum time period offers increased safety.", "After the predefined maximum time period has lapsed, the stop input is blocked and the counter is automatically reset so that the circuit is again ready to operate.", "It is evident that other circuits with analogous and equivalent functions may be employed in place of the circuit described.", "While specific embodiments have been shown and described, it should be understood that numerous variations and modifications may be effected without departing from the true spirit and scope of the invention, which is defined only by the appended claims." ]
FIELD OF THE INVENTION The present invention relates to digital electronic circuits, and more particularly to personal computer PCI-bus systems. DESCRIPTION OF THE PRIOR ART The peripheral component interface (PCI) bus has become the interface bus of choice for high-speed devices because it is well-equipped to handle newer, more demanding applications with its 32-bit data path, 33 MHz clock speed and a maximum data transfer rate of 132 MB/sec. However, PCI loading constraints limit the number of devices that can be supported directly on a system motherboard or through expansion slots, so PCI-to-PCI bridge chips have been developed by a number of major suppliers to increase the number of available system expansion slots. Embedding a bridge in a semiconductor device that also supplies other functionality provides a higher degree of integration and enables the creation of multi-function, multimedia expansion cards, where a single add-in card could support audio, graphics acceleration and video conferencing. The PCI bus is typically isolated from the CPU local bus by a PCI controller, a so-called "Northbridge". The CPU can thereby write data to PCI peripherals and go on to its next operation rather than waiting for the transfer to complete. The PCI controller stores the data in its buffer, and sends it out later at the most efficient rate. The PCI-bus supports intelligent-device bus mastering, so other masters can take control of the bus and do their jobs independent of the CPU. The CPU can run in parallel with the bus master peripheral because of the buffered design. The number of PCI peripheral devices that can be supported by a single PCI-bus is based on the electrical loading constraints defined in the industry-standard "PCI 2.1 Specification". A compliant PCI-bus is capable of supporting a total of ten loads, and two loads are consumed by the basic PCI chipset associated with the CPU. PC-device controllers that are built into the motherboard present only a single load. A single PCI-bus can therefore only support four expansion slots without violating the specification's loading constraints, e.g., one PCI device per expansion slot. High-end system designers have recently begun to build systems using PCI-to-PCI bridges to provide more expansion slots on the motherboard. The PCI bus specifications provide for an automatic configuration of any adapter or peripheral plugged into the bus to eliminate conflicts between boards in the system and the need for jumper headers on a board. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a system for supporting ISA-bus applications software on a PCI-based hardware system. It is a further object of the present invention to provide a direct memory access controller that accepts ISA-bus interrupt controller commands and accesses and that translates these into PCI-bus equivalent interrupt controller commands and accesses. It is a still further object of the present invention to emulate an ISA-bus interrupt controller that accepts and responds to direct memory access controller commands and accesses for execution by a PCI-bus interrupt controller mapped into a PCI-bus memory resource. Briefly, a circuit embodiment of the present invention comprises a PCI-PCI bridge core integrated on the same chip as a PCI-bus audio accelerator. An advantage of the present invention is that more functionality can be implemented on both PCI-bus add-in cards and motherboards. These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments which are illustrated in the various drawing figures. IN THE DRAWINGS FIG. 1 is a functional block diagram of a PC system embodiment of the present invention; and FIG. 2 is a function block diagram of an audio accelerator with an auxiliary integrated PCI-PCI bridge core. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates a personal computer (PC) embodiment of the present invention, referred to herein by the general reference numeral 10. The PC 10 comprises a microprocessor (CPU) 12, a system controller (Northbridge "NB") 14, and a peripheral component interconnect (PCI) bus 16. A peripheral-bus controller (Southbridge "SB") 18 provides a bridge to several buses including an industry standard architecture (ISA) bus 20. A PCI-bus audio accelerator peripheral 22 includes a PCI-bus resident audio accelerator 24 and a PCI-PCI bridge 26 both integrated as cores on the same integrated circuit (IC). The PCI-PCI bridge 26 provides more slots on a secondary PCI-bus 28 for a plurality of input-output (I/O) controllers 30. The PCI bus is the ideal medium for utilization as a multimedia interface due to its high bandwidth, support for bus mastering, and low demands on CPU capacity. By using the PCI bus as a multimedia bridge, multimedia subsystems can be designed on a adapter, e.g., PCI-bus expansion card, for different target markets. The high level of integration achieved by using embedded PCI-to-PCI technology is valuable where motherboard form factors decreased in size and yet the number of multimedia functions expand. In one embodiment, the system controller 14 comprises an Advanced Micro-Devices (Sunnyvale, Calif.) AMD-640 system controller ("Northbridge") has a 64-bit Socket-7 interface, integrated writeback cache controller, system memory controller, and PCI bus controller. Such Socket-7 interface is optimized for the AMD-K6 processor, providing 3-1-1-1-1-1-1-1 transfer timing for both read and write transactions from PBSRAM at 66 MHz. (The number sequence refers to the CPU clock "t" cycles for each operation, i.e., 3-1-1-1 means the first data will be available at the third "t" when issue the operation, then the consequence data only need additional one "t" cycle, and so on.) The AMD-640's internal memory controller has a data buffering design that uses four cache lines, e.g., sixteen quadwords, of processor-to-DRAM or cache-to-DRAM write buffering with concurrent writeback capability to accelerate writeback and write-miss cycles. The integrated PCI bus controller does concurrent processor and PCI operation with a five-doubleword posted write buffer. PCI concurrency with DRAM or cache memory is achieved through a 48-doubleword post write buffer and 26-doubleword prefetch buffer. Byte-merging is used to optimize processor-to-PCI throughput and reduce PCI bus traffic by converting consecutive processor addresses into burst PCI cycles. The AMD-640 system controller uses a variety of techniques to minimize PCI initiator read latency and DRAM access, including snoop ahead, snoop filtering, forwarding cache writebacks to the PCI initiator, and merging L1 writebacks into the PCI-posted write buffers to minimize PCI initiator read latency and DRAM utilization. To minimize snoop overhead, the integrated PCI controller supports enhanced PCI bus commands, such as memory-read-line, memory-read-multiple, and memory-write-invalidate. The combination allows a PCI initiator to achieve the full 133-Mbps burst transfer rate. In another embodiment, the peripheral-bus controller 18 comprises an AMD-645 peripheral bus controller ("Southbridge"). The AMD-645 has an integrated ISA bus controller, enhanced master mode PCI EIDE controller with Ultra DMA/33 technology, an ACPI-compatible power management unit, a USB controller, a PS2-compatible keyboard/mouse controller, and a real-time clock (RTC) with extended 256-byte CMOS RAM. The on-chip EIDE controller has a dual-channel DMA engine capable of interlaced dual-channel commands. High-bandwidth PCI transfers are achieved by a sixteen double-word data FIFO with full scatter and gather capability. The integrated USB controller has a root hub with two ports having 18-level-deep data FIFOs and built-in physical layer transceivers. The AMD-645 peripheral bus controller is marketed as meeting Microsoft Windows® 95 Plug-and-Play requirements with steerable PCI interrupts, ISA interrupts, and DMA channels. The integrated power management unit is compliant with ACPI and APM and provides dedicated input pins for external modem ring indication and power-on, five general-purpose I/O pins with option for I2C port, and sixteen general-purpose pins that can be programmed as inputs or outputs. To manage power management events, the AMD-645 controller includes an ACPI power management timer, a GP0 timer, a GP1 timer, a secondary event timer, and a conserve mode timer. Two types of sleep states, e.g., soft-off and power-on suspend, are supported with hardware automatic wake-up. Additional functionality includes event monitoring, CPU clock throttling, hardware and software-based event handling, and multiple external SMI sources. The PCI-bus audio accelerator peripheral 22 or PCI-expansion card may comprise an ESS Technology (Fremont, Cailf.) PCI audio accelerator chip, e.g., marketed as MAESTRO-1™. At a minimum, the PCI-bus audio accelerator peripheral 22 is preferably compliant with major industry standards including the Audio Subsystem Specification of PC97, Windows 95 DirectSound™, Windows Sound System, AC 1 97 CODEC Interface, and the PCI 2.1 Bus Specification. The Maestro-1 is a dual audio-engine architecture that comprises of a 64-voice, pipelined, wavetable synthesizer and a programmable audio signal processor that can simultaneously handle multiple audio streams of different data types, high-quality music synthesis, and voice compression and decompression. Wavetable technology uses algorithms to frequency shift a stored digitized sound sample of the instrument playing to create the various notes, tones and octaves of a performance Market acceptance of early PC wavetable sound solutions was hampered by a lack of compatibility with software developed for the SOUNDBLASTER standard and the high cost of the first implementations. Software compatibility has now been resolved by vendors such as ESS Technology through hardware legacy support. ESS Technology's solution, Transparent DMA, creates a virtual ISA bus that interfaces with the PCI bus. The expense of the first wavetable synthesis devices has also now been driven down, in part through the use of techniques such as downloadable sound fonts that also enhance performance. The first wavetable synthesis PC audio solutions utilized ROM to store the sound samples needed to generate sound. The ROM was expensive and limited the number of sounds that a wavetable engine could produce. Also, because the audio samples were loaded by the hardware device vendor, the software developer had no control over how their application would sound with a given vendor's wavetable hardware accelerator. ESS Technology's PC audio solutions utilize the high bandwidth PCI bus and WaveCache58 technology to store MIDI sound samples in a PC's main memory. The down loadable sound samples saves the cost of ROM and allows a software developer to determine precisely how their title will sound on every system that utilizes downloadable sound fonts. FIG. 2 illustrates a PCI-bus audio accelerator peripheral 50 that is similar to the audio accelerator peripheral 22 of FIG. 1. The PCI-bus audio accelerator peripheral 50 comprises a PCI-interface 52, a SOUNDBLASTER datapath 54, a wave processor 56, a 512×16 wave cache 58, an application specific signal processor (ASSP) 60, a ring bus 62, a SIO-2 codec 64, a SIO-1 codec 66, and an I 2 S serial interface 68. A high-performance game port (HPGP) 70 provides an interface for a joystick, and a general purpose input-output port (GPI/0) 72 provides connections to multiplexed buses. A PCI-PCI bridge 74 serves to expand the number of PCI-bus peripheral cards that the PCI-CPU 12 can address. The wave processor 56 is a dual-engine, sixty-four-channel, pipelined wave processor. The ASSP 60 is a programmable audio signal processor. Together these provide simultaneous support for multiple audio streams of different types. Such architecture enables complex, three-dimension positional gaming sound effects to be implemented while also supporting voice communications over the Internet from multiple sources. Embodiments of the present invention preferably support sixty-four independently programmable wave processor channels and provide for DIRECTSOUND® hardware acceleration with digital mixing of up to thirty-two wave streams. Audio streams of any frequency are converted to forty-eight kHz. Each of the sixty-four channels can be assigned its own parameters to control panning, tremolo, vibrato, and tone-filtering. The channels also support independently programmable special effects, e.g., reverb, chorus, flange, echo, and three-dimension spatial enhancements to create positional special effects. The high bandwidth PCI-bus is used to store MIDI-samples in main memory. Downloadable sound samples relieve needing ROM-type memory to store sound fonts, a allow software developers to control the sound PCI-bus audio accelerators. A more obvious advantage that the PCI bus brings to audio applications is sheer bandwidth. At 133 MB/second, the PCI bus represents a much larger "pipe" than the 7 MB/second ISA bus. In addition to being able to move large amounts of data quickly through the bus, PCI accelerators are able to transfer multiple data streams with different destinations during a single bus master cycle. Because PCI audio accelerators can support multiple data streams of different types, it can also reduce the latencies typically associated with Internet-based interactive audio, phone and conferencing applications. Although the present invention has been described in terms of the presently preferred embodiments, it is to be understood that the disclosure is not to be interpreted as limiting. Various alterations and modifications will no doubt become apparent to those skilled in the art after having read the above disclosure. Accordingly, it is intended that the appended claims be interpreted as covering all alterations and modifications as fall within the true spirit and scope of the invention.
A semiconductor device with an embedded PCI 2.1 compliant bridge provides expanded functionality as system-level implementations of a PCI-to-PCI bridge, and enhances the level of integration possible. The embedded PCI-to-PCI bridge allows the creation of multi-function, multimedia add-on cards supporting multiple devices. Multi-function, multimedia subsystems that provide audio, graphics, MPEG, etc., are mapped into a bridged-to PCI-bus that keeps such traffic off the main PCI-bus. The advantage for the system or add-in card vendor is that the various multimedia chips that are combined can come from different sources, providing an optimized and highly customized combination of functions.
Concisely explain the essential features and purpose of the concept presented in the passage.
[ "FIELD OF THE INVENTION The present invention relates to digital electronic circuits, and more particularly to personal computer PCI-bus systems.", "DESCRIPTION OF THE PRIOR ART The peripheral component interface (PCI) bus has become the interface bus of choice for high-speed devices because it is well-equipped to handle newer, more demanding applications with its 32-bit data path, 33 MHz clock speed and a maximum data transfer rate of 132 MB/sec.", "However, PCI loading constraints limit the number of devices that can be supported directly on a system motherboard or through expansion slots, so PCI-to-PCI bridge chips have been developed by a number of major suppliers to increase the number of available system expansion slots.", "Embedding a bridge in a semiconductor device that also supplies other functionality provides a higher degree of integration and enables the creation of multi-function, multimedia expansion cards, where a single add-in card could support audio, graphics acceleration and video conferencing.", "The PCI bus is typically isolated from the CPU local bus by a PCI controller, a so-called "Northbridge".", "The CPU can thereby write data to PCI peripherals and go on to its next operation rather than waiting for the transfer to complete.", "The PCI controller stores the data in its buffer, and sends it out later at the most efficient rate.", "The PCI-bus supports intelligent-device bus mastering, so other masters can take control of the bus and do their jobs independent of the CPU.", "The CPU can run in parallel with the bus master peripheral because of the buffered design.", "The number of PCI peripheral devices that can be supported by a single PCI-bus is based on the electrical loading constraints defined in the industry-standard "PCI 2.1 Specification".", "A compliant PCI-bus is capable of supporting a total of ten loads, and two loads are consumed by the basic PCI chipset associated with the CPU.", "PC-device controllers that are built into the motherboard present only a single load.", "A single PCI-bus can therefore only support four expansion slots without violating the specification's loading constraints, e.g., one PCI device per expansion slot.", "High-end system designers have recently begun to build systems using PCI-to-PCI bridges to provide more expansion slots on the motherboard.", "The PCI bus specifications provide for an automatic configuration of any adapter or peripheral plugged into the bus to eliminate conflicts between boards in the system and the need for jumper headers on a board.", "SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a system for supporting ISA-bus applications software on a PCI-based hardware system.", "It is a further object of the present invention to provide a direct memory access controller that accepts ISA-bus interrupt controller commands and accesses and that translates these into PCI-bus equivalent interrupt controller commands and accesses.", "It is a still further object of the present invention to emulate an ISA-bus interrupt controller that accepts and responds to direct memory access controller commands and accesses for execution by a PCI-bus interrupt controller mapped into a PCI-bus memory resource.", "Briefly, a circuit embodiment of the present invention comprises a PCI-PCI bridge core integrated on the same chip as a PCI-bus audio accelerator.", "An advantage of the present invention is that more functionality can be implemented on both PCI-bus add-in cards and motherboards.", "These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments which are illustrated in the various drawing figures.", "IN THE DRAWINGS FIG. 1 is a functional block diagram of a PC system embodiment of the present invention;", "and FIG. 2 is a function block diagram of an audio accelerator with an auxiliary integrated PCI-PCI bridge core.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates a personal computer (PC) embodiment of the present invention, referred to herein by the general reference numeral 10.", "The PC 10 comprises a microprocessor (CPU) 12, a system controller (Northbridge "NB") 14, and a peripheral component interconnect (PCI) bus 16.", "A peripheral-bus controller (Southbridge "SB") 18 provides a bridge to several buses including an industry standard architecture (ISA) bus 20.", "A PCI-bus audio accelerator peripheral 22 includes a PCI-bus resident audio accelerator 24 and a PCI-PCI bridge 26 both integrated as cores on the same integrated circuit (IC).", "The PCI-PCI bridge 26 provides more slots on a secondary PCI-bus 28 for a plurality of input-output (I/O) controllers 30.", "The PCI bus is the ideal medium for utilization as a multimedia interface due to its high bandwidth, support for bus mastering, and low demands on CPU capacity.", "By using the PCI bus as a multimedia bridge, multimedia subsystems can be designed on a adapter, e.g., PCI-bus expansion card, for different target markets.", "The high level of integration achieved by using embedded PCI-to-PCI technology is valuable where motherboard form factors decreased in size and yet the number of multimedia functions expand.", "In one embodiment, the system controller 14 comprises an Advanced Micro-Devices (Sunnyvale, Calif.) AMD-640 system controller ("Northbridge") has a 64-bit Socket-7 interface, integrated writeback cache controller, system memory controller, and PCI bus controller.", "Such Socket-7 interface is optimized for the AMD-K6 processor, providing 3-1-1-1-1-1-1-1 transfer timing for both read and write transactions from PBSRAM at 66 MHz.", "(The number sequence refers to the CPU clock "t"", "cycles for each operation, i.e., 3-1-1-1 means the first data will be available at the third "t"", "when issue the operation, then the consequence data only need additional one "t"", "cycle, and so on.) The AMD-640's internal memory controller has a data buffering design that uses four cache lines, e.g., sixteen quadwords, of processor-to-DRAM or cache-to-DRAM write buffering with concurrent writeback capability to accelerate writeback and write-miss cycles.", "The integrated PCI bus controller does concurrent processor and PCI operation with a five-doubleword posted write buffer.", "PCI concurrency with DRAM or cache memory is achieved through a 48-doubleword post write buffer and 26-doubleword prefetch buffer.", "Byte-merging is used to optimize processor-to-PCI throughput and reduce PCI bus traffic by converting consecutive processor addresses into burst PCI cycles.", "The AMD-640 system controller uses a variety of techniques to minimize PCI initiator read latency and DRAM access, including snoop ahead, snoop filtering, forwarding cache writebacks to the PCI initiator, and merging L1 writebacks into the PCI-posted write buffers to minimize PCI initiator read latency and DRAM utilization.", "To minimize snoop overhead, the integrated PCI controller supports enhanced PCI bus commands, such as memory-read-line, memory-read-multiple, and memory-write-invalidate.", "The combination allows a PCI initiator to achieve the full 133-Mbps burst transfer rate.", "In another embodiment, the peripheral-bus controller 18 comprises an AMD-645 peripheral bus controller ("Southbridge").", "The AMD-645 has an integrated ISA bus controller, enhanced master mode PCI EIDE controller with Ultra DMA/33 technology, an ACPI-compatible power management unit, a USB controller, a PS2-compatible keyboard/mouse controller, and a real-time clock (RTC) with extended 256-byte CMOS RAM.", "The on-chip EIDE controller has a dual-channel DMA engine capable of interlaced dual-channel commands.", "High-bandwidth PCI transfers are achieved by a sixteen double-word data FIFO with full scatter and gather capability.", "The integrated USB controller has a root hub with two ports having 18-level-deep data FIFOs and built-in physical layer transceivers.", "The AMD-645 peripheral bus controller is marketed as meeting Microsoft Windows® 95 Plug-and-Play requirements with steerable PCI interrupts, ISA interrupts, and DMA channels.", "The integrated power management unit is compliant with ACPI and APM and provides dedicated input pins for external modem ring indication and power-on, five general-purpose I/O pins with option for I2C port, and sixteen general-purpose pins that can be programmed as inputs or outputs.", "To manage power management events, the AMD-645 controller includes an ACPI power management timer, a GP0 timer, a GP1 timer, a secondary event timer, and a conserve mode timer.", "Two types of sleep states, e.g., soft-off and power-on suspend, are supported with hardware automatic wake-up.", "Additional functionality includes event monitoring, CPU clock throttling, hardware and software-based event handling, and multiple external SMI sources.", "The PCI-bus audio accelerator peripheral 22 or PCI-expansion card may comprise an ESS Technology (Fremont, Cailf.) PCI audio accelerator chip, e.g., marketed as MAESTRO-1™.", "At a minimum, the PCI-bus audio accelerator peripheral 22 is preferably compliant with major industry standards including the Audio Subsystem Specification of PC97, Windows 95 DirectSound™, Windows Sound System, AC 1 97 CODEC Interface, and the PCI 2.1 Bus Specification.", "The Maestro-1 is a dual audio-engine architecture that comprises of a 64-voice, pipelined, wavetable synthesizer and a programmable audio signal processor that can simultaneously handle multiple audio streams of different data types, high-quality music synthesis, and voice compression and decompression.", "Wavetable technology uses algorithms to frequency shift a stored digitized sound sample of the instrument playing to create the various notes, tones and octaves of a performance Market acceptance of early PC wavetable sound solutions was hampered by a lack of compatibility with software developed for the SOUNDBLASTER standard and the high cost of the first implementations.", "Software compatibility has now been resolved by vendors such as ESS Technology through hardware legacy support.", "ESS Technology's solution, Transparent DMA, creates a virtual ISA bus that interfaces with the PCI bus.", "The expense of the first wavetable synthesis devices has also now been driven down, in part through the use of techniques such as downloadable sound fonts that also enhance performance.", "The first wavetable synthesis PC audio solutions utilized ROM to store the sound samples needed to generate sound.", "The ROM was expensive and limited the number of sounds that a wavetable engine could produce.", "Also, because the audio samples were loaded by the hardware device vendor, the software developer had no control over how their application would sound with a given vendor's wavetable hardware accelerator.", "ESS Technology's PC audio solutions utilize the high bandwidth PCI bus and WaveCache58 technology to store MIDI sound samples in a PC's main memory.", "The down loadable sound samples saves the cost of ROM and allows a software developer to determine precisely how their title will sound on every system that utilizes downloadable sound fonts.", "FIG. 2 illustrates a PCI-bus audio accelerator peripheral 50 that is similar to the audio accelerator peripheral 22 of FIG. 1. The PCI-bus audio accelerator peripheral 50 comprises a PCI-interface 52, a SOUNDBLASTER datapath 54, a wave processor 56, a 512×16 wave cache 58, an application specific signal processor (ASSP) 60, a ring bus 62, a SIO-2 codec 64, a SIO-1 codec 66, and an I 2 S serial interface 68.", "A high-performance game port (HPGP) 70 provides an interface for a joystick, and a general purpose input-output port (GPI/0) 72 provides connections to multiplexed buses.", "A PCI-PCI bridge 74 serves to expand the number of PCI-bus peripheral cards that the PCI-CPU 12 can address.", "The wave processor 56 is a dual-engine, sixty-four-channel, pipelined wave processor.", "The ASSP 60 is a programmable audio signal processor.", "Together these provide simultaneous support for multiple audio streams of different types.", "Such architecture enables complex, three-dimension positional gaming sound effects to be implemented while also supporting voice communications over the Internet from multiple sources.", "Embodiments of the present invention preferably support sixty-four independently programmable wave processor channels and provide for DIRECTSOUND® hardware acceleration with digital mixing of up to thirty-two wave streams.", "Audio streams of any frequency are converted to forty-eight kHz.", "Each of the sixty-four channels can be assigned its own parameters to control panning, tremolo, vibrato, and tone-filtering.", "The channels also support independently programmable special effects, e.g., reverb, chorus, flange, echo, and three-dimension spatial enhancements to create positional special effects.", "The high bandwidth PCI-bus is used to store MIDI-samples in main memory.", "Downloadable sound samples relieve needing ROM-type memory to store sound fonts, a allow software developers to control the sound PCI-bus audio accelerators.", "A more obvious advantage that the PCI bus brings to audio applications is sheer bandwidth.", "At 133 MB/second, the PCI bus represents a much larger "pipe"", "than the 7 MB/second ISA bus.", "In addition to being able to move large amounts of data quickly through the bus, PCI accelerators are able to transfer multiple data streams with different destinations during a single bus master cycle.", "Because PCI audio accelerators can support multiple data streams of different types, it can also reduce the latencies typically associated with Internet-based interactive audio, phone and conferencing applications.", "Although the present invention has been described in terms of the presently preferred embodiments, it is to be understood that the disclosure is not to be interpreted as limiting.", "Various alterations and modifications will no doubt become apparent to those skilled in the art after having read the above disclosure.", "Accordingly, it is intended that the appended claims be interpreted as covering all alterations and modifications as fall within the true spirit and scope of the invention." ]
FIELD OF THE INVENTION [0001] The present invention relates to methods and devices for preventing the formation of pinholes in the production of laminates of non-woven webs and polymer film. In particular, these laminates have spaced laminated strips of non-woven webs and film with areas of nonlaminated film therebetween (herein referred to as “zone laminates”). BACKGROUND OF THE INVENTION [0002] Methods of making microporous film products have been known for some time. For example, U.S. Pat. No. 3,832,267, to Liu, teaches the melt-embossing of a polyolefin film containing a dispersed amorphous polymer phase prior to stretching or orientation to improve gas and moisture vapor transmission of the film. According to the Liu '267 patent, a film of crystalline polypropylene having a dispersed amorphous polypropylene phase is embossed prior to biaxially drawing (stretching) to produce an oriented imperforate film having greater permeability. The dispersed amorphous phase serves to provide microvoids to enhance the permeability of the otherwise imperforate film to improve moisture vapor transmission (MVT). The embossed film is preferably embossed and drawn sequentially. [0003] Many other patents and publications disclose the phenomenon of making microporous thermoplastic film products. For example, European patent 141,592 discloses the use of a polyolefin, particularly ethylene vinyl acetate (EVA) containing a dispersed polystyrene phase which, when stretched, produces a voided film which improves the moisture vapor permeability of the film. The EP '592 patent also discloses the sequential steps of embossing the EVA film with thick and thin areas followed by stretching to first provide a film having voids which, when further stretched, produces a net-like product. U.S. Pat. Nos. 4,596,738 and 4,452,845 also disclose stretched thermoplastic films where the dispersed phase may be a polyethylene filled with calcium carbonate to provide the microvoids upon stretching. Later U.S. Pat. Nos. 4,777,073; 4,921,653; and 4,814,124 disclose the same processes described by the above-mentioned earlier publications involving the steps of first embossing a polyolefin film containing a filler and then stretching that film to provide a microporous product. [0004] U.S. Pat. Nos. 4,705,812 and 4,705,813 disclose microporous films having been produced from a blend of linear low density polyethylene (LLDPE) and low density polyethylene (LDPE) with barium sulfate as the inorganic filler having an average particle diameter of 0.1-7 microns. It is also know to modify blends of LLDPE and LDPE with a thermoplastic rubber such as KRATON. Other patents such as U.S. Pat. No. 4,582,871 disclose the use of thermoplastic styrene block tripolymers in the production of microporous films with other incompatible polymers such as styrene. There are other general teachings in the art such as the disclosures in U.S. Pat. Nos. 4,921,652 and 4,472,328. [0005] The stretching, as discussed above, results in the appearance of stripes along the length of the web. These stripes are caused by the difference in appearance between the highly stretched areas, occurring between the digits on the interdigital rolls, and the areas at the digits which are not as highly stretched. These methods result in stripes of highly stretched, highly porous areas adjacent moderately stretched, but still substantially porous, areas. [0006] Relevant patents regarding extrusion lamination of unstretched non-woven webs include U.S. Pat. Nos. 2,714,571; 3,058,868; 4,522,203; 4,614,679; 4,692,368; 4,753,840 and 5,035,941. The above '863 and '368 patents disclose stretching extruded polymeric films prior to laminating with unstretched non-woven fibrous webs at pressure roller nips. The '203 and '941 patents are directed to co-extruding multiple polymeric films with unstretched non-woven webs at pressure roller nips. The '840 patent discloses preforming non-woven polymeric fiber materials prior to extrusion laminating with films to improve bonding between the non-woven fibers and films. More specifically, the '840 patent discloses conventional embossing techniques to form densified and undensified areas in non-woven base plies prior to extrusion lamination to improve bonding between non-woven fibrous webs and films due to the densified fiber areas. The '941 patent also teaches that unstretched non-woven webs that are extrusion laminated to single-ply polymeric films are susceptible to pinholes caused by fibers extending generally vertically from the plane of the fiber substrate and, accordingly, this patent discloses using multiple co-extruded film plies to prevent pinhole problems. Furthermore, methods for bonding loose non-woven fibers to polymeric film are disclosed in U.S. Pat. Nos. 3,622,422; 4,379,197 and 4,725,473. [0007] U.S. patent application Ser. No. 08/547,059 (herein incorporated by reference in its entirety), now abandoned, discloses a process and apparatus to continuously perform web splitting, separating, guiding and laminating steps in a single unit. A single wide web of a non-woven is slit into a number of narrow webs which are separated by the use of turning bars and steered into a laminator. More specifically, a web is unrolled from a wide roll of non-woven material. The incoming web is slit into narrow webs, the narrow webs move down line to turning bars which are displaced one from the other by a desired web separation distance. The spaced narrow webs are then guided into a nip of rollers for extrusion lamination with a polymer film. A molten polymer is extruded into the nip at a temperature above its softening point to form a polymeric film laminated to the narrow webs. The compressive force between the webs and the extrudate at the nip is controlled to bond one surface of the web to the film to form the laminate. The resulting laminate includes spaced strips of non-woven laminated to the polymer film with areas of nonlaminated film between the strips. [0008] U.S. patent application Ser. No. 08/722,286 (herein incorporated by reference in its entirety), a Continuation-In-Part of U.S. patent application Ser. No. 08/547,059, discloses a process and apparatus to continuously perform lamination of a polymer to another material to which it is laminated. The '286 application is directed to a process and apparatus to continuously perform non-woven web splitting, folding, guiding and laminating steps in a single unit. Depending on the spacing between folded webs, each strip of polymer may include a loose flap on either side of the laminate area which may be suitable for forming a barrier cuff in a diaper or other hygiene product. The spacing between folded webs determines the width of the loose polymer flap which is formed. Again, the resulting laminate includes spaced strips of non-woven laminated to the polymer film with areas of nonlaminated film between the strips. These laminates, having spaced laminated strips of non-woven and film with areas of nonlaminated film therebetween, are referred to as zone laminates. The resulting laminate includes spaced strips of non-woven laminated to the polymer film with areas of nonlaminated film between the strips. SUMMARY OF THE INVENTION [0009] With the development of the above referenced zone laminates, it has been discovered that pin-holes form at the boundary area between the laminated and non-laminated areas when the zone laminate is made microporous by stretching across the length of the strip. The method and apparatus of the present invention prevents the formation of pin-holes during such stretching of zone laminates. Pinholes are prevented by creating slack areas along the length of the web where the edges of the non-woven strips meet with the polymer film, pressing the slack areas into interdigital stretching rollers without stretching the slack areas, and stretching the remainder of the web by interdigitation. The slack regions are formed prior to interdigitation by, for example, formation of a furrow, a fold or a corrugation. [0010] In one embodiment, the present invention includes a first interdigital roller and a second interdigital roller and at least one disc for contacting a slack area in the laminate and pressing the slack area into the first interdigital roller without stretching the slack area. In a preferred form, the device includes at least one disc which interengages with spaced rollers to create a slack area along the length of a laminate, the interengaged disc and rollers being laterally adjustable to create the slack area in a predetermined position on the width of the web. [0011] These and other advantages and features, which characterize the invention, are set forth in the claims. For a better understanding of the invention, and of the advantages and objectives attained through its use, reference should be made to the Drawings, and to the accompanying descriptive matter, in which exemplary embodiments of the invention are described. BRIEF DESCRIPTION OF THE DRAWINGS [0012] [0012]FIG. 1 is a schematic perspective view showing an apparatus for pinhole prevention in zone laminates in accordance with one embodiment of the present invention. [0013] [0013]FIG. 2 is a cross-sectional view showing an apparatus for pinhole prevention suitable for use in accordance with one embodiment of the present invention. [0014] [0014]FIG. 3 is a cross-sectional view taken along line 3 - 3 of FIG. 2 of spacer discs and a furrow disc suitable for creating a slack area in a laminate in accordance with the present invention. [0015] [0015]FIG. 3A is an enlarged plan view of the spacer discs and furrow discs shown in FIG. 3. [0016] [0016]FIG. 4 is a cross-sectional view taken along line 4 - 4 of FIG. 2 of the presser disc forcing the laminate into the grooves on the first interdigital roller in accordance with one embodiment of the present invention. [0017] [0017]FIG. 5 is a cross-sectional view taken along line 5 - 5 of FIG. 2 showing the intersection of the first and second interdigital rollers used for stretching the laminate in the cross machine direction. [0018] [0018]FIG. 6 is a plan view of a progressive roll former suitable for use in creating a slack area in the laminate in accordance with one embodiment of the present invention. [0019] [0019]FIG. 7 is a cross-sectional view taken along line 7 - 7 of FIG. 6. [0020] [0020]FIG. 8 is a schematic perspective view of a corrugator suitable for creating a slack area in the non-woven laminate suitable for use in the present invention. [0021] [0021]FIG. 9 is a cross-sectional view taken along line 9 - 9 of FIG. 8. [0022] [0022]FIG. 10 is a graph showing the relationship between line speed and screw RPM of an extruder for use with the present invention. [0023] [0023]FIG. 11 is a graph demonstrating the relationship between moisture vapor transmission properties and incremental stretching. [0024] [0024]FIG. 12 is a graph showing the relationship between moisture vapor transmission rate and finish roll temperature prior to CD intermeshing. [0025] [0025]FIG. 13 is an enlarged schematic cross-sectional view of the boundary area of the laminate after interdigital stretching. DETAILED DESCRIPTION [0026] The method and apparatus of the present invention prevent the formation of pin-holes at the boundary area of a zone laminate at the edges of a non-woven strip during interdigital stretching. Pin-holes form at the edge of the non-woven strip because the film and non-woven laminate is substantially stronger than the adjacent unlaminated polymer film; therefore, substantially all of the stretching occurs in the unlaminated film of the boundary area. It has been discovered that this excessive stretching in the boundary areas causes the formation of pin-holes. [0027] In order to prevent pin-holing, the present invention provides for the formation of a slack area 10 a at the boundary areas of the laminate, that is, where the edge of the non-woven strips 14 meet the polymer film 12 in laminate 10 , as shown in FIGS. 1, 3A and 13 . In order to create these slack areas a number of spacer discs 18 which are slidably mounted on axle 16 are positioned such that the gap between adjacent discs 18 align with the boundary areas. Furrow discs 22 are slidably mounted on axle 20 so that each furrow disc 22 is received in the gap between adjacent spacer discs 18 at the boundary areas. A set of two spacer discs 18 and one furrow disc 22 interengage (as shown in FIGS. 3 and 3a) to create a slack area 10 a along the length of the laminate 10 . The laminate 10 , including slack area 10 a , travels to the first interdigital roller 26 where the slack area is forced into the interdigital grooves 28 on roller 26 by presser disc 32 . Presser disc 32 includes a presser area 34 which conforms to the cross section of grooves 28 . The presser discs 32 force slack area 10 a into the grooves 28 on the first interdigital roller 26 and form taut 37 areas along the remaining width of laminate 10 . The taut areas 37 pass between first roller 26 and second roller 38 and are stretched by interdigital grooves 28 and 40 to form microporous laminate 50 . [0028] The microporous laminate may optionally be stretched along the length of microporous laminate 50 to increase porosity. The lengthwise stretching may be performed by any known method of forming micropores such as interdigital rolling or differential speed stretching of the laminate 10 either before or after stretching in the cross-machine direction. [0029] As can be seen in FIG. 2, spacer discs 18 are mounted upon axle 16 by collar 18 a and set screw 18 b . Furrow discs 22 are mounted upon axle 20 by collar 22 a and set screw 22 b . Axle 20 is mounted upon a rotatable axle support 20 a which pivots from a nonengaged position to an engaged position (shown in FIG. 2). The capacity to move furrow discs 22 to a nonengaged position allows for simplified threading of laminate 10 between spacer discs 18 and furrow discs 22 . When engaged, a furrow disc 22 is interengaged with a pair of spacer discs 18 to form a furrow which creates slack area 10 a at the boundary areas of laminate 10 . Interdigital roll 26 is rotatably mounted on axle 24 and presser discs 32 are rotatably mounted on axle 30 . Presser discs 32 are movable along the length of axle 30 by collar 32 a and set screw 32 b . Presser discs 32 are movable along axle 30 in a method similar to the movement of furrow discs 22 along axle 20 as discussed above. The presser disc 32 includes a presser area 34 around its periphery which is complimentary to the grooves on roll 26 . Presser area 34 presses the slack area 10 a of laminate 10 into the grooves 28 on roll 26 without stretching of the slack area 10 a . The width of the laminate 10 , other than the slack areas 10 a , are held taut against the grooves of roller 26 so that the taut areas 37 are interdigitally stretched between roller 26 and roller 38 . [0030] The intermeshing rollers 26 , 38 are capable of large engagement depths which may stretch the laminate up to about 200% or more of the original width to form the micropores. The equipment incorporates a controller (not shown) for the shafts 24 , 36 of the two intermeshing rollers 26 , 38 to control the degree of intermeshing and hence the amount of stretching imparted to the laminate. The controller also keeps shafts 24 , 36 parallel when the top shaft is raised or lowered to assure that the teeth of one intermeshing roller always fall between the teeth of the other intermeshing roller to avoid potentially damaging physical contact between intermeshing teeth. This parallel motion is assured by a rack and gear arrangement (not shown) wherein a stationary gear rack is attached to each side frame in juxtaposition to vertically slidable members. A shaft traverses side frames and operates a bearing in each of the vertically slidable members. A gear resides on each end of the shaft and operates in engagement with the racks to produce the desired parallel motion. [0031] As shown in FIG. 3, the force of furrow discs 22 between spacer discs 18 causes the formation of a furrow to form slack area 10 a between spacer discs 18 . As shown in detail in FIG. 3A the slack area 10 a is preferably formed at the boundary areas of the zone laminate where the edges of the non-woven 14 meet polymer film 12 . The laminate 10 , including slack areas 10 a , travels from spacer discs 18 and furrow discs 22 to the first interdigitating roller 26 . As the first interdigitating roller 26 rotates about axle 24 , slack area 10 a is pressed into the grooves 28 of the first interdigitating roller 26 by the complimentary structure 34 of presser rollers 32 , as shown in FIG. 4. Due to the creation of the slack area 10 a , the laminate 10 is pressed into grooves 28 to form taut areas 37 but without stretching the web. The web then rotates about first interdigitating roller 26 to meet second interdigitating roller 38 . Interdigitating roller 38 rotates about axle 36 and grooves 40 intermesh with grooves 28 to stretch the taut areas 37 of laminate in the cross-machine direction, that is, substantially no stretching occurs where the slack areas 10 a have been pressed into the grooves 28 on the first roller 26 . [0032] As can be seen in FIG. 3 the spacer discs 18 may be variously positioned along axle 16 by use of clamping collars 18 a and clamping screws 18 b . Each furrow disc 22 includes a clamping collar 22 a with a set screw 22 b to allow the furrow disc to be variably positioned along axle 20 . Similarly, presser discs 32 include clamping collar 32 a and set screw 32 b to allow the presser discs 32 to be variably positioned along axle 30 . This adjustability allows for the processing of various widths of laminate without the need for substantial time spent setting up the machinery. [0033] As seen in FIG. 4 and 5 , presser disc 32 interengages with grooves 28 on interdigital roll 26 by complimentary presser area 34 such as circumferential grooves to interact with a cross directional interdigital stretcher, a helical gear to interengage with a diagonal intermeshing stretcher, or a deformable member which conforms to the surface of roll 26 . Presser roller 32 forces the slack area 10 a of laminate 10 into the grooves of roller 26 so that the taut areas 37 of laminate 10 are formed on either side of the presser roller 32 . These taut areas 37 are subsequently stretched between interdigital rollers 26 , 38 to form the microporous zone laminated sheet 50 having substantially unstretched portions along the length thereof. FIG. 13 shows the stretched laminate 50 including micropores 12 a in the taut areas 37 of the polymer film 12 and the lack of micropores in the boundary area. [0034] Other methods of forming a slack area 10 a are shown in FIGS. 6 - 9 . As shown in FIGS. 6 and 7 a progressive roll former 100 which includes a series of increasingly overlapped rollers may be used to create slack area 10 a . The first set of rollers 102 a , 104 a , 106 a deform the laminate 10 to form a small slack area. The second set of rollers 102 b , 104 b , 106 b have a larger overlap and thus form a larger slack area. The third set of rollers 102 c , 104 c , 106 c are overlapped to form a slack area 10 a of the desired shape. [0035] A corrugator 120 , as seen in FIGS. 8 and 9 include a first support plate 122 having a female corrugator 124 and a second support plate 126 which includes male corrugator section 128 . The male 128 and female 124 corrugator sections have an increasing cross-sectional area along the length of the web and are nested to cause the laminate 10 to deform and thus create slack area 10 a. [0036] The laminate of the present invention may be achieved with the use of a wide variety of polymer films; however, in a preferred form the film is manufactured by first melt blending a composition of: [0037] (a) about 35% to about 45% by weight of a linear low density polyethylene, [0038] (b) about 3% to about 10% by weight of a low density polyethylene, [0039] (c) about 40% to about 50% by weight calcium carbonate filler particles, and [0040] (d) about 2% to about 6% by weight of a triblock copolymer of styrene selected from the group consisting of styrene-butadiene-styrene, styrene-isoprene-styrene, and styrene-ethylene-butylene-styrene, and blends thereof, [0041] extruding the melt blended composition into a nip of rollers with an air knife to form a film at a speed on the order of at least about 550 fpm to about 1200 fpm without draw resonance, and [0042] applying an incremental stretching force to the film along lines substantially uniformly across the taut areas of the laminate and throughout its depth to provide a microporous film. [0043] More particularly, in a preferred form, the melt-blended composition consists essentially of about 42% by weight LLDPE, about 4% by weight LDPE, about 44% by weight calcium carbonate filler particles having an average particle size of about 1 micron, and about 3% by weight triblock polymer, especially styrene-butadiene-styrene. If desired, the stiffness properties of the microporous film products may be controlled by including high density polyethylene on the order of about 0-5% by weight and including 0-4% by weight titanium dioxide. Typically, a processing aid such as a fluorocarbon polymer in an amount of about 0.1% to about 0.2% by weight is added, as exemplified by 1-propene, 1,1,2,3,3,3-hexafluoro copolymer with 1,1-difluoroethylene is included in the melt. The triblock polymer may also be blended with oil, hydrocarbon, antioxidant and stabilizer. [0044] Both embossed and flat films may be produced according to the principles of this invention. In the case of an embossed film, the nip of rollers comprises a metal embossing roller and a rubber roller. The compressive force between the rollers forms an embossed film of desired thickness on the order of about 0.5 to about 10 mils. It has also been found that rollers which provide a polished chrome surface form a flat film. Whether the film is an embossed film or a flat film, upon incremental stretching at high speeds, microporous film products are produced having high moisture vapor transmission rate (MVTR) within the acceptable range of about 1000 to 4000 gms/m 2 /day. It has been found that flat film can be incrementally stretched more uniformly than embossed film. The process may be conducted at ambient or room temperature or at elevated temperatures. As described above, laminates of the microporous film may be obtained with non-woven fibrous webs. [0045] The non-woven fibrous web may comprise fibers of polyethylene, polypropylene, polyesters, rayon, cellulose, nylon, and blends of such fibers. A number of definitions have been proposed for non-woven fibrous webs. The fibers are usually staple fibers or continuous filaments. The non-wovens are usually referred to as spunbond, carded, meltblown and the like. The fibers or filaments may be bicomponent to facilitate bonding. For example, a fiber having a sheath and core of different polymers such as polyethylene (PE) and polypropylene (PP) may be used or mixtures of PE and PP fibers may be used. As used herein “non-woven fibrous web” is used in its generic sense to define a generally planar structure that is relatively flat, flexible and porous, and is composed of staple fibers or continuous filaments. For a detailed description of non-wovens, see “Nonwoven Fabric Primer and Reference Sampler” by E. A. Vaughn, Association of the Non-woven Fabrics Industry, 3d Edition (1992). [0046] In a preferred form, the microporous laminate employs a film having a gauge or a thickness between about 0.25 and 10 mils and, depending upon use, the film thickness will vary and, most preferably, in disposable applications, is on the order of about 0.25 to 2 mils in thickness. The non-woven fibrous webs of the laminated sheet normally have a weight of about 5 gms/yd 2 to 75 gms/yd 2 , preferably about 20 to about 40 gms/yd 2 . The composite or laminate can be incrementally stretched in the cross-direction (CD) to form a CD stretched composite. Furthermore, CD stretching may be followed by stretching in the machine direction (MD) to form a composite which is stretched in both CD and MD directions. As indicated above, the microporous film or laminate may be used in many different applications such as baby diapers, baby training pants, catamenial pads and garments, and the like where moisture vapor and air transmission properties, as well as fluid barrier properties, are needed. [0047] The laminate is then incrementally stretched in the cross-direction (CD) or diagonally using the apparatus of the present invention to form a stretched laminate having unstretched regions along the length of the laminate. Furthermore, stretching according to the present invention may be followed by stretching in the machine direction (MD). [0048] A number of different stretchers and techniques may be employed to stretch the film or laminate of a non-woven fibrous web and microporous-formable film. These laminates of non-woven carded fibrous webs of staple fibers or non-woven spun-bonded fibrous webs may be stretched with the stretchers and techniques described as follows: [0049] The diagonal intermeshing stretcher consists of a pair of left hand and right hand helical gear-like elements on parallel shafts. The shafts are disposed between two machine side plates, the lower shaft being located in fixed bearings and the upper shaft being located in bearings in vertically slidable members. The slidable members are adjustable in the vertical direction by wedge shaped elements operable by adjusting screws. Screwing the wedges out or in will move the vertically slidable member respectively down or up to further engage or disengage the gear-like teeth of the upper intermeshing roll with the lower intermeshing roll. Micrometers mounted to the side frames are operable to indicate the depth of engagement of the teeth of the intermeshing roll. [0050] Air cylinders are employed to hold the slidable members in their lower engaged position firmly against the adjusting wedges to oppose the upward force exerted by the material being stretched. These cylinders may also be retracted to disengage the upper and lower intermeshing rolls from each other for purposes of threading material through the intermeshing equipment or in conjunction with a safety circuit which would open all the machine nip points when activated. [0051] A drive is typically utilized to drive the stationery intermeshing roller. If the upper intermeshing roller is to be disengagable for purposes of machine threading or safety, it is preferable to use an antibacklash gearing arrangement between the upper and lower intermeshing rollers to assure that upon reengagement the teeth of one intermeshing roller always falls between the teeth of the other intermeshing roller and potentially damaging physical contact between addenda of intermeshing teeth is avoided. If the intermeshing rollers are to remain in constant engagement, the upper intermeshing roll typically need not be driven. Drive may be accomplished by the driven intermeshing roller through the material being stretched. [0052] The intermeshing rollers closely resemble fine pitch helical gears. [0053] In the preferred embodiment, the rollers have 5.935″ diameter, 45° helix angle, a 0.100″ normal pitch, 30 diametral pitch, 14½° pressure angle, and are basically a long addendum topped gear. This produces a narrow, deep tooth profile which allows up to about 0.090″ of intermeshing engagement and about 0.005″ clearance on the sides of the tooth for material thickness. The teeth are not designed to transmit rotational torque and do not contact metal-to-metal in normal intermeshing stretching operation. With such a diagonal intermeshing stretcher, a presser disc 32 having the configuration of a helical gear would be used. The use of a diagonal intermeshing stretcher provides for a stretching force having force components in both the cross machine direction and the machine direction of the laminate. [0054] The drive for the CD intermeshing stretcher typically operates both upper and lower intermeshing rollers except in the case of intermeshing stretching of materials with a relatively high coefficient of friction. The drive need not be antibacklash, however, because a small amount of machine direction misalignment or drive slippage will cause no problem. [0055] The CD intermeshing elements are machined from solid material but can best be described as an alternating stack of two different diameter disks. In the preferred embodiment, the intermeshing disks would be 6″ in diameter, 0.031″ thick, and have a full radius on their edge. The spacer disks separating the intermeshing disks would be 5½″ in diameter and 0.069″ in thickness. Two rolls of this configuration would be able to be intermeshed up to 0.231″ leaving 0.019″ clearance for material on all sides. As with the diagonal intermeshing stretcher, this CD intermeshing element configuration would have a 0.100″ pitch. [0056] The MD intermeshing stretching equipment is identical to the diagonal intermeshing stretch except for the design of the intermeshing rollers. The MD intermeshing rolls closely resemble fine pitch spur gears. In the preferred embodiment, the rolls have a 5.933″ diameter, 0.100″ pitch, 30 Diametral pitch, 14½″ pressure angle, and are basically a long addendum, topped gear. A second pass was taken on these rolls with the gear hob offset 0.010″ to provide a narrowed tooth with more clearance. With about 0.090″ of engagement, this configuration will have about 0.010″ clearance on the sides for material thickness. [0057] The above described diagonal or CD intermeshing stretchers may be employed with the pin-hole prevention apparatus of the present invention to produce the incrementally stretched film or laminate of non-woven fibrous web and microporous-formable film to form the microporous film products of this invention. For example, the stretching operation may be employed on an extrusion laminate of a non-woven fibrous web of staple fibers or spun-bonded filaments and microporous-formable thermoplastic film. In one of the unique aspects of this invention, a laminate of a non-woven fibrous web of spun-bonded filaments may be incrementally stretched to provide a very soft fibrous finish to the laminate that looks like cloth. The laminate of non-woven fibrous web and microporous-formable film is incrementally stretched using, for instance, the CD and/or MD intermeshing stretcher with one pass through the stretcher with a depth of roller engagement at about 0.060 inch to 0.120 inch at speeds from about 550 fpm to 1200 fpm or faster. The results of such incremental or intermesh stretching produces laminates that have excellent breatheability and liquid-barrier properties, yet provide superior bond strengths and soft cloth-like textures. [0058] The microporous laminate typically employs a film having a gauge or a thickness between about 0.25 and 10 mils and, depending upon use, the film thickness will vary and, most preferably, in disposable applications is the order of about 0.25 to 2 mils in thickness. The non-woven fibrous webs of the laminated sheet normally have a weight of about 5 grams per square yard to 75 grams per square yard preferably about 20 to about 40 grams per square yard. [0059] The following examples illustrate the method of making microporous film and laminates of this invention. In light of these examples and this further detailed description, it is apparent to a person of ordinary skill in the art that variations thereof may be made without departing from the scope of this invention. EXAMPLES 1-5 [0060] Blends of LLDPE and LDPE having the compositions reported in the following TABLE 1 were extruded to form films and the films were then incrementally stretched to provide microporous films. TABLE 1 Formulation (by wt.) 1 2 3 4 5 CaCO 3 44.2 44.2 44.2 44.2 44.2 LLDPE 44.1 44.9 41.9 41.9 41.9 LDPE 1.5 3.7 3.7 3.7 3.7 Others* 10.2 10.2 10.2 10.2 10.2 Screw A 33 45 57 64 75 RPM B 33 45 57 64 75 Basis wt. (gms/m 2 ) 45 45 45 45 45 Gauge (mils) 2 2 2 2 2 Line Speed (fpm) 550 700 900 1000 1200 Air Knife (cfm/inch) 5-25 5-25 5-25 5-25 5-25 Web Stability Poor Good web stability without draw resonance gauge control with draw resonance [0061] Each of the formulations of 1-5 were extruded into films employing an extrusion apparatus. The formulations of Examples 1-5 were fed from an extruder through a slot die to form the extrudate into the nip of a rubber roll and a metal roll. The incoming webs of non-woven material were also introduced into the nip of the rolls. In Examples 1-5, the thermoplastic film was produced for subsequent incremental stretching to form the microporous film. As shown in TABLE 1, over speeds of about 550 fpm to 1200 fpm, a polyethylene film on the order of about 2 mils in thickness was made which is taken off the roller. The compressive force at the nip is controlled such that the film is made without pin-holing and without draw resonance in the case of Examples 2-5. The melt temperatures from the feed zone to the screw tip of extruders were maintained at about 400-430° F. with die temperatures of approximately 450° F. to extrude the precursor film around 2 mils (45 g/m 2 ). [0062] As shown in TABLE 1 , over speeds of about 550 fpm to 1200 fpm, a polyethylene film on the order of about 2 mils in thickness was made which is taken off the roller. The air knife has a length of about 120″ and an opening of about 0.035″-0.060″ and air is blown through the opening and against the extrudate at about 5 cfm/inch to 25 cfm/inch. The compressive force at the nip and the air knife are controlled such that the film is made without pin-holing and without draw resonance in the case of Examples 2-5. Where the LDPE was included in the composition at a level of 1.5% by weight, draw resonance was encountered at a line speed of 550 fpm. However, when the LDPE was included in the formulation at a level of 3.7% by weight with the LLDPE at a level of 44.1-44.9% by weight, film production was able to be achieved at high speeds greater than 550 fpm up to 1200 fpm without draw resonance. The melt temperatures from the feed zone to the screw tip of the extruders were maintained at about 400-430° F. with die temperatures of approximately 450° F. to extrude the precursor film around 2 mils (45 gms/m 2 ). [0063] [0063]FIG. 10 is a graph demonstrating the line speeds for Examples 1-5 and the necessary screw speed. Example 1 , which contained only 1.5% by weight of LDPE, resulted in a poor film gauge control with draw resonance even with the air knife. However, when the LDPE was increased to about 3.7% by weight, excellent web stability was achieved without draw resonance even when line speeds were increased to about 1200 fpm. [0064] [0064]FIG. 11 is a graph demonstrating the moisture vapor transmission properties (MVTR) of both embossed and flat films resulting from incrementally stretching the precursor films of Examples 2-5 under different temperatures and stretch roller engagement conditions. The MVTRs for the embossed film on the order of about 1200-2400 gms/m 2 /day were achieved, whereas MVTRs for the flat film on the order of about 1900-3200 gms/m 2 /day were achieved. FIG. 12 shows the impact of the temperature of the CD preheat roller upon MVTR. The MVTR for the film varied between about 2000-2900 gms/m 2 /day with the roller preheat temperature between about 75-220 F. The embossed film was made with a metal embossing roller having a rectangular engraving of CD and MD lines with about 165-300 lines per inch. This pattern is disclosed, for example, in U.S. Pat. No. 4,376,147 which is incorporated herein by reference. This micro pattern provides a matte finish to the film but is undetectable to the naked eye. [0065] Those skilled in the art will recognize that the exemplary embodiment illustrated in the drawings is not intended to limit the invention. Indeed, those skilled in the art will recognize that other alternative embodiments may be used without departing from the scope of the invention.
The method and apparatus of the present invention prevents the formation of pin-holes during stretching of strip laminates in the cross machine direction. Pin-holes are prevented by creating slack areas along the length of the web where the edges of the non-woven strips meet with the polymer film, pressing the slack areas into the interdigital stretching rollers without stretching the slack areas, and stretching the remainder of the web in a typical manner. The slack regions are formed prior to interdigitation by, for example, formation of a furrow, a fold or a corrugation.
Provide a concise summary of the essential information conveyed in the given context.
[ "FIELD OF THE INVENTION [0001] The present invention relates to methods and devices for preventing the formation of pinholes in the production of laminates of non-woven webs and polymer film.", "In particular, these laminates have spaced laminated strips of non-woven webs and film with areas of nonlaminated film therebetween (herein referred to as “zone laminates”).", "BACKGROUND OF THE INVENTION [0002] Methods of making microporous film products have been known for some time.", "For example, U.S. Pat. No. 3,832,267, to Liu, teaches the melt-embossing of a polyolefin film containing a dispersed amorphous polymer phase prior to stretching or orientation to improve gas and moisture vapor transmission of the film.", "According to the Liu '267 patent, a film of crystalline polypropylene having a dispersed amorphous polypropylene phase is embossed prior to biaxially drawing (stretching) to produce an oriented imperforate film having greater permeability.", "The dispersed amorphous phase serves to provide microvoids to enhance the permeability of the otherwise imperforate film to improve moisture vapor transmission (MVT).", "The embossed film is preferably embossed and drawn sequentially.", "[0003] Many other patents and publications disclose the phenomenon of making microporous thermoplastic film products.", "For example, European patent 141,592 discloses the use of a polyolefin, particularly ethylene vinyl acetate (EVA) containing a dispersed polystyrene phase which, when stretched, produces a voided film which improves the moisture vapor permeability of the film.", "The EP '592 patent also discloses the sequential steps of embossing the EVA film with thick and thin areas followed by stretching to first provide a film having voids which, when further stretched, produces a net-like product.", "U.S. Pat. Nos. 4,596,738 and 4,452,845 also disclose stretched thermoplastic films where the dispersed phase may be a polyethylene filled with calcium carbonate to provide the microvoids upon stretching.", "Later U.S. Pat. Nos. 4,777,073;", "4,921,653;", "and 4,814,124 disclose the same processes described by the above-mentioned earlier publications involving the steps of first embossing a polyolefin film containing a filler and then stretching that film to provide a microporous product.", "[0004] U.S. Pat. Nos. 4,705,812 and 4,705,813 disclose microporous films having been produced from a blend of linear low density polyethylene (LLDPE) and low density polyethylene (LDPE) with barium sulfate as the inorganic filler having an average particle diameter of 0.1-7 microns.", "It is also know to modify blends of LLDPE and LDPE with a thermoplastic rubber such as KRATON.", "Other patents such as U.S. Pat. No. 4,582,871 disclose the use of thermoplastic styrene block tripolymers in the production of microporous films with other incompatible polymers such as styrene.", "There are other general teachings in the art such as the disclosures in U.S. Pat. Nos. 4,921,652 and 4,472,328.", "[0005] The stretching, as discussed above, results in the appearance of stripes along the length of the web.", "These stripes are caused by the difference in appearance between the highly stretched areas, occurring between the digits on the interdigital rolls, and the areas at the digits which are not as highly stretched.", "These methods result in stripes of highly stretched, highly porous areas adjacent moderately stretched, but still substantially porous, areas.", "[0006] Relevant patents regarding extrusion lamination of unstretched non-woven webs include U.S. Pat. Nos. 2,714,571;", "3,058,868;", "4,522,203;", "4,614,679;", "4,692,368;", "4,753,840 and 5,035,941.", "The above '863 and '368 patents disclose stretching extruded polymeric films prior to laminating with unstretched non-woven fibrous webs at pressure roller nips.", "The '203 and '941 patents are directed to co-extruding multiple polymeric films with unstretched non-woven webs at pressure roller nips.", "The '840 patent discloses preforming non-woven polymeric fiber materials prior to extrusion laminating with films to improve bonding between the non-woven fibers and films.", "More specifically, the '840 patent discloses conventional embossing techniques to form densified and undensified areas in non-woven base plies prior to extrusion lamination to improve bonding between non-woven fibrous webs and films due to the densified fiber areas.", "The '941 patent also teaches that unstretched non-woven webs that are extrusion laminated to single-ply polymeric films are susceptible to pinholes caused by fibers extending generally vertically from the plane of the fiber substrate and, accordingly, this patent discloses using multiple co-extruded film plies to prevent pinhole problems.", "Furthermore, methods for bonding loose non-woven fibers to polymeric film are disclosed in U.S. Pat. Nos. 3,622,422;", "4,379,197 and 4,725,473.", "[0007] U.S. patent application Ser.", "No. 08/547,059 (herein incorporated by reference in its entirety), now abandoned, discloses a process and apparatus to continuously perform web splitting, separating, guiding and laminating steps in a single unit.", "A single wide web of a non-woven is slit into a number of narrow webs which are separated by the use of turning bars and steered into a laminator.", "More specifically, a web is unrolled from a wide roll of non-woven material.", "The incoming web is slit into narrow webs, the narrow webs move down line to turning bars which are displaced one from the other by a desired web separation distance.", "The spaced narrow webs are then guided into a nip of rollers for extrusion lamination with a polymer film.", "A molten polymer is extruded into the nip at a temperature above its softening point to form a polymeric film laminated to the narrow webs.", "The compressive force between the webs and the extrudate at the nip is controlled to bond one surface of the web to the film to form the laminate.", "The resulting laminate includes spaced strips of non-woven laminated to the polymer film with areas of nonlaminated film between the strips.", "[0008] U.S. patent application Ser.", "No. 08/722,286 (herein incorporated by reference in its entirety), a Continuation-In-Part of U.S. patent application Ser.", "No. 08/547,059, discloses a process and apparatus to continuously perform lamination of a polymer to another material to which it is laminated.", "The '286 application is directed to a process and apparatus to continuously perform non-woven web splitting, folding, guiding and laminating steps in a single unit.", "Depending on the spacing between folded webs, each strip of polymer may include a loose flap on either side of the laminate area which may be suitable for forming a barrier cuff in a diaper or other hygiene product.", "The spacing between folded webs determines the width of the loose polymer flap which is formed.", "Again, the resulting laminate includes spaced strips of non-woven laminated to the polymer film with areas of nonlaminated film between the strips.", "These laminates, having spaced laminated strips of non-woven and film with areas of nonlaminated film therebetween, are referred to as zone laminates.", "The resulting laminate includes spaced strips of non-woven laminated to the polymer film with areas of nonlaminated film between the strips.", "SUMMARY OF THE INVENTION [0009] With the development of the above referenced zone laminates, it has been discovered that pin-holes form at the boundary area between the laminated and non-laminated areas when the zone laminate is made microporous by stretching across the length of the strip.", "The method and apparatus of the present invention prevents the formation of pin-holes during such stretching of zone laminates.", "Pinholes are prevented by creating slack areas along the length of the web where the edges of the non-woven strips meet with the polymer film, pressing the slack areas into interdigital stretching rollers without stretching the slack areas, and stretching the remainder of the web by interdigitation.", "The slack regions are formed prior to interdigitation by, for example, formation of a furrow, a fold or a corrugation.", "[0010] In one embodiment, the present invention includes a first interdigital roller and a second interdigital roller and at least one disc for contacting a slack area in the laminate and pressing the slack area into the first interdigital roller without stretching the slack area.", "In a preferred form, the device includes at least one disc which interengages with spaced rollers to create a slack area along the length of a laminate, the interengaged disc and rollers being laterally adjustable to create the slack area in a predetermined position on the width of the web.", "[0011] These and other advantages and features, which characterize the invention, are set forth in the claims.", "For a better understanding of the invention, and of the advantages and objectives attained through its use, reference should be made to the Drawings, and to the accompanying descriptive matter, in which exemplary embodiments of the invention are described.", "BRIEF DESCRIPTION OF THE DRAWINGS [0012] [0012 ]FIG. 1 is a schematic perspective view showing an apparatus for pinhole prevention in zone laminates in accordance with one embodiment of the present invention.", "[0013] [0013 ]FIG. 2 is a cross-sectional view showing an apparatus for pinhole prevention suitable for use in accordance with one embodiment of the present invention.", "[0014] [0014 ]FIG. 3 is a cross-sectional view taken along line 3 - 3 of FIG. 2 of spacer discs and a furrow disc suitable for creating a slack area in a laminate in accordance with the present invention.", "[0015] [0015 ]FIG. 3A is an enlarged plan view of the spacer discs and furrow discs shown in FIG. 3. [0016] [0016 ]FIG. 4 is a cross-sectional view taken along line 4 - 4 of FIG. 2 of the presser disc forcing the laminate into the grooves on the first interdigital roller in accordance with one embodiment of the present invention.", "[0017] [0017 ]FIG. 5 is a cross-sectional view taken along line 5 - 5 of FIG. 2 showing the intersection of the first and second interdigital rollers used for stretching the laminate in the cross machine direction.", "[0018] [0018 ]FIG. 6 is a plan view of a progressive roll former suitable for use in creating a slack area in the laminate in accordance with one embodiment of the present invention.", "[0019] [0019 ]FIG. 7 is a cross-sectional view taken along line 7 - 7 of FIG. 6. [0020] [0020 ]FIG. 8 is a schematic perspective view of a corrugator suitable for creating a slack area in the non-woven laminate suitable for use in the present invention.", "[0021] [0021 ]FIG. 9 is a cross-sectional view taken along line 9 - 9 of FIG. 8. [0022] [0022 ]FIG. 10 is a graph showing the relationship between line speed and screw RPM of an extruder for use with the present invention.", "[0023] [0023 ]FIG. 11 is a graph demonstrating the relationship between moisture vapor transmission properties and incremental stretching.", "[0024] [0024 ]FIG. 12 is a graph showing the relationship between moisture vapor transmission rate and finish roll temperature prior to CD intermeshing.", "[0025] [0025 ]FIG. 13 is an enlarged schematic cross-sectional view of the boundary area of the laminate after interdigital stretching.", "DETAILED DESCRIPTION [0026] The method and apparatus of the present invention prevent the formation of pin-holes at the boundary area of a zone laminate at the edges of a non-woven strip during interdigital stretching.", "Pin-holes form at the edge of the non-woven strip because the film and non-woven laminate is substantially stronger than the adjacent unlaminated polymer film;", "therefore, substantially all of the stretching occurs in the unlaminated film of the boundary area.", "It has been discovered that this excessive stretching in the boundary areas causes the formation of pin-holes.", "[0027] In order to prevent pin-holing, the present invention provides for the formation of a slack area 10 a at the boundary areas of the laminate, that is, where the edge of the non-woven strips 14 meet the polymer film 12 in laminate 10 , as shown in FIGS. 1, 3A and 13 .", "In order to create these slack areas a number of spacer discs 18 which are slidably mounted on axle 16 are positioned such that the gap between adjacent discs 18 align with the boundary areas.", "Furrow discs 22 are slidably mounted on axle 20 so that each furrow disc 22 is received in the gap between adjacent spacer discs 18 at the boundary areas.", "A set of two spacer discs 18 and one furrow disc 22 interengage (as shown in FIGS. 3 and 3a) to create a slack area 10 a along the length of the laminate 10 .", "The laminate 10 , including slack area 10 a , travels to the first interdigital roller 26 where the slack area is forced into the interdigital grooves 28 on roller 26 by presser disc 32 .", "Presser disc 32 includes a presser area 34 which conforms to the cross section of grooves 28 .", "The presser discs 32 force slack area 10 a into the grooves 28 on the first interdigital roller 26 and form taut 37 areas along the remaining width of laminate 10 .", "The taut areas 37 pass between first roller 26 and second roller 38 and are stretched by interdigital grooves 28 and 40 to form microporous laminate 50 .", "[0028] The microporous laminate may optionally be stretched along the length of microporous laminate 50 to increase porosity.", "The lengthwise stretching may be performed by any known method of forming micropores such as interdigital rolling or differential speed stretching of the laminate 10 either before or after stretching in the cross-machine direction.", "[0029] As can be seen in FIG. 2, spacer discs 18 are mounted upon axle 16 by collar 18 a and set screw 18 b .", "Furrow discs 22 are mounted upon axle 20 by collar 22 a and set screw 22 b .", "Axle 20 is mounted upon a rotatable axle support 20 a which pivots from a nonengaged position to an engaged position (shown in FIG. 2).", "The capacity to move furrow discs 22 to a nonengaged position allows for simplified threading of laminate 10 between spacer discs 18 and furrow discs 22 .", "When engaged, a furrow disc 22 is interengaged with a pair of spacer discs 18 to form a furrow which creates slack area 10 a at the boundary areas of laminate 10 .", "Interdigital roll 26 is rotatably mounted on axle 24 and presser discs 32 are rotatably mounted on axle 30 .", "Presser discs 32 are movable along the length of axle 30 by collar 32 a and set screw 32 b .", "Presser discs 32 are movable along axle 30 in a method similar to the movement of furrow discs 22 along axle 20 as discussed above.", "The presser disc 32 includes a presser area 34 around its periphery which is complimentary to the grooves on roll 26 .", "Presser area 34 presses the slack area 10 a of laminate 10 into the grooves 28 on roll 26 without stretching of the slack area 10 a .", "The width of the laminate 10 , other than the slack areas 10 a , are held taut against the grooves of roller 26 so that the taut areas 37 are interdigitally stretched between roller 26 and roller 38 .", "[0030] The intermeshing rollers 26 , 38 are capable of large engagement depths which may stretch the laminate up to about 200% or more of the original width to form the micropores.", "The equipment incorporates a controller (not shown) for the shafts 24 , 36 of the two intermeshing rollers 26 , 38 to control the degree of intermeshing and hence the amount of stretching imparted to the laminate.", "The controller also keeps shafts 24 , 36 parallel when the top shaft is raised or lowered to assure that the teeth of one intermeshing roller always fall between the teeth of the other intermeshing roller to avoid potentially damaging physical contact between intermeshing teeth.", "This parallel motion is assured by a rack and gear arrangement (not shown) wherein a stationary gear rack is attached to each side frame in juxtaposition to vertically slidable members.", "A shaft traverses side frames and operates a bearing in each of the vertically slidable members.", "A gear resides on each end of the shaft and operates in engagement with the racks to produce the desired parallel motion.", "[0031] As shown in FIG. 3, the force of furrow discs 22 between spacer discs 18 causes the formation of a furrow to form slack area 10 a between spacer discs 18 .", "As shown in detail in FIG. 3A the slack area 10 a is preferably formed at the boundary areas of the zone laminate where the edges of the non-woven 14 meet polymer film 12 .", "The laminate 10 , including slack areas 10 a , travels from spacer discs 18 and furrow discs 22 to the first interdigitating roller 26 .", "As the first interdigitating roller 26 rotates about axle 24 , slack area 10 a is pressed into the grooves 28 of the first interdigitating roller 26 by the complimentary structure 34 of presser rollers 32 , as shown in FIG. 4. Due to the creation of the slack area 10 a , the laminate 10 is pressed into grooves 28 to form taut areas 37 but without stretching the web.", "The web then rotates about first interdigitating roller 26 to meet second interdigitating roller 38 .", "Interdigitating roller 38 rotates about axle 36 and grooves 40 intermesh with grooves 28 to stretch the taut areas 37 of laminate in the cross-machine direction, that is, substantially no stretching occurs where the slack areas 10 a have been pressed into the grooves 28 on the first roller 26 .", "[0032] As can be seen in FIG. 3 the spacer discs 18 may be variously positioned along axle 16 by use of clamping collars 18 a and clamping screws 18 b .", "Each furrow disc 22 includes a clamping collar 22 a with a set screw 22 b to allow the furrow disc to be variably positioned along axle 20 .", "Similarly, presser discs 32 include clamping collar 32 a and set screw 32 b to allow the presser discs 32 to be variably positioned along axle 30 .", "This adjustability allows for the processing of various widths of laminate without the need for substantial time spent setting up the machinery.", "[0033] As seen in FIG. 4 and 5 , presser disc 32 interengages with grooves 28 on interdigital roll 26 by complimentary presser area 34 such as circumferential grooves to interact with a cross directional interdigital stretcher, a helical gear to interengage with a diagonal intermeshing stretcher, or a deformable member which conforms to the surface of roll 26 .", "Presser roller 32 forces the slack area 10 a of laminate 10 into the grooves of roller 26 so that the taut areas 37 of laminate 10 are formed on either side of the presser roller 32 .", "These taut areas 37 are subsequently stretched between interdigital rollers 26 , 38 to form the microporous zone laminated sheet 50 having substantially unstretched portions along the length thereof.", "FIG. 13 shows the stretched laminate 50 including micropores 12 a in the taut areas 37 of the polymer film 12 and the lack of micropores in the boundary area.", "[0034] Other methods of forming a slack area 10 a are shown in FIGS. 6 - 9 .", "As shown in FIGS. 6 and 7 a progressive roll former 100 which includes a series of increasingly overlapped rollers may be used to create slack area 10 a .", "The first set of rollers 102 a , 104 a , 106 a deform the laminate 10 to form a small slack area.", "The second set of rollers 102 b , 104 b , 106 b have a larger overlap and thus form a larger slack area.", "The third set of rollers 102 c , 104 c , 106 c are overlapped to form a slack area 10 a of the desired shape.", "[0035] A corrugator 120 , as seen in FIGS. 8 and 9 include a first support plate 122 having a female corrugator 124 and a second support plate 126 which includes male corrugator section 128 .", "The male 128 and female 124 corrugator sections have an increasing cross-sectional area along the length of the web and are nested to cause the laminate 10 to deform and thus create slack area 10 a. [0036] The laminate of the present invention may be achieved with the use of a wide variety of polymer films;", "however, in a preferred form the film is manufactured by first melt blending a composition of: [0037] (a) about 35% to about 45% by weight of a linear low density polyethylene, [0038] (b) about 3% to about 10% by weight of a low density polyethylene, [0039] (c) about 40% to about 50% by weight calcium carbonate filler particles, and [0040] (d) about 2% to about 6% by weight of a triblock copolymer of styrene selected from the group consisting of styrene-butadiene-styrene, styrene-isoprene-styrene, and styrene-ethylene-butylene-styrene, and blends thereof, [0041] extruding the melt blended composition into a nip of rollers with an air knife to form a film at a speed on the order of at least about 550 fpm to about 1200 fpm without draw resonance, and [0042] applying an incremental stretching force to the film along lines substantially uniformly across the taut areas of the laminate and throughout its depth to provide a microporous film.", "[0043] More particularly, in a preferred form, the melt-blended composition consists essentially of about 42% by weight LLDPE, about 4% by weight LDPE, about 44% by weight calcium carbonate filler particles having an average particle size of about 1 micron, and about 3% by weight triblock polymer, especially styrene-butadiene-styrene.", "If desired, the stiffness properties of the microporous film products may be controlled by including high density polyethylene on the order of about 0-5% by weight and including 0-4% by weight titanium dioxide.", "Typically, a processing aid such as a fluorocarbon polymer in an amount of about 0.1% to about 0.2% by weight is added, as exemplified by 1-propene, 1,1,2,3,3,3-hexafluoro copolymer with 1,1-difluoroethylene is included in the melt.", "The triblock polymer may also be blended with oil, hydrocarbon, antioxidant and stabilizer.", "[0044] Both embossed and flat films may be produced according to the principles of this invention.", "In the case of an embossed film, the nip of rollers comprises a metal embossing roller and a rubber roller.", "The compressive force between the rollers forms an embossed film of desired thickness on the order of about 0.5 to about 10 mils.", "It has also been found that rollers which provide a polished chrome surface form a flat film.", "Whether the film is an embossed film or a flat film, upon incremental stretching at high speeds, microporous film products are produced having high moisture vapor transmission rate (MVTR) within the acceptable range of about 1000 to 4000 gms/m 2 /day.", "It has been found that flat film can be incrementally stretched more uniformly than embossed film.", "The process may be conducted at ambient or room temperature or at elevated temperatures.", "As described above, laminates of the microporous film may be obtained with non-woven fibrous webs.", "[0045] The non-woven fibrous web may comprise fibers of polyethylene, polypropylene, polyesters, rayon, cellulose, nylon, and blends of such fibers.", "A number of definitions have been proposed for non-woven fibrous webs.", "The fibers are usually staple fibers or continuous filaments.", "The non-wovens are usually referred to as spunbond, carded, meltblown and the like.", "The fibers or filaments may be bicomponent to facilitate bonding.", "For example, a fiber having a sheath and core of different polymers such as polyethylene (PE) and polypropylene (PP) may be used or mixtures of PE and PP fibers may be used.", "As used herein “non-woven fibrous web”", "is used in its generic sense to define a generally planar structure that is relatively flat, flexible and porous, and is composed of staple fibers or continuous filaments.", "For a detailed description of non-wovens, see “Nonwoven Fabric Primer and Reference Sampler”", "by E. A. Vaughn, Association of the Non-woven Fabrics Industry, 3d Edition (1992).", "[0046] In a preferred form, the microporous laminate employs a film having a gauge or a thickness between about 0.25 and 10 mils and, depending upon use, the film thickness will vary and, most preferably, in disposable applications, is on the order of about 0.25 to 2 mils in thickness.", "The non-woven fibrous webs of the laminated sheet normally have a weight of about 5 gms/yd 2 to 75 gms/yd 2 , preferably about 20 to about 40 gms/yd 2 .", "The composite or laminate can be incrementally stretched in the cross-direction (CD) to form a CD stretched composite.", "Furthermore, CD stretching may be followed by stretching in the machine direction (MD) to form a composite which is stretched in both CD and MD directions.", "As indicated above, the microporous film or laminate may be used in many different applications such as baby diapers, baby training pants, catamenial pads and garments, and the like where moisture vapor and air transmission properties, as well as fluid barrier properties, are needed.", "[0047] The laminate is then incrementally stretched in the cross-direction (CD) or diagonally using the apparatus of the present invention to form a stretched laminate having unstretched regions along the length of the laminate.", "Furthermore, stretching according to the present invention may be followed by stretching in the machine direction (MD).", "[0048] A number of different stretchers and techniques may be employed to stretch the film or laminate of a non-woven fibrous web and microporous-formable film.", "These laminates of non-woven carded fibrous webs of staple fibers or non-woven spun-bonded fibrous webs may be stretched with the stretchers and techniques described as follows: [0049] The diagonal intermeshing stretcher consists of a pair of left hand and right hand helical gear-like elements on parallel shafts.", "The shafts are disposed between two machine side plates, the lower shaft being located in fixed bearings and the upper shaft being located in bearings in vertically slidable members.", "The slidable members are adjustable in the vertical direction by wedge shaped elements operable by adjusting screws.", "Screwing the wedges out or in will move the vertically slidable member respectively down or up to further engage or disengage the gear-like teeth of the upper intermeshing roll with the lower intermeshing roll.", "Micrometers mounted to the side frames are operable to indicate the depth of engagement of the teeth of the intermeshing roll.", "[0050] Air cylinders are employed to hold the slidable members in their lower engaged position firmly against the adjusting wedges to oppose the upward force exerted by the material being stretched.", "These cylinders may also be retracted to disengage the upper and lower intermeshing rolls from each other for purposes of threading material through the intermeshing equipment or in conjunction with a safety circuit which would open all the machine nip points when activated.", "[0051] A drive is typically utilized to drive the stationery intermeshing roller.", "If the upper intermeshing roller is to be disengagable for purposes of machine threading or safety, it is preferable to use an antibacklash gearing arrangement between the upper and lower intermeshing rollers to assure that upon reengagement the teeth of one intermeshing roller always falls between the teeth of the other intermeshing roller and potentially damaging physical contact between addenda of intermeshing teeth is avoided.", "If the intermeshing rollers are to remain in constant engagement, the upper intermeshing roll typically need not be driven.", "Drive may be accomplished by the driven intermeshing roller through the material being stretched.", "[0052] The intermeshing rollers closely resemble fine pitch helical gears.", "[0053] In the preferred embodiment, the rollers have 5.935″ diameter, 45° helix angle, a 0.100″ normal pitch, 30 diametral pitch, 14½° pressure angle, and are basically a long addendum topped gear.", "This produces a narrow, deep tooth profile which allows up to about 0.090″ of intermeshing engagement and about 0.005″ clearance on the sides of the tooth for material thickness.", "The teeth are not designed to transmit rotational torque and do not contact metal-to-metal in normal intermeshing stretching operation.", "With such a diagonal intermeshing stretcher, a presser disc 32 having the configuration of a helical gear would be used.", "The use of a diagonal intermeshing stretcher provides for a stretching force having force components in both the cross machine direction and the machine direction of the laminate.", "[0054] The drive for the CD intermeshing stretcher typically operates both upper and lower intermeshing rollers except in the case of intermeshing stretching of materials with a relatively high coefficient of friction.", "The drive need not be antibacklash, however, because a small amount of machine direction misalignment or drive slippage will cause no problem.", "[0055] The CD intermeshing elements are machined from solid material but can best be described as an alternating stack of two different diameter disks.", "In the preferred embodiment, the intermeshing disks would be 6″ in diameter, 0.031″ thick, and have a full radius on their edge.", "The spacer disks separating the intermeshing disks would be 5½″ in diameter and 0.069″ in thickness.", "Two rolls of this configuration would be able to be intermeshed up to 0.231″ leaving 0.019″ clearance for material on all sides.", "As with the diagonal intermeshing stretcher, this CD intermeshing element configuration would have a 0.100″ pitch.", "[0056] The MD intermeshing stretching equipment is identical to the diagonal intermeshing stretch except for the design of the intermeshing rollers.", "The MD intermeshing rolls closely resemble fine pitch spur gears.", "In the preferred embodiment, the rolls have a 5.933″ diameter, 0.100″ pitch, 30 Diametral pitch, 14½″ pressure angle, and are basically a long addendum, topped gear.", "A second pass was taken on these rolls with the gear hob offset 0.010″ to provide a narrowed tooth with more clearance.", "With about 0.090″ of engagement, this configuration will have about 0.010″ clearance on the sides for material thickness.", "[0057] The above described diagonal or CD intermeshing stretchers may be employed with the pin-hole prevention apparatus of the present invention to produce the incrementally stretched film or laminate of non-woven fibrous web and microporous-formable film to form the microporous film products of this invention.", "For example, the stretching operation may be employed on an extrusion laminate of a non-woven fibrous web of staple fibers or spun-bonded filaments and microporous-formable thermoplastic film.", "In one of the unique aspects of this invention, a laminate of a non-woven fibrous web of spun-bonded filaments may be incrementally stretched to provide a very soft fibrous finish to the laminate that looks like cloth.", "The laminate of non-woven fibrous web and microporous-formable film is incrementally stretched using, for instance, the CD and/or MD intermeshing stretcher with one pass through the stretcher with a depth of roller engagement at about 0.060 inch to 0.120 inch at speeds from about 550 fpm to 1200 fpm or faster.", "The results of such incremental or intermesh stretching produces laminates that have excellent breatheability and liquid-barrier properties, yet provide superior bond strengths and soft cloth-like textures.", "[0058] The microporous laminate typically employs a film having a gauge or a thickness between about 0.25 and 10 mils and, depending upon use, the film thickness will vary and, most preferably, in disposable applications is the order of about 0.25 to 2 mils in thickness.", "The non-woven fibrous webs of the laminated sheet normally have a weight of about 5 grams per square yard to 75 grams per square yard preferably about 20 to about 40 grams per square yard.", "[0059] The following examples illustrate the method of making microporous film and laminates of this invention.", "In light of these examples and this further detailed description, it is apparent to a person of ordinary skill in the art that variations thereof may be made without departing from the scope of this invention.", "EXAMPLES 1-5 [0060] Blends of LLDPE and LDPE having the compositions reported in the following TABLE 1 were extruded to form films and the films were then incrementally stretched to provide microporous films.", "TABLE 1 Formulation (by wt.) 1 2 3 4 5 CaCO 3 44.2 44.2 44.2 44.2 44.2 LLDPE 44.1 44.9 41.9 41.9 41.9 LDPE 1.5 3.7 3.7 3.7 3.7 Others* 10.2 10.2 10.2 10.2 10.2 Screw A 33 45 57 64 75 RPM B 33 45 57 64 75 Basis wt.", "(gms/m 2 ) 45 45 45 45 45 Gauge (mils) 2 2 2 2 2 Line Speed (fpm) 550 700 900 1000 1200 Air Knife (cfm/inch) 5-25 5-25 5-25 5-25 5-25 Web Stability Poor Good web stability without draw resonance gauge control with draw resonance [0061] Each of the formulations of 1-5 were extruded into films employing an extrusion apparatus.", "The formulations of Examples 1-5 were fed from an extruder through a slot die to form the extrudate into the nip of a rubber roll and a metal roll.", "The incoming webs of non-woven material were also introduced into the nip of the rolls.", "In Examples 1-5, the thermoplastic film was produced for subsequent incremental stretching to form the microporous film.", "As shown in TABLE 1, over speeds of about 550 fpm to 1200 fpm, a polyethylene film on the order of about 2 mils in thickness was made which is taken off the roller.", "The compressive force at the nip is controlled such that the film is made without pin-holing and without draw resonance in the case of Examples 2-5.", "The melt temperatures from the feed zone to the screw tip of extruders were maintained at about 400-430° F. with die temperatures of approximately 450° F. to extrude the precursor film around 2 mils (45 g/m 2 ).", "[0062] As shown in TABLE 1 , over speeds of about 550 fpm to 1200 fpm, a polyethylene film on the order of about 2 mils in thickness was made which is taken off the roller.", "The air knife has a length of about 120″ and an opening of about 0.035″-0.060″ and air is blown through the opening and against the extrudate at about 5 cfm/inch to 25 cfm/inch.", "The compressive force at the nip and the air knife are controlled such that the film is made without pin-holing and without draw resonance in the case of Examples 2-5.", "Where the LDPE was included in the composition at a level of 1.5% by weight, draw resonance was encountered at a line speed of 550 fpm.", "However, when the LDPE was included in the formulation at a level of 3.7% by weight with the LLDPE at a level of 44.1-44.9% by weight, film production was able to be achieved at high speeds greater than 550 fpm up to 1200 fpm without draw resonance.", "The melt temperatures from the feed zone to the screw tip of the extruders were maintained at about 400-430° F. with die temperatures of approximately 450° F. to extrude the precursor film around 2 mils (45 gms/m 2 ).", "[0063] [0063 ]FIG. 10 is a graph demonstrating the line speeds for Examples 1-5 and the necessary screw speed.", "Example 1 , which contained only 1.5% by weight of LDPE, resulted in a poor film gauge control with draw resonance even with the air knife.", "However, when the LDPE was increased to about 3.7% by weight, excellent web stability was achieved without draw resonance even when line speeds were increased to about 1200 fpm.", "[0064] [0064 ]FIG. 11 is a graph demonstrating the moisture vapor transmission properties (MVTR) of both embossed and flat films resulting from incrementally stretching the precursor films of Examples 2-5 under different temperatures and stretch roller engagement conditions.", "The MVTRs for the embossed film on the order of about 1200-2400 gms/m 2 /day were achieved, whereas MVTRs for the flat film on the order of about 1900-3200 gms/m 2 /day were achieved.", "FIG. 12 shows the impact of the temperature of the CD preheat roller upon MVTR.", "The MVTR for the film varied between about 2000-2900 gms/m 2 /day with the roller preheat temperature between about 75-220 F. The embossed film was made with a metal embossing roller having a rectangular engraving of CD and MD lines with about 165-300 lines per inch.", "This pattern is disclosed, for example, in U.S. Pat. No. 4,376,147 which is incorporated herein by reference.", "This micro pattern provides a matte finish to the film but is undetectable to the naked eye.", "[0065] Those skilled in the art will recognize that the exemplary embodiment illustrated in the drawings is not intended to limit the invention.", "Indeed, those skilled in the art will recognize that other alternative embodiments may be used without departing from the scope of the invention." ]
This is a continuation-in-part of application Ser. No. 08/999,372, filed Dec. 29, 1997, now abandoned, which was a continuation of application Ser. No. 08/480,581, filed Jun. 7, 1995, now abandoned. BACKGROUND OF THE INVENTION A. Field of the Invention The present invention relates to orthopedic support devices for minimizing spinal stress while an individual is in the lying position. More particularly the present invention relates to an orthopedic support device that bolsters, i.e., supports the back of the legs of an individual lying on his/her back and additionally maintains spinal support for an individual when lying on his/her side; and to adjustable orthopedic support pillows which can be varied and customized to support the individual's needs. B. Discussion of the Prior Art Spinal related complaints are very common. In fact, back pain is the second most common complaint (behind the common cold) for visits to the family doctor. Proper spinal support (whether related to the lower back, upper back or neck) has been a concern for decades. This has resulted in a significant variety of products designed to provide greater comfort and support. The majority of these products were designed for 95 percentile of the population. As all individuals vary anatomically, and when combining this factor with individual and personal preference, the varying possibilities would render customization to all individuals to be not practical. Methods of customization for both the cervical and lumbar spine have been attempted, as discussed below. However, these vary from intricate systems of support that are either adjustable through an inflatable means, fluid filled or even a combination of self attachment through the use of hook and loop fastening devices, zippers and strapping. All of these methods although effective, would be extremely costly from a manufacturing standpoint. None of these products, whether designed to support the cervical or lumbar spine, ever considered the specific needs of the individual user. For all of the above reasons, a need exists for an orthopedic support pillow that is capable of being customized to the individuals needs as opposed to the individual conforming to the product. The present invention overcomes many of the problems of the prior art in that it provides a capability for customization of an orthopedic support pillow to fit the individuals needs, without the use of accessory application devices such as hook and loop, elastic bands, zippers and/or straps. It is generally known that maintaining proper posture of the spine helps to prevent the occurrence of spinal injury and back pain. The preferred proper spinal posture in all daily sitting and upright activities includes a slight lordotic curve in the lumbar region of the spine, or what is known as the "neutral spine" position in lay terms. That is the spinal position where all stress on the spine is minimized to allow the spine to rest in its naturally curved position. For example, it is commonly known that when lifting heavy objects, an individual should use their knees to lift such objects and that the back should be maintained in the neutral spine position to alleviate any potential stress to the spine which can lead to back pain. With the recent, increasing interest in ergonomics and in prevention of repetitive trauma injuries in the work place, sleep ergonomics has been for the most part neglected. On the average of 1/3 of most individuals' lives is spent partaking in this form of activity. One must appreciate the necessity that merely lying down is not sufficient for spinal stress reduction and thus proper sleep postural maintenance is paramount for complete and comfortable rest. For years it has been recommended that proper sleep posture would entail avoiding the prone position, simply due to the aggravated stress on the lumbar spine (from accentuation of the lordotic curve) and as well the rotational positioning of the cervical spine could lead to neck pathomechanics over time. The supine position was promoted, however, without the appropriate flexion at the knee the lumbar lordotic curve was as well accentuated. In other words, when lying on the backside, it is natural for the legs to lie flat on the sleeping surface. In this manner the legs cooperate with the buttocks to act as a lever raising the lumbar region of the spine thereby causing an unnatural accentuation of the lordotic curve that may result in stress on the spine as well. In order to alleviate this stress caused by the legs, it is preferred that an individual sleep with the knees bent. This sleeping position reduces the stress on the lumbar region of the spine and allows the spine to rest flatly against the mattress or other sleeping surface. However, without some type of leg support, the natural tendency of the knees is to flatten out. Lying on one's side is another preferred sleep position. However, without the appropriate support, the lumbar spine has a tendency to be affected by rotational stresses due to torquing factors between the upper and lower body. In the side lying position, the legs of the individual are generally maintained in an overlying relationship with each other. Positioning the legs in this manner at the mattress along one side of the body causes the body to compensate for this position which may result in stress on the spine. In order to minimize these stresses one must be knowledgeable of both human anatomy as well as physical forces acting on the spine. Simply relieving gravitational stress from the spine is insufficient to reduce spinal stress and strain to the point of eliminating it. Several devices have been proposed to alleviate stress on the spine of an individual while sleeping. Such devices include large pillows or other supporting devices placed between the upper thighs of an individual to maintain a side lying position. These pillows extend out and away from the front and back sides of the individual to block, or prevent the individual from rolling over. Such devices are well known in the art and a variety of such pillows are available. One problem associated with these devices arises from the natural tendency of people to roll or shift positions while sleeping. Such movement can cause these pillows to shift or move from the preferred position in-between the individuals legs thereby defeating the purpose of the pillow or causing the sleeper to awaken and re-adjust the pillow. Some side lying devices have over come this problem by adding straps to secure the pillow to the thighs. However, it is not desirable to secure the pillow in this manner especially if a fire or other emergency occurred. Thus the need exists for an orthopedic support pillow that maintains support between the legs for a sleeper lying in a side lying position, but which can easily be removed. In addition, it is desirable to have an orthopedic device as described above that could also support the back sides of the legs to maintain a bend in the knees of an individual while lying in the supine position. Such a dual capability would allow an individual to select a comfortable sleeping position while helping to alleviate stress on the spine. Thus the need exists for an orthopedic device that relieves spinal stress and strain either when an individual is lying on his/her side or back, and provides for a selection of individual sleep positions. OBJECTS AND SUMMARY OF THE INVENTION A primary object of the present invention is provide a flexible lower limb support device which can be utilized in order to support and assist an individual to lying in either the supine or side lying positions. It is yet another object of the present invention to provide a flexible lower limb support device which will inhibit an individual from lying in the prone position. It is yet another object of the present invention to provide a flexible lower limb support device which can maintain the normal anatomical position of the lower limbs when side lying in order to minimize stress on the lumbar spine, sacroiliac joints and femoral acetabular joints. It is yet another object of the present invention to provide a flexible lower limb support device which will assist an individual lying supine by minimizing the lumbar lordotic curve. Another object of the present invention is to provide leg secure engagement of the device to the inner thighs of the individual for uninterrupted sleep while in a side lying position. These and other objects of the present invention are attained by providing lower limb support device which is, generally, biconcave in lengthwise design and consists of two outer layers of lower density polyurethane foam and a middle layer of higher density polyurethane foam. The opposing outer layers are contour cut to provide two widthwise channels traversing opposing upper and lower outer layers of the device. The channels, forming C-shaped clasps, universally contour and support an individual's thighs as well as the upper border of the knee joints by maintaining them in the normal anatomical position. Several of the embodiments described herein incorporate three forms of orthopedic support cushions which are utilized on different regions. All three of these pillows are customizable via a tongue and groove attachment where the individual components of the support cushion can be either added to or subtracted from other components create the customization desired and necessary for the individual user. The first alternate embodiment includes a cervical pillow, which is contoured by having two buttress of unequal dimension placed linearly at either end of the pillow. Vertically the pillow is made up three layers such that it's height can be customized to an individual physical and therapeutic needs. These layers are connected to one another via a tongue and groove locking mechanism which fastens the layers to one another in series. This tongue and groove mechanism consists of a (mushroom like) male projection and negative impression, female conduit. The male projection comprises of a head which is connected to a shaft. The diameter of the shaft is somewhat narrower (and is positioned axially to the head) than the diameter of the head resulting in the lateral borders of the head protruding symmetrically laterally. The female conduit is a negative impression of the male projection and is comprised of a head receiving area and stem receiving area. In application, large individuals (larger 10% of population) would require all three layers in position in order to provide support for the natural curvature of their cervical spine. The average individual (average height and weight) would only require two layers and at the smaller end of the scale, slight individuals would only require a single layer of support. These variances are broad spectrum, and additional consideration to choice of a specific number of layers would involve consideration of multiple other factors, e.g., whether the individual is predominantly a stomach or side sleeper, types of inherent deformity to the spinal curvature, and, most importantly the, individualized preference. BRIEF DESCRIPTION OF DRAWINGS Other objects and advantages of the invention will become apparent from the forgoing detailed description taken in connection with the accompanying drawings, in which: FIG. 1 is a perspective view of the side support pillow device of the present invention; FIG. 2 is a side view of the side support pillow having top and bottom leg clasps; FIG. 3 is a top view of the side support pillow; FIG. 4 is a perspective view of the side support pillow being used while an individual is in the side lying position with her thighs securely engaged within the respective clasps; FIG. 5 is a perspective view of the side support pillow being used while an individual is lying in the supine position; FIG. 6 is a front view of the side support pillow; and FIG. 7 is a side view of the side support pillow having top and bottom leg clasps forced apart for placement between the legs. FIG. 8 is a perspective, exploded view taken from the front and to the side of an alternate embodiment showing a three layered, tongue and groove support pillow embodiment of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawings for purposes of illustration, the invention is generally embodied in a foam pillow 20, shown in FIGS. 1-3, comprised of two outer cushioning layers 22 and 24 of resilient foam material joined along inner surfaces 23,25 respectively to opposite surfaces of a high density foam mat 26. The outer surface 28 of each cushioning layer, generally rectangular in shape, from a top view as shown in FIG. 3 includes a concave shaped surface (FIGS. 1 and 6) forming a valley 30 bounded by side walls 32 and 34 rounded at respective peaks extending lengthwise dimension "I", as shown in FIG. 1 along the respective sides 36 and 38 of the pillow. Included within each cushion layer 22,24 (FIGS. 1-3) traversing the lengthwise median on opposite sides of the inner mat are opposing C-shaped channels 40 and 42 extending in a widthwise dimension "w", as shown in FIG. 1, forming outwardly-facing, leg clasps. Thus, configured the pillow presents the appearance of two crescent-shaped buttresses 44 and 46, extending along the width wise dimension w and from top to bottom along a height dimension "h", as shown in FIG. 1 each formed with two outer convex surfaces 48A, 48B extending in a circular arc about an axis L1, L2 each of which extend through the inside of the pillow as shown in FIGS. 1 and 2. The C-shaped channels have four edges as shown at 56A, 56B, 56C, and 56D in FIGS. 1 and 2. Each of these four edges 56A, 56B, 56C and 56D are formed at the intersection of the two ends of the arcs of each of the two end surfaces 48A, 48B with the two ends of the arcs of each of the two channels 40, 42, at the ends of their inwardly facing surfaces 50A, 50B. The four edges 56A, 56B, 56C and 56D extend along the pillow in the width wise direction w, to form resilient fingers which perform a clasping function as described in greater detail below. A central stem 52, shown in FIG. 2 as lying within the region bounded by the dashed lines 53A, 53B and having convex-shaped ielliptical arcs of curvature as shown at 54A, 54B, connects between the two crescent shaped buttresses and form the two surfaces 50A, 50B. The pillow, thus formed, when standing end-to-end is bi-laterally symmetric about the lengthwise plane formed by the central mat 26. The C-shaped channels each have an elliptical cross-sectional shape with the major axis of each channel 55A, 55B being parallel to the lengthwise median. The channels extend across the pillow in the width direction w, with one channel open to the top in the height dimension and one channel open to the bottom, as shown in FIG. 1. As also shown in FIGS. 1 and 2, the arc of curvature of each of the C-shaped channels is greater than 180°, extends along the width dimension and appears to be like the letter "C" rotated 90° so that one channel, 40 is open upward, and the other, opposed channel 42 is open downward. Each of the outer surfaces 48A, 48B has a cross-sectional shape of that of a portion of a circle, with the center of each circle in the median and defining an axis of rotation L1, L2. The outer surfaces 48A, 48B also extend across the pillow in the width direction w, have an arc of curvature greater than 180°, so that the arc of curvature of end 48A is open toward the interior of the pillow, i.e., to the right as shown in FIGS. 1 and 2, and the arc of curvature of end 48B is open toward the interior of the pillow, i.e., to the left as shown in FIGS. 1 and 2. In FIG. 2, a plane tangent to the tops of arcs of curvature of ends 48A, 48B, respectively is shown at T1, and a plane tangent to the bottoms of arcs of curvature 48A, 48B, respectively is shown at T2. By being greater than 180°, the arcs of curvature of the ends 48A, 48B extend beyond the points of tangency at which planes T1 and T2 are tangent to the uppermost and lowermost part of the arcs of curvature of ends 48A and 48B, and provide the structure of the resilient fingers for clasping the thighs of the user. The central mat 26 provides a stiff center layer lengthwise through the center of the pillow 20, bounded on opposite sides by a comfortable outer layer 22 and 24 for contacting the legs of an individual. The foam pillow outer material 22 and 24 is preferably made from low density polyurethane foam of the type manufactured using conventional techniques for foam sleeping pillows. The inner layer or mat 26 is preferably made from high density polyurethane foam of the type manufactured using conventional techniques for foam gymnastic or camping floor mats. These layers may then be molded together using conventional glue or heat bonding techniques. In use, the pillow 20 of the preferred embodiment can be used to reduce spinal stress while in the side lying and supine sleeping positions. When used for the side lying sleeping position (FIG. 4), the inner thighs 55 of an individual are placed within the respective clasps 40 and 42 of the pillow. Each clasp 40 and 42 includes deformable, resilient lips 56 (FIG. 7) which when forced to spread apart, as illustrated by force lines 58, provide an opening for receipt of an individual's thigh 55. The lips 56, when released return to their original position in engagement thereby hugging the respective thigh in a secure, universally-contoured engagement. The low density foam material securely maintains the pillow 20 between the thighs 55 throughout the sleep period by resisting disengagement from tossing and turning by the individual without any discomfort due to the containment of the thighs within the respective clasps. Once in place (FIG. 4), the crescent shaped buttresses 44 and 46 extend out from the front and back sides of the individual respectively. The bulk of the buttresses 44 and 46 supported by the rigidity of the inner mat 26 are of sufficient size and rigidity to resist the desire of the sleeping individual to roll over onto the prone or supine positions. The stem 52, secured between the thighs and further supported by the rigid compression resistant mat 26, produces a gap between the thighs 55, thereby resisting the natural tendency of the upper knee 60 to lie on top of the lower knee 62. The gap between the knee, preferably 2-4 inches, relieves the torsional stress on the spine created by the undesired rotation of the upper leg. Thus, the pillow 20 used in the side lying position, not only prevents rotation by the individual into an undesirable prone position, but also reduces spinal stress while in the side lying position by displacing the upper knee 60 in spaced apart relation to the lower knee 62. Similarly, when used for sleeping in the prone position (FIG. 5), the individual's legs extend traversely widthwise across one of the concave outer surfaces 30 of the pillow. The bulk of the pillow further enhanced by the compression resistant mat 26 causes the knees 60 and 62 to bend at an obtuse angle to accommodate the pillow 20 there under. With the knees bent, the lordotic curve of the spine is reduced or eliminated thereby allowing the lower spine to rest against the mattress or sleeping surface 64. Once again the outer layers 22 and 24 of the pillow compress and universally contour fit the shape of the individual's legs and underlying sleeping surface. Although compressed, the pillow does not uniformly support the back sides of the legs. Instead, the side walls 32 and 34 (FIGS. 5 and 6), created by the concave upper and lower surfaces having a stylized H-shape when viewed from an end, compress to a greater thickness than the middle valley portions 30 of the upper and lower surfaces 28. This non-uniform distribution of compression, ensures that bolstered knee is supported mainly by the backsides of the thigh 55 and calf 66. This reduces any direct pressure against the back of the knees 60 and 62 which is undesirable. Thus, the pillow 20 when used in the supine position reduces spinal stress by flattening out the spine, while supporting the knees 60 and 62 by the preferred backsides of the thigh 55 and calf 66 regions. With reference to FIG. 8, an alternate embodiment illustrates an effective and preferred structure and method of customization for a between-the-knee support device 80 which solves the problem of variation between various sizes and personal choice of individuals. Ideally the body should rest in the natural anatomical position. The natural anatomical position as defined and pertaining to the lower limb is identified with the medial malleoli (ankles) separated by 7 inches and the medial condyles of the knees (inner border of the knee joint) separated by 4 inches. Variations from this norm creates abnormal strain on the femoral acetabular joint and the sacroiliac joints respectively. The pillow of the present invention should be used in the side lying position where an individual can adjust the distance between opposing knees by either varying the thickness or density of the "stem" 82 thus maintaining the normal anatomical position. The diameter of the leg clasps should stay constant despite varying the diameter of the stem. Increasing the diameter of the stem (for larger individuals) would also necessitate increasing the general height of the bumpers 84 in order provide enough rotational support to prevent the individual from rolling into the prone position while sleeping. This alteration in diameter of height of both the stem 82 and bumpers 84 can be attained by either adding or removing part of the material making up the product. This would allow the general shape of the product to maintained however the size (more specifically the height) would become variable. This would maintain the functionality of the product and yet allow customization for the individuals needs. Adding and removing material to alter the general height of the product can be easiest attained by creating segments or layers, one of which is shown at 86. These layers whether added or removed would completely functional as different entities. Therefore the product is divided into two components. The upper and lower body contact regions and the functional components 88 and 90, respectively ("FC") and removable layers are the adjustable components ("AC") one of which is shown at 86. An important feature is that the functional components 88, 90 act as solitary components regardless of the activity of the adjustable component(s) 86. Thus the FC 88, 90 must be connected by some structure, either directly or indirectly (interrupted by the AC) to the opposing FC. Various structures for creating this adhesion may be used, e.g., Velcro (hook and loop) fasteners, strapping, webbing and/or elastic fasteners. The preferred structure and method would employ the structure of the FC and AC so that they would connect to one another in series whether the AC is engaged or disengaged. This preferred connection can be attained by providing either a singular or plurality of male projections and female conduits which would fasten the two FC's together, whether the FC's were either connected to one another directly, or indirectly connected through one or more of the AC's 86, thus allowing assembled support pillow to function as a solitary unit. By connecting these components through a series of male projections and female layer 86, a high degree of customization is made possible with minimum additional structure and minimum to no loss of structural integrity of the pillow. It is emphasized that the AC 86 can vary in number, as well as thickness of each layer 86. The principles of the present invention can also be used to provide various additional components to the cushion, e.g., different sized bumpers, various sizes for the leg clasps and so forth. It will be appreciated by those skilled in the art, that a variety of sizes will be available to accommodate the diverse range of human forms. Such sizes will need to consider the size of the buttress in relation to the size and weight of the individual. In addition, the size of the leg clasps will need to adjust to variances in thigh diameter. While the present invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but to the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit of the invention, which are set forth in the appended claims, and which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures.
A stress reducing device is defined by a dual use orthopedic pillow having a low density polyurethane foam outer region, a high density polyurethane foam middle region that are provided in removably attachable layers, so that the size of the device may be adjusted to accommodate different sizes and preferences of individual users. The pillow advantageously includes leg clasps for securely engaging the inner thighs of an individual in a sideling position defined by a stem and a pair of crescent shaped buttresses. The buttresses resist rotation to the prone and supine lying positions. The high foam within the stem separates the knees to reduce spinal stress. Advantageously, a supine sleeping position is added by positioning said pillow under the legs to flatten out the spine while supporting the legs at the thigh and calf regions.
Summarize the key points of the given document.
[ "This is a continuation-in-part of application Ser.", "No. 08/999,372, filed Dec. 29, 1997, now abandoned, which was a continuation of application Ser.", "No. 08/480,581, filed Jun. 7, 1995, now abandoned.", "BACKGROUND OF THE INVENTION A. Field of the Invention The present invention relates to orthopedic support devices for minimizing spinal stress while an individual is in the lying position.", "More particularly the present invention relates to an orthopedic support device that bolsters, i.e., supports the back of the legs of an individual lying on his/her back and additionally maintains spinal support for an individual when lying on his/her side;", "and to adjustable orthopedic support pillows which can be varied and customized to support the individual's needs.", "B. Discussion of the Prior Art Spinal related complaints are very common.", "In fact, back pain is the second most common complaint (behind the common cold) for visits to the family doctor.", "Proper spinal support (whether related to the lower back, upper back or neck) has been a concern for decades.", "This has resulted in a significant variety of products designed to provide greater comfort and support.", "The majority of these products were designed for 95 percentile of the population.", "As all individuals vary anatomically, and when combining this factor with individual and personal preference, the varying possibilities would render customization to all individuals to be not practical.", "Methods of customization for both the cervical and lumbar spine have been attempted, as discussed below.", "However, these vary from intricate systems of support that are either adjustable through an inflatable means, fluid filled or even a combination of self attachment through the use of hook and loop fastening devices, zippers and strapping.", "All of these methods although effective, would be extremely costly from a manufacturing standpoint.", "None of these products, whether designed to support the cervical or lumbar spine, ever considered the specific needs of the individual user.", "For all of the above reasons, a need exists for an orthopedic support pillow that is capable of being customized to the individuals needs as opposed to the individual conforming to the product.", "The present invention overcomes many of the problems of the prior art in that it provides a capability for customization of an orthopedic support pillow to fit the individuals needs, without the use of accessory application devices such as hook and loop, elastic bands, zippers and/or straps.", "It is generally known that maintaining proper posture of the spine helps to prevent the occurrence of spinal injury and back pain.", "The preferred proper spinal posture in all daily sitting and upright activities includes a slight lordotic curve in the lumbar region of the spine, or what is known as the "neutral spine"", "position in lay terms.", "That is the spinal position where all stress on the spine is minimized to allow the spine to rest in its naturally curved position.", "For example, it is commonly known that when lifting heavy objects, an individual should use their knees to lift such objects and that the back should be maintained in the neutral spine position to alleviate any potential stress to the spine which can lead to back pain.", "With the recent, increasing interest in ergonomics and in prevention of repetitive trauma injuries in the work place, sleep ergonomics has been for the most part neglected.", "On the average of 1/3 of most individuals'", "lives is spent partaking in this form of activity.", "One must appreciate the necessity that merely lying down is not sufficient for spinal stress reduction and thus proper sleep postural maintenance is paramount for complete and comfortable rest.", "For years it has been recommended that proper sleep posture would entail avoiding the prone position, simply due to the aggravated stress on the lumbar spine (from accentuation of the lordotic curve) and as well the rotational positioning of the cervical spine could lead to neck pathomechanics over time.", "The supine position was promoted, however, without the appropriate flexion at the knee the lumbar lordotic curve was as well accentuated.", "In other words, when lying on the backside, it is natural for the legs to lie flat on the sleeping surface.", "In this manner the legs cooperate with the buttocks to act as a lever raising the lumbar region of the spine thereby causing an unnatural accentuation of the lordotic curve that may result in stress on the spine as well.", "In order to alleviate this stress caused by the legs, it is preferred that an individual sleep with the knees bent.", "This sleeping position reduces the stress on the lumbar region of the spine and allows the spine to rest flatly against the mattress or other sleeping surface.", "However, without some type of leg support, the natural tendency of the knees is to flatten out.", "Lying on one's side is another preferred sleep position.", "However, without the appropriate support, the lumbar spine has a tendency to be affected by rotational stresses due to torquing factors between the upper and lower body.", "In the side lying position, the legs of the individual are generally maintained in an overlying relationship with each other.", "Positioning the legs in this manner at the mattress along one side of the body causes the body to compensate for this position which may result in stress on the spine.", "In order to minimize these stresses one must be knowledgeable of both human anatomy as well as physical forces acting on the spine.", "Simply relieving gravitational stress from the spine is insufficient to reduce spinal stress and strain to the point of eliminating it.", "Several devices have been proposed to alleviate stress on the spine of an individual while sleeping.", "Such devices include large pillows or other supporting devices placed between the upper thighs of an individual to maintain a side lying position.", "These pillows extend out and away from the front and back sides of the individual to block, or prevent the individual from rolling over.", "Such devices are well known in the art and a variety of such pillows are available.", "One problem associated with these devices arises from the natural tendency of people to roll or shift positions while sleeping.", "Such movement can cause these pillows to shift or move from the preferred position in-between the individuals legs thereby defeating the purpose of the pillow or causing the sleeper to awaken and re-adjust the pillow.", "Some side lying devices have over come this problem by adding straps to secure the pillow to the thighs.", "However, it is not desirable to secure the pillow in this manner especially if a fire or other emergency occurred.", "Thus the need exists for an orthopedic support pillow that maintains support between the legs for a sleeper lying in a side lying position, but which can easily be removed.", "In addition, it is desirable to have an orthopedic device as described above that could also support the back sides of the legs to maintain a bend in the knees of an individual while lying in the supine position.", "Such a dual capability would allow an individual to select a comfortable sleeping position while helping to alleviate stress on the spine.", "Thus the need exists for an orthopedic device that relieves spinal stress and strain either when an individual is lying on his/her side or back, and provides for a selection of individual sleep positions.", "OBJECTS AND SUMMARY OF THE INVENTION A primary object of the present invention is provide a flexible lower limb support device which can be utilized in order to support and assist an individual to lying in either the supine or side lying positions.", "It is yet another object of the present invention to provide a flexible lower limb support device which will inhibit an individual from lying in the prone position.", "It is yet another object of the present invention to provide a flexible lower limb support device which can maintain the normal anatomical position of the lower limbs when side lying in order to minimize stress on the lumbar spine, sacroiliac joints and femoral acetabular joints.", "It is yet another object of the present invention to provide a flexible lower limb support device which will assist an individual lying supine by minimizing the lumbar lordotic curve.", "Another object of the present invention is to provide leg secure engagement of the device to the inner thighs of the individual for uninterrupted sleep while in a side lying position.", "These and other objects of the present invention are attained by providing lower limb support device which is, generally, biconcave in lengthwise design and consists of two outer layers of lower density polyurethane foam and a middle layer of higher density polyurethane foam.", "The opposing outer layers are contour cut to provide two widthwise channels traversing opposing upper and lower outer layers of the device.", "The channels, forming C-shaped clasps, universally contour and support an individual's thighs as well as the upper border of the knee joints by maintaining them in the normal anatomical position.", "Several of the embodiments described herein incorporate three forms of orthopedic support cushions which are utilized on different regions.", "All three of these pillows are customizable via a tongue and groove attachment where the individual components of the support cushion can be either added to or subtracted from other components create the customization desired and necessary for the individual user.", "The first alternate embodiment includes a cervical pillow, which is contoured by having two buttress of unequal dimension placed linearly at either end of the pillow.", "Vertically the pillow is made up three layers such that it's height can be customized to an individual physical and therapeutic needs.", "These layers are connected to one another via a tongue and groove locking mechanism which fastens the layers to one another in series.", "This tongue and groove mechanism consists of a (mushroom like) male projection and negative impression, female conduit.", "The male projection comprises of a head which is connected to a shaft.", "The diameter of the shaft is somewhat narrower (and is positioned axially to the head) than the diameter of the head resulting in the lateral borders of the head protruding symmetrically laterally.", "The female conduit is a negative impression of the male projection and is comprised of a head receiving area and stem receiving area.", "In application, large individuals (larger 10% of population) would require all three layers in position in order to provide support for the natural curvature of their cervical spine.", "The average individual (average height and weight) would only require two layers and at the smaller end of the scale, slight individuals would only require a single layer of support.", "These variances are broad spectrum, and additional consideration to choice of a specific number of layers would involve consideration of multiple other factors, e.g., whether the individual is predominantly a stomach or side sleeper, types of inherent deformity to the spinal curvature, and, most importantly the, individualized preference.", "BRIEF DESCRIPTION OF DRAWINGS Other objects and advantages of the invention will become apparent from the forgoing detailed description taken in connection with the accompanying drawings, in which: FIG. 1 is a perspective view of the side support pillow device of the present invention;", "FIG. 2 is a side view of the side support pillow having top and bottom leg clasps;", "FIG. 3 is a top view of the side support pillow;", "FIG. 4 is a perspective view of the side support pillow being used while an individual is in the side lying position with her thighs securely engaged within the respective clasps;", "FIG. 5 is a perspective view of the side support pillow being used while an individual is lying in the supine position;", "FIG. 6 is a front view of the side support pillow;", "and FIG. 7 is a side view of the side support pillow having top and bottom leg clasps forced apart for placement between the legs.", "FIG. 8 is a perspective, exploded view taken from the front and to the side of an alternate embodiment showing a three layered, tongue and groove support pillow embodiment of the present invention.", "DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawings for purposes of illustration, the invention is generally embodied in a foam pillow 20, shown in FIGS. 1-3, comprised of two outer cushioning layers 22 and 24 of resilient foam material joined along inner surfaces 23,25 respectively to opposite surfaces of a high density foam mat 26.", "The outer surface 28 of each cushioning layer, generally rectangular in shape, from a top view as shown in FIG. 3 includes a concave shaped surface (FIGS.", "1 and 6) forming a valley 30 bounded by side walls 32 and 34 rounded at respective peaks extending lengthwise dimension "I", as shown in FIG. 1 along the respective sides 36 and 38 of the pillow.", "Included within each cushion layer 22,24 (FIGS.", "1-3) traversing the lengthwise median on opposite sides of the inner mat are opposing C-shaped channels 40 and 42 extending in a widthwise dimension "w", as shown in FIG. 1, forming outwardly-facing, leg clasps.", "Thus, configured the pillow presents the appearance of two crescent-shaped buttresses 44 and 46, extending along the width wise dimension w and from top to bottom along a height dimension "h", as shown in FIG. 1 each formed with two outer convex surfaces 48A, 48B extending in a circular arc about an axis L1, L2 each of which extend through the inside of the pillow as shown in FIGS. 1 and 2.", "The C-shaped channels have four edges as shown at 56A, 56B, 56C, and 56D in FIGS. 1 and 2.", "Each of these four edges 56A, 56B, 56C and 56D are formed at the intersection of the two ends of the arcs of each of the two end surfaces 48A, 48B with the two ends of the arcs of each of the two channels 40, 42, at the ends of their inwardly facing surfaces 50A, 50B.", "The four edges 56A, 56B, 56C and 56D extend along the pillow in the width wise direction w, to form resilient fingers which perform a clasping function as described in greater detail below.", "A central stem 52, shown in FIG. 2 as lying within the region bounded by the dashed lines 53A, 53B and having convex-shaped ielliptical arcs of curvature as shown at 54A, 54B, connects between the two crescent shaped buttresses and form the two surfaces 50A, 50B.", "The pillow, thus formed, when standing end-to-end is bi-laterally symmetric about the lengthwise plane formed by the central mat 26.", "The C-shaped channels each have an elliptical cross-sectional shape with the major axis of each channel 55A, 55B being parallel to the lengthwise median.", "The channels extend across the pillow in the width direction w, with one channel open to the top in the height dimension and one channel open to the bottom, as shown in FIG. 1. As also shown in FIGS. 1 and 2, the arc of curvature of each of the C-shaped channels is greater than 180°, extends along the width dimension and appears to be like the letter "C"", "rotated 90° so that one channel, 40 is open upward, and the other, opposed channel 42 is open downward.", "Each of the outer surfaces 48A, 48B has a cross-sectional shape of that of a portion of a circle, with the center of each circle in the median and defining an axis of rotation L1, L2.", "The outer surfaces 48A, 48B also extend across the pillow in the width direction w, have an arc of curvature greater than 180°, so that the arc of curvature of end 48A is open toward the interior of the pillow, i.e., to the right as shown in FIGS. 1 and 2, and the arc of curvature of end 48B is open toward the interior of the pillow, i.e., to the left as shown in FIGS. 1 and 2.", "In FIG. 2, a plane tangent to the tops of arcs of curvature of ends 48A, 48B, respectively is shown at T1, and a plane tangent to the bottoms of arcs of curvature 48A, 48B, respectively is shown at T2.", "By being greater than 180°, the arcs of curvature of the ends 48A, 48B extend beyond the points of tangency at which planes T1 and T2 are tangent to the uppermost and lowermost part of the arcs of curvature of ends 48A and 48B, and provide the structure of the resilient fingers for clasping the thighs of the user.", "The central mat 26 provides a stiff center layer lengthwise through the center of the pillow 20, bounded on opposite sides by a comfortable outer layer 22 and 24 for contacting the legs of an individual.", "The foam pillow outer material 22 and 24 is preferably made from low density polyurethane foam of the type manufactured using conventional techniques for foam sleeping pillows.", "The inner layer or mat 26 is preferably made from high density polyurethane foam of the type manufactured using conventional techniques for foam gymnastic or camping floor mats.", "These layers may then be molded together using conventional glue or heat bonding techniques.", "In use, the pillow 20 of the preferred embodiment can be used to reduce spinal stress while in the side lying and supine sleeping positions.", "When used for the side lying sleeping position (FIG.", "4), the inner thighs 55 of an individual are placed within the respective clasps 40 and 42 of the pillow.", "Each clasp 40 and 42 includes deformable, resilient lips 56 (FIG.", "7) which when forced to spread apart, as illustrated by force lines 58, provide an opening for receipt of an individual's thigh 55.", "The lips 56, when released return to their original position in engagement thereby hugging the respective thigh in a secure, universally-contoured engagement.", "The low density foam material securely maintains the pillow 20 between the thighs 55 throughout the sleep period by resisting disengagement from tossing and turning by the individual without any discomfort due to the containment of the thighs within the respective clasps.", "Once in place (FIG.", "4), the crescent shaped buttresses 44 and 46 extend out from the front and back sides of the individual respectively.", "The bulk of the buttresses 44 and 46 supported by the rigidity of the inner mat 26 are of sufficient size and rigidity to resist the desire of the sleeping individual to roll over onto the prone or supine positions.", "The stem 52, secured between the thighs and further supported by the rigid compression resistant mat 26, produces a gap between the thighs 55, thereby resisting the natural tendency of the upper knee 60 to lie on top of the lower knee 62.", "The gap between the knee, preferably 2-4 inches, relieves the torsional stress on the spine created by the undesired rotation of the upper leg.", "Thus, the pillow 20 used in the side lying position, not only prevents rotation by the individual into an undesirable prone position, but also reduces spinal stress while in the side lying position by displacing the upper knee 60 in spaced apart relation to the lower knee 62.", "Similarly, when used for sleeping in the prone position (FIG.", "5), the individual's legs extend traversely widthwise across one of the concave outer surfaces 30 of the pillow.", "The bulk of the pillow further enhanced by the compression resistant mat 26 causes the knees 60 and 62 to bend at an obtuse angle to accommodate the pillow 20 there under.", "With the knees bent, the lordotic curve of the spine is reduced or eliminated thereby allowing the lower spine to rest against the mattress or sleeping surface 64.", "Once again the outer layers 22 and 24 of the pillow compress and universally contour fit the shape of the individual's legs and underlying sleeping surface.", "Although compressed, the pillow does not uniformly support the back sides of the legs.", "Instead, the side walls 32 and 34 (FIGS.", "5 and 6), created by the concave upper and lower surfaces having a stylized H-shape when viewed from an end, compress to a greater thickness than the middle valley portions 30 of the upper and lower surfaces 28.", "This non-uniform distribution of compression, ensures that bolstered knee is supported mainly by the backsides of the thigh 55 and calf 66.", "This reduces any direct pressure against the back of the knees 60 and 62 which is undesirable.", "Thus, the pillow 20 when used in the supine position reduces spinal stress by flattening out the spine, while supporting the knees 60 and 62 by the preferred backsides of the thigh 55 and calf 66 regions.", "With reference to FIG. 8, an alternate embodiment illustrates an effective and preferred structure and method of customization for a between-the-knee support device 80 which solves the problem of variation between various sizes and personal choice of individuals.", "Ideally the body should rest in the natural anatomical position.", "The natural anatomical position as defined and pertaining to the lower limb is identified with the medial malleoli (ankles) separated by 7 inches and the medial condyles of the knees (inner border of the knee joint) separated by 4 inches.", "Variations from this norm creates abnormal strain on the femoral acetabular joint and the sacroiliac joints respectively.", "The pillow of the present invention should be used in the side lying position where an individual can adjust the distance between opposing knees by either varying the thickness or density of the "stem"", "82 thus maintaining the normal anatomical position.", "The diameter of the leg clasps should stay constant despite varying the diameter of the stem.", "Increasing the diameter of the stem (for larger individuals) would also necessitate increasing the general height of the bumpers 84 in order provide enough rotational support to prevent the individual from rolling into the prone position while sleeping.", "This alteration in diameter of height of both the stem 82 and bumpers 84 can be attained by either adding or removing part of the material making up the product.", "This would allow the general shape of the product to maintained however the size (more specifically the height) would become variable.", "This would maintain the functionality of the product and yet allow customization for the individuals needs.", "Adding and removing material to alter the general height of the product can be easiest attained by creating segments or layers, one of which is shown at 86.", "These layers whether added or removed would completely functional as different entities.", "Therefore the product is divided into two components.", "The upper and lower body contact regions and the functional components 88 and 90, respectively ("FC") and removable layers are the adjustable components ("AC") one of which is shown at 86.", "An important feature is that the functional components 88, 90 act as solitary components regardless of the activity of the adjustable component(s) 86.", "Thus the FC 88, 90 must be connected by some structure, either directly or indirectly (interrupted by the AC) to the opposing FC.", "Various structures for creating this adhesion may be used, e.g., Velcro (hook and loop) fasteners, strapping, webbing and/or elastic fasteners.", "The preferred structure and method would employ the structure of the FC and AC so that they would connect to one another in series whether the AC is engaged or disengaged.", "This preferred connection can be attained by providing either a singular or plurality of male projections and female conduits which would fasten the two FC's together, whether the FC's were either connected to one another directly, or indirectly connected through one or more of the AC's 86, thus allowing assembled support pillow to function as a solitary unit.", "By connecting these components through a series of male projections and female layer 86, a high degree of customization is made possible with minimum additional structure and minimum to no loss of structural integrity of the pillow.", "It is emphasized that the AC 86 can vary in number, as well as thickness of each layer 86.", "The principles of the present invention can also be used to provide various additional components to the cushion, e.g., different sized bumpers, various sizes for the leg clasps and so forth.", "It will be appreciated by those skilled in the art, that a variety of sizes will be available to accommodate the diverse range of human forms.", "Such sizes will need to consider the size of the buttress in relation to the size and weight of the individual.", "In addition, the size of the leg clasps will need to adjust to variances in thigh diameter.", "While the present invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but to the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit of the invention, which are set forth in the appended claims, and which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures." ]
CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation, of application Ser. No. 07/647,937, filed Jan. 30, 1991 now abandoned, which is a division of application Ser. No. 07/506,729, filed Apr. 9, 1990 now U.S. Pat. No. 5,182,420, which is a continuation-in-part of application Ser. No. 07/343,506 filed Apr. 25, 1989, now abandoned, which application is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to chip carriers for high-density integrated circuits (ICs). In particular, it is directed to metallized chip carriers fabricated from wafer-shaped substrates. 2. Description of Related Art As integrated circuits become more dense, often containing hundreds of I/O connections, prior art techniques of packaging become less suitable. Packaging is considered by many in the industry to be the pacing technology for integrated circuit development. Many designers have recognized the need for developing new techniques for defining high-resolution traces on chip carriers. Up until the present invention, however, creating the required high-resolution traces presented significant manufacturing problems. In the prior art, chip carriers are fabricated using substrates onto which metallized traces are placed to provide electrical connections from the periphery of the substrate to the integrated circuit packaged within. These traces are typically manufactured using thick-film technology. The need to provide increasing numbers of connections has resulted in thin-film technology being used as a partial solution to bring the traces from the integrated circuit to pins on the carrier. Prior art thin-film technology brings traces from the IC to vias within the carrier, and the vias provide connections to the pins. A primary shortcoming in the prior art is that thin-film technology can not be reliably used to bring the traces from the IC within the carrier to the periphery of the carrier. Thus, there is a need in the art for high-density interconnects on chip carriers, which can provide traces directly from the integrated circuit packaged within the carrier to the periphery of the carrier, fabricated entirely with thin-film techniques. This shortcoming of the prior art requires that vias be used to connect traces to pin connections, making the overall footprint of the carrier larger than desirable. There is also a need in the prior art to manufacture chip carriers in quantity using thin-film technology, such that a high yield rate is attained with traces as narrow as 5 mils or less. SUMMARY OF THE INVENTION To overcome limitations in the prior art described above and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention uses wafer-shaped substrates and thin-film manufacturing techniques to create high-density traces on chip carriers for direct connections from the IC to the periphery without the need of vias. One object of the present invention is to provide a method for manufacturing metallized chip carriers from substrates shaped similarly to semiconductor wafers. Wafer-shaped substrates permit the use of standard semiconductor fabrication apparatus and methods. As a result, very thin and finely dimensioned traces can be deposited simultaneously on a plurality of chip carriers. DESCRIPTION OF THE DRAWINGS In the drawings, where like numerals refer to like elements throughout the several views, FIG. 1 is a top view of a wafer used in creating the chip carrier of the present invention. FIG. 2 is a cross-sectional side view of a portion of the ceramic wafer taken along lines 2--2 of FIG. 1. FIG. 3A is an individual chip carrier fabricated from the ceramic wafer and the trace pattern thereon. FIG. 3B is a magnified view of the trace pattern along one edge of the chip carrier taken along the dotted lines of FIG. 3A. FIG. 4 is a cross-sectional side view of a trace on the chip carrier of FIG. 3A and FIG. 3B. FIG. 5 is a top view of the lid for the ceramic carrier. FIG. 6 is a cross-sectional side view of the lid of FIG. 5. FIG. 7 is a top view of a wafer as fabricated in a second preferred embodiment of the present invention. FIG. 8 is a top view of a wafer as fabricated in a third preferred embodiment of the present invention. FIG. 9 is a top view of a wafer as fabricated in a fourth preferred embodiment of the present invention. FIG. 10 is a top view of a wafer as fabricated in a fifth preferred embodiment of the present invention. FIG. 11 is a cross-sectional side view of a trace on the chip carrier of FIG. 3A and FIG. 3B including a first alternate barrier metallurgy. FIG. 12 is a cross-sectional side view of a trace on the chip carrier of FIG. 3A and FIG. 3B including a second alternate barrier metallurgy. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration four specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. The present invention describes metallized chip carriers for high-density ICs and the steps required to fabricate these carriers. The preferred embodiment of the present invention uses thin-film techniques to deposit a large number of finely dimensioned traces on the surface of a substrate. Central to this invention is the use of standard semiconductor processing apparatus and methods in the fabrication of the chip carriers. First Preferred Embodiment Referring initially to FIG. 1, a substrate in a first preferred embodiment is shaped into a wafer 10. The substrate may be ceramic, such as aluminum oxide, aluminum nitrate, beryllium oxide, etc., or silicon. This wafer 10 is circularly shaped and keyed substantially similar to semiconductor wafers, which permits the use of IC fabrication apparatus and methods. The flat portion or key 8 of the wafer 10 is a reference key, ensuring the proper orientation of the wafer 10 during fabrication. Each wafer 10 is comprised of an array of cavities 14. In the first preferred embodiment, the wafer 10 contains 21 cavities 14. Thus, a plurality of chip carriers, generally identified by reference number 12, can be fabricated simultaneously. Each cavity 14 is substantially square and measures 0.426 inches in length (±0.003 inches) on each side. These cavities 14 will eventually contain an IC chip. The top surface of the IC is approximately planar with the top surface of the chip carrier 12. FIG. 2 is a cross-sectional side view of wafer 10. The wafer 10 is 0.060 inches (+0.002/-0.001 inches) thick. Each cavity 14 is recessed within the wafer 10 to a depth of 0.030 inches (±0.002 inches). If the substrate is ceramic, then the cavities may be fabricated by molding or other techniques known in the ceramic arts. For example, ceramic may be molded, milled, etc. Anvil and slurry milling will provide tighter tolerances than molding. When milled, the cavities are typically added after metallization, thereby avoiding problems with shrinkage of the cavities due to the sintering after punching or pressing the cavities. If the substrate is comprised of silicon, then the cavities may be fabricated by etching or other techniques known in the silicon arts. The cavities can be etched in the silicon substrate as the first step in production or at any other step along the way, provided that the patterning material will sufficiently protect any metallization currently on the package. For example, if the cavities are etched in silicon after aluminum, titanium, platinum, and gold metallization layers have been deposited, the masking material must be able to sufficiently protect these metals with their large dimensions. An advantage of using silicon is the ability to use silicon's electrical properties for a substrate voltage bias, buried resistors, etc. FIG. 3A shows a top view of a finished carrier 12 fabricated from the wafer 10. FIG. 3B shows a magnified view of the trace pattern along one edge of the carrier 12 taken along the dotted lines of FIG. 3A. The carrier 12 contains 90 traces per side (360 traces total), generally identified by reference number 16. The traces 16 are comprised of a plurality of metals. Using a plurality of metals in the trace 16 enhances bonding by allowing the trace 16 to metallically match both the bonding pads on the IC and the traces on the printed circuit board. FIG. 4 is a magnified, cross-sectional side view of an individual trace 16 that better illustrates the barrier metallurgy 20. The aluminum portion 22 is created first, the barrier metallurgy 20 is added on top of the aluminum, and finally, the gold portion 18 is added atop the barrier metallurgy 20. FIGS. 11 and 12 illustrate individual traces fabricated with alternate barrier metallurgies. Each metal is homogeneous for its portion of the trace 16. The inner length of each trace 16, generally identified by reference number 122 is preferably comprised of aluminum (Al). The outer length of each trace 16, generally identified by reference number 18, is preferably comprised of gold (Au). At the point where the inner length 22 meets the outer length 18, denoted by the dotted line 20 in FIG. 3, a barrier metallurgy is used. The barrier metallurgy 20 prevents the aluminum and gold from intermixing and forming "purple plague" and Kirkendall voiding. If Kirkendall voiding occurs, then the trace 16 could form an intermittent open due to localized heating from the electrical current, differences in expansion coefficients, and poor bond integrity. Those skilled in the art will readily recognize that other barrier metals could be used in the barrier metallurgy 20, depending upon a number of fabrication factors. For example, in a low temperature environment, titanium tungsten (TiW) or titanium under platinum could be used as shown in FIG. 11. At high temperatures, different combinations may be desired to improve adhesion and prevent diffusion of the metals. The rate of diffusion is at least partially determined by the temperature of the substrate. For example, nickel over chrome, platinum over titanium nitride over titanium (see FIG. 12), platinum over titanium tungsten over titanium or platinum over titanium tungsten nitride over titanium. Those skilled in the art will recognize that other metals such as palladium may be substituted for platinum to form the barrier metallurgy. Aluminum is used for the inner portion 22 of the traces 16 because the electrical interconnections to the IC are aluminum. Thus, using aluminum for the inner portion 22 of the traces 16 prevents bonding problems between the IC and the chip carrier 12. Gold is used for the outer portion 18 of the traces 16 because the electrical interconnections to the printed circuit board are gold. Thus, using gold for the outer portions 18 of the traces 16 prevents bonding problems between the chip carrier 12 and a printed circuit board. Those skilled in the art will readily recognize that other metals could be used in the traces 16, such as an all gold trace if gold bonding was used on both the chip-to-carrier and carrier-to-board connections. The barrier metallurgy is used also to improve adhesion between the gold and ceramic. Thus, the barrier metallurgy is in direct contact with the ceramic or silicon substrate, with the gold on top of the barrier metallurgy. The outer edges of the carrier 12 are 0.604 inches (+0.005/-0.005 inches) on each side. From the inner edge of the carrier 12, the traces 16 are brought out to the periphery of the carrier 12. The width of a trace 16, consistent from the inner edge of the carrier 12 and extending for a substantial portion of the length of the trace 16, is 0.002 inches (±0.0005 inches). The space between traces 16 at the inner edge of the carrier 12 is 0.002 inches (±0.0005 inches). At the outer edge of the carrier 12, the traces 16 are larger and less densely packed than at the inner edge. The width of a trace 16 at the outer edge of the carrier 12 is 0.0025 inches (±0.0005 inches). The space between traces 16 at the outer edge of the carrier 12 is 0.0025 inches (±0.0005 inches). The traces 16 are larger at the outer edge of the carrier 12 because they connect to large, bulky traces on a printed circuit board. At the inner edge of the carrier 12, on the other hand, the traces 16 are sized to match bonding pads on the IC chip, which bonding pads are usually very small and densely packed. Thus, the traces 16 fan out from the inner edge to the outer periphery of the chip carrier 12 to facilitate electrical interconnection between an IC and a printed circuit board. The creation of traces 16 surrounding each of the IC-receiving cavities 14 involves depositing metal layers in patterns on the wafer 10. Those skilled in the art will recognize that several techniques may be used for metal layer deposition, for example, sputtering, chemical-vapor deposition, plating, evaporation, etc., without departing from the scope of the present invention. The process steps are as follows in the order described in the preferred embodiment. The wafer 10 is first cleaned and sputtered with aluminum. The wafer 10 is then patterned using spray-coating and photolithographic methods. The aluminum is etched and the photoresist removed. The wafer 10 is then sputtered with four layers of metal in the following order and thickness: titanium (2000Å), titanium nitride (500Å), platinum (2000Å), and gold (1500Å). Next, the wafer 10 is patterned with photolithographic techniques so that the gold can be plated upwards. Gold is electroplated onto the sputtered gold, using the photoresist as a mask. The photoresist is removed and the exposed shorting metals are etched using ion beam milling, leaving the barrier metallurgy under all gold traces. Once the pattern of the traces 16 is complete, a passivation process may be used to prevent handling damage, for example, chemical-vapor deposition or sputtering the substrate with quartz or silicon nitride, etc. The final processing step is to separate the wafer 10 into its separate carriers 12. In the first preferred embodiment, a diamond saw separates wafer 10 into distinct carriers 12, but other techniques could also be used. Once the individual carriers 12 are fabricated, with the traces 16 extending from the inner edge to the outer periphery of the carrier 12, an IC die is placed in the cavity 14 of the carrier 12 and bonded therein using known techniques. The connections between the bonding pads of the IC and the traces 16 on the carrier 12 can be made by a variety of techniques, for example, aluminum wire bonding, TAB tape bonding, or wire ribbon bonding. Once the electrical connections are made from the IC to the traces 16 on the carrier 12, the carrier 12 is ready for hermetic sealing. FIG. 5 is a diagram of the lid 24 used to hermetically seal the carrier 12. Preferably, the lid 24 is comprised of the same material as the carrier 12. The lid 24 is 0.532 inches along each outer edge. Each inner edge of the recess 26 within the lid 24 is 0.472 inches in length. Note that the size of the lid 24 is such that only the gold portions 22 of the traces 16 are exposed. The lid 24 covers the aluminum portions 22 of the traces 16, forming a hermetic seal and thereby preventing corrosion. The gold portions 22 of the traces 16 extend underneath the lid 24 to the outer periphery of the carrier 12, thereby facilitating bonding. The lid 24 is sealed with glass, instead of metal, so that the prior art technique of burying electrically conductive vias in a non-conducting substrate is not required. If a prior art metal lid was used with the surface traces 16 of the present invention, the metal lid would electrically short the exposed traces 16. Thus, in the present invention, the glass-sealed lid 24 allows the traces 16 to reside on the surface of the carrier 12. FIG. 6 is a cross-sectional side view of the lid 24 for the carrier 12. In the preferred embodiment, the lid 24 is 0.043 inches thick. The recess 26 within the lid 24 extends to a depth of 0.019 inches (±0.001 inches). The lid 24 is sealed to the carrier 12 by placing low-temperature sealing glass on the lid-to-ceramic interface and baking the package to melt the sealing glass at approximately 425° C. Once it is hermetically sealed, the chip carrier 12 may be placed in a cavity or on the surface of a printed circuit board. The carrier-to-board connections may be made using bonding techniques well known in the art. Those skilled in the art will readily recognize that a wide variety of alternate techniques for hermetically sealing the carrier could be implemented. Depending upon the application, hermetically sealing the carrier may not be necessary. Those skilled in the art will readily recognize that a wide variety of processing techniques may be used in conjunction with the teachings of the present invention. For example, thick film techniques may be used to produce much larger traces to supply, for example, power to the chips, distribute clock signals, etc. In addition, multi-layered ceramic substrates may be used in which interlayers supply power to the integrated circuit chips. Such inter-layers may include buried resistors and capacitors. Second Preferred Embodiment FIG. 7 describes a second preferred embodiment, wherein the wafer 10 is fabricated in manner similar to the first preferred embodiment. In the second, preferred embodiment, the wafer 10 contains a plurality of cavities 14 as in the first preferred embodiment. However, the wafer 10 is not cut or otherwise separated into a plurality of carriers, each with an individual cavity 14. Thus, the wafer 10 itself is a single carrier for a plurality of ICs 30. Each cavity 14 is preferably the same dimensions as described in the first preferred embodiment. Metallized interconnects 16 electrically connect to bonding pads at the periphery of the cavities 14. The interconnects 16 may consist of single or multi-layer metallization. Pads 28 provide for lead bonding 32 or TAB (Tape Automated Bonding) 32 between ICs and traces 28 or between traces 28 and interconnects or devices external to the wafer 10. Preferably, the IC 30 is electrically connected to the carrier using a Tape Automated Bonding technique such as that described in the co-pending and commonly assigned patent application Ser. No. 07/366,604 filed Jun. 15, 1989 by E. F. Neumann et al. entitled "CHIP CARRIER WITH TERMINATING RESISTIVE ELEMENTS", which application is hereby incorporated by reference. A lid similar to the lid described in the first preferred embodiment may be used to seal each cavity 14. Individually sealing each cavity 14 enhances reworkability. Third Preferred Embodiment FIG. 8 describes a third preferred embodiment, wherein the wafer 10 is fabricated in a manner similar to the first and preferred embodiments. In the third preferred embodiment, the wafer 10 contains four large cavities 14, each cavity 14 holding a plurality of ICs 30. In the third preferred embodiment, like the second preferred embodiment, the wafer 10 is not cut or otherwise separated into a plurality of carriers. Thus, the wafer 10 itself is a single carrier for a plurality of ICs 30. Metallized interconnects 16 electrically connect the cavities 14. The interconnects 16 may consist of single or multi-layer metallization. Pads 28 provide for bonding between ICs and traces 28 or traces 28 and interconnects or devices external to the wafer 10. Preferably, the IC 30 is electrically connected to the carrier using a Tape Automated Bonding technique such as that described in the co-pending and commonly assigned patent application entitled "CHIP CARRIER WITH TERMINATING RESISTIVE ELEMENTS". Each cavity 14 is preferably sealed individually to enhance reworkability. Fourth Preferred Embodiment FIG. 9 describes a fourth preferred embodiment, wherein the wafer 10 is fabricated in a manner similar to the first, second, and third preferred embodiments. In the fourth preferred embodiment, the wafer 10 contains two large cavities 14, each cavity 14 holding a plurality of ICs arrayed in a linear manner. Such a configuration is especially useful for memory ICs with bonding pads on only two sides. In the fourth preferred embodiment, like the second and third preferred embodiments, the wafer 10 is not cut or otherwise separated into a plurality of carriers. Thus, the wafer 10 itself is a single carrier for a plurality of ICs 30. Metallized interconnects 16 electrically connect the cavities 14. The interconnects 16 may consist of single or multi-layer metallization. Pads 28 provide for bonding between ICs and traces 28 or traces 28 and interconnects or devices external to the wafer 10. Preferably, the IC 30 is electrically connected to the carrier using a Tape Automated Bonding technique such as that described in the co-pending and commonly assigned patent application entitled "CHIP CARRIER WITH TERMINATING RESISTIVE ELEMENTS". Each cavity 30 is preferably individually sealed to enhance reworkability. Fifth Preferred Embodiment FIG. 10 describes the fifth preferred embodiment, wherein the wafer 10 is fabricated in a manner similar to the first, second, third and fourth preferred embodiments. In the fifth preferred embodiment, the wafer 10 contains a plurality of cavities, each cavity holding one or more integrated circuits. The wafer is metallized according to the teachings of the present invention to provide metal interconnects 16 between the peripheries of the cavities 14. The interconnects 16 may consist of single or multi-layer metallization. Pads 28 provide for lead bonding 32 or TAB (Tape Automated Bonding) 32 between ICs and traces 28 or between traces 28 and interconnects or devices external to the wafer 10. In a fashion similar to the first preferred embodiment, however, the wafer is cut along the dashed lines 50, dividing the wafer into quadrants. Thus in the fifth preferred embodiment, a wafer may be divided into sub-sections, or quadrants as shown in FIG. 10, to produce a plurality of multiple-cavity chip carriers. Conclusion Although a specific embodiment has been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiment shown. For example, different processing steps, different-electrical connection patterns, different trace metals, or different barrier metals than those disclosed in the detailed description could be used. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
A method for simultaneously manufacturing metallized carriers from wafer-shaped substrates is described, wherein such wafer-shaped substrates permit the use of standard IC fabrication apparatus and methods. As a result, very thin and finely dimensioned traces can be deposited. Thin-film manufacturing techniques are used to create the high-density traces on the surface of the chip carriers, thereby permitting direct connections from the IC to the periphery of the carrier without the need for vias. A lid hermetically seals and protects the package. The traces are comprised of a plurality of metals to facilitate bonding, each of the metals homogeneous for a portion of the trace. One metal portion of the trace is of a type compatible with an IC chip placed in the carrier. Another metal portion of the trace is of a type compatible with a trace on a printed circuit board. A metal barrier is interposed between the metals to prevent metal diffusion from one metal to an adjoining portion of another metal.
Identify the most important claim in the given context and summarize it
[ "CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation, of application Ser.", "No. 07/647,937, filed Jan. 30, 1991 now abandoned, which is a division of application Ser.", "No. 07/506,729, filed Apr. 9, 1990 now U.S. Pat. No. 5,182,420, which is a continuation-in-part of application Ser.", "No. 07/343,506 filed Apr. 25, 1989, now abandoned, which application is incorporated herein by reference.", "BACKGROUND OF THE INVENTION 1.", "Field of the Invention This invention relates generally to chip carriers for high-density integrated circuits (ICs).", "In particular, it is directed to metallized chip carriers fabricated from wafer-shaped substrates.", "Description of Related Art As integrated circuits become more dense, often containing hundreds of I/O connections, prior art techniques of packaging become less suitable.", "Packaging is considered by many in the industry to be the pacing technology for integrated circuit development.", "Many designers have recognized the need for developing new techniques for defining high-resolution traces on chip carriers.", "Up until the present invention, however, creating the required high-resolution traces presented significant manufacturing problems.", "In the prior art, chip carriers are fabricated using substrates onto which metallized traces are placed to provide electrical connections from the periphery of the substrate to the integrated circuit packaged within.", "These traces are typically manufactured using thick-film technology.", "The need to provide increasing numbers of connections has resulted in thin-film technology being used as a partial solution to bring the traces from the integrated circuit to pins on the carrier.", "Prior art thin-film technology brings traces from the IC to vias within the carrier, and the vias provide connections to the pins.", "A primary shortcoming in the prior art is that thin-film technology can not be reliably used to bring the traces from the IC within the carrier to the periphery of the carrier.", "Thus, there is a need in the art for high-density interconnects on chip carriers, which can provide traces directly from the integrated circuit packaged within the carrier to the periphery of the carrier, fabricated entirely with thin-film techniques.", "This shortcoming of the prior art requires that vias be used to connect traces to pin connections, making the overall footprint of the carrier larger than desirable.", "There is also a need in the prior art to manufacture chip carriers in quantity using thin-film technology, such that a high yield rate is attained with traces as narrow as 5 mils or less.", "SUMMARY OF THE INVENTION To overcome limitations in the prior art described above and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention uses wafer-shaped substrates and thin-film manufacturing techniques to create high-density traces on chip carriers for direct connections from the IC to the periphery without the need of vias.", "One object of the present invention is to provide a method for manufacturing metallized chip carriers from substrates shaped similarly to semiconductor wafers.", "Wafer-shaped substrates permit the use of standard semiconductor fabrication apparatus and methods.", "As a result, very thin and finely dimensioned traces can be deposited simultaneously on a plurality of chip carriers.", "DESCRIPTION OF THE DRAWINGS In the drawings, where like numerals refer to like elements throughout the several views, FIG. 1 is a top view of a wafer used in creating the chip carrier of the present invention.", "FIG. 2 is a cross-sectional side view of a portion of the ceramic wafer taken along lines 2--2 of FIG. 1. FIG. 3A is an individual chip carrier fabricated from the ceramic wafer and the trace pattern thereon.", "FIG. 3B is a magnified view of the trace pattern along one edge of the chip carrier taken along the dotted lines of FIG. 3A.", "FIG. 4 is a cross-sectional side view of a trace on the chip carrier of FIG. 3A and FIG. 3B.", "FIG. 5 is a top view of the lid for the ceramic carrier.", "FIG. 6 is a cross-sectional side view of the lid of FIG. 5. FIG. 7 is a top view of a wafer as fabricated in a second preferred embodiment of the present invention.", "FIG. 8 is a top view of a wafer as fabricated in a third preferred embodiment of the present invention.", "FIG. 9 is a top view of a wafer as fabricated in a fourth preferred embodiment of the present invention.", "FIG. 10 is a top view of a wafer as fabricated in a fifth preferred embodiment of the present invention.", "FIG. 11 is a cross-sectional side view of a trace on the chip carrier of FIG. 3A and FIG. 3B including a first alternate barrier metallurgy.", "FIG. 12 is a cross-sectional side view of a trace on the chip carrier of FIG. 3A and FIG. 3B including a second alternate barrier metallurgy.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration four specific embodiments in which the invention may be practiced.", "It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.", "The present invention describes metallized chip carriers for high-density ICs and the steps required to fabricate these carriers.", "The preferred embodiment of the present invention uses thin-film techniques to deposit a large number of finely dimensioned traces on the surface of a substrate.", "Central to this invention is the use of standard semiconductor processing apparatus and methods in the fabrication of the chip carriers.", "First Preferred Embodiment Referring initially to FIG. 1, a substrate in a first preferred embodiment is shaped into a wafer 10.", "The substrate may be ceramic, such as aluminum oxide, aluminum nitrate, beryllium oxide, etc.", ", or silicon.", "This wafer 10 is circularly shaped and keyed substantially similar to semiconductor wafers, which permits the use of IC fabrication apparatus and methods.", "The flat portion or key 8 of the wafer 10 is a reference key, ensuring the proper orientation of the wafer 10 during fabrication.", "Each wafer 10 is comprised of an array of cavities 14.", "In the first preferred embodiment, the wafer 10 contains 21 cavities 14.", "Thus, a plurality of chip carriers, generally identified by reference number 12, can be fabricated simultaneously.", "Each cavity 14 is substantially square and measures 0.426 inches in length (±0.003 inches) on each side.", "These cavities 14 will eventually contain an IC chip.", "The top surface of the IC is approximately planar with the top surface of the chip carrier 12.", "FIG. 2 is a cross-sectional side view of wafer 10.", "The wafer 10 is 0.060 inches (+0.002/-0.001 inches) thick.", "Each cavity 14 is recessed within the wafer 10 to a depth of 0.030 inches (±0.002 inches).", "If the substrate is ceramic, then the cavities may be fabricated by molding or other techniques known in the ceramic arts.", "For example, ceramic may be molded, milled, etc.", "Anvil and slurry milling will provide tighter tolerances than molding.", "When milled, the cavities are typically added after metallization, thereby avoiding problems with shrinkage of the cavities due to the sintering after punching or pressing the cavities.", "If the substrate is comprised of silicon, then the cavities may be fabricated by etching or other techniques known in the silicon arts.", "The cavities can be etched in the silicon substrate as the first step in production or at any other step along the way, provided that the patterning material will sufficiently protect any metallization currently on the package.", "For example, if the cavities are etched in silicon after aluminum, titanium, platinum, and gold metallization layers have been deposited, the masking material must be able to sufficiently protect these metals with their large dimensions.", "An advantage of using silicon is the ability to use silicon's electrical properties for a substrate voltage bias, buried resistors, etc.", "FIG. 3A shows a top view of a finished carrier 12 fabricated from the wafer 10.", "FIG. 3B shows a magnified view of the trace pattern along one edge of the carrier 12 taken along the dotted lines of FIG. 3A.", "The carrier 12 contains 90 traces per side (360 traces total), generally identified by reference number 16.", "The traces 16 are comprised of a plurality of metals.", "Using a plurality of metals in the trace 16 enhances bonding by allowing the trace 16 to metallically match both the bonding pads on the IC and the traces on the printed circuit board.", "FIG. 4 is a magnified, cross-sectional side view of an individual trace 16 that better illustrates the barrier metallurgy 20.", "The aluminum portion 22 is created first, the barrier metallurgy 20 is added on top of the aluminum, and finally, the gold portion 18 is added atop the barrier metallurgy 20.", "FIGS. 11 and 12 illustrate individual traces fabricated with alternate barrier metallurgies.", "Each metal is homogeneous for its portion of the trace 16.", "The inner length of each trace 16, generally identified by reference number 122 is preferably comprised of aluminum (Al).", "The outer length of each trace 16, generally identified by reference number 18, is preferably comprised of gold (Au).", "At the point where the inner length 22 meets the outer length 18, denoted by the dotted line 20 in FIG. 3, a barrier metallurgy is used.", "The barrier metallurgy 20 prevents the aluminum and gold from intermixing and forming "purple plague"", "and Kirkendall voiding.", "If Kirkendall voiding occurs, then the trace 16 could form an intermittent open due to localized heating from the electrical current, differences in expansion coefficients, and poor bond integrity.", "Those skilled in the art will readily recognize that other barrier metals could be used in the barrier metallurgy 20, depending upon a number of fabrication factors.", "For example, in a low temperature environment, titanium tungsten (TiW) or titanium under platinum could be used as shown in FIG. 11.", "At high temperatures, different combinations may be desired to improve adhesion and prevent diffusion of the metals.", "The rate of diffusion is at least partially determined by the temperature of the substrate.", "For example, nickel over chrome, platinum over titanium nitride over titanium (see FIG. 12), platinum over titanium tungsten over titanium or platinum over titanium tungsten nitride over titanium.", "Those skilled in the art will recognize that other metals such as palladium may be substituted for platinum to form the barrier metallurgy.", "Aluminum is used for the inner portion 22 of the traces 16 because the electrical interconnections to the IC are aluminum.", "Thus, using aluminum for the inner portion 22 of the traces 16 prevents bonding problems between the IC and the chip carrier 12.", "Gold is used for the outer portion 18 of the traces 16 because the electrical interconnections to the printed circuit board are gold.", "Thus, using gold for the outer portions 18 of the traces 16 prevents bonding problems between the chip carrier 12 and a printed circuit board.", "Those skilled in the art will readily recognize that other metals could be used in the traces 16, such as an all gold trace if gold bonding was used on both the chip-to-carrier and carrier-to-board connections.", "The barrier metallurgy is used also to improve adhesion between the gold and ceramic.", "Thus, the barrier metallurgy is in direct contact with the ceramic or silicon substrate, with the gold on top of the barrier metallurgy.", "The outer edges of the carrier 12 are 0.604 inches (+0.005/-0.005 inches) on each side.", "From the inner edge of the carrier 12, the traces 16 are brought out to the periphery of the carrier 12.", "The width of a trace 16, consistent from the inner edge of the carrier 12 and extending for a substantial portion of the length of the trace 16, is 0.002 inches (±0.0005 inches).", "The space between traces 16 at the inner edge of the carrier 12 is 0.002 inches (±0.0005 inches).", "At the outer edge of the carrier 12, the traces 16 are larger and less densely packed than at the inner edge.", "The width of a trace 16 at the outer edge of the carrier 12 is 0.0025 inches (±0.0005 inches).", "The space between traces 16 at the outer edge of the carrier 12 is 0.0025 inches (±0.0005 inches).", "The traces 16 are larger at the outer edge of the carrier 12 because they connect to large, bulky traces on a printed circuit board.", "At the inner edge of the carrier 12, on the other hand, the traces 16 are sized to match bonding pads on the IC chip, which bonding pads are usually very small and densely packed.", "Thus, the traces 16 fan out from the inner edge to the outer periphery of the chip carrier 12 to facilitate electrical interconnection between an IC and a printed circuit board.", "The creation of traces 16 surrounding each of the IC-receiving cavities 14 involves depositing metal layers in patterns on the wafer 10.", "Those skilled in the art will recognize that several techniques may be used for metal layer deposition, for example, sputtering, chemical-vapor deposition, plating, evaporation, etc.", ", without departing from the scope of the present invention.", "The process steps are as follows in the order described in the preferred embodiment.", "The wafer 10 is first cleaned and sputtered with aluminum.", "The wafer 10 is then patterned using spray-coating and photolithographic methods.", "The aluminum is etched and the photoresist removed.", "The wafer 10 is then sputtered with four layers of metal in the following order and thickness: titanium (2000Å), titanium nitride (500Å), platinum (2000Å), and gold (1500Å).", "Next, the wafer 10 is patterned with photolithographic techniques so that the gold can be plated upwards.", "Gold is electroplated onto the sputtered gold, using the photoresist as a mask.", "The photoresist is removed and the exposed shorting metals are etched using ion beam milling, leaving the barrier metallurgy under all gold traces.", "Once the pattern of the traces 16 is complete, a passivation process may be used to prevent handling damage, for example, chemical-vapor deposition or sputtering the substrate with quartz or silicon nitride, etc.", "The final processing step is to separate the wafer 10 into its separate carriers 12.", "In the first preferred embodiment, a diamond saw separates wafer 10 into distinct carriers 12, but other techniques could also be used.", "Once the individual carriers 12 are fabricated, with the traces 16 extending from the inner edge to the outer periphery of the carrier 12, an IC die is placed in the cavity 14 of the carrier 12 and bonded therein using known techniques.", "The connections between the bonding pads of the IC and the traces 16 on the carrier 12 can be made by a variety of techniques, for example, aluminum wire bonding, TAB tape bonding, or wire ribbon bonding.", "Once the electrical connections are made from the IC to the traces 16 on the carrier 12, the carrier 12 is ready for hermetic sealing.", "FIG. 5 is a diagram of the lid 24 used to hermetically seal the carrier 12.", "Preferably, the lid 24 is comprised of the same material as the carrier 12.", "The lid 24 is 0.532 inches along each outer edge.", "Each inner edge of the recess 26 within the lid 24 is 0.472 inches in length.", "Note that the size of the lid 24 is such that only the gold portions 22 of the traces 16 are exposed.", "The lid 24 covers the aluminum portions 22 of the traces 16, forming a hermetic seal and thereby preventing corrosion.", "The gold portions 22 of the traces 16 extend underneath the lid 24 to the outer periphery of the carrier 12, thereby facilitating bonding.", "The lid 24 is sealed with glass, instead of metal, so that the prior art technique of burying electrically conductive vias in a non-conducting substrate is not required.", "If a prior art metal lid was used with the surface traces 16 of the present invention, the metal lid would electrically short the exposed traces 16.", "Thus, in the present invention, the glass-sealed lid 24 allows the traces 16 to reside on the surface of the carrier 12.", "FIG. 6 is a cross-sectional side view of the lid 24 for the carrier 12.", "In the preferred embodiment, the lid 24 is 0.043 inches thick.", "The recess 26 within the lid 24 extends to a depth of 0.019 inches (±0.001 inches).", "The lid 24 is sealed to the carrier 12 by placing low-temperature sealing glass on the lid-to-ceramic interface and baking the package to melt the sealing glass at approximately 425° C. Once it is hermetically sealed, the chip carrier 12 may be placed in a cavity or on the surface of a printed circuit board.", "The carrier-to-board connections may be made using bonding techniques well known in the art.", "Those skilled in the art will readily recognize that a wide variety of alternate techniques for hermetically sealing the carrier could be implemented.", "Depending upon the application, hermetically sealing the carrier may not be necessary.", "Those skilled in the art will readily recognize that a wide variety of processing techniques may be used in conjunction with the teachings of the present invention.", "For example, thick film techniques may be used to produce much larger traces to supply, for example, power to the chips, distribute clock signals, etc.", "In addition, multi-layered ceramic substrates may be used in which interlayers supply power to the integrated circuit chips.", "Such inter-layers may include buried resistors and capacitors.", "Second Preferred Embodiment FIG. 7 describes a second preferred embodiment, wherein the wafer 10 is fabricated in manner similar to the first preferred embodiment.", "In the second, preferred embodiment, the wafer 10 contains a plurality of cavities 14 as in the first preferred embodiment.", "However, the wafer 10 is not cut or otherwise separated into a plurality of carriers, each with an individual cavity 14.", "Thus, the wafer 10 itself is a single carrier for a plurality of ICs 30.", "Each cavity 14 is preferably the same dimensions as described in the first preferred embodiment.", "Metallized interconnects 16 electrically connect to bonding pads at the periphery of the cavities 14.", "The interconnects 16 may consist of single or multi-layer metallization.", "Pads 28 provide for lead bonding 32 or TAB (Tape Automated Bonding) 32 between ICs and traces 28 or between traces 28 and interconnects or devices external to the wafer 10.", "Preferably, the IC 30 is electrically connected to the carrier using a Tape Automated Bonding technique such as that described in the co-pending and commonly assigned patent application Ser.", "No. 07/366,604 filed Jun. 15, 1989 by E. F. Neumann et al.", "entitled "CHIP CARRIER WITH TERMINATING RESISTIVE ELEMENTS", which application is hereby incorporated by reference.", "A lid similar to the lid described in the first preferred embodiment may be used to seal each cavity 14.", "Individually sealing each cavity 14 enhances reworkability.", "Third Preferred Embodiment FIG. 8 describes a third preferred embodiment, wherein the wafer 10 is fabricated in a manner similar to the first and preferred embodiments.", "In the third preferred embodiment, the wafer 10 contains four large cavities 14, each cavity 14 holding a plurality of ICs 30.", "In the third preferred embodiment, like the second preferred embodiment, the wafer 10 is not cut or otherwise separated into a plurality of carriers.", "Thus, the wafer 10 itself is a single carrier for a plurality of ICs 30.", "Metallized interconnects 16 electrically connect the cavities 14.", "The interconnects 16 may consist of single or multi-layer metallization.", "Pads 28 provide for bonding between ICs and traces 28 or traces 28 and interconnects or devices external to the wafer 10.", "Preferably, the IC 30 is electrically connected to the carrier using a Tape Automated Bonding technique such as that described in the co-pending and commonly assigned patent application entitled "CHIP CARRIER WITH TERMINATING RESISTIVE ELEMENTS".", "Each cavity 14 is preferably sealed individually to enhance reworkability.", "Fourth Preferred Embodiment FIG. 9 describes a fourth preferred embodiment, wherein the wafer 10 is fabricated in a manner similar to the first, second, and third preferred embodiments.", "In the fourth preferred embodiment, the wafer 10 contains two large cavities 14, each cavity 14 holding a plurality of ICs arrayed in a linear manner.", "Such a configuration is especially useful for memory ICs with bonding pads on only two sides.", "In the fourth preferred embodiment, like the second and third preferred embodiments, the wafer 10 is not cut or otherwise separated into a plurality of carriers.", "Thus, the wafer 10 itself is a single carrier for a plurality of ICs 30.", "Metallized interconnects 16 electrically connect the cavities 14.", "The interconnects 16 may consist of single or multi-layer metallization.", "Pads 28 provide for bonding between ICs and traces 28 or traces 28 and interconnects or devices external to the wafer 10.", "Preferably, the IC 30 is electrically connected to the carrier using a Tape Automated Bonding technique such as that described in the co-pending and commonly assigned patent application entitled "CHIP CARRIER WITH TERMINATING RESISTIVE ELEMENTS".", "Each cavity 30 is preferably individually sealed to enhance reworkability.", "Fifth Preferred Embodiment FIG. 10 describes the fifth preferred embodiment, wherein the wafer 10 is fabricated in a manner similar to the first, second, third and fourth preferred embodiments.", "In the fifth preferred embodiment, the wafer 10 contains a plurality of cavities, each cavity holding one or more integrated circuits.", "The wafer is metallized according to the teachings of the present invention to provide metal interconnects 16 between the peripheries of the cavities 14.", "The interconnects 16 may consist of single or multi-layer metallization.", "Pads 28 provide for lead bonding 32 or TAB (Tape Automated Bonding) 32 between ICs and traces 28 or between traces 28 and interconnects or devices external to the wafer 10.", "In a fashion similar to the first preferred embodiment, however, the wafer is cut along the dashed lines 50, dividing the wafer into quadrants.", "Thus in the fifth preferred embodiment, a wafer may be divided into sub-sections, or quadrants as shown in FIG. 10, to produce a plurality of multiple-cavity chip carriers.", "Conclusion Although a specific embodiment has been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiment shown.", "For example, different processing steps, different-electrical connection patterns, different trace metals, or different barrier metals than those disclosed in the detailed description could be used.", "This application is intended to cover any adaptations or variations of the present invention.", "Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof." ]
This application is a continuation-in-part of application Ser. No. 430,696 filed 11/1/89, now abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a catalyst component and a process for preparing said catalyst component. The catalyst component may be employed with or without a cocatalyst in the polymerization of olefins to polyolefins. The process for preparing the catalyst component comprises the fluoriding of a support and further reaction of the support with a vanadium compound to produce a novel catalyst component which allows the molecular weight distribution of the polyolefins to be controlled by controlling the amount of fluorination and the fluorination temperature. 2. Description of the Prior Art The use of vanadium-based catalysts in the polymerization of olefins is well known. When unsupported, vanadium catalysts usually assume the form of an oil or gum, and tend to cause fouling of the polymerization reactor. As a consequence, unsupported vanadium-based catalysts are unsuitable for use in a slurry or gas phase reaction process. Supported vanadium catalysts suffer from the fouling problem to a lesser degree. However supported vanadium catalysts suffer from a series of shortcomings. First, supported vanadium catalysts tend to produce polymers having too broad molecular weight distributions (MWD), with the polymer including a significant amount of low molecular weight oligomers. These oligomers, when present in polymers used in the manufacture of blow molded articles, produce an unacceptable amount of smoke. It would be highly desirable to have a supported vanadium catalyst which could be used in a gas or slurry phase polymerization process to produce polymer of narrower MWD for use in blow molding resin. Similarly, narrow MWD's are desirable for resin applications such as injection molding or linear low density polyethylene (LLDPE) film production. For other applications, such as the manufacture of high density polyethylene (HDPE) films, it would be desirable to produce a high molecular weight resin having a broad MWD. In yet other applications, such as wire and cable coatings manufacture, it is desirable for the resin to have a MWD of intermediate breadth. It would thus be desirable to have a supported vanadium catalyst for the production of high molecular weight polyolefins having an easily and accurately controllable MWD ranging from broad to narrow, as desired, depending on the intended use of the resin product. A clear need exists in the industry for a supported vanadium catalyst which can be tailored to provide resins of a specific MWD over a wide molecular weight range. A second shortcoming of supported vanadium catalysts is that these catalysts, when used in the polymerization of ethylene or in the copolymerization of ethylene with other 1-olefins, exhibit low activity in comparison to supported titanium-based catalysts. It would thus be desirable to have a supported vanadium catalyst which would have increased activity. A third shortcoming of supported vanadium catalysts is their need for relatively high levels of hydrogen during polymerization to control resin molecular weight. It would be desirable to have a supported vanadium catalyst that would have increased response to hydrogen for affecting chain termination and controlling molecular weight. Finally, supported vanadium catalysts require relatively high levels of comonomer to prepare medium and low density resins. It would be desirable to have a supported vanadium catalyst which would have increased response to comonomer to effect resin density reduction. Good comonomer utilization means that less comonomer is needed to give the target resin density. This is important for both slurry and gas phase polymerization since large amounts of comonomer lead to upsets in process conditions by increasing the solubilizing power of the slurry diluent or forming droplets in the gas phase. It is well known that fluorided supports can be used to advantage with chromium catalysts. In that context, fluorination increases chromium catalyst activity, narrows resin MWD, but decreases resin melt indices. Decreases in resin melt index (MI) are indicative of increased molecular weight and decreased response of the catalyst to hydrogen. Fluorination of chromium catalyst supports was disclosed in U.S. Pat. Nos. 2,825,721, and 2,951,816. U.S. Pat. No. 3,130,188 described the use of ammonium silicofluoride in conjunction with supports for chromium-based catalysts. U.S. Pat. No 4,011,382 discloses a titanated and fluorided support for a chromium catalyst and notes that increasing the fluorine content, while improving the rate of incorporation of comonomer, also decreases the resin melt index. Similarly, U.S. Pat. No. 4,077,904 describes a fluorided silica support for a chromium catalyst. The data show that fluorination decreased resin melt index and had no effect on MIR, i.e. that the average molecular weight increased while the MWD distribution remained unchanged. The earliest mention of a vanadium compound associated with fluorine for olefin polymerization is in U.S. Pat. No. 3,304,295 in connection with an unsupported catalyst mixture U.S. Pat. No. 4,262,105 discloses the fluorination of support material consisting of magnesium compounds for TiCl 4 catalysts for the polymerization of ethylene. U.S. Pat. No. 3,936,431 covers fluorided alumina-silica and alumina-calcium oxide as supports. Similarly, U.S. Pat. No. 4,258,159 discloses fluorided alumina and magnesium chloride as supports for titanium alkoxide catalysts. U.S. Pat. No. 4,359,403 teaches the addition of fluorine-containing compounds to silica prior to or during heating for the sole purpose of improving the activity of the silica supported catalyst. The catalyst is prepared by reacting the fluorided silica with a magnesium compound and then with the active metal. The patent also teaches the addition of alcohol for the purpose of improving the catalyst response to hydrogen. No mention is made of improved hydrogen response or comonomer response caused by the fluorination, nor is any mention made of the ability to control molecular weight distribution through independent control of the amount of fluorination and the fluorination temperature. SUMMARY OF THE INVENTION This invention discloses a novel vanadium-based catalyst component and a method for producing said catalyst component. The catalyst component, when used alone or in conjunction with a cocatalyst, provides a catalyst system having unique properties for olefin polymerization, including increased catalytic activity, increased response to hydrogen for chain termination, and increased response to comonomer for controlling resin density. The catalyst system of the invention provides the ability to control the molecular weight distribution through independent control of the amount of fluorination and the temperature at which the support is fluorinated. While fluorination of supports for vanadium-based catalysts, as taught by the present invention has the effect of increasing catalyst activity and narrowing MWD's, fluorination also, unexpectedly, has the effect of increasing resin melt indices, i.e. increasing hydrogen response. In addition, fluorination in accordance with the present invention decreases resin density which is indicative of increased comonomer response. In view of the high activity of the catalyst system of this invention it is generally not necessary to deash the polymer product since it will generally contain lower amounts of catalyst residues than polymer product produced in the presence of conventional catalyst. The ability of this catalyst system to control the MWD of the polymer product through fluorination substantially eliminates the formation of low weight oligomer thereby reducing the amount of smoke and facilitating the use of a polyolefin resin produced by the catalyst system as a blow molding resin. Moreover, the flexibility provided by this catalyst in allowing the tailoring of the breadth of the MWD over a wide range of molecular weights by varying the extent of fluorination and/or the fluorination temperature, permits the production of polymers having properties optimally suited for specific applications. The catalyst component disclosed in this invention may be used alone or in combination with an alkyl aluminum cocatalyst under conditions characteristic of Ziegler polymerization. The process for producing this novel catalyst component comprises the steps of dry mixing a support material with a fluorine compound. The mixture is then heated to some desirable fluorination temperature. Next, the support material is treated with a vanadium compound. The catalyst component of this invention may be used to produce polymer having a desired MWD by judiciously selecting the fluorine content and the fluorination temperature. The support material is selected from the group consisting of silica, alumina, silica-alumina mixtures, talc, zirconia, thoria, and metal oxides from the metals of Group IIA, IVA and IVB of the Periodic Table of the Elements. The fluorine compound is selected from the group consisting of (NH 4 ) 2 SiF 6 , NH 4 F, NH 4 HF, NH 4 BF 4 , KF, AlF 3 , HF, Zn(BF 4 ) 2 , Ni(BF 4 ) 2 , Sn(BF 4 ) 2 , (NH 4 ) 2 TiF 6 and the like. The disclosed catalyst may be employed, either by itself or in conjunction with a cocatalyst, in the gas phase, high pressure, solution, or slurry processes for the production of polyolefin resins. The catalyst may be usefully employed in the polymerization of ethylene and other alpha-olefins, particularly alpha-olefins having from 3 to 8 carbon atoms and in the copolymerization of these with other 1-olefins or diolefins, such as propylene, butene, pentene and hexene, butadiene, 1,4-pentadiene, and the like, so as to form copolymers of low and medium densities. The catalyst is particularly useful for the polymerization of ethylene and the copolymerization of ethylene with other alpha-olefins in gas phase processes to produce HDPE or LLDPE. DESCRIPTION OF THE PREFERRED EMBODIMENTS The catalyst component of the present invention comprises the solid reaction product of (A) a fluorine compound in the presence of an inert support material, (B) a vanadium compound, (C) an optional halogenating agent, and (D) an optional reducing agent. The catalyst component may optionally be reacted with (E) an organoaluminum compound cocatalyst to form a catalyst system. In accordance with this invention, the order of addition of ingredients in forming the vanadium containing catalyst can vary. In a preferred embodiment of this invention, after the inert support material is treated with the fluorine compound, the next substantial reaction of the fluorided support material should be conducted with the vanadium compound. In this embodiment, where there is no substantial reaction between the fluorided support material and any other catalyst component prior to the reaction with the vanadium compound, the catalyst produced has the unexpected effect of increasing the melt indices of the resulting polymer. It is not necessary in the preparation of the catalyst of this preferred embodiment for there to be complete isolation of the fluorided support from other catalyst components prior to contact between the fluorided support and the vanadium compound. It is only necessary that, at the time of addition of the vanadium compound, there should be enough remaining increased activity from the fluorination of the support so that the vanadium compound, and not some other catalyst component, will have substantial benefit of the fluorination of the support. Therefore, it is within the scope of this invention, that some catalyst components may be contacted with the fluorinated support in small reactive quantities prior to contact with the vanadium compound, as long as all of the benefits of fluorination are not used up prior to contact with the vanadium compound. In the preferred embodiment of this invention, the silica support material is dry mixed with the ammonium silicofluoride fluorine compound. Both the silica and the ammonium silicofluoride are solid particulates. Dry mixing is accomplished by simply blending the two solids. Alternatively, the fluorine compound could be dissolved in water and sprayed onto the dry silica, or the fluorine compound could be dissolved in water and added to an aqueous suspension of the silica, or the dry fluorine compound could be added to an aqueous suspension of the silica. However, when the fluorine compound is a solid particulate, dry blending is preferred. The mixture is then heated to a desirable temperature. The amount of fluorine used and the temperature to which the mixture is raised influence the narrowness of the MWD of the polymers formed using the catalyst of this invention. The support material can be any of the solid particulate porous supports such as talc, silica, zirconia, thoria, magnesia, and titania. Preferably the support material is a Group IIA, IIIA, IVA and IVB oxide in finely divided form. Suitable inorganic oxide materials which are desirably employed in accordance with this invention include silica, alumina, and silica-alumna and mixtures thereof, with silica being most preferred. Other inorganic oxides that may be employed either alone or in combination with the silica, alumina, or silica-alumina are magnesia, titania, zirconia, and the like. The preferred fluorine compound is ammonium silicofluoride (ASF), (NH 4 ) 2 SiF 6 , but many other fluorine containing compounds may be used. Among the fluorine compounds which may be used are hydrogen fluoride, HF, fluorides of ammonium and metals, such as KF, KF.HF, NH 4 F, NH 4 F.HF, AlF 3 , complex fluorides of ammonium and metals, Sn(BF 4 ) 2 and the like. The fluorine treated support, slurried in a hydrocarbon, is treated with a vanadium compound. The preferred vanadium compounds which may be usefully employed in the preparation of the catalyst component of this invention are well known in the art and may be represented by the formulas: ##STR1## where "x" is a number from 0 to 3 and R is a hydrocarbon radical (2) VCl y (OR) 4-y where "y" is a number from 3 to 4 and R is a hydrocarbon radical (3) ##STR2## where "z" is a number from 2 to 3 and (AcAc) is an acetyl acetonate group, (4) ##STR3## where (AcAc) is an acetyl acetonate group, and (5) VCl 3 .nL where "n" is a number from 2 to 3 and L is a Lewis base, such as tetrahydrofuran, which can form hydrocarbon-soluble complexes with VCl 3 . In formulas (1) and (2) above, R preferably represents a C 1 to C 8 aliphatic radical free of aliphatic unsaturation or an aromatic hydrocarbon radical such as a straight or branched alkyl, aryl, cycloalkyl, alkanyl, or aralkyl group, such as methyl, ethyl, propyl, isopropyl, butyl, n-butyl, i-butyl, t-butyl, pentyl, hexyl, cyclohexyl, octyl, benzyl, dimethyl, phenyl, naphthyl, and the like. Illustrative, but not limiting examples of the vanadium compounds are vanadyl trichloride, vanadium tetrachloride, vanadium tetrabutoxide, alkoxy vanadium chloride, vanadium trichloride, vanadyl acetylacetonate, vanadyl dichloroacetylacetonate, vanadyl chlorodiacetylacetonate, vanadium trichloride complexed with tetrahydrofuran, vanadyl tribromide, vanadium tetrabromide, and the like. The vanadium compound is preferably added to the reaction mixture in the form of a solution. The solvent can be any of the well-known inert hydrocarbon solvents such as hexane, heptane, benzene, toluene, and the like. In accordance with this invention, the optional halogenating agents are employed to obtain increased catalytic activity. The halogenating agents may be used to increase activity without detrimentally affecting the molecular weight distributions obtainable in accordance with this invention in which the content of the oligomer is reduced. The halogenating agents which can be employed are chlorinating, brominating and iodinating agents. The halogenating agents are desirably strong halogenating agents although weaker halogenating agents may be used. The halogenating agents can be liquid or gaseous under the reaction conditions. Illustrative but non-limiting examples of the strong halogenating agents that can be usefully employed in accordance with this invention are the silicon halides and the hydrocarbyl halides. The silicon halides can be represented by the formula X a SiR b s in which X is a halogen, R s is hydrogen, alkyl, cycloalkyl or aryl radical containing 1 to 20 carbon atoms, "a"+"b"=4 and "a" is at least 1. Illustrative examples of the silicon compounds are silicon tetrachloride, silicon tetrabromide, chlorosilanes such as, for example, trichlorosilane, trimethylchlorosilane, dimethyldichlorosilane, ethyltrichlorosilane, diethyldichlorosilane, dichlorodibutylsilane, trichlorobutylsilane, tribromobutylsilane, bromotrimethylsilane, and the like. Other halogenating agents are the hydrocarbyl halides which include carbon tetrachloride, chloroform, 1,1,1-trichloroethane, dichloromethane, trichlorofluormethane, and the like. The preferred halogenating agents are strong activating chlorinating agents, among which the most preferred are silicon tetrachloride, trichlorofluoromethane, trichloroethane, and the like. Illustrative of weak activating chlorinating agents are the thionyl halides, such as SOCl 2 . The halogenating agent may be conveniently added to the reaction slurry consisting of the reaction product of the fluorided support material, the vanadium compound, and the organoaluminum compound. The halogenating agent may be added as a pure compound or in the form of a solution with an inert solvent such as, for example, an aliphatic hydrocarbon solvent or an aromatic hydrocarbon solvent, or int may be added as a gas. The slurrying of the support material, as mentioned above, is conducted in an inert solvent. The inert solvent can be the same as that employed to dissolve the individual ingredients prior to the treatment step. Preferred solvents include mineral oils and the various hydrocarbons which are liquid at reaction temperatures and in which the individual ingredients are soluble. The amount of solvent used is not critical. The amount employed should, however, be sufficient to provide adequate capability for heat transfer away from the catalyst components during reaction and to permit good mixing. The catalyst component may optionally be reacted with a reducing agent. The reducing agent can be represented by the general formula R' m AlX 3-m wherein R' represents an alkyl group, cycloalkyl group or aryl group, X represents a halogen atom and "m" represents a suitable numeral equal to or greater than 1 and less than or equal to 3, or mixtures or complex compounds thereof. In particular, it is preferable to employ alkyl aluminum halide compounds wherein the alkyl groups have from 1 to 18 carbon atoms, preferably 1 to 9 carbon atoms and the halogen is chlorine. Illustrative but non-limiting examples of the organoaluminum compounds which may be suitably employed are the trialkylaluminums such as trimetylaluminum, triethylaluminum, tributylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, and the like. Illustrative examples of the diaklyaluminum halides are diethylaluminum chloride, diethylaluminum fluoride, dimethylaluminum chloride, dibutylaluminum chloride, diethylaluminum bromide, diethyaluminum iodide and dibutylaluminum iodide. Examples of the monoalkylaluminum dihalides are methylaluminum dichloride, ethylaluminum dichloride, butylaluminum dichloride, isobutylaluminum dichloride, ethylaluminum dibromide, ethylaluminum diiodide, butylaluminum dibromide, and butylaluminum diiodide. Moreover, the sesquihalides can be suitably employed such as methylaluminum sesquichloride and ethylaluminum sesquichloride and the like. Preferably, isobutylaluminum dichloride is used. The alkylaluminum may conveniently be added to the agitated slurry containing the particulate supports in the form of a solution with a dry hydrocarbon such as hexane, benzene, toluene, and the like. Alternatively, the alkylaluminum may be added to the slurry in undiluted form. The amounts of catalytic ingredients employed in the preparation of the supported catalyst component can vary over a wide range. The fluorine containing compound is added to the support at a concentration of about 0.01 to 1.0 millimoles F/g of dried support, preferably in the range of about 0.1 to about 0.6 millimoles F/g of dried support and especially in the range of about 0.2 to 0.4 millimoles F/g of dried support. The precise amount of fluorine containing compound added directly affects the narrowness of the MWD of the resulting polyolefins formed using the catalyst and must be judiciously selected to effect MWD's of desired breadth. The reaction of the support material with the fluorine containing compound takes place at temperatures of from 200° C. to 1000° C., preferably from 350° C. to 800° C. The precise temperature to which the mixture is heated directly affects the narrowness of the MWD of the resulting polyolefins formed using the catalyst and must be judiciously selected to affect MWD's of desired narrowness. The vanadium compound is added to the slurry of inert support at a concentration of about 0.05 to 2.0 millimoles V/g of dried support, preferably in the range of about 0.1 to about 1.5 millimoles V/g of dried support and especially in the range of about 0.2 to 1.0 millimoles V/g of dried support. Generally, the reaction steps may be conducted at temperatures in the range of about -50° C. to about 150° C. Preferred temperature ranges are from about -30° C. to about 60° C. with -10° C. to about 50° C. being most preferred. The catalyst components prepared in accordance with this invention are usefully employed with cocatalysts well known in the art of the Ziegler catalysis for polymerization of olefins. Typically, the cocatalysts which are used together with the transition metal containing catalyst component are organometallic compounds of Group Ia, IIa and IIIa metals such as aluminum alkyls, aluminum alkyl hydrides, lithium aluminum alkyls, zinc alkyls, magnesium alkyls and the like. The cocatalysts preferably used are the organoaluminum compounds. The preferred alkylaluminum compounds are represented by the formula AlR' n X' 3-n wherein R' is hydrogen, hydrocarbyl or substituted hydrocarbyl group and n is as defined herein above. Preferably R' is an alkyl group having from 2 to 10 carbon atoms. X' is halogen and preferably chlorine. Illustrative examples of the cocatalyst material are ethyl aluminum dichloride, ethyl aluminum sesquichloride, diethyl aluminum chloride, aluminum triethyl, aluminum tributyl, diisobutyl aluminum hydride, diethyl aluminum ethoxide and the like. Aluminum trialkyl compounds are most preferred with triisobutylaluminum and aluminum triethyl being highly desirable. Cocatalysts are added to the polymerization reactor at a molar ratio to V of about 50 to 250 however, greater or lesser amounts can be usefully employed. Preferably, the Al/V ratio is in the range of about 50 to about 150 and especially in the range of about 75 to 100. Improved yields can be further obtained by employing polymerization promoters (activators) in combination with the catalyst system of this invention. The polymerization activators, in accordance with this invention, are preferably chlorocarbon activators. The activators are generally added to the polymerization reactor as a separate component. However, in the alternative, the activator can be adsorbed onto the surface of the catalyst component of this invention. The activator serves to significantly increase the productivity of the catalyst. Illustrative but non-limiting examples of the chlorocarbons are CHCl 3 , CFCl 3 , CH 2 Cl 2 , ethyltrichloroacetate, methyltrichloroacetate, hexachloropropylene, butylperchlorocrotonate, 1,3-dichloropropane, 1,2,3-trichloropropane, and 1,1,2-trichlorotrifluoroethane, etc. The activators may be gases or liquids at the conditions of polymerization. The catalyst system comprising the organoaluminum cocatalyst and the vanadium-containing solid catalyst component of this invention is preferably employed for the polymerization of ethylene. However, this catalyst system can also be used to polymerize other alpha-olefins having from 3 to 20 carbon atoms, ethylene copolymers with other alpha-olefins or diolefins, and ethylene copolymers with other alpha-olefins or diolefins. The catalyst system may be usefully employed to produce polyethylene or copolymers of ethylene. The catalyst is especially useful for the preparation of resins for blown film and blow molding applications. The olefins can be polymerized in the presence of the catalysts of this invention by any suitable known process such as, for example, suspension, solution and gas-phase processes. The polymerization reaction employing catalytic amounts of the above-described supported catalyst can be carried out under conditions well known in the art of Ziegler polymerization, for example, in an inert diluent at a temperature in the range of 50° C. to 120° C. and a pressure of 1 to 40 atmospheres in the gas phase at a temperature range of 70° C. to 100° C. at about 1 atmosphere to 50 atmospheres and upward. Illustrative of the gas-phase processes are those disclosed in U.S. Pat. No. 4,302,565 and U.S. Pat. No. 4,302,566, which references are hereby incorporated in their entirety by reference. As indicated above, one advantageous property of the catalyst system of this invention is the reduced amount of gas phase reactor fouling. The catalyst system can also be used to polymerize olefins at single phase conditions, i.e., 150° C. to 320° C. and 1,000-3,000 atmospheres. At these conditions the catalyst lifetime is short but the activity sufficiently high that removal of catalyst residues from the polymer is unnecessary. However, it is preferred that the polymerization be done at pressures ranging from 1 to 50 atmospheres, preferably 5 to 25 atmospheres. The catalyst system of this invention is highly responsive to hydrogen, allowing for the close control of molecular weight. Other well known weight controlling agents, such as diethyl zinc, may in addition be employed. The polymers prepared in accordance with this invention can be extruded, mechanically melted, cast or molded as desired. They can be used for plates, sheets, films, and a variety of other articles. While the invention is described in accordance with the specific examples below, it is understood that these are only for illustrative purposes. Many alternatives, modifications and variations will be apparent to those skilled in the art in the light of the below examples and as such will fall within the general scope of the claims. In the Examples following, the silica support was prepared by placing Davison Chemical Company MS 948 microspheroidal silica having a pore volume of 1.7 cc/g and a surface area of 335 m 2/ g in a vertical column and fluidizing with an upward flow of nitrogen. The column was heated from ambient temperature to 150° C. at the rate of 25° C./hr. The temperature was held at 150° C. for four hours. The column was then heated from 150° C. to the final temperature at the rate of 150° C./hr. The column was held at the final temperature for four hours. The column was then cooled under nitrogen. Fluorided silica was prepared in the same way except that the silica was dry mixed with ammonium silicofluoride prior to heating. The polymers produced by the catalyst of this invention are characterized as having "controlled" MWD. The polymer MWD is independently controlled by adjusting the amount of fluoride and the temperature to which the support and the fluorine containing compound are heated. In the examples that follow MWD is of critical importance. While it is possible to measure MWD directly, a less expensive but less direct method involving melt flow properties is used. Melt indices have successfully been used to characterize polymer MWD. Melt index ratio (MIR) is the quotient of two melt indices (MI), each measured at a different shear rate. The measurement of polymer MI's is described in ASTM D 1328. The method measures the rate of extrusion of a resin through an orifice of specified diameter and length at a fixed temperature and under a fixed load. The MI is inversely related to the polymer molecular weight because a higher molecular weight polymer will flow less readily than a lower molecular weight polymer and thus will require greater shear forces to induce it to flow. Thus, a higher molecular weight polymer will have a lower MI. Ratios of pairs of MI's measured at different loadings are used to characterize the polymer's shear response with lower MIR's indicating narrower MWD's. EXAMPLES 1-3 Examples 1-3 illustrate the performance of known supported vanadium catalysts which do not incorporate the MWD regulating mechanisms of the instant invention. Specifically, Examples 1-3 relate to catalyst components produced with supports which have not been fluorided. Preparation of Catalytic Component The silica support was dehydrated by heating as described above without the addition of fluoriding agents. The catalyst component was prepared by suspending about 2 g of the support in about 30 cc of isopentane. A solution of VOCl 3 in hexane (0.7 millimoles V/cc) was slowly added to the slurry while stirring to load 0.42 millimole V/g support. After 30 minutes of stirring, sufficient isobutylaluminum dichloride (25 wt% in heptane) was added slowly to the slurry while stirring to load 0.75 millimole Al/g support. After 30 minutes of stirring, sufficient silicon tetrachloride was added slowly while stirring to load 2.8 millimoles Si/g support. After 30 minutes of stirring, the slurry was residue dried under a nitrogen purge to constant weight at a final temperature of 50°-55° C. using an oil bath. Polymerization Polymerization of ethylene took place in a bench scale reactor using 1,000 cc isobutane as the diluent. 1.5 cc Freon-11 was used as the promoter and 2.4 millimoles TEAL as the cocatalyst. Polymerization temperature was 80° C. and polymerization time was 40 minutes. The concentration of ethylene used was 1.16 molar, the hydrogen to ethylene molar ratio was 0.026, and the hexene-1 to ethylene molar ratio was 0.36. The relatively large charge of hexene-1 was used to approximate the resin densities needed for film applications. Unfluorided silica supports were prepared for Examples 1, 2, and 3 by dehydrating at 300° C., 500° C., and 800° C., respectively. The polymerization results are shown in the first three columns of Table 1. Comparison of the three unfluorided examples shows that the dehydration temperature has little or no effect on resin melt flow properties. No effect on catalyst productivity was found at 500° C. and 800° C. Lower productivity was observed when the catalyst was supported on the silica which had been dehydrated at 300° C. This was expected in view of the high hydroxyl content of the support and the known sensitivity of the Ziegler-Natta catalysts to acidic hydrogen. EXAMPLES 4-7 Examples 4-6 illustrate the performance of catalyst which incorporates the MWD regulating mechanisms of the invention. Specifically, Examples 4-6 relate to catalyst components produced with supports which have been fluorided. Preparation of Catalytic Component The silica support was heated as described for Examples 1-3 following the addition and stirring of ammonium silicofluoride into the support. The mixture prior to dehydration was 2 wt% ammonium silicofluoride. The catalyst component was prepared as in Examples 1-3. Polymerization Polymerization of ethylene took place in a bench scale reactor as for Example 1-3. The molar concentration of ethylene, the hydrogen to ethylene molar ratio, and the hexene-1 to ethylene ratio were the same as in Examples 1-3. Fluorided silica supports were prepared for Examples 4, 5, 6, and 7 by dehydrating at 350° C., 500° C., 650° C., and 800° C., respectively. The polymerization results are shown in the last four columns of Table 1. Comparison of the four fluorided examples shows that the dehydration temperature has marked effect on productivity. Productivity increased from 79 g PE/g catalyst for dehydration at 350° C. (Example 4) to 139 g PE/g catalyst for dehydration at 800° C. (Example 7). The productivity for the fluorided catalyst dehydrated at 350° C. (Example 4) approximately equalled the productivity of the unfluorided catalyst dehydrated at 500° C. and 800° C., Examples 2 and 3, respectively. It is also to be noted that resin properties changed dramatically with fluorination temperature. Melt indices (MI) increased approximately three orders of magnitude and melt index ratios (MIR) decreased by one order of magnitude. This is in sharp contrast with the melt indices for the unfluorided catalyst (Examples 1-3) which generally decreased with increasing dehydration temperature. A comparison of Examples 1-7 also shows that the fluorided supports produced resin with lower density. TABLE 1__________________________________________________________________________ UNFLUORIDED SILICA FLUORIDED SILICA EXAMPLE 1 2 3 4 5 6 7__________________________________________________________________________Dehydration/Fluorination 300 500 800 350 500 650 800Temp. (°C.)PE Yield (g) 50 75 78 79 99 88 139Reactivity (kg/PE/gV · hr · C.sub.2) 39 59 61 61 77 68 108Melt Index2.1 kg 0.68 0.08 0.24 0.21 3.40 10.2 135 5 kg 3.35 0.43 1.28 1.14 18.0 48.0 514 21 kg 99.5 15.3 41.9 35.3 329 632 2055Melt Index Ratio21/2.1 146 191 175 168 97 62 1521/5 29.7 35.6 32.7 31.0 18.3 13.2 4.0Resin Density (g/cc) 0.9483 0.9482 0.9490 0.9474 0.9478 0.9400 0.9414__________________________________________________________________________ EXAMPLES 8-15 Examples 8-15 illustrate the effect of fluoriding the catalyst supports and the dependence of catalyst performance on the fluorination temperature. Preparation of Catalytic Component The silica support in Examples 8-10 were dehydrated by heating as described above without the addition of fluoriding agents. The catalyst components for Examples 8 and 9 were prepared as described in Examples 1-3 above. The catalyst component for Example 10 was similarly prepared but with higher loadings. Specifically, the catalyst in Example 10 was loaded to 0.77 millimoles V, 1.34 millimole Al, and 4.8 millimole Si/g support. The fluorided supports (Examples 11-15) were prepared as in Examples 4-7 above. The catalyst was made as described in Examples 4-7 above. Polymerization Polymerization of ethylene took place in bench scale reactors using 1,000 cc isobutane as the diluent. Polymerization temperature was 80° C. and polymerization time was 40 minutes. Promoter and cocatalyst were the same as previous examples. The molar concentration of ethylene used was 1.17, the hydrogen to ethylene molar ratio was 0.039, and the hexene-1 to ethylene ratio was 0.080. The relatively small charge of hexene-1 was used to approximate the resin density needed for blow molding applications. Unfluorided silica supports were prepared for Examples 8, 9 and 10 by dehydrating at 500° C. The polymerization results are shown in Table 2. Note that Examples 8 and 9 are duplicates of each other and serve to give some idea of the reproducibility of the results. Comparison of the three unfluorided examples with the five fluorided examples (Examples 11-15) shows that the fluorided catalysts have higher productivity. At a dehydration temperature of 500° C. (Example 13), the productivity of the fluorided catalyst is much higher than for the corresponding unfluorided catalysts (Examples 8-9), and significantly higher than for the more heavily loaded catalyst of Example 10. Further comparison of the three unfluorided examples with the five fluorided examples (Examples 11-15) shows that while the unfluorided catalysts gave resins with melt indices at 21 kg (I 21 ) of 33-155 and MIR's (I 21 /I 2 .1) of 235-168, the fluorided catalysts had corresponding values of 56-373 and 150-79, respectively. The fluorided catalyst thus are capable of producing resin with lower MIR's, which are indicative of narrower MWD's. TABLE 2__________________________________________________________________________ UNFLUORIDED SILICA FLUORIDED SILICA EXAMPLE 8 9 10 11 12 13 14 15__________________________________________________________________________Dehydration/Fluorination 500 500 500 350 450 500 650 800Temp. (°C.)PE Yield (g) 66 55 79 68 82 106 93 167Reactivity (kg/PE/gV · hr · C.sub.2) 51 43 34 53 64 82 72 130Melt Index2.1 kg 0.14 0.28 0.92 0.72 0.35 1.42 3.34 4.66 5 kg 0.89 1.66 5.38 5.94 2.06 7.56 17.6 22.12.1 kg 32.9 55.3 155 108 56.4 167 373 368Melt Index Ratio21/2.1 235 200 168 150 161 118 111 7921/5 37.0 33.3 28.8 18.2 27.4 22.1 21.2 16.6Resin Density (g/cc) 0.9584 0.9589 0.9587 0.9577 0.9572 0.9589 0.9609 0.9613__________________________________________________________________________ EXAMPLES 16-21 Examples 16-21 illustrate the effect of the amount of fluorination applied to the catalyst supports. Preparation of Catalytic Component The silica support for Example 16 was dehydrated as described above to a temperature of 800° C. The silica support for Examples 17-21 were fluorinated by heating as described above to a temperature of 650° C. in the presence of various amounts of ammonium silicofluoride, ranging from 0.5 to 3.0 wt%, or 0.3 to 1.8 wt% F added. The catalyst components for Examples 16-21 were prepared as described in Examples 4-7 above. The catalyst was made as described in Examples 4-7 above. Polymerization Polymerization of ethylene took place in a bench scale reactor using 1,000 cc isobutane as the diluent. Polymerization temperature was 80° C. and polymerization time was 40 minutes. Promoter and cocatalyst were the same as previous examples. The molar concentration of ethylene used was 1.25, the hydrogen to ethylene molar ratio was 0.014, and the hexene-1 to ethylene molar ratio was 0.33. An examination of the results shown in Table 3 shows that catalyst productivity does not appear to be affected at 0.5 wt% ammonium silicofluoride (ASF) loading but that a noticeable increase does occur at and above the 1.0 wt% level. However, the fluorination effect on catalyst hydrogen response and comonomer response is immediate as indicated by the higher MI's and lower resin density of Example 17 versus Example 16. TABLE 3__________________________________________________________________________ EXAMPLE 16 17 18 19 20 21__________________________________________________________________________ASF Added (wt %) 0 0.5 1.0 1.5 2.0 3.0F Measured (wt %) 0.013 0.42 0.67 0.94 1.1 0.84PE Yield (g) 59 62 70 84 133 133Productivity 46 48 54 65 103 103(kg PE/gV · hr · C.sub.2)Melt Index2.1 kg 0.034 0.26 0.72 0.82 1.57 1.10 5 kg 0.19 1.36 3.82 4.16 7.86 5.7 21 kg 6.09 38.4 96.0 89.0 157 131Melt Index Ratio21/2.1 179 148 133 108 103 11921/5 32.0 28.2 25.1 21.4 20.0 23.0Resin Density (g/cc) 0.9452 0.9414 0.9383 0.9350 0.9390 0.9409__________________________________________________________________________ The principle of the invention, detailed descriptions of specific applications of the principle, and the best mode in which it is contemplated to apply that principle have been described. It is to be understood that the foregoing is illustrative only and that other means and techniques can be employed without departing from the true scope of the invention defined in the following claims.
A vanadium catalyst component for the polymerization of 1-olefins and a process for making said catalyst component are disclosed. The catalyst component is prepared by fluoriding a support comprising silica. Use of the catalyst component provides a catalyst with increased activity, increased response to hydrogen for chain termination, increased response to comonomer for resin density reduction, and allows the molecular weight distribution of the polymers to be independently controlled by controlling the amount of fluorination and the fluorination temperature.
Identify and summarize the most critical features from the given passage.
[ "This application is a continuation-in-part of application Ser.", "No. 430,696 filed 11/1/89, now abandoned.", "BACKGROUND OF THE INVENTION 1.", "Field of the Invention This invention relates to a catalyst component and a process for preparing said catalyst component.", "The catalyst component may be employed with or without a cocatalyst in the polymerization of olefins to polyolefins.", "The process for preparing the catalyst component comprises the fluoriding of a support and further reaction of the support with a vanadium compound to produce a novel catalyst component which allows the molecular weight distribution of the polyolefins to be controlled by controlling the amount of fluorination and the fluorination temperature.", "Description of the Prior Art The use of vanadium-based catalysts in the polymerization of olefins is well known.", "When unsupported, vanadium catalysts usually assume the form of an oil or gum, and tend to cause fouling of the polymerization reactor.", "As a consequence, unsupported vanadium-based catalysts are unsuitable for use in a slurry or gas phase reaction process.", "Supported vanadium catalysts suffer from the fouling problem to a lesser degree.", "However supported vanadium catalysts suffer from a series of shortcomings.", "First, supported vanadium catalysts tend to produce polymers having too broad molecular weight distributions (MWD), with the polymer including a significant amount of low molecular weight oligomers.", "These oligomers, when present in polymers used in the manufacture of blow molded articles, produce an unacceptable amount of smoke.", "It would be highly desirable to have a supported vanadium catalyst which could be used in a gas or slurry phase polymerization process to produce polymer of narrower MWD for use in blow molding resin.", "Similarly, narrow MWD's are desirable for resin applications such as injection molding or linear low density polyethylene (LLDPE) film production.", "For other applications, such as the manufacture of high density polyethylene (HDPE) films, it would be desirable to produce a high molecular weight resin having a broad MWD.", "In yet other applications, such as wire and cable coatings manufacture, it is desirable for the resin to have a MWD of intermediate breadth.", "It would thus be desirable to have a supported vanadium catalyst for the production of high molecular weight polyolefins having an easily and accurately controllable MWD ranging from broad to narrow, as desired, depending on the intended use of the resin product.", "A clear need exists in the industry for a supported vanadium catalyst which can be tailored to provide resins of a specific MWD over a wide molecular weight range.", "A second shortcoming of supported vanadium catalysts is that these catalysts, when used in the polymerization of ethylene or in the copolymerization of ethylene with other 1-olefins, exhibit low activity in comparison to supported titanium-based catalysts.", "It would thus be desirable to have a supported vanadium catalyst which would have increased activity.", "A third shortcoming of supported vanadium catalysts is their need for relatively high levels of hydrogen during polymerization to control resin molecular weight.", "It would be desirable to have a supported vanadium catalyst that would have increased response to hydrogen for affecting chain termination and controlling molecular weight.", "Finally, supported vanadium catalysts require relatively high levels of comonomer to prepare medium and low density resins.", "It would be desirable to have a supported vanadium catalyst which would have increased response to comonomer to effect resin density reduction.", "Good comonomer utilization means that less comonomer is needed to give the target resin density.", "This is important for both slurry and gas phase polymerization since large amounts of comonomer lead to upsets in process conditions by increasing the solubilizing power of the slurry diluent or forming droplets in the gas phase.", "It is well known that fluorided supports can be used to advantage with chromium catalysts.", "In that context, fluorination increases chromium catalyst activity, narrows resin MWD, but decreases resin melt indices.", "Decreases in resin melt index (MI) are indicative of increased molecular weight and decreased response of the catalyst to hydrogen.", "Fluorination of chromium catalyst supports was disclosed in U.S. Pat. Nos. 2,825,721, and 2,951,816.", "U.S. Pat. No. 3,130,188 described the use of ammonium silicofluoride in conjunction with supports for chromium-based catalysts.", "U.S. Pat. No 4,011,382 discloses a titanated and fluorided support for a chromium catalyst and notes that increasing the fluorine content, while improving the rate of incorporation of comonomer, also decreases the resin melt index.", "Similarly, U.S. Pat. No. 4,077,904 describes a fluorided silica support for a chromium catalyst.", "The data show that fluorination decreased resin melt index and had no effect on MIR, i.e. that the average molecular weight increased while the MWD distribution remained unchanged.", "The earliest mention of a vanadium compound associated with fluorine for olefin polymerization is in U.S. Pat. No. 3,304,295 in connection with an unsupported catalyst mixture U.S. Pat. No. 4,262,105 discloses the fluorination of support material consisting of magnesium compounds for TiCl 4 catalysts for the polymerization of ethylene.", "U.S. Pat. No. 3,936,431 covers fluorided alumina-silica and alumina-calcium oxide as supports.", "Similarly, U.S. Pat. No. 4,258,159 discloses fluorided alumina and magnesium chloride as supports for titanium alkoxide catalysts.", "U.S. Pat. No. 4,359,403 teaches the addition of fluorine-containing compounds to silica prior to or during heating for the sole purpose of improving the activity of the silica supported catalyst.", "The catalyst is prepared by reacting the fluorided silica with a magnesium compound and then with the active metal.", "The patent also teaches the addition of alcohol for the purpose of improving the catalyst response to hydrogen.", "No mention is made of improved hydrogen response or comonomer response caused by the fluorination, nor is any mention made of the ability to control molecular weight distribution through independent control of the amount of fluorination and the fluorination temperature.", "SUMMARY OF THE INVENTION This invention discloses a novel vanadium-based catalyst component and a method for producing said catalyst component.", "The catalyst component, when used alone or in conjunction with a cocatalyst, provides a catalyst system having unique properties for olefin polymerization, including increased catalytic activity, increased response to hydrogen for chain termination, and increased response to comonomer for controlling resin density.", "The catalyst system of the invention provides the ability to control the molecular weight distribution through independent control of the amount of fluorination and the temperature at which the support is fluorinated.", "While fluorination of supports for vanadium-based catalysts, as taught by the present invention has the effect of increasing catalyst activity and narrowing MWD's, fluorination also, unexpectedly, has the effect of increasing resin melt indices, i.e. increasing hydrogen response.", "In addition, fluorination in accordance with the present invention decreases resin density which is indicative of increased comonomer response.", "In view of the high activity of the catalyst system of this invention it is generally not necessary to deash the polymer product since it will generally contain lower amounts of catalyst residues than polymer product produced in the presence of conventional catalyst.", "The ability of this catalyst system to control the MWD of the polymer product through fluorination substantially eliminates the formation of low weight oligomer thereby reducing the amount of smoke and facilitating the use of a polyolefin resin produced by the catalyst system as a blow molding resin.", "Moreover, the flexibility provided by this catalyst in allowing the tailoring of the breadth of the MWD over a wide range of molecular weights by varying the extent of fluorination and/or the fluorination temperature, permits the production of polymers having properties optimally suited for specific applications.", "The catalyst component disclosed in this invention may be used alone or in combination with an alkyl aluminum cocatalyst under conditions characteristic of Ziegler polymerization.", "The process for producing this novel catalyst component comprises the steps of dry mixing a support material with a fluorine compound.", "The mixture is then heated to some desirable fluorination temperature.", "Next, the support material is treated with a vanadium compound.", "The catalyst component of this invention may be used to produce polymer having a desired MWD by judiciously selecting the fluorine content and the fluorination temperature.", "The support material is selected from the group consisting of silica, alumina, silica-alumina mixtures, talc, zirconia, thoria, and metal oxides from the metals of Group IIA, IVA and IVB of the Periodic Table of the Elements.", "The fluorine compound is selected from the group consisting of (NH 4 ) 2 SiF 6 , NH 4 F, NH 4 HF, NH 4 BF 4 , KF, AlF 3 , HF, Zn(BF 4 ) 2 , Ni(BF 4 ) 2 , Sn(BF 4 ) 2 , (NH 4 ) 2 TiF 6 and the like.", "The disclosed catalyst may be employed, either by itself or in conjunction with a cocatalyst, in the gas phase, high pressure, solution, or slurry processes for the production of polyolefin resins.", "The catalyst may be usefully employed in the polymerization of ethylene and other alpha-olefins, particularly alpha-olefins having from 3 to 8 carbon atoms and in the copolymerization of these with other 1-olefins or diolefins, such as propylene, butene, pentene and hexene, butadiene, 1,4-pentadiene, and the like, so as to form copolymers of low and medium densities.", "The catalyst is particularly useful for the polymerization of ethylene and the copolymerization of ethylene with other alpha-olefins in gas phase processes to produce HDPE or LLDPE.", "DESCRIPTION OF THE PREFERRED EMBODIMENTS The catalyst component of the present invention comprises the solid reaction product of (A) a fluorine compound in the presence of an inert support material, (B) a vanadium compound, (C) an optional halogenating agent, and (D) an optional reducing agent.", "The catalyst component may optionally be reacted with (E) an organoaluminum compound cocatalyst to form a catalyst system.", "In accordance with this invention, the order of addition of ingredients in forming the vanadium containing catalyst can vary.", "In a preferred embodiment of this invention, after the inert support material is treated with the fluorine compound, the next substantial reaction of the fluorided support material should be conducted with the vanadium compound.", "In this embodiment, where there is no substantial reaction between the fluorided support material and any other catalyst component prior to the reaction with the vanadium compound, the catalyst produced has the unexpected effect of increasing the melt indices of the resulting polymer.", "It is not necessary in the preparation of the catalyst of this preferred embodiment for there to be complete isolation of the fluorided support from other catalyst components prior to contact between the fluorided support and the vanadium compound.", "It is only necessary that, at the time of addition of the vanadium compound, there should be enough remaining increased activity from the fluorination of the support so that the vanadium compound, and not some other catalyst component, will have substantial benefit of the fluorination of the support.", "Therefore, it is within the scope of this invention, that some catalyst components may be contacted with the fluorinated support in small reactive quantities prior to contact with the vanadium compound, as long as all of the benefits of fluorination are not used up prior to contact with the vanadium compound.", "In the preferred embodiment of this invention, the silica support material is dry mixed with the ammonium silicofluoride fluorine compound.", "Both the silica and the ammonium silicofluoride are solid particulates.", "Dry mixing is accomplished by simply blending the two solids.", "Alternatively, the fluorine compound could be dissolved in water and sprayed onto the dry silica, or the fluorine compound could be dissolved in water and added to an aqueous suspension of the silica, or the dry fluorine compound could be added to an aqueous suspension of the silica.", "However, when the fluorine compound is a solid particulate, dry blending is preferred.", "The mixture is then heated to a desirable temperature.", "The amount of fluorine used and the temperature to which the mixture is raised influence the narrowness of the MWD of the polymers formed using the catalyst of this invention.", "The support material can be any of the solid particulate porous supports such as talc, silica, zirconia, thoria, magnesia, and titania.", "Preferably the support material is a Group IIA, IIIA, IVA and IVB oxide in finely divided form.", "Suitable inorganic oxide materials which are desirably employed in accordance with this invention include silica, alumina, and silica-alumna and mixtures thereof, with silica being most preferred.", "Other inorganic oxides that may be employed either alone or in combination with the silica, alumina, or silica-alumina are magnesia, titania, zirconia, and the like.", "The preferred fluorine compound is ammonium silicofluoride (ASF), (NH 4 ) 2 SiF 6 , but many other fluorine containing compounds may be used.", "Among the fluorine compounds which may be used are hydrogen fluoride, HF, fluorides of ammonium and metals, such as KF, KF.", "HF, NH 4 F, NH 4 F.HF, AlF 3 , complex fluorides of ammonium and metals, Sn(BF 4 ) 2 and the like.", "The fluorine treated support, slurried in a hydrocarbon, is treated with a vanadium compound.", "The preferred vanadium compounds which may be usefully employed in the preparation of the catalyst component of this invention are well known in the art and may be represented by the formulas: ##STR1## where "x"", "is a number from 0 to 3 and R is a hydrocarbon radical (2) VCl y (OR) 4-y where "y"", "is a number from 3 to 4 and R is a hydrocarbon radical (3) ##STR2## where "z"", "is a number from 2 to 3 and (AcAc) is an acetyl acetonate group, (4) ##STR3## where (AcAc) is an acetyl acetonate group, and (5) VCl 3 .", "nL where "n"", "is a number from 2 to 3 and L is a Lewis base, such as tetrahydrofuran, which can form hydrocarbon-soluble complexes with VCl 3 .", "In formulas (1) and (2) above, R preferably represents a C 1 to C 8 aliphatic radical free of aliphatic unsaturation or an aromatic hydrocarbon radical such as a straight or branched alkyl, aryl, cycloalkyl, alkanyl, or aralkyl group, such as methyl, ethyl, propyl, isopropyl, butyl, n-butyl, i-butyl, t-butyl, pentyl, hexyl, cyclohexyl, octyl, benzyl, dimethyl, phenyl, naphthyl, and the like.", "Illustrative, but not limiting examples of the vanadium compounds are vanadyl trichloride, vanadium tetrachloride, vanadium tetrabutoxide, alkoxy vanadium chloride, vanadium trichloride, vanadyl acetylacetonate, vanadyl dichloroacetylacetonate, vanadyl chlorodiacetylacetonate, vanadium trichloride complexed with tetrahydrofuran, vanadyl tribromide, vanadium tetrabromide, and the like.", "The vanadium compound is preferably added to the reaction mixture in the form of a solution.", "The solvent can be any of the well-known inert hydrocarbon solvents such as hexane, heptane, benzene, toluene, and the like.", "In accordance with this invention, the optional halogenating agents are employed to obtain increased catalytic activity.", "The halogenating agents may be used to increase activity without detrimentally affecting the molecular weight distributions obtainable in accordance with this invention in which the content of the oligomer is reduced.", "The halogenating agents which can be employed are chlorinating, brominating and iodinating agents.", "The halogenating agents are desirably strong halogenating agents although weaker halogenating agents may be used.", "The halogenating agents can be liquid or gaseous under the reaction conditions.", "Illustrative but non-limiting examples of the strong halogenating agents that can be usefully employed in accordance with this invention are the silicon halides and the hydrocarbyl halides.", "The silicon halides can be represented by the formula X a SiR b s in which X is a halogen, R s is hydrogen, alkyl, cycloalkyl or aryl radical containing 1 to 20 carbon atoms, "a"+"b"=4 and "a"", "is at least 1.", "Illustrative examples of the silicon compounds are silicon tetrachloride, silicon tetrabromide, chlorosilanes such as, for example, trichlorosilane, trimethylchlorosilane, dimethyldichlorosilane, ethyltrichlorosilane, diethyldichlorosilane, dichlorodibutylsilane, trichlorobutylsilane, tribromobutylsilane, bromotrimethylsilane, and the like.", "Other halogenating agents are the hydrocarbyl halides which include carbon tetrachloride, chloroform, 1,1,1-trichloroethane, dichloromethane, trichlorofluormethane, and the like.", "The preferred halogenating agents are strong activating chlorinating agents, among which the most preferred are silicon tetrachloride, trichlorofluoromethane, trichloroethane, and the like.", "Illustrative of weak activating chlorinating agents are the thionyl halides, such as SOCl 2 .", "The halogenating agent may be conveniently added to the reaction slurry consisting of the reaction product of the fluorided support material, the vanadium compound, and the organoaluminum compound.", "The halogenating agent may be added as a pure compound or in the form of a solution with an inert solvent such as, for example, an aliphatic hydrocarbon solvent or an aromatic hydrocarbon solvent, or int may be added as a gas.", "The slurrying of the support material, as mentioned above, is conducted in an inert solvent.", "The inert solvent can be the same as that employed to dissolve the individual ingredients prior to the treatment step.", "Preferred solvents include mineral oils and the various hydrocarbons which are liquid at reaction temperatures and in which the individual ingredients are soluble.", "The amount of solvent used is not critical.", "The amount employed should, however, be sufficient to provide adequate capability for heat transfer away from the catalyst components during reaction and to permit good mixing.", "The catalyst component may optionally be reacted with a reducing agent.", "The reducing agent can be represented by the general formula R'", "m AlX 3-m wherein R'", "represents an alkyl group, cycloalkyl group or aryl group, X represents a halogen atom and "m"", "represents a suitable numeral equal to or greater than 1 and less than or equal to 3, or mixtures or complex compounds thereof.", "In particular, it is preferable to employ alkyl aluminum halide compounds wherein the alkyl groups have from 1 to 18 carbon atoms, preferably 1 to 9 carbon atoms and the halogen is chlorine.", "Illustrative but non-limiting examples of the organoaluminum compounds which may be suitably employed are the trialkylaluminums such as trimetylaluminum, triethylaluminum, tributylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, and the like.", "Illustrative examples of the diaklyaluminum halides are diethylaluminum chloride, diethylaluminum fluoride, dimethylaluminum chloride, dibutylaluminum chloride, diethylaluminum bromide, diethyaluminum iodide and dibutylaluminum iodide.", "Examples of the monoalkylaluminum dihalides are methylaluminum dichloride, ethylaluminum dichloride, butylaluminum dichloride, isobutylaluminum dichloride, ethylaluminum dibromide, ethylaluminum diiodide, butylaluminum dibromide, and butylaluminum diiodide.", "Moreover, the sesquihalides can be suitably employed such as methylaluminum sesquichloride and ethylaluminum sesquichloride and the like.", "Preferably, isobutylaluminum dichloride is used.", "The alkylaluminum may conveniently be added to the agitated slurry containing the particulate supports in the form of a solution with a dry hydrocarbon such as hexane, benzene, toluene, and the like.", "Alternatively, the alkylaluminum may be added to the slurry in undiluted form.", "The amounts of catalytic ingredients employed in the preparation of the supported catalyst component can vary over a wide range.", "The fluorine containing compound is added to the support at a concentration of about 0.01 to 1.0 millimoles F/g of dried support, preferably in the range of about 0.1 to about 0.6 millimoles F/g of dried support and especially in the range of about 0.2 to 0.4 millimoles F/g of dried support.", "The precise amount of fluorine containing compound added directly affects the narrowness of the MWD of the resulting polyolefins formed using the catalyst and must be judiciously selected to effect MWD's of desired breadth.", "The reaction of the support material with the fluorine containing compound takes place at temperatures of from 200° C. to 1000° C., preferably from 350° C. to 800° C. The precise temperature to which the mixture is heated directly affects the narrowness of the MWD of the resulting polyolefins formed using the catalyst and must be judiciously selected to affect MWD's of desired narrowness.", "The vanadium compound is added to the slurry of inert support at a concentration of about 0.05 to 2.0 millimoles V/g of dried support, preferably in the range of about 0.1 to about 1.5 millimoles V/g of dried support and especially in the range of about 0.2 to 1.0 millimoles V/g of dried support.", "Generally, the reaction steps may be conducted at temperatures in the range of about -50° C. to about 150° C. Preferred temperature ranges are from about -30° C. to about 60° C. with -10° C. to about 50° C. being most preferred.", "The catalyst components prepared in accordance with this invention are usefully employed with cocatalysts well known in the art of the Ziegler catalysis for polymerization of olefins.", "Typically, the cocatalysts which are used together with the transition metal containing catalyst component are organometallic compounds of Group Ia, IIa and IIIa metals such as aluminum alkyls, aluminum alkyl hydrides, lithium aluminum alkyls, zinc alkyls, magnesium alkyls and the like.", "The cocatalysts preferably used are the organoaluminum compounds.", "The preferred alkylaluminum compounds are represented by the formula AlR'", "n X'", "3-n wherein R'", "is hydrogen, hydrocarbyl or substituted hydrocarbyl group and n is as defined herein above.", "Preferably R'", "is an alkyl group having from 2 to 10 carbon atoms.", "X'", "is halogen and preferably chlorine.", "Illustrative examples of the cocatalyst material are ethyl aluminum dichloride, ethyl aluminum sesquichloride, diethyl aluminum chloride, aluminum triethyl, aluminum tributyl, diisobutyl aluminum hydride, diethyl aluminum ethoxide and the like.", "Aluminum trialkyl compounds are most preferred with triisobutylaluminum and aluminum triethyl being highly desirable.", "Cocatalysts are added to the polymerization reactor at a molar ratio to V of about 50 to 250 however, greater or lesser amounts can be usefully employed.", "Preferably, the Al/V ratio is in the range of about 50 to about 150 and especially in the range of about 75 to 100.", "Improved yields can be further obtained by employing polymerization promoters (activators) in combination with the catalyst system of this invention.", "The polymerization activators, in accordance with this invention, are preferably chlorocarbon activators.", "The activators are generally added to the polymerization reactor as a separate component.", "However, in the alternative, the activator can be adsorbed onto the surface of the catalyst component of this invention.", "The activator serves to significantly increase the productivity of the catalyst.", "Illustrative but non-limiting examples of the chlorocarbons are CHCl 3 , CFCl 3 , CH 2 Cl 2 , ethyltrichloroacetate, methyltrichloroacetate, hexachloropropylene, butylperchlorocrotonate, 1,3-dichloropropane, 1,2,3-trichloropropane, and 1,1,2-trichlorotrifluoroethane, etc.", "The activators may be gases or liquids at the conditions of polymerization.", "The catalyst system comprising the organoaluminum cocatalyst and the vanadium-containing solid catalyst component of this invention is preferably employed for the polymerization of ethylene.", "However, this catalyst system can also be used to polymerize other alpha-olefins having from 3 to 20 carbon atoms, ethylene copolymers with other alpha-olefins or diolefins, and ethylene copolymers with other alpha-olefins or diolefins.", "The catalyst system may be usefully employed to produce polyethylene or copolymers of ethylene.", "The catalyst is especially useful for the preparation of resins for blown film and blow molding applications.", "The olefins can be polymerized in the presence of the catalysts of this invention by any suitable known process such as, for example, suspension, solution and gas-phase processes.", "The polymerization reaction employing catalytic amounts of the above-described supported catalyst can be carried out under conditions well known in the art of Ziegler polymerization, for example, in an inert diluent at a temperature in the range of 50° C. to 120° C. and a pressure of 1 to 40 atmospheres in the gas phase at a temperature range of 70° C. to 100° C. at about 1 atmosphere to 50 atmospheres and upward.", "Illustrative of the gas-phase processes are those disclosed in U.S. Pat. No. 4,302,565 and U.S. Pat. No. 4,302,566, which references are hereby incorporated in their entirety by reference.", "As indicated above, one advantageous property of the catalyst system of this invention is the reduced amount of gas phase reactor fouling.", "The catalyst system can also be used to polymerize olefins at single phase conditions, i.e., 150° C. to 320° C. and 1,000-3,000 atmospheres.", "At these conditions the catalyst lifetime is short but the activity sufficiently high that removal of catalyst residues from the polymer is unnecessary.", "However, it is preferred that the polymerization be done at pressures ranging from 1 to 50 atmospheres, preferably 5 to 25 atmospheres.", "The catalyst system of this invention is highly responsive to hydrogen, allowing for the close control of molecular weight.", "Other well known weight controlling agents, such as diethyl zinc, may in addition be employed.", "The polymers prepared in accordance with this invention can be extruded, mechanically melted, cast or molded as desired.", "They can be used for plates, sheets, films, and a variety of other articles.", "While the invention is described in accordance with the specific examples below, it is understood that these are only for illustrative purposes.", "Many alternatives, modifications and variations will be apparent to those skilled in the art in the light of the below examples and as such will fall within the general scope of the claims.", "In the Examples following, the silica support was prepared by placing Davison Chemical Company MS 948 microspheroidal silica having a pore volume of 1.7 cc/g and a surface area of 335 m 2/ g in a vertical column and fluidizing with an upward flow of nitrogen.", "The column was heated from ambient temperature to 150° C. at the rate of 25° C./hr.", "The temperature was held at 150° C. for four hours.", "The column was then heated from 150° C. to the final temperature at the rate of 150° C./hr.", "The column was held at the final temperature for four hours.", "The column was then cooled under nitrogen.", "Fluorided silica was prepared in the same way except that the silica was dry mixed with ammonium silicofluoride prior to heating.", "The polymers produced by the catalyst of this invention are characterized as having "controlled"", "MWD.", "The polymer MWD is independently controlled by adjusting the amount of fluoride and the temperature to which the support and the fluorine containing compound are heated.", "In the examples that follow MWD is of critical importance.", "While it is possible to measure MWD directly, a less expensive but less direct method involving melt flow properties is used.", "Melt indices have successfully been used to characterize polymer MWD.", "Melt index ratio (MIR) is the quotient of two melt indices (MI), each measured at a different shear rate.", "The measurement of polymer MI's is described in ASTM D 1328.", "The method measures the rate of extrusion of a resin through an orifice of specified diameter and length at a fixed temperature and under a fixed load.", "The MI is inversely related to the polymer molecular weight because a higher molecular weight polymer will flow less readily than a lower molecular weight polymer and thus will require greater shear forces to induce it to flow.", "Thus, a higher molecular weight polymer will have a lower MI.", "Ratios of pairs of MI's measured at different loadings are used to characterize the polymer's shear response with lower MIR's indicating narrower MWD's.", "EXAMPLES 1-3 Examples 1-3 illustrate the performance of known supported vanadium catalysts which do not incorporate the MWD regulating mechanisms of the instant invention.", "Specifically, Examples 1-3 relate to catalyst components produced with supports which have not been fluorided.", "Preparation of Catalytic Component The silica support was dehydrated by heating as described above without the addition of fluoriding agents.", "The catalyst component was prepared by suspending about 2 g of the support in about 30 cc of isopentane.", "A solution of VOCl 3 in hexane (0.7 millimoles V/cc) was slowly added to the slurry while stirring to load 0.42 millimole V/g support.", "After 30 minutes of stirring, sufficient isobutylaluminum dichloride (25 wt% in heptane) was added slowly to the slurry while stirring to load 0.75 millimole Al/g support.", "After 30 minutes of stirring, sufficient silicon tetrachloride was added slowly while stirring to load 2.8 millimoles Si/g support.", "After 30 minutes of stirring, the slurry was residue dried under a nitrogen purge to constant weight at a final temperature of 50°-55° C. using an oil bath.", "Polymerization Polymerization of ethylene took place in a bench scale reactor using 1,000 cc isobutane as the diluent.", "1.5 cc Freon-11 was used as the promoter and 2.4 millimoles TEAL as the cocatalyst.", "Polymerization temperature was 80° C. and polymerization time was 40 minutes.", "The concentration of ethylene used was 1.16 molar, the hydrogen to ethylene molar ratio was 0.026, and the hexene-1 to ethylene molar ratio was 0.36.", "The relatively large charge of hexene-1 was used to approximate the resin densities needed for film applications.", "Unfluorided silica supports were prepared for Examples 1, 2, and 3 by dehydrating at 300° C., 500° C., and 800° C., respectively.", "The polymerization results are shown in the first three columns of Table 1.", "Comparison of the three unfluorided examples shows that the dehydration temperature has little or no effect on resin melt flow properties.", "No effect on catalyst productivity was found at 500° C. and 800° C. Lower productivity was observed when the catalyst was supported on the silica which had been dehydrated at 300° C. This was expected in view of the high hydroxyl content of the support and the known sensitivity of the Ziegler-Natta catalysts to acidic hydrogen.", "EXAMPLES 4-7 Examples 4-6 illustrate the performance of catalyst which incorporates the MWD regulating mechanisms of the invention.", "Specifically, Examples 4-6 relate to catalyst components produced with supports which have been fluorided.", "Preparation of Catalytic Component The silica support was heated as described for Examples 1-3 following the addition and stirring of ammonium silicofluoride into the support.", "The mixture prior to dehydration was 2 wt% ammonium silicofluoride.", "The catalyst component was prepared as in Examples 1-3.", "Polymerization Polymerization of ethylene took place in a bench scale reactor as for Example 1-3.", "The molar concentration of ethylene, the hydrogen to ethylene molar ratio, and the hexene-1 to ethylene ratio were the same as in Examples 1-3.", "Fluorided silica supports were prepared for Examples 4, 5, 6, and 7 by dehydrating at 350° C., 500° C., 650° C., and 800° C., respectively.", "The polymerization results are shown in the last four columns of Table 1.", "Comparison of the four fluorided examples shows that the dehydration temperature has marked effect on productivity.", "Productivity increased from 79 g PE/g catalyst for dehydration at 350° C. (Example 4) to 139 g PE/g catalyst for dehydration at 800° C. (Example 7).", "The productivity for the fluorided catalyst dehydrated at 350° C. (Example 4) approximately equalled the productivity of the unfluorided catalyst dehydrated at 500° C. and 800° C., Examples 2 and 3, respectively.", "It is also to be noted that resin properties changed dramatically with fluorination temperature.", "Melt indices (MI) increased approximately three orders of magnitude and melt index ratios (MIR) decreased by one order of magnitude.", "This is in sharp contrast with the melt indices for the unfluorided catalyst (Examples 1-3) which generally decreased with increasing dehydration temperature.", "A comparison of Examples 1-7 also shows that the fluorided supports produced resin with lower density.", "TABLE 1__________________________________________________________________________ UNFLUORIDED SILICA FLUORIDED SILICA EXAMPLE 1 2 3 4 5 6 7__________________________________________________________________________Dehydration/Fluorination 300 500 800 350 500 650 800Temp.", "(°C.)PE Yield (g) 50 75 78 79 99 88 139Reactivity (kg/PE/gV · hr · C.sub[.", "].2) 39 59 61 61 77 68 108Melt Index2.1 kg 0.68 0.08 0.24 0.21 3.40 10.2 135 5 kg 3.35 0.43 1.28 1.14 18.0 48.0 514 21 kg 99.5 15.3 41.9 35.3 329 632 2055Melt Index Ratio21/2.1 146 191 175 168 97 62 1521/5 29.7 35.6 32.7 31.0 18.3 13.2 4.0Resin Density (g/cc) 0.9483 0.9482 0.9490 0.9474 0.9478 0.9400 0.9414__________________________________________________________________________ EXAMPLES 8-15 Examples 8-15 illustrate the effect of fluoriding the catalyst supports and the dependence of catalyst performance on the fluorination temperature.", "Preparation of Catalytic Component The silica support in Examples 8-10 were dehydrated by heating as described above without the addition of fluoriding agents.", "The catalyst components for Examples 8 and 9 were prepared as described in Examples 1-3 above.", "The catalyst component for Example 10 was similarly prepared but with higher loadings.", "Specifically, the catalyst in Example 10 was loaded to 0.77 millimoles V, 1.34 millimole Al, and 4.8 millimole Si/g support.", "The fluorided supports (Examples 11-15) were prepared as in Examples 4-7 above.", "The catalyst was made as described in Examples 4-7 above.", "Polymerization Polymerization of ethylene took place in bench scale reactors using 1,000 cc isobutane as the diluent.", "Polymerization temperature was 80° C. and polymerization time was 40 minutes.", "Promoter and cocatalyst were the same as previous examples.", "The molar concentration of ethylene used was 1.17, the hydrogen to ethylene molar ratio was 0.039, and the hexene-1 to ethylene ratio was 0.080.", "The relatively small charge of hexene-1 was used to approximate the resin density needed for blow molding applications.", "Unfluorided silica supports were prepared for Examples 8, 9 and 10 by dehydrating at 500° C. The polymerization results are shown in Table 2.", "Note that Examples 8 and 9 are duplicates of each other and serve to give some idea of the reproducibility of the results.", "Comparison of the three unfluorided examples with the five fluorided examples (Examples 11-15) shows that the fluorided catalysts have higher productivity.", "At a dehydration temperature of 500° C. (Example 13), the productivity of the fluorided catalyst is much higher than for the corresponding unfluorided catalysts (Examples 8-9), and significantly higher than for the more heavily loaded catalyst of Example 10.", "Further comparison of the three unfluorided examples with the five fluorided examples (Examples 11-15) shows that while the unfluorided catalysts gave resins with melt indices at 21 kg (I 21 ) of 33-155 and MIR's (I 21 /I 2 [.", "].1) of 235-168, the fluorided catalysts had corresponding values of 56-373 and 150-79, respectively.", "The fluorided catalyst thus are capable of producing resin with lower MIR's, which are indicative of narrower MWD's.", "TABLE 2__________________________________________________________________________ UNFLUORIDED SILICA FLUORIDED SILICA EXAMPLE 8 9 10 11 12 13 14 15__________________________________________________________________________Dehydration/Fluorination 500 500 500 350 450 500 650 800Temp.", "(°C.)PE Yield (g) 66 55 79 68 82 106 93 167Reactivity (kg/PE/gV · hr · C.sub[.", "].2) 51 43 34 53 64 82 72 130Melt Index2.1 kg 0.14 0.28 0.92 0.72 0.35 1.42 3.34 4.66 5 kg 0.89 1.66 5.38 5.94 2.06 7.56 17.6 22.12.1 kg 32.9 55.3 155 108 56.4 167 373 368Melt Index Ratio21/2.1 235 200 168 150 161 118 111 7921/5 37.0 33.3 28.8 18.2 27.4 22.1 21.2 16.6Resin Density (g/cc) 0.9584 0.9589 0.9587 0.9577 0.9572 0.9589 0.9609 0.9613__________________________________________________________________________ EXAMPLES 16-21 Examples 16-21 illustrate the effect of the amount of fluorination applied to the catalyst supports.", "Preparation of Catalytic Component The silica support for Example 16 was dehydrated as described above to a temperature of 800° C. The silica support for Examples 17-21 were fluorinated by heating as described above to a temperature of 650° C. in the presence of various amounts of ammonium silicofluoride, ranging from 0.5 to 3.0 wt%, or 0.3 to 1.8 wt% F added.", "The catalyst components for Examples 16-21 were prepared as described in Examples 4-7 above.", "The catalyst was made as described in Examples 4-7 above.", "Polymerization Polymerization of ethylene took place in a bench scale reactor using 1,000 cc isobutane as the diluent.", "Polymerization temperature was 80° C. and polymerization time was 40 minutes.", "Promoter and cocatalyst were the same as previous examples.", "The molar concentration of ethylene used was 1.25, the hydrogen to ethylene molar ratio was 0.014, and the hexene-1 to ethylene molar ratio was 0.33.", "An examination of the results shown in Table 3 shows that catalyst productivity does not appear to be affected at 0.5 wt% ammonium silicofluoride (ASF) loading but that a noticeable increase does occur at and above the 1.0 wt% level.", "However, the fluorination effect on catalyst hydrogen response and comonomer response is immediate as indicated by the higher MI's and lower resin density of Example 17 versus Example 16.", "TABLE 3__________________________________________________________________________ EXAMPLE 16 17 18 19 20 21__________________________________________________________________________ASF Added (wt %) 0 0.5 1.0 1.5 2.0 3.0F Measured (wt %) 0.013 0.42 0.67 0.94 1.1 0.84PE Yield (g) 59 62 70 84 133 133Productivity 46 48 54 65 103 103(kg PE/gV · hr · C.sub[.", "].2)Melt Index2.1 kg 0.034 0.26 0.72 0.82 1.57 1.10 5 kg 0.19 1.36 3.82 4.16 7.86 5.7 21 kg 6.09 38.4 96.0 89.0 157 131Melt Index Ratio21/2.1 179 148 133 108 103 11921/5 32.0 28.2 25.1 21.4 20.0 23.0Resin Density (g/cc) 0.9452 0.9414 0.9383 0.9350 0.9390 0.9409__________________________________________________________________________ The principle of the invention, detailed descriptions of specific applications of the principle, and the best mode in which it is contemplated to apply that principle have been described.", "It is to be understood that the foregoing is illustrative only and that other means and techniques can be employed without departing from the true scope of the invention defined in the following claims." ]
FIELD OF THE INVENTION [0001] The present invention relates to the production of food products, and more particularly to pet food teats, and methods of making the food products by extrusion of suitable grain. BACKGROUND OF THE INVENTION [0002] Pet foods for dogs and cats are typically prepared as either canned or dry meal type rations. These rations are commonly formulated from a combination of proteinaceous and farinaceous materials. Farinaceous materials are derived from various cereal grains, and proteinaceous materials are derived from either vegetable protein sources or from meat and/or meat by-products. It is also well known to add various nutritional supplements to both meal and canned rations such as vitamins, minerals, etc. [0003] Dry meal type rations typically have a cereal-like texture and a low moisture content around 10%. Dry rations can be produced to provide a completely balanced diet for an animal. Dry rations also have excellent storage characteristics, thus permitting use of relatively inexpensive packaging techniques. [0004] Canned rations have a meat-like texture and a high moisture content. The elevated moisture content of such canned foods requires thermal processing in sealed containers to obtain a commercially sterile product, thereby adding considerably to product costs. Once a can is opened, it must be quickly consumed since the high moisture content is conducive to supporting microbial growth, and hence the product will deteriorate rapidly unless stored in refrigerated conditions. [0005] A third type of animal food has become popular more recently which can be characterized as intermediate moisture products, typically having a moisture content in the range of about 15 to 30%. For these intermediate products, in order to prevent microbial decomposition, such products must be specially processed through pasteurization, or must be chemically treated with various preservatives, and/or must be packaged in sealed containers which are commercially sterilized. Another approach to preserving these intermediate moisture products is to disperse an aqueous phase of water-soluble solids throughout the product, the soluble solids being principally sugar at a level high enough to exert a bacteriostatic effect sufficient to stabilizing animal food. Like canned rations, these intermediate products are more expensive to produce because of the need to specially package or preserve the products. [0006] Conventional methods for producing dry rations involve either extrusion or pelletizing techniques wherein the dry rations are formed in a desired size and shape for a particular animal. The mixed farinaceous and/or proteinaceous sources of dry rations in extrusion are subjected to the action of the extruding machine which mixes the materials, and exposes them to heat and elevated pressures thereby converting the materials to a flowable semi-liquid substance. The temperature of the mixed materials passing through the extruder is typically above 212° F. The heated materials are expelled through die in the extruder device to atmospheric pressure, so that the heated moisture within the mixture flashes to steam causing the material to expand into a cellular mass. The cellular mass is then cut into pieces of a desired length, dried to a stable moisture content, and then treated with a flavored coating or with a chemical coating to preserve the product. The materials used to make most dry rations are also mixed prior to extrusion with various chemical preservatives to enhance the stability of the ration, and/or to assist in extrusion of the material. Although dry rations have a relatively long shelf life, depending upon the particular type of cereal grain or protein source used in the extrusion, there is still a need to preserve the ration with some type of chemical preservative. [0007] It is well known to use various types of cereal grains in an extrusion process to produce feed having characteristics reflective of the particular type of cereal grain which is used. One reference which discloses a method of making a pet snack food, to include disclosure of various of types of cereal grains which may be used to make pet food an extrusion process is the U.S. Pat. No. 5,894,029. [0008] Another reference disclosing animal feed which is produced through an extrusion process, and composed of proteinaceous and/or farinaceous material, is the U.S. Pat. No. 4,143,169. [0009] Among the cereal grains used for making pet food or pet treats, corn and wheat are perhaps the most well known. Other types of grains may be added in smaller portions to the larger portions of wheat or corn in those dry food rations which are made by extrusion. [0010] As pet food and pet food treats continue to develop in sophistication based upon a market which is increasingly conducive to sale of diversified pet products, new techniques for producing the pet foods also continue to develop. Despite pet food product diversification, basic food production still includes the need to provide healthy, inexpensive, and easily packaged food products. [0011] Sorghum Vulgare is perhaps the oldest domesticated plant known to man. It is has been hybridized since early Egyptian years and is very diversified in its hybrid state. Varieties commonly referred to as Milo have few if any uses other than for animal feed. Sorghum Vulgare is widely used in the United States as a less expensive feed grain in comparison to corn or wheat. Other parts of the world, particularly Africa and Asia, use Sorghum for flour and human food. In the United States, Milo as a particular group of hybrids, is a very different type of cereal grain as compared to Sorghum which is grown in other parts of the world. In the United States, a need was established early on for developing a feed grain that was resistant to various growing problems. These problems included drought, insect infestations, migrating birds, and high winds. As a result of these factors, Milo has evolved into special hybrids which are able to withstand the various growth problems. Accordingly, the type of Sorghum available particularly in the United States is a very successful grain, but is not well suited for any use other than standard feed grain. SUMMARY OF THE INVENTION [0012] One object of the present invention is to provide an animal food product which utilizes a grain which is inexpensive, easily extrudable, and has high nutrition value. [0013] Another object of the present invention to provide an animal food product which may readily accept a flavoring or additive prior to the extrusion process thereby eliminating the need for a separate processing step in incorporating the additive. [0014] It is yet another object of the present invention to provide an animal food product which may be varied in its texture, weight, size and density based upon the moisture content of the materials which are extruded to make the food product. [0015] It is yet another object of the present invention to provide an animal food product which has an extended shelf life, and does not require chemical preservatives in order to maintain the extended shelf life. [0016] It is yet another object of the present invention to provide a process for making an animal food product wherein the process may be easily adapted to produce animal food products of a desired size, density, weight, nutritional value and flavorings. [0017] The products of the present invention comprise a matrix preferably manufactured from Milo seeds which at least have been decorticated resulting in berry and berry particulates which may then be exposed directly to extrusion. Additives may be added to the processed Milo prior to extrusion. The additives may be nutritional supplements and/or specific flavorings which enhance the nutritional value and palatability of the product. [0018] In accordance with a first embodiment of the method of the present invention, a desired stock of Milo grain is chosen, and the selected grain is cleaned and sized. In the cleaning operation, a destoning operation may be incorporated to remove any hard material of like size and shape, such as small stones or pebbles. The Milo grain is then decorticated in one of several known methods of grain decorticating. The decortication removes the husks or hulls of the Milo seeds. Optionally, the remaining berry and berry particulates are then passed through a scourer to remove the fatty endogerm portion of the berries. De-fatting of the berries can enhance the ability of the Milo grain to be extruded because fat can act as a lubricant in extrusion thereby degrading the ability of an extruder to produce a consistent food product. [0019] The next step in production of the food is an extrusion wherein a baked-type extruder is used under preferred heat and pressure ranges. The product produced in the extrusion process can be defined as a matrix of Milo which may carry an additive such as flavorants. One advantage of extrusion is that it also serves to kill bacteria and other microbes thereby helping to provide a product of increased shelf life. One final step which may be required in the process is to cure the product, preferably at a room temperature with a minimum of 60% air moisture content, until the product is stable. This last curing step is affected by the type of additives which may be added to the matrix. [0020] In accordance with a second embodiment of the present invention, other types of grains or even tubers may be used to produce a desired food product wherein the method of production requires an additional step of removing the starch from the grain/tuber. Other grains which may be selected include corn, wheat, rice, and others. The extracted starch is the portion of the grain/tuber which is used, and the remaining portions are discarded. Typically, for starch based products which are extruded, flavorings are not added until after the extrusion process thereby increasing the complexity and overall cost of producing the food product. With the second embodiment of the present invention, this later flavor adding step can be eliminated by directly adding the flavorings prior to extrusion. In this second embodiment, an additional step is required which is to remove the starch from the rest of the grain or tuber, the removed starch typically being in a powdered form. The starch may be removed in any well-known starch removal process to produce a basic starch powder. [0021] Other features and advantages of the present invention will become apparent from a review of the following detailed description, taken in conjunction with the drawing, which illustrates the preferred embodiments of the method of the present invention. BRIEF DESCRIPTION OF THE DRAWING [0022] [0022]FIG. 1 is a flowchart showing the basic steps used in processing Milo grain to produce a food product according to the present invention. DETAILED DESCRIPTION [0023] Referring to FIG. 1, the basic steps in the methods of making the food product of the present invention is illustrated. In a first step at block 10 , a pure stock of grain Milo is selected. Although there is no specific hybrid of Milo which is required for the product and method of the present invention, it is desirable to choose a single pure stock grain because this pure stock grain is advantageous in creating repeatability of the extrusion process. Each hybrid of Milo may contain its own unique protein sequence. Even small differences in protein sequence may alter a particular extrusion. Therefore, by deliberately selecting grains with the same desired protein sequence, extrusion can be more reliably repeated. [0024] The next step in the process shown at block 12 is to clean and size the Milo grain. Standard cleaning and sizing equipment may be used to process the grain at this step wherein air/water streams may be used to clean the grain, and the grain may be passed through various sieves to obtain the desired grain size. There is no required grain size for the present invention, and it has been found in testing that many different grain sizes can be used with good extrusion results. [0025] Shown at block 14 is a next step in the process which is an optional destoning operation to remove stones or other similar sized objects which may still remain in the grain after cleaning and sizing. Although a destoning operation is shown as a separate optional step, destoning can be incorporated within a cleaning and sizing operation at step 12 . Therefore, it shall be understood that although destoning is shown separately in the flowchart, is not necessarily required to be a separate step in the method. Any well known destoning operation can be used. [0026] The next step in the process is shown at block 16 which is the decortication of the Milo grain. Any one of several methods of usual grain decortication may be used to decorticate the Milo. For example, two references which disclose methods for decorticating Milo and which have been found to be particularly effective are the methods described in the U.S. Pat. Nos. 5,713,526 and 5,820,039. These two references are incorporated herein by reference for purposes of disclosing basic methods by which Milo grain may be decorticated. Another common method of decortication involves swirling the grain in a cyclone at a high rate of speed against a rasping surface. The grain contacts the rasping surface and breaks into pieces wherein the lighter, less dense hull is separated from the berry. Yet another common method is to expose the Milo grain to a stream of high-pressure water which separates the berry from the hull of the grain. [0027] The next step in the method is shown at block 18 which is an optional step of scouring the grain to remove fatty oils or lipids. There are two distinct advantages for de-fatting the Milo grain at this stage. The first is enhancing the consistency and repeatability of the extrusion process because fats in the grain tend to act as a lubricant through the extrusion die, thereby degrading extruder operation. The second advantage is the production of a more nutritional pet food which has less fat content. Well-known grain scouring processes may be used to remove the fatty endogerm from the Milo grain. Although scouring is discussed as a step in the basic method, it shall be understood that scouring is not necessarily required as it may be desirable in some circumstances to have certain levels of fat within the food product. Additionally, scouring may be eliminated to simplify the overall food production process. [0028] The next step in the method is shown at block 20 which involves introduction of a desired additive(s) to the processed Milo. The Milo and additive(s) may be referred to as a grain mix. For pet food, there are a number of additives which are contemplated within the present invention which may be advantageous for pet food or pet treats. Examples of these additives include additives in the form of food meals which may be derived from vegetable or animal protein sources. More specifically, one particular type of meal may include a liver meal which is known to be preferred by almost all dogs. To create a pet treat incorporating this liver meal having a light and puffy texture, the mixture ratio of the Milo to the liver meal would be from about 7:1 to about 12:1 by weight. Preferably, the ratio of the Milo to the liver meal is about 9:1 by weight. In order to provide an extrudable mixture, it is preferable to maintain the Milo at or around 16% moisture, and the liver meal at or around 20% moisture. Alternatively, to produce a pet treat which is not as puffy but rather is denser, smaller, and has more of a crunchy, nugget consistency, the ratio of Milo to liver meal would be from about 1:2 to about 5:2 by weight. Preferably, the the ratio of Milo to liver meal would be about 3:2 by weight. For this denser product, the moisture content prior to extrusion is preferably about 18-22%. Other additives which may be used include vitamins, minerals or other nutritional supplements. These additives can be added at this step in prescribed amounts which do not pose a health risk to the animals even in the event that a particular animal would consume a large number of the treats at a single time. Other types of additives which are also contemplated include medications, peanuts, fish meal, poultry meal, dried fruits or vegetables, flavored oils or other concentrated liquid flavorants. Milo is a grain which readily accepts a variety of additives, and there is little if any segregation or separation between the Milo grain and the additives in the extruded food product. [0029] It may be desirable to mechanically mix the grain mix in a bin which will then meter the grain mix into the extrusion machine. Mechanical mixing helps to ensure uniform dispersion of the additive. It is also necessary to add water to the decorticated grain in order to create the grain mix with the necessary moisture content. It has been found in testing that Milo has approximately 10-12% moisture content prior to processing. In order to optimize extrusion, it has been found through testing that a moisture content of about 16% is preferable. [0030] The next step in the method is illustrated at block 22 which involves extrusion of the Milo grain mix. Through testing, it has been found that extrusion can be achieved utilizing a bake-type extruder which exposes the grain mix to heat in the range of about 325° F. to about 400° F., and pressure in the range of about 1500 psi to about 2,000 psi. The particular shape of the die used in the extruding machine may be adapted to produce a food product of a desired shape. One example of a die could include the use of a die having a round shaped hole with a diameter of approximately 0.120 inch. The cutting mechanism used in the extruding machine can be adapted for cutting the extrudate to a length of about three-quarters inch. For a grain mix which is extruded having an overall moisture content of approximately 16%, the resulting extruded product has a light, puffy and cellular consistency at moisture contents above about 18%. As moisture content is increased in the grain mix, the resulting food product is smaller and denser as the product will experience less expansion during extrusion. For example, a food product having a more nugget-like consistency can be produced which is still crunchy, but does not have the puffy, cellular consistency. Temperature and pressure can also be adjusted within the extrusion process to produce a food product which is of a desired size, shape and density. Generally, increasing temperature and pressure will increase the expansion of the grain mix during extrusion. [0031] The last step of the method is shown at block 24 which contemplates curing the food product to thereby stabilize the product prior to shipping. Depending upon the texture and consistency of the food product produced, i.e., one that is either puffed or more dense, a certain amount of curing may be required to allow the food product to reach equilibrium in terms of moisture content. [0032] There are a number of advantages of utilizing a Milo matrix as a food product. First, there is the relatively low cost of producing such a food product as the processing steps for creating the Milo matrix can be achieved within a relatively simple grain processing method. Milo grain is a relatively high protein, low fat grain which is both palatable and easily digestible by both humans and animals. Processed Milo is generally hydrophobic, therefore very stable in all climates and storing conditions. Accordingly, the food product produced may be packaged and sold within packaging which does not have to be sealed or otherwise specially treated. For example, large bins of the Milo food product can be directly incorporated within retail locations where a consumer measures a desired amount of the food product to be purchased and then places the product into a plastic or paper bag. A Milo food product made by the above-described method requires no chemical additives to preserve the product for extended shelf life. Another advantage as mentioned above is the ability to produce food products which have a variety of densities. Lighter, puffier products as well as denser, crunchier products may be easily produced. By varying the temperature and pressure of the extrusion, or adjusting the moisture content, the particular size and density of the product can be chosen. For example, extruding the Milo grain mix through a die having a round opening of about 0.120 of an inch in diameter and at about 16% moisture content, can produce a product having a width/diameter of approximately three-quarters inch, which then can also be cut to a desired length. Increasing the moisture to about 18% has been shown to produce a product having a width/diameter of approximately one-half inch. During the extrusion process, the heat and pressure advantageously kill bacteria and other undesirable microorganisms thereby increasing the shelf life of the product. Also during extrusion, the additives become evenly mixed within the decorticated grain thereby producing a homogeneous mixture. Accordingly, the additive is evenly distributed throughout each batch of the extruded pet food product in contrast to many other types of pet treats, into which flavorings or additives are incorporated by an electrostatic process which simply coats the exterior surface of the product. These methods of incorporating a flavoring/additive are less desirable because the flavoring/additive is more easily separated from the product. By creating a homogeneous mixture through the extrusion process of the present invention, the desired additive is better delivered to the consuming animal. [0033] In accordance with another preferred embodiment of the present invention, other types of grains may be used to produce the food product. For example, corn, wheat and rice can also be used as the basic grains which are processed in the present invention. With these grains; however, an additional processing step is required to remove the starch from the remaining part of the grain. The removed starch is typically in powder form. In their natural state, these other grains are very difficult to extrude successfully, and therefore, the part of the grain to be extruded, the amylose starch, is separated from the whole grain prior to extrusion. Milo also contains starch, best characterized as an amylose -pectin starch. However, after decortication, Milo is readily extrudable without also having to first isolate the starch component of the grain. [0034] In addition to grains in which starch has been removed for use in extrusion, it is also contemplated within the present invention to use the starch extracted from tubers, such as potatoes. As with the Milo grain, these extracted starches must also receive the required amount of water to raise the moisture content to a desired level corresponding to the texture and density of the final product. [0035] Referring again to FIG. 1, the additional step of separating the starch is shown at block 30 in dotted lines. Additives are added to the starch in step 20 , and then the mixture is extruded at step 22 . The final step again would be curing, as required, at step 24 . In accordance with another aspect of the invention, the grain mix can also be mixed with a gelatin prior to extrusion thereby increasing the hardness of the resulting extruded food product. [0036] The above invention has been described with respect to preferred embodiments; however, other changes and modifications may be made within the spirit and scope of the invention.
A food product and method of making the same are disclosed. The food product is preferably made of a processed Sorghum grain, and preferably from hybrids of Milo. The grain is subjected to decortication and extrusion. Additives may be provided to flavor or otherwise nutritionally enhance the processed Milo. The additives are added prior to extrusion. In another embodiment, the food product may be made from other grains or tubers by removing the starch and then using the starch to extrude the food product.
Concisely explain the essential features and purpose of the concept presented in the passage.
[ "FIELD OF THE INVENTION [0001] The present invention relates to the production of food products, and more particularly to pet food teats, and methods of making the food products by extrusion of suitable grain.", "BACKGROUND OF THE INVENTION [0002] Pet foods for dogs and cats are typically prepared as either canned or dry meal type rations.", "These rations are commonly formulated from a combination of proteinaceous and farinaceous materials.", "Farinaceous materials are derived from various cereal grains, and proteinaceous materials are derived from either vegetable protein sources or from meat and/or meat by-products.", "It is also well known to add various nutritional supplements to both meal and canned rations such as vitamins, minerals, etc.", "[0003] Dry meal type rations typically have a cereal-like texture and a low moisture content around 10%.", "Dry rations can be produced to provide a completely balanced diet for an animal.", "Dry rations also have excellent storage characteristics, thus permitting use of relatively inexpensive packaging techniques.", "[0004] Canned rations have a meat-like texture and a high moisture content.", "The elevated moisture content of such canned foods requires thermal processing in sealed containers to obtain a commercially sterile product, thereby adding considerably to product costs.", "Once a can is opened, it must be quickly consumed since the high moisture content is conducive to supporting microbial growth, and hence the product will deteriorate rapidly unless stored in refrigerated conditions.", "[0005] A third type of animal food has become popular more recently which can be characterized as intermediate moisture products, typically having a moisture content in the range of about 15 to 30%.", "For these intermediate products, in order to prevent microbial decomposition, such products must be specially processed through pasteurization, or must be chemically treated with various preservatives, and/or must be packaged in sealed containers which are commercially sterilized.", "Another approach to preserving these intermediate moisture products is to disperse an aqueous phase of water-soluble solids throughout the product, the soluble solids being principally sugar at a level high enough to exert a bacteriostatic effect sufficient to stabilizing animal food.", "Like canned rations, these intermediate products are more expensive to produce because of the need to specially package or preserve the products.", "[0006] Conventional methods for producing dry rations involve either extrusion or pelletizing techniques wherein the dry rations are formed in a desired size and shape for a particular animal.", "The mixed farinaceous and/or proteinaceous sources of dry rations in extrusion are subjected to the action of the extruding machine which mixes the materials, and exposes them to heat and elevated pressures thereby converting the materials to a flowable semi-liquid substance.", "The temperature of the mixed materials passing through the extruder is typically above 212° F. The heated materials are expelled through die in the extruder device to atmospheric pressure, so that the heated moisture within the mixture flashes to steam causing the material to expand into a cellular mass.", "The cellular mass is then cut into pieces of a desired length, dried to a stable moisture content, and then treated with a flavored coating or with a chemical coating to preserve the product.", "The materials used to make most dry rations are also mixed prior to extrusion with various chemical preservatives to enhance the stability of the ration, and/or to assist in extrusion of the material.", "Although dry rations have a relatively long shelf life, depending upon the particular type of cereal grain or protein source used in the extrusion, there is still a need to preserve the ration with some type of chemical preservative.", "[0007] It is well known to use various types of cereal grains in an extrusion process to produce feed having characteristics reflective of the particular type of cereal grain which is used.", "One reference which discloses a method of making a pet snack food, to include disclosure of various of types of cereal grains which may be used to make pet food an extrusion process is the U.S. Pat. No. 5,894,029.", "[0008] Another reference disclosing animal feed which is produced through an extrusion process, and composed of proteinaceous and/or farinaceous material, is the U.S. Pat. No. 4,143,169.", "[0009] Among the cereal grains used for making pet food or pet treats, corn and wheat are perhaps the most well known.", "Other types of grains may be added in smaller portions to the larger portions of wheat or corn in those dry food rations which are made by extrusion.", "[0010] As pet food and pet food treats continue to develop in sophistication based upon a market which is increasingly conducive to sale of diversified pet products, new techniques for producing the pet foods also continue to develop.", "Despite pet food product diversification, basic food production still includes the need to provide healthy, inexpensive, and easily packaged food products.", "[0011] Sorghum Vulgare is perhaps the oldest domesticated plant known to man.", "It is has been hybridized since early Egyptian years and is very diversified in its hybrid state.", "Varieties commonly referred to as Milo have few if any uses other than for animal feed.", "Sorghum Vulgare is widely used in the United States as a less expensive feed grain in comparison to corn or wheat.", "Other parts of the world, particularly Africa and Asia, use Sorghum for flour and human food.", "In the United States, Milo as a particular group of hybrids, is a very different type of cereal grain as compared to Sorghum which is grown in other parts of the world.", "In the United States, a need was established early on for developing a feed grain that was resistant to various growing problems.", "These problems included drought, insect infestations, migrating birds, and high winds.", "As a result of these factors, Milo has evolved into special hybrids which are able to withstand the various growth problems.", "Accordingly, the type of Sorghum available particularly in the United States is a very successful grain, but is not well suited for any use other than standard feed grain.", "SUMMARY OF THE INVENTION [0012] One object of the present invention is to provide an animal food product which utilizes a grain which is inexpensive, easily extrudable, and has high nutrition value.", "[0013] Another object of the present invention to provide an animal food product which may readily accept a flavoring or additive prior to the extrusion process thereby eliminating the need for a separate processing step in incorporating the additive.", "[0014] It is yet another object of the present invention to provide an animal food product which may be varied in its texture, weight, size and density based upon the moisture content of the materials which are extruded to make the food product.", "[0015] It is yet another object of the present invention to provide an animal food product which has an extended shelf life, and does not require chemical preservatives in order to maintain the extended shelf life.", "[0016] It is yet another object of the present invention to provide a process for making an animal food product wherein the process may be easily adapted to produce animal food products of a desired size, density, weight, nutritional value and flavorings.", "[0017] The products of the present invention comprise a matrix preferably manufactured from Milo seeds which at least have been decorticated resulting in berry and berry particulates which may then be exposed directly to extrusion.", "Additives may be added to the processed Milo prior to extrusion.", "The additives may be nutritional supplements and/or specific flavorings which enhance the nutritional value and palatability of the product.", "[0018] In accordance with a first embodiment of the method of the present invention, a desired stock of Milo grain is chosen, and the selected grain is cleaned and sized.", "In the cleaning operation, a destoning operation may be incorporated to remove any hard material of like size and shape, such as small stones or pebbles.", "The Milo grain is then decorticated in one of several known methods of grain decorticating.", "The decortication removes the husks or hulls of the Milo seeds.", "Optionally, the remaining berry and berry particulates are then passed through a scourer to remove the fatty endogerm portion of the berries.", "De-fatting of the berries can enhance the ability of the Milo grain to be extruded because fat can act as a lubricant in extrusion thereby degrading the ability of an extruder to produce a consistent food product.", "[0019] The next step in production of the food is an extrusion wherein a baked-type extruder is used under preferred heat and pressure ranges.", "The product produced in the extrusion process can be defined as a matrix of Milo which may carry an additive such as flavorants.", "One advantage of extrusion is that it also serves to kill bacteria and other microbes thereby helping to provide a product of increased shelf life.", "One final step which may be required in the process is to cure the product, preferably at a room temperature with a minimum of 60% air moisture content, until the product is stable.", "This last curing step is affected by the type of additives which may be added to the matrix.", "[0020] In accordance with a second embodiment of the present invention, other types of grains or even tubers may be used to produce a desired food product wherein the method of production requires an additional step of removing the starch from the grain/tuber.", "Other grains which may be selected include corn, wheat, rice, and others.", "The extracted starch is the portion of the grain/tuber which is used, and the remaining portions are discarded.", "Typically, for starch based products which are extruded, flavorings are not added until after the extrusion process thereby increasing the complexity and overall cost of producing the food product.", "With the second embodiment of the present invention, this later flavor adding step can be eliminated by directly adding the flavorings prior to extrusion.", "In this second embodiment, an additional step is required which is to remove the starch from the rest of the grain or tuber, the removed starch typically being in a powdered form.", "The starch may be removed in any well-known starch removal process to produce a basic starch powder.", "[0021] Other features and advantages of the present invention will become apparent from a review of the following detailed description, taken in conjunction with the drawing, which illustrates the preferred embodiments of the method of the present invention.", "BRIEF DESCRIPTION OF THE DRAWING [0022] [0022 ]FIG. 1 is a flowchart showing the basic steps used in processing Milo grain to produce a food product according to the present invention.", "DETAILED DESCRIPTION [0023] Referring to FIG. 1, the basic steps in the methods of making the food product of the present invention is illustrated.", "In a first step at block 10 , a pure stock of grain Milo is selected.", "Although there is no specific hybrid of Milo which is required for the product and method of the present invention, it is desirable to choose a single pure stock grain because this pure stock grain is advantageous in creating repeatability of the extrusion process.", "Each hybrid of Milo may contain its own unique protein sequence.", "Even small differences in protein sequence may alter a particular extrusion.", "Therefore, by deliberately selecting grains with the same desired protein sequence, extrusion can be more reliably repeated.", "[0024] The next step in the process shown at block 12 is to clean and size the Milo grain.", "Standard cleaning and sizing equipment may be used to process the grain at this step wherein air/water streams may be used to clean the grain, and the grain may be passed through various sieves to obtain the desired grain size.", "There is no required grain size for the present invention, and it has been found in testing that many different grain sizes can be used with good extrusion results.", "[0025] Shown at block 14 is a next step in the process which is an optional destoning operation to remove stones or other similar sized objects which may still remain in the grain after cleaning and sizing.", "Although a destoning operation is shown as a separate optional step, destoning can be incorporated within a cleaning and sizing operation at step 12 .", "Therefore, it shall be understood that although destoning is shown separately in the flowchart, is not necessarily required to be a separate step in the method.", "Any well known destoning operation can be used.", "[0026] The next step in the process is shown at block 16 which is the decortication of the Milo grain.", "Any one of several methods of usual grain decortication may be used to decorticate the Milo.", "For example, two references which disclose methods for decorticating Milo and which have been found to be particularly effective are the methods described in the U.S. Pat. Nos. 5,713,526 and 5,820,039.", "These two references are incorporated herein by reference for purposes of disclosing basic methods by which Milo grain may be decorticated.", "Another common method of decortication involves swirling the grain in a cyclone at a high rate of speed against a rasping surface.", "The grain contacts the rasping surface and breaks into pieces wherein the lighter, less dense hull is separated from the berry.", "Yet another common method is to expose the Milo grain to a stream of high-pressure water which separates the berry from the hull of the grain.", "[0027] The next step in the method is shown at block 18 which is an optional step of scouring the grain to remove fatty oils or lipids.", "There are two distinct advantages for de-fatting the Milo grain at this stage.", "The first is enhancing the consistency and repeatability of the extrusion process because fats in the grain tend to act as a lubricant through the extrusion die, thereby degrading extruder operation.", "The second advantage is the production of a more nutritional pet food which has less fat content.", "Well-known grain scouring processes may be used to remove the fatty endogerm from the Milo grain.", "Although scouring is discussed as a step in the basic method, it shall be understood that scouring is not necessarily required as it may be desirable in some circumstances to have certain levels of fat within the food product.", "Additionally, scouring may be eliminated to simplify the overall food production process.", "[0028] The next step in the method is shown at block 20 which involves introduction of a desired additive(s) to the processed Milo.", "The Milo and additive(s) may be referred to as a grain mix.", "For pet food, there are a number of additives which are contemplated within the present invention which may be advantageous for pet food or pet treats.", "Examples of these additives include additives in the form of food meals which may be derived from vegetable or animal protein sources.", "More specifically, one particular type of meal may include a liver meal which is known to be preferred by almost all dogs.", "To create a pet treat incorporating this liver meal having a light and puffy texture, the mixture ratio of the Milo to the liver meal would be from about 7:1 to about 12:1 by weight.", "Preferably, the ratio of the Milo to the liver meal is about 9:1 by weight.", "In order to provide an extrudable mixture, it is preferable to maintain the Milo at or around 16% moisture, and the liver meal at or around 20% moisture.", "Alternatively, to produce a pet treat which is not as puffy but rather is denser, smaller, and has more of a crunchy, nugget consistency, the ratio of Milo to liver meal would be from about 1:2 to about 5:2 by weight.", "Preferably, the the ratio of Milo to liver meal would be about 3:2 by weight.", "For this denser product, the moisture content prior to extrusion is preferably about 18-22%.", "Other additives which may be used include vitamins, minerals or other nutritional supplements.", "These additives can be added at this step in prescribed amounts which do not pose a health risk to the animals even in the event that a particular animal would consume a large number of the treats at a single time.", "Other types of additives which are also contemplated include medications, peanuts, fish meal, poultry meal, dried fruits or vegetables, flavored oils or other concentrated liquid flavorants.", "Milo is a grain which readily accepts a variety of additives, and there is little if any segregation or separation between the Milo grain and the additives in the extruded food product.", "[0029] It may be desirable to mechanically mix the grain mix in a bin which will then meter the grain mix into the extrusion machine.", "Mechanical mixing helps to ensure uniform dispersion of the additive.", "It is also necessary to add water to the decorticated grain in order to create the grain mix with the necessary moisture content.", "It has been found in testing that Milo has approximately 10-12% moisture content prior to processing.", "In order to optimize extrusion, it has been found through testing that a moisture content of about 16% is preferable.", "[0030] The next step in the method is illustrated at block 22 which involves extrusion of the Milo grain mix.", "Through testing, it has been found that extrusion can be achieved utilizing a bake-type extruder which exposes the grain mix to heat in the range of about 325° F. to about 400° F., and pressure in the range of about 1500 psi to about 2,000 psi.", "The particular shape of the die used in the extruding machine may be adapted to produce a food product of a desired shape.", "One example of a die could include the use of a die having a round shaped hole with a diameter of approximately 0.120 inch.", "The cutting mechanism used in the extruding machine can be adapted for cutting the extrudate to a length of about three-quarters inch.", "For a grain mix which is extruded having an overall moisture content of approximately 16%, the resulting extruded product has a light, puffy and cellular consistency at moisture contents above about 18%.", "As moisture content is increased in the grain mix, the resulting food product is smaller and denser as the product will experience less expansion during extrusion.", "For example, a food product having a more nugget-like consistency can be produced which is still crunchy, but does not have the puffy, cellular consistency.", "Temperature and pressure can also be adjusted within the extrusion process to produce a food product which is of a desired size, shape and density.", "Generally, increasing temperature and pressure will increase the expansion of the grain mix during extrusion.", "[0031] The last step of the method is shown at block 24 which contemplates curing the food product to thereby stabilize the product prior to shipping.", "Depending upon the texture and consistency of the food product produced, i.e., one that is either puffed or more dense, a certain amount of curing may be required to allow the food product to reach equilibrium in terms of moisture content.", "[0032] There are a number of advantages of utilizing a Milo matrix as a food product.", "First, there is the relatively low cost of producing such a food product as the processing steps for creating the Milo matrix can be achieved within a relatively simple grain processing method.", "Milo grain is a relatively high protein, low fat grain which is both palatable and easily digestible by both humans and animals.", "Processed Milo is generally hydrophobic, therefore very stable in all climates and storing conditions.", "Accordingly, the food product produced may be packaged and sold within packaging which does not have to be sealed or otherwise specially treated.", "For example, large bins of the Milo food product can be directly incorporated within retail locations where a consumer measures a desired amount of the food product to be purchased and then places the product into a plastic or paper bag.", "A Milo food product made by the above-described method requires no chemical additives to preserve the product for extended shelf life.", "Another advantage as mentioned above is the ability to produce food products which have a variety of densities.", "Lighter, puffier products as well as denser, crunchier products may be easily produced.", "By varying the temperature and pressure of the extrusion, or adjusting the moisture content, the particular size and density of the product can be chosen.", "For example, extruding the Milo grain mix through a die having a round opening of about 0.120 of an inch in diameter and at about 16% moisture content, can produce a product having a width/diameter of approximately three-quarters inch, which then can also be cut to a desired length.", "Increasing the moisture to about 18% has been shown to produce a product having a width/diameter of approximately one-half inch.", "During the extrusion process, the heat and pressure advantageously kill bacteria and other undesirable microorganisms thereby increasing the shelf life of the product.", "Also during extrusion, the additives become evenly mixed within the decorticated grain thereby producing a homogeneous mixture.", "Accordingly, the additive is evenly distributed throughout each batch of the extruded pet food product in contrast to many other types of pet treats, into which flavorings or additives are incorporated by an electrostatic process which simply coats the exterior surface of the product.", "These methods of incorporating a flavoring/additive are less desirable because the flavoring/additive is more easily separated from the product.", "By creating a homogeneous mixture through the extrusion process of the present invention, the desired additive is better delivered to the consuming animal.", "[0033] In accordance with another preferred embodiment of the present invention, other types of grains may be used to produce the food product.", "For example, corn, wheat and rice can also be used as the basic grains which are processed in the present invention.", "With these grains;", "however, an additional processing step is required to remove the starch from the remaining part of the grain.", "The removed starch is typically in powder form.", "In their natural state, these other grains are very difficult to extrude successfully, and therefore, the part of the grain to be extruded, the amylose starch, is separated from the whole grain prior to extrusion.", "Milo also contains starch, best characterized as an amylose -pectin starch.", "However, after decortication, Milo is readily extrudable without also having to first isolate the starch component of the grain.", "[0034] In addition to grains in which starch has been removed for use in extrusion, it is also contemplated within the present invention to use the starch extracted from tubers, such as potatoes.", "As with the Milo grain, these extracted starches must also receive the required amount of water to raise the moisture content to a desired level corresponding to the texture and density of the final product.", "[0035] Referring again to FIG. 1, the additional step of separating the starch is shown at block 30 in dotted lines.", "Additives are added to the starch in step 20 , and then the mixture is extruded at step 22 .", "The final step again would be curing, as required, at step 24 .", "In accordance with another aspect of the invention, the grain mix can also be mixed with a gelatin prior to extrusion thereby increasing the hardness of the resulting extruded food product.", "[0036] The above invention has been described with respect to preferred embodiments;", "however, other changes and modifications may be made within the spirit and scope of the invention." ]
CROSS REFERENCE TO RELATED APPLICATIONS The present application claims priority from provisional application Ser. No. 60/871,495, filed Dec. 22, 2006. FIELD OF THE INVENTION This invention pertains generally to a system and method for the evaluation of an electrocardiogram. BACKGROUND OF THE INVENTION An electrocardiogram (ECG) of a single heartbeat is commonly referred to as a PQRST complex. The PQRST wave includes a P-wave that corresponds to activity in the atria, a QRS complex that represents the electrical activation of the ventricles, and a T-wave that represents the electrical recovery or recharge phase of the ventricles. The QT interval is the time between the QRS onset and the end of the T-wave, and is commonly measured for purposes of evaluating cardiac electrical stability and thereby predicting potentially life threatening medical conditions such as cardiac arrhythmia. Some pharmaceuticals have side affects that increase the QT interval of an otherwise healthy patient and induce unstable cardiac electrical activity. Therefore, the FDA has begun to perform a drug-induced QT study on new pharmaceuticals prior to their approval. One problem is that an increase in QT interval is not directly correlated with cardiac electrical instability and another problem is that the QT interval is difficult to precisely measure. Therefore, if we only rely on the QT interval, there is the potential for the exclusion of beneficial pharmaceuticals based on the erroneous assumption that they may cause electrical instability and malignant cardiac arrhythmias. Studies have shown that an increase of heterogeneity in the re-polarization of the heart is directly linked to cardiac electrical instability. Accordingly, an attempt has been made to find the ECG features which have a higher correlation with the heterogeneity of the re-polarization as an indicator of cardiac electrical instability. More recently, it has been determined that the shape of the T-wave is an ECG feature that can be evaluated to more accurately asses cardiac electrical stability. As an example, T-wave flatness, asymmetry, and the presence of a “notch” in the T-wave have been correlated with unstable cardiac electrical activity. The problem is that, although T-wave shape observation has the potential to more accurately assess cardiac electrical stability, its consistency relies on the quality of data defining the T-wave. For example, a twelve lead ECG provides 12 separate T-waves representing different electrical views/projections of cardiac re-polarization. Therefore, if the optimal and most consistent T-wave representation is not implemented for observation, it will be difficult to assess a re-polarization abnormality based on any particular lead. Another problem relates to the placement of the sensors or transducers on a patient for the purpose of monitoring the electrical activity of the patient's heart. The conventional process involves placing multiple sensors at a variety of locations selected to optimally monitor the electrical activity. As the optimal sensor placement location varies during the course of the electrical cycle, and varies from patient to patient, it is currently not feasible to ensure that a sensor is placed at every optimal location for every patient. SUMMARY OF THE INVENTION The above-mentioned shortcomings, disadvantages and problems are addressed herein which will be understood by reading and understanding the following specification. In an embodiment, a method for evaluating an electrocardiogram includes measuring an electrical activity of a patient, processing the measured electrical activity to form a multi-lead signal, and extracting a segment of the multi-lead signal. The method for evaluating an electrocardiogram also includes transforming the segment of the multi-lead signal into a synthesized signal that is most representative of the patient's electrical activity, and evaluating the synthesized signal. In another embodiment, a method for evaluating an electrocardiogram includes measuring an electrical activity of a patient, processing the measured electrical activity to form a multi-lead signal, converting the multi-lead signal into a multi-dimensional representation, and extracting a segment from the multi-dimensional representation. The method for evaluating an electrocardiogram also includes performing a principal component analysis on the multi-dimensional representation to provide a synthesized signal that is most representative of the patient's electrical activity, and evaluating the synthesized signal. In yet another embodiment, a system for evaluating an electrocardiogram includes a plurality of leads attachable to a patient. The plurality of leads are configured to measure an electrical activity of the patient. The system for evaluating an electrocardiogram also includes a diagnostic system operatively connected to the plurality of leads. The diagnostic system is configured to form a multi-lead signal based on the measured electrical activity, extract a segment of the multi-lead signal, and transform the segment of the multi-lead signal into a synthesized signal that most accurately reflects the patient's electrical activity. Various other features, objects, and advantages of the invention will be made apparent to those skilled in the art from the accompanying drawings and detailed description thereof. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of a cardiac diagnostic/monitoring system operatively connected to a patient via a twelve lead system in accordance with an embodiment; FIG. 2 is an electrocardiogram; and FIG. 3 is a block diagram illustrating a method in accordance with an embodiment. DETAILED DESCRIPTION OF THE INVENTION In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments that may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, and it is to be understood that other embodiments may be utilized and that logical, mechanical, electrical and other changes may be made without departing from the scope of the embodiments. The following detailed description is, therefore, not to be taken as limiting the scope of the invention. Referring to FIG. 1 , a schematically represented cardiac diagnostic/monitoring system 10 is adapted measure an electrical signal generated by a patient's heart. The cardiac diagnostic/monitoring system 10 can be coupled to the patient 12 by an array of sensors or transducers. In the illustrated embodiment, the array of sensors include a right arm electrode RA; a left arm electrode LA; chest electrodes V 1 , V 2 , V 3 , V 4 , V 5 and V 6 ; a right leg electrode RL; and a left electrode leg LL for acquiring a standard twelve lead, ten-electrode electrocardiogram (ECG) signal. The twelve ECG leads include leads I, II, V 1 , V 2 , V 3 , V 4 , V 5 and V 6 which are acquired directly from the patient leads, and leads III, aVR, aVL and aVF which are derived using Einthoven's law. In other embodiments, alternative configurations of sensors and sensor locations can be used to acquire a standard or non-standard ECG signal. For example, an expanded fifteen lead system, including four extra electrodes, can be used to form Frank X, Y and Z leads. Referring to FIG. 2 , an electrocardiogram of a single heartbeat typically referred to as a PQRST complex is shown. The portion of the PQRST complex defined between reference points 14 and 16 is defined as the P-wave, and corresponds to activity in the atria. The portion of the PQRST complex defined between reference points 16 and 18 is defined as the QRS complex, and represents the electrical activation of the ventricles. The portion of the PQRST complex defined between reference points 18 and 20 is defined as the T-wave, and represents the electrical recovery or recharge phase of the ventricles. As is known in the art, the distinct portions or segments of the PQRST complex can be broken up and individually evaluated through a process known as segment extraction. It has been observed that an evaluation of the shape of an extracted T-wave can be used to evaluate the electrical stability of a patient's heart. For example, it is known that overly flat T-waves, certain shapes of asymmetric T-waves, and T-waves that include one or more “notches” are linked to unstable cardiac electrical activity that can lead, for example, to cardiac arrhythmia. T-wave shape evaluation may be performed manually or may be automated such as with a computer algorithm configured to identify T-wave data falling outside a predefined range. The twelve ECG leads (e.g., leads I, II, III, V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , aVR, aVL and aVF) obtained by the cardiac diagnostic/monitoring system 10 (shown in FIG. 1 ) produce twelve different electrocardiograms that represent the electrical activity of a patient's heart with varying degrees of precision. The degree of precision with which a particular lead represents the heart's electrical activity is based in part on the placement of the corresponding electrode or electrodes. The electrodes V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , RA, LA, RL, LL that are in closest proximity to and/or are most optimally aligned with the electrical activity of the heart at any given time receive the strongest signal and are therefore best adapted to monitor such electrical activity. Accordingly, the ECG lead based on an electrode or electrodes that are in closest proximity to and/or are most optimally aligned with the electrical activity of the heart generally provide the most accurate reflection of this electrical activity. The optimal location on a given patient for electrode placement varies during the course of the heart's electrical cycle, and varies from patient to patient. Therefore, it is often the case that variation of the placement of the electrodes V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , RA, LA, RL, LL can affect the diagnostic accuracy. As will be described in detail hereinafter, an embodiment of this invention estimates the data that would be provided from a robust representative lead even if none of the electrodes are accurately placed on the patient 12 . Advantageously, this provides the most accurate and reflective data for purposes of generating and evaluating an electrocardiogram. Having described the cardiac diagnostic/monitoring system 10 in accordance with an embodiment, a method for electrocardiogram evaluation will now be described. The method will hereinafter be described as being applied to the T-wave segment of an electrocardiogram for purposes of evaluating T-wave shape. It should, however, be appreciated that alternative methods may be applied to an entire electrocardiogram, or to any other electrocardiogram segment. Referring to FIG. 3 , a block diagram illustrates a method 100 . The individual blocks 102 - 112 represent steps that may be performed in accordance with the method 100 . Unless otherwise specified, the steps 102 - 112 need not be performed in the order shown. At step 102 , a patient's electrical activity is measured such as, for example, with the cardiac diagnostic/monitoring system 10 (shown in FIG. 1 ). According to one example, the electrical activity measured at step 102 is produced by the patient's heart. The patient may be a human or an animal. At step 104 , the electrical activity measured at step 102 is processed to form a multi-lead ECG signal such as, for example, with the cardiac diagnostic/monitoring system 10 . According to the exemplary embodiment illustrated in FIG. 1 , the multi-lead ECG signal is a twelve lead ECG signal including the leads I, II, III, V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , aVR, aVL and aVF. Step 106 is an optional step wherein the multi-lead ECG signal of step 104 is converted to a multi-dimensional ECG representation. According to one embodiment, the multi-lead ECG signal is a twelve lead ECG signal, and the multi-dimensional ECG representation is a three-dimensional ECG representation having orthogonal X, Y and Z leads. Step 106 can be skipped if the cardiac diagnostic/monitoring system 10 (shown in FIG. 1 ) is replaced with a system adapted to provide orthogonal X, Y and Z lead data such as, for example, the Frank lead system. The following equations may be implemented to convert twelve lead data (eight independent leads) into orthogonal X, Y and Z lead data: X=− 0.1106* v 1+0.045* v 2−0.04* v 3+0.2146* v 4−0.067* v 5+0.6868* v 6+0.3872* I− 0.1993* II Y= 0.1855* v 1−0.0728* v 2+0.0186* v 3+0.0154* v 4−0.1148* v 5+0.0682* v 6−0.0695* I+ 1.145* II Z= 0.3665* v 1−0.0363* v 2+0.165* v 3+0.2041* v 4+0.1395* v 5−0.4688* v 6+0.0587* I+ 0.0815* II This conversion matrix was developed from 5,000 fifteen lead ECG systems (i.e., standard twelve lead plus Frank X, Y and Z lead systems), and a regression analysis run between 5,000 paired twelve lead and Frank X, Y and Z lead systems. Any other known methods for converting from a multi-lead ECG signal to a multi-dimensional ECG representation, such as the inverse Dower method, may alternatively be implemented at step 106 . According to the exemplary embodiment wherein the multi-dimensional ECG representation is a three-dimensional representation, the orthogonal X, Y and Z lead data models the heart as a three-dimensional dipole source producing an electrical signal that varies based on the distance from the heart in the X, Y and Z directions. This is known as a dipole vector model, and the X, Y and Z lead data respectively defines the X, Y and Z components of the dipole source. Step 108 is an optional step in which one or more segments of the PQRST complex (shown in FIG. 2 ) are extracted. According to one embodiment, the T-wave segment of the PQRST complex is extracted at step 108 . According to another embodiment, both the T-wave and the QRS complex segments of the PQRST complex are extracted. At step 110 , the multi-dimensional ECG signals of step 106 are transformed into at least one synthesized ECG signal representing an optimally oriented projection vector. The synthesized ECG signal defines the highest energy vector at any given time. The “highest energy vector” conveys both magnitude and direction of the cardiac electrical activity as measured by an optimally placed electrode. Even if none of the electrodes V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , RA, LA, RL, LL (shown in FIG. 1 ) are actually placed in the optimal location, the synthesized ECG signal still provides an estimate of the data that would represent the major heart re-polarization activity. The synthesized ECG signal of step 110 yields a more robust representation of heart's actual electrical activity than would otherwise be obtainable by selecting a single physically obtained or derived lead. According to one embodiment, the transform of step 110 is obtained by performing principal component analysis (PCA) on the multi-dimensional ECG signals of step 106 . Principal component analysis is known to those skilled in the art and therefore will not be described in detail. According to alternate embodiments, the transform of step 110 may be performed by other processes such as independent component analysis (ICA), nonlinear component analysis (NLCA), factor analysis (FA), projection pursuit (PP), singular value decomposition (SVD), and similar techniques. At step 112 , the output of the transform performed at step 110 is analyzed. It should be appreciated that many different types of analyses can benefit from the method 100 as the data on which the analysis is based is most reflective of the patient's actual electrical cardiac activity. In a non-limiting manner, the following will describe several exemplary analyses that may be performed at step 112 . According to an embodiment wherein the T-wave segment of the PQRST complex is extracted at step 108 , the analysis of step 112 may include evaluating the shape of the T-wave defined by a principal PCA vector. The T-wave shape evaluation may look for features such as flatness, asymmetry, and the presence of a notch which are linked to unstable cardiac electrical activity. According to an embodiment wherein the T-wave segment of the PQRST complex is extracted at step 108 , the analysis of step 112 may include evaluating the shape of the T-wave defined by a second PCA vector. The T-wave shape evaluation may look for features such as flatness, asymmetry, and the presence of a notch which are linked to unstable cardiac electrical activity. According to an embodiment wherein the T-wave segment of the PQRST complex is extracted at step 108 , the analysis of step 112 may include evaluating the orientation of the principal PCA vector relative to the second PCA vector. According to an embodiment wherein the T-wave segment of the PQRST complex is extracted at step 108 , the analysis of step 112 may include evaluating the orientation of the projection vector represented by the synthesized ECG signal relative to the X, Y and Z lead vectors. These angles can be calculated using basic geometry principles as will be appreciated by those skilled in the art. The orientation of the projection vector represented by the synthesized ECG signal relative to the X, Y and Z lead vectors is one of the features that is indicative of cardiac electrical stability such that the method 100 can be used to predict heart problems including arrhythmia. According to an embodiment wherein both the T-wave and the QRS complex segments of the PQRST complex are extracted at step 108 , the analysis of step 112 may include evaluating the orientation of the projection vector representing the T-wave relative to the projection vector representing the QRS complex. The orientation of the projection vector representing the T-wave relative to the projection vector representing the QRS complex is indicative of cardiac electrical stability such that the method 100 can be used to predict heart problems including arrhythmia. According to an embodiment wherein both the T-wave and the QRS complex segments of the PQRST complex are extracted at step 108 , the analysis of step 112 may include evaluating the length of the QT interval as represented by the synthesized ECG signal. The length of the QT interval is indicative of cardiac electrical stability and therefore can be used to predict heart problems including arrhythmia. While the invention has been described with reference to preferred embodiments, those skilled in the art will appreciate that certain substitutions, alterations and omissions may be made to the embodiments without departing from the spirit of the invention. Accordingly, the foregoing description is meant to be exemplary only, and should not limit the scope of the invention as set forth in the following claims.
A method for evaluating an electrocardiogram is disclosed herein. The method includes measuring an electrical activity of a patient, processing the measured electrical activity to form a multi-lead signal, and extracting a segment of the multi-lead signal. The method for evaluating an electrocardiogram also includes transforming the segment of the multi-lead signal into a synthesized signal that is most representative of the patient's electrical activity, and evaluating the synthesized signal. A corresponding system for evaluating an electrocardiogram is also disclosed.
Summarize the information, clearly outlining the challenges and proposed solutions.
[ "CROSS REFERENCE TO RELATED APPLICATIONS The present application claims priority from provisional application Ser.", "No. 60/871,495, filed Dec. 22, 2006.", "FIELD OF THE INVENTION This invention pertains generally to a system and method for the evaluation of an electrocardiogram.", "BACKGROUND OF THE INVENTION An electrocardiogram (ECG) of a single heartbeat is commonly referred to as a PQRST complex.", "The PQRST wave includes a P-wave that corresponds to activity in the atria, a QRS complex that represents the electrical activation of the ventricles, and a T-wave that represents the electrical recovery or recharge phase of the ventricles.", "The QT interval is the time between the QRS onset and the end of the T-wave, and is commonly measured for purposes of evaluating cardiac electrical stability and thereby predicting potentially life threatening medical conditions such as cardiac arrhythmia.", "Some pharmaceuticals have side affects that increase the QT interval of an otherwise healthy patient and induce unstable cardiac electrical activity.", "Therefore, the FDA has begun to perform a drug-induced QT study on new pharmaceuticals prior to their approval.", "One problem is that an increase in QT interval is not directly correlated with cardiac electrical instability and another problem is that the QT interval is difficult to precisely measure.", "Therefore, if we only rely on the QT interval, there is the potential for the exclusion of beneficial pharmaceuticals based on the erroneous assumption that they may cause electrical instability and malignant cardiac arrhythmias.", "Studies have shown that an increase of heterogeneity in the re-polarization of the heart is directly linked to cardiac electrical instability.", "Accordingly, an attempt has been made to find the ECG features which have a higher correlation with the heterogeneity of the re-polarization as an indicator of cardiac electrical instability.", "More recently, it has been determined that the shape of the T-wave is an ECG feature that can be evaluated to more accurately asses cardiac electrical stability.", "As an example, T-wave flatness, asymmetry, and the presence of a “notch”", "in the T-wave have been correlated with unstable cardiac electrical activity.", "The problem is that, although T-wave shape observation has the potential to more accurately assess cardiac electrical stability, its consistency relies on the quality of data defining the T-wave.", "For example, a twelve lead ECG provides 12 separate T-waves representing different electrical views/projections of cardiac re-polarization.", "Therefore, if the optimal and most consistent T-wave representation is not implemented for observation, it will be difficult to assess a re-polarization abnormality based on any particular lead.", "Another problem relates to the placement of the sensors or transducers on a patient for the purpose of monitoring the electrical activity of the patient's heart.", "The conventional process involves placing multiple sensors at a variety of locations selected to optimally monitor the electrical activity.", "As the optimal sensor placement location varies during the course of the electrical cycle, and varies from patient to patient, it is currently not feasible to ensure that a sensor is placed at every optimal location for every patient.", "SUMMARY OF THE INVENTION The above-mentioned shortcomings, disadvantages and problems are addressed herein which will be understood by reading and understanding the following specification.", "In an embodiment, a method for evaluating an electrocardiogram includes measuring an electrical activity of a patient, processing the measured electrical activity to form a multi-lead signal, and extracting a segment of the multi-lead signal.", "The method for evaluating an electrocardiogram also includes transforming the segment of the multi-lead signal into a synthesized signal that is most representative of the patient's electrical activity, and evaluating the synthesized signal.", "In another embodiment, a method for evaluating an electrocardiogram includes measuring an electrical activity of a patient, processing the measured electrical activity to form a multi-lead signal, converting the multi-lead signal into a multi-dimensional representation, and extracting a segment from the multi-dimensional representation.", "The method for evaluating an electrocardiogram also includes performing a principal component analysis on the multi-dimensional representation to provide a synthesized signal that is most representative of the patient's electrical activity, and evaluating the synthesized signal.", "In yet another embodiment, a system for evaluating an electrocardiogram includes a plurality of leads attachable to a patient.", "The plurality of leads are configured to measure an electrical activity of the patient.", "The system for evaluating an electrocardiogram also includes a diagnostic system operatively connected to the plurality of leads.", "The diagnostic system is configured to form a multi-lead signal based on the measured electrical activity, extract a segment of the multi-lead signal, and transform the segment of the multi-lead signal into a synthesized signal that most accurately reflects the patient's electrical activity.", "Various other features, objects, and advantages of the invention will be made apparent to those skilled in the art from the accompanying drawings and detailed description thereof.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of a cardiac diagnostic/monitoring system operatively connected to a patient via a twelve lead system in accordance with an embodiment;", "FIG. 2 is an electrocardiogram;", "and FIG. 3 is a block diagram illustrating a method in accordance with an embodiment.", "DETAILED DESCRIPTION OF THE INVENTION In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments that may be practiced.", "These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, and it is to be understood that other embodiments may be utilized and that logical, mechanical, electrical and other changes may be made without departing from the scope of the embodiments.", "The following detailed description is, therefore, not to be taken as limiting the scope of the invention.", "Referring to FIG. 1 , a schematically represented cardiac diagnostic/monitoring system 10 is adapted measure an electrical signal generated by a patient's heart.", "The cardiac diagnostic/monitoring system 10 can be coupled to the patient 12 by an array of sensors or transducers.", "In the illustrated embodiment, the array of sensors include a right arm electrode RA;", "a left arm electrode LA;", "chest electrodes V 1 , V 2 , V 3 , V 4 , V 5 and V 6 ;", "a right leg electrode RL;", "and a left electrode leg LL for acquiring a standard twelve lead, ten-electrode electrocardiogram (ECG) signal.", "The twelve ECG leads include leads I, II, V 1 , V 2 , V 3 , V 4 , V 5 and V 6 which are acquired directly from the patient leads, and leads III, aVR, aVL and aVF which are derived using Einthoven's law.", "In other embodiments, alternative configurations of sensors and sensor locations can be used to acquire a standard or non-standard ECG signal.", "For example, an expanded fifteen lead system, including four extra electrodes, can be used to form Frank X, Y and Z leads.", "Referring to FIG. 2 , an electrocardiogram of a single heartbeat typically referred to as a PQRST complex is shown.", "The portion of the PQRST complex defined between reference points 14 and 16 is defined as the P-wave, and corresponds to activity in the atria.", "The portion of the PQRST complex defined between reference points 16 and 18 is defined as the QRS complex, and represents the electrical activation of the ventricles.", "The portion of the PQRST complex defined between reference points 18 and 20 is defined as the T-wave, and represents the electrical recovery or recharge phase of the ventricles.", "As is known in the art, the distinct portions or segments of the PQRST complex can be broken up and individually evaluated through a process known as segment extraction.", "It has been observed that an evaluation of the shape of an extracted T-wave can be used to evaluate the electrical stability of a patient's heart.", "For example, it is known that overly flat T-waves, certain shapes of asymmetric T-waves, and T-waves that include one or more “notches”", "are linked to unstable cardiac electrical activity that can lead, for example, to cardiac arrhythmia.", "T-wave shape evaluation may be performed manually or may be automated such as with a computer algorithm configured to identify T-wave data falling outside a predefined range.", "The twelve ECG leads (e.g., leads I, II, III, V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , aVR, aVL and aVF) obtained by the cardiac diagnostic/monitoring system 10 (shown in FIG. 1 ) produce twelve different electrocardiograms that represent the electrical activity of a patient's heart with varying degrees of precision.", "The degree of precision with which a particular lead represents the heart's electrical activity is based in part on the placement of the corresponding electrode or electrodes.", "The electrodes V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , RA, LA, RL, LL that are in closest proximity to and/or are most optimally aligned with the electrical activity of the heart at any given time receive the strongest signal and are therefore best adapted to monitor such electrical activity.", "Accordingly, the ECG lead based on an electrode or electrodes that are in closest proximity to and/or are most optimally aligned with the electrical activity of the heart generally provide the most accurate reflection of this electrical activity.", "The optimal location on a given patient for electrode placement varies during the course of the heart's electrical cycle, and varies from patient to patient.", "Therefore, it is often the case that variation of the placement of the electrodes V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , RA, LA, RL, LL can affect the diagnostic accuracy.", "As will be described in detail hereinafter, an embodiment of this invention estimates the data that would be provided from a robust representative lead even if none of the electrodes are accurately placed on the patient 12 .", "Advantageously, this provides the most accurate and reflective data for purposes of generating and evaluating an electrocardiogram.", "Having described the cardiac diagnostic/monitoring system 10 in accordance with an embodiment, a method for electrocardiogram evaluation will now be described.", "The method will hereinafter be described as being applied to the T-wave segment of an electrocardiogram for purposes of evaluating T-wave shape.", "It should, however, be appreciated that alternative methods may be applied to an entire electrocardiogram, or to any other electrocardiogram segment.", "Referring to FIG. 3 , a block diagram illustrates a method 100 .", "The individual blocks 102 - 112 represent steps that may be performed in accordance with the method 100 .", "Unless otherwise specified, the steps 102 - 112 need not be performed in the order shown.", "At step 102 , a patient's electrical activity is measured such as, for example, with the cardiac diagnostic/monitoring system 10 (shown in FIG. 1 ).", "According to one example, the electrical activity measured at step 102 is produced by the patient's heart.", "The patient may be a human or an animal.", "At step 104 , the electrical activity measured at step 102 is processed to form a multi-lead ECG signal such as, for example, with the cardiac diagnostic/monitoring system 10 .", "According to the exemplary embodiment illustrated in FIG. 1 , the multi-lead ECG signal is a twelve lead ECG signal including the leads I, II, III, V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , aVR, aVL and aVF.", "Step 106 is an optional step wherein the multi-lead ECG signal of step 104 is converted to a multi-dimensional ECG representation.", "According to one embodiment, the multi-lead ECG signal is a twelve lead ECG signal, and the multi-dimensional ECG representation is a three-dimensional ECG representation having orthogonal X, Y and Z leads.", "Step 106 can be skipped if the cardiac diagnostic/monitoring system 10 (shown in FIG. 1 ) is replaced with a system adapted to provide orthogonal X, Y and Z lead data such as, for example, the Frank lead system.", "The following equations may be implemented to convert twelve lead data (eight independent leads) into orthogonal X, Y and Z lead data: X=− 0.1106* v 1+0.045* v 2−0.04* v 3+0.2146* v 4−0.067* v 5+0.6868* v 6+0.3872* I− 0.1993* II Y= 0.1855* v 1−0.0728* v 2+0.0186* v 3+0.0154* v 4−0.1148* v 5+0.0682* v 6−0.0695* I+ 1.145* II Z= 0.3665* v 1−0.0363* v 2+0.165* v 3+0.2041* v 4+0.1395* v 5−0.4688* v 6+0.0587* I+ 0.0815* II This conversion matrix was developed from 5,000 fifteen lead ECG systems (i.e., standard twelve lead plus Frank X, Y and Z lead systems), and a regression analysis run between 5,000 paired twelve lead and Frank X, Y and Z lead systems.", "Any other known methods for converting from a multi-lead ECG signal to a multi-dimensional ECG representation, such as the inverse Dower method, may alternatively be implemented at step 106 .", "According to the exemplary embodiment wherein the multi-dimensional ECG representation is a three-dimensional representation, the orthogonal X, Y and Z lead data models the heart as a three-dimensional dipole source producing an electrical signal that varies based on the distance from the heart in the X, Y and Z directions.", "This is known as a dipole vector model, and the X, Y and Z lead data respectively defines the X, Y and Z components of the dipole source.", "Step 108 is an optional step in which one or more segments of the PQRST complex (shown in FIG. 2 ) are extracted.", "According to one embodiment, the T-wave segment of the PQRST complex is extracted at step 108 .", "According to another embodiment, both the T-wave and the QRS complex segments of the PQRST complex are extracted.", "At step 110 , the multi-dimensional ECG signals of step 106 are transformed into at least one synthesized ECG signal representing an optimally oriented projection vector.", "The synthesized ECG signal defines the highest energy vector at any given time.", "The “highest energy vector”", "conveys both magnitude and direction of the cardiac electrical activity as measured by an optimally placed electrode.", "Even if none of the electrodes V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , RA, LA, RL, LL (shown in FIG. 1 ) are actually placed in the optimal location, the synthesized ECG signal still provides an estimate of the data that would represent the major heart re-polarization activity.", "The synthesized ECG signal of step 110 yields a more robust representation of heart's actual electrical activity than would otherwise be obtainable by selecting a single physically obtained or derived lead.", "According to one embodiment, the transform of step 110 is obtained by performing principal component analysis (PCA) on the multi-dimensional ECG signals of step 106 .", "Principal component analysis is known to those skilled in the art and therefore will not be described in detail.", "According to alternate embodiments, the transform of step 110 may be performed by other processes such as independent component analysis (ICA), nonlinear component analysis (NLCA), factor analysis (FA), projection pursuit (PP), singular value decomposition (SVD), and similar techniques.", "At step 112 , the output of the transform performed at step 110 is analyzed.", "It should be appreciated that many different types of analyses can benefit from the method 100 as the data on which the analysis is based is most reflective of the patient's actual electrical cardiac activity.", "In a non-limiting manner, the following will describe several exemplary analyses that may be performed at step 112 .", "According to an embodiment wherein the T-wave segment of the PQRST complex is extracted at step 108 , the analysis of step 112 may include evaluating the shape of the T-wave defined by a principal PCA vector.", "The T-wave shape evaluation may look for features such as flatness, asymmetry, and the presence of a notch which are linked to unstable cardiac electrical activity.", "According to an embodiment wherein the T-wave segment of the PQRST complex is extracted at step 108 , the analysis of step 112 may include evaluating the shape of the T-wave defined by a second PCA vector.", "The T-wave shape evaluation may look for features such as flatness, asymmetry, and the presence of a notch which are linked to unstable cardiac electrical activity.", "According to an embodiment wherein the T-wave segment of the PQRST complex is extracted at step 108 , the analysis of step 112 may include evaluating the orientation of the principal PCA vector relative to the second PCA vector.", "According to an embodiment wherein the T-wave segment of the PQRST complex is extracted at step 108 , the analysis of step 112 may include evaluating the orientation of the projection vector represented by the synthesized ECG signal relative to the X, Y and Z lead vectors.", "These angles can be calculated using basic geometry principles as will be appreciated by those skilled in the art.", "The orientation of the projection vector represented by the synthesized ECG signal relative to the X, Y and Z lead vectors is one of the features that is indicative of cardiac electrical stability such that the method 100 can be used to predict heart problems including arrhythmia.", "According to an embodiment wherein both the T-wave and the QRS complex segments of the PQRST complex are extracted at step 108 , the analysis of step 112 may include evaluating the orientation of the projection vector representing the T-wave relative to the projection vector representing the QRS complex.", "The orientation of the projection vector representing the T-wave relative to the projection vector representing the QRS complex is indicative of cardiac electrical stability such that the method 100 can be used to predict heart problems including arrhythmia.", "According to an embodiment wherein both the T-wave and the QRS complex segments of the PQRST complex are extracted at step 108 , the analysis of step 112 may include evaluating the length of the QT interval as represented by the synthesized ECG signal.", "The length of the QT interval is indicative of cardiac electrical stability and therefore can be used to predict heart problems including arrhythmia.", "While the invention has been described with reference to preferred embodiments, those skilled in the art will appreciate that certain substitutions, alterations and omissions may be made to the embodiments without departing from the spirit of the invention.", "Accordingly, the foregoing description is meant to be exemplary only, and should not limit the scope of the invention as set forth in the following claims." ]
BACKGROUND OF THE INVENTION The present invention relates to rail anchor removal. More particularly, it relates to removal of rail anchors using a track renewal machine. The rails of a railroad track are usually secured to cross ties by spikes driven into tie plates. These tie plates block lateral movement of the rails, i.e., movement that is transverse to the rail direction. Anchors are attached to the rails to secure the rails against longitudinal movement of the rails relative to the cross ties. When a rail is to be replaced or renovated, the spikes which secure the tie plates and rail to the ties are first removed. The rail anchors, which often are drive-on anchors, then are removed from the rails. Often the anchors are removed from the rails using manual labor. Specifically, a person swings a sledge hammer against the drive-on anchors, driving the anchors from the base of the rail. This is very physically demanding and labor intensive. Following the removal of the anchors, a track renewal machine with tie wagons in front of it travels along the section of rails where renewal is needed. The forgoing techniques have usually required removal of the anchors in advance of the tie wagons entering that section of the track. The track renewal machine then uses rail threaders which move the rails vertically up from the ties (more specifically from the tie plates on the ties) and spreads the rails out horizontally sufficiently far that old ties may be lifted up without hitting the rails. Various other operations are commonly performed such as inserting new ties, distributing ballast around the new ties, and applying rail clips. Either the old rails (if in acceptable condition) or new rails are then laid on the new cross ties and are secured in place. As used herein, a track renewal machine shall includes machines which spread out rails such that ties may be lifted up from in between the rails and any machines having rail threaders thereon. It will be understood, that if only the ties are to be replaced for a given section of track and the rails are not being replaced, a tie gang may be used. With a tie gang, the cross ties are removed from beneath the side of the rails, but without spreading the rails apart. This is a different process than the rail spreading track renewal discussed hereinabove. Devices have been developed to remove anchors automatically and without the manual labor associated with sledge hammer removal. However, such devices have increased the complexity of the already complex series of operations used in rail spreading track renewal. The following U.S. Patents and their issue dates are noted: U.S. Pat. No. 4,903,611 Holley Feb. 27, 1990 U.S. Pat. No. 5,146,677 Holman et al. Sep. 15, 1992 U.S. Pat. No. 5,269,225 Bosshart et al. Dec. 14, 1993 The Holley Patent shows an anchor spreader apparatus and method for using with tie gangs. The Holman Patent discloses a rail anchor remover mounted on a crane. The Bosshart Patent shows an apparatus and method for applying rail clips and insulators. None of these prior art devices have been found to be completely satisfactory. OBJECTS AND SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide a new and improved apparatus and method for removal of rail anchors. A more specific object of the present invention is to provide removal of anchors as part of the threading of the rails and with minimal need for additional machinery beyond the normal track renewal machinery. A further object of the present invention is to provide anchor removal with a simplified, automatic technique. Yet another object of the present invention is to provide anchor removal with automatic conveyance of removed anchors to an appropriate location so that they may be reused if suitable for reuse and may easily be disposed of if they are not suitable for reuse. The above and other features of the present invention are realized by a track renewal machine having a frame, right and left rail threaders that are supported by the frame so that the right and left rail threaders are positioned and operable to spread rails such that ties can be lifted therebetween. Right and left anchor removers are respectively mounted to the right and left rail threaders. The right and left anchor removers are supported by the main frame and are positioned adjacent the right and left rail threaders, respectively. A conveyor system is supported by the main frame and is position to receive anchors removed by the anchor removers and convey them to the side of the railroad track. More specifically, the conveyor system includes inclined right and left conveyor belts respectively positioned to receive anchors removed by the respective right and left anchor removers. The right and left conveyor belts extend lengthwise substantially parallel to the rail direction, i.e., the component of the belts' direction of movement in the horizontal plane is within 15 degrees of the rail direction. As used herein, the rail direction is the direction of the rails prior to their movement away from the ties under operation of the rail threaders. A transverse conveyer, i.e., transverse to the rail direction, such as a conveyor belt, is supported by the frame. The transverse conveyor receives anchors from upper ends of the right and left conveyor belts, carries the anchors to the side, and deposits them on the side of the railroad track. Each of the right and left anchor removers includes an anchor removing roller forward or upstream i.e., in the direction of movement, from the corresponding one of the rail threaders. Each of the rail threaders includes a threader base and a plurality of threader rollers rotatably mounted thereto. The threader rollers all contact the base of a rail passing through the threader and the threaders are operable to thread the rails without any rollers contacting the balls of the rails. Each of the anchor removing rollers is rotatably mounted to the corresponding threader base for rotation about an inclined transverse axis. Each of the rail threaders is mounted to a rail guidance frame supported by the main frame and extending transverse to the rail direction. An alternate embodiment includes an anchor collecting bin supported by the main frame and a conveyor system supported by the main frame and positioned to receive anchors removed by the anchor removers and convey them to the anchor collecting bin. The present invention may alternately be described as a method for track renewal including moving a track renewal machine along a section of railroad track, the track renewal machine having a front and lifting rails by having them thread through right and left rail threaders on the track renewal machine. Anchors are removed from the rails by use of right and left anchor removers on the track renewal machine. The right and left anchor removers are disposed upstream respectively of the right and left rail threaders such that anchors on the rails are removed between the front of the track renewal machine and the right and left rail threaders. The method also includes the steps of: supplying anchors as they are removed from the rails to a conveyor system; and conveying the caught anchors using the conveyor system to a side of a railroad track. The removal of the anchors by the right and left anchor removers is accomplished by anchor removing rollers supported by a base on the respective right and left rail threaders. The threading of the rails is performed by right and left rail threaders having a plurality of threader rollers rotatably mounted to the base of the corresponding right and left threaders. The threader rollers all contact the base of a rail passing through the threader and the threaders thread the rails without any rollers contacting the balls of the rails. The right and left rail threaders stabilize rail positions such that the anchor removing rollers of the right and left anchor removers can push the anchors for removal thereof without the anchor removing rollers moving the rails. BRIEF DESCRIPTION OF THE DRAWINGS The above and other features of the present invention will be more readily understood when the following detailed description is considered in conjunction with the accompanying drawings wherein like characters represent like parts throughout the several views and in which: FIG. 1 is a simplified side view of the anchor remover according to the present invention and with only some related portions of a track renewal machine shown; FIG. 2 is a front view of the anchor remover according to the present invention and with only portions of a track renewal machine shown; FIG. 3 is an enlarged top view of a conveyor arrangement and right and left anchor removers mounted to corresponding right and left rail threaders; FIG. 4 is a front view showing right and left side anchor removers and some related components; FIG. 5 is a side view of the overall track renewal machine according to the present invention; FIG. 6 is a front view of an alternate preferred embodiment having collecting bins. DETAILED DESCRIPTION With reference now to FIG. 1, a track renewal machine 10 according to the present invention is partially shown. The machine 10 has a frame 12. Since track renewal machines are generally well known, the present description will concentrate on differences between the present track renewal machine and previously known track renewal machines. Thus, little or no description of features common to prior track renewal machines will be presented herein. Initially, the relationship and operation of the primary components will be discussed. Various details of the construction of some of the primary components will then be discussed as appropriate. A rail guidance system 14 includes a rail guidance frame 16 (extending transverse to the lengthwise direction of the rails) and right and left rail threaders 18 (only one visible in FIG. 1). The present invention is essentially symmetric about a central axis extending in the rail direction (i.e., direction of the rails prior to their threading). Therefore, it will be readily understood that structures on the right and left sides are identical in construction and operation such that the description of one side will suffice to understand the other side. The rail guidance system 14 is a known structure and operates in known fashion with right and left rail threaders 18 lifting and separating the respective right and left rails. Unlike known rail guidance systems, rail guidance system 14 has right and left anchor removers 20 adjacent and mounted to the corresponding respective right and left rail threaders 18. The anchor removers 20 are supported by the frame 12 by way of rail guidance frame 16 since frame 16 is mounted to frame 12 in known fashion. As machine 10 travels leftwardly in the view of FIG. 1, the anchor removers 20 remove anchors just before the rails go through the corresponding one of rail threaders 18. The anchors which are removed (not separately shown in FIG. 1) are supplied to a conveyor system 22 for carrying such anchors to the side of the machine 10. Continuing to view FIG. 1, but also considering FIGS. 2-4, the various components will be discussed in more detail. A crawler mount 24 (FIGS. 2 and 4) is shown attached to a rail guidance system 14 for mounting a crawler (not shown) in known fashion. Each of the right and left rail threaders 18 includes a set of four upright threader rollers 28 (front field side, front gauge side, back field side, and back gauge side) which rotate about preferably vertical axes or at least substantially vertical axes, e.g., within 15 degrees of vertical. Each set of four upright rollers 28 cooperate with two horizontal rollers 30 which rotate about preferably horizontal axes or at least substantially horizontal axes, e.g., within 15 degrees of horizontal. The rollers 28 and 30, which are mounted on threader base plate 32, operate in known fashion to thread rails. The rails are threaded, as best shown in FIG. 2, by rollers 28 and 30 capturing the base or flange of the rails and without any of the rollers contacting the ball or upper part of the rails. Referring to FIG. 3, base 32 of each of the threaders 18 has mounted to it an anchor remover 20 including a support member 34 and cross support 36, both of which are welded or otherwise fixed to base 32. Anchor removal roller 38 is rotatably mounted to support member 34 for rotation about axis 40 (FIG. 2). Axis 40 extends transversely to the rail direction as shown in FIG. 3, and is inclined as shown in FIG. 2. The angle of inclination of axis 40 is preferably in a range between approximately 30 and 60 degrees relative to horizontal, more preferably in a range between approximately 40 and 50 degrees. Most preferably, the angle of inclination is about 45 degrees. As the anchors hit the anchor removal roller 38 (see FIGS. 2 and 3), the threader rollers 28 and 30 stabilize the rail relative to anchor removal roller 38 such that anchor removal roller 38 causes anchors to pop off of the rail just before the portion of the rail on which the anchor is disposed goes through rail guidance system 14. Referring now to FIGS. 1, 3 and 4, a funnel-like anchor catch or chute 42 is disposed adjacent to each of the right and left anchor removers 20. Each catch 42 deflects removed anchors onto the lower end of either right or left inclined conveyor belts 46. Conveyor belts 46 comprise an upper end disposed adjacent to a transverse conveyor belt 48. Each conveyor belt 46 carries the loose anchors to its upper end, where the anchors drop off onto transverse conveyor belt 48. Transverse (horizontal) conveyor belt 48 carries the loose anchors to either the right or left side of machine 10. As shown in FIG. 3, the upper ends of inclined conveyors 46 may be rotatably mounted by way of support 50 having right and left plates 52, transverse rod 54, and plates 56 mounted thereto. By having the upper ends of conveyors 46 rotatably supported by frame 12, conveyors 46 can be moved between the working position illustrated and a storage position (not shown) wherein the lower ends can be lifted up by either a hydraulic cylinder (not shown) or manually. In the storage position, the conveyors may be pinned or otherwise secured. With reference now of FIG. 5, the track renewal machine 10 with anchor removers 20 is shown together with other mechanisms used in track renewal including a gantry, handling car, beam car and trailer car. The more specific mechanisms shown also include a central crawler (which would attach to mount 24 of FIG. 2), old sleeper or cross tie pickup, ballast spreader, new sleeper or cross tie layer, rail heater, and clip applicator. None of the details of these specific mechanisms need be described herein, but it is noted that the rail heater and clip applicator are described in a co-pending application entitled RAIL HEATING AND CLIP APPLICATOR, invented by the inventor herein, assigned to the assignee of the present application, filed Apr. 14, 1997, Ser. No. 08/839,460, and hereby incorporated herein by reference. FIG. 6 shows an alternate embodiment machine 110 having components in the 100 series with the same last two digits as the corresponding component(s), if any, of the embodiment of FIGS. 1-4. Thus, components 112, 116, 120, 130, and 148 are identical in operation and construction as components 12, 16, 20, 30, and 48. Indeed, machine 110 functions and is constructed the same as machine 10 except as noted hereinbelow. Instead of transverse conveyor 148 depositing the loose anchors at the side of the road bed, support plates 160 have collecting bins 162 mounted thereto. Collecting bins 162 catch anchors that come off transverse conveyor 148 by way of one of the feeder guide plates 164. Although specific constructions have been presented herein, it is to be understood that these are for illustrative purposes only. Various modifications and adaptations will be apparent to those of skill in the art. In view of possible modifications, it will be appreciated that the scope of the present invention should be determined by reference to the claims appended hereto.
A track renewal machine and method provides removal of anchors after rails have been separated from the ties. The rails with anchors still on them are lifted from the ties and spread using a rail threader with the anchor remover attached to it.
Provide a concise summary of the essential information conveyed in the context.
[ "BACKGROUND OF THE INVENTION The present invention relates to rail anchor removal.", "More particularly, it relates to removal of rail anchors using a track renewal machine.", "The rails of a railroad track are usually secured to cross ties by spikes driven into tie plates.", "These tie plates block lateral movement of the rails, i.e., movement that is transverse to the rail direction.", "Anchors are attached to the rails to secure the rails against longitudinal movement of the rails relative to the cross ties.", "When a rail is to be replaced or renovated, the spikes which secure the tie plates and rail to the ties are first removed.", "The rail anchors, which often are drive-on anchors, then are removed from the rails.", "Often the anchors are removed from the rails using manual labor.", "Specifically, a person swings a sledge hammer against the drive-on anchors, driving the anchors from the base of the rail.", "This is very physically demanding and labor intensive.", "Following the removal of the anchors, a track renewal machine with tie wagons in front of it travels along the section of rails where renewal is needed.", "The forgoing techniques have usually required removal of the anchors in advance of the tie wagons entering that section of the track.", "The track renewal machine then uses rail threaders which move the rails vertically up from the ties (more specifically from the tie plates on the ties) and spreads the rails out horizontally sufficiently far that old ties may be lifted up without hitting the rails.", "Various other operations are commonly performed such as inserting new ties, distributing ballast around the new ties, and applying rail clips.", "Either the old rails (if in acceptable condition) or new rails are then laid on the new cross ties and are secured in place.", "As used herein, a track renewal machine shall includes machines which spread out rails such that ties may be lifted up from in between the rails and any machines having rail threaders thereon.", "It will be understood, that if only the ties are to be replaced for a given section of track and the rails are not being replaced, a tie gang may be used.", "With a tie gang, the cross ties are removed from beneath the side of the rails, but without spreading the rails apart.", "This is a different process than the rail spreading track renewal discussed hereinabove.", "Devices have been developed to remove anchors automatically and without the manual labor associated with sledge hammer removal.", "However, such devices have increased the complexity of the already complex series of operations used in rail spreading track renewal.", "The following U.S. Patents and their issue dates are noted: U.S. Pat. No. 4,903,611 Holley Feb. 27, 1990 U.S. Pat. No. 5,146,677 Holman et al.", "Sep. 15, 1992 U.S. Pat. No. 5,269,225 Bosshart et al.", "Dec. 14, 1993 The Holley Patent shows an anchor spreader apparatus and method for using with tie gangs.", "The Holman Patent discloses a rail anchor remover mounted on a crane.", "The Bosshart Patent shows an apparatus and method for applying rail clips and insulators.", "None of these prior art devices have been found to be completely satisfactory.", "OBJECTS AND SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide a new and improved apparatus and method for removal of rail anchors.", "A more specific object of the present invention is to provide removal of anchors as part of the threading of the rails and with minimal need for additional machinery beyond the normal track renewal machinery.", "A further object of the present invention is to provide anchor removal with a simplified, automatic technique.", "Yet another object of the present invention is to provide anchor removal with automatic conveyance of removed anchors to an appropriate location so that they may be reused if suitable for reuse and may easily be disposed of if they are not suitable for reuse.", "The above and other features of the present invention are realized by a track renewal machine having a frame, right and left rail threaders that are supported by the frame so that the right and left rail threaders are positioned and operable to spread rails such that ties can be lifted therebetween.", "Right and left anchor removers are respectively mounted to the right and left rail threaders.", "The right and left anchor removers are supported by the main frame and are positioned adjacent the right and left rail threaders, respectively.", "A conveyor system is supported by the main frame and is position to receive anchors removed by the anchor removers and convey them to the side of the railroad track.", "More specifically, the conveyor system includes inclined right and left conveyor belts respectively positioned to receive anchors removed by the respective right and left anchor removers.", "The right and left conveyor belts extend lengthwise substantially parallel to the rail direction, i.e., the component of the belts'", "direction of movement in the horizontal plane is within 15 degrees of the rail direction.", "As used herein, the rail direction is the direction of the rails prior to their movement away from the ties under operation of the rail threaders.", "A transverse conveyer, i.e., transverse to the rail direction, such as a conveyor belt, is supported by the frame.", "The transverse conveyor receives anchors from upper ends of the right and left conveyor belts, carries the anchors to the side, and deposits them on the side of the railroad track.", "Each of the right and left anchor removers includes an anchor removing roller forward or upstream i.e., in the direction of movement, from the corresponding one of the rail threaders.", "Each of the rail threaders includes a threader base and a plurality of threader rollers rotatably mounted thereto.", "The threader rollers all contact the base of a rail passing through the threader and the threaders are operable to thread the rails without any rollers contacting the balls of the rails.", "Each of the anchor removing rollers is rotatably mounted to the corresponding threader base for rotation about an inclined transverse axis.", "Each of the rail threaders is mounted to a rail guidance frame supported by the main frame and extending transverse to the rail direction.", "An alternate embodiment includes an anchor collecting bin supported by the main frame and a conveyor system supported by the main frame and positioned to receive anchors removed by the anchor removers and convey them to the anchor collecting bin.", "The present invention may alternately be described as a method for track renewal including moving a track renewal machine along a section of railroad track, the track renewal machine having a front and lifting rails by having them thread through right and left rail threaders on the track renewal machine.", "Anchors are removed from the rails by use of right and left anchor removers on the track renewal machine.", "The right and left anchor removers are disposed upstream respectively of the right and left rail threaders such that anchors on the rails are removed between the front of the track renewal machine and the right and left rail threaders.", "The method also includes the steps of: supplying anchors as they are removed from the rails to a conveyor system;", "and conveying the caught anchors using the conveyor system to a side of a railroad track.", "The removal of the anchors by the right and left anchor removers is accomplished by anchor removing rollers supported by a base on the respective right and left rail threaders.", "The threading of the rails is performed by right and left rail threaders having a plurality of threader rollers rotatably mounted to the base of the corresponding right and left threaders.", "The threader rollers all contact the base of a rail passing through the threader and the threaders thread the rails without any rollers contacting the balls of the rails.", "The right and left rail threaders stabilize rail positions such that the anchor removing rollers of the right and left anchor removers can push the anchors for removal thereof without the anchor removing rollers moving the rails.", "BRIEF DESCRIPTION OF THE DRAWINGS The above and other features of the present invention will be more readily understood when the following detailed description is considered in conjunction with the accompanying drawings wherein like characters represent like parts throughout the several views and in which: FIG. 1 is a simplified side view of the anchor remover according to the present invention and with only some related portions of a track renewal machine shown;", "FIG. 2 is a front view of the anchor remover according to the present invention and with only portions of a track renewal machine shown;", "FIG. 3 is an enlarged top view of a conveyor arrangement and right and left anchor removers mounted to corresponding right and left rail threaders;", "FIG. 4 is a front view showing right and left side anchor removers and some related components;", "FIG. 5 is a side view of the overall track renewal machine according to the present invention;", "FIG. 6 is a front view of an alternate preferred embodiment having collecting bins.", "DETAILED DESCRIPTION With reference now to FIG. 1, a track renewal machine 10 according to the present invention is partially shown.", "The machine 10 has a frame 12.", "Since track renewal machines are generally well known, the present description will concentrate on differences between the present track renewal machine and previously known track renewal machines.", "Thus, little or no description of features common to prior track renewal machines will be presented herein.", "Initially, the relationship and operation of the primary components will be discussed.", "Various details of the construction of some of the primary components will then be discussed as appropriate.", "A rail guidance system 14 includes a rail guidance frame 16 (extending transverse to the lengthwise direction of the rails) and right and left rail threaders 18 (only one visible in FIG. 1).", "The present invention is essentially symmetric about a central axis extending in the rail direction (i.e., direction of the rails prior to their threading).", "Therefore, it will be readily understood that structures on the right and left sides are identical in construction and operation such that the description of one side will suffice to understand the other side.", "The rail guidance system 14 is a known structure and operates in known fashion with right and left rail threaders 18 lifting and separating the respective right and left rails.", "Unlike known rail guidance systems, rail guidance system 14 has right and left anchor removers 20 adjacent and mounted to the corresponding respective right and left rail threaders 18.", "The anchor removers 20 are supported by the frame 12 by way of rail guidance frame 16 since frame 16 is mounted to frame 12 in known fashion.", "As machine 10 travels leftwardly in the view of FIG. 1, the anchor removers 20 remove anchors just before the rails go through the corresponding one of rail threaders 18.", "The anchors which are removed (not separately shown in FIG. 1) are supplied to a conveyor system 22 for carrying such anchors to the side of the machine 10.", "Continuing to view FIG. 1, but also considering FIGS. 2-4, the various components will be discussed in more detail.", "A crawler mount 24 (FIGS.", "2 and 4) is shown attached to a rail guidance system 14 for mounting a crawler (not shown) in known fashion.", "Each of the right and left rail threaders 18 includes a set of four upright threader rollers 28 (front field side, front gauge side, back field side, and back gauge side) which rotate about preferably vertical axes or at least substantially vertical axes, e.g., within 15 degrees of vertical.", "Each set of four upright rollers 28 cooperate with two horizontal rollers 30 which rotate about preferably horizontal axes or at least substantially horizontal axes, e.g., within 15 degrees of horizontal.", "The rollers 28 and 30, which are mounted on threader base plate 32, operate in known fashion to thread rails.", "The rails are threaded, as best shown in FIG. 2, by rollers 28 and 30 capturing the base or flange of the rails and without any of the rollers contacting the ball or upper part of the rails.", "Referring to FIG. 3, base 32 of each of the threaders 18 has mounted to it an anchor remover 20 including a support member 34 and cross support 36, both of which are welded or otherwise fixed to base 32.", "Anchor removal roller 38 is rotatably mounted to support member 34 for rotation about axis 40 (FIG.", "2).", "Axis 40 extends transversely to the rail direction as shown in FIG. 3, and is inclined as shown in FIG. 2. The angle of inclination of axis 40 is preferably in a range between approximately 30 and 60 degrees relative to horizontal, more preferably in a range between approximately 40 and 50 degrees.", "Most preferably, the angle of inclination is about 45 degrees.", "As the anchors hit the anchor removal roller 38 (see FIGS. 2 and 3), the threader rollers 28 and 30 stabilize the rail relative to anchor removal roller 38 such that anchor removal roller 38 causes anchors to pop off of the rail just before the portion of the rail on which the anchor is disposed goes through rail guidance system 14.", "Referring now to FIGS. 1, 3 and 4, a funnel-like anchor catch or chute 42 is disposed adjacent to each of the right and left anchor removers 20.", "Each catch 42 deflects removed anchors onto the lower end of either right or left inclined conveyor belts 46.", "Conveyor belts 46 comprise an upper end disposed adjacent to a transverse conveyor belt 48.", "Each conveyor belt 46 carries the loose anchors to its upper end, where the anchors drop off onto transverse conveyor belt 48.", "Transverse (horizontal) conveyor belt 48 carries the loose anchors to either the right or left side of machine 10.", "As shown in FIG. 3, the upper ends of inclined conveyors 46 may be rotatably mounted by way of support 50 having right and left plates 52, transverse rod 54, and plates 56 mounted thereto.", "By having the upper ends of conveyors 46 rotatably supported by frame 12, conveyors 46 can be moved between the working position illustrated and a storage position (not shown) wherein the lower ends can be lifted up by either a hydraulic cylinder (not shown) or manually.", "In the storage position, the conveyors may be pinned or otherwise secured.", "With reference now of FIG. 5, the track renewal machine 10 with anchor removers 20 is shown together with other mechanisms used in track renewal including a gantry, handling car, beam car and trailer car.", "The more specific mechanisms shown also include a central crawler (which would attach to mount 24 of FIG. 2), old sleeper or cross tie pickup, ballast spreader, new sleeper or cross tie layer, rail heater, and clip applicator.", "None of the details of these specific mechanisms need be described herein, but it is noted that the rail heater and clip applicator are described in a co-pending application entitled RAIL HEATING AND CLIP APPLICATOR, invented by the inventor herein, assigned to the assignee of the present application, filed Apr. 14, 1997, Ser.", "No. 08/839,460, and hereby incorporated herein by reference.", "FIG. 6 shows an alternate embodiment machine 110 having components in the 100 series with the same last two digits as the corresponding component(s), if any, of the embodiment of FIGS. 1-4.", "Thus, components 112, 116, 120, 130, and 148 are identical in operation and construction as components 12, 16, 20, 30, and 48.", "Indeed, machine 110 functions and is constructed the same as machine 10 except as noted hereinbelow.", "Instead of transverse conveyor 148 depositing the loose anchors at the side of the road bed, support plates 160 have collecting bins 162 mounted thereto.", "Collecting bins 162 catch anchors that come off transverse conveyor 148 by way of one of the feeder guide plates 164.", "Although specific constructions have been presented herein, it is to be understood that these are for illustrative purposes only.", "Various modifications and adaptations will be apparent to those of skill in the art.", "In view of possible modifications, it will be appreciated that the scope of the present invention should be determined by reference to the claims appended hereto." ]
FIELD OF THE INVENTION The field of this invention relates to an apparatus useful in transport and insertion of radioactive sources in suitable enclosures allowing accurate positioning of the sources while minimizing exposure to operators. BACKGROUND OF THE INVENTION Many different processes involve storage vessels to contain raw materials, finished products, bi-products, and intermediate products. Many times the storage conditions involve extremes of temperature and pressure. As part of accurate control of the process, it is desirable to know the level in the vessels and other physical properties of the materials stored therein. Many different devices have been developed to detect level and density of materials in storage vessels. One such measuring system involves the use of nuclear sources installed in wells, which are in turn mounted to the storage vessels. The wells represent an elongated space which is not in fluid communication with the contents of the vessel wherein various nuclear sources are mounted. Adjacent these sources, but outside of the vessel, are corresponding detectors which sense signals emitted by the sources. The accurate placement of sources and detectors is critical to obtaining meaningful data regarding parameters such as level in the vessel or/and physical properties of the materials within the vessel. Clearly, handling of the sources must be done very carefully to minimize exposure to the operator during installation and transport. On many occasions, the clearance available next to a well located on a vessel is limited due to obstructions by other equipment or structural members. It is therefore desirable to have a compact design for a transport enclosure for the sources so that the enclosure can be easily placed in position for insertion of the sources. Typical installations involve the placement of sources at varying depths within the well. In the past, this has been accomplished by connecting a plurality of sources to a cable, winding the cable with the sources around a drum, and enclosing the drum in a housing. Some of the disadvantages of this type of an arrangement are that the cable with sources attached becomes large and bulky when wound around a drum, necessitating the use of larger and larger housings to transport the sources to the location of use, as well as creating difficulties in actual installation due to the size of the housing used. Another problem that springs from the use of sources permanently attached to a cable is that there is no leeway in adjustment of the relative positions of the sources. Those skilled in the art can readily appreciate that when multiple sources are connected to a cable and precise alignment is required between each source and each detector on the outside of the vessel, complications can arise in obtaining overall alignment of multiple sources and detectors. Due to the permanent attachment, no fine-tuning of the relative placement of the sources is possible. A variation of the cable arrangement, previously described, has also been developed. In this arrangement, a plurality of turnbuckles are installed in the cable so that relative positional changes between the various sources connected to the cable can be made. However, the degree of adjustment is limited. The turnbuckles must be of a fairly small size so that they can wind up on the drum for installation and removal of the sources. Again, the necessity of having all of the sources premounted to a cable, even with the use of turnbuckles, still results in a housing having significant bulk. This creates problems when access to the well on a vessel is fairly limited due to the location of other equipment, utilities, or structural obstructions. To address the requirements for a compact transport housing for sources, the apparatus of the present invention has been developed. The apparatus of the present invention provides for separate storage of the sources and their supporting members from the mechanism of raising and lowering the sources. Additionally, a perforated belt is designed that has sufficient structural rigidity to support the weight of the sources, yet at the same time is sufficiently flexible so that it can be wound around the drum with the sources separately supported. The compact design of the belt and drum allows for a smaller housing to be used because the drum size is dramatically reduced. The apparatus features safety features to prevent loss of the sources in the well and premarked perforations in the belt for accurate placement of the sources. Several details of the invention also provide for easy adjustment of the source locations, as well as a mechanism for removing the source housing and installing a mounting housing to contain the excess belt extending beyond the well in the vessel. Those and another beneficial features of the invention will be described below in detail. SUMMARY OF THE INVENTION A compact design of a shielded housing for transport and insertion of radioactive sources into wells for use in measuring properties of materials in vessels and the like is disclosed in this invention. The apparatus features a perforated belt which is wound on a drum. The sources are temporarily supported within the shielded housing and can be moved into place and mounted to the belt at the desired locations. Safety features are provided to avoid dropping the sources into the well and to temporarily support the belt so that the transport housing can be removed. The invention also provides for adjustment of the mounting position of the source or sources mounted to the belt. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the housing showing the placement of the sources and the raising and lowering mechanism. FIG. 2 is a detail of the trap door assembly indicating its interconnection to the drum. FIG. 3 is the cover for the housing shown in FIG. 1. FIG. 4 is a sectional elevational view showing the drum and the sources and how they are attached to the belt. FIG. 5 shows the belt in elevation, as well as a pinch roller assembly for temporary support thereof. FIG. 6 is a sectional elevational view of the source holder. FIG. 7 is an elevational view of the lower end of the belt. FIG. 8 is an elevational view of a segment of the belt showing how the stop lock position can be adjusted. FIG. 9 is a sectional elevational view showing the stop block temporarily suspending the belt in a well after removal of the housing. FIG. 10 is an elevational view of a mounting housing which can be put on a well after the source housing shown in FIG. 1 is removed and the sources are in place. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The apparatus A of the present invention is shown in FIGS. 1, 2, and 3. The apparatus includes a housing 10 which is covered with a shield 12 preferably lead or another suitable material that can prevent the escape of harmful radiation. The housing 10 is manipulated by lifting on a bail 14 which is shown partially in FIG. 1. In essence, bale 14 is a rod that extends over the top of the housing 10 and is connected to the opposite side of housing 10. Guide tubes 13 engage rods (not shown) to align housing 10 with well 18 for attachment. This allows a hook or similar grasping device to be used to lift the entire housing 10, along with cover 16 shown in FIG. 3 into position above a well 18 (see FIG. 9). Typically, well 18 extends into a vessel or other storage container (not shown) and has an inner space 20 to accommodate belt 22 and the source holder 24 (see FIG. 4). When shipping the source holders 24 to a particular site for use in a well 18, the housing 10 has cover 16 mounted to brackets 26. A pair of pins 28 extend through openings 30 (see FIG. 1) to secure the rear of cover 16 while bolts 32, coupled with nuts 34 and washers 36 are used to secure the cover 16 to lugs 26. A door 38 is connected by hinges 40 to base 42. Thus, the apparatus A is completely enclosed during shipment due to the securing of cover 16 to base 42, and door 38 being in the closed position and secured to cover 16. A lock 44 can be inserted through opening 46 to secure door 38 in the closed position against cover 16. Housing 10 has a bottom flange, which is not shown in FIG. 1, but is similar in construction to flange 48 shown in FIG. 9. Thus, the outlet flange 48 connected to housing 10 on its underside is adapted to be directly or indirectly mounted to well 18, which is shown in FIG. 9. The apparatus of the present invention is moved into position by lifting on bail 14 and placing the outlet flange 48 into alignment with the well 18, and securing the two together with a suitable clamp or connector. At that point, the cover 16 can be removed after opening door 38. When the housing 10 is in the position for shipment, a frame 50, comprising a rear locking bar 52 and a source holder locking bar 54 and locking rods 56 is used to secure the source holders 24 in the position shown in FIG. 1. The frame 50 also includes shields 58, which are typically stainless steel encased lead. The shields 58 are shown cutaway in FIG. 1 to provide further clarity in the drawing, but are in fact continuous members that shift with respect to rods 56 when a lock (not shown) is removed from hasp 60. Removing the lock from the hasp 60 allows source holder locking bar 54 to come forward pulling forward the shields 58 so that slot 62 is exposed. It should be noted that slot 62 extends in opposite directions from well opening 64. Accordingly, with the locking rods 56 in the position shown in FIG. 1, the source holders 24 are locked in the position shown and cannot be moved into slot 62 for mounting to belt 22 lowering into well opening 64. This is because rods 59 extend through the holders of sources 24. In the open position, rods 56 no longer extend through the frames of sources 24, and shields 58 no longer block path 62. The housing 10 also features a frame 66 which holds a drum 68. Drum 68 is rotated by moving crank 70. Crank 70 can be locked into place by inserting a lock through the drum locking lever or hasp 72. Wound around drum 68 is belt 22. As shown in FIGS. 8 and 5, belt 22 has openings on repeating center lines. The openings consist of a large circle 74 (see FIG. 5) intersected by a smaller circle 76 to form one cohesive cutout which repeats itself on belt 22. Other opening shapes or methods of attachment may be used without departing from the spirit of the invention. It is desirable to get the source holders 24 from the position shown in FIG. 1 to the position shown in FIG. 4 so that they can be lowered into well 18 for use. The first step in accomplishing this is to pull back source holder locking door 54 which exposes slot 62 to opening 64. Thereafter, the sources 24 can be taken and raised up by a frame 25 (see FIG. 6) until segment 78 (see FIG. 6) of frame 25 is brought to the elevation of slot 62 for sliding therethrough into well 64. At this time, while segment 78 is translated through slot 62 toward opening 64, radioactive source 80, which is preferably held in a stainless tube with a tungsten shield, is still within the housing 10 which is fully shielded. As shown in FIG. 1, the source holders of the preferred embodiment must be rotated 90 degrees to get them to go onto belt 22. The attachment of source holder 24 to belt 22 is illustrated in FIG. 4. Each source holder has a pair of headed studs 82 which are positioned so that when placed in alignment with the openings 74 and 76 of belt 22, each headed stud 82 will project initially through the larger circular opening 74. Thereafter, the source holder is slid down so that each headed stud 82 engages the smaller circular opening 76 for support. While the insertion of the headed stud through large opening 74 and smaller opening 76 is ongoing, handle 84 is pulled back into the position shown in dashed lines in FIG. 4. Pulling back the handle 84 retracts pin 86. After the headed studs 82 have landed in the smaller opening 76, handle 84 is released. Spring 88 pushes pin 86 outwardly as shown in FIG. 4 until it occupies the larger circular opening 74 and abuts the headed stud 82. At that point in time, the source holder 24 is securely fastened to belt 22 and handle 84 is in the position shown in solid lines in FIG. 4. More of belt 22 can be played out by turning drum crank 70. As a result of turning drum crank 70, a weight 90 (see FIG. 7), which is attached to the end of belt 22, helps to pull the belt downwardly into the well 18 (see FIG. 9). Rotation of crank 70 allows the weight 90 to go through opening 64. Thereafter, at selective hole locations on belt 22, the appropriate source holder 24 can be moved through slot 62 into position for mounting according to the procedure previously described and shown in FIG. 4. A belt support bracket 92 backs up belt 22 so that when the headed studs 82 are pushed through large opening 74 to be secured into smaller opening 76 adjacent thereto, the belt is supported to facilitate the attachment process. The apparatus A of the present invention also has a feature to prevent dropping the source holders 24 into space 20 of well 18 (see FIG. 9). Referring to FIGS. 1 and 2, there is a safety door 94 which is shown in the closed position in FIG. 1. With door 94 in the position shown in FIG. 1, the upper end of the source holders 24 cannot fit down opening 64. When it is desired to lower a source holder 24 beneath opening 64, lever 96 is actuated which on the one hand releases pawl 98. Pawl 98 is normally engaged to ratchet wheel 100 so as to prevent downward progress of tape 22 into well 18 unless the pawl 98 is released from contact from ratchet wheel 100 due to the operation of lever 96. As seen in FIGS. 1 and 2, pulling upwardly or in a clockwise direction on lever 96 pulls up link 102 which is in turn pivotally mounted to rod 104 which is connected to door 94. Door 94 is biased to a closed position by spring 106. Accordingly, the procedure is to strongly secure a source holder 24 to belt 22 by the method previously described and illustrated in FIG. 4. Thereafter, lever 96 is actuated and while it is held up, crank 70 is rotated to lower the belt further into well 18 to facilitate placement of additional sources. Having reached the point of accurately placing each source on the belt with the proper spacing, it is desirable to suspend belt 22 in space 20 of well 18 (see FIG. 8). First, an upper stop block 109 is attached to belt 22 to support it from rollers 114 and 116. The housing 10 is lifted and a lower stop block 108 is attached to belt 22. Lower stop block 108 has a pair of pins 110 and 112 which are spaced the same distance as a pair of adjacent circular openings 74. Using pins 110 and 112, the lower stop block 108 is attached to belt 22 and ultimately comes to rest inside the opening 20 of well 18. If the suspension point of the sources 24 needs to be changed by moving the entire belt 22, this can be readily accomplished as shown in FIG. 8. Belt 22 is raised until lower stop block 108 is readily accessible. At that time, if the block needs to be lowered, thereby raising belt 22, pin 110 is pulled out and the block is rotated about pin 112 until pin 110 engages the next lower opening as illustrated in FIG. 8. The rotation can be reversed to effectively raise the lower stop block 106 with respect to belt 22 by leaving pin 110 secure while undoing pin 112 and rotating the lower stop block 108 upwardly until pin 112 can be reinserted into the next highest circular opening 74. While the lower stop block 108 is being secured, belt 22 is independently supported separately from upper stop block 109. This is best shown in FIGS. 1, 4, and 5. As seen in FIG. 1, belt 22 travels between a pair of rollers 114 and 116. Rollers 114 and 116 are supported in a guide roller assembly 118 and are capable of translating in the two positions in FIG. 5. The rollers 114 and 116 are mounted to pins 120 and 122, respectively. Springs 124 and 126 bias the rollers 114 and 116 into the position shown in FIG. 1 where upper stop block 109 rests against rollers 114 and 116 to effectively support belt 22 on the guide roller assembly 118. Thereafter, the remaining portions of belt 22 are played out of drum 68, and belt 22 is detached from the drum 68 by moving rollers 114 and 116 to the side while leaving upper stop block 109 on belt 22. Belt 22 is marked so that placement of lower stop block 108 is guided by the location of upper stop block 109 on belt 22. Housing 10 can be removed from well 18 with upper stop block 109 still attached. This also facilitates accurate sources 24 placement on reinsertion of the sources 24 after maintenance procedures. While this procedure is going on, it is preferred to have lower stop block 108 firmly in position supporting belt 22 within space 20 of well 18 as shown in FIG. 9. Having ensured that belt 22 is firmly supported by stop lock 108, the housing 10 can be removed after belt 22 is detached from drum 68. At this point, the rollers 114 and 116 are moved to the dashed position shown in FIG. 5 where they no longer support belt 22. Accordingly, the guide roller assembly 118 is a temporary support for belt 122 used during the removal process for housing 10. Having removed the housing 10 at flange 48, the remaining segment of belt 22 is straightened as shown in FIG. 10 and a housing 128 is placed over the extended section of belt 22 above lower stop block 108. For clarity, lower stop block 108 is not illustrated in FIG. 10. Those skilled in the art can appreciate that various means of attachment to belt 22 can be employed. It is the separate mounting of the sources 24 and the means of attachment to belt 22 as the belt is being lowered into well 18 that allows the use of a compact drum 68 and as a result a more compact housing 10. While a safety door 94 is illustrated, various other means of preventing the sources 24 from falling through opening 64 can be employed without departing from the spirit of the invention. Various different materials can be used for the components; however, the preferred embodiment for the belt is inconel and the preferred materials for the source holder are stainless steel in combination with a shield about source 130 (see FIG. 6) made of tungsten. The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made without departing from the spirit of the invention.
A compact design of a shielded housing for transport and insertion of radioactive sources into wells for use in measuring properties of materials in vessels and the like is disclosed in this invention. The apparatus features a perforated belt which is wound on a drum. The sources are temporarily supported within the shielded housing and can be moved into place and mounted to the belt at the desired locations. Safety features are provided to avoid dropping the sources into the well and to temporarily support the belt so that the transport housing can be removed. The invention also provides for adjustment of the mounting height of the source or sources mounted to the belt.
Summarize the information, clearly outlining the challenges and proposed solutions.
[ "FIELD OF THE INVENTION The field of this invention relates to an apparatus useful in transport and insertion of radioactive sources in suitable enclosures allowing accurate positioning of the sources while minimizing exposure to operators.", "BACKGROUND OF THE INVENTION Many different processes involve storage vessels to contain raw materials, finished products, bi-products, and intermediate products.", "Many times the storage conditions involve extremes of temperature and pressure.", "As part of accurate control of the process, it is desirable to know the level in the vessels and other physical properties of the materials stored therein.", "Many different devices have been developed to detect level and density of materials in storage vessels.", "One such measuring system involves the use of nuclear sources installed in wells, which are in turn mounted to the storage vessels.", "The wells represent an elongated space which is not in fluid communication with the contents of the vessel wherein various nuclear sources are mounted.", "Adjacent these sources, but outside of the vessel, are corresponding detectors which sense signals emitted by the sources.", "The accurate placement of sources and detectors is critical to obtaining meaningful data regarding parameters such as level in the vessel or/and physical properties of the materials within the vessel.", "Clearly, handling of the sources must be done very carefully to minimize exposure to the operator during installation and transport.", "On many occasions, the clearance available next to a well located on a vessel is limited due to obstructions by other equipment or structural members.", "It is therefore desirable to have a compact design for a transport enclosure for the sources so that the enclosure can be easily placed in position for insertion of the sources.", "Typical installations involve the placement of sources at varying depths within the well.", "In the past, this has been accomplished by connecting a plurality of sources to a cable, winding the cable with the sources around a drum, and enclosing the drum in a housing.", "Some of the disadvantages of this type of an arrangement are that the cable with sources attached becomes large and bulky when wound around a drum, necessitating the use of larger and larger housings to transport the sources to the location of use, as well as creating difficulties in actual installation due to the size of the housing used.", "Another problem that springs from the use of sources permanently attached to a cable is that there is no leeway in adjustment of the relative positions of the sources.", "Those skilled in the art can readily appreciate that when multiple sources are connected to a cable and precise alignment is required between each source and each detector on the outside of the vessel, complications can arise in obtaining overall alignment of multiple sources and detectors.", "Due to the permanent attachment, no fine-tuning of the relative placement of the sources is possible.", "A variation of the cable arrangement, previously described, has also been developed.", "In this arrangement, a plurality of turnbuckles are installed in the cable so that relative positional changes between the various sources connected to the cable can be made.", "However, the degree of adjustment is limited.", "The turnbuckles must be of a fairly small size so that they can wind up on the drum for installation and removal of the sources.", "Again, the necessity of having all of the sources premounted to a cable, even with the use of turnbuckles, still results in a housing having significant bulk.", "This creates problems when access to the well on a vessel is fairly limited due to the location of other equipment, utilities, or structural obstructions.", "To address the requirements for a compact transport housing for sources, the apparatus of the present invention has been developed.", "The apparatus of the present invention provides for separate storage of the sources and their supporting members from the mechanism of raising and lowering the sources.", "Additionally, a perforated belt is designed that has sufficient structural rigidity to support the weight of the sources, yet at the same time is sufficiently flexible so that it can be wound around the drum with the sources separately supported.", "The compact design of the belt and drum allows for a smaller housing to be used because the drum size is dramatically reduced.", "The apparatus features safety features to prevent loss of the sources in the well and premarked perforations in the belt for accurate placement of the sources.", "Several details of the invention also provide for easy adjustment of the source locations, as well as a mechanism for removing the source housing and installing a mounting housing to contain the excess belt extending beyond the well in the vessel.", "Those and another beneficial features of the invention will be described below in detail.", "SUMMARY OF THE INVENTION A compact design of a shielded housing for transport and insertion of radioactive sources into wells for use in measuring properties of materials in vessels and the like is disclosed in this invention.", "The apparatus features a perforated belt which is wound on a drum.", "The sources are temporarily supported within the shielded housing and can be moved into place and mounted to the belt at the desired locations.", "Safety features are provided to avoid dropping the sources into the well and to temporarily support the belt so that the transport housing can be removed.", "The invention also provides for adjustment of the mounting position of the source or sources mounted to the belt.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the housing showing the placement of the sources and the raising and lowering mechanism.", "FIG. 2 is a detail of the trap door assembly indicating its interconnection to the drum.", "FIG. 3 is the cover for the housing shown in FIG. 1. FIG. 4 is a sectional elevational view showing the drum and the sources and how they are attached to the belt.", "FIG. 5 shows the belt in elevation, as well as a pinch roller assembly for temporary support thereof.", "FIG. 6 is a sectional elevational view of the source holder.", "FIG. 7 is an elevational view of the lower end of the belt.", "FIG. 8 is an elevational view of a segment of the belt showing how the stop lock position can be adjusted.", "FIG. 9 is a sectional elevational view showing the stop block temporarily suspending the belt in a well after removal of the housing.", "FIG. 10 is an elevational view of a mounting housing which can be put on a well after the source housing shown in FIG. 1 is removed and the sources are in place.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The apparatus A of the present invention is shown in FIGS. 1, 2, and 3.", "The apparatus includes a housing 10 which is covered with a shield 12 preferably lead or another suitable material that can prevent the escape of harmful radiation.", "The housing 10 is manipulated by lifting on a bail 14 which is shown partially in FIG. 1. In essence, bale 14 is a rod that extends over the top of the housing 10 and is connected to the opposite side of housing 10.", "Guide tubes 13 engage rods (not shown) to align housing 10 with well 18 for attachment.", "This allows a hook or similar grasping device to be used to lift the entire housing 10, along with cover 16 shown in FIG. 3 into position above a well 18 (see FIG. 9).", "Typically, well 18 extends into a vessel or other storage container (not shown) and has an inner space 20 to accommodate belt 22 and the source holder 24 (see FIG. 4).", "When shipping the source holders 24 to a particular site for use in a well 18, the housing 10 has cover 16 mounted to brackets 26.", "A pair of pins 28 extend through openings 30 (see FIG. 1) to secure the rear of cover 16 while bolts 32, coupled with nuts 34 and washers 36 are used to secure the cover 16 to lugs 26.", "A door 38 is connected by hinges 40 to base 42.", "Thus, the apparatus A is completely enclosed during shipment due to the securing of cover 16 to base 42, and door 38 being in the closed position and secured to cover 16.", "A lock 44 can be inserted through opening 46 to secure door 38 in the closed position against cover 16.", "Housing 10 has a bottom flange, which is not shown in FIG. 1, but is similar in construction to flange 48 shown in FIG. 9. Thus, the outlet flange 48 connected to housing 10 on its underside is adapted to be directly or indirectly mounted to well 18, which is shown in FIG. 9. The apparatus of the present invention is moved into position by lifting on bail 14 and placing the outlet flange 48 into alignment with the well 18, and securing the two together with a suitable clamp or connector.", "At that point, the cover 16 can be removed after opening door 38.", "When the housing 10 is in the position for shipment, a frame 50, comprising a rear locking bar 52 and a source holder locking bar 54 and locking rods 56 is used to secure the source holders 24 in the position shown in FIG. 1. The frame 50 also includes shields 58, which are typically stainless steel encased lead.", "The shields 58 are shown cutaway in FIG. 1 to provide further clarity in the drawing, but are in fact continuous members that shift with respect to rods 56 when a lock (not shown) is removed from hasp 60.", "Removing the lock from the hasp 60 allows source holder locking bar 54 to come forward pulling forward the shields 58 so that slot 62 is exposed.", "It should be noted that slot 62 extends in opposite directions from well opening 64.", "Accordingly, with the locking rods 56 in the position shown in FIG. 1, the source holders 24 are locked in the position shown and cannot be moved into slot 62 for mounting to belt 22 lowering into well opening 64.", "This is because rods 59 extend through the holders of sources 24.", "In the open position, rods 56 no longer extend through the frames of sources 24, and shields 58 no longer block path 62.", "The housing 10 also features a frame 66 which holds a drum 68.", "Drum 68 is rotated by moving crank 70.", "Crank 70 can be locked into place by inserting a lock through the drum locking lever or hasp 72.", "Wound around drum 68 is belt 22.", "As shown in FIGS. 8 and 5, belt 22 has openings on repeating center lines.", "The openings consist of a large circle 74 (see FIG. 5) intersected by a smaller circle 76 to form one cohesive cutout which repeats itself on belt 22.", "Other opening shapes or methods of attachment may be used without departing from the spirit of the invention.", "It is desirable to get the source holders 24 from the position shown in FIG. 1 to the position shown in FIG. 4 so that they can be lowered into well 18 for use.", "The first step in accomplishing this is to pull back source holder locking door 54 which exposes slot 62 to opening 64.", "Thereafter, the sources 24 can be taken and raised up by a frame 25 (see FIG. 6) until segment 78 (see FIG. 6) of frame 25 is brought to the elevation of slot 62 for sliding therethrough into well 64.", "At this time, while segment 78 is translated through slot 62 toward opening 64, radioactive source 80, which is preferably held in a stainless tube with a tungsten shield, is still within the housing 10 which is fully shielded.", "As shown in FIG. 1, the source holders of the preferred embodiment must be rotated 90 degrees to get them to go onto belt 22.", "The attachment of source holder 24 to belt 22 is illustrated in FIG. 4. Each source holder has a pair of headed studs 82 which are positioned so that when placed in alignment with the openings 74 and 76 of belt 22, each headed stud 82 will project initially through the larger circular opening 74.", "Thereafter, the source holder is slid down so that each headed stud 82 engages the smaller circular opening 76 for support.", "While the insertion of the headed stud through large opening 74 and smaller opening 76 is ongoing, handle 84 is pulled back into the position shown in dashed lines in FIG. 4. Pulling back the handle 84 retracts pin 86.", "After the headed studs 82 have landed in the smaller opening 76, handle 84 is released.", "Spring 88 pushes pin 86 outwardly as shown in FIG. 4 until it occupies the larger circular opening 74 and abuts the headed stud 82.", "At that point in time, the source holder 24 is securely fastened to belt 22 and handle 84 is in the position shown in solid lines in FIG. 4. More of belt 22 can be played out by turning drum crank 70.", "As a result of turning drum crank 70, a weight 90 (see FIG. 7), which is attached to the end of belt 22, helps to pull the belt downwardly into the well 18 (see FIG. 9).", "Rotation of crank 70 allows the weight 90 to go through opening 64.", "Thereafter, at selective hole locations on belt 22, the appropriate source holder 24 can be moved through slot 62 into position for mounting according to the procedure previously described and shown in FIG. 4. A belt support bracket 92 backs up belt 22 so that when the headed studs 82 are pushed through large opening 74 to be secured into smaller opening 76 adjacent thereto, the belt is supported to facilitate the attachment process.", "The apparatus A of the present invention also has a feature to prevent dropping the source holders 24 into space 20 of well 18 (see FIG. 9).", "Referring to FIGS. 1 and 2, there is a safety door 94 which is shown in the closed position in FIG. 1. With door 94 in the position shown in FIG. 1, the upper end of the source holders 24 cannot fit down opening 64.", "When it is desired to lower a source holder 24 beneath opening 64, lever 96 is actuated which on the one hand releases pawl 98.", "Pawl 98 is normally engaged to ratchet wheel 100 so as to prevent downward progress of tape 22 into well 18 unless the pawl 98 is released from contact from ratchet wheel 100 due to the operation of lever 96.", "As seen in FIGS. 1 and 2, pulling upwardly or in a clockwise direction on lever 96 pulls up link 102 which is in turn pivotally mounted to rod 104 which is connected to door 94.", "Door 94 is biased to a closed position by spring 106.", "Accordingly, the procedure is to strongly secure a source holder 24 to belt 22 by the method previously described and illustrated in FIG. 4. Thereafter, lever 96 is actuated and while it is held up, crank 70 is rotated to lower the belt further into well 18 to facilitate placement of additional sources.", "Having reached the point of accurately placing each source on the belt with the proper spacing, it is desirable to suspend belt 22 in space 20 of well 18 (see FIG. 8).", "First, an upper stop block 109 is attached to belt 22 to support it from rollers 114 and 116.", "The housing 10 is lifted and a lower stop block 108 is attached to belt 22.", "Lower stop block 108 has a pair of pins 110 and 112 which are spaced the same distance as a pair of adjacent circular openings 74.", "Using pins 110 and 112, the lower stop block 108 is attached to belt 22 and ultimately comes to rest inside the opening 20 of well 18.", "If the suspension point of the sources 24 needs to be changed by moving the entire belt 22, this can be readily accomplished as shown in FIG. 8. Belt 22 is raised until lower stop block 108 is readily accessible.", "At that time, if the block needs to be lowered, thereby raising belt 22, pin 110 is pulled out and the block is rotated about pin 112 until pin 110 engages the next lower opening as illustrated in FIG. 8. The rotation can be reversed to effectively raise the lower stop block 106 with respect to belt 22 by leaving pin 110 secure while undoing pin 112 and rotating the lower stop block 108 upwardly until pin 112 can be reinserted into the next highest circular opening 74.", "While the lower stop block 108 is being secured, belt 22 is independently supported separately from upper stop block 109.", "This is best shown in FIGS. 1, 4, and 5.", "As seen in FIG. 1, belt 22 travels between a pair of rollers 114 and 116.", "Rollers 114 and 116 are supported in a guide roller assembly 118 and are capable of translating in the two positions in FIG. 5. The rollers 114 and 116 are mounted to pins 120 and 122, respectively.", "Springs 124 and 126 bias the rollers 114 and 116 into the position shown in FIG. 1 where upper stop block 109 rests against rollers 114 and 116 to effectively support belt 22 on the guide roller assembly 118.", "Thereafter, the remaining portions of belt 22 are played out of drum 68, and belt 22 is detached from the drum 68 by moving rollers 114 and 116 to the side while leaving upper stop block 109 on belt 22.", "Belt 22 is marked so that placement of lower stop block 108 is guided by the location of upper stop block 109 on belt 22.", "Housing 10 can be removed from well 18 with upper stop block 109 still attached.", "This also facilitates accurate sources 24 placement on reinsertion of the sources 24 after maintenance procedures.", "While this procedure is going on, it is preferred to have lower stop block 108 firmly in position supporting belt 22 within space 20 of well 18 as shown in FIG. 9. Having ensured that belt 22 is firmly supported by stop lock 108, the housing 10 can be removed after belt 22 is detached from drum 68.", "At this point, the rollers 114 and 116 are moved to the dashed position shown in FIG. 5 where they no longer support belt 22.", "Accordingly, the guide roller assembly 118 is a temporary support for belt 122 used during the removal process for housing 10.", "Having removed the housing 10 at flange 48, the remaining segment of belt 22 is straightened as shown in FIG. 10 and a housing 128 is placed over the extended section of belt 22 above lower stop block 108.", "For clarity, lower stop block 108 is not illustrated in FIG. 10.", "Those skilled in the art can appreciate that various means of attachment to belt 22 can be employed.", "It is the separate mounting of the sources 24 and the means of attachment to belt 22 as the belt is being lowered into well 18 that allows the use of a compact drum 68 and as a result a more compact housing 10.", "While a safety door 94 is illustrated, various other means of preventing the sources 24 from falling through opening 64 can be employed without departing from the spirit of the invention.", "Various different materials can be used for the components;", "however, the preferred embodiment for the belt is inconel and the preferred materials for the source holder are stainless steel in combination with a shield about source 130 (see FIG. 6) made of tungsten.", "The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made without departing from the spirit of the invention." ]
CROSS-REFERENCE TO RELATED APPLICATION The subject matter of this application is related to the subject matter of commonly assigned, co-pending Application No. 60/125,811, filed Mar. 23, 1999, priority to which is claimed under 35 U.S.C. §119(e) and which is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates generally to improving airflow in heat and mass transfer processes such as baking, freezing or drying and, more particularly, to improving impingement airflow by way of air fluctuation, increased airflow uniformity, and enhanced control of airflow. Embodiments of the invention are particularly applicable to use with ovens designed for baking pizza, especially restaurant ovens that can utilize the limited space available more efficiently and operate more quietly for a more compatible working environment. 2. Description of Related Art Impingement processing that achieves heat and mass transfer modification of products is particularly attractive because impinging jets of air disrupt the layers of stagnant gas surrounding the surface of a product, thus increasing convection heat and mass transfer. The latter may also be increased by: vibration and pulsation of sound waves, rifling of air jets to be more cylindrical and less conical, rotating a jet about its axis, or swirling an air jet. See Huang, L. et al, “Heat Transfer and Flow Visualization Experiments of Swirling, Multi-Channel, and Conventional Impinging Jets,” Int. J. Heat Mass Transfer , Vol. 41, No.3, pp.583-600 (1998), incorporated herein by reference, and placing a return air duct adjacent to air jet nozzles to make the jets more effective as described with respect to FIG. 1 of U.K. Patent No. 914,546, also incorporated herein by reference. Many impingement ovens, for example, are hampered by a lack of uniformity of airflow due to design limitations. Nonuniform impingement airflow can cause irregularities within the oven, within baked products and between products being cooked at the same time. For example, the right-hand side of a pizza may be more baked than the left-hand side in some instances of nonuniform airflow, or identical raw pizzas may be baked to differing degrees in different zones of the same oven. Three important types of nonuniformity that adversely affect heat and mass transfer are: (1) differences in absolute air velocity at different nozzles due to irregular air flow into and out of the plenum chambers; (2) discharge of air from the nozzles in a non-perpendicular orientation to the surface of the heat and mass transfer modified product; and (3) tendency of the air jets to fan out into a widening cone more quickly than desired. Past heat and mass transfer impingement devices have attempted to compensate for some of these deficiencies by passing air through long, thin, straight pipes which can impart a rifling effect to the discharged air. Air flowing through the pipes meets resistance to flow and experiences a pressure differential across the pipes. Expanding the pipe length aids in equilibrating the discharged air flowing from the pipes. Such processing equipment, however, tends to be very large and requires pipe lengths ranging from about 50-60 centimeters with pipe diameters of approximately two centimeters. Impinging jets of gas in an oven can be expelled through nozzles in pipes through which gasflows under pressure, as described in U.K. Patent No. 985,443, incorporated herein by reference. Also, a high velocity jet of gas, so propelled, can be used to propel the flow of other gases by applying the Venturi effect, as exemplified by Newberry, Desmond, “Vacuum Cooling,” in Proceedings of 72 nd Annual Conference of the American Society of Bakery Engineers , Chicago, Ill., pp. 81-86, (March 1996), incorporated herein by reference. In both cases, airflow can be quieter and better controlled than with the use of plenum chambers into which air is propelled with the help of large fans and large air-circulation chambers. This is because the propulsion of gas under pressure can be regulated more conveniently by the adjustment of a valve opening than by the modulation of fan speed, without the inherent complexities of aerodynamic airflow within large chambers and the noise of the fan and said airflow within said chambers. Accordingly, an impingement system that uses compressed air in pipes with nozzles, or uses air propelled by the Venturi mechanism, promises to be quieter, more compact, and more easily controlled than circulating air with fans into plenum chambers. One particular shortcoming of the prior art that is addressed by embodiments of the invention is the inability to employ impingement processing more effectively in applications where it is desirable to cook a baked product, such as pizza, traveling through the oven on a conveyor belt within the limiting space constraints of a restaurant kitchen. Even in those instances where a conveyor belt is used, only a single rack per oven would be feasible because of the blocking that would occur between vertically spaced baked products in typical ovens. Examples of ovens utilizing single-layer conveyor belts for cooking can be found in Ovadia, David Z., et al., “Impingement in Food Processing,” Food Technology , Vol. 52, No.4, pp. 46-50 (April 1998), incorporated herein by reference. SUMMARY OF THE INVENTION Embodiments of the present invention are contemplated for use in situations wherein heat and mass transfer modified product, such as individual-sized pizzas, are to be prepared in relatively short periods of time, for example in one to five minutes. Through e.g. structural design features and air manipulation, embodiments of the invention provide distinct advantages over the prior art, including improving quality control by increasing uniformity of heating across the oven and within each particular product, decreasing required baking time by increasing the effectiveness of impinging air jets through air pulsation and fluctuation, and maintaining uniformity of air flow to contact the baked product substantially perpendicular to its surface. Also, the use of tubes, or pipes possessing impingement nozzles described in the following, permits the use of compressed air instead of fans and the implementation of related advantages, permitting more compact oven design, better control of air jet parameters, and quieter oven operation, for example. To overcome disadvantages of the prior art, embodiments of the invention utilize multiple short, thin, straight pipes to effect a columnar airflow which strikes perpendicularly to the surface of the heat and transfer modified product. The pipes are configured to achieve a predetermined ratio of length to diameter and desired pressure differentials across the respective pipes. A multiplicity of smaller adjacent pipes is used to facilitate a compact oven, while maintaining the appropriate length-to-diameter ratio necessary for the rifling of impinging jets. While said smaller pipes may be straight, they may also be spiraled to create swirled jet flow. Alternatively, pipes of substantially equal total length are configured to effect heating wherein one or a set of the pipes are folded back upon themselves or otherwise configured to facilitate a compact-sized heat and mass transfer processing device, such as an oven. In another embodiment, variations in air fluctuation are effected with a shutter, flap, or other mechanism used to alternately route air through airflow conduits to different plenums or areas within the processing chamber to improve and accelerate heat and mass transfer. In one embodiment, a solenoid is employed to alternately open and close two channels through which air is alternately directed. In a further embodiment, a low-frequency whistle mechanism is placed opposite the flow of air being channeled into the processing cavity, but proximal to the plenums or other areas within the processing chamber to create low-frequency air vibration, thereby causing increased fluctuation in the airflow. Although embodiments of the invention are especially well-suited to preparation of individual-sized pizzas, the invention is not limited to these embodiments. Larger pizzas, other pizza-type and pizza-related food products, and other food and non-food products (e.g., drying paper, textiles, wood and curing electronic circuit boards, etc.) also can be prepared according to embodiments of the invention. More specifically, a nozzle insert according to an embodiment of the invention is for an impingement oven, the nozzle insert comprising an outer shell, connection structure, operably coupleable with the outer shell, constructed to position the nozzle insert to direct gasflow toward a processing chamber of an impingement oven, and a plurality of conduits disposed within the outer shell, the plurality of conduits being constructed to create a rifling effect on gasflow passing through the plurality of conduits, thereby creating a plurality of gas jets for impinging on a product in the processing chamber. The outer shell is generally cylindrical, according to one embodiment, and the plurality of conduits comprises a plurality of generally cylindrical tubes. The connection structure can be constructed to removably connect the nozzle insert in position within the oven. According to one embodiment, the outer shell has an overall length of between about 2 cm and about 5 cm, and the plurality of conduits each have a diameter of between about 0.1 and 0.2 cm. The nozzle insert preferably creates a pressure differential between a processing-chamber end thereof and an opposite end thereof, the pressure differential being generally the same as that created by a single conduit having a length up to about 12 times longer than the outer shell and having a diameter up to about 10 times the diameter of the plurality of conduits. The connection structure is constructed to removably connect the nozzle insert to a nozzle of the impingement oven, according to one embodiment, and the plurality of conduits are generally straight and provide a generally linear gasflow path. Alternatively, the plurality of conduits can be generally curved and provide a generally spiral gasflow path. Further, according to one embodiment the connection structure is constructed to connect the nozzle insert to a plenum of the impingement oven. According to an alternative embodiment of the invention, an impingement oven includes a processing chamber and a plurality of nozzle inserts positioned to direct gasflow to the processing chamber, each nozzle insert comprising an outer shell, connection structure, operably coupleable with the outer shell, constructed to position the nozzle insert to direct gasflow toward the processing chamber of the impingement oven, and a plurality of conduits disposed within the outer shell, the plurality of conduits being constructed to create a rifling effect on gasflow passing through the plurality of conduits, thereby creating a plurality of gas jets for impinging on a product in the processing chamber. According to an alternative embodiment of the invention, an impingement oven comprises a source of gas and a plurality of conduits constructed to direct heated gas from the source to a processing chamber within the oven, the plurality of conduits further being constructed to direct impinging gas to a product within the processing chamber, the plurality of conduits terminating at the processing chamber at different distances from the source; the plurality of conduits each having generally the same length. At least one of the conduits can fold back on itself between the source and the processing chamber. The impingement oven can further comprise a plurality of return conduits constructed to direct return gas from the processing chamber to the source, the return conduits originating at the processing chamber at different distances from the source, the return conduits each having generally the same length. At least one of the return conduits can fold back on itself between the processing chamber and the source. The impingement oven can further include at least one nozzle insert, in fluid communication with at least one of the conduits, the at least one nozzle insert being positioned to direct gasflow to the processing chamber, the at least one nozzle insert comprising, an outer shell, connection structure, operably coupleable with the outer shell, constructed to position the nozzle insert to direct gasflow toward the processing chamber of the impingement oven, and a plurality of subconduits disposed within the outer shell, the plurality of subconduits being constructed to create a rifling effect on gasflow passing through the plurality of subconduits, thereby creating a plurality of gas jets for impinging on the product within the processing chamber. According to an alternative embodiment, an impingement oven comprises a processing chamber, first structure at the processing chamber for directing impinging gas to a product in the processing chamber, second structure at the processing chamber for directing impinging gas to the product in the processing chamber, a gas source in fluid communication with the first and second structures, conduits for directing gas from the gas source to the first structure and the second structure and a gas fluctuation device, operably coupled with the conduits, for alternately channeling gas either to the first structure or to the second structure. The first structure can comprise a plurality of nozzles of the impingement oven, and the plurality of nozzles can be a plurality of first nozzles. The second structure can comprise a plurality of second nozzles of the impingement oven, wherein the second nozzles are disposed on an opposite side of the processing chamber from the first nozzles. The first structure comprises a plenum plate of the impingement oven, according to one embodiment, and the second structure comprises the plenum plate or an additional plenum plate of the impingement oven. The first structure can comprise a plurality of first nozzles and the second structure a plurality of second nozzles, the first nozzles being interspersed with the second nozzles. The first and/or second structure comprises at least one nozzle insert, according to one embodiment, in fluid communication with at least one of the conduits, the at least one nozzle insert being positioned to direct gasflow to the processing chamber, the at least one nozzle insert comprising an outer shell, connection structure, operably coupleable with the outer shell, constructed to position the nozzle insert to direct gasflow toward the processing chamber of the impingement oven, and a plurality of subconduits disposed within the outer shell, the plurality of subconduits being constructed to create a rifling effect on gasflow passing through the plurality of subconduits, thereby creating a plurality of gas jets for impinging on the product within the processing chamber. The gas source can comprise a source of compressed air, and the gas fluctuation device can comprise a shutter, the shutter moving to a first position to direct gas to the first structure and moving to a second position to direct gas to the second structure. The shutter can comprise a pivoted flap, and can define at least one aperture therethrough for allowing gas to flow alternately to the first structure and the second structure. The shutter can define a generally circular shape and define a plurality of apertures disposed therethrough, and the oven further can comprise a shutter plate operably connected to the shutter, rotation of the shutter plate with respect to the shutter allowing gas to flow through the apertures alternately to the first structure and the second structure. The shutter is constructed for linear movement between the first and second positions, according to one embodiment. The gas fluctuation device also can comprise at least one reciprocating piston in fluid communication with at least one of the conduits. The conduits can comprise a first conduit in fluid communication with the first structure and a second conduit in fluid communication with the second structure, and the gas fluctuation device can comprise a first reciprocating piston in fluid communication with the first conduit, and a second reciprocating piston in fluid communication with the second conduit. The first and second structure can comprise a plurality of nozzles. The oven further can comprise a plurality of valves, in fluid communication with the first and second conduits, for aiding the gas fluctuation device. The conduits comprise at least one first conduit constructed to direct gas from the source toward the processing chamber, according to one embodiment, and at least one second conduit constructed to direct gas from the processing chamber toward the source. The gas fluctuation device reverses gasflow within the oven such that the first conduit also directs gas from the processing chamber toward the source and such that the second conduit also directs gas from the source toward the processing chamber. The conduits terminate at the processing chamber at different distances from the source, according to one embodiment; the plurality of conduits each having generally the same length. Additionally, structure for producing low-frequency vibration also can be provided. According to another embodiment of the invention, an impingement oven comprises a processing chamber, first means at the processing chamber for directing impinging gas to a product in the processing chamber, second means at the processing chamber for directing impinging gas to the product in the processing chamber, means for providing a source of gas, means for directing gas from the means for providing to the first means and the second means, and means for alternately channeling gas either to the first means or to the second means. According to another embodiment of the invention, an impingement oven comprises a processing chamber, a gas source, an input channel for directing gas from the source toward the processing chamber, and a return channel for directing gas from the processing chamber toward the source, wherein at least one of the input channel and the output channel are constructed to support a product to be processed by the oven in the processing chamber. The processing chamber is constructed to accommodate multiple products top-to-bottom within the processing chamber, according to one embodiment, and the oven further comprises multiple input channels disposed directly above and directly below each product within the processing chamber. The product can be supported on the output channel. The oven further can comprise structure to reverse the flow of gas in the input channel and the output channel, such that the input channel directs gas from the processing chamber toward the source and the return channel directs gas from the source toward the processing chamber. The gas source can comprise a compressed gas source, and the structure to reverse can comprise at least one valve associated with the compressed gas source. According to another embodiment of the invention, an impingement oven comprises a processing chamber for accommodating a product to be processed by the oven, a gas source, an input channel for directing gas from the source toward the processing chamber, and a return channel for directing gas from the processing chamber toward the source, the input channel and the return channel comprising tubes disposed within the processing chamber in direct association with the product. The oven can comprise structure to reverse the flow of gas in the input channel and the output channel, such that the input channel directs gas from the processing chamber toward the source and the return channel directs gas from the source toward the processing chamber. The input channel can comprise at least one nozzle aimed toward the product for directing gas toward the product, and the return channel can comprise at least one aperture aimed away from the product for receiving return air from the processing chamber. Both the input channel and the return channel are disposed above the product, according to one embodiment, and the input channel can be disposed below the product and comprise at least one nozzle aimed away from the product. A second input channel can be disposed above the product, the second input channel comprising at least one nozzle aimed toward the product. A rebound plate for receiving and reflecting gas received from the at least one nozzle can also be provided. The gas source can be a compressed gas source. The input channel can comprise at least one nozzle, and the oven further can comprise a heating element disposed around the at least one nozzle for improving heat transfer within the oven. The heating element can comprise an electric coil or an infrared heating element, for example. The oven can comprise two input channels disposed within the processing chamber for directing gas toward the product at different distances from the source, and the two input channels can each have generally the same length. One of the input channels folds back upon itself, according to one embodiment, and at least one of the input channel and the return channel contacts the product. Other features and advantages of the invention will be apparent from the following description and claims. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will be described with respect to the figures, in which like reference numerals denote like elements, and in which: FIG. 1 shows a typical rifled nozzle. FIGS. 2-3 show an embodiment of the invention utilizing a pipe configuration to improve impingement airflow. FIGS. 4-6 show insertion of the FIG. 2 embodiment into an existing nozzle according to an embodiment of the invention. FIG. 7 shows an airflow path according to the FIG. 2 embodiment. FIGS. 8-9 show airflow paths according to an alternative embodiment. FIG. 10 shows an embodiment of the invention utilizing an alternative pipe configuration to improve impingement airflow. FIG. 11 shows an embodiment of the invention utilizing air fluctuation to improve baking characteristics. FIG. 12 shows an alternative embodiment of the invention utilizing air fluctuation to improve baking characteristics. FIG. 13 shows an alternative embodiment of the invention utilizing air fluctuation to improve baking characteristics. FIG. 14 shows an alternative embodiment of the invention utilizing air fluctuation to improve baking characteristics. FIG. 15 shows an embodiment of the invention utilizing air fluctuation to improve baking characteristics. FIG. 16 shows an embodiment of the invention using low-frequency sound waves to cause air fluctuation. FIG. 17 shows an embodiment of the invention utilizing baking racks and impingement heating. FIG. 18 is a side view of the embodiment depicted in FIG. 17 . FIG. 19 is a view of the embodiment depicted in FIG. 17, utilizing an alternative method of redirecting impingement airflow. FIGS. 20-21 are side and end views, respectively, of an embodiment of the invention utilizing baking racks to effect impingement heating. FIG. 22 is a view of an embodiment of the invention depicting individual heating elements in association with heating conduits. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Embodiments of the invention provide devices and methods for improving impingement airflow in baking ovens by manipulation of the design and/or structure of heating conduits, piping and/or air nozzles, and/or or by utilization of air fluctuation techniques and designs. Embodiments of the invention are designed: (1) to equalize air speed from different nozzles into and out of the plenums or other chambers of an oven, (2) to ensure the maintenance of a substantially perpendicular orientation between the propelled jets of air from the nozzles and the surface of the baked good being heated, (3) to maintain columnar, as opposed to conical, bursts of air, (4) to generally improve heat and mass transfer and accelerate baking and other heat and mass transfer processes, (5) to make ovens more compact where space available for them is limited, and (6) to make oven operation quieter for a more compatible work environment. It is contemplated by the invention that different embodiments herein may be utilized in combination with one another to achieve and improve upon any of the above-stated objectives. Referring to FIG. 1, it is known in the art to pass air through long pipes 10 having a proportionately sized diameter to create a “rifling effect” of air 20 into heating chamber 30 , that is, to create more perpendicular and columnar air flow. Such systems, however, require extensively sized ovens due to the overall dimensions (sometimes exceeding 60 centimeters in length and about 1.5 or 2 centimeters in diameter) of the heating conduits/pipes 10 . According to embodiments of the invention, on the other hand, effective pipe length is substantially reduced. Referring to FIGS. 2-3, one such embodiment is depicted that is particularly, though not exclusively, useful in retrofit applications to nozzles in existing ovens. Nozzle inserts 40 are clipped, snapped, screwed, inserted, force-fit or otherwise placed in association with existing holes or nozzles 50 of an oven. The term “insert” should not be interpreted as limited to a retrofit application; use by original equipment manufacturers is contemplated as well, for example. Inserts 40 disperse and distribute heated air into plenums of an associated oven, or directly into heating chambers thereof. As shown in FIGS. 4-6, inserts 40 can be snapped into or otherwise placed in association with existing oven nozzles having a defined shape. Composite nozzle insert 40 includes a generally cylindrical outer shell 52 to which is secured insertion clip 54 . As clip 54 approaches and engages existing plenum nozzle 56 , as indicated by arrow 57 , nozzle 56 flexes clip 54 inwardly, as at 58 . As shown, nozzle 56 can be considered to be a part of the plenum plate itself. As insertion is completed, clip 54 snaps or otherwise flexes back outwardly to its original position, as at 59 in FIG. 6, to lock composite nozzle insert 40 into place. A multiplicity of much smaller conduits or tubules 60 , having a length of e.g. about 5 centimeters and a diameter of about 2 millimeters, are disposed within inserts 40 . Of course, other dimensions, such as a length of about 2 centimeters, for example, are contemplated according to the invention. Conduits 60 are together contained within a larger insert 40 , and together can create the same general pressure differential ΔP as the typical rifled nozzle of FIG. 1, but in a fraction of the length thereof. In effect, then, the multiplicity of smaller tubules or conduits 60 inserted within each nozzle comprise a compound or composite nozzle, thereby allowing for sufficient airflow to satisfy the above-mentioned and/or other objectives. According to embodiments of the invention, the ratio of pipe length to diameter is optimized to facilitate the “rifling effect” when air is directed out of the nozzle, thereby maintaining a generally columnar arrangement to generally perpendicularly strike the surface of the baked good. Use of the appropriate ratio of length to diameter is necessary to create optimal flow of air jets toward the baked product. The striking of the surface of the baked product generally perpendicularly brushes away the stagnant layer of cooler gases residing at and/or near the surface. Engagement of the impinged air at a generally perpendicular orientation with the surface of the baked product is very important for optimal increase in heating and drying effects. If a generally perpendicular orientation is not maintained, the stagnant gas is not dispersed as well. Small tubes 60 within each nozzle insert 40 are generally straight, in the previously described embodiments, and generally perpendicular to plenum plate 70 . Note airflow path 72 in the side view of FIG. 7 . In another embodiment of this invention, the small tubes may have a spiral formation, with the central axis of the spiral perpendicular to the plenum plate and/or baked product, consistent with airflow path 74 in the side view of FIG. 8 . This embodiment enables the air jets to be swirled, with the inherent advantages of improved heat and mass transfer and uniformity thereof. As shown in the top view of FIG. 9, the multiple spiral tubules of a composite nozzle insert according to this embodiment impart angular momentum to multiple air jets, providing multiple swirled airflow paths 76 . Of course, inserts 40 can be attached to one or more plenum plates within a particular oven or oven arrangement, with either the swirled or straight-line nozzle insert embodiment. Additionally, if desired, the number and/or pattern of holes or nozzles 50 , 56 receiving inserts 40 can be varied, to create desired air flow characteristics, and both straight-line and swirled inserts can be used on the same plenum or in the same oven, as may be desired. In a further embodiment, the invention contemplates the use of two or more heating pipes or ducts which have different configurations but which are of substantially the same overall length. As shown in FIG. 10, for example, one pipe represented schematically at 80 forms a generally L-shaped conduit while a second pipe represented schematically at 90 continually folds back against itself. Return air flow, illustrated schematically at 100 , 110 , is generally parallel to flow within pipes 80 , 90 . As shown, both pipes 80 , 90 have substantially the same overall length from gas propulsion mechanism 120 , such as a compressed air source, fan and/or gas propelled by the Venturi effect, to the exit of the nozzle. The pressure differential from mechanism 120 to the exit of each nozzle is the same for each of pipes 80 , 90 . In other words, if A represents mechanism 120 , B represents the end of pipe 90 , and C represents the end of pipe 80 , then P A −P B =P A −P C . Additionally, portions, e.g. generally equal portions, at the distal ends of each pipe or set of pipes, for example the last 10 centimeters or so, are arranged generally perpendicularly to the surface of the baked good to ensure the desired columnar air configuration and to achieve the desired heating effects attendant with impingement. Such an apparatus is particularly useful for new designs or redesigns of ovens. While FIG. 10 and the above description discuss the use of two pipes 80 , 90 , it should be understood that other numbers of pipes may be used to effect the desired heating, limited only by e.g. the size of the oven. Because all of the pipes are of generally the same length, the pressure drop across the pipes is substantially the same, as with the FIG. 10 embodiment. Accordingly, velocity of the impinged air exiting the nozzles is also substantially the same. Similar ducts or piping are present within the oven to facilitate return of air to the heater and the gas propulsion system. Exit orifices in the return air ducts should be spaced properly to encourage perpendicularity of air flowing out of the nozzles to the baked good. For example, use of multiple return air ducts would help to maintain pressure uniformity across the exit or return pipe orifices, as well as within the plenum. Conversely, utilization of too few return conduits or orifices would increase the pressure drop across the respective nozzles, thus affecting pressure within the plenum and causing nonuniform airflow. This nonuniformity will affect not only the return airflow out of different zones of the oven cavity, but likewise the ability of air flowing out of the nozzles into the oven cavity to strike the surface of the baked good at a perpendicular orientation and at uniform air speed, thus decreasing the desired uniformity of heat and mass transfer effects of impingement. As such, embodiments of the invention are utilized both for input and outtake of heated air to best improve heat and mass transfer efficiency on a system-wide basis. In other embodiments of the invention, oven air flow conduits leading into the processing chamber are designed to utilize air fluctuation techniques to improve heat and mass transfer and additionally to accelerate, for example, baking of a product. Such utilization of air fluctuation techniques results in a marked improvement over the continuous flow of air typically used in impingement processing chambers. Air fluctuation results in marked improvement as a result of alternately channeling air into different conduits resulting in interruptions in airflow at different locations within the processing chamber. For example, if a first conduit supplies heated or cooled air to an upper plenum and a second conduit supplies heated or cooled air to a lower plenum of the processing chamber, a valve or other shutoff mechanism is utilized to channel the entirety of airflow first into one and then into the other conduit in an alternating fashion. Such manipulation of airflow will result in discrete bursts of air coming alternately from the upper and then the lower plenum into the impingement processing chamber. The result will be improved removal of the aforementioned layers of heat and mass transfer stagnant gases at the surface of the modified product. In one embodiment, as depicted in FIG. 11, heating conduit or conduits 130 are separated to travel to top plenum 140 and base plenum 150 . As shown, air flow 160 is alternately directed completely into either top plenum 140 , as shown at 170 , or base plenum 150 , as shown at 180 , and then ultimately expressed through impinging jet holes or nozzles 190 into impingement baking or processing chamber 200 . Flap or other blocking device 210 is utilized to alternately block the respective plenums 140 , 150 . As shown herein, flap 210 oscillates up and down about pivot 215 between positions 220 and 230 , at a predetermined frequency, to optimize the improved heating. Oscillation may be caused by rotating disk 240 attached to rod or cam 250 at pivot 260 , by a solenoid, or by any other suitable means of moving the flap. Impingement is improved by airflow fluctuation caused by the illustrated mechanism. This particular embodiment is advantageous in that it can be readily adapted to many existing ovens without requiring much alteration, as flaps are presently positioned in many ovens. The existing flaps, however, are typically fixed at a given setting and are adjusted by a screw or other similar means, thereby being incapable of alternating back and forth between partially or completely closed and open positions during the heating/baking process, as hereinabove described. Maximum air velocity is increased according to this embodiment because, at two stages of each cycle, as depicted at positions 220 and 230 in FIG. 11, the entire airflow is diverted to only one of plenums 140 , 150 . Such diversion of air is typically not practiced in ovens of the prior art. It is further understood that during portions of each cycle, air is directed into both plenums 140 , 150 . Because increasing air velocity increases heating in impingement ovens, the design as depicted in FIG. 11 seeks to optimize impingement heating. Flap 210 may continually move between positions 220 and 230 or, alternatively, may be programmed to momentarily stop at respective positions 220 , 230 or at any point or points along its path of travel between positions 220 , 230 . Microprocessor or other control is contemplated. As shown in FIG. 12, a further embodiment of the invention contemplates the use of two or more channels 270 , 280 positioned in a substantially parallel and adjacent manner. With the use of solenoid 290 , or other means of effecting movement, shutter 300 having at least one opening 310 is moved across or through the channels. Shutter 300 effectively blocks airflow through the channels except when the one or more shutter openings 310 are positioned across the particular corresponding channel or channels. Utilization of shutter 300 results in fluctuation of air alternately through each channel 270 , 280 into respective top and base plenums of an oven, for example. One or more of the channels can be directed toward the top plenum, while the remaining channels can be directed toward a base plenum. Air fluctuation is effected by the constant up-and-down movement of solenoid 300 or other movement means, which continually allows air to pass into different conduits. This embodiment is particularly advantageous in that its design is compact and suitable for use over an extended period of time. Thus, according to the illustrated embodiment, air flows from source 320 , such as an oven fan or compressed air source, into pre-channel area 330 and then into channels 270 , 280 . Shutter 300 can be mounted on rollers 340 or other suitable mechanisms to permit stable and generally unhindered movement. The generally constant or other movement of shutter 300 “fires” hot air alternatively into the top or base plenum by the up-and-down movement of solenoid 290 or by operation of an alternative mechanism. In a further embodiment of the invention, depicted in FIG. 13, air fluctuation is effected by a rotating shutter disk 350 , preferably partially circular, semicircular or hemispherical in shape. Movement of shutter disk 350 is effected through any suitable means to alternately block portions of air channels 360 respectively directed toward a base plenum and a top plenum. In the illustrated embodiment, for example, air channels 360 illustrated in dashed lines are blocked by shutter disk 350 and are directed to e.g. a top plenum. Air channels 360 illustrated in solid lines are not blocked and are thus free to release impingement airflow, e.g. to a base plenum. As disk 350 rotates, as indicated by arrow 370 , the distribution of blocked and open channels changes. Air channels 360 can be of a style similar to that previously described and depicted with respect to FIG. 10, or of a different style or configuration. Hence, any of the different embodiments of the invention may be combined to optimize heating effects, heat flow and pressure equalization throughout the oven system. In a further embodiment of the invention, depicted in FIG. 14, an alternative means of effecting air fluctuation is shown. In this embodiment, shutter plate 380 , or a series of connected shutter plates, oscillate back and forth on rollers 385 above (and/or below) impingement nozzles 390 , thereby alternately blocking and opening the same to cause alternating impinging jets 393 , 396 . In one embodiment, shutter plate 380 is connected to rotating motor 400 , which oscillates shutter plate 380 . In operation, shutter plate 380 and rotating motor 400 function much like a piston in a motor. Again, due to the alternate opening and closing of air channels/nozzles 390 , heat is directed to the respective base and top plenums of the oven to optimize air velocity, air flow, and the resulting effects of heat and mass transfer. Although only a top plenum is shown in FIG. 14, it will be understood that the illustrated mechanism also can be used in association with a base plenum, alone or simultaneously with the top plenum. As shown, shutter plate 380 may have multiple openings 410 which can be configured and designed with respect to associated nozzles to allow air to flow into the desired air channels going to top and/or base plenums. In a further embodiment of the invention, depicted in FIG. 15, nozzles and return air ducts alternate their roles with the help of reciprocating pistons 420 , 430 driven by wheel 440 , itself driven by e.g. a motor, and connectors 450 . With one stroke of piston 420 , nozzles N 5 -N 8 are inlet nozzles that inject air jets 455 onto processed item 460 . Correspondingly, piston 430 moves opposite to piston 420 and removes air 465 from processing chamber 470 , via nozzles N 1 -N 4 which here function as return nozzles. With the second of a two-stroke process, the direction of movement of pistons 420 , 430 reverses. The nozzles of the first stroke become return air nozzles, and the return air ducts of the first stroke become nozzles injecting air jets into processing chamber 470 . For certain requirements, this may provide a preferred, compact embodiment of oven design and a more economic means of air jet fluctuation. Thus, drive 440 , here a wheel, raises one piston and lowers another piston simultaneously. During 180 degrees of its rotation (half of its 360 total degrees of rotation), air is expelled through jet nozzles N 5 -N 8 , and nozzles N 1 -N 4 serve as return air ducts. During the second half, or, second 180 degrees, of rotation of the wheel, N 1 -N 4 expel jets of air, and N 5 -N 8 become return air ducts. To further facilitate return airflow and reduce unnecessary strain on pistons 420 , 430 and the wheel 440 that drives them, valve V 1 opens when nozzles N 1 -N 4 release return airflow, and valve V 2 opens to help return airflow in conjunction with nozzles N 5 -N 8 . It is to be understood that FIG. 15, like other figures herein, is a simplified drawing that aims to provide an example and demonstrate a principle, and is not necessarily a blueprint for the precise mechanism that would be used according to the invention. In yet a further embodiment of the invention, shown in FIG. 16, a low-frequency whistle device 480 is placed in front of the heating fan prior to the branching of air channels 490 , 500 to respective top and base plenums 510 , 520 . As air 530 is blown across whistle device 480 , air flow fluctuation is created by low-frequency sound waves causing air vibration within plenums 510 , 520 . Air is then directed from the top and base plenums 510 , 520 into impingement baking chamber 540 at other than a continuous flow. The fluctuation caused by the low-frequency vibration of the air, represented by arrows 550 , 560 , increases and decreases pressure at the surface of the baked good in chamber 540 , thereby dispersing the stagnant gases by imploding and exploding, respectively, the stagnant layer and increasing heat and mass transfer. This embodiment as described may be used in combination with other embodiments described herein, e.g. with flap 210 previously described and shown with respect to FIG. 11, for example, to alternately direct air into respective top and base plenum portions of an oven. In further embodiments of the invention, depicted in FIGS. 17 through 21, air conduits 570 comprise perforated hollow tubes which optionally function as racks within the oven on which baked product, such as pizza 573 , is placed through door 574 . These embodiments are particularly useful in ovens where two or more racks are desired, such as in ovens containing conveyor- or batch-type systems where it is desirable to position the racks above and beneath one another, respectively, to increase the load in a given oven capacity of fixed size. Air conduit network 570 preferably includes hollow, perforated tubes, or “flutes,” and may be arranged alternately as input or impingement channels 575 with depending nozzles 580 , and return channels 585 with perforations 590 . Additionally, the use of tubing instead of plenum chambers according to embodiments of the invention encourages the use of gas pressure, providing one or more of the following advantages or other advantages: (a) more compact oven; (b) quieter oven operation; and (c) greater control because all that needs to be controlled is a pressure valve associated with e.g. a compressed gas source, not fan speed and complex airflow in large chambers. As shown in the embodiments of FIGS. 17-19, baked product 573 rests on rack 595 , which is e.g. a typical metal rack forming a grid or other pattern. According to the embodiments of FIGS. 20-21, on the other hand, product 573 rests directly on one of the gas conduits forming flute network 600 . Thus, input or impingement channel 605 according to this embodiment has both ascending and descending nozzles 610 for providing impingement jets 615 to multiple products 573 , based on airflow 620 . Return channels 622 include perforations 624 for receiving return airflow streams 626 , which ultimately combine into return airflow streams 628 . Product 573 rests directly on return channels 622 , according to this embodiment. With the embodiments of FIGS. 17-21, as well as with the other embodiments described in this application, it should be noted that the impingement and return air flutes or conduits can be formed a non-metallic substance such as silica, that not only can withstand the high temperatures of an impingement oven but also can be transparent to microwaves, radio waves, and other energy forms. Such transparency assures that the flutes or conduits will not reflect the microwave, radio wave or other energy, or otherwise render it less effective. Also with the embodiments of FIGS. 17-21, a reciprocating piston can reverse the roles of the input/impingement conduits and the return conduits, e.g. on an oscillating two-cycle basis, in a manner akin to that described with respect to FIG. 15 . Alternatively, one or more fans or compressed air sources 630 can be used to cause impingement air flow 640 and return air flow 650 , generally illustrated in FIGS. 17-19 and 21 . Embodiments of the invention enable simultaneous impingement heating of baked products on more than one rack. With previous ovens, such heating is generally considered impossible because air is directed in through a top plenum and base plenum, as previously described. If multiple racks are positioned in the oven, for example, the lower rack is shielded from the heat of the top plenum by the upper rack and vice versa. By configuring the racks to act as air conduits themselves, for example, or otherwise providing an oven as described herein, this disadvantage is overcome. As illustrated, the baked product, e.g. personal-sized pan pizza 573 , can be on a middle rack and yet impingement heating is easily effected by the fluted conduit network 570 directing impingement air from beneath and above the product. Optionally, the lower impingement flutes may be turned downward to avoid clogging of the orifices with, for example, cheese or other product toppings. In such an instance, rebound plate 670 (FIG. 19) may be positioned beneath product 573 to redirect impingement air 640 toward product 573 in a generally perpendicular orientation. According to the illustrated embodiment, return air 650 flows to an upper portion of the oven and ultimately is returned to source 630 . In a further embodiment of the invention, individual heat transfer elements 680 are affixed to each air pipe or conduit 690 in close association with jet nozzles 700 , as depicted in FIG. 22 . Heat transfer elements 680 may comprise electrical heating coils, for example. Heat transfer elements 680 may run the length of the tubing to improve heat transfer or, alternatively, may be placed inside, next to, or around a portion of the heat transfer conduit, for example, proximal the jet nozzle. In the example of FIG. 22, the same elements supply infrared heat directly to the baked product, increasing overall heat transfer. This embodiment can be used with other above-described embodiments, like that of FIG. 10, for example. Embodiments described with respect to e.g. FIGS. 10 and 17 - 22 apply impingement using tubes. This is particularly adaptable to the use of compressed air as a propellant, as referenced above, instead of e.g. large and cumbersome fans and plenum chambers. Accordingly, advantages noted above of the use of compressed air impingement can be exploited to make ovens quieter, more compact, and airflow more uniform and controlled. While the present invention has been described and illustrated with reference to particular preferred embodiments, the invention is not limited to the specific features and examples given. For example, baking, freezing or drying products other than pizzas or food items, such as drying paper, may benefit from the implementation of impingement heat and mass transfer as herein described. Although the term “air” or “airflow” is used herein, those of ordinary skill will understand that gasses other than air are equally contemplated according to embodiments of the invention. Additionally, combinations of the specified embodiments of the invention may be utilized to increase the advantages of the particular embodiments in any appropriate manner. More specifically, the embodiments shown and described with respect to any one figure can be used with and/or combined with the embodiments of any one or more additional figures. Various other modifications to the invention will occur to those of ordinary skill in the art, and other embodiments and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention.
Embodiments of the present invention can be used in situations in which heat and mass-transfer modified product, such as individual-sized pizzas, are to be prepared in relatively short periods of time, for example in one to five minutes. Through structural design features and air manipulation, embodiments of the invention provide distinct advantages over the prior art, including improving quality control by increasing uniformity of heating across the oven and within each particular product, decreasing required baking time by increasing the effectiveness of impinging air jets through air pulsation and fluctuation, and maintaining uniformity of air flow to contact the baked product substantially perpendicular to its surface. Tubes or pipes possessing impingement nozzles permit the use of compressed air instead of fans. Embodiments of the invention permit more compact oven design, better control of air jet parameters, and quieter oven operation, and other advantages.
Briefly describe the main invention outlined in the provided context.
[ "CROSS-REFERENCE TO RELATED APPLICATION The subject matter of this application is related to the subject matter of commonly assigned, co-pending Application No. 60/125,811, filed Mar. 23, 1999, priority to which is claimed under 35 U.S.C. §119(e) and which is incorporated herein by reference.", "BACKGROUND OF THE INVENTION 1.", "Field of the Invention The invention relates generally to improving airflow in heat and mass transfer processes such as baking, freezing or drying and, more particularly, to improving impingement airflow by way of air fluctuation, increased airflow uniformity, and enhanced control of airflow.", "Embodiments of the invention are particularly applicable to use with ovens designed for baking pizza, especially restaurant ovens that can utilize the limited space available more efficiently and operate more quietly for a more compatible working environment.", "Description of Related Art Impingement processing that achieves heat and mass transfer modification of products is particularly attractive because impinging jets of air disrupt the layers of stagnant gas surrounding the surface of a product, thus increasing convection heat and mass transfer.", "The latter may also be increased by: vibration and pulsation of sound waves, rifling of air jets to be more cylindrical and less conical, rotating a jet about its axis, or swirling an air jet.", "See Huang, L. et al, “Heat Transfer and Flow Visualization Experiments of Swirling, Multi-Channel, and Conventional Impinging Jets,” Int.", "J. Heat Mass Transfer , Vol. 41, No[.", "].3, pp[.", "].583-600 (1998), incorporated herein by reference, and placing a return air duct adjacent to air jet nozzles to make the jets more effective as described with respect to FIG. 1 of U.K. Patent No. 914,546, also incorporated herein by reference.", "Many impingement ovens, for example, are hampered by a lack of uniformity of airflow due to design limitations.", "Nonuniform impingement airflow can cause irregularities within the oven, within baked products and between products being cooked at the same time.", "For example, the right-hand side of a pizza may be more baked than the left-hand side in some instances of nonuniform airflow, or identical raw pizzas may be baked to differing degrees in different zones of the same oven.", "Three important types of nonuniformity that adversely affect heat and mass transfer are: (1) differences in absolute air velocity at different nozzles due to irregular air flow into and out of the plenum chambers;", "(2) discharge of air from the nozzles in a non-perpendicular orientation to the surface of the heat and mass transfer modified product;", "and (3) tendency of the air jets to fan out into a widening cone more quickly than desired.", "Past heat and mass transfer impingement devices have attempted to compensate for some of these deficiencies by passing air through long, thin, straight pipes which can impart a rifling effect to the discharged air.", "Air flowing through the pipes meets resistance to flow and experiences a pressure differential across the pipes.", "Expanding the pipe length aids in equilibrating the discharged air flowing from the pipes.", "Such processing equipment, however, tends to be very large and requires pipe lengths ranging from about 50-60 centimeters with pipe diameters of approximately two centimeters.", "Impinging jets of gas in an oven can be expelled through nozzles in pipes through which gasflows under pressure, as described in U.K. Patent No. 985,443, incorporated herein by reference.", "Also, a high velocity jet of gas, so propelled, can be used to propel the flow of other gases by applying the Venturi effect, as exemplified by Newberry, Desmond, “Vacuum Cooling,” in Proceedings of 72 nd Annual Conference of the American Society of Bakery Engineers , Chicago, Ill.", ", pp. 81-86, (March 1996), incorporated herein by reference.", "In both cases, airflow can be quieter and better controlled than with the use of plenum chambers into which air is propelled with the help of large fans and large air-circulation chambers.", "This is because the propulsion of gas under pressure can be regulated more conveniently by the adjustment of a valve opening than by the modulation of fan speed, without the inherent complexities of aerodynamic airflow within large chambers and the noise of the fan and said airflow within said chambers.", "Accordingly, an impingement system that uses compressed air in pipes with nozzles, or uses air propelled by the Venturi mechanism, promises to be quieter, more compact, and more easily controlled than circulating air with fans into plenum chambers.", "One particular shortcoming of the prior art that is addressed by embodiments of the invention is the inability to employ impingement processing more effectively in applications where it is desirable to cook a baked product, such as pizza, traveling through the oven on a conveyor belt within the limiting space constraints of a restaurant kitchen.", "Even in those instances where a conveyor belt is used, only a single rack per oven would be feasible because of the blocking that would occur between vertically spaced baked products in typical ovens.", "Examples of ovens utilizing single-layer conveyor belts for cooking can be found in Ovadia, David Z., et al.", ", “Impingement in Food Processing,” Food Technology , Vol. 52, No[.", "].4, pp. 46-50 (April 1998), incorporated herein by reference.", "SUMMARY OF THE INVENTION Embodiments of the present invention are contemplated for use in situations wherein heat and mass transfer modified product, such as individual-sized pizzas, are to be prepared in relatively short periods of time, for example in one to five minutes.", "Through e.g. structural design features and air manipulation, embodiments of the invention provide distinct advantages over the prior art, including improving quality control by increasing uniformity of heating across the oven and within each particular product, decreasing required baking time by increasing the effectiveness of impinging air jets through air pulsation and fluctuation, and maintaining uniformity of air flow to contact the baked product substantially perpendicular to its surface.", "Also, the use of tubes, or pipes possessing impingement nozzles described in the following, permits the use of compressed air instead of fans and the implementation of related advantages, permitting more compact oven design, better control of air jet parameters, and quieter oven operation, for example.", "To overcome disadvantages of the prior art, embodiments of the invention utilize multiple short, thin, straight pipes to effect a columnar airflow which strikes perpendicularly to the surface of the heat and transfer modified product.", "The pipes are configured to achieve a predetermined ratio of length to diameter and desired pressure differentials across the respective pipes.", "A multiplicity of smaller adjacent pipes is used to facilitate a compact oven, while maintaining the appropriate length-to-diameter ratio necessary for the rifling of impinging jets.", "While said smaller pipes may be straight, they may also be spiraled to create swirled jet flow.", "Alternatively, pipes of substantially equal total length are configured to effect heating wherein one or a set of the pipes are folded back upon themselves or otherwise configured to facilitate a compact-sized heat and mass transfer processing device, such as an oven.", "In another embodiment, variations in air fluctuation are effected with a shutter, flap, or other mechanism used to alternately route air through airflow conduits to different plenums or areas within the processing chamber to improve and accelerate heat and mass transfer.", "In one embodiment, a solenoid is employed to alternately open and close two channels through which air is alternately directed.", "In a further embodiment, a low-frequency whistle mechanism is placed opposite the flow of air being channeled into the processing cavity, but proximal to the plenums or other areas within the processing chamber to create low-frequency air vibration, thereby causing increased fluctuation in the airflow.", "Although embodiments of the invention are especially well-suited to preparation of individual-sized pizzas, the invention is not limited to these embodiments.", "Larger pizzas, other pizza-type and pizza-related food products, and other food and non-food products (e.g., drying paper, textiles, wood and curing electronic circuit boards, etc.) also can be prepared according to embodiments of the invention.", "More specifically, a nozzle insert according to an embodiment of the invention is for an impingement oven, the nozzle insert comprising an outer shell, connection structure, operably coupleable with the outer shell, constructed to position the nozzle insert to direct gasflow toward a processing chamber of an impingement oven, and a plurality of conduits disposed within the outer shell, the plurality of conduits being constructed to create a rifling effect on gasflow passing through the plurality of conduits, thereby creating a plurality of gas jets for impinging on a product in the processing chamber.", "The outer shell is generally cylindrical, according to one embodiment, and the plurality of conduits comprises a plurality of generally cylindrical tubes.", "The connection structure can be constructed to removably connect the nozzle insert in position within the oven.", "According to one embodiment, the outer shell has an overall length of between about 2 cm and about 5 cm, and the plurality of conduits each have a diameter of between about 0.1 and 0.2 cm.", "The nozzle insert preferably creates a pressure differential between a processing-chamber end thereof and an opposite end thereof, the pressure differential being generally the same as that created by a single conduit having a length up to about 12 times longer than the outer shell and having a diameter up to about 10 times the diameter of the plurality of conduits.", "The connection structure is constructed to removably connect the nozzle insert to a nozzle of the impingement oven, according to one embodiment, and the plurality of conduits are generally straight and provide a generally linear gasflow path.", "Alternatively, the plurality of conduits can be generally curved and provide a generally spiral gasflow path.", "Further, according to one embodiment the connection structure is constructed to connect the nozzle insert to a plenum of the impingement oven.", "According to an alternative embodiment of the invention, an impingement oven includes a processing chamber and a plurality of nozzle inserts positioned to direct gasflow to the processing chamber, each nozzle insert comprising an outer shell, connection structure, operably coupleable with the outer shell, constructed to position the nozzle insert to direct gasflow toward the processing chamber of the impingement oven, and a plurality of conduits disposed within the outer shell, the plurality of conduits being constructed to create a rifling effect on gasflow passing through the plurality of conduits, thereby creating a plurality of gas jets for impinging on a product in the processing chamber.", "According to an alternative embodiment of the invention, an impingement oven comprises a source of gas and a plurality of conduits constructed to direct heated gas from the source to a processing chamber within the oven, the plurality of conduits further being constructed to direct impinging gas to a product within the processing chamber, the plurality of conduits terminating at the processing chamber at different distances from the source;", "the plurality of conduits each having generally the same length.", "At least one of the conduits can fold back on itself between the source and the processing chamber.", "The impingement oven can further comprise a plurality of return conduits constructed to direct return gas from the processing chamber to the source, the return conduits originating at the processing chamber at different distances from the source, the return conduits each having generally the same length.", "At least one of the return conduits can fold back on itself between the processing chamber and the source.", "The impingement oven can further include at least one nozzle insert, in fluid communication with at least one of the conduits, the at least one nozzle insert being positioned to direct gasflow to the processing chamber, the at least one nozzle insert comprising, an outer shell, connection structure, operably coupleable with the outer shell, constructed to position the nozzle insert to direct gasflow toward the processing chamber of the impingement oven, and a plurality of subconduits disposed within the outer shell, the plurality of subconduits being constructed to create a rifling effect on gasflow passing through the plurality of subconduits, thereby creating a plurality of gas jets for impinging on the product within the processing chamber.", "According to an alternative embodiment, an impingement oven comprises a processing chamber, first structure at the processing chamber for directing impinging gas to a product in the processing chamber, second structure at the processing chamber for directing impinging gas to the product in the processing chamber, a gas source in fluid communication with the first and second structures, conduits for directing gas from the gas source to the first structure and the second structure and a gas fluctuation device, operably coupled with the conduits, for alternately channeling gas either to the first structure or to the second structure.", "The first structure can comprise a plurality of nozzles of the impingement oven, and the plurality of nozzles can be a plurality of first nozzles.", "The second structure can comprise a plurality of second nozzles of the impingement oven, wherein the second nozzles are disposed on an opposite side of the processing chamber from the first nozzles.", "The first structure comprises a plenum plate of the impingement oven, according to one embodiment, and the second structure comprises the plenum plate or an additional plenum plate of the impingement oven.", "The first structure can comprise a plurality of first nozzles and the second structure a plurality of second nozzles, the first nozzles being interspersed with the second nozzles.", "The first and/or second structure comprises at least one nozzle insert, according to one embodiment, in fluid communication with at least one of the conduits, the at least one nozzle insert being positioned to direct gasflow to the processing chamber, the at least one nozzle insert comprising an outer shell, connection structure, operably coupleable with the outer shell, constructed to position the nozzle insert to direct gasflow toward the processing chamber of the impingement oven, and a plurality of subconduits disposed within the outer shell, the plurality of subconduits being constructed to create a rifling effect on gasflow passing through the plurality of subconduits, thereby creating a plurality of gas jets for impinging on the product within the processing chamber.", "The gas source can comprise a source of compressed air, and the gas fluctuation device can comprise a shutter, the shutter moving to a first position to direct gas to the first structure and moving to a second position to direct gas to the second structure.", "The shutter can comprise a pivoted flap, and can define at least one aperture therethrough for allowing gas to flow alternately to the first structure and the second structure.", "The shutter can define a generally circular shape and define a plurality of apertures disposed therethrough, and the oven further can comprise a shutter plate operably connected to the shutter, rotation of the shutter plate with respect to the shutter allowing gas to flow through the apertures alternately to the first structure and the second structure.", "The shutter is constructed for linear movement between the first and second positions, according to one embodiment.", "The gas fluctuation device also can comprise at least one reciprocating piston in fluid communication with at least one of the conduits.", "The conduits can comprise a first conduit in fluid communication with the first structure and a second conduit in fluid communication with the second structure, and the gas fluctuation device can comprise a first reciprocating piston in fluid communication with the first conduit, and a second reciprocating piston in fluid communication with the second conduit.", "The first and second structure can comprise a plurality of nozzles.", "The oven further can comprise a plurality of valves, in fluid communication with the first and second conduits, for aiding the gas fluctuation device.", "The conduits comprise at least one first conduit constructed to direct gas from the source toward the processing chamber, according to one embodiment, and at least one second conduit constructed to direct gas from the processing chamber toward the source.", "The gas fluctuation device reverses gasflow within the oven such that the first conduit also directs gas from the processing chamber toward the source and such that the second conduit also directs gas from the source toward the processing chamber.", "The conduits terminate at the processing chamber at different distances from the source, according to one embodiment;", "the plurality of conduits each having generally the same length.", "Additionally, structure for producing low-frequency vibration also can be provided.", "According to another embodiment of the invention, an impingement oven comprises a processing chamber, first means at the processing chamber for directing impinging gas to a product in the processing chamber, second means at the processing chamber for directing impinging gas to the product in the processing chamber, means for providing a source of gas, means for directing gas from the means for providing to the first means and the second means, and means for alternately channeling gas either to the first means or to the second means.", "According to another embodiment of the invention, an impingement oven comprises a processing chamber, a gas source, an input channel for directing gas from the source toward the processing chamber, and a return channel for directing gas from the processing chamber toward the source, wherein at least one of the input channel and the output channel are constructed to support a product to be processed by the oven in the processing chamber.", "The processing chamber is constructed to accommodate multiple products top-to-bottom within the processing chamber, according to one embodiment, and the oven further comprises multiple input channels disposed directly above and directly below each product within the processing chamber.", "The product can be supported on the output channel.", "The oven further can comprise structure to reverse the flow of gas in the input channel and the output channel, such that the input channel directs gas from the processing chamber toward the source and the return channel directs gas from the source toward the processing chamber.", "The gas source can comprise a compressed gas source, and the structure to reverse can comprise at least one valve associated with the compressed gas source.", "According to another embodiment of the invention, an impingement oven comprises a processing chamber for accommodating a product to be processed by the oven, a gas source, an input channel for directing gas from the source toward the processing chamber, and a return channel for directing gas from the processing chamber toward the source, the input channel and the return channel comprising tubes disposed within the processing chamber in direct association with the product.", "The oven can comprise structure to reverse the flow of gas in the input channel and the output channel, such that the input channel directs gas from the processing chamber toward the source and the return channel directs gas from the source toward the processing chamber.", "The input channel can comprise at least one nozzle aimed toward the product for directing gas toward the product, and the return channel can comprise at least one aperture aimed away from the product for receiving return air from the processing chamber.", "Both the input channel and the return channel are disposed above the product, according to one embodiment, and the input channel can be disposed below the product and comprise at least one nozzle aimed away from the product.", "A second input channel can be disposed above the product, the second input channel comprising at least one nozzle aimed toward the product.", "A rebound plate for receiving and reflecting gas received from the at least one nozzle can also be provided.", "The gas source can be a compressed gas source.", "The input channel can comprise at least one nozzle, and the oven further can comprise a heating element disposed around the at least one nozzle for improving heat transfer within the oven.", "The heating element can comprise an electric coil or an infrared heating element, for example.", "The oven can comprise two input channels disposed within the processing chamber for directing gas toward the product at different distances from the source, and the two input channels can each have generally the same length.", "One of the input channels folds back upon itself, according to one embodiment, and at least one of the input channel and the return channel contacts the product.", "Other features and advantages of the invention will be apparent from the following description and claims.", "BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will be described with respect to the figures, in which like reference numerals denote like elements, and in which: FIG. 1 shows a typical rifled nozzle.", "FIGS. 2-3 show an embodiment of the invention utilizing a pipe configuration to improve impingement airflow.", "FIGS. 4-6 show insertion of the FIG. 2 embodiment into an existing nozzle according to an embodiment of the invention.", "FIG. 7 shows an airflow path according to the FIG. 2 embodiment.", "FIGS. 8-9 show airflow paths according to an alternative embodiment.", "FIG. 10 shows an embodiment of the invention utilizing an alternative pipe configuration to improve impingement airflow.", "FIG. 11 shows an embodiment of the invention utilizing air fluctuation to improve baking characteristics.", "FIG. 12 shows an alternative embodiment of the invention utilizing air fluctuation to improve baking characteristics.", "FIG. 13 shows an alternative embodiment of the invention utilizing air fluctuation to improve baking characteristics.", "FIG. 14 shows an alternative embodiment of the invention utilizing air fluctuation to improve baking characteristics.", "FIG. 15 shows an embodiment of the invention utilizing air fluctuation to improve baking characteristics.", "FIG. 16 shows an embodiment of the invention using low-frequency sound waves to cause air fluctuation.", "FIG. 17 shows an embodiment of the invention utilizing baking racks and impingement heating.", "FIG. 18 is a side view of the embodiment depicted in FIG. 17 .", "FIG. 19 is a view of the embodiment depicted in FIG. 17, utilizing an alternative method of redirecting impingement airflow.", "FIGS. 20-21 are side and end views, respectively, of an embodiment of the invention utilizing baking racks to effect impingement heating.", "FIG. 22 is a view of an embodiment of the invention depicting individual heating elements in association with heating conduits.", "DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Embodiments of the invention provide devices and methods for improving impingement airflow in baking ovens by manipulation of the design and/or structure of heating conduits, piping and/or air nozzles, and/or or by utilization of air fluctuation techniques and designs.", "Embodiments of the invention are designed: (1) to equalize air speed from different nozzles into and out of the plenums or other chambers of an oven, (2) to ensure the maintenance of a substantially perpendicular orientation between the propelled jets of air from the nozzles and the surface of the baked good being heated, (3) to maintain columnar, as opposed to conical, bursts of air, (4) to generally improve heat and mass transfer and accelerate baking and other heat and mass transfer processes, (5) to make ovens more compact where space available for them is limited, and (6) to make oven operation quieter for a more compatible work environment.", "It is contemplated by the invention that different embodiments herein may be utilized in combination with one another to achieve and improve upon any of the above-stated objectives.", "Referring to FIG. 1, it is known in the art to pass air through long pipes 10 having a proportionately sized diameter to create a “rifling effect”", "of air 20 into heating chamber 30 , that is, to create more perpendicular and columnar air flow.", "Such systems, however, require extensively sized ovens due to the overall dimensions (sometimes exceeding 60 centimeters in length and about 1.5 or 2 centimeters in diameter) of the heating conduits/pipes 10 .", "According to embodiments of the invention, on the other hand, effective pipe length is substantially reduced.", "Referring to FIGS. 2-3, one such embodiment is depicted that is particularly, though not exclusively, useful in retrofit applications to nozzles in existing ovens.", "Nozzle inserts 40 are clipped, snapped, screwed, inserted, force-fit or otherwise placed in association with existing holes or nozzles 50 of an oven.", "The term “insert”", "should not be interpreted as limited to a retrofit application;", "use by original equipment manufacturers is contemplated as well, for example.", "Inserts 40 disperse and distribute heated air into plenums of an associated oven, or directly into heating chambers thereof.", "As shown in FIGS. 4-6, inserts 40 can be snapped into or otherwise placed in association with existing oven nozzles having a defined shape.", "Composite nozzle insert 40 includes a generally cylindrical outer shell 52 to which is secured insertion clip 54 .", "As clip 54 approaches and engages existing plenum nozzle 56 , as indicated by arrow 57 , nozzle 56 flexes clip 54 inwardly, as at 58 .", "As shown, nozzle 56 can be considered to be a part of the plenum plate itself.", "As insertion is completed, clip 54 snaps or otherwise flexes back outwardly to its original position, as at 59 in FIG. 6, to lock composite nozzle insert 40 into place.", "A multiplicity of much smaller conduits or tubules 60 , having a length of e.g. about 5 centimeters and a diameter of about 2 millimeters, are disposed within inserts 40 .", "Of course, other dimensions, such as a length of about 2 centimeters, for example, are contemplated according to the invention.", "Conduits 60 are together contained within a larger insert 40 , and together can create the same general pressure differential ΔP as the typical rifled nozzle of FIG. 1, but in a fraction of the length thereof.", "In effect, then, the multiplicity of smaller tubules or conduits 60 inserted within each nozzle comprise a compound or composite nozzle, thereby allowing for sufficient airflow to satisfy the above-mentioned and/or other objectives.", "According to embodiments of the invention, the ratio of pipe length to diameter is optimized to facilitate the “rifling effect”", "when air is directed out of the nozzle, thereby maintaining a generally columnar arrangement to generally perpendicularly strike the surface of the baked good.", "Use of the appropriate ratio of length to diameter is necessary to create optimal flow of air jets toward the baked product.", "The striking of the surface of the baked product generally perpendicularly brushes away the stagnant layer of cooler gases residing at and/or near the surface.", "Engagement of the impinged air at a generally perpendicular orientation with the surface of the baked product is very important for optimal increase in heating and drying effects.", "If a generally perpendicular orientation is not maintained, the stagnant gas is not dispersed as well.", "Small tubes 60 within each nozzle insert 40 are generally straight, in the previously described embodiments, and generally perpendicular to plenum plate 70 .", "Note airflow path 72 in the side view of FIG. 7 .", "In another embodiment of this invention, the small tubes may have a spiral formation, with the central axis of the spiral perpendicular to the plenum plate and/or baked product, consistent with airflow path 74 in the side view of FIG. 8 .", "This embodiment enables the air jets to be swirled, with the inherent advantages of improved heat and mass transfer and uniformity thereof.", "As shown in the top view of FIG. 9, the multiple spiral tubules of a composite nozzle insert according to this embodiment impart angular momentum to multiple air jets, providing multiple swirled airflow paths 76 .", "Of course, inserts 40 can be attached to one or more plenum plates within a particular oven or oven arrangement, with either the swirled or straight-line nozzle insert embodiment.", "Additionally, if desired, the number and/or pattern of holes or nozzles 50 , 56 receiving inserts 40 can be varied, to create desired air flow characteristics, and both straight-line and swirled inserts can be used on the same plenum or in the same oven, as may be desired.", "In a further embodiment, the invention contemplates the use of two or more heating pipes or ducts which have different configurations but which are of substantially the same overall length.", "As shown in FIG. 10, for example, one pipe represented schematically at 80 forms a generally L-shaped conduit while a second pipe represented schematically at 90 continually folds back against itself.", "Return air flow, illustrated schematically at 100 , 110 , is generally parallel to flow within pipes 80 , 90 .", "As shown, both pipes 80 , 90 have substantially the same overall length from gas propulsion mechanism 120 , such as a compressed air source, fan and/or gas propelled by the Venturi effect, to the exit of the nozzle.", "The pressure differential from mechanism 120 to the exit of each nozzle is the same for each of pipes 80 , 90 .", "In other words, if A represents mechanism 120 , B represents the end of pipe 90 , and C represents the end of pipe 80 , then P A −P B =P A −P C .", "Additionally, portions, e.g. generally equal portions, at the distal ends of each pipe or set of pipes, for example the last 10 centimeters or so, are arranged generally perpendicularly to the surface of the baked good to ensure the desired columnar air configuration and to achieve the desired heating effects attendant with impingement.", "Such an apparatus is particularly useful for new designs or redesigns of ovens.", "While FIG. 10 and the above description discuss the use of two pipes 80 , 90 , it should be understood that other numbers of pipes may be used to effect the desired heating, limited only by e.g. the size of the oven.", "Because all of the pipes are of generally the same length, the pressure drop across the pipes is substantially the same, as with the FIG. 10 embodiment.", "Accordingly, velocity of the impinged air exiting the nozzles is also substantially the same.", "Similar ducts or piping are present within the oven to facilitate return of air to the heater and the gas propulsion system.", "Exit orifices in the return air ducts should be spaced properly to encourage perpendicularity of air flowing out of the nozzles to the baked good.", "For example, use of multiple return air ducts would help to maintain pressure uniformity across the exit or return pipe orifices, as well as within the plenum.", "Conversely, utilization of too few return conduits or orifices would increase the pressure drop across the respective nozzles, thus affecting pressure within the plenum and causing nonuniform airflow.", "This nonuniformity will affect not only the return airflow out of different zones of the oven cavity, but likewise the ability of air flowing out of the nozzles into the oven cavity to strike the surface of the baked good at a perpendicular orientation and at uniform air speed, thus decreasing the desired uniformity of heat and mass transfer effects of impingement.", "As such, embodiments of the invention are utilized both for input and outtake of heated air to best improve heat and mass transfer efficiency on a system-wide basis.", "In other embodiments of the invention, oven air flow conduits leading into the processing chamber are designed to utilize air fluctuation techniques to improve heat and mass transfer and additionally to accelerate, for example, baking of a product.", "Such utilization of air fluctuation techniques results in a marked improvement over the continuous flow of air typically used in impingement processing chambers.", "Air fluctuation results in marked improvement as a result of alternately channeling air into different conduits resulting in interruptions in airflow at different locations within the processing chamber.", "For example, if a first conduit supplies heated or cooled air to an upper plenum and a second conduit supplies heated or cooled air to a lower plenum of the processing chamber, a valve or other shutoff mechanism is utilized to channel the entirety of airflow first into one and then into the other conduit in an alternating fashion.", "Such manipulation of airflow will result in discrete bursts of air coming alternately from the upper and then the lower plenum into the impingement processing chamber.", "The result will be improved removal of the aforementioned layers of heat and mass transfer stagnant gases at the surface of the modified product.", "In one embodiment, as depicted in FIG. 11, heating conduit or conduits 130 are separated to travel to top plenum 140 and base plenum 150 .", "As shown, air flow 160 is alternately directed completely into either top plenum 140 , as shown at 170 , or base plenum 150 , as shown at 180 , and then ultimately expressed through impinging jet holes or nozzles 190 into impingement baking or processing chamber 200 .", "Flap or other blocking device 210 is utilized to alternately block the respective plenums 140 , 150 .", "As shown herein, flap 210 oscillates up and down about pivot 215 between positions 220 and 230 , at a predetermined frequency, to optimize the improved heating.", "Oscillation may be caused by rotating disk 240 attached to rod or cam 250 at pivot 260 , by a solenoid, or by any other suitable means of moving the flap.", "Impingement is improved by airflow fluctuation caused by the illustrated mechanism.", "This particular embodiment is advantageous in that it can be readily adapted to many existing ovens without requiring much alteration, as flaps are presently positioned in many ovens.", "The existing flaps, however, are typically fixed at a given setting and are adjusted by a screw or other similar means, thereby being incapable of alternating back and forth between partially or completely closed and open positions during the heating/baking process, as hereinabove described.", "Maximum air velocity is increased according to this embodiment because, at two stages of each cycle, as depicted at positions 220 and 230 in FIG. 11, the entire airflow is diverted to only one of plenums 140 , 150 .", "Such diversion of air is typically not practiced in ovens of the prior art.", "It is further understood that during portions of each cycle, air is directed into both plenums 140 , 150 .", "Because increasing air velocity increases heating in impingement ovens, the design as depicted in FIG. 11 seeks to optimize impingement heating.", "Flap 210 may continually move between positions 220 and 230 or, alternatively, may be programmed to momentarily stop at respective positions 220 , 230 or at any point or points along its path of travel between positions 220 , 230 .", "Microprocessor or other control is contemplated.", "As shown in FIG. 12, a further embodiment of the invention contemplates the use of two or more channels 270 , 280 positioned in a substantially parallel and adjacent manner.", "With the use of solenoid 290 , or other means of effecting movement, shutter 300 having at least one opening 310 is moved across or through the channels.", "Shutter 300 effectively blocks airflow through the channels except when the one or more shutter openings 310 are positioned across the particular corresponding channel or channels.", "Utilization of shutter 300 results in fluctuation of air alternately through each channel 270 , 280 into respective top and base plenums of an oven, for example.", "One or more of the channels can be directed toward the top plenum, while the remaining channels can be directed toward a base plenum.", "Air fluctuation is effected by the constant up-and-down movement of solenoid 300 or other movement means, which continually allows air to pass into different conduits.", "This embodiment is particularly advantageous in that its design is compact and suitable for use over an extended period of time.", "Thus, according to the illustrated embodiment, air flows from source 320 , such as an oven fan or compressed air source, into pre-channel area 330 and then into channels 270 , 280 .", "Shutter 300 can be mounted on rollers 340 or other suitable mechanisms to permit stable and generally unhindered movement.", "The generally constant or other movement of shutter 300 “fires”", "hot air alternatively into the top or base plenum by the up-and-down movement of solenoid 290 or by operation of an alternative mechanism.", "In a further embodiment of the invention, depicted in FIG. 13, air fluctuation is effected by a rotating shutter disk 350 , preferably partially circular, semicircular or hemispherical in shape.", "Movement of shutter disk 350 is effected through any suitable means to alternately block portions of air channels 360 respectively directed toward a base plenum and a top plenum.", "In the illustrated embodiment, for example, air channels 360 illustrated in dashed lines are blocked by shutter disk 350 and are directed to e.g. a top plenum.", "Air channels 360 illustrated in solid lines are not blocked and are thus free to release impingement airflow, e.g. to a base plenum.", "As disk 350 rotates, as indicated by arrow 370 , the distribution of blocked and open channels changes.", "Air channels 360 can be of a style similar to that previously described and depicted with respect to FIG. 10, or of a different style or configuration.", "Hence, any of the different embodiments of the invention may be combined to optimize heating effects, heat flow and pressure equalization throughout the oven system.", "In a further embodiment of the invention, depicted in FIG. 14, an alternative means of effecting air fluctuation is shown.", "In this embodiment, shutter plate 380 , or a series of connected shutter plates, oscillate back and forth on rollers 385 above (and/or below) impingement nozzles 390 , thereby alternately blocking and opening the same to cause alternating impinging jets 393 , 396 .", "In one embodiment, shutter plate 380 is connected to rotating motor 400 , which oscillates shutter plate 380 .", "In operation, shutter plate 380 and rotating motor 400 function much like a piston in a motor.", "Again, due to the alternate opening and closing of air channels/nozzles 390 , heat is directed to the respective base and top plenums of the oven to optimize air velocity, air flow, and the resulting effects of heat and mass transfer.", "Although only a top plenum is shown in FIG. 14, it will be understood that the illustrated mechanism also can be used in association with a base plenum, alone or simultaneously with the top plenum.", "As shown, shutter plate 380 may have multiple openings 410 which can be configured and designed with respect to associated nozzles to allow air to flow into the desired air channels going to top and/or base plenums.", "In a further embodiment of the invention, depicted in FIG. 15, nozzles and return air ducts alternate their roles with the help of reciprocating pistons 420 , 430 driven by wheel 440 , itself driven by e.g. a motor, and connectors 450 .", "With one stroke of piston 420 , nozzles N 5 -N 8 are inlet nozzles that inject air jets 455 onto processed item 460 .", "Correspondingly, piston 430 moves opposite to piston 420 and removes air 465 from processing chamber 470 , via nozzles N 1 -N 4 which here function as return nozzles.", "With the second of a two-stroke process, the direction of movement of pistons 420 , 430 reverses.", "The nozzles of the first stroke become return air nozzles, and the return air ducts of the first stroke become nozzles injecting air jets into processing chamber 470 .", "For certain requirements, this may provide a preferred, compact embodiment of oven design and a more economic means of air jet fluctuation.", "Thus, drive 440 , here a wheel, raises one piston and lowers another piston simultaneously.", "During 180 degrees of its rotation (half of its 360 total degrees of rotation), air is expelled through jet nozzles N 5 -N 8 , and nozzles N 1 -N 4 serve as return air ducts.", "During the second half, or, second 180 degrees, of rotation of the wheel, N 1 -N 4 expel jets of air, and N 5 -N 8 become return air ducts.", "To further facilitate return airflow and reduce unnecessary strain on pistons 420 , 430 and the wheel 440 that drives them, valve V 1 opens when nozzles N 1 -N 4 release return airflow, and valve V 2 opens to help return airflow in conjunction with nozzles N 5 -N 8 .", "It is to be understood that FIG. 15, like other figures herein, is a simplified drawing that aims to provide an example and demonstrate a principle, and is not necessarily a blueprint for the precise mechanism that would be used according to the invention.", "In yet a further embodiment of the invention, shown in FIG. 16, a low-frequency whistle device 480 is placed in front of the heating fan prior to the branching of air channels 490 , 500 to respective top and base plenums 510 , 520 .", "As air 530 is blown across whistle device 480 , air flow fluctuation is created by low-frequency sound waves causing air vibration within plenums 510 , 520 .", "Air is then directed from the top and base plenums 510 , 520 into impingement baking chamber 540 at other than a continuous flow.", "The fluctuation caused by the low-frequency vibration of the air, represented by arrows 550 , 560 , increases and decreases pressure at the surface of the baked good in chamber 540 , thereby dispersing the stagnant gases by imploding and exploding, respectively, the stagnant layer and increasing heat and mass transfer.", "This embodiment as described may be used in combination with other embodiments described herein, e.g. with flap 210 previously described and shown with respect to FIG. 11, for example, to alternately direct air into respective top and base plenum portions of an oven.", "In further embodiments of the invention, depicted in FIGS. 17 through 21, air conduits 570 comprise perforated hollow tubes which optionally function as racks within the oven on which baked product, such as pizza 573 , is placed through door 574 .", "These embodiments are particularly useful in ovens where two or more racks are desired, such as in ovens containing conveyor- or batch-type systems where it is desirable to position the racks above and beneath one another, respectively, to increase the load in a given oven capacity of fixed size.", "Air conduit network 570 preferably includes hollow, perforated tubes, or “flutes,” and may be arranged alternately as input or impingement channels 575 with depending nozzles 580 , and return channels 585 with perforations 590 .", "Additionally, the use of tubing instead of plenum chambers according to embodiments of the invention encourages the use of gas pressure, providing one or more of the following advantages or other advantages: (a) more compact oven;", "(b) quieter oven operation;", "and (c) greater control because all that needs to be controlled is a pressure valve associated with e.g. a compressed gas source, not fan speed and complex airflow in large chambers.", "As shown in the embodiments of FIGS. 17-19, baked product 573 rests on rack 595 , which is e.g. a typical metal rack forming a grid or other pattern.", "According to the embodiments of FIGS. 20-21, on the other hand, product 573 rests directly on one of the gas conduits forming flute network 600 .", "Thus, input or impingement channel 605 according to this embodiment has both ascending and descending nozzles 610 for providing impingement jets 615 to multiple products 573 , based on airflow 620 .", "Return channels 622 include perforations 624 for receiving return airflow streams 626 , which ultimately combine into return airflow streams 628 .", "Product 573 rests directly on return channels 622 , according to this embodiment.", "With the embodiments of FIGS. 17-21, as well as with the other embodiments described in this application, it should be noted that the impingement and return air flutes or conduits can be formed a non-metallic substance such as silica, that not only can withstand the high temperatures of an impingement oven but also can be transparent to microwaves, radio waves, and other energy forms.", "Such transparency assures that the flutes or conduits will not reflect the microwave, radio wave or other energy, or otherwise render it less effective.", "Also with the embodiments of FIGS. 17-21, a reciprocating piston can reverse the roles of the input/impingement conduits and the return conduits, e.g. on an oscillating two-cycle basis, in a manner akin to that described with respect to FIG. 15 .", "Alternatively, one or more fans or compressed air sources 630 can be used to cause impingement air flow 640 and return air flow 650 , generally illustrated in FIGS. 17-19 and 21 .", "Embodiments of the invention enable simultaneous impingement heating of baked products on more than one rack.", "With previous ovens, such heating is generally considered impossible because air is directed in through a top plenum and base plenum, as previously described.", "If multiple racks are positioned in the oven, for example, the lower rack is shielded from the heat of the top plenum by the upper rack and vice versa.", "By configuring the racks to act as air conduits themselves, for example, or otherwise providing an oven as described herein, this disadvantage is overcome.", "As illustrated, the baked product, e.g. personal-sized pan pizza 573 , can be on a middle rack and yet impingement heating is easily effected by the fluted conduit network 570 directing impingement air from beneath and above the product.", "Optionally, the lower impingement flutes may be turned downward to avoid clogging of the orifices with, for example, cheese or other product toppings.", "In such an instance, rebound plate 670 (FIG.", "19) may be positioned beneath product 573 to redirect impingement air 640 toward product 573 in a generally perpendicular orientation.", "According to the illustrated embodiment, return air 650 flows to an upper portion of the oven and ultimately is returned to source 630 .", "In a further embodiment of the invention, individual heat transfer elements 680 are affixed to each air pipe or conduit 690 in close association with jet nozzles 700 , as depicted in FIG. 22 .", "Heat transfer elements 680 may comprise electrical heating coils, for example.", "Heat transfer elements 680 may run the length of the tubing to improve heat transfer or, alternatively, may be placed inside, next to, or around a portion of the heat transfer conduit, for example, proximal the jet nozzle.", "In the example of FIG. 22, the same elements supply infrared heat directly to the baked product, increasing overall heat transfer.", "This embodiment can be used with other above-described embodiments, like that of FIG. 10, for example.", "Embodiments described with respect to e.g. FIGS. 10 and 17 - 22 apply impingement using tubes.", "This is particularly adaptable to the use of compressed air as a propellant, as referenced above, instead of e.g. large and cumbersome fans and plenum chambers.", "Accordingly, advantages noted above of the use of compressed air impingement can be exploited to make ovens quieter, more compact, and airflow more uniform and controlled.", "While the present invention has been described and illustrated with reference to particular preferred embodiments, the invention is not limited to the specific features and examples given.", "For example, baking, freezing or drying products other than pizzas or food items, such as drying paper, may benefit from the implementation of impingement heat and mass transfer as herein described.", "Although the term “air”", "or “airflow”", "is used herein, those of ordinary skill will understand that gasses other than air are equally contemplated according to embodiments of the invention.", "Additionally, combinations of the specified embodiments of the invention may be utilized to increase the advantages of the particular embodiments in any appropriate manner.", "More specifically, the embodiments shown and described with respect to any one figure can be used with and/or combined with the embodiments of any one or more additional figures.", "Various other modifications to the invention will occur to those of ordinary skill in the art, and other embodiments and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention." ]
This application claims priority under 35 U.S.C. § 119 to Application No. 2003-151214, filed in Japan on May 28, 2003; the entire content of which is hereby incorporated by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of maintaining or improving the activity of industrially useful nitrile hydratase. The activity referred to herein is a nitrile hydrating activity determined by a method described in the Examples. 2. Description of the Related Art The nitrile hydrating activity of nitrile hydratase is unstable and easily reduced with time. For preventing such reduction in the nitrile hydrating activity of nitrile hydratase with time to maintain the activity, a method which comprises adding at least one compound selected from a nitrile, an amide, an organic acid and a salt thereof as a stabilizer to a suspension or solution of a nitrile hydratase-containing microorganism or a treated material of the microorganism is disclosed (see, for example, JP-B 5-43351 and JP-B 4-48435). A storage method wherein a microorganism or a treated microbial material is in a state suspended in an aqueous medium and the aqueous medium is neutral or weakly basic and having dissolved therein an inorganic salt at a concentration of 100 mM to its saturated concentration is also disclosed (see, for example, JP-A 8-112089). However, both the methods are effective only in maintaining a nitrile hydratase activity, and an effect of further increasing the nitrile hydratase activity is not reported therein. As a method of increasing a nitrile hydrating activity by producing a nitrile hydratase-containing microorganism through culture and then subjecting the resulting microorganism or a treated material of the microorganism to some treatment, a method which comprises irradiating the resulting Gram-positive microorganism having a nitrile hydratase activity with light is disclosed (see, for example, JP-B2-35). However, this method is effective only in increasing the nitrile hydratase activity of the microorganism obtained through culture, and does not improve the nitrile hydratase activity of a microorganism whose activity was reduced. In addition, this method is irrelevant to maintenance of nitrile hydratase activity. It is also reported that oxygen is necessary for culturing a nitrile hydratase-containing microorganism, and the concentration of dissolved oxygen during culture is maintained in the range of from 1 ppm to its saturated concentration, whereby the growth of the microorganism can be improved, and simultaneously the microorganism expressing a nitrile hydratase activity at high levels can be obtained (see, for example, JP-A 2002-17339). However, it is merely reported in this method that during culture, that is, under conditions where the nitrile hydratase-containing microorganism grows, there is the optimum concentration of dissolved oxygen in a culture solution in order to express a nitrile hydratase activity, and there is no description therein of maintenance and improvement of the nitrile hydratase activity under conditions where the nitrile hydratase-containing microorganism does not grow, that is, after the conclusion of culture. The detailed mechanism of expression and reduction of nitrile hydratase activity is not completely elucidated, but it is described that for example, the reduction of the nitrile hydrating activity of iron-type nitrile hydratase derived from Rhodococcus sp. N-771 is attributable to oxidation, with oxygen in the air, of cysteinesulfenic acid coordinated with non-heme iron (III) as central metal into cysteinesulfinic acid (see, for example, M. Okada, M. Tsujimura and I. Endo: RIKEN Review, No. 41, p. 58-60 (2001)). It is also described that for example, the activity of iron-type nitrile hydratase derived from Rhodococcus sp. N-771 is lost when trivalent iron as central metal is reduced to divalent iron by 2-cyano-2-propylhydroxy peroxide while cysteinesulfenic acid is oxidized into cysteinesulfinic acid (see, for example, M. Okada, M. Tsujimura and I. Endo: New Development of Reaction in Organic Chemistry (in Japanese), No. 3, p. 17-20 (2001). It is also described that the structure of nitrile hydratase with cobalt as central metal, derived from Rhodococcus rhodochrous J1, is not determined, but is estimated to be similar to that of iron nitrile hydratase (see, for example, P. K. Mascharak, Coordination Chemistry Reviews, No. 225, p. 201-214 (2002)). SUMMARY OF THE INVENTION The object of the present invention is to provide a method which not only maintains the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell under conditions where the cell does not grow, but also improves the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell whose activity was once reduced. The present inventors made extensive study to solve the problem, and as a result, we found that the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell can be maintained by bringing it into contact with an oxidizing agent under conditions where the cell does not grow, and further the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell whose activity was once reduced can be improved by bringing it into contact with an oxidizing agent before or during reaction, and the present invention was thereby arrived at. That is, the present invention provides: (1) A method of maintaining or improving a nitrile hydratase activity, which comprises bringing a nitrile hydratase-containing cell or a treated material of the cell into contact with an oxidizing agent under conditions where the cell does not grow. (2) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the oxidizing agent is an oxidizing agent having a standard electrode potential in the range of 0.1 to 2.1 V relative to a standard hydrogen electrode. (3) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the oxidizing agent is at least one member selected from the group consisting of oxygen, hydrogen peroxide, potassium ferricyanide and ammonium persulfate. (4) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (3), wherein the oxygen as the oxidizing agent is supplied as an oxygen-containing gas. (5) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the concentration of the oxidizing agent is in the range of 1 ppm by weight to 10% by weight. (6) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the temperature in contact with the oxidizing agent is in the range of 0 to 60° C. (7) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the pH value in contact with the oxidizing agent is in the range of 5 to 10. (8) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the nitrile hydratase is a nitrile hydratase containing cobalt in its molecule. (9) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein a cell where the nitrile hydratase containing cobalt in its molecule is expressed by genetic recombination, or a treated material of the cell, is brought into contact with the oxidizing agent under conditions where the cell does not grow. (10) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the cell is a nitrile hydratase-containing microorganism or a treated material of the microorganism. (11) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (10), wherein the microorganism is a genetically engineered microorganism. (12) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (11), wherein the genetically engineered microorganism is genetically engineered Escherichia coli. (13) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (12), wherein a host of the genetically engineered Escherichia coli is W3110 strain (ATCC27325), HB101 strain (ATCC33694), JM109 strain (ATCC53223) or WA802 strain (ATCC33526), each of which is derived from Escherichia coli K-12. (14) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the nitrile hydratase-containing cell or a treated material of the cell is used for producing an amide compound from a nitrile compound. (15) A method of producing an amide compound from a nitrile compound, which comprises contacting a nitrile compound with the nitrile hydratase-containing cell or a treated material of the cell obtained by the method described in any one of the above-mentioned (1) to (14). DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention is described in more detail. The nitrile hydratase referred to in the present invention is an enzyme having an ability to hydrate a nitrile group of a nitrile compound to form the corresponding amide compound. The cell referred to in the present invention may be any one of microorganisms, plant cells and animal cells. The nitrile hydratase-containing microorganism is not particularly limited insofar as it is a microorganism having an ability to hydrate a nitrile group of a nitrile compound to form the corresponding amide compound. Examples thereof include Pseudonocardia thermophila JCM3095 , Achromobacter xerosis IFO12668 and Rhodococcus rhodochrous J1. The present invention also encompasses a transformant wherein a nitrile hydratase gene cloned from the above microorganism is expressed in an arbitrary host. The arbitrary host includes Escherichia coli , microorganisms of the genus Bacillus , such as Bacillus subtilis , yeasts, Actinomyces , and filamentous fungi. The host of genetically engineered Escherichia coli includes, for example, W3110 strain (ATCC27325), HB101 strain (ATCC33694), JM109 strain (ATCC53223) and WA802 strain (ATCC33526), each of which is derived from Escherichia coli K-12. Concrete examples thereof include MT-10822 (which was deposited as FERM BP-5785 on Feb. 7, 1996 with the National Institute of Bioscience and Human-Technology (Higashi 1-1-3, Tsukuba City, Ibaraki Pref., JP), the Agency of Industrial Science and Technology, the Ministry of International Trade and Industry, Japan, under the Budapest Treaty on international approval of microbial deposition in patent proceedings). A transformant expressing a mutant nitrile hydratase with further improvements in drug resistance, thermostability etc. by replacement of one or more constitutional amino acids of the enzyme by other amino acids or by deletion, elimination or insertion of one or more constitutional amino acids by recombinant DNA technology also falls under the scope of the invention. The microorganism of the present invention is prepared usually by utilizing general methods known in molecular biology, biological engineering, and genetic engineering. For example, the microorganism is inoculated usually into a liquid medium such as LB medium or M9 medium and allowed to grow at a suitable culture temperature (which is generally 20 to 50° C., but may be 50° C. or more for thermophilic bacteria), and then the microorganism is separated from the culture liquid by centrifugation etc., to give the microorganism of the present invention. The treated material in the present invention refers to an extract or a trituration material of the microorganism, a separated material obtained by separating and purifying an active fraction of nitrile hydratase from the extract or the trituration material, and an immobilized material obtained by immobilizing the cell, or the extract, the trituration material of the cell or the separated material onto a suitable carrier, and these materials correspond to the treated material of the cell of the present invention insofar as they have a nitrile hydratase activity. These materials may be used alone, or simultaneously or alternately in two or more different forms. In the present invention, the conditions where the cell does not grow include, for example, those conditions where the cell or a treated material of the cell is dissolved or suspended in water, physiological saline, or an aqueous solution containing a buffer such as phosphate, an inorganic salt such as sulfate or carbonate, an alkali metal hydroxide or an amide compound dissolved therein at a suitable concentration. The aqueous solution also includes a reaction solution for producing an amide compound from a nitrile compound by the cell or the treated material of the cell. The aqueous solution further includes a culture solution in which the microorganism is cultured or a culture solution after the resting phase of growth of the microorganism or after the conclusion of culture. In addition, the aqueous solution includes a culture solution sterilized with a chemical or by heating. The oxidizing agent used in the present invention is an organic or inorganic substance having a standard electrode potential in the range of 0.1 to 2.1 V relative to a standard hydrogen electrode. A substance of less than 0.1 V has less ability as an oxidizing agent and is thus poor in the effect of maintaining and activating a nitrile hydratase activity. A substance of higher than 2.1 V has too strong ability as an oxidizing agent, thus causing deterioration of nitrile hydratase significantly and adversely reducing a nitrile hydratase activity. Examples of the oxidizing agent are listed in “Kagaku Binran” (Chemical Handbook) edited by The Chemical Society of Japan, and from the listed substances, one substance may be used, or two or more substances may be used simultaneously or alternately. Examples of such substances include oxygen, hydrogen peroxide, potassium ferricyanide, persulfate, permanganate, periodate, perchloric acid, perchlorate, nitric acid, nitrate, cerium (IV) salt, etc. Preferably, oxygen, hydrogen peroxide, potassium ferricyanide or ammonium persulfate is used as the oxidizing agent. More preferably, pure oxygen, or oxygen in the air, is supplied. In the present invention, a nitrile hydratase-containing cell or the treated material of the cell is brought into contact with the oxidizing agent under conditions where the cell does not grow, and the oxidizing agent may be brought into contact with the cell or a treated material of the cell in one portion or successively. In contact with oxygen as the oxidizing agent, an oxygen-containing gas is supplied. The gas supplied may be the air, pure oxygen, a gas containing the air and nitrogen or another gas mixed in a predetermined ratio, or a gas containing oxygen and nitrogen or another gas mixed in a predetermined ratio. Another gas referred to herein may be a single kind of gas such as nitrogen, argon or helium, or a mixture of two or more kinds of gas, and is not particularly limited insofar as it does not inhibit the reaction. For example, when the cell or a treated material of the cell is suspended in an aqueous medium in a stirring container, oxygen can be dissolved in the aqueous medium under stirring by supplying the gas into a gaseous phase in the stirring container while purging the gaseous phase. Alternatively, the gas can be dispersed and diffused by a sparger to supply oxygen in a larger gas/liquid contact area under stirring. The gas is supplied preferably after removal of miscellaneous germs by a filter for removing germs, whereby the decay of the suspension by contamination with miscellaneous germs can be prevented. In the present invention, the cell or a treated material of the cell may be contacted as such with the oxidizing agent, but is usually contacted in the form of a suspension in an aqueous medium with the oxidizing agent. As used herein, the aqueous medium is a water-containing medium, and refers to physiological saline, an aqueous solution containing a buffer such as phosphate, an inorganic salt such as sulfate or carbonate, an alkali metal hydroxide, or an amide compound dissolved therein at a suitable concentration, a reaction solution for producing an amide compound from a nitrile compound, and a culture solution after the resting phase. The concentration of the cell or a treated material of the cell upon suspension in an aqueous medium is not particularly limited, but may be usually in the range of 0.1 to 30% by weight (based on the dry weight of the cell) in the aqueous medium. When the oxidizing agent is brought into contact with the nitrile hydratase-containing cell or a treated material of the cell in the present invention, the concentration of the oxidizing agent is not particularly limited insofar as it is a concentration at which the nitrile hydratase activity can be maintained or improved, but preferably, the concentration is in the range of 1 ppm by weight to 10% by weight in the aqueous medium. When the oxidizing agent is brought into contact with the nitrile hydratase-containing cell or a treated material of the cell in the present invention, the temperature is usually 0 to 60° C., preferably 0 to 50° C., more preferably 5 to 40° C. During contact, the pH value is usually 5 to 10, preferably 5 to 9, still more preferably 6 to 8. According to the present invention, the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell can be maintained under conditions where the cell does not grow, by bringing it into contact with an oxidizing agent, and further the nitrile hydratase activity of a cell whose nitrile hydratase activity has been once reduced or a treated material of the cell can be improved by bringing it into contact with an oxidizing agent before or during the reaction. Accordingly, the contact of the nitrile hydratase-containing cell or a treated material of the cell with the oxidizing agent can be carried out at an arbitrary point in time before the conclusion of the nitrile hydration reaction. That is, the microorganism or a treated material of the microorganism may be brought into contact with the oxidizing agent before the hydration reaction, or the microorganism or a treated material of the microorganism may first be subjected to the reaction and then the oxidizing agent is subjected to the reaction thus bringing it into contact with the microorganism or a treated material of the microorganism. However, when the oxidizing agent is subjected to the reaction, side reactions different from the hydration reaction of a nitrile compound may occur; for example, when the nitrile compound is (meth)acrylonitrile, the nitrile compound itself or its corresponding product (meth)acrylamide may be polymerized, and it is therefore preferable that before the reaction, the microorganism or a treated material of the microorganism is brought into contact with the oxidizing agent. After the culture is finished, the microorganism itself or the treated microbial material is brought into contact with the oxidizing agent to improve a nitrile hydrating activity based on nitrile hydratase, and then the microorganism or the treated microbial material can be subjected as such to the reaction, but may if necessary be washed and then subjected to the reaction. For example, when the microorganism or the treated microbial material in the form of a suspension in aqueous medium is brought into contact with oxygen as the oxidizing agent, an improvement in the nitrile hydrating activity is confirmed, and thereafter, the nitrile hydrating activity can be maintained even if the dissolved oxygen in the aqueous medium is removed by passage of nitrogen, and thus the microorganism or the treated microbial material can be subjected in this state to the reaction. The nitrile compound in the present invention is a nitrile compound having about 2 to 20 carbon atoms, which includes, but is not limited to, nitriles such as aliphatic nitrile and aromatic nitrile. The aliphatic nitrile includes a saturated or unsaturated nitrile having 2 to 6 carbon atoms, for example aliphatic saturated mononitriles such as acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile and capronitrile; aliphatic saturated dinitriles such as malononitrile, succinonitrile and adiponitrile; and aliphatic unsaturated nitrites such as acrylonitrile, methacrylonitrile and crotononitrile. The aromatic nitrile includes benzonitrile, o-, m- and p-chlorobenzonitrile, o-, m- and p-fluorobenzonitrile, o-, m- and p-nitrobenzonitrile, o-, m- and p-tolunitrile, benzyl cyanide etc. In particular, acrylonitrile, methacrylonitrile, and crotononitrile can be mentioned as preferable examples. EXAMPLES Hereinafter, the present invention is described in more detail by reference to the Examples, but the present invention is not limited by the following examples. In HPLC analysis of a reaction solution in the Examples, ULTRON 80HG (50×8 φmm) was used as an HPLC column, and 10 mM aqueous phosphate solution was used as a developing solution. Acrylamide and acrylonitrile were detected by absorbance at 220 nm to determine their concentrations. The concentration of dissolved oxygen was measured by an oxygen electrode (InPro 6800/12/320 manufactured by Mettler-Toledo K.K.) and an dissolved oxygen concentration indicator (4050e model manufactured by Mettler-Toledo K.K.), after it was calibrated that 0 was indicated with 5% aqueous sodium sulfite and 10.92 ppm was indicated by saturation oxygen concentration in pure water at 10° C. previously saturated with the air. Example 1 MT-10822 strain (FERM BP-5785, see JP-A 11-253168) having a nitrile hydratase gene introduced into Escherichia coli HB101, deposited by Mitsui Chemicals, Inc., was used as the nitrile hydratase-containing cell in this example. For culture of this microbial strain, 15.0 L medium having the following composition was prepared in a 30 L culture container and sterilized with high-pressure steam at 121° C. for 20 minutes. Ampicillin was added at a final concentration of 50 μg/ml to this medium, and the microbial strain was inoculated via a platinum loop thereto and cultured at 37° C. at 700 rpm for 20 hours. About 15 hours after the culture was initiated, IPTG (isopropyl-β-D-thiogalactopyranoside) was added at a final concentration of 100 μmol/L, and the culture was continued. (Medium composition) Yeast extract  5.0 g/L Polypeptone 10.0 g/L NaCl  5.0 g/L Cobalt chloride•6H2O 10.0 mg/L Ferric sulfate•7H2O 40.0 mg/L pH 7.5 After the culture was finished, 500 mL microbial suspension wherein microbial growth had been terminated was transferred to a 1 L flask equipped with an oxygen electrode and a thermometer. The suspension was kept at 10° C. under stirring, while the air (400 N-ml/min.) was passed through the gaseous phase in the flask. 0 hour and 24 hours after storage, a part of the microbial suspension was removed. During this storage, the concentration of dissolved oxygen in the microbial suspension indicated 10.0 to 10.9 ppm. The microbial suspension, 23.0 mg, was suspended in 10.0 g of previously deoxidized 50 mM Tris-HCl buffer (pH 8.1) in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and previously deoxidized acrylonitrile was added at a final concentration of 19% by weight to this suspension and reacted at 20° C. for 2 hours under stirring. The reaction was terminated by adding 80 g of 10 mM aqueous phosphoric acid, and then the concentration of acrylamide in the reaction solution was determined by HPLC analysis. Subsequently, the concentration of the microbial suspension was determined on the basis of the dry weight of the microorganism, and then the amount of formed acrylamide per unit dry weight of the microorganism was calculated. Assuming that the amount of acrylamide formed in 0 hour of storage was 1, the amount of formed acrylamide was 1.1 in the 24th hour of storage, indicating that the nitrile hydratase activity of the nitrile hydratase was maintained stably during the storage. Example 2 500 mL microbial suspension wherein microbial growth had been terminated, obtained in the same manner as in Example 1, was transferred to a 1 L flask equipped with an oxygen electrode and a thermometer. The suspension was kept at 10° C. under stirring, while a mixture of the air (400 N-ml/min.) and nitrogen (4000 N-ml/min.) was passed through the gaseous phase in the flask. 0 hour and 24 hours after storage, a part of the microbial suspension was removed. During this storage, the concentration of dissolved oxygen in the microbial suspension indicated 1.0 to 1.5 ppm. The amount of formed acrylamide in the microbial suspension per unit dry weight of the microorganism was determined in the same manner as in Example 1. Assuming that the amount of acrylamide formed in 0 hour of storage was 1, the amount was 1.0 in the 24th hour, indicating that the nitrile hydrating activity of the nitrile hydratase was kept stably during the storage. Comparative Example 1 500 mL microbial suspension wherein microbial growth had been terminated, obtained in the same manner as in Example 1, was transferred to a 1 L flask equipped with an oxygen electrode and a thermometer. The suspension was kept at 10° C. under stirring, while nitrogen (400 N-ml/min.) was passed through the gaseous phase in the flask to deoxidize the microbial suspension under stirring. 0, 1 and 3 hours after storage, apart of the microbial suspension was removed. During this storage, the concentration of dissolved oxygen in the microbial suspension indicated 0.0 ppm. The amount of formed acrylamide in the microbial suspension per unit dry weight of the microorganism was determined in the same manner as in Example 1. Assuming that the amount of acrylamide formed in 0 hour of storage was 1, the amount was 0.45 in the first hour and 0.20 in the 3rd hour, indicating that the nitrile hydrating activity of the nitrile hydratase was reduced with time during the storage. Comparative Example 2 500 mL microbial suspension wherein microbial growth had been terminated, obtained in the same manner as in Example 1, was transferred to a 1 L flask equipped with an oxygen electrode and a thermometer. The suspension was kept at 10° C. under stirring, while nitrogen (400 N-ml/min.) was passed through the gaseous phase in the flask. The amount of formed acrylamide in 0 hour of storage in the microbial suspension per unit dry weight of the microorganism was determined in the same manner as in Example 1. 1 hour after storage, a part of the microbial suspension was removed and centrifuged (15000 G×13 minutes) in a nitrogen atmosphere to separate the microorganism only from the suspension to give a wet microorganism. The resulting microorganism, 0.20 g, was suspended in previously deoxidized pure water in a 100 ml sealable glass container previously sufficiently purged with nitrogen, to give 20.00 g suspension. The microbial suspension was kept at 20° C. for 15 minutes under stirring. The microbial suspension, 66.0 mg, was suspended in 10.0 g of previously deoxidized 50 mM Tris-HCl buffer (pH 8.1) in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and previously deoxidized acrylonitrile was added at a final concentration of 19% by weight to this suspension and reacted at 20° C. for 4 hours under stirring. The reaction was terminated by adding 80 g of 10 mM aqueous phosphoric acid, and then the concentration of acrylamide in the reaction solution was determined by HPLC analysis. Subsequently, the concentration of the microbial suspension based on the dry weight of the microorganism was determined, and then the amount of formed acrylamide per unit dry weight of the microorganism was calculated. Assuming that the amount of acrylamide formed after 1 hour of storage by the wet microorganism obtained by centrifugation was 1.0, the amount of formed acrylamide was 2.9 in 0 hour of storage, and it was thus confirmed that the nitrile hydratase activity of the wet microorganism obtained in Comparative Example 2 was reduced. Examples 3 to 9 A microbial suspension wherein microbial growth had been terminated, obtained in the same manner as in Example 1, was centrifuged (15000 G×15 minutes) to separate the microorganism only from the suspension to give a wet microorganism. The resulting microorganism, 0.20 g, was suspended in previously deoxidized pure water in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and potassium ferricyanide was added and suspended as an oxidizing agent at a final concentration shown in Table 1 to give 20.00 g suspension. Separately, an oxidizing agent-free microbial suspension was prepared in the same manner. The microbial suspension was kept at 20° C. for 15 minutes under stirring. The microbial suspension, 66.0 mg, was suspended in 10.0 g of previously deoxidized 50 mM Tris-HCl buffer (pH 8.1) in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and previously deoxidized acrylonitrile was added at a final concentration of 19% by weight to this suspension and reacted at 20° C. for 4 hours under stirring. The reaction was terminated by adding 80 g of 10 mM aqueous phosphoric acid, and then the concentration of acrylamide in the reaction solution was determined by HPLC analysis. Subsequently, the concentration of the microbial suspension based on the dry weight of the microorganism was determined, and then the amount of formed acrylamide per unit dry weight of the microorganism was calculated. Assuming that the amount of formed acrylamide per unit dry weight of the microorganism in the absence of the oxidizing agent is 1.0, the amounts of formed acrylamide in Examples 3 to 9 are shown as relative values in Table 1. Examples 10 to 11 The amount of acrylamide formed per unit dry weight of the microorganism was determined in the same manner as in Example 3 except that in place of potassium ferricyanide, ammonium persulfate was added and suspended as an oxidizing agent at a concentration shown in Table 1. Assuming that the amount of formed acrylamide per unit dry weight of the microorganism in the absence of the oxidizing agent is 1.0, the amounts of formed acrylamide in Examples 10 to 11 are shown as relative values in Table 1. Example 12 The amount of acrylamide formed per unit dry weight of the microorganism was determined in the same manner as in Example 3 except that in place of potassium ferricyanide, 30 wt % aqueous hydrogen peroxide was added and suspended as an oxidizing agent at a concentration shown in Table 1. Assuming that the amount of formed acrylamide per unit dry weight of the microorganism in the absence of the oxidizing agent is 1.0, the amount of formed acrylamide in Example 12 is shown as a relative value in Table 1. TABLE 1 AMOUNT OF CON- ACRYLAMIDE CENTRATION FORMED (REL- REAGENT (WT %) ATIVE VALUE) — — NOT ADDED 1.0 EXAMPLE 3 POTASSIUM 0.20 1.4 FERRICYANIDE EXAMPLE 4 POTASSIUM 0.39 1.7 FERRICYANIDE EXAMPLE 5 POTASSIUM 0.81 2.0 FERRICYANIDE EXAMPLE 6 POTASSIUM 1.9 2.4 FERRICYANIDE EXAMPLE 7 POTASSIUM 1.6 2.6 FERRICYANIDE EXAMPLE 8 POTASSIUM 2.0 2.9 FERRICYANIDE EXAMPLE 9 POTASSIUM 10.0 2.9 FERRICYANIDE EXAMPLE 10 AMMONIUM 1.3 1.6 PERSULFATE EXAMPLE 11 AMMONIUM 2.7 1.6 PERSULFATE EXAMPLE 12 HYDROGEN 0.21 2.4 PEROXIDE From the results shown above, it can be seen that when the microorganism is brought into contact with an oxidizing agent such as potassium ferricyanide, hydrogen peroxide or ammonium persulfate, the nitrile hydrating activity of the nitrile hydratase is improved. Example 13 0.20 g wet microorganism obtained in the same manner as in Example 3 was suspended in previously deoxidized pure water in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and potassium ferricyanide was added and suspended as an oxidizing agent at a final concentration of 0.77% by weight to give 20.00 g suspension. The microbial suspension was kept at 20° C. under stirring. 0 minute, 10 minutes, 2 hours and 24 hours after the stirring was initiated, a small amount of the microbial suspension was collected, and the amount of formed acrylamide per unit dry weight of the microorganism was determined in the same manner as in Example 3. Assuming that the amount of acrylamide formed in 0 minute of stirring by per unit dry weight of the microorganism is 1, the amounts of acrylamide formed in the 10th minute, in the second hour and in the 24th hour after initiation of stirring are shown as relative values in Table 2. TABLE 2 AMOUNT OF ACRYLAMIDE STIRRING TIME FORMED (RELATIVE VALUE) EXAMPLE 13  0 HOUR 1.0 10 MINUTES 1.7  2 HOURS 2.5 24 HOURS 2.4 From the results shown above, it can be seen that when the microorganism is brought into contact with an oxidizing agent such as potassium ferricyanide, the nitrile hydrating activity of the nitrile hydratase is improved depending on the contact time, and simultaneously the improved activity is maintained. Example 14 A wet microorganism was obtained in the same manner as in Example 3. The resulting wet microorganism, 1.5 g, was suspended in 48.5 g pure water in a 100 mL flask equipped with an oxygen electrode and a thermometer. The suspension was kept at 10° C. under stirring, while the air (40 N-ml/min.) was passed through the gaseous phase in the flask. 0, 1, 2, 3, 7 and 19 days after storage, a part of the microbial suspension was removed. During this storage, the concentration of dissolved oxygen in the microbial suspension indicated 10.0 to 10.9 ppm. The amount of formed acrylamide in each of the collected microbial suspensions per unit dry weight of the microorganism was determined in the same manner as in Example 3. Assuming that the amount of acrylamide formed on 0 day of storage by per unit dry weight of the microorganism is 1, the amounts of acrylamide formed on the first day, second day, third day, seventh day and nineteenth day of storage are shown as relative values in Table 3. Example 15 A wet microorganism was obtained in the same manner as in Example 3. The resulting wet microorganism, 1.5 g, was suspended in 48.5 g pure water in a 100 mL flask equipped with an oxygen electrode and a thermometer. The suspension was kept at 10° C. under stirring, while a mixture of the air (40 N-ml/min.) and nitrogen (400 N-ml/min.) was passed through the gaseous phase in the flask. 0, 1, 2, 3, 7 and 19 days after storage, a part of the microbial suspension was removed. During this storage, the concentration of dissolved oxygen in the microbial suspension indicated 1.0 to 1.5 ppm. The amount of formed acrylamide in each of the collected microbial suspensions per unit dry weight of the microorganism was determined in the same manner as in Example 3. Assuming that the amount of acrylamide formed on 0 day of storage by per unit dry weight of the microorganism is 1, the amounts of acrylamide formed on the first day, second day, third day, seventh day and nineteenth day of storage are shown as relative values in Table 3. TABLE 3 NUMBER OF DAYS FOR STORAGE 0 1 2 3 7 19 EXAMPLE 14 1.0 2.4 2.3 2.4 2.5 2.5 EXAMPLE 15 1.0 1.6 2.3 2.4 2.5 2.4 From the results shown above, it can be seen that when the microorganism is brought into contact with oxygen as the oxidizing agent, the nitrile hydrating activity of the nitrile hydratase is improved depending on the contact time, and after a predetermined time, the nitrile hydrating activity is highly and stably maintained. Examples 16 to 18 0.20 g wet microorganism obtained in the same manner as in Example 3 was suspended in previously deoxidized pure water in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and potassium ferricyanide was added and suspended as an oxidizing agent at a final concentration of 2.0% by weight, and the suspension was adjusted with an aqueous sodium hydroxide solution or sulfuric acid to a pH value shown in Table 4 to give 20.00 g suspension. Separately, a microbial suspension wherein the oxidizing agent was not added and the pH value was not adjusted was also prepared in the same manner. The microbial suspension was kept at 20° C. for 15 minutes under stirring. The amount of formed acrylamide per unit dry weight of the microorganism was determined in the same manner as in Example 3. Assuming that the amount of acrylamide formed per unit dry weight of the microorganism in the case where the oxidizing agent was not added and the pH value was not regulated is 1, the amounts of acrylamide formed in Examples 16 to 18 are shown as relative values in Table 4. TABLE 4 AMOUNT OF ACRYLAMIDE BUFFER FORMED (REL- REAGENT SOLUTION PH ATIVE VALUE) — NOT ADDED NOT 1.0 REGULATED (7.1) EXAMPLE 16 POTASSIUM 5.0 1.8 FERRICYANIDE EXAMPLE 17 POTASSIUM 6.7 2.9 FERRICYANIDE EXAMPLE 18 POTASSIUM 10.0 2.0 FERRICYANIDE Examples 19 to 21 0.20 g wet microorganism obtained in the same manner as in Example 3 was suspended in previously deoxidized pure water in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and potassium ferricyanide was added and suspended as an oxidizing agent at a final concentration of 2.0% by weight to give 20.00 g suspension. Separately, a microbial suspension wherein the oxidizing agent was not added was also prepared in the same manner. The microbial suspension was stirred for 15 minutes at a temperature shown in Table 6. The amount of formed acrylamide per unit dry weight of the microorganism was determined in the same manner as in Example 3. Assuming that the amount of acrylamide formed per unit dry weight of the microorganism in the suspension stirred at a temperature of 20° C. in the absence of the oxidizing agent is 1, the amounts of acrylamide formed in Examples 19 to 21 are shown as relative values in Table 5. TABLE 5 TEMPERATURE AMOUNT OF OF THE ACRYLAMIDE SUSPENSION FORMED (REL- REAGENT (° C.) ATIVE VALUE) — NOT ADDED 20 1.0 EXAMPLE 19 POTASSIUM 0 3.2 FERRICYANIDE EXAMPLE 20 POTASSIUM 20 2.9 FERRICYANIDE EXAMPLE 21 POTASSIUM 60 1.4 FERRICYANIDE The present invention can not only easily maintain the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell under conditions where the cell does not grow, but also improve the nitrile hydratase activity of a nitrile hydratase-containing cell whose activity was once reduced or a treated material of the cell, and thus the present invention is industrially advantageous.
The object of this invention is to provide a method which not only maintains the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell under conditions where the cell does not grow, but also improves the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell whose activity was once reduced. This invention relates to a method of maintaining or improving a nitrile hydratase activity which comprises bringing a nitrile hydratase-containing cell or a treated material of the cell into contact with an oxidizing agent under conditions where the cell does not grow, as well as a method of producing an amide compound from a nitrile compound, which comprises using the cell brought into contact with an oxidizing agent or a treated material of the cell.
Summarize the key points of the given document.
[ "This application claims priority under 35 U.S.C. § 119 to Application No. 2003-151214, filed in Japan on May 28, 2003;", "the entire content of which is hereby incorporated by reference.", "BACKGROUND OF THE INVENTION 1.", "Field of the Invention The present invention relates to a method of maintaining or improving the activity of industrially useful nitrile hydratase.", "The activity referred to herein is a nitrile hydrating activity determined by a method described in the Examples.", "Description of the Related Art The nitrile hydrating activity of nitrile hydratase is unstable and easily reduced with time.", "For preventing such reduction in the nitrile hydrating activity of nitrile hydratase with time to maintain the activity, a method which comprises adding at least one compound selected from a nitrile, an amide, an organic acid and a salt thereof as a stabilizer to a suspension or solution of a nitrile hydratase-containing microorganism or a treated material of the microorganism is disclosed (see, for example, JP-B 5-43351 and JP-B 4-48435).", "A storage method wherein a microorganism or a treated microbial material is in a state suspended in an aqueous medium and the aqueous medium is neutral or weakly basic and having dissolved therein an inorganic salt at a concentration of 100 mM to its saturated concentration is also disclosed (see, for example, JP-A 8-112089).", "However, both the methods are effective only in maintaining a nitrile hydratase activity, and an effect of further increasing the nitrile hydratase activity is not reported therein.", "As a method of increasing a nitrile hydrating activity by producing a nitrile hydratase-containing microorganism through culture and then subjecting the resulting microorganism or a treated material of the microorganism to some treatment, a method which comprises irradiating the resulting Gram-positive microorganism having a nitrile hydratase activity with light is disclosed (see, for example, JP-B2-35).", "However, this method is effective only in increasing the nitrile hydratase activity of the microorganism obtained through culture, and does not improve the nitrile hydratase activity of a microorganism whose activity was reduced.", "In addition, this method is irrelevant to maintenance of nitrile hydratase activity.", "It is also reported that oxygen is necessary for culturing a nitrile hydratase-containing microorganism, and the concentration of dissolved oxygen during culture is maintained in the range of from 1 ppm to its saturated concentration, whereby the growth of the microorganism can be improved, and simultaneously the microorganism expressing a nitrile hydratase activity at high levels can be obtained (see, for example, JP-A 2002-17339).", "However, it is merely reported in this method that during culture, that is, under conditions where the nitrile hydratase-containing microorganism grows, there is the optimum concentration of dissolved oxygen in a culture solution in order to express a nitrile hydratase activity, and there is no description therein of maintenance and improvement of the nitrile hydratase activity under conditions where the nitrile hydratase-containing microorganism does not grow, that is, after the conclusion of culture.", "The detailed mechanism of expression and reduction of nitrile hydratase activity is not completely elucidated, but it is described that for example, the reduction of the nitrile hydrating activity of iron-type nitrile hydratase derived from Rhodococcus sp.", "N-771 is attributable to oxidation, with oxygen in the air, of cysteinesulfenic acid coordinated with non-heme iron (III) as central metal into cysteinesulfinic acid (see, for example, M. Okada, M. Tsujimura and I. Endo: RIKEN Review, No. 41, p. 58-60 (2001)).", "It is also described that for example, the activity of iron-type nitrile hydratase derived from Rhodococcus sp.", "N-771 is lost when trivalent iron as central metal is reduced to divalent iron by 2-cyano-2-propylhydroxy peroxide while cysteinesulfenic acid is oxidized into cysteinesulfinic acid (see, for example, M. Okada, M. Tsujimura and I. Endo: New Development of Reaction in Organic Chemistry (in Japanese), No. 3, p. 17-20 (2001).", "It is also described that the structure of nitrile hydratase with cobalt as central metal, derived from Rhodococcus rhodochrous J1, is not determined, but is estimated to be similar to that of iron nitrile hydratase (see, for example, P. K. Mascharak, Coordination Chemistry Reviews, No. 225, p. 201-214 (2002)).", "SUMMARY OF THE INVENTION The object of the present invention is to provide a method which not only maintains the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell under conditions where the cell does not grow, but also improves the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell whose activity was once reduced.", "The present inventors made extensive study to solve the problem, and as a result, we found that the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell can be maintained by bringing it into contact with an oxidizing agent under conditions where the cell does not grow, and further the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell whose activity was once reduced can be improved by bringing it into contact with an oxidizing agent before or during reaction, and the present invention was thereby arrived at.", "That is, the present invention provides: (1) A method of maintaining or improving a nitrile hydratase activity, which comprises bringing a nitrile hydratase-containing cell or a treated material of the cell into contact with an oxidizing agent under conditions where the cell does not grow.", "(2) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the oxidizing agent is an oxidizing agent having a standard electrode potential in the range of 0.1 to 2.1 V relative to a standard hydrogen electrode.", "(3) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the oxidizing agent is at least one member selected from the group consisting of oxygen, hydrogen peroxide, potassium ferricyanide and ammonium persulfate.", "(4) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (3), wherein the oxygen as the oxidizing agent is supplied as an oxygen-containing gas.", "(5) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the concentration of the oxidizing agent is in the range of 1 ppm by weight to 10% by weight.", "(6) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the temperature in contact with the oxidizing agent is in the range of 0 to 60° C. (7) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the pH value in contact with the oxidizing agent is in the range of 5 to 10.", "(8) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the nitrile hydratase is a nitrile hydratase containing cobalt in its molecule.", "(9) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein a cell where the nitrile hydratase containing cobalt in its molecule is expressed by genetic recombination, or a treated material of the cell, is brought into contact with the oxidizing agent under conditions where the cell does not grow.", "(10) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the cell is a nitrile hydratase-containing microorganism or a treated material of the microorganism.", "(11) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (10), wherein the microorganism is a genetically engineered microorganism.", "(12) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (11), wherein the genetically engineered microorganism is genetically engineered Escherichia coli.", "(13) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (12), wherein a host of the genetically engineered Escherichia coli is W3110 strain (ATCC27325), HB101 strain (ATCC33694), JM109 strain (ATCC53223) or WA802 strain (ATCC33526), each of which is derived from Escherichia coli K-12.", "(14) The method of maintaining or improving a nitrile hydratase activity according to the above-mentioned (1), wherein the nitrile hydratase-containing cell or a treated material of the cell is used for producing an amide compound from a nitrile compound.", "(15) A method of producing an amide compound from a nitrile compound, which comprises contacting a nitrile compound with the nitrile hydratase-containing cell or a treated material of the cell obtained by the method described in any one of the above-mentioned (1) to (14).", "DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention is described in more detail.", "The nitrile hydratase referred to in the present invention is an enzyme having an ability to hydrate a nitrile group of a nitrile compound to form the corresponding amide compound.", "The cell referred to in the present invention may be any one of microorganisms, plant cells and animal cells.", "The nitrile hydratase-containing microorganism is not particularly limited insofar as it is a microorganism having an ability to hydrate a nitrile group of a nitrile compound to form the corresponding amide compound.", "Examples thereof include Pseudonocardia thermophila JCM3095 , Achromobacter xerosis IFO12668 and Rhodococcus rhodochrous J1.", "The present invention also encompasses a transformant wherein a nitrile hydratase gene cloned from the above microorganism is expressed in an arbitrary host.", "The arbitrary host includes Escherichia coli , microorganisms of the genus Bacillus , such as Bacillus subtilis , yeasts, Actinomyces , and filamentous fungi.", "The host of genetically engineered Escherichia coli includes, for example, W3110 strain (ATCC27325), HB101 strain (ATCC33694), JM109 strain (ATCC53223) and WA802 strain (ATCC33526), each of which is derived from Escherichia coli K-12.", "Concrete examples thereof include MT-10822 (which was deposited as FERM BP-5785 on Feb. 7, 1996 with the National Institute of Bioscience and Human-Technology (Higashi 1-1-3, Tsukuba City, Ibaraki Pref.", ", JP), the Agency of Industrial Science and Technology, the Ministry of International Trade and Industry, Japan, under the Budapest Treaty on international approval of microbial deposition in patent proceedings).", "A transformant expressing a mutant nitrile hydratase with further improvements in drug resistance, thermostability etc.", "by replacement of one or more constitutional amino acids of the enzyme by other amino acids or by deletion, elimination or insertion of one or more constitutional amino acids by recombinant DNA technology also falls under the scope of the invention.", "The microorganism of the present invention is prepared usually by utilizing general methods known in molecular biology, biological engineering, and genetic engineering.", "For example, the microorganism is inoculated usually into a liquid medium such as LB medium or M9 medium and allowed to grow at a suitable culture temperature (which is generally 20 to 50° C., but may be 50° C. or more for thermophilic bacteria), and then the microorganism is separated from the culture liquid by centrifugation etc.", ", to give the microorganism of the present invention.", "The treated material in the present invention refers to an extract or a trituration material of the microorganism, a separated material obtained by separating and purifying an active fraction of nitrile hydratase from the extract or the trituration material, and an immobilized material obtained by immobilizing the cell, or the extract, the trituration material of the cell or the separated material onto a suitable carrier, and these materials correspond to the treated material of the cell of the present invention insofar as they have a nitrile hydratase activity.", "These materials may be used alone, or simultaneously or alternately in two or more different forms.", "In the present invention, the conditions where the cell does not grow include, for example, those conditions where the cell or a treated material of the cell is dissolved or suspended in water, physiological saline, or an aqueous solution containing a buffer such as phosphate, an inorganic salt such as sulfate or carbonate, an alkali metal hydroxide or an amide compound dissolved therein at a suitable concentration.", "The aqueous solution also includes a reaction solution for producing an amide compound from a nitrile compound by the cell or the treated material of the cell.", "The aqueous solution further includes a culture solution in which the microorganism is cultured or a culture solution after the resting phase of growth of the microorganism or after the conclusion of culture.", "In addition, the aqueous solution includes a culture solution sterilized with a chemical or by heating.", "The oxidizing agent used in the present invention is an organic or inorganic substance having a standard electrode potential in the range of 0.1 to 2.1 V relative to a standard hydrogen electrode.", "A substance of less than 0.1 V has less ability as an oxidizing agent and is thus poor in the effect of maintaining and activating a nitrile hydratase activity.", "A substance of higher than 2.1 V has too strong ability as an oxidizing agent, thus causing deterioration of nitrile hydratase significantly and adversely reducing a nitrile hydratase activity.", "Examples of the oxidizing agent are listed in “Kagaku Binran”", "(Chemical Handbook) edited by The Chemical Society of Japan, and from the listed substances, one substance may be used, or two or more substances may be used simultaneously or alternately.", "Examples of such substances include oxygen, hydrogen peroxide, potassium ferricyanide, persulfate, permanganate, periodate, perchloric acid, perchlorate, nitric acid, nitrate, cerium (IV) salt, etc.", "Preferably, oxygen, hydrogen peroxide, potassium ferricyanide or ammonium persulfate is used as the oxidizing agent.", "More preferably, pure oxygen, or oxygen in the air, is supplied.", "In the present invention, a nitrile hydratase-containing cell or the treated material of the cell is brought into contact with the oxidizing agent under conditions where the cell does not grow, and the oxidizing agent may be brought into contact with the cell or a treated material of the cell in one portion or successively.", "In contact with oxygen as the oxidizing agent, an oxygen-containing gas is supplied.", "The gas supplied may be the air, pure oxygen, a gas containing the air and nitrogen or another gas mixed in a predetermined ratio, or a gas containing oxygen and nitrogen or another gas mixed in a predetermined ratio.", "Another gas referred to herein may be a single kind of gas such as nitrogen, argon or helium, or a mixture of two or more kinds of gas, and is not particularly limited insofar as it does not inhibit the reaction.", "For example, when the cell or a treated material of the cell is suspended in an aqueous medium in a stirring container, oxygen can be dissolved in the aqueous medium under stirring by supplying the gas into a gaseous phase in the stirring container while purging the gaseous phase.", "Alternatively, the gas can be dispersed and diffused by a sparger to supply oxygen in a larger gas/liquid contact area under stirring.", "The gas is supplied preferably after removal of miscellaneous germs by a filter for removing germs, whereby the decay of the suspension by contamination with miscellaneous germs can be prevented.", "In the present invention, the cell or a treated material of the cell may be contacted as such with the oxidizing agent, but is usually contacted in the form of a suspension in an aqueous medium with the oxidizing agent.", "As used herein, the aqueous medium is a water-containing medium, and refers to physiological saline, an aqueous solution containing a buffer such as phosphate, an inorganic salt such as sulfate or carbonate, an alkali metal hydroxide, or an amide compound dissolved therein at a suitable concentration, a reaction solution for producing an amide compound from a nitrile compound, and a culture solution after the resting phase.", "The concentration of the cell or a treated material of the cell upon suspension in an aqueous medium is not particularly limited, but may be usually in the range of 0.1 to 30% by weight (based on the dry weight of the cell) in the aqueous medium.", "When the oxidizing agent is brought into contact with the nitrile hydratase-containing cell or a treated material of the cell in the present invention, the concentration of the oxidizing agent is not particularly limited insofar as it is a concentration at which the nitrile hydratase activity can be maintained or improved, but preferably, the concentration is in the range of 1 ppm by weight to 10% by weight in the aqueous medium.", "When the oxidizing agent is brought into contact with the nitrile hydratase-containing cell or a treated material of the cell in the present invention, the temperature is usually 0 to 60° C., preferably 0 to 50° C., more preferably 5 to 40° C. During contact, the pH value is usually 5 to 10, preferably 5 to 9, still more preferably 6 to 8.", "According to the present invention, the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell can be maintained under conditions where the cell does not grow, by bringing it into contact with an oxidizing agent, and further the nitrile hydratase activity of a cell whose nitrile hydratase activity has been once reduced or a treated material of the cell can be improved by bringing it into contact with an oxidizing agent before or during the reaction.", "Accordingly, the contact of the nitrile hydratase-containing cell or a treated material of the cell with the oxidizing agent can be carried out at an arbitrary point in time before the conclusion of the nitrile hydration reaction.", "That is, the microorganism or a treated material of the microorganism may be brought into contact with the oxidizing agent before the hydration reaction, or the microorganism or a treated material of the microorganism may first be subjected to the reaction and then the oxidizing agent is subjected to the reaction thus bringing it into contact with the microorganism or a treated material of the microorganism.", "However, when the oxidizing agent is subjected to the reaction, side reactions different from the hydration reaction of a nitrile compound may occur;", "for example, when the nitrile compound is (meth)acrylonitrile, the nitrile compound itself or its corresponding product (meth)acrylamide may be polymerized, and it is therefore preferable that before the reaction, the microorganism or a treated material of the microorganism is brought into contact with the oxidizing agent.", "After the culture is finished, the microorganism itself or the treated microbial material is brought into contact with the oxidizing agent to improve a nitrile hydrating activity based on nitrile hydratase, and then the microorganism or the treated microbial material can be subjected as such to the reaction, but may if necessary be washed and then subjected to the reaction.", "For example, when the microorganism or the treated microbial material in the form of a suspension in aqueous medium is brought into contact with oxygen as the oxidizing agent, an improvement in the nitrile hydrating activity is confirmed, and thereafter, the nitrile hydrating activity can be maintained even if the dissolved oxygen in the aqueous medium is removed by passage of nitrogen, and thus the microorganism or the treated microbial material can be subjected in this state to the reaction.", "The nitrile compound in the present invention is a nitrile compound having about 2 to 20 carbon atoms, which includes, but is not limited to, nitriles such as aliphatic nitrile and aromatic nitrile.", "The aliphatic nitrile includes a saturated or unsaturated nitrile having 2 to 6 carbon atoms, for example aliphatic saturated mononitriles such as acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile and capronitrile;", "aliphatic saturated dinitriles such as malononitrile, succinonitrile and adiponitrile;", "and aliphatic unsaturated nitrites such as acrylonitrile, methacrylonitrile and crotononitrile.", "The aromatic nitrile includes benzonitrile, o-, m- and p-chlorobenzonitrile, o-, m- and p-fluorobenzonitrile, o-, m- and p-nitrobenzonitrile, o-, m- and p-tolunitrile, benzyl cyanide etc.", "In particular, acrylonitrile, methacrylonitrile, and crotononitrile can be mentioned as preferable examples.", "EXAMPLES Hereinafter, the present invention is described in more detail by reference to the Examples, but the present invention is not limited by the following examples.", "In HPLC analysis of a reaction solution in the Examples, ULTRON 80HG (50×8 φmm) was used as an HPLC column, and 10 mM aqueous phosphate solution was used as a developing solution.", "Acrylamide and acrylonitrile were detected by absorbance at 220 nm to determine their concentrations.", "The concentration of dissolved oxygen was measured by an oxygen electrode (InPro 6800/12/320 manufactured by Mettler-Toledo K.K.) and an dissolved oxygen concentration indicator (4050e model manufactured by Mettler-Toledo K.K.), after it was calibrated that 0 was indicated with 5% aqueous sodium sulfite and 10.92 ppm was indicated by saturation oxygen concentration in pure water at 10° C. previously saturated with the air.", "Example 1 MT-10822 strain (FERM BP-5785, see JP-A 11-253168) having a nitrile hydratase gene introduced into Escherichia coli HB101, deposited by Mitsui Chemicals, Inc., was used as the nitrile hydratase-containing cell in this example.", "For culture of this microbial strain, 15.0 L medium having the following composition was prepared in a 30 L culture container and sterilized with high-pressure steam at 121° C. for 20 minutes.", "Ampicillin was added at a final concentration of 50 μg/ml to this medium, and the microbial strain was inoculated via a platinum loop thereto and cultured at 37° C. at 700 rpm for 20 hours.", "About 15 hours after the culture was initiated, IPTG (isopropyl-β-D-thiogalactopyranoside) was added at a final concentration of 100 μmol/L, and the culture was continued.", "(Medium composition) Yeast extract 5.0 g/L Polypeptone 10.0 g/L NaCl 5.0 g/L Cobalt chloride•6H2O 10.0 mg/L Ferric sulfate•7H2O 40.0 mg/L pH 7.5 After the culture was finished, 500 mL microbial suspension wherein microbial growth had been terminated was transferred to a 1 L flask equipped with an oxygen electrode and a thermometer.", "The suspension was kept at 10° C. under stirring, while the air (400 N-ml/min.) was passed through the gaseous phase in the flask.", "0 hour and 24 hours after storage, a part of the microbial suspension was removed.", "During this storage, the concentration of dissolved oxygen in the microbial suspension indicated 10.0 to 10.9 ppm.", "The microbial suspension, 23.0 mg, was suspended in 10.0 g of previously deoxidized 50 mM Tris-HCl buffer (pH 8.1) in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and previously deoxidized acrylonitrile was added at a final concentration of 19% by weight to this suspension and reacted at 20° C. for 2 hours under stirring.", "The reaction was terminated by adding 80 g of 10 mM aqueous phosphoric acid, and then the concentration of acrylamide in the reaction solution was determined by HPLC analysis.", "Subsequently, the concentration of the microbial suspension was determined on the basis of the dry weight of the microorganism, and then the amount of formed acrylamide per unit dry weight of the microorganism was calculated.", "Assuming that the amount of acrylamide formed in 0 hour of storage was 1, the amount of formed acrylamide was 1.1 in the 24th hour of storage, indicating that the nitrile hydratase activity of the nitrile hydratase was maintained stably during the storage.", "Example 2 500 mL microbial suspension wherein microbial growth had been terminated, obtained in the same manner as in Example 1, was transferred to a 1 L flask equipped with an oxygen electrode and a thermometer.", "The suspension was kept at 10° C. under stirring, while a mixture of the air (400 N-ml/min.) and nitrogen (4000 N-ml/min.) was passed through the gaseous phase in the flask.", "0 hour and 24 hours after storage, a part of the microbial suspension was removed.", "During this storage, the concentration of dissolved oxygen in the microbial suspension indicated 1.0 to 1.5 ppm.", "The amount of formed acrylamide in the microbial suspension per unit dry weight of the microorganism was determined in the same manner as in Example 1.", "Assuming that the amount of acrylamide formed in 0 hour of storage was 1, the amount was 1.0 in the 24th hour, indicating that the nitrile hydrating activity of the nitrile hydratase was kept stably during the storage.", "Comparative Example 1 500 mL microbial suspension wherein microbial growth had been terminated, obtained in the same manner as in Example 1, was transferred to a 1 L flask equipped with an oxygen electrode and a thermometer.", "The suspension was kept at 10° C. under stirring, while nitrogen (400 N-ml/min.) was passed through the gaseous phase in the flask to deoxidize the microbial suspension under stirring.", "0, 1 and 3 hours after storage, apart of the microbial suspension was removed.", "During this storage, the concentration of dissolved oxygen in the microbial suspension indicated 0.0 ppm.", "The amount of formed acrylamide in the microbial suspension per unit dry weight of the microorganism was determined in the same manner as in Example 1.", "Assuming that the amount of acrylamide formed in 0 hour of storage was 1, the amount was 0.45 in the first hour and 0.20 in the 3rd hour, indicating that the nitrile hydrating activity of the nitrile hydratase was reduced with time during the storage.", "Comparative Example 2 500 mL microbial suspension wherein microbial growth had been terminated, obtained in the same manner as in Example 1, was transferred to a 1 L flask equipped with an oxygen electrode and a thermometer.", "The suspension was kept at 10° C. under stirring, while nitrogen (400 N-ml/min.) was passed through the gaseous phase in the flask.", "The amount of formed acrylamide in 0 hour of storage in the microbial suspension per unit dry weight of the microorganism was determined in the same manner as in Example 1.", "1 hour after storage, a part of the microbial suspension was removed and centrifuged (15000 G×13 minutes) in a nitrogen atmosphere to separate the microorganism only from the suspension to give a wet microorganism.", "The resulting microorganism, 0.20 g, was suspended in previously deoxidized pure water in a 100 ml sealable glass container previously sufficiently purged with nitrogen, to give 20.00 g suspension.", "The microbial suspension was kept at 20° C. for 15 minutes under stirring.", "The microbial suspension, 66.0 mg, was suspended in 10.0 g of previously deoxidized 50 mM Tris-HCl buffer (pH 8.1) in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and previously deoxidized acrylonitrile was added at a final concentration of 19% by weight to this suspension and reacted at 20° C. for 4 hours under stirring.", "The reaction was terminated by adding 80 g of 10 mM aqueous phosphoric acid, and then the concentration of acrylamide in the reaction solution was determined by HPLC analysis.", "Subsequently, the concentration of the microbial suspension based on the dry weight of the microorganism was determined, and then the amount of formed acrylamide per unit dry weight of the microorganism was calculated.", "Assuming that the amount of acrylamide formed after 1 hour of storage by the wet microorganism obtained by centrifugation was 1.0, the amount of formed acrylamide was 2.9 in 0 hour of storage, and it was thus confirmed that the nitrile hydratase activity of the wet microorganism obtained in Comparative Example 2 was reduced.", "Examples 3 to 9 A microbial suspension wherein microbial growth had been terminated, obtained in the same manner as in Example 1, was centrifuged (15000 G×15 minutes) to separate the microorganism only from the suspension to give a wet microorganism.", "The resulting microorganism, 0.20 g, was suspended in previously deoxidized pure water in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and potassium ferricyanide was added and suspended as an oxidizing agent at a final concentration shown in Table 1 to give 20.00 g suspension.", "Separately, an oxidizing agent-free microbial suspension was prepared in the same manner.", "The microbial suspension was kept at 20° C. for 15 minutes under stirring.", "The microbial suspension, 66.0 mg, was suspended in 10.0 g of previously deoxidized 50 mM Tris-HCl buffer (pH 8.1) in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and previously deoxidized acrylonitrile was added at a final concentration of 19% by weight to this suspension and reacted at 20° C. for 4 hours under stirring.", "The reaction was terminated by adding 80 g of 10 mM aqueous phosphoric acid, and then the concentration of acrylamide in the reaction solution was determined by HPLC analysis.", "Subsequently, the concentration of the microbial suspension based on the dry weight of the microorganism was determined, and then the amount of formed acrylamide per unit dry weight of the microorganism was calculated.", "Assuming that the amount of formed acrylamide per unit dry weight of the microorganism in the absence of the oxidizing agent is 1.0, the amounts of formed acrylamide in Examples 3 to 9 are shown as relative values in Table 1.", "Examples 10 to 11 The amount of acrylamide formed per unit dry weight of the microorganism was determined in the same manner as in Example 3 except that in place of potassium ferricyanide, ammonium persulfate was added and suspended as an oxidizing agent at a concentration shown in Table 1.", "Assuming that the amount of formed acrylamide per unit dry weight of the microorganism in the absence of the oxidizing agent is 1.0, the amounts of formed acrylamide in Examples 10 to 11 are shown as relative values in Table 1.", "Example 12 The amount of acrylamide formed per unit dry weight of the microorganism was determined in the same manner as in Example 3 except that in place of potassium ferricyanide, 30 wt % aqueous hydrogen peroxide was added and suspended as an oxidizing agent at a concentration shown in Table 1.", "Assuming that the amount of formed acrylamide per unit dry weight of the microorganism in the absence of the oxidizing agent is 1.0, the amount of formed acrylamide in Example 12 is shown as a relative value in Table 1.", "TABLE 1 AMOUNT OF CON- ACRYLAMIDE CENTRATION FORMED (REL- REAGENT (WT %) ATIVE VALUE) — — NOT ADDED 1.0 EXAMPLE 3 POTASSIUM 0.20 1.4 FERRICYANIDE EXAMPLE 4 POTASSIUM 0.39 1.7 FERRICYANIDE EXAMPLE 5 POTASSIUM 0.81 2.0 FERRICYANIDE EXAMPLE 6 POTASSIUM 1.9 2.4 FERRICYANIDE EXAMPLE 7 POTASSIUM 1.6 2.6 FERRICYANIDE EXAMPLE 8 POTASSIUM 2.0 2.9 FERRICYANIDE EXAMPLE 9 POTASSIUM 10.0 2.9 FERRICYANIDE EXAMPLE 10 AMMONIUM 1.3 1.6 PERSULFATE EXAMPLE 11 AMMONIUM 2.7 1.6 PERSULFATE EXAMPLE 12 HYDROGEN 0.21 2.4 PEROXIDE From the results shown above, it can be seen that when the microorganism is brought into contact with an oxidizing agent such as potassium ferricyanide, hydrogen peroxide or ammonium persulfate, the nitrile hydrating activity of the nitrile hydratase is improved.", "Example 13 0.20 g wet microorganism obtained in the same manner as in Example 3 was suspended in previously deoxidized pure water in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and potassium ferricyanide was added and suspended as an oxidizing agent at a final concentration of 0.77% by weight to give 20.00 g suspension.", "The microbial suspension was kept at 20° C. under stirring.", "0 minute, 10 minutes, 2 hours and 24 hours after the stirring was initiated, a small amount of the microbial suspension was collected, and the amount of formed acrylamide per unit dry weight of the microorganism was determined in the same manner as in Example 3.", "Assuming that the amount of acrylamide formed in 0 minute of stirring by per unit dry weight of the microorganism is 1, the amounts of acrylamide formed in the 10th minute, in the second hour and in the 24th hour after initiation of stirring are shown as relative values in Table 2.", "TABLE 2 AMOUNT OF ACRYLAMIDE STIRRING TIME FORMED (RELATIVE VALUE) EXAMPLE 13 0 HOUR 1.0 10 MINUTES 1.7 2 HOURS 2.5 24 HOURS 2.4 From the results shown above, it can be seen that when the microorganism is brought into contact with an oxidizing agent such as potassium ferricyanide, the nitrile hydrating activity of the nitrile hydratase is improved depending on the contact time, and simultaneously the improved activity is maintained.", "Example 14 A wet microorganism was obtained in the same manner as in Example 3.", "The resulting wet microorganism, 1.5 g, was suspended in 48.5 g pure water in a 100 mL flask equipped with an oxygen electrode and a thermometer.", "The suspension was kept at 10° C. under stirring, while the air (40 N-ml/min.) was passed through the gaseous phase in the flask.", "0, 1, 2, 3, 7 and 19 days after storage, a part of the microbial suspension was removed.", "During this storage, the concentration of dissolved oxygen in the microbial suspension indicated 10.0 to 10.9 ppm.", "The amount of formed acrylamide in each of the collected microbial suspensions per unit dry weight of the microorganism was determined in the same manner as in Example 3.", "Assuming that the amount of acrylamide formed on 0 day of storage by per unit dry weight of the microorganism is 1, the amounts of acrylamide formed on the first day, second day, third day, seventh day and nineteenth day of storage are shown as relative values in Table 3.", "Example 15 A wet microorganism was obtained in the same manner as in Example 3.", "The resulting wet microorganism, 1.5 g, was suspended in 48.5 g pure water in a 100 mL flask equipped with an oxygen electrode and a thermometer.", "The suspension was kept at 10° C. under stirring, while a mixture of the air (40 N-ml/min.) and nitrogen (400 N-ml/min.) was passed through the gaseous phase in the flask.", "0, 1, 2, 3, 7 and 19 days after storage, a part of the microbial suspension was removed.", "During this storage, the concentration of dissolved oxygen in the microbial suspension indicated 1.0 to 1.5 ppm.", "The amount of formed acrylamide in each of the collected microbial suspensions per unit dry weight of the microorganism was determined in the same manner as in Example 3.", "Assuming that the amount of acrylamide formed on 0 day of storage by per unit dry weight of the microorganism is 1, the amounts of acrylamide formed on the first day, second day, third day, seventh day and nineteenth day of storage are shown as relative values in Table 3.", "TABLE 3 NUMBER OF DAYS FOR STORAGE 0 1 2 3 7 19 EXAMPLE 14 1.0 2.4 2.3 2.4 2.5 2.5 EXAMPLE 15 1.0 1.6 2.3 2.4 2.5 2.4 From the results shown above, it can be seen that when the microorganism is brought into contact with oxygen as the oxidizing agent, the nitrile hydrating activity of the nitrile hydratase is improved depending on the contact time, and after a predetermined time, the nitrile hydrating activity is highly and stably maintained.", "Examples 16 to 18 0.20 g wet microorganism obtained in the same manner as in Example 3 was suspended in previously deoxidized pure water in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and potassium ferricyanide was added and suspended as an oxidizing agent at a final concentration of 2.0% by weight, and the suspension was adjusted with an aqueous sodium hydroxide solution or sulfuric acid to a pH value shown in Table 4 to give 20.00 g suspension.", "Separately, a microbial suspension wherein the oxidizing agent was not added and the pH value was not adjusted was also prepared in the same manner.", "The microbial suspension was kept at 20° C. for 15 minutes under stirring.", "The amount of formed acrylamide per unit dry weight of the microorganism was determined in the same manner as in Example 3.", "Assuming that the amount of acrylamide formed per unit dry weight of the microorganism in the case where the oxidizing agent was not added and the pH value was not regulated is 1, the amounts of acrylamide formed in Examples 16 to 18 are shown as relative values in Table 4.", "TABLE 4 AMOUNT OF ACRYLAMIDE BUFFER FORMED (REL- REAGENT SOLUTION PH ATIVE VALUE) — NOT ADDED NOT 1.0 REGULATED (7.1) EXAMPLE 16 POTASSIUM 5.0 1.8 FERRICYANIDE EXAMPLE 17 POTASSIUM 6.7 2.9 FERRICYANIDE EXAMPLE 18 POTASSIUM 10.0 2.0 FERRICYANIDE Examples 19 to 21 0.20 g wet microorganism obtained in the same manner as in Example 3 was suspended in previously deoxidized pure water in a 100 ml sealable glass container previously sufficiently purged with nitrogen, and potassium ferricyanide was added and suspended as an oxidizing agent at a final concentration of 2.0% by weight to give 20.00 g suspension.", "Separately, a microbial suspension wherein the oxidizing agent was not added was also prepared in the same manner.", "The microbial suspension was stirred for 15 minutes at a temperature shown in Table 6.", "The amount of formed acrylamide per unit dry weight of the microorganism was determined in the same manner as in Example 3.", "Assuming that the amount of acrylamide formed per unit dry weight of the microorganism in the suspension stirred at a temperature of 20° C. in the absence of the oxidizing agent is 1, the amounts of acrylamide formed in Examples 19 to 21 are shown as relative values in Table 5.", "TABLE 5 TEMPERATURE AMOUNT OF OF THE ACRYLAMIDE SUSPENSION FORMED (REL- REAGENT (° C.) ATIVE VALUE) — NOT ADDED 20 1.0 EXAMPLE 19 POTASSIUM 0 3.2 FERRICYANIDE EXAMPLE 20 POTASSIUM 20 2.9 FERRICYANIDE EXAMPLE 21 POTASSIUM 60 1.4 FERRICYANIDE The present invention can not only easily maintain the nitrile hydratase activity of a nitrile hydratase-containing cell or a treated material of the cell under conditions where the cell does not grow, but also improve the nitrile hydratase activity of a nitrile hydratase-containing cell whose activity was once reduced or a treated material of the cell, and thus the present invention is industrially advantageous." ]
CROSS REFERENCE TO RELATED APPLICATION The present application is related to PCT patent application Ser. No. PCT/JP2008/060680 titled “Torque Control Device, And Its Control Method”, and to Japanese Patent application no. 2007-167864 filed at Japan Patent Office titled “Torque Control Device, And Its Control Method”, all of which are incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque control device applied to, for example, a screw tightening device and a method for controlling the same, the torque control device tightening connecting members by application of torsional torque. 2. Description of Related Art It is an object of a known art, for example, Japanese Unexamined Patent Application Publication No. 10-080872, to reduce the overshoot of tightening torque. A current limiting unit monitors the value of current supplied from a current amplifier to a motor and performs interrupt control of a current reference unit so that the value of current does not exceed a current limit value input to the current limiting unit from a general reference unit. The current limit value in the current limiting unit is determined by iL(t)=iT·exp{−v(t)/K}, where iL(t) is the current limit value at a time t, iT is the value of current for producing target torque, v(t) is motor rotational speed at the time t, and K is a constant. The current limit value increases and decreases in response to the motor rotational speed. As a predetermined value of driving current corresponding to the target tightening torque is approached, the value of the driving current gradually increases, and thus the tightening torque also gradually increases, so that the tightening torque gradually reaches the target tightening torque without exceeding the target tightening torque. That is, a screw member is appropriately tightened with predetermined torque without the overshoot of the rotational torque of a motor. Thus, the overshoot of tightening torque can be reduced. Moreover, for example, it is an object of Japanese Unexamined Patent Application Publication No. 6-182638 to improve the accuracy of screw tightening torque by preventing an actual torque value from being irregular, for example, sharply increasing, due to a change in friction between a screw and a workpiece, lost motion in a mechanical transmission system such as a motor shaft and a speed reducer, and the like. A torque sensor that detects rotational torque is provided. The detected torque value is fed back, and a torque reference is output to a current driven driver so as to perform control so that motor rotational torque reaches a set torque value, and when the detected torque value reaches a target torque value, a current reference from the current driven driver is turned off to stop a motor. SUMMARY OF THE INVENTION A torque control device according to a first aspect of the present invention that controls torque of a first mechanical unit and a second mechanical unit connected coaxially to each other through connecting members is provided. The torque control device includes a controller that generates a first reference and a second reference on the basis of a command from a host system, a first motor that drives the first mechanical unit, a second motor that drives the second mechanical unit, a first motor control unit that controls the first motor on the basis of the first reference, and a second motor control unit that controls the second motor on the basis of the second reference. The first reference and the second reference synchronously accelerate the first motor and the second motor until first rotational speed is reached, then change rotational speed of the second motor according to a predetermined speed profile in which the rotational speed of the second motor is higher than the first rotational speed to produce torsional torque in the connecting members, decelerate the second motor to the first rotational speed after the torsional torque reaches a predetermined value, and synchronously decelerate and stop the first motor and the second motor after a predetermined time period elapses. A torque control device according to a second aspect of the present invention that controls torque of a first mechanical unit and a second mechanical unit connected coaxially to each other through connecting members is provided. The torque control device includes a controller that generates a first reference and a second reference on the basis of a command from a host system, a first motor that drives the first mechanical unit, a second motor that drives the second mechanical unit, a first motor control unit that controls the first motor on the basis of the first reference, and a second motor control unit that controls the second motor on the basis of the second reference. The first reference and the second reference synchronously accelerate the first motor and the second motor until first rotational speed is reached, then increase rotational speed of the second motor to second rotational speed that is higher than the first rotational speed to produce torsional torque in the connecting members, decelerate the second motor to third rotational speed that is equal to or more than the first rotational speed and less than the second rotational speed after the torsional torque reaches first torque, decelerate the second motor to fourth rotational speed that is equal to or more than the first rotational speed and less than the third rotational speed after the torsional torque reaches second torque, decelerate the second motor to the first rotational speed after the torsional torque reaches third torque, and synchronously decelerate and stop the first motor and the second motor after a predetermined time period elapses. A torque control device according to a third aspect of the present invention that controls torque of a first mechanical unit and a second mechanical unit connected coaxially to each other through connecting members is provided. The torque control device includes a controller that generates a first reference and a second reference on the basis of a command from a host system, a first motor that drives the first mechanical unit, a second motor that drives the second mechanical unit, a first motor control unit that controls the first motor on the basis of the first reference, and a second motor control unit that controls the second motor on the basis of the second reference. The first reference and the second reference synchronously accelerate the first motor and the second motor until first rotational speed is reached, then produce torsional torque by changing motor phase difference between the first motor and the second motor according to a predetermined profile by increasing rotational speed of the second motor, change the motor phase difference according to the predetermined profile after the torsional torque reaches first torque, fix the motor phase difference after the torsional torque reaches third torque, and synchronously decelerate and stop the first motor and the second motor after a predetermined time period elapses. BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: FIG. 1 is a block diagram showing a configuration of a torque control device according to the present invention; FIG. 2 is a block diagram showing a configuration of each of a first motor control unit and a second motor control unit in the torque control device according to the present invention; FIG. 3 is a time chart showing the speed profile of a position reference in the torque control device according to the present invention; FIG. 4 is a simulation block diagram; FIG. 5 is a simulation control block diagram; FIG. 6 shows the result of a simulation; and FIG. 7 is a block diagram showing another configuration of the torque control device according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a torque control device according to the present invention. The torque control device according to the present invention includes a common power supply 1 , a controller 2 , a first motor control unit 3 , a second motor control unit 4 , a first motor 5 , a second motor 6 , a first mechanical unit 7 , a second mechanical unit 8 , and connecting members 9 . The controller 2 generates a first reference and a second reference by executing stored programs according to a command from a host system. The first motor control unit 3 controls the first motor 5 according to the first reference. The second motor control unit 4 controls the second motor 6 according to the second reference. The first motor 5 drives the first mechanical unit 7 . The second motor 6 drives the second mechanical unit 8 . The connecting members 9 connect the first mechanical unit 7 to the second mechanical unit 8 . The common power supply 1 generates direct-current power by rectifying three-phase alternating-current power to supply electrical power to the first motor control unit 3 and the second motor control unit 4 . Moreover, the controller 2 includes a reference generation unit, a first communication unit, a second communication unit, and programs. The first communication unit receives a command from the host system and sends a response. The reference generation unit generates the first reference for the first motor control unit 3 and the second reference for the second motor control unit 4 on the basis of the stored programs and the command from the host system. The second communication unit converts the first and second references to commands to send the commands to the first motor control unit 3 and the second motor control unit 4 and receives a response from each of the first motor control unit 3 and the second motor control unit 4 . Each of the first and second references generates a control mode reference that defines which of position control, speed control, and torque control a corresponding one of the first motor control unit 3 and the second motor control unit 4 performs, a position reference, an external speed reference, and an external torque reference. FIG. 2 is a block diagram showing a configuration of each of the first motor control unit 3 and the second motor control unit 4 in the torque control device according to the present invention. Each of the first motor control unit 3 and the second motor control unit 4 includes a position control unit 31 , a speed reference add unit 32 , a speed control unit 33 , a torque reference add unit 34 , a current reference generation unit 35 , a current control unit 36 , an electrical power conversion unit 37 , a speed signal generation unit 38 , and a communication unit 39 . Moreover, the first motor control unit 3 and the second motor control unit 4 drive a motor 51 that includes a position detector 52 . The communication unit 39 receives, using serial communication, a command generated by the controller 2 and sends the status of the motor control unit as a response. Position control, speed control, or torque control is selected on the basis of the control mode reference of the command. When position control is defined, the position control unit 31 generates a speed reference by performing a proportional-integral-derivative (PID) control operation on position variation that is the difference between the position reference and a position signal. The speed reference add unit 32 generates a new speed reference by adding the speed reference to the external speed reference. The speed control unit 33 generates a torque reference by performing a PID control operation on speed variation that is the difference between the speed reference and a speed signal. The torque reference add unit 34 generates a new torque reference by adding the torque reference to the external torque reference. The current reference unit 35 generates a current reference by dividing the torque reference by the torque constant of the motor 51 . The current control unit 36 generates a voltage reference by performing a PID control operation on current variation that is the difference between the current reference and a current signal. The electrical power conversion unit 37 generates a pulse-width modulation (PWM) signal from the voltage reference to drive an inverter (not shown). The inverter generates modulated voltage from direct-current voltage supplied from the common power supply 1 , using the PWM signal, and applies the modulated voltage to the motor 51 . The position detector 52 generates a position signal of the motor 51 . The speed signal generation unit 38 generates a speed signal by obtaining the time difference of a position signal. FIG. 3 is a time chart showing the speed profile of a position reference in the torque control device according to the present invention. The control mode is the position control mode. In this time chart, in order to improve the accuracy of tightening torque by eliminating the influence of static friction torque in a state in which a nut and a bolt are rotated and tightening the bolt and the nut against each other with low relative rotational speed difference between the nut and the bolt, several revolutions per minute, the nut and the bolt in a state in which the bolt is screwed into the nut are first synchronously accelerated to predetermined rotational speed. Subsequently, when the predetermined rotational speed is reached, the rotational speed of the nut or the bolt is increased to predetermined rotational speed to produce tightening torque between the nut and the bolt. Subsequently, when the tightening torque reaches a predetermined value, the higher rotational speed is reduced in response to the torque to be synchronized with the initial rotational speed. Then, after a predetermined time period elapses, the rotational speed is reduced, so that the rotation is stopped. Assuming that first rotational speed time is t, the first and second references accelerate the rotation to first rotational speed with acceleration α. When the first rotational speed is reached at a time t 1 , the first rotational speed is kept until a time t 2 . At the time t 2 , only the second reference accelerates the rotation to second rotational speed with acceleration α. When the second rotational speed is reached at a time t 3 , the second rotational speed is kept. When the torque reference reaches first torque at a time t 4 , the rotation is decelerated to third rotational speed with deceleration β. When the third rotational speed is reached at a time t 5 , the third rotational speed is kept. When the torque reference reaches second torque at a time t 6 , the rotation is decelerated to fourth rotational speed with the deceleration β. When the fourth rotational speed is reached at a time t 7 , the fourth rotational speed is kept. When the torque reference reaches third torque at a time t 8 , the rotation is decelerated to the first rotational speed with the deceleration β. When the first rotational speed is reached at a time t 9 , the first rotational speed is kept. After a predetermined time period elapses, the rotation is decelerated to be stopped. In this case, since torsional torque is almost proportional to the phase difference between the first motor 5 and the second motor 6 , instead of the speed profile, the profile of the phase difference between the first motor 5 and the second motor 6 may be used. For example, the first motor 5 and the second motor 6 are first synchronously accelerated. When the first rotational speed is reached, torsional torque is produced by changing the phase difference between the first motor 5 and the second motor 6 according to a predetermined profile by setting the rotational speed of the second motor 6 higher than the first rotational speed. Subsequently, when the torsional torque reaches the first torque, the phase difference between the first motor 5 and the second motor 6 is changed according to the predetermined profile. Subsequently, when the third torque is reached, the phase difference between the first motor 5 and the second motor 6 is fixed. After a predetermined time period elapses, the respective rotational speeds of the first motor 5 and the second motor 6 are synchronized with each other and then reduced, so that the first motor 5 and the second motor 6 are stopped. A result of a simulation in the torque control device according to the present invention will next be described. FIG. 4 is a simulation block diagram. FIG. 5 is a simulation control block diagram. FIG. 6 shows the result of the simulation. Members that have a tightening torque of zero until an angle θ and have spring properties when the angle θ is exceeded are used as the connecting members 9 . Moreover, it is assumed that the moment of inertia on the first motor 5 side is J 1 , the moment of inertia on the second motor 6 side is J 2 , and the spring constant of a connecting portion is Ks. The conditions of the simulation are as follows: the position control gain Kp=200 (s −1 ), the speed control proportional gain Kv=1 (Nms/r), and the speed control integral time constant Tvi=10 (ms) for each of the first motor control unit 3 and the second motor control unit 4 , the first-motor-side moment-of-inertia J 1 =0.001 (kgm 2 ), the second-motor-side moment-of-inertia J 2 =0.001 (kgm 2 ), and the connecting portion spring constant Ks=10 (Nm/r). The speed profile is as follows: the first rotational speed N 1 =1260 (rpm), the second rotational speed N 2 =1386 (rpm), the third rotational speed N 3 =1283 (rpm), the fourth rotational speed N 4 =1268 (rpm), and the angular accelerations α=1320 (rad/s 2 ) and β=−1320 (rad/s 2 ). The first torque Tq 1 =11 (Nm), the second torque Tq 2 =14 (Nm), and the third torque Tq 3 =15 (Nm) are given. As is clear from the result of the simulation in FIG. 6 , the first motor 5 produces braking torque in reaction to torque produced by the second motor 6 and functions as an electric generator. In this case, in order to cancel driving power and generated power, direct-current power supplied to the inverter of the electrical power conversion unit 37 is common. The detection of torsional torque will next be described. The controller 2 receives torque references from the first motor control unit 3 and the second motor control unit 4 as response information at each control time. Thus, the inversion value of the torque reference of the first motor control unit 3 (for example, when the torque reference of the first motor control unit 3 is a negative torque reference, the inversion value represents a positive torque reference) or the torque reference of the second motor control unit 4 may be used as detected torsional torque. Moreover, when the moment of inertia of the first motor 5 and the first mechanical unit 7 is substantially the same as the moment of inertia of the second motor 6 and the second mechanical unit 8 , the respective torques of the first motor 5 and the second motor 6 during acceleration and deceleration are offset against each other by using a value obtained by subtracting the torque reference of the first motor control unit 3 from the torque reference of the second motor control unit 4 and then dividing the result by two, and thus torsional torque can be detected. The detected torsional torque in FIG. 6 has a value obtained by subtracting the torque reference of the first motor control unit 3 from the torque reference of the second motor control unit 4 and then dividing the result by two. When further accurate torsional torque needs to be detected, a non-contact torque sensor may be provided in the first mechanical unit 7 or the second mechanical unit 8 to directly detect torsional torque. FIG. 7 is a block diagram showing another configuration of the torque control device according to the present invention. This is an example in which a non-contact torque sensor 10 and a non-contact torque sensor 11 are respectively provided in the first mechanical unit 7 and the second mechanical unit 8 . The first motor control unit 3 or the second motor control unit 4 receives a torsional torque signal and sends the torsional torque signal to the controller 2 . Methods according to the present invention for controlling a torque control device will next be described. A method according to the present invention for controlling a torque control device performs processing in the following steps: the first motor 5 and the second motor 6 are synchronously accelerated (step 1 ), when the first rotational speed is reached, the rotational speed of the second motor 6 is changed according to a predetermined speed profile in which the rotational speed of the second motor 6 is higher than the first rotational speed to produce torsional torque in the connecting members 9 (step 2 ), when the torsional torque reaches a predetermined value, the second motor 6 is decelerated to the first rotational speed (step 3 ), and after a predetermined time period elapses, the first motor 5 and the second motor 6 are synchronously decelerated to be stopped (step 4 ). Moreover, another method according to the present invention for controlling a torque control device performs processing in the following steps: the first motor 5 and the second motor 6 are synchronously accelerated (step 10 ), when the first rotational speed is reached, the rotational speed of the second motor 6 is increased to the second rotational speed, which is higher than the first rotational speed, to produce torsional torque (step 11 ), when the torsional torque reaches the first torque, the second motor 6 is decelerated to the third rotational speed where the first rotational speed<the third rotational speed<the second rotational speed (step 12 ), when the torsional torque reaches the second torque, the second motor 6 is decelerated to the fourth rotational speed where the first rotational speed<the fourth rotational speed<the third rotational speed (step 13 ), when the torsional torque reaches the third torque, the second motor 6 is decelerated to the first rotational speed (step 14 ), and after a predetermined time period elapses, the first motor 5 and the second motor 6 are synchronously decelerated to be stopped (step 15 ). The torque control device and the methods for controlling the same according to the present invention can control torque even when a motor is rotating and thus can be applied to not only a screw tightening device but also a testing device, such as a motor testing device, a machine testing device, or a simulated load device. Moreover, the torque control device according to the present invention can perform highly accurate control of torsional torque by eliminating the influence of static friction torque and setting relative rotational speed difference between connecting members to low speed, several revolutions per minute.
A torque control device controlling torque of first and second mechanical units connected coaxially to each other through connecting members includes a controller generating first and second references from a command from a host system, first and second motors respectively driving the first and second mechanical units, first and second motor control units respectively controlling the first and second motors on the basis of the first and second references. The first and second references synchronously accelerate the first and second motors to first rotational speed, then increase rotational speed of the second motor according to a speed profile to produce torsional torque in the connecting members, decelerate the second motor to the first rotational speed after the torsional torque reaches a predetermined value, and synchronously decelerate and stop the first and second motors after a predetermined time period elapses.
Identify the most important claim in the given context and summarize it
[ "CROSS REFERENCE TO RELATED APPLICATION The present application is related to PCT patent application Ser.", "No. PCT/JP2008/060680 titled “Torque Control Device, And Its Control Method”, and to Japanese Patent application no. 2007-167864 filed at Japan Patent Office titled “Torque Control Device, And Its Control Method”, all of which are incorporated herein by reference.", "BACKGROUND OF THE INVENTION 1.", "Field of the Invention The present invention relates to a torque control device applied to, for example, a screw tightening device and a method for controlling the same, the torque control device tightening connecting members by application of torsional torque.", "Description of Related Art It is an object of a known art, for example, Japanese Unexamined Patent Application Publication No. 10-080872, to reduce the overshoot of tightening torque.", "A current limiting unit monitors the value of current supplied from a current amplifier to a motor and performs interrupt control of a current reference unit so that the value of current does not exceed a current limit value input to the current limiting unit from a general reference unit.", "The current limit value in the current limiting unit is determined by iL(t)=iT·exp{−v(t)/K}, where iL(t) is the current limit value at a time t, iT is the value of current for producing target torque, v(t) is motor rotational speed at the time t, and K is a constant.", "The current limit value increases and decreases in response to the motor rotational speed.", "As a predetermined value of driving current corresponding to the target tightening torque is approached, the value of the driving current gradually increases, and thus the tightening torque also gradually increases, so that the tightening torque gradually reaches the target tightening torque without exceeding the target tightening torque.", "That is, a screw member is appropriately tightened with predetermined torque without the overshoot of the rotational torque of a motor.", "Thus, the overshoot of tightening torque can be reduced.", "Moreover, for example, it is an object of Japanese Unexamined Patent Application Publication No. 6-182638 to improve the accuracy of screw tightening torque by preventing an actual torque value from being irregular, for example, sharply increasing, due to a change in friction between a screw and a workpiece, lost motion in a mechanical transmission system such as a motor shaft and a speed reducer, and the like.", "A torque sensor that detects rotational torque is provided.", "The detected torque value is fed back, and a torque reference is output to a current driven driver so as to perform control so that motor rotational torque reaches a set torque value, and when the detected torque value reaches a target torque value, a current reference from the current driven driver is turned off to stop a motor.", "SUMMARY OF THE INVENTION A torque control device according to a first aspect of the present invention that controls torque of a first mechanical unit and a second mechanical unit connected coaxially to each other through connecting members is provided.", "The torque control device includes a controller that generates a first reference and a second reference on the basis of a command from a host system, a first motor that drives the first mechanical unit, a second motor that drives the second mechanical unit, a first motor control unit that controls the first motor on the basis of the first reference, and a second motor control unit that controls the second motor on the basis of the second reference.", "The first reference and the second reference synchronously accelerate the first motor and the second motor until first rotational speed is reached, then change rotational speed of the second motor according to a predetermined speed profile in which the rotational speed of the second motor is higher than the first rotational speed to produce torsional torque in the connecting members, decelerate the second motor to the first rotational speed after the torsional torque reaches a predetermined value, and synchronously decelerate and stop the first motor and the second motor after a predetermined time period elapses.", "A torque control device according to a second aspect of the present invention that controls torque of a first mechanical unit and a second mechanical unit connected coaxially to each other through connecting members is provided.", "The torque control device includes a controller that generates a first reference and a second reference on the basis of a command from a host system, a first motor that drives the first mechanical unit, a second motor that drives the second mechanical unit, a first motor control unit that controls the first motor on the basis of the first reference, and a second motor control unit that controls the second motor on the basis of the second reference.", "The first reference and the second reference synchronously accelerate the first motor and the second motor until first rotational speed is reached, then increase rotational speed of the second motor to second rotational speed that is higher than the first rotational speed to produce torsional torque in the connecting members, decelerate the second motor to third rotational speed that is equal to or more than the first rotational speed and less than the second rotational speed after the torsional torque reaches first torque, decelerate the second motor to fourth rotational speed that is equal to or more than the first rotational speed and less than the third rotational speed after the torsional torque reaches second torque, decelerate the second motor to the first rotational speed after the torsional torque reaches third torque, and synchronously decelerate and stop the first motor and the second motor after a predetermined time period elapses.", "A torque control device according to a third aspect of the present invention that controls torque of a first mechanical unit and a second mechanical unit connected coaxially to each other through connecting members is provided.", "The torque control device includes a controller that generates a first reference and a second reference on the basis of a command from a host system, a first motor that drives the first mechanical unit, a second motor that drives the second mechanical unit, a first motor control unit that controls the first motor on the basis of the first reference, and a second motor control unit that controls the second motor on the basis of the second reference.", "The first reference and the second reference synchronously accelerate the first motor and the second motor until first rotational speed is reached, then produce torsional torque by changing motor phase difference between the first motor and the second motor according to a predetermined profile by increasing rotational speed of the second motor, change the motor phase difference according to the predetermined profile after the torsional torque reaches first torque, fix the motor phase difference after the torsional torque reaches third torque, and synchronously decelerate and stop the first motor and the second motor after a predetermined time period elapses.", "BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: FIG. 1 is a block diagram showing a configuration of a torque control device according to the present invention;", "FIG. 2 is a block diagram showing a configuration of each of a first motor control unit and a second motor control unit in the torque control device according to the present invention;", "FIG. 3 is a time chart showing the speed profile of a position reference in the torque control device according to the present invention;", "FIG. 4 is a simulation block diagram;", "FIG. 5 is a simulation control block diagram;", "FIG. 6 shows the result of a simulation;", "and FIG. 7 is a block diagram showing another configuration of the torque control device according to the present invention.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described with reference to the drawings.", "FIG. 1 is a block diagram showing a configuration of a torque control device according to the present invention.", "The torque control device according to the present invention includes a common power supply 1 , a controller 2 , a first motor control unit 3 , a second motor control unit 4 , a first motor 5 , a second motor 6 , a first mechanical unit 7 , a second mechanical unit 8 , and connecting members 9 .", "The controller 2 generates a first reference and a second reference by executing stored programs according to a command from a host system.", "The first motor control unit 3 controls the first motor 5 according to the first reference.", "The second motor control unit 4 controls the second motor 6 according to the second reference.", "The first motor 5 drives the first mechanical unit 7 .", "The second motor 6 drives the second mechanical unit 8 .", "The connecting members 9 connect the first mechanical unit 7 to the second mechanical unit 8 .", "The common power supply 1 generates direct-current power by rectifying three-phase alternating-current power to supply electrical power to the first motor control unit 3 and the second motor control unit 4 .", "Moreover, the controller 2 includes a reference generation unit, a first communication unit, a second communication unit, and programs.", "The first communication unit receives a command from the host system and sends a response.", "The reference generation unit generates the first reference for the first motor control unit 3 and the second reference for the second motor control unit 4 on the basis of the stored programs and the command from the host system.", "The second communication unit converts the first and second references to commands to send the commands to the first motor control unit 3 and the second motor control unit 4 and receives a response from each of the first motor control unit 3 and the second motor control unit 4 .", "Each of the first and second references generates a control mode reference that defines which of position control, speed control, and torque control a corresponding one of the first motor control unit 3 and the second motor control unit 4 performs, a position reference, an external speed reference, and an external torque reference.", "FIG. 2 is a block diagram showing a configuration of each of the first motor control unit 3 and the second motor control unit 4 in the torque control device according to the present invention.", "Each of the first motor control unit 3 and the second motor control unit 4 includes a position control unit 31 , a speed reference add unit 32 , a speed control unit 33 , a torque reference add unit 34 , a current reference generation unit 35 , a current control unit 36 , an electrical power conversion unit 37 , a speed signal generation unit 38 , and a communication unit 39 .", "Moreover, the first motor control unit 3 and the second motor control unit 4 drive a motor 51 that includes a position detector 52 .", "The communication unit 39 receives, using serial communication, a command generated by the controller 2 and sends the status of the motor control unit as a response.", "Position control, speed control, or torque control is selected on the basis of the control mode reference of the command.", "When position control is defined, the position control unit 31 generates a speed reference by performing a proportional-integral-derivative (PID) control operation on position variation that is the difference between the position reference and a position signal.", "The speed reference add unit 32 generates a new speed reference by adding the speed reference to the external speed reference.", "The speed control unit 33 generates a torque reference by performing a PID control operation on speed variation that is the difference between the speed reference and a speed signal.", "The torque reference add unit 34 generates a new torque reference by adding the torque reference to the external torque reference.", "The current reference unit 35 generates a current reference by dividing the torque reference by the torque constant of the motor 51 .", "The current control unit 36 generates a voltage reference by performing a PID control operation on current variation that is the difference between the current reference and a current signal.", "The electrical power conversion unit 37 generates a pulse-width modulation (PWM) signal from the voltage reference to drive an inverter (not shown).", "The inverter generates modulated voltage from direct-current voltage supplied from the common power supply 1 , using the PWM signal, and applies the modulated voltage to the motor 51 .", "The position detector 52 generates a position signal of the motor 51 .", "The speed signal generation unit 38 generates a speed signal by obtaining the time difference of a position signal.", "FIG. 3 is a time chart showing the speed profile of a position reference in the torque control device according to the present invention.", "The control mode is the position control mode.", "In this time chart, in order to improve the accuracy of tightening torque by eliminating the influence of static friction torque in a state in which a nut and a bolt are rotated and tightening the bolt and the nut against each other with low relative rotational speed difference between the nut and the bolt, several revolutions per minute, the nut and the bolt in a state in which the bolt is screwed into the nut are first synchronously accelerated to predetermined rotational speed.", "Subsequently, when the predetermined rotational speed is reached, the rotational speed of the nut or the bolt is increased to predetermined rotational speed to produce tightening torque between the nut and the bolt.", "Subsequently, when the tightening torque reaches a predetermined value, the higher rotational speed is reduced in response to the torque to be synchronized with the initial rotational speed.", "Then, after a predetermined time period elapses, the rotational speed is reduced, so that the rotation is stopped.", "Assuming that first rotational speed time is t, the first and second references accelerate the rotation to first rotational speed with acceleration α.", "When the first rotational speed is reached at a time t 1 , the first rotational speed is kept until a time t 2 .", "At the time t 2 , only the second reference accelerates the rotation to second rotational speed with acceleration α.", "When the second rotational speed is reached at a time t 3 , the second rotational speed is kept.", "When the torque reference reaches first torque at a time t 4 , the rotation is decelerated to third rotational speed with deceleration β.", "When the third rotational speed is reached at a time t 5 , the third rotational speed is kept.", "When the torque reference reaches second torque at a time t 6 , the rotation is decelerated to fourth rotational speed with the deceleration β.", "When the fourth rotational speed is reached at a time t 7 , the fourth rotational speed is kept.", "When the torque reference reaches third torque at a time t 8 , the rotation is decelerated to the first rotational speed with the deceleration β.", "When the first rotational speed is reached at a time t 9 , the first rotational speed is kept.", "After a predetermined time period elapses, the rotation is decelerated to be stopped.", "In this case, since torsional torque is almost proportional to the phase difference between the first motor 5 and the second motor 6 , instead of the speed profile, the profile of the phase difference between the first motor 5 and the second motor 6 may be used.", "For example, the first motor 5 and the second motor 6 are first synchronously accelerated.", "When the first rotational speed is reached, torsional torque is produced by changing the phase difference between the first motor 5 and the second motor 6 according to a predetermined profile by setting the rotational speed of the second motor 6 higher than the first rotational speed.", "Subsequently, when the torsional torque reaches the first torque, the phase difference between the first motor 5 and the second motor 6 is changed according to the predetermined profile.", "Subsequently, when the third torque is reached, the phase difference between the first motor 5 and the second motor 6 is fixed.", "After a predetermined time period elapses, the respective rotational speeds of the first motor 5 and the second motor 6 are synchronized with each other and then reduced, so that the first motor 5 and the second motor 6 are stopped.", "A result of a simulation in the torque control device according to the present invention will next be described.", "FIG. 4 is a simulation block diagram.", "FIG. 5 is a simulation control block diagram.", "FIG. 6 shows the result of the simulation.", "Members that have a tightening torque of zero until an angle θ and have spring properties when the angle θ is exceeded are used as the connecting members 9 .", "Moreover, it is assumed that the moment of inertia on the first motor 5 side is J 1 , the moment of inertia on the second motor 6 side is J 2 , and the spring constant of a connecting portion is Ks.", "The conditions of the simulation are as follows: the position control gain Kp=200 (s −1 ), the speed control proportional gain Kv=1 (Nms/r), and the speed control integral time constant Tvi=10 (ms) for each of the first motor control unit 3 and the second motor control unit 4 , the first-motor-side moment-of-inertia J 1 =0.001 (kgm 2 ), the second-motor-side moment-of-inertia J 2 =0.001 (kgm 2 ), and the connecting portion spring constant Ks=10 (Nm/r).", "The speed profile is as follows: the first rotational speed N 1 =1260 (rpm), the second rotational speed N 2 =1386 (rpm), the third rotational speed N 3 =1283 (rpm), the fourth rotational speed N 4 =1268 (rpm), and the angular accelerations α=1320 (rad/s 2 ) and β=−1320 (rad/s 2 ).", "The first torque Tq 1 =11 (Nm), the second torque Tq 2 =14 (Nm), and the third torque Tq 3 =15 (Nm) are given.", "As is clear from the result of the simulation in FIG. 6 , the first motor 5 produces braking torque in reaction to torque produced by the second motor 6 and functions as an electric generator.", "In this case, in order to cancel driving power and generated power, direct-current power supplied to the inverter of the electrical power conversion unit 37 is common.", "The detection of torsional torque will next be described.", "The controller 2 receives torque references from the first motor control unit 3 and the second motor control unit 4 as response information at each control time.", "Thus, the inversion value of the torque reference of the first motor control unit 3 (for example, when the torque reference of the first motor control unit 3 is a negative torque reference, the inversion value represents a positive torque reference) or the torque reference of the second motor control unit 4 may be used as detected torsional torque.", "Moreover, when the moment of inertia of the first motor 5 and the first mechanical unit 7 is substantially the same as the moment of inertia of the second motor 6 and the second mechanical unit 8 , the respective torques of the first motor 5 and the second motor 6 during acceleration and deceleration are offset against each other by using a value obtained by subtracting the torque reference of the first motor control unit 3 from the torque reference of the second motor control unit 4 and then dividing the result by two, and thus torsional torque can be detected.", "The detected torsional torque in FIG. 6 has a value obtained by subtracting the torque reference of the first motor control unit 3 from the torque reference of the second motor control unit 4 and then dividing the result by two.", "When further accurate torsional torque needs to be detected, a non-contact torque sensor may be provided in the first mechanical unit 7 or the second mechanical unit 8 to directly detect torsional torque.", "FIG. 7 is a block diagram showing another configuration of the torque control device according to the present invention.", "This is an example in which a non-contact torque sensor 10 and a non-contact torque sensor 11 are respectively provided in the first mechanical unit 7 and the second mechanical unit 8 .", "The first motor control unit 3 or the second motor control unit 4 receives a torsional torque signal and sends the torsional torque signal to the controller 2 .", "Methods according to the present invention for controlling a torque control device will next be described.", "A method according to the present invention for controlling a torque control device performs processing in the following steps: the first motor 5 and the second motor 6 are synchronously accelerated (step 1 ), when the first rotational speed is reached, the rotational speed of the second motor 6 is changed according to a predetermined speed profile in which the rotational speed of the second motor 6 is higher than the first rotational speed to produce torsional torque in the connecting members 9 (step 2 ), when the torsional torque reaches a predetermined value, the second motor 6 is decelerated to the first rotational speed (step 3 ), and after a predetermined time period elapses, the first motor 5 and the second motor 6 are synchronously decelerated to be stopped (step 4 ).", "Moreover, another method according to the present invention for controlling a torque control device performs processing in the following steps: the first motor 5 and the second motor 6 are synchronously accelerated (step 10 ), when the first rotational speed is reached, the rotational speed of the second motor 6 is increased to the second rotational speed, which is higher than the first rotational speed, to produce torsional torque (step 11 ), when the torsional torque reaches the first torque, the second motor 6 is decelerated to the third rotational speed where the first rotational speed<the third rotational speed<the second rotational speed (step 12 ), when the torsional torque reaches the second torque, the second motor 6 is decelerated to the fourth rotational speed where the first rotational speed<the fourth rotational speed<the third rotational speed (step 13 ), when the torsional torque reaches the third torque, the second motor 6 is decelerated to the first rotational speed (step 14 ), and after a predetermined time period elapses, the first motor 5 and the second motor 6 are synchronously decelerated to be stopped (step 15 ).", "The torque control device and the methods for controlling the same according to the present invention can control torque even when a motor is rotating and thus can be applied to not only a screw tightening device but also a testing device, such as a motor testing device, a machine testing device, or a simulated load device.", "Moreover, the torque control device according to the present invention can perform highly accurate control of torsional torque by eliminating the influence of static friction torque and setting relative rotational speed difference between connecting members to low speed, several revolutions per minute." ]
BACKGROUND OF THE INVENTION This invention relates to a system for locating a vehicle and guiding it along its route, in which the vehicle's position in an area represented by a digitized map database is continuously determined. Since navigation and route guidance decisions are based on this continuously-determined position, it is necessary that the position be determined accurately. In known vehicle navigation systems, a vehicle's position is continuously determined in relative or absolute X-Y coordinates. This position determination is absolute, if determined, for example, by GPS (Global Positioning System) or Loran C, or relative, if determined by dead reckoning through the continuous integration of successive displacement vectors. However, the position so determined in either case is not always accurate. Because of errors in sensing and computation, the positions reported by the system may depart from actual vehicle positions. Thus a travel route as reported by the system may fail to match the roads delineated in the database. Past attempts to match the travel route to a map make use of conventional pattern-matching to compare the vehicle's route with known roads close to the previous matched position. The road whose shape most closely approaches the previously matched road is selected as the one on which the vehicle must be traveling. Such a process takes considerable time if there are many roads and branches of roads in the area. U.S. Pat. No. 4,963,864 discloses another method, where pattern matching is performed for only a limited number of roads, thereby reducing the time required. A road is selected if the angle between the vector of current motion, as determined by GPS, Loran C, or dead reckoning, is within a predetermined value of the vector extending from the assumed current position. Pattern-matching between the road pattern selected and the vehicle's trajectory gives the position on the map, and the process is speeded up because only a limited number of roads is considered for matching. The computational load, although reduced, is still considerable, and the reduction in the number of roads considered may exclude the road on which the vehicle is actually located. Thus, the above methods fail to overcomes fully the drawbacks of incorrect positioning. OBJECTS AND SUMMARY OF THE INVENTION An object of the present invention is to provide a method for determining the path on a road map of a moving vehicle that overcomes the drawbacks of the prior art. A further object of the present invention is to determine efficiently the path on a road map of a moving vehicle by selecting only a limited number of roads for pattern matching. Still a further object of the present invention is to improve the efficiency of pattern matching of a vehicle travel path to a map by the use of fuzzy logic and approximate reasoning. Briefly stated, the present invention provides a vehicle navigation system that helps locate the vehicle on a road network by overcoming, through the use of fuzzy logic, the errors of positioning sensors and routing computers. In the system, sensors continually feed position coordinates to a processing unit that traces the vehicle's path in a road database. Fuzzy logic-based reasoning is used to determine the most probable location of the vehicle, whether off- or on-road, thereby correcting errors in its raw path as sensed or computed. According to an embodiment of the invention, there is provided a vehicle navigation system, which comprises: means for sensing a plurality of successive positions of the vehicle to create a sensed representation of a vehicle travel path, means for storing a map of roads in a vicinity of the vehicle, means for matching the sensed representation of a vehicle travel path with an actual vehicle travel path in the map, and the means for matching including fuzzy logic elements. According to a feature of the invention, there is provided a method for locating a position of a vehicle comprising: sensing a plurality of successive positions of the vehicle to produce a stored representation of a vehicle travel path, comparing the stored representation with a plurality of vehicle travel paths in a map, the step of comparing including employing fuzzy logic to best match the stored representation with one of the plurality of vehicle travel paths, whereby errors in the step of sensing can be overcome, and determining an actual position of the vehicle from the best match. According to a further feature of the invention there is provided a vehicle navigation system comprising: a plurality of positioning sensors to sense a plurality of successive positions of the vehicle, means for comparing the plurality of positions with a plurality of roads on a digitized map, fuzzy logic means for choosing a best fit between the plurality of positions and a one of the plurality of roads, and means, based on the best fit, for determining a vehicle present position on the one of the plurality of roads. The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a simplified view of a vehicle provided with a vehicle positioning system moving over a road network whose map is stored digitally in a database. FIG. 2 is a block diagram of the vehicle positioning system. FIG. 3 is a block diagram of a fuzzy logic system as employed by this invention. FIG. 4 is a flow chart of the program that matches the vehicle position to the map for the on-road case. FIG. 5 is a flow chart of the subprogram that retrieves successor roads. FIG. 6 is a flow chart of the subprogram that matches the vehicle position to the map for the off-road case. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a vehicle 10 moves over a road network 12 consisting of a plurality of roads 14-30 which have been digitized into a map. Vehicle 10 is provided with a vehicle positioning system 32 capable of carrying out the method of this invention. Also within road network 12 are a plurality of off-road locations that have not been digitized, for example, a parking facility 34. Referring to FIG. 2, vehicle positioning system 32 is comprised of a positioning sensor system 36, a signal processing unit 40, and a map-matching unit 44. A raw position, which may be either relative or absolute, from positioning sensor system 36 is fed over a line 38 to signal processing unit 40, which converts the information to X-Y coordinates of successive positions occupied over time by vehicle 10. Signal processing unit 40 feeds the X-Y coordinates to map-matching unit 44 over a line 42. The X-Y coordinates of the successive positions define a computed travel path over time. Though the computed travel path can in principal be matched to a road-following route in a road database 46 in practice errors from both positioning sensor system 36 and signal processing unit 40 make the shape of the computed travel path generally different from any route in road database 46. Therefore map-matching unit 44 must carry out a computer program to find the best fit of the computed travel path to the digitized map in road database 46. Man-matching unit 44 uses a computer program, as shown in FIGS. 4, 5, and 6, to match the computed travel path to the digitized map in road database 46, received over a line 48. The match yields a signal 50 representing a map-matched position. Signal 50 may be fed back to signal processing unit 40 over line 52 to correct positioning errors. Because of these errors, signal 50 is likely to be an inexact representation of the location of vehicle 10. Moreover, the prior art offers no means for choosing among a plurality of such inexact positions generated by signal processing unit 40. Therefore a means is required for correcting signal 50 to correspond with the precise location of vehicle 10. In this invention, fuzzy logic is employed to improve the accuracy of locating vehicle 10 precisely by establishing criteria of choice among a plurality of map-matched positions 50 drawn from the digitized maps in road database 46. The computer program carried out in map-matching unit 44 determines by fuzzy logic which of the plurality of signals 50 is the most likely to be the precise location of vehicle 10. The process of this invention, taking place in vehicle positioning unit 32, for determining the best location for vehicle 10, uses a system of fuzzy logic to assign truth values to each one of the plurality of signals 50 and to choose among them based on the assigned truth value. Referring to FIG. 3, one type of a fuzzy logic system 54 which may be used is composed of five principal units: a membership database 56 and a rule base 58, which are combined into a knowledge base 60; a fuzzifier 62; an inference engine 64; and a defuzzifier 66. Fuzzifier 62 converts an initial crisp value 68, which is deterministic, into an initial fuzzy set 70 by a known fuzzification method. Initial fuzzy set 70 is a qualitative representation, characterized by a membership function, of initial crisp value 68. Inference engine 64 operates on initial fuzzy set 70, in accordance with rules of fuzzy reasoning from rule base 58 and membership functions of fuzzy sets kept in membership database 56, to transform by inference initial fuzzy set 70 into a resulting fuzzy set 72 which is also qualitative. Then defuzzifier 66 converts the outcome of the fuzzy reasoning process, resulting fuzzy set 72, into a crisp outcome value 74 which is also deterministic. Referring to FIG. 4, an initial position of vehicle 10 is entered from signal processing unit 40. The initial position may be set by the operator, in which case it is assumed to be correct. If the operator sets the initial position, a candidate initial road is chosen uniquely from road database 46 if the vehicle is on-road. The initial position may also be set by the positioning sensor system 36, in which case it may or may not be correct. In that case, selection of the candidate initial road requires a choice according to criteria, for example, "ANY road within the error range of the sensor is a candidate, IF the road's configuration resembles the vehicle's travel path." The choice is made by fuzzy logic, for example, assigning a qualitative truth value comparing a vehicle heading with the candidate road's direction according to the rule, drawn from rule base 58, that "IF the difference between the heading value and the direction value are small, THEN the truth value is high." In this example, "small" and "high" are qualitative terms defined by membership functions drawn from membership database 56. If the truth value of the candidate road is greater than a predetermined value, then the candidate road is chosen. More than one rule or criterion may be applied at any step, for example, the distance between the vehicle position and the candidate road may be used. Where more than one rule is applied, the truth value is determined by combining the results from all rules that are applied. If no candidate road is chosen, i.e., no road in road database 46 meets the criteria of choice, the off-road flag is set to 1 (Step 101) and the program branches at C to the off-road subprogram shown in FIG. 6. The off-road flag may also be set to 1 and branching take place in response to an operator's input of an off-road initial position. Control returns to the main program at D after the off-road subprogram finishes executing. If the program in step 101 sets the off-road flag to 0, the vehicle is moving along the chosen road, and its further path must be delineated. In step 102 two consecutive positions of the vehicle are tested for a U-turn, again by fuzzy logic, for example, by applying the rule "IF the vehicle's heading has changed almost 180 degrees between successive positions, AND IF its motion is steady, AND IF its speed is reduced, THEN the probability of a U-turn is high," where "almost 180 degrees," "steady", and "high" are defined by membership functions. If in step 102 it is determined that the vehicle has made a U-turn, then the U-turn processor updates vehicle position information and sends it directly to step 111 for pattern matching. If the vehicle has not made a U-turn, in step 103 the program checks whether or not the vehicle has begun another type of turn. This check can be carried out by either binary or fuzzy logic. If turning has not begun, in step 104 the program checks whether the vehicle is passing over the same road as was chosen to match its previous position. If either step 103 or 104 returns a "yes", the program determines (step 106) whether or not to search for successor roads, which it does by fuzzy logic, for example, by applying the rule "IF the vehicle is in steady motion, AND IF the distance travelled along the chosen road is large compared to the chosen road's length, THEN the necessity to search for successor roads is high." If the conclusion is to search for successor roads, then the program branches at A to the subprogram shown in FIG. 5 that retrieves successor roads. (Control returns to the main program at B after the successor roads subprogram finishes executing.) If step 106 is performed and yields a "no", the program selects a most likely candidate road (step 107), based on the calculated path of travel. A "no" from step 104 or a selection from step 107 leads to a check by fuzzy logic whether the vehicle's motion is steady (step 105), using a rule such as, "IF the root mean square errors of the vehicle's heading and speed are small, THEN the motion is steady." If motion is not steady, the program goes directly to step 111. If motion is steady, the program evaluates by fuzzy logic the truth value of the correspondence between the vehicle travel path and the candidate road (step 108). The rule is of the form, "IF the truth value of the previous candidate road pattern is high, AND IF the truth value of the current candidate road pattern is high, THEN the truth value of the correspondence is high." Next, the truth value is tested against a predetermined value α (step 109). If the truth value is greater than α, the program moves to step 111. If the truth value is less, the candidate road is deleted (step 110). Finally, a pattern matching process that determines the current map-matched vehicle position in X-Y coordinates on the candidate road segment is performed (step 111) before the program terminates. Referring to FIG. 5, the subprogram to find successor roads starts from point A on FIG. 4. All roads that connect to the particular end of the current candidate road towards which vehicle 10 is moving are retrieved from road database 46 (step 201). Next a counter is set to choose the first road retrieved (step 202), and the value in the counter is compared to the number of successor roads retrieved (step 203). If the counter holds a number greater than the number of successor roads retrieved, the process of retrieving successor roads is terminated (step 204), the current candidate road is deleted (step 205), and the subprogram reenters the main program at point B on FIG. 4. If the counter holds a number less than or equal to the number of successor roads retrieved, the road whose number corresponds to the value of the counter is given a truth value (step 206) by fuzzy logic, using rules such as "IF the difference between the distance travelled along the current candidate road and the length of the candidate road is small, AND IF the difference between the vehicle heading and the orientation of the successor road is small, THEN the truth value of the successor road is high" and "IF the truth value of the candidate road is high AND IF the truth value of the successor road is high, THEN the combined truth value of the moving vehicle on the successor road is high." Next the truth value determined for the successor road is compared to a predetermined value β (step 207). If the value determined is less than β, the subprogram checks whether or not the vehicle is off-road, for example, in parking lot 34 (step 208), by fuzzy logic, using a rule such as "IF within a given distance no road pattern similar to the path of travel can be found, THEN the vehicle is off-road." If the result of step 208 is affirmative, the truth value is retained (step 209), the off-road flag is set to 1 (step 210), and the successor-road subprogram exits to the off-road subprogram in FIG. 6. If the result of step 208 is negative, the subprogram goes to step 212 where the counter is incremented by one and the subprogram returned to step 203. If the successor road's truth value is greater than β in step 207, the successor road becomes the new candidate road and a pattern match is performed (step 211) before the counter is incremented and the subprogram returned to step 203. Referring to FIG. 6, the off-road subprogram starts from point C on FIGS. 4 or 5. The program begins (step 301) by determining the vehicle's position, either by adding a relative displacement to the previous map-matched position or, if the position was determined absolutely, as, for example, from GPS, by displaying the output of signal processing unit 40. Then the subprogram checks (step 302) whether the vehicle may in fact be on-road. This check is made by fuzzy logic, using a rule, for example, "IF within a given distance there is more than one road pattern similar to the current vehicle motion, THEN the vehicle is on-road." The given distance may be defined as a function of: the truth value of the candidate road, the previous distance error between the calculated position from signal processing unit 40 and map-matched position 50, or the like. If the answer is affirmative, the off-road flag is set to 0 (step 303), and the subprogram terminates and returns control to the main program at D in FIG. 4. Since the map-matching process is performed continually as vehicle 10 moves along its route, the truth value of candidate roads constantly decreases. When only one candidate road remains, the truth value of this road should be reset to one. The result of the map-matching process shown in FIGS. 1-6 is a list of candidate roads, each of which has a different truth value. This truth value is a measure of the candidate road's resemblance to vehicle 10's travel path. The map matched position represented by signal 50 on the candidate road with the highest truth value is the likeliest position of vehicle 10 with reference to road database 46. Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.
A vehicle navigation system helps locate the vehicle on a road network by overcoming, through the use of fuzzy logic, the errors of positioning sensors and routing computers. In the system, sensors continually feed position coordinates to a processing unit that traces the vehicle's path in a road database. Fuzzy logic-based reasoning is used to determine the most probable location of the vehicle, whether off- or on-road, thereby correcting errors in its raw path as sensed or computed.
Summarize the document in concise, focusing on the main idea's functionality and advantages.
[ "BACKGROUND OF THE INVENTION This invention relates to a system for locating a vehicle and guiding it along its route, in which the vehicle's position in an area represented by a digitized map database is continuously determined.", "Since navigation and route guidance decisions are based on this continuously-determined position, it is necessary that the position be determined accurately.", "In known vehicle navigation systems, a vehicle's position is continuously determined in relative or absolute X-Y coordinates.", "This position determination is absolute, if determined, for example, by GPS (Global Positioning System) or Loran C, or relative, if determined by dead reckoning through the continuous integration of successive displacement vectors.", "However, the position so determined in either case is not always accurate.", "Because of errors in sensing and computation, the positions reported by the system may depart from actual vehicle positions.", "Thus a travel route as reported by the system may fail to match the roads delineated in the database.", "Past attempts to match the travel route to a map make use of conventional pattern-matching to compare the vehicle's route with known roads close to the previous matched position.", "The road whose shape most closely approaches the previously matched road is selected as the one on which the vehicle must be traveling.", "Such a process takes considerable time if there are many roads and branches of roads in the area.", "U.S. Pat. No. 4,963,864 discloses another method, where pattern matching is performed for only a limited number of roads, thereby reducing the time required.", "A road is selected if the angle between the vector of current motion, as determined by GPS, Loran C, or dead reckoning, is within a predetermined value of the vector extending from the assumed current position.", "Pattern-matching between the road pattern selected and the vehicle's trajectory gives the position on the map, and the process is speeded up because only a limited number of roads is considered for matching.", "The computational load, although reduced, is still considerable, and the reduction in the number of roads considered may exclude the road on which the vehicle is actually located.", "Thus, the above methods fail to overcomes fully the drawbacks of incorrect positioning.", "OBJECTS AND SUMMARY OF THE INVENTION An object of the present invention is to provide a method for determining the path on a road map of a moving vehicle that overcomes the drawbacks of the prior art.", "A further object of the present invention is to determine efficiently the path on a road map of a moving vehicle by selecting only a limited number of roads for pattern matching.", "Still a further object of the present invention is to improve the efficiency of pattern matching of a vehicle travel path to a map by the use of fuzzy logic and approximate reasoning.", "Briefly stated, the present invention provides a vehicle navigation system that helps locate the vehicle on a road network by overcoming, through the use of fuzzy logic, the errors of positioning sensors and routing computers.", "In the system, sensors continually feed position coordinates to a processing unit that traces the vehicle's path in a road database.", "Fuzzy logic-based reasoning is used to determine the most probable location of the vehicle, whether off- or on-road, thereby correcting errors in its raw path as sensed or computed.", "According to an embodiment of the invention, there is provided a vehicle navigation system, which comprises: means for sensing a plurality of successive positions of the vehicle to create a sensed representation of a vehicle travel path, means for storing a map of roads in a vicinity of the vehicle, means for matching the sensed representation of a vehicle travel path with an actual vehicle travel path in the map, and the means for matching including fuzzy logic elements.", "According to a feature of the invention, there is provided a method for locating a position of a vehicle comprising: sensing a plurality of successive positions of the vehicle to produce a stored representation of a vehicle travel path, comparing the stored representation with a plurality of vehicle travel paths in a map, the step of comparing including employing fuzzy logic to best match the stored representation with one of the plurality of vehicle travel paths, whereby errors in the step of sensing can be overcome, and determining an actual position of the vehicle from the best match.", "According to a further feature of the invention there is provided a vehicle navigation system comprising: a plurality of positioning sensors to sense a plurality of successive positions of the vehicle, means for comparing the plurality of positions with a plurality of roads on a digitized map, fuzzy logic means for choosing a best fit between the plurality of positions and a one of the plurality of roads, and means, based on the best fit, for determining a vehicle present position on the one of the plurality of roads.", "The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a simplified view of a vehicle provided with a vehicle positioning system moving over a road network whose map is stored digitally in a database.", "FIG. 2 is a block diagram of the vehicle positioning system.", "FIG. 3 is a block diagram of a fuzzy logic system as employed by this invention.", "FIG. 4 is a flow chart of the program that matches the vehicle position to the map for the on-road case.", "FIG. 5 is a flow chart of the subprogram that retrieves successor roads.", "FIG. 6 is a flow chart of the subprogram that matches the vehicle position to the map for the off-road case.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a vehicle 10 moves over a road network 12 consisting of a plurality of roads 14-30 which have been digitized into a map.", "Vehicle 10 is provided with a vehicle positioning system 32 capable of carrying out the method of this invention.", "Also within road network 12 are a plurality of off-road locations that have not been digitized, for example, a parking facility 34.", "Referring to FIG. 2, vehicle positioning system 32 is comprised of a positioning sensor system 36, a signal processing unit 40, and a map-matching unit 44.", "A raw position, which may be either relative or absolute, from positioning sensor system 36 is fed over a line 38 to signal processing unit 40, which converts the information to X-Y coordinates of successive positions occupied over time by vehicle 10.", "Signal processing unit 40 feeds the X-Y coordinates to map-matching unit 44 over a line 42.", "The X-Y coordinates of the successive positions define a computed travel path over time.", "Though the computed travel path can in principal be matched to a road-following route in a road database 46 in practice errors from both positioning sensor system 36 and signal processing unit 40 make the shape of the computed travel path generally different from any route in road database 46.", "Therefore map-matching unit 44 must carry out a computer program to find the best fit of the computed travel path to the digitized map in road database 46.", "Man-matching unit 44 uses a computer program, as shown in FIGS. 4, 5, and 6, to match the computed travel path to the digitized map in road database 46, received over a line 48.", "The match yields a signal 50 representing a map-matched position.", "Signal 50 may be fed back to signal processing unit 40 over line 52 to correct positioning errors.", "Because of these errors, signal 50 is likely to be an inexact representation of the location of vehicle 10.", "Moreover, the prior art offers no means for choosing among a plurality of such inexact positions generated by signal processing unit 40.", "Therefore a means is required for correcting signal 50 to correspond with the precise location of vehicle 10.", "In this invention, fuzzy logic is employed to improve the accuracy of locating vehicle 10 precisely by establishing criteria of choice among a plurality of map-matched positions 50 drawn from the digitized maps in road database 46.", "The computer program carried out in map-matching unit 44 determines by fuzzy logic which of the plurality of signals 50 is the most likely to be the precise location of vehicle 10.", "The process of this invention, taking place in vehicle positioning unit 32, for determining the best location for vehicle 10, uses a system of fuzzy logic to assign truth values to each one of the plurality of signals 50 and to choose among them based on the assigned truth value.", "Referring to FIG. 3, one type of a fuzzy logic system 54 which may be used is composed of five principal units: a membership database 56 and a rule base 58, which are combined into a knowledge base 60;", "a fuzzifier 62;", "an inference engine 64;", "and a defuzzifier 66.", "Fuzzifier 62 converts an initial crisp value 68, which is deterministic, into an initial fuzzy set 70 by a known fuzzification method.", "Initial fuzzy set 70 is a qualitative representation, characterized by a membership function, of initial crisp value 68.", "Inference engine 64 operates on initial fuzzy set 70, in accordance with rules of fuzzy reasoning from rule base 58 and membership functions of fuzzy sets kept in membership database 56, to transform by inference initial fuzzy set 70 into a resulting fuzzy set 72 which is also qualitative.", "Then defuzzifier 66 converts the outcome of the fuzzy reasoning process, resulting fuzzy set 72, into a crisp outcome value 74 which is also deterministic.", "Referring to FIG. 4, an initial position of vehicle 10 is entered from signal processing unit 40.", "The initial position may be set by the operator, in which case it is assumed to be correct.", "If the operator sets the initial position, a candidate initial road is chosen uniquely from road database 46 if the vehicle is on-road.", "The initial position may also be set by the positioning sensor system 36, in which case it may or may not be correct.", "In that case, selection of the candidate initial road requires a choice according to criteria, for example, "ANY road within the error range of the sensor is a candidate, IF the road's configuration resembles the vehicle's travel path.", """, "The choice is made by fuzzy logic, for example, assigning a qualitative truth value comparing a vehicle heading with the candidate road's direction according to the rule, drawn from rule base 58, that "IF the difference between the heading value and the direction value are small, THEN the truth value is high.", """, "In this example, "small"", "and "high"", "are qualitative terms defined by membership functions drawn from membership database 56.", "If the truth value of the candidate road is greater than a predetermined value, then the candidate road is chosen.", "More than one rule or criterion may be applied at any step, for example, the distance between the vehicle position and the candidate road may be used.", "Where more than one rule is applied, the truth value is determined by combining the results from all rules that are applied.", "If no candidate road is chosen, i.e., no road in road database 46 meets the criteria of choice, the off-road flag is set to 1 (Step 101) and the program branches at C to the off-road subprogram shown in FIG. 6. The off-road flag may also be set to 1 and branching take place in response to an operator's input of an off-road initial position.", "Control returns to the main program at D after the off-road subprogram finishes executing.", "If the program in step 101 sets the off-road flag to 0, the vehicle is moving along the chosen road, and its further path must be delineated.", "In step 102 two consecutive positions of the vehicle are tested for a U-turn, again by fuzzy logic, for example, by applying the rule "IF the vehicle's heading has changed almost 180 degrees between successive positions, AND IF its motion is steady, AND IF its speed is reduced, THEN the probability of a U-turn is high,"", "where "almost 180 degrees,"", ""steady", and "high"", "are defined by membership functions.", "If in step 102 it is determined that the vehicle has made a U-turn, then the U-turn processor updates vehicle position information and sends it directly to step 111 for pattern matching.", "If the vehicle has not made a U-turn, in step 103 the program checks whether or not the vehicle has begun another type of turn.", "This check can be carried out by either binary or fuzzy logic.", "If turning has not begun, in step 104 the program checks whether the vehicle is passing over the same road as was chosen to match its previous position.", "If either step 103 or 104 returns a "yes", the program determines (step 106) whether or not to search for successor roads, which it does by fuzzy logic, for example, by applying the rule "IF the vehicle is in steady motion, AND IF the distance travelled along the chosen road is large compared to the chosen road's length, THEN the necessity to search for successor roads is high.", """, "If the conclusion is to search for successor roads, then the program branches at A to the subprogram shown in FIG. 5 that retrieves successor roads.", "(Control returns to the main program at B after the successor roads subprogram finishes executing.) If step 106 is performed and yields a "no", the program selects a most likely candidate road (step 107), based on the calculated path of travel.", "A "no"", "from step 104 or a selection from step 107 leads to a check by fuzzy logic whether the vehicle's motion is steady (step 105), using a rule such as, "IF the root mean square errors of the vehicle's heading and speed are small, THEN the motion is steady.", """, "If motion is not steady, the program goes directly to step 111.", "If motion is steady, the program evaluates by fuzzy logic the truth value of the correspondence between the vehicle travel path and the candidate road (step 108).", "The rule is of the form, "IF the truth value of the previous candidate road pattern is high, AND IF the truth value of the current candidate road pattern is high, THEN the truth value of the correspondence is high.", """, "Next, the truth value is tested against a predetermined value α (step 109).", "If the truth value is greater than α, the program moves to step 111.", "If the truth value is less, the candidate road is deleted (step 110).", "Finally, a pattern matching process that determines the current map-matched vehicle position in X-Y coordinates on the candidate road segment is performed (step 111) before the program terminates.", "Referring to FIG. 5, the subprogram to find successor roads starts from point A on FIG. 4. All roads that connect to the particular end of the current candidate road towards which vehicle 10 is moving are retrieved from road database 46 (step 201).", "Next a counter is set to choose the first road retrieved (step 202), and the value in the counter is compared to the number of successor roads retrieved (step 203).", "If the counter holds a number greater than the number of successor roads retrieved, the process of retrieving successor roads is terminated (step 204), the current candidate road is deleted (step 205), and the subprogram reenters the main program at point B on FIG. 4. If the counter holds a number less than or equal to the number of successor roads retrieved, the road whose number corresponds to the value of the counter is given a truth value (step 206) by fuzzy logic, using rules such as "IF the difference between the distance travelled along the current candidate road and the length of the candidate road is small, AND IF the difference between the vehicle heading and the orientation of the successor road is small, THEN the truth value of the successor road is high"", "and "IF the truth value of the candidate road is high AND IF the truth value of the successor road is high, THEN the combined truth value of the moving vehicle on the successor road is high.", """, "Next the truth value determined for the successor road is compared to a predetermined value β (step 207).", "If the value determined is less than β, the subprogram checks whether or not the vehicle is off-road, for example, in parking lot 34 (step 208), by fuzzy logic, using a rule such as "IF within a given distance no road pattern similar to the path of travel can be found, THEN the vehicle is off-road.", """, "If the result of step 208 is affirmative, the truth value is retained (step 209), the off-road flag is set to 1 (step 210), and the successor-road subprogram exits to the off-road subprogram in FIG. 6. If the result of step 208 is negative, the subprogram goes to step 212 where the counter is incremented by one and the subprogram returned to step 203.", "If the successor road's truth value is greater than β in step 207, the successor road becomes the new candidate road and a pattern match is performed (step 211) before the counter is incremented and the subprogram returned to step 203.", "Referring to FIG. 6, the off-road subprogram starts from point C on FIGS. 4 or 5.", "The program begins (step 301) by determining the vehicle's position, either by adding a relative displacement to the previous map-matched position or, if the position was determined absolutely, as, for example, from GPS, by displaying the output of signal processing unit 40.", "Then the subprogram checks (step 302) whether the vehicle may in fact be on-road.", "This check is made by fuzzy logic, using a rule, for example, "IF within a given distance there is more than one road pattern similar to the current vehicle motion, THEN the vehicle is on-road.", """, "The given distance may be defined as a function of: the truth value of the candidate road, the previous distance error between the calculated position from signal processing unit 40 and map-matched position 50, or the like.", "If the answer is affirmative, the off-road flag is set to 0 (step 303), and the subprogram terminates and returns control to the main program at D in FIG. 4. Since the map-matching process is performed continually as vehicle 10 moves along its route, the truth value of candidate roads constantly decreases.", "When only one candidate road remains, the truth value of this road should be reset to one.", "The result of the map-matching process shown in FIGS. 1-6 is a list of candidate roads, each of which has a different truth value.", "This truth value is a measure of the candidate road's resemblance to vehicle 10's travel path.", "The map matched position represented by signal 50 on the candidate road with the highest truth value is the likeliest position of vehicle 10 with reference to road database 46.", "Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims." ]
FIELD OF THE INVENTION The present invention relates to stents having cavities capable of incorporating biologically active agents therein. More particularly, the present invention relates to stents that are highly flexible, easily used in a wide variety of situations, and that can continuously deliver diagnostic and/or therapeutic agents for an extended period directly at the site of stent placement. In another aspect, the present invention relates to methods of making stents having such properties. Stents according to the present invention are especially useful for vascular treatment. BACKGROUND OF THE INVENTION Cardiovascular disease, including atherosclerosis, is the leading cause of death in the United States. The medical community has developed a number of methods for treatment of coronary heart disease, some of which are specifically designed to treat complications resulting from atherosclerosis and other forms of coronary arterial narrowing. In another form, arterial wall degeneration with the formation of aneurysms causes arterial wall thinning. Management of the dilated arteries in the peripheral circulation has come under the domain of vascular surgeons. Investigators in the field of vascular surgery had at one time handled both narrowed and dilated arteries by techniques for suture anastomosis (sewing together) of two arterial segments using needle and thread. Today, there is a significantly less invasive clinical approach known as endovascular grafting. However, the most compelling development in the past decade is percutaneous transluminal coronary angioplasty (PTCA, or simply “angioplasty”). The objective in angioplasty is to enlarge the lumen of the affected coronary artery by radial hydraulic expansion. The procedure is accomplished by inflating a balloon within the narrowed lumen of the coronary artery. Radial expansion of the coronary artery occurs in several different dimensions and is related to the nature of the plaque. Soft, fatty plaque deposits are flattened by the balloon and hardened deposits are cracked and split to enlarge the lumen. The wall of the artery itself is stretched when the balloon is inflated. PTCA is performed as follows: A thin walled, hollow guiding catheter is typically introduced into the body via a relatively large vessel, such as the femoral artery in the groin area or the brachial artery in the arm. Access to the femoral artery is achieved by introducing a large bore needle directly into the femoral artery, a procedure known as the Seldinger technique. Once access to the femoral artery is achieved, a short hollow sheath is introduced to maintain a passageway during PTCA. The flexible guiding catheter, which is typically polymer coated, and lined with Teflon™, is inserted through the sheath into the femoral artery. The guiding catheter is advanced through the femoral artery into the iliac artery and into the ascending aorta. Further advancement of the flexible catheter involves the negotiation of an approximately 180 degree turn through the aortic arch to allow the guiding catheter to descend into the aortic cusp where entry may be gained to either the left or the right coronary artery as desired. After the guiding catheter is advanced to the ostium of the coronary artery to be treated by PTCA, a flexible guidewire is inserted into the guiding catheter through a balloon and advanced to the area to be treated. The guide wire provides the necessary steerability for lesion passage. The guidewire is advanced across the lesion, or “wires” the lesion, in preparation for the advancement of the balloon catheter across the guide wire. The balloon, or dilatation, catheter is placed in position by sliding it along the guide wire. The use of a relatively rigid guide wire is necessary to advance the catheter through the narrowed lumen of the artery and to direct the balloon, which is typically quite flexible, across the lesion. Radiopaque markers in the balloon segments of the catheter facilitate positioning across the lesion. The balloon catheter is then inflated with contrast material to permit fluoroscopic viewing during treatment. The balloon is alternately inflated and deflated until the lumen of the artery is satisfactory enlarged. By way of example, further details of angioplasty procedures and devices used in such procedures can be found in U.S. Pat. No. 4,327,071 (Simpson et al.), U.S. Pat. No. 4,332,254 (Lundquist), U.S. Pat. No. 4,439,185 (Lundquist), U.S. Pat. No. 4,468,224 (Enzmann et al.), U.S. Pat. No. 4,516,972 (Samson), U.S. Pat. No. 4,582,181 (Samson), U.S. Pat. No. 4,748,982 (Horzewski et al.), U.S. Pat. No. 4,771,778 (Mar), and U.S. Pat. No. 4,793,350 (Mar et al.), each of which is hereby incorporated by reference herein. A common problem that sometimes occurs after an angioplasty procedure is the appearance of restenosis at or near the site of the original stenosis in the blood vessel, which requires a secondary angioplasty procedure or bypass surgery. Another occurrence which reduces the success of angioplasty procedures is the collapse of a section of the dissected lining (commonly termed a “flap”) into the blood stream upon deflation of the balloon, thereby closing or significantly reducing the blood flow through the vessel. In this instance, emergency bypass surgery is sometimes required to avoid a myocardial infarct distal blockage. On some occasions, the dilatation catheter can be replaced with a perfusion type dilatation catheter such as described in U.S. Pat. No. 4,790,315 (Mueller, Jr. et al.) in order to hold the blood vessel open for extended periods. However, perfusion type dilatation catheters have relatively large profiles which can make advancement thereof through the blockage difficult, and therefore immediate bypass surgery may be the only means of avoiding an infarct distal to the blockage or possibly even death. Additionally, the inflated balloon of these perfusion catheters can block off a branch artery, thus creating ischemic conditions in the side branch distal to the blockage. In recent years, various devices and methods for prevention of restenosis and repairing damaged blood vessels have been developed which typically use an expandable cage or region commonly termed a “stent” which is placed on the distal end of a catheter, and is designed to hold a detached lining against an arterial wall for extended periods to facilitate the reattachment thereof. Stents are generally cylindrically shaped intravascular devices which in some cases can also be used as the primary treatment devices where they are expanded to dilate a stenosis and then left in place. Various types of stents and stent delivery systems are disclosed in U.S. Pat. No. 3,868,956 (Alfidi et al.), U.S. Pat. No. 4,503,569 (Dotter), U.S. Pat. No. 4,512,338 (Balko et al.), U.S. Pat. No. 4,553,545 (Maass et al.), U.S. Pat. No. 4,655,771 (Wallsten), U.S. Pat. No. 4,665,918 (Garza et al.), U.S. Pat. No. 4,733,665 (Palmaz), U.S. Pat. No. 4,795,458 (Regan), U.S. Pat. No. 4,800,882 (Gianturco), U.S. Pat. No. 4,830,003 (Wolff et al.), U.S. Pat. No. 4,856,516 (Hillstead), U.S. Pat. No. 4,878,906 (Lindemann et al.), U.S. Pat. No. 4,886,062 (Wiktor), U.S. Pat. No. 4,907,336 (Gianturco), U.S. Pat. No. 5,201,757 (Heyn et al.), U.S. Pat. No. 5,234,457 (Andersen), U.S. Pat. No. 5,292,331 (Boneau), U.S. Pat. No. 5,314,444 (Gianturco), U.S. Pat. No. 5,344,426 (Lau et al.), U.S. Pat. No. 5,372,600 (Beyar et al.), U.S. Pat. No. 5,387,235 (Chuter), U.S. Pat. No. 5,449,373 (Pinchasik et al.), U.S. Pat. No. 5,540,712 (Kleshinski et al.), U.S. Pat. No. 5,549,662 (Fordenbacher), U.S. Pat. No. 5,591,197 (Orth et al.), U.S. Pat. No. 5,593,434 (Williams), U.S. Pat. No. 5,599,576 (Opolski), U.S. Pat. No. 5,607,467 (Froix), U.S. Pat. No. 5,603,721 (Lau et al.), U.S. Pat. No. 5,605,530 (Fischell et al.), U.S. Pat. No. 5,382,261 (Palmaz), U.S. Pat. No. 5,549,635 (Solar), U.S. Pat. No. 5,500,013 (Buscemi et al.), U.S. Pat. No. 5,234,456 (Silvestrini), U.S. Pat. No. 5,342,348 (Kaplan), U.S. Pat. No. 5,368,566 (Crocker), U.S. Pat. No. 5,383,928 (Scott et al.), U.S. Pat. No. 5,423,885 (Williams), U.S. Pat. No. 5,443,458 (Eury), U.S. Pat. No. 5,464,450 (Buscemi et al.), U.S. Pat. No. 5,464,650 (Berg et al.), U.S. Pat. No. 5,618,299 (Khosravi et al.), U.S. Pat. No. 5,637,113 (Tartaglia et al.), U.S. Pat. No. 5,649,977 (Campbell), U.S. Pat. No. 5,419,760 (Narciso, Jr.), U.S. Pat. No. 5,651,174 (Schwartz et al.), and U.S. Pat. No. 5,556,413 (Lam), each of which is hereby incorporated by reference herein. See especially U.S. Pat. No. 4,800,882 to Gianturco, U.S. Pat. No. 5,234,457 to Andersen, U.S. Pat. No. 4,856,516 to Hillstead, and U.S. Pat. No. 5,500,013 to Buscemi et al. Because it is of utmost importance to avoid thrombosis of the stent and its serious complications, patients who receive stents are often aggressively treated with anticoagulants such as heparin, aspirin, coumadin, dextran, and/or persantine. As expected, there is a high incidence of bleeding complications in these patients. A study performed at Emory University Hospital revealed that 33% of the patients who received stents for acute closure required transfusion, and 7% of the patients had an extremely large bleeding episode at the catheter entry site in the leg artery that necessitated surgical repair (Hearn et al., J. Am. Coll. Cardiol., (1992). Because of the complications associated with systemic treatment with anticoagulants, extensive attempts have been made to desing a stent that would be non-thrombogenic. A stent with little or no propensity to form thrombus would drastically decrease the need for aggressive treatment with anticoagulants. Initially, stents were constructed of plastic. Because all of these stents caused thrombosis, stainless steel was then tried. These stents appeared promising in studies in canine peripheral arteries. However, most coronary stents used to date in clinical trials are composed of stainless steel and yet still have a thrombotic occlusion rate of approximately 5-30%. Tantalum is another metal that is used in stents. Although initial reports of a lower thrombogenicity of tantalum stents appeared promising (van der Giessen et al., Circulation, 80:II-173 (1989)), more careful study has shown that tantalum is as thrombogenic as stainless steel (de Jaegere et al., Amer. J. Cardiol., 69:598-602 (1992)). The concept of coating a stent with a polymer was described several years ago and is discussed in the literature regularly. In the past, local delivery of drug(s) using stents has centered around two concepts: (1) directly coating the stent wires with a drug or a drug-polymer combination (Bailey et al., Circulation, 82:III-541 (1990); and Cavendar et al., Circulation, 82:III-541 (1990)); and (2) incorporating a drug into a stent that is constructed of a biodegradable polymer (Murphy et al., J. Invasive Cardiol., 3:144-48 (1991)). Most investigators and stent companies have focussed their efforts on directly coating the metal stent wires with a polymer. This polymer is usually placed directly on the stent (e.g., by dipping the stent in soluble polymer) or is covalently bound to the metal. The polymer is bonded to or contains an anticoagulant compound most coated stents currently under development use heparin as their active agent. One of the more effective polymer coatings for stents is Biogold (van der Giessen, Circulation, 82:III-542 (1990)). Significant difficulties have been encountered with all prior art stents. Each has its percentage of thrombosis, restenosis, and tissue in-growth problems, as well as various degrees of difficulty of deployment. Another difficulty is that many prior art stents do not conform well to the vessel lumen. Some prior art stents require administration of anticoagulant medication to the patient for up to three months following their placement inside the body. What has been needed and heretofore unavailable in the art is a stent that can be quickly and easily used in a wide variety of situations, that keeps the vessel open with a minimum degree of recoil and shortening lengthwise, that is flexible and can be delivered to the most distal lesion, and that can continuously deliver anticoagulant or other biologically active agents for an extended period directly at the site of stent placement. SUMMARY OF THE INVENTION The present invention fills the above-described needs in the art by providing a stent that can be quickly and easily used in a wide variety of situations, that keeps the vessel open with a minimum degree of recoil and shortening lengthwise, that is flexible and can be delivered to the most distal lesion, and that can continuously deliver biologically active agents for an extended period directly at the site of stent placement. The present invention substantially reduces the complications and overcomes the limitations of prior art devices. In accordance with the present invention, there are provided flexible stents that can be delivered through a curved body conduit using a routine medical procedure and a conventional stent delivery system. Stents produced according to the present invention do not cause significant thrombosis at the point of implant, nor do they cause significant restenosis after implantation. Thus, the present invention provides stents that have superior performance characteristics, as well as certain production advantages, as compared to prior art devices. Therefore, the articles and methods of the present invention are extremely useful in coronary artery balloon angioplasty, as well as related medical procedures where it is useful to provide a stent to any body lumen. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a sheet of material to be used to form a stent according to the present invention, wherein the pattern of material to be removed is shown. FIG. 2 is a plan view of a partially-formed stent according to one embodiment the present invention, wherein the appropriate portions of the sheet of material have been removed. FIG. 3 is a plan view of a partially-formed stent according to one embodiment the present invention, wherein the partially-formed stent of FIG. 2 has been bent to create the serpentine backbone, and the cavities have been added. FIG. 4 is a plan view of an alternative embodiment of the partially-formed stent of FIG. 3, further including a secondary backbone in addition to the serpentine backbone. FIG. 5 is an elevation view of a stent according to the present invention, prior to placement and expansion within a body lumen. FIG. 6 is an elevation view of the stent of FIG. 5 as it would appear after placement and expansion. DETAILED DESCRIPTION OF THE INVENTION The above features and advantages of the present invention, as well as others are accomplished by providing a stent comprising a flexible, serpentine backbone and a plurality of cavities capable of incorporating biologically active agents therein. Also provided according to the present invention is a stent comprising at least one flexible, serpentine backbone and a plurality of opposing, outwardly-projecting appendages on said backbone; wherein said stent has a substantially circular cross-section. Also provided according to the present invention is a method of producing a stent, said method comprising machining a sheet of material to create a leaving portion and a stent-forming portion, said stent-forming portion comprising at least one flexible, serpentine backbone and a plurality of opposing, outwardly-projecting appendages on said backbone, and shaping said stent-forming portion to have a substantially circular cross-section, thereby forming said stent. Also provided according to the present invention is another method of producing a stent, said method comprising wrapping a length of wire around appropriately placed guideposts to create a pre-stent comprising at least one flexible, serpentine backbone and a plurality of opposing, outwardly-projecting appendages on said backbone, fastening the base of each of said appendages to said backbone, and shaping said pre-stent to have a substantially circular cross-section, thereby forming said stent. Also provided according to the present invention is still another method of producing a stent, said method comprising machining a tube of material to create a leaving portion and a stent-forming portion, said stent-forming portion comprising at least one flexible, serpentine backbone and a plurality of opposing, outwardly-projecting appendages on said backbone. While the primary application for stents according to the invention is presently treatment of cardiovascular disease such as atherosclerosis or other forms of coronary narrowing, stents according to the present invention may also be used for treatment of narrowing vessels in kidney lumens, respiratory lumens, urogenital lumens, bileducts, or elsewhere in the body. In such other vessels, the size of the stent may be adjusted to compensate for differing sizes of the vessel to be treated. Referring first to FIG. 5, one embodiment of a stent according to the invention is shown. A stent 1 comprises a semi-rigid, serpentine backbone 2 on which is attached several appendages 3 . The dimensions and shape of the stent 1 can vary dramatically. Of course, a major factor in selecting stent size is the intended biological use thereof. Obviously, the dimensions of the body lumen into which the stent 1 will be placed is a primary factor in determining the preferred shape and size. However, generally speaking, it is preferred that the stent 1 have a circular cross-section throughout its length. Additionally, it is usually simplest and best if the stent 1 is generally. cylindrical in shape. In another preferred alternative embodiment, the stent 1 is frustoconical (i.e., lampshade-shaped), as this enables the stent 1 to be introduced into a body lumen narrow-end-first, thus allowing for easier transluminal movement of the stent 1 . Of course, those of skill in the art can develop many alternative shapes that can be used as well. It is generally preferred that the stent 1 has a length of about 6 mm to about 200 mm. In a more preferred embodiment, the stent 1 has a length of about 10 mm to about 25 mm. In a most preferred embodiment (especially with respect to vascular placement), the stent 1 has a length of about 12 mm to about 18 mm. Although the stent 1 may be formed by first creating the backbone 2 and then attaching the appendages 3 thereto, it is presently preferred that the stent 1 be integrally formed from a single piece of material. By integrally formed, it is meant that the stent 1 is made from a single and continuous piece, sheet, tube, or other starting form of material, with no welds, adhesives, or other non-integral forms of attachment being used. Stents according to the present invention may be formed of a variety of materials that have the appropriate characteristics of formability, strength, flexibility, melting point, and non-reactivity with biological components. Thus, preferred materials for construction of a stent according to the invention are MP-35N, nitinol, ELGILOY™, platinum, platinum-tungsten, platinum-nickel, platinum-rhenium, stainless steel, gold, tantalum, titanium aluminide, polyurethane, silicone elastomers, polytetrafluoroethylene, combinations thereof, and the like. Presently, MP-35N is the most preferred material for construction of a stent according to the invention. Although the backbone 2 is shown in FIG. 5 as having a shape similar to a regular, repeating sine-wave, it may be of many different shapes and still be within the scope of the present invention. The advantage of the serpentine backbone 2 , as contrasted with comparable elements in prior art devices, is its non-linear and therefore more flexible shape. By being non-linear, the backbone 2 has a plurality of built-in flex points. These flex points, and the resulting increase in flexibility, enhance the ability of the doctor to transluminally move a stent according to the invention through tortuous anatomy to the desired site of use. Thus, in addition to the regular sine-wave shape seen in FIG. 5, backbone 2 may also have successive curves or waves in a non-regular pattern (i.e., successive waves having variances in frequency and/or amplitude, in repeating or non-repeating patterns), successive corners of varying angles in repeating or non-repeating patterns, combinations of curves and corners, or the like. Because the backbone 2 is non-linear, its length, as measured along the curve, is greater than the length of the stent 1 itself. In a preferred embodiment, the length of the backbone 2 , as measured along the curve thereof, is about 1.5 to about 4 times longer than the stent 1 . In a most preferred embodiment, the length of the backbone 2 , as measured along the curve thereof, is about 2 to about 3 times longer than the stent 1 . While the backbone 2 is required to support the appendages 3 , it is the appendages 3 that actually do the work of supporting the vessel into which the stent 1 is placed. The appendages 3 may be in a wide variety of shapes and sizes sufficient to support the vessel. It is generally preferred that the appendages 3 have a relatively large hole 4 therein, as can be clearly seen in FIG. 5 . By having a large hole 4 in each appendage 3 , the appendages 3 as a group can effectively support a larger surface area of the lumen, while not completely covering the tissue at that surface. Additionally, in preferred embodiments the appendages 3 are loop-shaped, rectangular, square-wave-shaped, teardrop-shaped, trapezoidal, rhomboidal, combinations thereof, or the like. In a presently preferred embodiment, the appendages 3 are loop-shaped. As mentioned above, while a variety of sizes are possible, and the preferred size of the appendages 3 depends mostly upon the size of the lumen in which the stent 1 will be used, it is generally preferred that the appendages 3 have a length of about 5 mm to about 200 mm, and a width of about 0.5 mm to about 5 mm. In a presently preferred embodiment, the appendages 3 have a length of about 0.5 mm to about 5 mm and a width of about 0.5 mm to about 4 mm. While not required, it is preferred that the appendages 3 be present down the entire length of the stent 1 . It is generally preferred that each stent 1 includes about 5 to about 40 appendages thereon. In a presently preferred embodiment, each stent 1 includes about 10 to about 20 appendages thereon. Thus, it is generally preferred that the distance between each of the appendages 3 on a single stent 1 is about 0.1 mm to about 1.5 mm. Because the appendages 3 do not interconnect to one another, they can be seen to permit the stent 1 to be compressed or expanded over a wide range of diameters while still maintaining the significant mechanical force required to prevent a vessel from recoiling or collapsing. While it is generally preferred that there be some degree of overlap between the appendages 3 extending from each side of the stent 1 (see FIG. 5) when the stent 1 is either expanded or contracted, this is not an absolute requirement. The degree of radial compliance of a stent will be dependent upon the strength of the metal alloy, the thickness of the stent strud, the proximity of successive appendages (i.e., the inter-appendage interval), and the angle of orientation of the appendages. In the presently preferred embodiment, the stent according to the present invention includes a plurality of cavities 5 thereon, as seen in FIG. 4 . The cavities are essentially relatively small holes or craters in the stent that may be filled with a biologically active agent or biologically active agent-containing formulation. By pre-filling the cavities with a biologically active agent prior to placement of the stent, the biologically active agent will be released into the patient after placement. Because the biologically active agent will be released at the site of placement, the biologically active agent can have its greatest effects directly at the desired location, without prior dilution throughout the body of the patient. Preferably, each stent 1 will include about 8 to about 400 cavities 5 . While the cavities 5 may be of almost any three-dimensional size or shape, in a preferred embodiment the cavities 5 are essentially hemispherical, slit-like, cubical, rectangular, teardrop-shaped, or the like. In a presently preferred embodiment, the cavities 5 are essentially circular in shape. The size of the cavities 5 is relatively unimportant, as long as the cavities 5 are large enough to hold the desired amount of biologically active agent. However, it is presently preferred that each of the cavities 5 has a volume of about 0.02 mm 3 to about 4 mm 3 . The cavities 5 may contain any desired biologically active agent. The term “biologically active agent” is used herein in an extremely expansive sense, and generally indicates any biologically active or diagnostically useful substance, including drugs, radioactive chemicals, gene therapy vectors, and the like. Exemplary drugs for use in the present invention are heparin, tissue plasminogen activator, coumadin, protamine, urokinase, hirudin, argatroban, forskolin, vapiprost, prostacyclin, prostacyclin analogues, dextran, D-phe-pro-arg-chloromethylketone, dipyridamole, glycoprotein IIb/IIIa platelet membrane receptor antibody, angiopeptin, angiotensin converting enzyme inhibitors, (such as Captopril™, Cilazapril™, Lisinopril™), calcium channel blockers, colchicine, fibroblast growth factor antagonists, fish oil, omega 3-fatty acids, histamine antagonists, HMG-CoA reductase inhibitor, methotrexate, azathioprine, vincristine, vinblastine, fluorouracil, adriamycin, mutamycin, monoclonal antibodies, nitroprusside, phosphodiesterase inhibitors, prostaglandin inhibitor, seramin, serotonin blockers, steroids, thioprotease inhibitors, triazolopyrimidine and other PDGF antagonists, alpha-interferon, glucocorticoids, dexamethasone, betamethasone, tocopherol, aspirin, ticlopdine, ACA inhibitors, growth factors, oligonucleotides, antimitotic agents, antioxidants, antimetabolite agents, phosphorylcholine, antibiotics, anti-inflammatories, narcotics, anti-platelet drugs, cytostatic agents, antiproliferative agents, and the like. Exemplary radioactive chemicals include iridium, cesium, cobalt, and any other elements or compounds that contain radioactive isotopes. Presently, the most preferred biologically active agents are those that serve as anti-thrombus agents and/or anti-restenosis agents, as these are the most desirable biologically active agents for localization to the site of placement (when the stent 1 is used intravascularly). The biologically active agent, or any formulation, containing the same, may be introduced into the cavities 5 by any suitable means known to those skilled in the art. For example, the stent 1 may be dipped into or otherwise coated with a liquid that includes the biologically active agent such that the liquid is drawn into the cavities 5 by surface tension affects. The liquid may subsequently be dried, or not, as desired. Alternatively, a biologically active agent in powder form may be “rubbed” into the cavities 5 . As another alternative, the biologically active agent may be combined with a polymeric material having controlled-release properties, and each of the cavities 5 carefully filled with this mixture. Many other alternatives will occur to those of skill in the art. Furthermore, the biologically active agent may be added to the cavities 5 either as part of the manufacturing process, or immediately prior to placement of the stent 1 in a body lumen. In one embodiment, the cavities 5 do not extend through the entire thickness of the stent 1 . In this case, the cavities 5 might be best described as craters, as opposed to holes. In such embodiments, the cavities 5 may be present on only an inner surface of the stent 1 , on only an outer surface of the stent 1 , or both surfaces simultaneously. When the stent 1 has cavities 5 on both its inner surface and outer surface, the stent 1 may contain a first biologically active agent in those cavities 5 on the inner surface, and a second biologically active agent in those cavities 5 on the outer surface. In such an embodiment, it is preferred that the first biologically active agent is an anti-thrombus agent, and the second biologically active agent is an anti-restenosis drug. Instead of, or in addition to, the use of cavities 5 , the stent according to the present invention may include a biologically active agent-impregnated polymeric material coating all or a portion of the appendages 3 . As is known to those of skill in the art, a wide variety of polymeric materials can either be formed with a releasable biologically active agent therein, or a biologically active agent may be absorbed by the polymeric material after its formation. By coating the appendages 3 with such a biologically active agent-impregnated polymeric material prior to placement inside a biological lumen, the biologically active agent may be released at the site of placement. As an example, see U.S. Pat. No. 5,605,696 (Eury et al.). According to the present invention, novel methods for producing a stent have also been developed. A first such method, as shown in FIGS. 1-3 and 5 , comprises machining a sheet of material 10 to create a leaving portion 11 and a stent-forming portion 12 , said stent-forming portion 12 comprising at least one flexible, serpentine backbone 2 and a plurality of opposing, outwardly-projecting appendages 3 on said backbone 2 , and then shaping said stent-forming portion 12 to have a substantially circular cross-section, thereby forming said stent 1 . Thus, according to this first method, one starts with a preferably planar sheet of material 10 , as best seen in FIG. 1 (which shows the pattern where the leaving portion 11 and the stent-forming portion 12 will be machined). The sheet of material 10 can be machined in any of a variety of ways, including laser-cutting, photo-chemical etching (discussed in more detail below), mechanical cutting, other mechanical methods, and the like. The machining process separates the sheet of material 10 into the leaving portion 11 , which is typically recycled, and the stent-forming portion 12 , which is further processed to create the stent 1 . The partially-formed stent 1 , as seen in FIG. 2, is next processed by bending the backbone 2 thereof in order to introduce the necessary curves or corners. This may be done by any means now known or later developed by those of skill in the art. It is also possible to avoid this bending step entirely by machining the sheet of material 10 such that the backbone 2 of the stent-forming portion 12 is already serpentine at the conclusion of the machining step. An alternative embodiment of the present invention is seen in FIG. 4 . In this embodiment, the stent 1 has two backbones, the serpentine backbone 2 as previously described, and a linear backbone 6 . The advantages of adding the linear backbone 6 include increased structural integrity, minimization of length changes upon deployment, and the like. In a modification of this embodiment, the linear backbone 6 is discontinuous. By discontinuous it is meant that the linear backbone 6 is comprised of a series of physically separate linear pieces connecting consecutive portions of the serpentine backbone 2 , but not every consecutive portion. This modification results in a stent having properties that are typically intermediate between the embodiment shown in FIG. 4, and that of FIG. 3 . The linear backbone 6 may be added to the stent 1 in many ways. The simplest and preferred method is to perform the machining step such that the serpentine backbone 2 and the linear backbone 6 are produced simultaneously. The main advantage of this method is the fact that the integral nature of the stent 1 is maintained. A second method is to weld or otherwise adhere the linear backbone 6 to the partially formed stent as seen in FIG. 3 . The final step in forming the stent 1 is the curling of the partially formed stent 1 (as seen in FIG. 3 or 4 ) into a cylindrical or frustoconical shape, thus forming the finished stent 1 . There are many methods of performing this step that are well known to those of skill in the art, any of which will suffice. Another step that is preferably performed is the machining of the sheet of material 10 to include cavities 5 in the stent-forming portion 12 . This step may be performed in a wide variety of ways, e.g., by laser, chemical, or mechanical means known to those of skill in the art, and the like. Although this step may be performed at any time, it is presently preferred to machine the cavities 5 in the sheet of material 10 prior to any other production step. However, the formation of the cavities 5 may be done at any stage of production, if desired. A preferred method of machining the sheet of material 10 to create the leaving portion 11 and the stent-forming portion 12 is photochemical etching, comparable to the techniques used in the microchip industry. The first step in this method is to coat the sheet of material 10 with a layer of photoresist or similar such coating compound. Next, a template with the design of the stent 1 is placed over the sheet of material 10 . Then, the photoresist is removed from those areas not covered by the template. This is preferably done by laser, although other techniques are well known to those of skill in the art. Finally, the sheet of material 10 is chemically etched or chemically milled, thereby removing the leaving portion 11 and creating the stent-forming portion 12 . In an alternative method for producing a stent 1 according to the present invention, a tube of material can be machined to create a leaving portion and a stent-forming portion, which are similar in nature to the leaving portion 11 and the stent-forming portion 12 as discussed above. The major difference in this method is that the final forming step is not required, as the tubular nature of the starting material means that the stent 1 is in finished form as soon as the leaving portion is removed. Just as above, using this method, the stent-forming portion comprises at least one flexible, serpentine backbone 2 and a plurality of opposing, outwardly-projecting appendages 3 on the backbone 2 . In another alternative method for producing a stent 1 according to the present invention, a length of wire can be wrapped around appropriately placed guideposts to create a pre-stent comprising at least one flexible, serpentine backbone 2 and a plurality of opposing, outwardly-projecting appendages 3 on the backbone 2 . Then, the pre-stent is shaped to have a substantially circular cross-section, thereby forming the stent 1 . As discussed above, memory metals such as nitinol may be used to produce a stent according to the invention. As such, it is useful to set the memory of the metal to a specific shape at some point during manufacture. This is preferably done by heat-treating the metal. Once the metal is in the desired shape, it is subjected to heat of about 980±20° F., for about one to five hours. This is typically sufficient to adjust the crystal lattice of the metal and thereby set the memory. Of course, other temperatures, for different periods of time, may be desirable for memory metals other than nitinol. In accordance with another embodiment of the present invention, there are provided methods for delivering a biologically active agent to a patient, comprising inserting the stent 1 according to the present invention (specifically, those embodiments that include cavities 5 ) into a vessel of the patient. While the invention has been described in detail with reference to certain preferred embodiments thereof, it will be understood that modifications and variations are within the spirit and scope of that which is described and claimed.
A stent having cavities has been developed that can be quickly and easily used in a wide variety of situations, that keeps vessels open with a minimum degree of recoil and shortening lengthwise, that is flexible and can be delivered to the most distal lesion, and that can continuously deliver anticoagulant or other biologically active agents for an extended period directly at the site of stent placement. The stent of the present invention includes at least one flexible, serpentine backbone, and a plurality of opposing, outwardly-projecting appendages on said backbone, wherein said stent has a substantially circular cross-section.
Summarize the key points of the given document.
[ "FIELD OF THE INVENTION The present invention relates to stents having cavities capable of incorporating biologically active agents therein.", "More particularly, the present invention relates to stents that are highly flexible, easily used in a wide variety of situations, and that can continuously deliver diagnostic and/or therapeutic agents for an extended period directly at the site of stent placement.", "In another aspect, the present invention relates to methods of making stents having such properties.", "Stents according to the present invention are especially useful for vascular treatment.", "BACKGROUND OF THE INVENTION Cardiovascular disease, including atherosclerosis, is the leading cause of death in the United States.", "The medical community has developed a number of methods for treatment of coronary heart disease, some of which are specifically designed to treat complications resulting from atherosclerosis and other forms of coronary arterial narrowing.", "In another form, arterial wall degeneration with the formation of aneurysms causes arterial wall thinning.", "Management of the dilated arteries in the peripheral circulation has come under the domain of vascular surgeons.", "Investigators in the field of vascular surgery had at one time handled both narrowed and dilated arteries by techniques for suture anastomosis (sewing together) of two arterial segments using needle and thread.", "Today, there is a significantly less invasive clinical approach known as endovascular grafting.", "However, the most compelling development in the past decade is percutaneous transluminal coronary angioplasty (PTCA, or simply “angioplasty”).", "The objective in angioplasty is to enlarge the lumen of the affected coronary artery by radial hydraulic expansion.", "The procedure is accomplished by inflating a balloon within the narrowed lumen of the coronary artery.", "Radial expansion of the coronary artery occurs in several different dimensions and is related to the nature of the plaque.", "Soft, fatty plaque deposits are flattened by the balloon and hardened deposits are cracked and split to enlarge the lumen.", "The wall of the artery itself is stretched when the balloon is inflated.", "PTCA is performed as follows: A thin walled, hollow guiding catheter is typically introduced into the body via a relatively large vessel, such as the femoral artery in the groin area or the brachial artery in the arm.", "Access to the femoral artery is achieved by introducing a large bore needle directly into the femoral artery, a procedure known as the Seldinger technique.", "Once access to the femoral artery is achieved, a short hollow sheath is introduced to maintain a passageway during PTCA.", "The flexible guiding catheter, which is typically polymer coated, and lined with Teflon™, is inserted through the sheath into the femoral artery.", "The guiding catheter is advanced through the femoral artery into the iliac artery and into the ascending aorta.", "Further advancement of the flexible catheter involves the negotiation of an approximately 180 degree turn through the aortic arch to allow the guiding catheter to descend into the aortic cusp where entry may be gained to either the left or the right coronary artery as desired.", "After the guiding catheter is advanced to the ostium of the coronary artery to be treated by PTCA, a flexible guidewire is inserted into the guiding catheter through a balloon and advanced to the area to be treated.", "The guide wire provides the necessary steerability for lesion passage.", "The guidewire is advanced across the lesion, or “wires”", "the lesion, in preparation for the advancement of the balloon catheter across the guide wire.", "The balloon, or dilatation, catheter is placed in position by sliding it along the guide wire.", "The use of a relatively rigid guide wire is necessary to advance the catheter through the narrowed lumen of the artery and to direct the balloon, which is typically quite flexible, across the lesion.", "Radiopaque markers in the balloon segments of the catheter facilitate positioning across the lesion.", "The balloon catheter is then inflated with contrast material to permit fluoroscopic viewing during treatment.", "The balloon is alternately inflated and deflated until the lumen of the artery is satisfactory enlarged.", "By way of example, further details of angioplasty procedures and devices used in such procedures can be found in U.S. Pat. No. 4,327,071 (Simpson et al.), U.S. Pat. No. 4,332,254 (Lundquist), U.S. Pat. No. 4,439,185 (Lundquist), U.S. Pat. No. 4,468,224 (Enzmann et al.), U.S. Pat. No. 4,516,972 (Samson), U.S. Pat. No. 4,582,181 (Samson), U.S. Pat. No. 4,748,982 (Horzewski et al.), U.S. Pat. No. 4,771,778 (Mar), and U.S. Pat. No. 4,793,350 (Mar et al.), each of which is hereby incorporated by reference herein.", "A common problem that sometimes occurs after an angioplasty procedure is the appearance of restenosis at or near the site of the original stenosis in the blood vessel, which requires a secondary angioplasty procedure or bypass surgery.", "Another occurrence which reduces the success of angioplasty procedures is the collapse of a section of the dissected lining (commonly termed a “flap”) into the blood stream upon deflation of the balloon, thereby closing or significantly reducing the blood flow through the vessel.", "In this instance, emergency bypass surgery is sometimes required to avoid a myocardial infarct distal blockage.", "On some occasions, the dilatation catheter can be replaced with a perfusion type dilatation catheter such as described in U.S. Pat. No. 4,790,315 (Mueller, Jr. et al.) in order to hold the blood vessel open for extended periods.", "However, perfusion type dilatation catheters have relatively large profiles which can make advancement thereof through the blockage difficult, and therefore immediate bypass surgery may be the only means of avoiding an infarct distal to the blockage or possibly even death.", "Additionally, the inflated balloon of these perfusion catheters can block off a branch artery, thus creating ischemic conditions in the side branch distal to the blockage.", "In recent years, various devices and methods for prevention of restenosis and repairing damaged blood vessels have been developed which typically use an expandable cage or region commonly termed a “stent”", "which is placed on the distal end of a catheter, and is designed to hold a detached lining against an arterial wall for extended periods to facilitate the reattachment thereof.", "Stents are generally cylindrically shaped intravascular devices which in some cases can also be used as the primary treatment devices where they are expanded to dilate a stenosis and then left in place.", "Various types of stents and stent delivery systems are disclosed in U.S. Pat. No. 3,868,956 (Alfidi et al.), U.S. Pat. No. 4,503,569 (Dotter), U.S. Pat. No. 4,512,338 (Balko et al.), U.S. Pat. No. 4,553,545 (Maass et al.), U.S. Pat. No. 4,655,771 (Wallsten), U.S. Pat. No. 4,665,918 (Garza et al.), U.S. Pat. No. 4,733,665 (Palmaz), U.S. Pat. No. 4,795,458 (Regan), U.S. Pat. No. 4,800,882 (Gianturco), U.S. Pat. No. 4,830,003 (Wolff et al.), U.S. Pat. No. 4,856,516 (Hillstead), U.S. Pat. No. 4,878,906 (Lindemann et al.), U.S. Pat. No. 4,886,062 (Wiktor), U.S. Pat. No. 4,907,336 (Gianturco), U.S. Pat. No. 5,201,757 (Heyn et al.), U.S. Pat. No. 5,234,457 (Andersen), U.S. Pat. No. 5,292,331 (Boneau), U.S. Pat. No. 5,314,444 (Gianturco), U.S. Pat. No. 5,344,426 (Lau et al.), U.S. Pat. No. 5,372,600 (Beyar et al.), U.S. Pat. No. 5,387,235 (Chuter), U.S. Pat. No. 5,449,373 (Pinchasik et al.), U.S. Pat. No. 5,540,712 (Kleshinski et al.), U.S. Pat. No. 5,549,662 (Fordenbacher), U.S. Pat. No. 5,591,197 (Orth et al.), U.S. Pat. No. 5,593,434 (Williams), U.S. Pat. No. 5,599,576 (Opolski), U.S. Pat. No. 5,607,467 (Froix), U.S. Pat. No. 5,603,721 (Lau et al.), U.S. Pat. No. 5,605,530 (Fischell et al.), U.S. Pat. No. 5,382,261 (Palmaz), U.S. Pat. No. 5,549,635 (Solar), U.S. Pat. No. 5,500,013 (Buscemi et al.), U.S. Pat. No. 5,234,456 (Silvestrini), U.S. Pat. No. 5,342,348 (Kaplan), U.S. Pat. No. 5,368,566 (Crocker), U.S. Pat. No. 5,383,928 (Scott et al.), U.S. Pat. No. 5,423,885 (Williams), U.S. Pat. No. 5,443,458 (Eury), U.S. Pat. No. 5,464,450 (Buscemi et al.), U.S. Pat. No. 5,464,650 (Berg et al.), U.S. Pat. No. 5,618,299 (Khosravi et al.), U.S. Pat. No. 5,637,113 (Tartaglia et al.), U.S. Pat. No. 5,649,977 (Campbell), U.S. Pat. No. 5,419,760 (Narciso, Jr.), U.S. Pat. No. 5,651,174 (Schwartz et al.), and U.S. Pat. No. 5,556,413 (Lam), each of which is hereby incorporated by reference herein.", "See especially U.S. Pat. No. 4,800,882 to Gianturco, U.S. Pat. No. 5,234,457 to Andersen, U.S. Pat. No. 4,856,516 to Hillstead, and U.S. Pat. No. 5,500,013 to Buscemi et al.", "Because it is of utmost importance to avoid thrombosis of the stent and its serious complications, patients who receive stents are often aggressively treated with anticoagulants such as heparin, aspirin, coumadin, dextran, and/or persantine.", "As expected, there is a high incidence of bleeding complications in these patients.", "A study performed at Emory University Hospital revealed that 33% of the patients who received stents for acute closure required transfusion, and 7% of the patients had an extremely large bleeding episode at the catheter entry site in the leg artery that necessitated surgical repair (Hearn et al.", ", J. Am.", "Coll.", "Cardiol.", ", (1992).", "Because of the complications associated with systemic treatment with anticoagulants, extensive attempts have been made to desing a stent that would be non-thrombogenic.", "A stent with little or no propensity to form thrombus would drastically decrease the need for aggressive treatment with anticoagulants.", "Initially, stents were constructed of plastic.", "Because all of these stents caused thrombosis, stainless steel was then tried.", "These stents appeared promising in studies in canine peripheral arteries.", "However, most coronary stents used to date in clinical trials are composed of stainless steel and yet still have a thrombotic occlusion rate of approximately 5-30%.", "Tantalum is another metal that is used in stents.", "Although initial reports of a lower thrombogenicity of tantalum stents appeared promising (van der Giessen et al.", ", Circulation, 80:II-173 (1989)), more careful study has shown that tantalum is as thrombogenic as stainless steel (de Jaegere et al.", ", Amer.", "J. Cardiol.", ", 69:598-602 (1992)).", "The concept of coating a stent with a polymer was described several years ago and is discussed in the literature regularly.", "In the past, local delivery of drug(s) using stents has centered around two concepts: (1) directly coating the stent wires with a drug or a drug-polymer combination (Bailey et al.", ", Circulation, 82:III-541 (1990);", "and Cavendar et al.", ", Circulation, 82:III-541 (1990));", "and (2) incorporating a drug into a stent that is constructed of a biodegradable polymer (Murphy et al.", ", J. Invasive Cardiol.", ", 3:144-48 (1991)).", "Most investigators and stent companies have focussed their efforts on directly coating the metal stent wires with a polymer.", "This polymer is usually placed directly on the stent (e.g., by dipping the stent in soluble polymer) or is covalently bound to the metal.", "The polymer is bonded to or contains an anticoagulant compound most coated stents currently under development use heparin as their active agent.", "One of the more effective polymer coatings for stents is Biogold (van der Giessen, Circulation, 82:III-542 (1990)).", "Significant difficulties have been encountered with all prior art stents.", "Each has its percentage of thrombosis, restenosis, and tissue in-growth problems, as well as various degrees of difficulty of deployment.", "Another difficulty is that many prior art stents do not conform well to the vessel lumen.", "Some prior art stents require administration of anticoagulant medication to the patient for up to three months following their placement inside the body.", "What has been needed and heretofore unavailable in the art is a stent that can be quickly and easily used in a wide variety of situations, that keeps the vessel open with a minimum degree of recoil and shortening lengthwise, that is flexible and can be delivered to the most distal lesion, and that can continuously deliver anticoagulant or other biologically active agents for an extended period directly at the site of stent placement.", "SUMMARY OF THE INVENTION The present invention fills the above-described needs in the art by providing a stent that can be quickly and easily used in a wide variety of situations, that keeps the vessel open with a minimum degree of recoil and shortening lengthwise, that is flexible and can be delivered to the most distal lesion, and that can continuously deliver biologically active agents for an extended period directly at the site of stent placement.", "The present invention substantially reduces the complications and overcomes the limitations of prior art devices.", "In accordance with the present invention, there are provided flexible stents that can be delivered through a curved body conduit using a routine medical procedure and a conventional stent delivery system.", "Stents produced according to the present invention do not cause significant thrombosis at the point of implant, nor do they cause significant restenosis after implantation.", "Thus, the present invention provides stents that have superior performance characteristics, as well as certain production advantages, as compared to prior art devices.", "Therefore, the articles and methods of the present invention are extremely useful in coronary artery balloon angioplasty, as well as related medical procedures where it is useful to provide a stent to any body lumen.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a sheet of material to be used to form a stent according to the present invention, wherein the pattern of material to be removed is shown.", "FIG. 2 is a plan view of a partially-formed stent according to one embodiment the present invention, wherein the appropriate portions of the sheet of material have been removed.", "FIG. 3 is a plan view of a partially-formed stent according to one embodiment the present invention, wherein the partially-formed stent of FIG. 2 has been bent to create the serpentine backbone, and the cavities have been added.", "FIG. 4 is a plan view of an alternative embodiment of the partially-formed stent of FIG. 3, further including a secondary backbone in addition to the serpentine backbone.", "FIG. 5 is an elevation view of a stent according to the present invention, prior to placement and expansion within a body lumen.", "FIG. 6 is an elevation view of the stent of FIG. 5 as it would appear after placement and expansion.", "DETAILED DESCRIPTION OF THE INVENTION The above features and advantages of the present invention, as well as others are accomplished by providing a stent comprising a flexible, serpentine backbone and a plurality of cavities capable of incorporating biologically active agents therein.", "Also provided according to the present invention is a stent comprising at least one flexible, serpentine backbone and a plurality of opposing, outwardly-projecting appendages on said backbone;", "wherein said stent has a substantially circular cross-section.", "Also provided according to the present invention is a method of producing a stent, said method comprising machining a sheet of material to create a leaving portion and a stent-forming portion, said stent-forming portion comprising at least one flexible, serpentine backbone and a plurality of opposing, outwardly-projecting appendages on said backbone, and shaping said stent-forming portion to have a substantially circular cross-section, thereby forming said stent.", "Also provided according to the present invention is another method of producing a stent, said method comprising wrapping a length of wire around appropriately placed guideposts to create a pre-stent comprising at least one flexible, serpentine backbone and a plurality of opposing, outwardly-projecting appendages on said backbone, fastening the base of each of said appendages to said backbone, and shaping said pre-stent to have a substantially circular cross-section, thereby forming said stent.", "Also provided according to the present invention is still another method of producing a stent, said method comprising machining a tube of material to create a leaving portion and a stent-forming portion, said stent-forming portion comprising at least one flexible, serpentine backbone and a plurality of opposing, outwardly-projecting appendages on said backbone.", "While the primary application for stents according to the invention is presently treatment of cardiovascular disease such as atherosclerosis or other forms of coronary narrowing, stents according to the present invention may also be used for treatment of narrowing vessels in kidney lumens, respiratory lumens, urogenital lumens, bileducts, or elsewhere in the body.", "In such other vessels, the size of the stent may be adjusted to compensate for differing sizes of the vessel to be treated.", "Referring first to FIG. 5, one embodiment of a stent according to the invention is shown.", "A stent 1 comprises a semi-rigid, serpentine backbone 2 on which is attached several appendages 3 .", "The dimensions and shape of the stent 1 can vary dramatically.", "Of course, a major factor in selecting stent size is the intended biological use thereof.", "Obviously, the dimensions of the body lumen into which the stent 1 will be placed is a primary factor in determining the preferred shape and size.", "However, generally speaking, it is preferred that the stent 1 have a circular cross-section throughout its length.", "Additionally, it is usually simplest and best if the stent 1 is generally.", "cylindrical in shape.", "In another preferred alternative embodiment, the stent 1 is frustoconical (i.e., lampshade-shaped), as this enables the stent 1 to be introduced into a body lumen narrow-end-first, thus allowing for easier transluminal movement of the stent 1 .", "Of course, those of skill in the art can develop many alternative shapes that can be used as well.", "It is generally preferred that the stent 1 has a length of about 6 mm to about 200 mm.", "In a more preferred embodiment, the stent 1 has a length of about 10 mm to about 25 mm.", "In a most preferred embodiment (especially with respect to vascular placement), the stent 1 has a length of about 12 mm to about 18 mm.", "Although the stent 1 may be formed by first creating the backbone 2 and then attaching the appendages 3 thereto, it is presently preferred that the stent 1 be integrally formed from a single piece of material.", "By integrally formed, it is meant that the stent 1 is made from a single and continuous piece, sheet, tube, or other starting form of material, with no welds, adhesives, or other non-integral forms of attachment being used.", "Stents according to the present invention may be formed of a variety of materials that have the appropriate characteristics of formability, strength, flexibility, melting point, and non-reactivity with biological components.", "Thus, preferred materials for construction of a stent according to the invention are MP-35N, nitinol, ELGILOY™, platinum, platinum-tungsten, platinum-nickel, platinum-rhenium, stainless steel, gold, tantalum, titanium aluminide, polyurethane, silicone elastomers, polytetrafluoroethylene, combinations thereof, and the like.", "Presently, MP-35N is the most preferred material for construction of a stent according to the invention.", "Although the backbone 2 is shown in FIG. 5 as having a shape similar to a regular, repeating sine-wave, it may be of many different shapes and still be within the scope of the present invention.", "The advantage of the serpentine backbone 2 , as contrasted with comparable elements in prior art devices, is its non-linear and therefore more flexible shape.", "By being non-linear, the backbone 2 has a plurality of built-in flex points.", "These flex points, and the resulting increase in flexibility, enhance the ability of the doctor to transluminally move a stent according to the invention through tortuous anatomy to the desired site of use.", "Thus, in addition to the regular sine-wave shape seen in FIG. 5, backbone 2 may also have successive curves or waves in a non-regular pattern (i.e., successive waves having variances in frequency and/or amplitude, in repeating or non-repeating patterns), successive corners of varying angles in repeating or non-repeating patterns, combinations of curves and corners, or the like.", "Because the backbone 2 is non-linear, its length, as measured along the curve, is greater than the length of the stent 1 itself.", "In a preferred embodiment, the length of the backbone 2 , as measured along the curve thereof, is about 1.5 to about 4 times longer than the stent 1 .", "In a most preferred embodiment, the length of the backbone 2 , as measured along the curve thereof, is about 2 to about 3 times longer than the stent 1 .", "While the backbone 2 is required to support the appendages 3 , it is the appendages 3 that actually do the work of supporting the vessel into which the stent 1 is placed.", "The appendages 3 may be in a wide variety of shapes and sizes sufficient to support the vessel.", "It is generally preferred that the appendages 3 have a relatively large hole 4 therein, as can be clearly seen in FIG. 5 .", "By having a large hole 4 in each appendage 3 , the appendages 3 as a group can effectively support a larger surface area of the lumen, while not completely covering the tissue at that surface.", "Additionally, in preferred embodiments the appendages 3 are loop-shaped, rectangular, square-wave-shaped, teardrop-shaped, trapezoidal, rhomboidal, combinations thereof, or the like.", "In a presently preferred embodiment, the appendages 3 are loop-shaped.", "As mentioned above, while a variety of sizes are possible, and the preferred size of the appendages 3 depends mostly upon the size of the lumen in which the stent 1 will be used, it is generally preferred that the appendages 3 have a length of about 5 mm to about 200 mm, and a width of about 0.5 mm to about 5 mm.", "In a presently preferred embodiment, the appendages 3 have a length of about 0.5 mm to about 5 mm and a width of about 0.5 mm to about 4 mm.", "While not required, it is preferred that the appendages 3 be present down the entire length of the stent 1 .", "It is generally preferred that each stent 1 includes about 5 to about 40 appendages thereon.", "In a presently preferred embodiment, each stent 1 includes about 10 to about 20 appendages thereon.", "Thus, it is generally preferred that the distance between each of the appendages 3 on a single stent 1 is about 0.1 mm to about 1.5 mm.", "Because the appendages 3 do not interconnect to one another, they can be seen to permit the stent 1 to be compressed or expanded over a wide range of diameters while still maintaining the significant mechanical force required to prevent a vessel from recoiling or collapsing.", "While it is generally preferred that there be some degree of overlap between the appendages 3 extending from each side of the stent 1 (see FIG. 5) when the stent 1 is either expanded or contracted, this is not an absolute requirement.", "The degree of radial compliance of a stent will be dependent upon the strength of the metal alloy, the thickness of the stent strud, the proximity of successive appendages (i.e., the inter-appendage interval), and the angle of orientation of the appendages.", "In the presently preferred embodiment, the stent according to the present invention includes a plurality of cavities 5 thereon, as seen in FIG. 4 .", "The cavities are essentially relatively small holes or craters in the stent that may be filled with a biologically active agent or biologically active agent-containing formulation.", "By pre-filling the cavities with a biologically active agent prior to placement of the stent, the biologically active agent will be released into the patient after placement.", "Because the biologically active agent will be released at the site of placement, the biologically active agent can have its greatest effects directly at the desired location, without prior dilution throughout the body of the patient.", "Preferably, each stent 1 will include about 8 to about 400 cavities 5 .", "While the cavities 5 may be of almost any three-dimensional size or shape, in a preferred embodiment the cavities 5 are essentially hemispherical, slit-like, cubical, rectangular, teardrop-shaped, or the like.", "In a presently preferred embodiment, the cavities 5 are essentially circular in shape.", "The size of the cavities 5 is relatively unimportant, as long as the cavities 5 are large enough to hold the desired amount of biologically active agent.", "However, it is presently preferred that each of the cavities 5 has a volume of about 0.02 mm 3 to about 4 mm 3 .", "The cavities 5 may contain any desired biologically active agent.", "The term “biologically active agent”", "is used herein in an extremely expansive sense, and generally indicates any biologically active or diagnostically useful substance, including drugs, radioactive chemicals, gene therapy vectors, and the like.", "Exemplary drugs for use in the present invention are heparin, tissue plasminogen activator, coumadin, protamine, urokinase, hirudin, argatroban, forskolin, vapiprost, prostacyclin, prostacyclin analogues, dextran, D-phe-pro-arg-chloromethylketone, dipyridamole, glycoprotein IIb/IIIa platelet membrane receptor antibody, angiopeptin, angiotensin converting enzyme inhibitors, (such as Captopril™, Cilazapril™, Lisinopril™), calcium channel blockers, colchicine, fibroblast growth factor antagonists, fish oil, omega 3-fatty acids, histamine antagonists, HMG-CoA reductase inhibitor, methotrexate, azathioprine, vincristine, vinblastine, fluorouracil, adriamycin, mutamycin, monoclonal antibodies, nitroprusside, phosphodiesterase inhibitors, prostaglandin inhibitor, seramin, serotonin blockers, steroids, thioprotease inhibitors, triazolopyrimidine and other PDGF antagonists, alpha-interferon, glucocorticoids, dexamethasone, betamethasone, tocopherol, aspirin, ticlopdine, ACA inhibitors, growth factors, oligonucleotides, antimitotic agents, antioxidants, antimetabolite agents, phosphorylcholine, antibiotics, anti-inflammatories, narcotics, anti-platelet drugs, cytostatic agents, antiproliferative agents, and the like.", "Exemplary radioactive chemicals include iridium, cesium, cobalt, and any other elements or compounds that contain radioactive isotopes.", "Presently, the most preferred biologically active agents are those that serve as anti-thrombus agents and/or anti-restenosis agents, as these are the most desirable biologically active agents for localization to the site of placement (when the stent 1 is used intravascularly).", "The biologically active agent, or any formulation, containing the same, may be introduced into the cavities 5 by any suitable means known to those skilled in the art.", "For example, the stent 1 may be dipped into or otherwise coated with a liquid that includes the biologically active agent such that the liquid is drawn into the cavities 5 by surface tension affects.", "The liquid may subsequently be dried, or not, as desired.", "Alternatively, a biologically active agent in powder form may be “rubbed”", "into the cavities 5 .", "As another alternative, the biologically active agent may be combined with a polymeric material having controlled-release properties, and each of the cavities 5 carefully filled with this mixture.", "Many other alternatives will occur to those of skill in the art.", "Furthermore, the biologically active agent may be added to the cavities 5 either as part of the manufacturing process, or immediately prior to placement of the stent 1 in a body lumen.", "In one embodiment, the cavities 5 do not extend through the entire thickness of the stent 1 .", "In this case, the cavities 5 might be best described as craters, as opposed to holes.", "In such embodiments, the cavities 5 may be present on only an inner surface of the stent 1 , on only an outer surface of the stent 1 , or both surfaces simultaneously.", "When the stent 1 has cavities 5 on both its inner surface and outer surface, the stent 1 may contain a first biologically active agent in those cavities 5 on the inner surface, and a second biologically active agent in those cavities 5 on the outer surface.", "In such an embodiment, it is preferred that the first biologically active agent is an anti-thrombus agent, and the second biologically active agent is an anti-restenosis drug.", "Instead of, or in addition to, the use of cavities 5 , the stent according to the present invention may include a biologically active agent-impregnated polymeric material coating all or a portion of the appendages 3 .", "As is known to those of skill in the art, a wide variety of polymeric materials can either be formed with a releasable biologically active agent therein, or a biologically active agent may be absorbed by the polymeric material after its formation.", "By coating the appendages 3 with such a biologically active agent-impregnated polymeric material prior to placement inside a biological lumen, the biologically active agent may be released at the site of placement.", "As an example, see U.S. Pat. No. 5,605,696 (Eury et al.).", "According to the present invention, novel methods for producing a stent have also been developed.", "A first such method, as shown in FIGS. 1-3 and 5 , comprises machining a sheet of material 10 to create a leaving portion 11 and a stent-forming portion 12 , said stent-forming portion 12 comprising at least one flexible, serpentine backbone 2 and a plurality of opposing, outwardly-projecting appendages 3 on said backbone 2 , and then shaping said stent-forming portion 12 to have a substantially circular cross-section, thereby forming said stent 1 .", "Thus, according to this first method, one starts with a preferably planar sheet of material 10 , as best seen in FIG. 1 (which shows the pattern where the leaving portion 11 and the stent-forming portion 12 will be machined).", "The sheet of material 10 can be machined in any of a variety of ways, including laser-cutting, photo-chemical etching (discussed in more detail below), mechanical cutting, other mechanical methods, and the like.", "The machining process separates the sheet of material 10 into the leaving portion 11 , which is typically recycled, and the stent-forming portion 12 , which is further processed to create the stent 1 .", "The partially-formed stent 1 , as seen in FIG. 2, is next processed by bending the backbone 2 thereof in order to introduce the necessary curves or corners.", "This may be done by any means now known or later developed by those of skill in the art.", "It is also possible to avoid this bending step entirely by machining the sheet of material 10 such that the backbone 2 of the stent-forming portion 12 is already serpentine at the conclusion of the machining step.", "An alternative embodiment of the present invention is seen in FIG. 4 .", "In this embodiment, the stent 1 has two backbones, the serpentine backbone 2 as previously described, and a linear backbone 6 .", "The advantages of adding the linear backbone 6 include increased structural integrity, minimization of length changes upon deployment, and the like.", "In a modification of this embodiment, the linear backbone 6 is discontinuous.", "By discontinuous it is meant that the linear backbone 6 is comprised of a series of physically separate linear pieces connecting consecutive portions of the serpentine backbone 2 , but not every consecutive portion.", "This modification results in a stent having properties that are typically intermediate between the embodiment shown in FIG. 4, and that of FIG. 3 .", "The linear backbone 6 may be added to the stent 1 in many ways.", "The simplest and preferred method is to perform the machining step such that the serpentine backbone 2 and the linear backbone 6 are produced simultaneously.", "The main advantage of this method is the fact that the integral nature of the stent 1 is maintained.", "A second method is to weld or otherwise adhere the linear backbone 6 to the partially formed stent as seen in FIG. 3 .", "The final step in forming the stent 1 is the curling of the partially formed stent 1 (as seen in FIG. 3 or 4 ) into a cylindrical or frustoconical shape, thus forming the finished stent 1 .", "There are many methods of performing this step that are well known to those of skill in the art, any of which will suffice.", "Another step that is preferably performed is the machining of the sheet of material 10 to include cavities 5 in the stent-forming portion 12 .", "This step may be performed in a wide variety of ways, e.g., by laser, chemical, or mechanical means known to those of skill in the art, and the like.", "Although this step may be performed at any time, it is presently preferred to machine the cavities 5 in the sheet of material 10 prior to any other production step.", "However, the formation of the cavities 5 may be done at any stage of production, if desired.", "A preferred method of machining the sheet of material 10 to create the leaving portion 11 and the stent-forming portion 12 is photochemical etching, comparable to the techniques used in the microchip industry.", "The first step in this method is to coat the sheet of material 10 with a layer of photoresist or similar such coating compound.", "Next, a template with the design of the stent 1 is placed over the sheet of material 10 .", "Then, the photoresist is removed from those areas not covered by the template.", "This is preferably done by laser, although other techniques are well known to those of skill in the art.", "Finally, the sheet of material 10 is chemically etched or chemically milled, thereby removing the leaving portion 11 and creating the stent-forming portion 12 .", "In an alternative method for producing a stent 1 according to the present invention, a tube of material can be machined to create a leaving portion and a stent-forming portion, which are similar in nature to the leaving portion 11 and the stent-forming portion 12 as discussed above.", "The major difference in this method is that the final forming step is not required, as the tubular nature of the starting material means that the stent 1 is in finished form as soon as the leaving portion is removed.", "Just as above, using this method, the stent-forming portion comprises at least one flexible, serpentine backbone 2 and a plurality of opposing, outwardly-projecting appendages 3 on the backbone 2 .", "In another alternative method for producing a stent 1 according to the present invention, a length of wire can be wrapped around appropriately placed guideposts to create a pre-stent comprising at least one flexible, serpentine backbone 2 and a plurality of opposing, outwardly-projecting appendages 3 on the backbone 2 .", "Then, the pre-stent is shaped to have a substantially circular cross-section, thereby forming the stent 1 .", "As discussed above, memory metals such as nitinol may be used to produce a stent according to the invention.", "As such, it is useful to set the memory of the metal to a specific shape at some point during manufacture.", "This is preferably done by heat-treating the metal.", "Once the metal is in the desired shape, it is subjected to heat of about 980±20° F., for about one to five hours.", "This is typically sufficient to adjust the crystal lattice of the metal and thereby set the memory.", "Of course, other temperatures, for different periods of time, may be desirable for memory metals other than nitinol.", "In accordance with another embodiment of the present invention, there are provided methods for delivering a biologically active agent to a patient, comprising inserting the stent 1 according to the present invention (specifically, those embodiments that include cavities 5 ) into a vessel of the patient.", "While the invention has been described in detail with reference to certain preferred embodiments thereof, it will be understood that modifications and variations are within the spirit and scope of that which is described and claimed." ]
BACKGROUND [0001] The subject matter disclosed herein relates to elevator systems driven by coated steel belts. More specifically, the subject disclosure relates to sheave configurations for elevator systems driven by coated steel belts. [0002] Elevator systems utilize coated steel belts operably connected to an elevator car, and driven by a motor to propel the elevator car along a hoistway. Coated steel belts in particular include a plurality of wires located at least partially within a jacket material. The plurality of wires is often arranged into one or more strands and the strands are then arranged into one or more cords. In an exemplary belt construction, a plurality of cords is typically arranged equally spaced within a jacket in a longitudinal direction. [0003] The motor drives a sheave, in this case a traction sheave, over which the coated steel belt is routed. The belt gains traction at the traction sheave, such that rotation of the traction sheave consequently drives movement of the elevator car. The coated steel belt is then routed over one or more idler or deflector sheaves to guide the belt between the traction sheave and the elevator car. It is desired for the belt to travel, or track, over a center portion of the deflector sheave to evenly distribute tension in the belt cords and to prevent cords, especially end cords, of the belt from going into compression and buckling. One method to center the belt on the deflector sheave is to incorporate a crown into the sheave surface geometry. A further requirement for the deflector sheave, however, is a low surface coefficient of friction in order reduce sticking or slipping of the belt over the deflector sheave and thereby reducing associated noise. If the deflector sheave coefficient of friction is too low, however, the belt will not have enough lateral traction to climb and remain at the crown. BRIEF DESCRIPTION [0004] In one embodiment, a deflector sheave for an elevator system includes an outer sheave surface having a distance from a sheave axis that varies along a width of the traction sheave. The outer surface includes a first portion having a first coefficient of friction and one or more second portions having a second coefficient of friction less than the first coefficient of friction, the first portion guiding an elevator belt toward a lateral center of the outer surface. [0005] Additionally or alternatively in this or other embodiments, the first portion is positioned at a center area of the outer sheave surface relative to the width of the deflector sheave. [0006] Additionally or alternatively in this or other embodiments, the first portion comprises about 25% to 50% of the width of the traction deflector. [0007] Additionally or alternatively in this or other embodiments, the first coefficient of friction of the first portion is defined by an abrasive blast applied to the first portion. [0008] Additionally or alternatively in this or other embodiments, the second coefficient of friction of the one or more second portions is defined by masking the one or more second portions during the abrasive blast operation. [0009] Additionally or alternatively in this or other embodiments, the first coefficient of friction of the first portion is defined by a coating applied to the first portion. [0010] Additionally or alternatively in this or other embodiments, the one or more second portions are two second portions. [0011] Additionally or alternatively in this or other embodiments, each second portion comprises about 25% to 40% of the width of the deflector sheave. [0012] Additionally or alternatively in this or other embodiments, the second coefficient of friction of the one or more second portions is defined by a coating applied to the one or more second portions. [0013] Additionally or alternatively in this or other embodiments, the first coefficient of friction is defined by masking the first portion while applying the coating to the one or more second portions. [0014] Additionally or alternatively in this or other embodiments, the coating is a Teflon nickel coating. [0015] Additionally or alternatively in this or other embodiments, the first portion and the one or more second portions are formed by machined grooves in the outer surface of the deflector sheave. [0016] Additionally or alternatively in this or other embodiments, the outer sheave surface has a spherical crown. [0017] Additionally or alternatively in this or other embodiments, the spherical crown has a radius of between 250 mm and 1000 mm. [0018] Additionally or alternatively in this or other embodiments, the first coefficient of friction is greater than or equal to 0.1. [0019] n another embodiment, an elevator system includes an elevator car, a motor, and traction sheave operably connected to the motor to drive rotation of the traction sheave. A belt is operably connected to the elevator car and is in frictional contact with the traction sheave such that rotation of the traction sheave urges movement of the elevator car. One or more deflector sheaves are located between the traction sheave and the elevator car over which the belt is routed to guide the belt to the elevator car. The one or more deflector sheaves include an outer sheave surface having a distance from a sheave axis that varies along a width of the traction sheave. The outer surface includes a first portion having a first coefficient of friction and one or more second portions having a second coefficient of friction less than the first coefficient of friction, the first portion guiding an elevator belt toward a lateral center of the outer surface. [0020] Additionally or alternatively in this or other embodiments, the first portion is positioned at a center area of the outer sheave surface relative to the width of the deflector sheave. [0021] Additionally or alternatively in this or other embodiments, the first portion comprises about 25% to 50% of the width of the traction deflector. [0022] Additionally or alternatively in this or other embodiments, the first coefficient of friction of the first portion is defined by an abrasive blast applied to the first portion. [0023] Additionally or alternatively in this or other embodiments, the second coefficient of friction of the one or more second portions is defined by masking the one or more second portions during the abrasive blast operation. [0024] Additionally or alternatively in this or other embodiments, the first coefficient of friction of the first portion is defined by a coating applied to the first portion. [0025] Additionally or alternatively in this or other embodiments, the one or more second portions are two second portions. [0026] Additionally or alternatively in this or other embodiments, each second portion comprises about 25% to 40% of the width of the deflector sheave. [0027] Additionally or alternatively in this or other embodiments, the second coefficient of friction of the one or more second portions is defined by a coating applied to the one or more second portions. [0028] Additionally or alternatively in this or other embodiments, the first coefficient of friction is defined by masking the first portion while applying the coating to the one or more second portions. [0029] Additionally or alternatively in this or other embodiments, the coating is a Teflon nickel coating. [0030] Additionally or alternatively in this or other embodiments, the first portion and the one or more second portions are formed by machined grooves in the outer surface of the deflector sheave. [0031] Additionally or alternatively in this or other embodiments, the outer sheave surface has a spherical crown. [0032] Additionally or alternatively in this or other embodiments, the spherical crown has a radius of between 250 mm and 1000 mm. [0033] Additionally or alternatively in this or other embodiments, the first coefficient of friction is greater than or equal to 0.1. BRIEF DESCRIPTION OF THE DRAWINGS [0034] FIG. 1A is a schematic of an exemplary elevator system having a 1:1 roping arrangement; [0035] FIG. 1B is a schematic of another exemplary elevator system having a different roping arrangement; [0036] FIG. 1C is a schematic of another exemplary elevator system having a cantilevered arrangement; [0037] FIG. 2 is a cross-sectional view of an elevator belt; [0038] FIG. 3 is a cross-sectional view of a cord or rope; [0039] FIG. 4 is a view of an embodiment of a deflector sheave for an elevator system; [0040] FIG. 5 is a view of another embodiment of a deflector sheave for an elevator system; and [0041] FIG. 6 is a view of yet another embodiment of a deflector sheave for an elevator system. [0042] The detailed description explains the invention, together with advantages and features, by way of examples with reference to the drawings. DETAILED DESCRIPTION [0043] Shown in FIGS. 1A, 1B and 1C are schematics of exemplary traction elevator systems 10 . Features of the elevator system 10 that are not required for an understanding of the present invention (such as the guide rails, safeties, etc.) are not discussed herein. The elevator system 10 includes an elevator car 12 operatively suspended or supported in a hoistway 14 with one or more belts 16 . The one or more belts 16 interact with one or more deflector sheaves 18 to be routed around various components of the elevator system 10 . The one or more belts 16 could also be connected to a counterweight 22 , which is used to help balance the elevator system 10 and reduce the difference in belt tension on both sides of the traction sheave during operation. It is to be appreciated that while the embodiments herein are described as applied to coated steel belts, it is to be appreciated that the disclosure herein may similarly be applied to steel ropes, either coated or uncoated. [0044] The deflector sheaves 18 each have a diameter 20 , which may be the same or different than the diameters of the other deflector sheaves 18 in the elevator system 10 . At least one of the sheaves could be a traction sheave 24 . The traction sheave 24 is driven by a machine 26 . Movement of the traction sheave 24 by the machine 26 drives, moves and/or propels (through traction) the one or more belts 16 that are routed around the traction sheave 24 . [0045] In some embodiments, the elevator system 10 could use two or more belts 16 for suspending and/or driving the elevator car 12 . In addition, the elevator system 10 could have various configurations such that either both sides of the one or more belts 16 engage the one or more deflector sheaves 18 (such as shown in the exemplary elevator systems in FIGS. 1A, 1B or 1C ) or only one side of the one or more belts 16 engages the one or more sheaves 18 . [0046] FIG. 1A provides a 1:1 roping arrangement in which the one or more belts 16 terminate at the car 12 and counterweight 22 . FIGS. 1B and 1C provide different roping arrangements. Specifically, FIGS. 1B and 1C show that the car 12 and/or the counterweight 22 can have one or more deflector sheaves 18 thereon engaging the one or more belts 16 and the one or more belts 16 can terminate elsewhere, typically at a structure within the hoistway 14 (such as for a machineroomless elevator system) or within the machine room (for elevator systems utilizing a machine room). The number of deflector sheaves 18 used in the arrangement determines the specific roping ratio (e.g., the 2:1 roping ratio shown in FIGS. 1B and 1C or a different ratio). FIG. 1C also provides a cantilevered type elevator. The present invention could be used on elevator systems other than the exemplary types shown in FIGS. 1A, 1B and 1C . [0047] FIG. 2 provides a schematic of a belt construction or design. Each belt 16 is constructed of a plurality of wires 28 (e.g. twisted into one or more strands 30 and/or cords 32 as shown in FIG. 3 ) in a jacket 34 . As seen in FIG. 2 , the belt 16 has an aspect ratio greater than one (i.e. belt width is greater than belt thickness). The belts 16 are constructed to have sufficient flexibility when passing over the one or more deflector sheaves 18 to provide low bending stresses, meet belt life requirements and have smooth operation, while being sufficiently strong to be capable of meeting strength requirements for suspending and/or driving the elevator car 12 . The jacket 34 could be any suitable material, including a single material, multiple materials, two or more layers using the same or dissimilar materials, and/or a film. In one arrangement, the jacket 34 could be a polymer, such as an elastomer, applied to the cords 32 using, for example, an extrusion or a mold wheel process. In another arrangement, the jacket 34 could be a woven fabric that engages and/or integrates the cords 32 . As an additional arrangement, the jacket 34 could be one or more of the previously mentioned alternatives in combination. [0048] The jacket 34 can substantially retain the cords 32 therein. The phrase substantially retain means that the jacket 34 has sufficient engagement with the cords 32 to transfer torque from the machine 26 through the jacket 34 to the cords 32 to drive movement of the elevator car 12 . The jacket 34 could completely envelop the cords 32 (such as shown in FIG. 2 ), substantially envelop the cords 24 , or at least partially envelop the cords 32 . [0049] An exemplary deflector sheave 18 is shown in FIG. 4 . A sheave outer surface 38 includes a crown, in some embodiments a spherical crown, such that a sheave radius 40 from a sheave axis 42 to the sheave outer surface 38 is greater at a sheave center 44 of the deflector sheave 18 than at either sheave end 46 of the deflector sheave 18 . The crown configuration aids the belt 16 in being substantially centered on the sheave outer surface 38 between sheave ends 46 . As stated above, however, the crown of the deflector sheave 18 , in some embodiments a crown radius between 250 mm and 1000 mm, and the desire for low coefficient of friction of the deflector sheave 18 makes it difficult for the belt 16 to climb the crown of the deflector sheave 18 and remain centered. [0050] The deflector sheave 18 is uniquely configured to address the problems noted with prior art deflector sheaves. The deflector sheave 18 includes a high friction zone 48 and one or more low friction zones 50 , with the high friction zone 48 characterized as having a higher coefficient of friction than the low friction zones 50 . The high friction zone 48 is located, for example, around the sheave center 44 of the deflector sheave 18 , and in some embodiments includes about a center 25% to 50% of the sheave outer surface 38 . The high friction zone 48 is treated by abrasive blasting or other surface treatment or coating to provide a high friction surface to effectively guide the deflector sheave 18 up the crown of the deflector sheave 18 . The low friction zones 50 are located, for example, outboard of the high friction zone 48 and extend to the sheave ends 46 , and in some embodiments include about the outer 25% to 40% of the sheave outer surface 38 . The low friction zones 50 are characterized by having a lower coefficient of friction than the high friction sheave 48 . The lower coefficient of friction in the low friction zones 50 is achieved by, in some embodiments, applying a reduced-friction coating to the low friction zones 50 , for example, a Teflon nickel coating, an electroless nickel coating, a thin dense chrome coating, or a low friction plasma coating. In other embodiments, the lower coefficient of friction in the low friction zones 50 is achieved by masking the low friction zones 50 during the abrasive blast operation on the high friction zone 48 . It is to be appreciated that lower coefficient of friction in the low friction zones 50 may further be achieved via other means, for example, by the use of different materials to form the low friction zones 50 , relative to the high friction zone 48 . In some embodiments, the high friction zones 48 are defined as having a coefficient of friction greater than or equal to 0.1, while low friction zones 50 are defined as those having a coefficient of friction of less than 0.1. [0051] Referring now to FIG. 5 , in some embodiments, the deflector sheave 18 includes two or more high friction zones 48 arranged as bands in the deflector sheave 18 outer surface 38 . Further, in other embodiments, as shown in FIG. 6 , grooves 52 are formed in the outer surface 38 by, for example, machining. In some embodiments, the grooves 52 are as wide as a cord 32 of the belt 16 , are may be as small in width as 0.1 mm. A depth of the grooves 52 is determined by a depth required to introduce friction at edges of the grooves 52 between the edges of the grooves 52 and the belt 16 . In some embodiments, the groove depth, measured as a radial difference between a groove peak and a groove valley is between 0.1 mm and 1.0 mm. In other embodiments, the depth is between 0.25 mm and 0.5 mm. The groove peak may be positioned either radially above, below or at the outer surface 38 . In embodiments where the peak of the groove 52 is above or below the outer surface 38 , a radial distance between the peak and the outer surface is about 0.1 mm maximum to maintain tension balance of the belt 16 . [0052] While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
An elevator system includes an elevator car, a motor, and traction sheave operably connected to the motor to drive rotation of the traction sheave. A belt is operably connected to the elevator car and in frictional contact with the traction sheave to urge movement of the elevator car. One or more deflector sheaves are located between the traction sheave and the elevator car over which the belt is routed to guide the belt to the elevator car. The one or more deflector sheaves include an outer sheave surface having a distance from a sheave axis that varies along a width of the traction sheave. The outer surface includes a first portion having a first coefficient of friction and a second portion having a second coefficient of friction less than the first coefficient of friction, the first portion guiding an elevator belt toward a lateral center of the outer surface.
Identify the most important claim in the given context and summarize it
[ "BACKGROUND [0001] The subject matter disclosed herein relates to elevator systems driven by coated steel belts.", "More specifically, the subject disclosure relates to sheave configurations for elevator systems driven by coated steel belts.", "[0002] Elevator systems utilize coated steel belts operably connected to an elevator car, and driven by a motor to propel the elevator car along a hoistway.", "Coated steel belts in particular include a plurality of wires located at least partially within a jacket material.", "The plurality of wires is often arranged into one or more strands and the strands are then arranged into one or more cords.", "In an exemplary belt construction, a plurality of cords is typically arranged equally spaced within a jacket in a longitudinal direction.", "[0003] The motor drives a sheave, in this case a traction sheave, over which the coated steel belt is routed.", "The belt gains traction at the traction sheave, such that rotation of the traction sheave consequently drives movement of the elevator car.", "The coated steel belt is then routed over one or more idler or deflector sheaves to guide the belt between the traction sheave and the elevator car.", "It is desired for the belt to travel, or track, over a center portion of the deflector sheave to evenly distribute tension in the belt cords and to prevent cords, especially end cords, of the belt from going into compression and buckling.", "One method to center the belt on the deflector sheave is to incorporate a crown into the sheave surface geometry.", "A further requirement for the deflector sheave, however, is a low surface coefficient of friction in order reduce sticking or slipping of the belt over the deflector sheave and thereby reducing associated noise.", "If the deflector sheave coefficient of friction is too low, however, the belt will not have enough lateral traction to climb and remain at the crown.", "BRIEF DESCRIPTION [0004] In one embodiment, a deflector sheave for an elevator system includes an outer sheave surface having a distance from a sheave axis that varies along a width of the traction sheave.", "The outer surface includes a first portion having a first coefficient of friction and one or more second portions having a second coefficient of friction less than the first coefficient of friction, the first portion guiding an elevator belt toward a lateral center of the outer surface.", "[0005] Additionally or alternatively in this or other embodiments, the first portion is positioned at a center area of the outer sheave surface relative to the width of the deflector sheave.", "[0006] Additionally or alternatively in this or other embodiments, the first portion comprises about 25% to 50% of the width of the traction deflector.", "[0007] Additionally or alternatively in this or other embodiments, the first coefficient of friction of the first portion is defined by an abrasive blast applied to the first portion.", "[0008] Additionally or alternatively in this or other embodiments, the second coefficient of friction of the one or more second portions is defined by masking the one or more second portions during the abrasive blast operation.", "[0009] Additionally or alternatively in this or other embodiments, the first coefficient of friction of the first portion is defined by a coating applied to the first portion.", "[0010] Additionally or alternatively in this or other embodiments, the one or more second portions are two second portions.", "[0011] Additionally or alternatively in this or other embodiments, each second portion comprises about 25% to 40% of the width of the deflector sheave.", "[0012] Additionally or alternatively in this or other embodiments, the second coefficient of friction of the one or more second portions is defined by a coating applied to the one or more second portions.", "[0013] Additionally or alternatively in this or other embodiments, the first coefficient of friction is defined by masking the first portion while applying the coating to the one or more second portions.", "[0014] Additionally or alternatively in this or other embodiments, the coating is a Teflon nickel coating.", "[0015] Additionally or alternatively in this or other embodiments, the first portion and the one or more second portions are formed by machined grooves in the outer surface of the deflector sheave.", "[0016] Additionally or alternatively in this or other embodiments, the outer sheave surface has a spherical crown.", "[0017] Additionally or alternatively in this or other embodiments, the spherical crown has a radius of between 250 mm and 1000 mm.", "[0018] Additionally or alternatively in this or other embodiments, the first coefficient of friction is greater than or equal to 0.1.", "[0019] n another embodiment, an elevator system includes an elevator car, a motor, and traction sheave operably connected to the motor to drive rotation of the traction sheave.", "A belt is operably connected to the elevator car and is in frictional contact with the traction sheave such that rotation of the traction sheave urges movement of the elevator car.", "One or more deflector sheaves are located between the traction sheave and the elevator car over which the belt is routed to guide the belt to the elevator car.", "The one or more deflector sheaves include an outer sheave surface having a distance from a sheave axis that varies along a width of the traction sheave.", "The outer surface includes a first portion having a first coefficient of friction and one or more second portions having a second coefficient of friction less than the first coefficient of friction, the first portion guiding an elevator belt toward a lateral center of the outer surface.", "[0020] Additionally or alternatively in this or other embodiments, the first portion is positioned at a center area of the outer sheave surface relative to the width of the deflector sheave.", "[0021] Additionally or alternatively in this or other embodiments, the first portion comprises about 25% to 50% of the width of the traction deflector.", "[0022] Additionally or alternatively in this or other embodiments, the first coefficient of friction of the first portion is defined by an abrasive blast applied to the first portion.", "[0023] Additionally or alternatively in this or other embodiments, the second coefficient of friction of the one or more second portions is defined by masking the one or more second portions during the abrasive blast operation.", "[0024] Additionally or alternatively in this or other embodiments, the first coefficient of friction of the first portion is defined by a coating applied to the first portion.", "[0025] Additionally or alternatively in this or other embodiments, the one or more second portions are two second portions.", "[0026] Additionally or alternatively in this or other embodiments, each second portion comprises about 25% to 40% of the width of the deflector sheave.", "[0027] Additionally or alternatively in this or other embodiments, the second coefficient of friction of the one or more second portions is defined by a coating applied to the one or more second portions.", "[0028] Additionally or alternatively in this or other embodiments, the first coefficient of friction is defined by masking the first portion while applying the coating to the one or more second portions.", "[0029] Additionally or alternatively in this or other embodiments, the coating is a Teflon nickel coating.", "[0030] Additionally or alternatively in this or other embodiments, the first portion and the one or more second portions are formed by machined grooves in the outer surface of the deflector sheave.", "[0031] Additionally or alternatively in this or other embodiments, the outer sheave surface has a spherical crown.", "[0032] Additionally or alternatively in this or other embodiments, the spherical crown has a radius of between 250 mm and 1000 mm.", "[0033] Additionally or alternatively in this or other embodiments, the first coefficient of friction is greater than or equal to 0.1.", "BRIEF DESCRIPTION OF THE DRAWINGS [0034] FIG. 1A is a schematic of an exemplary elevator system having a 1:1 roping arrangement;", "[0035] FIG. 1B is a schematic of another exemplary elevator system having a different roping arrangement;", "[0036] FIG. 1C is a schematic of another exemplary elevator system having a cantilevered arrangement;", "[0037] FIG. 2 is a cross-sectional view of an elevator belt;", "[0038] FIG. 3 is a cross-sectional view of a cord or rope;", "[0039] FIG. 4 is a view of an embodiment of a deflector sheave for an elevator system;", "[0040] FIG. 5 is a view of another embodiment of a deflector sheave for an elevator system;", "and [0041] FIG. 6 is a view of yet another embodiment of a deflector sheave for an elevator system.", "[0042] The detailed description explains the invention, together with advantages and features, by way of examples with reference to the drawings.", "DETAILED DESCRIPTION [0043] Shown in FIGS. 1A, 1B and 1C are schematics of exemplary traction elevator systems 10 .", "Features of the elevator system 10 that are not required for an understanding of the present invention (such as the guide rails, safeties, etc.) are not discussed herein.", "The elevator system 10 includes an elevator car 12 operatively suspended or supported in a hoistway 14 with one or more belts 16 .", "The one or more belts 16 interact with one or more deflector sheaves 18 to be routed around various components of the elevator system 10 .", "The one or more belts 16 could also be connected to a counterweight 22 , which is used to help balance the elevator system 10 and reduce the difference in belt tension on both sides of the traction sheave during operation.", "It is to be appreciated that while the embodiments herein are described as applied to coated steel belts, it is to be appreciated that the disclosure herein may similarly be applied to steel ropes, either coated or uncoated.", "[0044] The deflector sheaves 18 each have a diameter 20 , which may be the same or different than the diameters of the other deflector sheaves 18 in the elevator system 10 .", "At least one of the sheaves could be a traction sheave 24 .", "The traction sheave 24 is driven by a machine 26 .", "Movement of the traction sheave 24 by the machine 26 drives, moves and/or propels (through traction) the one or more belts 16 that are routed around the traction sheave 24 .", "[0045] In some embodiments, the elevator system 10 could use two or more belts 16 for suspending and/or driving the elevator car 12 .", "In addition, the elevator system 10 could have various configurations such that either both sides of the one or more belts 16 engage the one or more deflector sheaves 18 (such as shown in the exemplary elevator systems in FIGS. 1A, 1B or 1C ) or only one side of the one or more belts 16 engages the one or more sheaves 18 .", "[0046] FIG. 1A provides a 1:1 roping arrangement in which the one or more belts 16 terminate at the car 12 and counterweight 22 .", "FIGS. 1B and 1C provide different roping arrangements.", "Specifically, FIGS. 1B and 1C show that the car 12 and/or the counterweight 22 can have one or more deflector sheaves 18 thereon engaging the one or more belts 16 and the one or more belts 16 can terminate elsewhere, typically at a structure within the hoistway 14 (such as for a machineroomless elevator system) or within the machine room (for elevator systems utilizing a machine room).", "The number of deflector sheaves 18 used in the arrangement determines the specific roping ratio (e.g., the 2:1 roping ratio shown in FIGS. 1B and 1C or a different ratio).", "FIG. 1C also provides a cantilevered type elevator.", "The present invention could be used on elevator systems other than the exemplary types shown in FIGS. 1A, 1B and 1C .", "[0047] FIG. 2 provides a schematic of a belt construction or design.", "Each belt 16 is constructed of a plurality of wires 28 (e.g. twisted into one or more strands 30 and/or cords 32 as shown in FIG. 3 ) in a jacket 34 .", "As seen in FIG. 2 , the belt 16 has an aspect ratio greater than one (i.e. belt width is greater than belt thickness).", "The belts 16 are constructed to have sufficient flexibility when passing over the one or more deflector sheaves 18 to provide low bending stresses, meet belt life requirements and have smooth operation, while being sufficiently strong to be capable of meeting strength requirements for suspending and/or driving the elevator car 12 .", "The jacket 34 could be any suitable material, including a single material, multiple materials, two or more layers using the same or dissimilar materials, and/or a film.", "In one arrangement, the jacket 34 could be a polymer, such as an elastomer, applied to the cords 32 using, for example, an extrusion or a mold wheel process.", "In another arrangement, the jacket 34 could be a woven fabric that engages and/or integrates the cords 32 .", "As an additional arrangement, the jacket 34 could be one or more of the previously mentioned alternatives in combination.", "[0048] The jacket 34 can substantially retain the cords 32 therein.", "The phrase substantially retain means that the jacket 34 has sufficient engagement with the cords 32 to transfer torque from the machine 26 through the jacket 34 to the cords 32 to drive movement of the elevator car 12 .", "The jacket 34 could completely envelop the cords 32 (such as shown in FIG. 2 ), substantially envelop the cords 24 , or at least partially envelop the cords 32 .", "[0049] An exemplary deflector sheave 18 is shown in FIG. 4 .", "A sheave outer surface 38 includes a crown, in some embodiments a spherical crown, such that a sheave radius 40 from a sheave axis 42 to the sheave outer surface 38 is greater at a sheave center 44 of the deflector sheave 18 than at either sheave end 46 of the deflector sheave 18 .", "The crown configuration aids the belt 16 in being substantially centered on the sheave outer surface 38 between sheave ends 46 .", "As stated above, however, the crown of the deflector sheave 18 , in some embodiments a crown radius between 250 mm and 1000 mm, and the desire for low coefficient of friction of the deflector sheave 18 makes it difficult for the belt 16 to climb the crown of the deflector sheave 18 and remain centered.", "[0050] The deflector sheave 18 is uniquely configured to address the problems noted with prior art deflector sheaves.", "The deflector sheave 18 includes a high friction zone 48 and one or more low friction zones 50 , with the high friction zone 48 characterized as having a higher coefficient of friction than the low friction zones 50 .", "The high friction zone 48 is located, for example, around the sheave center 44 of the deflector sheave 18 , and in some embodiments includes about a center 25% to 50% of the sheave outer surface 38 .", "The high friction zone 48 is treated by abrasive blasting or other surface treatment or coating to provide a high friction surface to effectively guide the deflector sheave 18 up the crown of the deflector sheave 18 .", "The low friction zones 50 are located, for example, outboard of the high friction zone 48 and extend to the sheave ends 46 , and in some embodiments include about the outer 25% to 40% of the sheave outer surface 38 .", "The low friction zones 50 are characterized by having a lower coefficient of friction than the high friction sheave 48 .", "The lower coefficient of friction in the low friction zones 50 is achieved by, in some embodiments, applying a reduced-friction coating to the low friction zones 50 , for example, a Teflon nickel coating, an electroless nickel coating, a thin dense chrome coating, or a low friction plasma coating.", "In other embodiments, the lower coefficient of friction in the low friction zones 50 is achieved by masking the low friction zones 50 during the abrasive blast operation on the high friction zone 48 .", "It is to be appreciated that lower coefficient of friction in the low friction zones 50 may further be achieved via other means, for example, by the use of different materials to form the low friction zones 50 , relative to the high friction zone 48 .", "In some embodiments, the high friction zones 48 are defined as having a coefficient of friction greater than or equal to 0.1, while low friction zones 50 are defined as those having a coefficient of friction of less than 0.1.", "[0051] Referring now to FIG. 5 , in some embodiments, the deflector sheave 18 includes two or more high friction zones 48 arranged as bands in the deflector sheave 18 outer surface 38 .", "Further, in other embodiments, as shown in FIG. 6 , grooves 52 are formed in the outer surface 38 by, for example, machining.", "In some embodiments, the grooves 52 are as wide as a cord 32 of the belt 16 , are may be as small in width as 0.1 mm.", "A depth of the grooves 52 is determined by a depth required to introduce friction at edges of the grooves 52 between the edges of the grooves 52 and the belt 16 .", "In some embodiments, the groove depth, measured as a radial difference between a groove peak and a groove valley is between 0.1 mm and 1.0 mm.", "In other embodiments, the depth is between 0.25 mm and 0.5 mm.", "The groove peak may be positioned either radially above, below or at the outer surface 38 .", "In embodiments where the peak of the groove 52 is above or below the outer surface 38 , a radial distance between the peak and the outer surface is about 0.1 mm maximum to maintain tension balance of the belt 16 .", "[0052] While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments.", "Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention.", "Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments.", "Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims." ]
This application is a divisional of U.S. patent application Ser. No. 09/476,964, entitled “Flexible Flat Tension Member Termination Device” filed Jan. 11, 2000. TECHNICAL FIELD The present invention relates to elevator systems. More particularly the invention relates to a termination for a flexible flat tension member. BACKGROUND OF THE INVENTION A conventional traction elevator system includes a car, a counterweight, two or more ropes (tension members) interconnecting the car and counterweights; terminations for each end of the ropes at the connection points with the car and counterweights, a traction sheave to move the ropes and a machine to rotate the traction sheave. The ropes have traditionally been formed of laid or twisted steel wire which are easily and reliably terminated by means such as compression terminations and potted terminations. Compression type terminations for steel ropes of larger diameters (conventional steel elevator ropes) are extremely effective and reliable. The range of pressures placed on such terminations is reasonably broad without adverse consequence. Providing that the pressure applied is somewhere reasonably above the threshold pressure for retaining the ropes, the termination is effective. With an industry trend toward flat ropes, those ropes having small cross-section cords and polymeric jackets, significantly more criticality is involved in effectively terminating the same. More specifically, the polymeric coating can creep to even 50% of its original thickness when subjected to pressure. Prior art knowledge which teaches one to exceed a threshold omits a critical parameter for a flexible flat tension member. Upper limits on compression are also important for such tension members. Since current knowledge in the art of tension member terminations is less than sublime for flexible flat tension members due both to the small cord diameter and the jacket properties discussed above, the art is in need of a tension member terminating device which specifically optimizes terminations of the flexible flat tension members currently emerging in the field. SUMMARY OF THE INVENTION A flexible flat rope (tension member) termination device is disclosed herein which comprises a socket, the socket including a pair of pins, a load side bearing wall having a friction surface, and a cut side bearing wall having a friction surface. The socket defines an interior hollow sized to accept two wedges in an opposed position relative to one another which together provide compressive and frictional forces that are desirable for securing a flat rope therein, the flat rope is threaded from a load end of the termination device around a first wedge, then back downwardly around a second wedge and then upwardly to its end. The arrangement provides about 35 MPa of compressive force on the flat rope over an effective friction surface of about 75 square centimeters. No fasteners are necessary during site assembly thus speeding assembly time and reducing cost considerations while optimizing termination reliability. In order to increase the coefficient of friction of the device, the surfaces upon which the flat rope will make contact are preferably textured. By increasing friction through textured surfaces the compressive force necessary to secure the flat rope is lower. This is desirable to reduce creep and thus extend the useful service life of the flat rope. In addition to the foregoing, the reduction in creep allows for monitoring of the condition of the flat rope using magnetic flux leakage or electrical conductivity. Since creep is effectively eliminated, grounding of the rope does not occur. Thus magnetic or electrical conductivity may be monitored from one end of the rope to the other end of the rope. Since losses due to grounding are eliminated in the above discussed termination, conductive readings of the strands of the rope will accurately reflect the condition of the strands. In another embodiment of the invention, a pair of capstans are employed to provide the necessary frictionally compressional forces required to terminate a flexible flat rope. One capstan is fixed while a second capstan is moveable toward or away from the first capstan. The device may be used to terminate a tension member whose working end extends downwardly from the device or whose working end extends upwardly from the device. BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings wherein like elements are numbered alike in the several Figures FIG. 1 is a perspective view of an elevator system; FIG. 2 is a perspective assembly view of the termination device of the invention; FIG. 3 is a perspective exploded view of the of the termination device of the invention; FIG. 4 is a cross-sectional view of the termination device of the invention taken along section line 4 — 4 in FIG. 2; and FIG. 5 is a side elevation view of a second embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, the relative location of the tension member termination device of the invention can be ascertained. For clarity, an elevator system 12 is illustrated having a car 14 , a counterweight 16 , a traction drive 18 and a machine 20 . The traction drive 18 includes a tension member 22 interconnecting car 14 and counterweight 16 which member is driven by a sleeve 24 . Both ends of tension member 22 , i.e., a car end 26 and a counterweight end 28 must be terminated. It is either of these termination points for a flexible flat tension member with which the invention is concerned. An exemplary tension member of the type contemplated in this application is discussed in further detail in U.S. Ser. No. 09/031,108 filed Feb. 26, 1998 entitled Tension Member For An Elevator and U.S. Ser. No. 09/218,990 entitled Tension Member For An Elevator filed Dec. 22, 1998, both of which are entirely incorporated herein by reference. The elevator system depicted, is provided for exemplary purposes to illustrate the location of the device of the invention. Referring now to FIG. 2 a termination device 30 of the invention is illustrated. For point of reference, one of skill in the art will recognize tension member 22 which is visible at the bottom of the drawing figure and at the top of the drawing figure. The member is numbered at both places where it is visible for clarity. Tension member 22 is threaded through termination device 30 as will be discussed hereunder. Termination device 30 comprises a socket 32 of a generally tubular shape which provides sides 34 and 36 , a cut side plate 38 , and a load side plate 42 . Cut side plate 38 and load side plate 42 provide friction surfaces ( 40 at cut side plate 38 and not shown at load side plate 42 ). In a preferred construction of socket 32 of the invention, side 36 , cut side plate 38 and load side plate 42 are manufactured as a unit to which side 34 is connectable by a pair of clevis pins 50 and 54 . Preferably pins 50 and 54 each employ a cotter pin (not shown) to complete the assembly. One of ordinary skill in the art will recognize cotter pin holes 60 in pins 50 and 54 . Socket 32 is thus held together between the heads of clevis pins 50 and 54 and the respective cotter pins. Device 30 is supported by a support 44 having at an uphole end thereof a connector such as a pin hole 46 as shown. At a lower end of support 44 is a connector 48 which preferably is a sleeve as shown through which pin 50 is passable, said pin 50 being anchorable to socket 32 as illustrated. Any means of anchoring pin 50 to housing 32 is employable. It should be noted that the positioning of the pin 50 is selected to center the pin and thus the support 44 over the load side 52 of tension member 22 as is visible in FIG. 4 . By centering pin 50 with load side 52 of tension member 22 , device 30 is caused to hang straight and additional forces are not placed upon tension member 22 . The second pin 54 is provided to positionally secure a wedge through hole 55 and prevent one of the preferably two wedges employed herein from becoming unintentionally disassociated with socket 32 . Hole 55 is preferably larger in diameter than pin 54 in order to allow wedge 56 b to have play when pinned. The play is beneficial in that it facilitates self-centering of the wedge 56 b with the balance of termination device 30 . Self centering ensures a very effective termination while reducing the cost of manufacturing since tolerances of manufacture are not required to be as tight due to this self-centering feature. Referring to FIG. 4, a wedge system of the invention employs preferably two wedges that are identical to one another (ease of manufacturing). Each wedge 56 is tear drop shaped in cross section and provides a contact surface for the tension member 22 . Each angular surface of each wedge is preferably at about 15° from a centerline of each respective wedge. The curved portion of each wedge is preferably of a radius of 15 millimeters. The positioning of the two wedges in one preferred embodiment is well illustrated in FIG. 4 . It will be appreciated that the load side plate 42 and cut side plate 38 are parallel to one another and that the function of the wedges is to urge tension member 22 against friction surfaces on plates 38 and 42 . In order to terminate tension member 22 , one need merely thread the member 22 through the device 30 from the bottom (in the drawing) and around the wedges 56 as shown. Preferably at least about 200 millimeters of tension member 22 should extend out of the device 30 and beyond cut side plate 38 . Once the wedges are “set” the termination is complete and will reliably and safely hold the elevator car. It will be recognized by one of ordinary skill in the art that a single wedge 56 a would be sufficient to reliably hold the elevator car as such single wedge systems currently are in existence. Single wedge systems typically employ friction surfaces for contact with a tension member which have a coefficient of friction of about 0.25. This coefficient of friction is easy to obtain by providing a textured surface and when provided in connection with the above-identified device allows for the termination to actually use only one of the two wedges. On occasion differing coefficients may be desired or may be imposed upon the system. In such low coefficient of friction situations a conventional single wedge termination might not be as desirable or desired. The invention, because of its greater surface area and opposed wedges 56 a and 56 b allows for the use of lower coefficient of friction surfaces, while still providing a reliable termination. Under normal circumstances all of the force of tension member 22 is reacted out by the time tension member 22 has wrapped completely around wedge 56 a . In other words, there is no tension left in tension member 22 after the contact areas of wedge 56 a . For this reason, wedge 56 b plays a role only as a stop for wedge 56 a . Alternatively, the invention provides a safety backup to ensure the tension member does not slip in conditions where the coefficient of friction has degraded to less than 0.25. This can occur if the friction surfaces of plates 38 and 42 become lubricated by any number of possible lubricants. In such event, tension still remaining in the tension member beyond the contact areas of wedge 56 a because of the reduced friction is reacted out in wedge 56 b and the socket remains serviceable. In addition to ensuring a reliable termination, the invention also ensures that creep of the polymeric jacket material is not experienced. This is beneficial since it prevents grounding of the steel cords inside the polymeric jacket against the termination device 30 . Therefore it is possible to monitor continuity, either electrically or magnetically, along the individual cords. If continuity is lost or degraded, cord damage would be suspected and repaired or the tension member replaced. Referring now to FIG. 5, a second embodiment of the invention is illustrated wherein a tension member is terminated by a device having the capability of being utilized as a termination device for a tension member having a working end extending upwardly or a termination device for a tension member having a working end extending downwardly. The device includes a frame 70 which is attachable either to the top of the hoistway (not shown) or to an elevator car (not shown) or counterweight (not shown). Fixedly attached to frame 70 is bracket 72 which preferably comprises two plate like members each attached to the frame only or attached to one another via, for example, forging, etc. At one end of bracket 72 , a capstan 74 is fixedly attached thereto at a predetermined angle by any suitable mechanical affixation means. The desired angle will preferably include a positioning of one flat surface 76 of capstan 74 in a vertical position. A second capstan 78 is positioned adjacent first capstan 74 as illustrated but is not affixed to bracket 72 . Rather second capstan 78 is allowed to slide within bracket 72 in groove 80 via a pin 82 extending from capstan 78 . Groove 80 and the sliding of capstan 72 allows for simple insertion of a tension member 22 to terminate the same. The sliding provision of second capstan 78 also allows the weight of whatever object is suspended by tension member 22 to cause capstan 78 to move toward capstan 74 . This is important with respect to the termination capability of the device of the invention since the tension member 22 being wrapped as shown in FIG. 5 is compressed in the area illustrated by arrow 84 between the two capstans. It should be noted that the second capstan 78 will tend to find its own position within bracket 72 since it includes a complementary angle to that of capstan 74 . Thus, it can be expected that surface 86 of capstan 78 will orient itself in a vertical position parallel to surface 76 of capstan 74 . Tension member 22 is preferably wrapped over the curved section 88 of capstan 78 through the central area 84 between capstan 74 and capstan 78 , around the curved section 90 of capstan 74 and up to an end termination on the flat surface 76 of capstan 74 . The tension member 22 is preferably bolted to capstan 74 by a plurality of threaded fasteners (bolts) 92 , which preferably is six bolts. A plate 94 is used as a bolt seat and to compress tension member 22 against surface 76 of capstan 74 . In a preferred embodiment, the plate 94 includes curved ends 96 to prevent injury to tension member 22 . In one preferred embodiment it is noted that a backup retaining device comprises a wedge 98 adhesively mounted to a terminal end 100 of tension member 22 . Thus, in the extraordinarily unlikely event that the tension member began to slip through the termination device of this embodiment, the wedge 98 would be drawn into the confined space between bolt plate 94 and flat surface 76 of capstan 74 where it would wedge against tension member 22 and prevent further migration of the tension member 22 out of the termination device of this embodiment. Although the invention has been shown and described with respect to exemplary embodiments thereof; it should be understood by those skilled in the art that various changes, omissions, and additions may be made thereto, without departing from the spirit and scope of the invention.
A termination device for terminating a flexible flat tension member includes a socket and two opposing wedges mounted therein. One of the wedges is preferably pinned within the socket while the other wedge is removable. The invention provides a reliable termination with a safety back-up to retain the tension member even if friction in the device is reduced due to soiling with a friction reducing material.
Provide a concise summary of the essential information conveyed in the context.
[ "This application is a divisional of U.S. patent application Ser.", "No. 09/476,964, entitled “Flexible Flat Tension Member Termination Device”", "filed Jan. 11, 2000.", "TECHNICAL FIELD The present invention relates to elevator systems.", "More particularly the invention relates to a termination for a flexible flat tension member.", "BACKGROUND OF THE INVENTION A conventional traction elevator system includes a car, a counterweight, two or more ropes (tension members) interconnecting the car and counterweights;", "terminations for each end of the ropes at the connection points with the car and counterweights, a traction sheave to move the ropes and a machine to rotate the traction sheave.", "The ropes have traditionally been formed of laid or twisted steel wire which are easily and reliably terminated by means such as compression terminations and potted terminations.", "Compression type terminations for steel ropes of larger diameters (conventional steel elevator ropes) are extremely effective and reliable.", "The range of pressures placed on such terminations is reasonably broad without adverse consequence.", "Providing that the pressure applied is somewhere reasonably above the threshold pressure for retaining the ropes, the termination is effective.", "With an industry trend toward flat ropes, those ropes having small cross-section cords and polymeric jackets, significantly more criticality is involved in effectively terminating the same.", "More specifically, the polymeric coating can creep to even 50% of its original thickness when subjected to pressure.", "Prior art knowledge which teaches one to exceed a threshold omits a critical parameter for a flexible flat tension member.", "Upper limits on compression are also important for such tension members.", "Since current knowledge in the art of tension member terminations is less than sublime for flexible flat tension members due both to the small cord diameter and the jacket properties discussed above, the art is in need of a tension member terminating device which specifically optimizes terminations of the flexible flat tension members currently emerging in the field.", "SUMMARY OF THE INVENTION A flexible flat rope (tension member) termination device is disclosed herein which comprises a socket, the socket including a pair of pins, a load side bearing wall having a friction surface, and a cut side bearing wall having a friction surface.", "The socket defines an interior hollow sized to accept two wedges in an opposed position relative to one another which together provide compressive and frictional forces that are desirable for securing a flat rope therein, the flat rope is threaded from a load end of the termination device around a first wedge, then back downwardly around a second wedge and then upwardly to its end.", "The arrangement provides about 35 MPa of compressive force on the flat rope over an effective friction surface of about 75 square centimeters.", "No fasteners are necessary during site assembly thus speeding assembly time and reducing cost considerations while optimizing termination reliability.", "In order to increase the coefficient of friction of the device, the surfaces upon which the flat rope will make contact are preferably textured.", "By increasing friction through textured surfaces the compressive force necessary to secure the flat rope is lower.", "This is desirable to reduce creep and thus extend the useful service life of the flat rope.", "In addition to the foregoing, the reduction in creep allows for monitoring of the condition of the flat rope using magnetic flux leakage or electrical conductivity.", "Since creep is effectively eliminated, grounding of the rope does not occur.", "Thus magnetic or electrical conductivity may be monitored from one end of the rope to the other end of the rope.", "Since losses due to grounding are eliminated in the above discussed termination, conductive readings of the strands of the rope will accurately reflect the condition of the strands.", "In another embodiment of the invention, a pair of capstans are employed to provide the necessary frictionally compressional forces required to terminate a flexible flat rope.", "One capstan is fixed while a second capstan is moveable toward or away from the first capstan.", "The device may be used to terminate a tension member whose working end extends downwardly from the device or whose working end extends upwardly from the device.", "BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings wherein like elements are numbered alike in the several Figures FIG. 1 is a perspective view of an elevator system;", "FIG. 2 is a perspective assembly view of the termination device of the invention;", "FIG. 3 is a perspective exploded view of the of the termination device of the invention;", "FIG. 4 is a cross-sectional view of the termination device of the invention taken along section line 4 — 4 in FIG. 2;", "and FIG. 5 is a side elevation view of a second embodiment of the invention.", "DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, the relative location of the tension member termination device of the invention can be ascertained.", "For clarity, an elevator system 12 is illustrated having a car 14 , a counterweight 16 , a traction drive 18 and a machine 20 .", "The traction drive 18 includes a tension member 22 interconnecting car 14 and counterweight 16 which member is driven by a sleeve 24 .", "Both ends of tension member 22 , i.e., a car end 26 and a counterweight end 28 must be terminated.", "It is either of these termination points for a flexible flat tension member with which the invention is concerned.", "An exemplary tension member of the type contemplated in this application is discussed in further detail in U.S. Ser.", "No. 09/031,108 filed Feb. 26, 1998 entitled Tension Member For An Elevator and U.S. Ser.", "No. 09/218,990 entitled Tension Member For An Elevator filed Dec. 22, 1998, both of which are entirely incorporated herein by reference.", "The elevator system depicted, is provided for exemplary purposes to illustrate the location of the device of the invention.", "Referring now to FIG. 2 a termination device 30 of the invention is illustrated.", "For point of reference, one of skill in the art will recognize tension member 22 which is visible at the bottom of the drawing figure and at the top of the drawing figure.", "The member is numbered at both places where it is visible for clarity.", "Tension member 22 is threaded through termination device 30 as will be discussed hereunder.", "Termination device 30 comprises a socket 32 of a generally tubular shape which provides sides 34 and 36 , a cut side plate 38 , and a load side plate 42 .", "Cut side plate 38 and load side plate 42 provide friction surfaces ( 40 at cut side plate 38 and not shown at load side plate 42 ).", "In a preferred construction of socket 32 of the invention, side 36 , cut side plate 38 and load side plate 42 are manufactured as a unit to which side 34 is connectable by a pair of clevis pins 50 and 54 .", "Preferably pins 50 and 54 each employ a cotter pin (not shown) to complete the assembly.", "One of ordinary skill in the art will recognize cotter pin holes 60 in pins 50 and 54 .", "Socket 32 is thus held together between the heads of clevis pins 50 and 54 and the respective cotter pins.", "Device 30 is supported by a support 44 having at an uphole end thereof a connector such as a pin hole 46 as shown.", "At a lower end of support 44 is a connector 48 which preferably is a sleeve as shown through which pin 50 is passable, said pin 50 being anchorable to socket 32 as illustrated.", "Any means of anchoring pin 50 to housing 32 is employable.", "It should be noted that the positioning of the pin 50 is selected to center the pin and thus the support 44 over the load side 52 of tension member 22 as is visible in FIG. 4 .", "By centering pin 50 with load side 52 of tension member 22 , device 30 is caused to hang straight and additional forces are not placed upon tension member 22 .", "The second pin 54 is provided to positionally secure a wedge through hole 55 and prevent one of the preferably two wedges employed herein from becoming unintentionally disassociated with socket 32 .", "Hole 55 is preferably larger in diameter than pin 54 in order to allow wedge 56 b to have play when pinned.", "The play is beneficial in that it facilitates self-centering of the wedge 56 b with the balance of termination device 30 .", "Self centering ensures a very effective termination while reducing the cost of manufacturing since tolerances of manufacture are not required to be as tight due to this self-centering feature.", "Referring to FIG. 4, a wedge system of the invention employs preferably two wedges that are identical to one another (ease of manufacturing).", "Each wedge 56 is tear drop shaped in cross section and provides a contact surface for the tension member 22 .", "Each angular surface of each wedge is preferably at about 15° from a centerline of each respective wedge.", "The curved portion of each wedge is preferably of a radius of 15 millimeters.", "The positioning of the two wedges in one preferred embodiment is well illustrated in FIG. 4 .", "It will be appreciated that the load side plate 42 and cut side plate 38 are parallel to one another and that the function of the wedges is to urge tension member 22 against friction surfaces on plates 38 and 42 .", "In order to terminate tension member 22 , one need merely thread the member 22 through the device 30 from the bottom (in the drawing) and around the wedges 56 as shown.", "Preferably at least about 200 millimeters of tension member 22 should extend out of the device 30 and beyond cut side plate 38 .", "Once the wedges are “set”", "the termination is complete and will reliably and safely hold the elevator car.", "It will be recognized by one of ordinary skill in the art that a single wedge 56 a would be sufficient to reliably hold the elevator car as such single wedge systems currently are in existence.", "Single wedge systems typically employ friction surfaces for contact with a tension member which have a coefficient of friction of about 0.25.", "This coefficient of friction is easy to obtain by providing a textured surface and when provided in connection with the above-identified device allows for the termination to actually use only one of the two wedges.", "On occasion differing coefficients may be desired or may be imposed upon the system.", "In such low coefficient of friction situations a conventional single wedge termination might not be as desirable or desired.", "The invention, because of its greater surface area and opposed wedges 56 a and 56 b allows for the use of lower coefficient of friction surfaces, while still providing a reliable termination.", "Under normal circumstances all of the force of tension member 22 is reacted out by the time tension member 22 has wrapped completely around wedge 56 a .", "In other words, there is no tension left in tension member 22 after the contact areas of wedge 56 a .", "For this reason, wedge 56 b plays a role only as a stop for wedge 56 a .", "Alternatively, the invention provides a safety backup to ensure the tension member does not slip in conditions where the coefficient of friction has degraded to less than 0.25.", "This can occur if the friction surfaces of plates 38 and 42 become lubricated by any number of possible lubricants.", "In such event, tension still remaining in the tension member beyond the contact areas of wedge 56 a because of the reduced friction is reacted out in wedge 56 b and the socket remains serviceable.", "In addition to ensuring a reliable termination, the invention also ensures that creep of the polymeric jacket material is not experienced.", "This is beneficial since it prevents grounding of the steel cords inside the polymeric jacket against the termination device 30 .", "Therefore it is possible to monitor continuity, either electrically or magnetically, along the individual cords.", "If continuity is lost or degraded, cord damage would be suspected and repaired or the tension member replaced.", "Referring now to FIG. 5, a second embodiment of the invention is illustrated wherein a tension member is terminated by a device having the capability of being utilized as a termination device for a tension member having a working end extending upwardly or a termination device for a tension member having a working end extending downwardly.", "The device includes a frame 70 which is attachable either to the top of the hoistway (not shown) or to an elevator car (not shown) or counterweight (not shown).", "Fixedly attached to frame 70 is bracket 72 which preferably comprises two plate like members each attached to the frame only or attached to one another via, for example, forging, etc.", "At one end of bracket 72 , a capstan 74 is fixedly attached thereto at a predetermined angle by any suitable mechanical affixation means.", "The desired angle will preferably include a positioning of one flat surface 76 of capstan 74 in a vertical position.", "A second capstan 78 is positioned adjacent first capstan 74 as illustrated but is not affixed to bracket 72 .", "Rather second capstan 78 is allowed to slide within bracket 72 in groove 80 via a pin 82 extending from capstan 78 .", "Groove 80 and the sliding of capstan 72 allows for simple insertion of a tension member 22 to terminate the same.", "The sliding provision of second capstan 78 also allows the weight of whatever object is suspended by tension member 22 to cause capstan 78 to move toward capstan 74 .", "This is important with respect to the termination capability of the device of the invention since the tension member 22 being wrapped as shown in FIG. 5 is compressed in the area illustrated by arrow 84 between the two capstans.", "It should be noted that the second capstan 78 will tend to find its own position within bracket 72 since it includes a complementary angle to that of capstan 74 .", "Thus, it can be expected that surface 86 of capstan 78 will orient itself in a vertical position parallel to surface 76 of capstan 74 .", "Tension member 22 is preferably wrapped over the curved section 88 of capstan 78 through the central area 84 between capstan 74 and capstan 78 , around the curved section 90 of capstan 74 and up to an end termination on the flat surface 76 of capstan 74 .", "The tension member 22 is preferably bolted to capstan 74 by a plurality of threaded fasteners (bolts) 92 , which preferably is six bolts.", "A plate 94 is used as a bolt seat and to compress tension member 22 against surface 76 of capstan 74 .", "In a preferred embodiment, the plate 94 includes curved ends 96 to prevent injury to tension member 22 .", "In one preferred embodiment it is noted that a backup retaining device comprises a wedge 98 adhesively mounted to a terminal end 100 of tension member 22 .", "Thus, in the extraordinarily unlikely event that the tension member began to slip through the termination device of this embodiment, the wedge 98 would be drawn into the confined space between bolt plate 94 and flat surface 76 of capstan 74 where it would wedge against tension member 22 and prevent further migration of the tension member 22 out of the termination device of this embodiment.", "Although the invention has been shown and described with respect to exemplary embodiments thereof;", "it should be understood by those skilled in the art that various changes, omissions, and additions may be made thereto, without departing from the spirit and scope of the invention." ]
CROSS-REFERENCE TO RELATED APPLICATIONS This application is a divisional application of U.S. application Ser. No. 13/965,717, filed on Aug. 13, 2013, which is hereby incorporated by reference for all purposes as if fully set forth herein. TECHNICAL FIELD Various exemplary embodiments disclosed herein relate generally to communications networking. BACKGROUND General radio packet service (GPRS) is a packet oriented data service on the 2G and 3G cellular communication system's global system for mobile communication (GSM). GPRS is a best effort packet based service where a user is charged for data usage. GPRS is now part of the 3rd generation partnership project (3GPP). When a GPRS service request is made an access point name aggregate maximum bit rate (APN-AMBR) may specify the AMBR that the service requests. The APN-AMBR services as a limit on the amount of bandwidth that may be consumed by the session. SUMMARY A brief summary of various exemplary embodiments is presented below. Some simplifications and omissions may be made in the following summary, which is intended to highlight and introduce some aspects of the various exemplary embodiments, but not to limit the scope of the invention. Detailed descriptions of a preferred exemplary embodiment adequate to allow those of ordinary skill in the art to make and use the inventive concepts will follow in later sections, Various embodiments described herein relate to a method performed by a policy and charging rules node (PCRN), the method including: receiving a credit control request (CCR) message from a packet data network gateway (PGW) based upon a general radio packet service (GPRS) internet protocol connectivity access network (IP-CAN) session request; determining that an operator policy rule specifies an aggregate maximum bit rate (APN-AMBR) value; determining that the CCR message includes an APN-AMBR value; setting an APN-AMBR value for the GPRS IP-CAN session to the APN-AMBR value specified by the operator policy rule; setting a GPRS IP-CAN session maximum bit rate download/upload (MBR DL/UL) value to the lowest of the APN-AMBR value specified by the operator policy rule and a subscriber MBR DL/UL value; and sending a credit control answer (CCA) message to the PGW with the selected APN-AMBR and MBR DL/UL values. Various embodiments described herein relate to a method performed by a policy and charging rules node (PCRN), the method including: receiving a credit control request (CCR) message from a packet data network gateway (PGW) based upon a general radio packet service (GPRS) internet protocol connectivity access network (IP-CAN) session request; determining that no operator policy rule specifies an aggregate maximum bit rate (APN-AMBR) value; determining that the CCR message includes an APN-AMBR value; setting an APN-AMBR value for the GPRS IP-CAN session to an APN-AMBR value for a subscriber associated with the GPRS IP-CAN session; setting a GPRS IP-CAN session maximum bit rate download/upload (MBR DL/UL) value to the lowest of the subscriber APN-AMBR value and a subscriber MBR DL/UL value; and sending a credit control answer (CCA) message to the PGW with the selected APN-AMBR and MBR DL/UL values. Various embodiments described herein relate to a method performed by a policy and charging rules node (PCRN), the method including: receiving a credit control request (CCR) message from a packet data network gateway (PGW) based upon a general radio packet service (GPRS) internet protocol connectivity access network (IP-CAN) session request; determining that no operator policy rule specifies an aggregate maximum bit rate (APN-AMBR) value; determining that the CCR message does not include an APN-AMBR value; setting a GPRS IP-CAN session maximum bit rate download/upload (MBR DL/UL) value to the lowest of a subscriber APN-AMBR value and a subscriber MBR DL/UL value; and sending a credit control answer (CCA) message to the PGW with the selected APN-MBR DL/UL values and without an APN-AMBR value. BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand various exemplary embodiments, reference is made to the accompanying drawings, wherein: FIG. 1 illustrates an exemplary subscriber network 100 for providing various data services; FIG. 2 illustrates a first example of message flow regarding APN-AMBR; FIG. 3 illustrates a second example of message flow regarding APN-AMBR; FIG. 4 illustrates a third example of message flow regarding APN-AMBR; FIG. 5 illustrates a fourth example of message flow regarding APN-AMBR; and FIG. 6 illustrates a method used by the PCRN to determine the AN-AMBR and MBR DL/UL values for a GPRS session. DETAILED DESCRIPTION The description and drawings illustrate the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Additionally, the term, “or,” as used herein, refers to a non-exclusive or (i.e., and/or), unless otherwise indicated (e.g., “or else” or “or in the alternative”). Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. As used herein, the terms “context” and “context object” will be understood to be synonymous, unless otherwise indicated. Long term evolution (LTE) systems may include the use of GPRS networks. Legacy GPRS networks may not use APN-AMBR AVP, while newer GPRS networks may use APN-AMBR to regulate non-GBR bearers of a GPRS session. Furthermore, it is desirable to be able to specify GPRS session APN-AMBR according to different subscriber profiles, and the changes to the subscriber profile should be reflected dynamically in APN-AMBR of the corresponding session. When a mobile user moves from different GPRS access networks, e.g. from an network where APN-AMBR is not used to a network where APN-AMBR is used or from a network where APN-AMBR is used to a network where APN-AMBR is not used, this change needs to be reflected in PCRF decision. There is a need to develop comprehensive strategy in the implementation of an LTE system in order to address above mentioned challenges. Embodiments of systems and methods to address these issues with APN-AMBR are described below. In these embodiments, a subscriber APN-AMBR or an APN-AMBR authorized by a policy and charging rules node (PCRN) may be used in setting for the GPRS session as described in greater detail below. FIG. 1 illustrates an exemplary subscriber network 100 for providing various data services. Exemplary subscriber network 100 may be a telecommunications network or other network for providing access to various services. Exemplary subscriber network 100 may include user equipment 110 , base station 120 , evolved packet core (EPC) 130 , packet data network 140 , and application node (AN) 150 . User equipment 110 may be a device that communicates with packet data network 140 for providing the end-user with a data service. Such data service may include, for example, voice communication, text messaging, multimedia streaming, and Internet access. More specifically, in various exemplary embodiments, user equipment 110 is a personal or laptop computer, wireless email device, cell phone, smart phone, television set-top box, or any other device capable of communicating with other devices via EPC 130 . Base station 120 may be a device that enables communication between user equipment 110 and EPC 130 . For example, base station 120 may be a base transceiver station such as an evolved nodeB (eNodeB) as defined by 3GPP standards. Thus, base station 120 may be a device that communicates with user equipment 110 via a first medium, such as radio waves, and communicates with EPC 130 via a second medium, such as Ethernet cable. Base station 120 may be in direct communication with EPC 130 or may communicate via a number of intermediate nodes (not shown). In various embodiments, multiple base stations (not shown) may be present to provide mobility to user equipment 110 . Note that in various alternative embodiments, user equipment 110 may communicate directly with evolved packet core 130 . In such embodiments, base station 120 may not be present. Evolved packet core (EPC) 130 may be a device or network of devices that provides user equipment 110 with gateway access to packet data network 140 . EPC 130 may further charge a subscriber for use of provided data services and ensure that particular quality of experience (QoE) standards are met. Thus, EPC 130 may be implemented, at least in part, according to the 3GPP TS 29.212, 29.213, and 29.214 standards. Accordingly, EPC 130 may include a serving gateway (SGW) 132 , a packet data network gateway (PGW) 134 , a policy and charging rules node (PCRN) 136 and a subscriber profile repository (SPR) 138 . Serving gateway (SGW) 132 may be a device that manages data paths between the base station 120 and PGW 134 . The data paths may include virtual containers called bearers with unique Quality of Service (QoS) characteristics. The bearers may include virtual connections called service data flows (SDFs). In various embodiments where user equipment 110 is a mobile device and base station 120 is an eNodeB, SGW 132 may be responsible for establishing new bearers when the mobile device changes eNodeB. The SGW 132 may implement a bearer binding and event reporting function (BBERF) according to the 3GPP TS 29.212, 29.213, and 29.214 standards. In various embodiments, EPC 130 may include multiple serving gateways. Packet data network gateway (PGW) 134 may be a device that provides gateway access to packet data network 140 . PGW 134 may be the final device within the EPC 130 that receives packets sent by user equipment 110 toward packet data network 140 via SGW 132 . PGW 134 may include a policy and charging enforcement function (PCEF) that enforces policy and charging control (PCC) rules for each service data flow (SDF). Thus, PGW 134 may be a policy and charging enforcement node (PCEN). The PGW may act as a gateway GPRS support node (GGSN) when the subscriber network 100 implements a GPRS network. PGW 134 may request new PCC rules from PCRN 136 by sending a CCR message via the Gx interface. PGW 134 may also include a number of additional features such as, for example, packet filtering, deep packet inspection, and subscriber charging support. Policy and charging rules node (PCRN) 136 may be a device that receives requests for application services, generates PCC rules, and provides PCC rules to the PGW 134 and/or other PCENs (not shown). PCRN 136 may be in communication with AN 150 via an Rx interface. PCRN 136 may receive a service request in the form of an AA-Request (AAR) 160 from AN 150 . PCRN 136 may also be in communication with SGW 132 and PGW 134 via a Gxx and a Gx interface, respectively. PCRN 136 may receive a service request in the form of a credit control request (CCR) 170 from SGW 132 or PGW 134 . In various embodiments, AAR 160 and CCR 170 may represent two independent service requests to be processed separately, while in other embodiments, AAR 160 and CCR 170 may carry information regarding a single service request and PCRN 136 may create at least one PCC rule based on the combination of AAR 160 and CCR 170 . In various embodiments, PCRN 136 may be capable of handling both single-message and paired-message service requests. Upon creating a new PCC rule or upon request by the PGW 134 , PCRN 136 may provide a PCC rule to PGW 134 via the Gx interface. In various embodiments, such as those implementing the PMIP standard for example, PCRN 136 may also generate QoS rules. Upon creating a new QoS rule or upon request by the SGW 132 , PCRN 136 may provide a QoS rule to SGW 132 via the Gxx interface. As will be discussed in further detail below, PCRN 136 may receive a request to update a PCC rule with new filters. PCRN 136 may receive an update CCR 170 from PGW 134 indicating one or more new filters and a reference filter. PCRN 136 may determine an existing PCC rule and related information based on the reference filter. PCRN 136 may determine new QoS-information for the PCC rule using information regarding the new filters and existing filters. PCRN 136 may also control for removed filters and flow direction. PCRN 136 may generate a new PCC rule to replace the existing PCC rule. Subscription profile repository (SPR) 138 may be a device that stores information related to subscribers to the subscriber network 100 . Thus, SPR 138 may include a machine-readable storage medium such as read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and/or similar storage media. SPR 138 may be a component of PCRN 136 or may constitute an independent node within EPC 130 . Data stored by SPR 138 may include an identifier of each subscriber and indications of subscription information for each subscriber such as bandwidth limits, charging parameters, subscriber priority, and subscriber service preferences. Packet data network 140 may be any network for providing data communications between user equipment 110 and other devices connected to packet data network 140 , such as AN 150 . Further, packet data network 140 may provide, for example, phone and/or Internet service to various user devices in communication with packet data network 140 . Application Node (AN) 150 may be a device that provides an application service to user equipment 110 . Thus, AN 150 may be a server or other device that provides, for example, streaming video service to user equipment 110 . AN 150 may further be in communication with the PCRN 136 of the EPC 130 via an Rx interface. When AN 150 is to begin providing application service to user equipment 110 , AN 150 may generate a service request message, such as an AA-Request (AAR) according to the Diameter protocol, to notify the PCRN 136 that resources should be allocated for the application service. Such an service request message may include information such as an identification of the subscriber using the application service and an identification of the particular SDFs and filters that must be established within an internet protocol connectivity access network (IP-CAN) session in order to provide the requested service. AN 150 may communicate such an service request to the PCRN via the Rx interface 215 . Four examples will be described below illustrating embodiments that set the APN-AMBR in various situations. FIG. 2 illustrates a first example of message flow regarding APN-AMBR. In this example, the PGW 134 sends a CCR without the APN-AMBR DL/UL AVPs (download/upload attribute value pairs) or QCI_9 maximum bit rate download/upload (MBR DL/UL) AVPs to the PCRN 136 . The PCRN 136 sends a SPR profile request to the SPR 138 to request the APN-AMBR and MBR DL/UL information of the subscriber. The SPR 138 sends a response to the PCRN 136 indicating that the APN-AMBR limit DL/UP=30 Mbps and that the QCI_9 MBR DL/UL=60 Mbps. The PCRN 136 determines that the primary bearer QCI_9 MBR DL/UL value should be 30 Mpbs based upon the APN-AMBR limit of 30 Mbps even though the subscriber has an authorized QCI_9 MBR DL/UL=60 Mbps. In this case the lower APN-AMBR value is the limiting value and hence becomes the limit. The PCRN 136 then sends a CCA message indicating that the QCI_9 MBR DL/UL=30 Mbps and does not specify an APN-AMBR because there was no APN-AMBR specified in the CCR received from the PGW 134 . In the above description as well as the descriptions below, the CCR and CCA messages may be initialization messages or modification messages. FIG. 3 illustrates a second example of message flow regarding APN-AMBR. In this example, the PGW 134 sends a CCR with the APN-AMBR DL/UL=50 Mbps and the QCI_9 MBR DL/UL 50 Mbps to the PCRN 136 . The PCRN 136 sends a SPR profile request to the SPR 138 to request the APN-AMBR and MBR DL/UL information of the subscriber. The SPR 138 sends a response to the PCRN 136 indicating that the APN-AMBR limit DL/UL=60 Mbps and that the QCI_9 MBR DL/UL=30 Mbps. The PCRN 136 determines that the APN-AMBR value should be 60 mbps based upon the subscribers APN-AMBR value. The PCRN 136 determines that the primary bearer QCI_9 MBR DL/UL value should be 30 Mpbs based upon the QCI_9 MBR DL/UL limit of 30 Mbps even though the subscriber has an authorized APN-AMBR=60 Mbps. In this case the lower QCI_9 MBR DL/UL value is the limiting value and hence becomes the limit. The PCRN 136 then sends a CCA message indicating that the QCI_9 MBR DL/UL=30 Mbps and that the APN-AMBR=60 Mbps. FIG. 4 illustrates a third example of message flow regarding APN-AMBR. In this example, the PGW 134 sends a CCR without the APN-AMBR DL/UL AVPs (download/upload attribute value pairs) or QCI_9 MBR DL/UL AVPs to the PCRN 136 . The PCRN 136 determines that an operator policy rule action sets the APN-AMBR=100 Mbps. The PCRN 136 sends a SPR profile request to the SPR 138 to request the APN-AMBR and MBR DL/UL information of the subscriber. The SPR 138 sends a response to the PCRN 136 indicating that the APN-AMBR limit DL/UP=30 Mbps and that the QCI_9 MBR DL/UL=60 Mbps. The PCRN 136 determines that the APN-AMBR value should be 100 Mbps based upon the operator policy rule. The PCRN 136 determines that the primary bearer QCI_9 MBR DL/UL value should be 60 Mpbs based upon the QCI_9 MBR DL/UL limit of 60 Mbps even though the subscriber has an authorized APN-AMBR=30 Mbps. In this case the APN-AMBR value has been set to 100 Mpbs so the subscriber QCI_9 MBR DL/UL value of 60 Mbps is the limiting value and hence becomes the limit. The PCRN 136 then sends a CCA message indicating that the QCI_9 MBR DL/UL=60 Mbps and that the APN-AMBR=100 Mbps. FIG. 5 illustrates a fourth example of message flow regarding APN-AMBR. This example begins the same as that in FIG. 3 . The PGW 134 sends a CCR with the APN-AMBR DL/UL=50 Mbps and the QCI_9 MBR DL/UL 50 Mbps to the PCRN 136 . The PCRN 136 sends a SPR profile request to the SPR 138 to request the APN-AMBR and MBR DL/UL information of the subscriber. The SPR 138 sends a response to the PCRN 136 indicating that the APN-AMBR limit DL/UL=60 Mbps and that the QCI_9 MBR DL/UL=30 Mbps. The PCRN 136 determines that the APN-AMBR value should be 60 mbps based upon the subscribers APN-AMBR value. The PCRN 136 determines that the primary bearer QCI_9 MBR DL/UL value should be 30 Mpbs based upon the QCI_9 MBR DL/UL limit of 30 Mbps even though the subscriber has an authorized APN-AMBR=60 Mbps. In this case the lower QCI_9 MBR DL/UL value is the limiting value and hence becomes the limit. The PCRN 136 then sends a CCA message indicating that the QCI_9 MBR DL/UL=30 Mbps and that the APN-AMBR=60 Mbps. Next, the subscriber profile APN-AMBR is changed to 1 Mbps from 60 Mbps. The SPR 138 sends a SPR update notification to the PCRN 136 . The PCRN determines that the new subscriber APN-AMBR of 1 Mbps is now the limiting factor for the session. Accordingly, the PCRN 136 then sends a RAR message indicating that the QCI_9 MBR DL/UL=1 Mbps and that the APN-AMBR=1 Mbps FIG. 6 illustrates a method used by the PCRN to determine the AN-AMBR and MBR DL/UL values for a GPRS session. The method begins at step 605 . The PCRN 136 first receives CCR for a GPRS IP-CAN session request 610 . Next, the PCRN 136 determines if an operator policy rule action for the APN-AMBR has been specified 615 . If not, the PCRN 136 next determines if the CCR includes an APN-AMBR 620 . If not, then the PCRN sets the GPRS session MBR DL/UL to the lowest of the subscriber APN-AMBR and the subscriber MBR DL/UL 625 . The PCRN 136 then sends a CCA message to the PGW 134 with the selected MBR DL/UL value and without an APN-AMBR value 630 . The method then ends at 635 . If an operator policy rule action for the APN-AMBR has been specified 615 , the PCRN sets the GPRS session APN-AMBR to the APN-AMBR value specified by the operator policy rule action 645 . Next, the PCRN 136 sets the GPRS session MBR DL/UL to the lowest of the operator specified APN-AMBR and the subscriber MBR DL/UL 650 . The PCRN 136 then sends a CCA message to the PGW 134 with the selected APN-AMBR and MBR DL/UL values 655 . The method then ends at 635 . If the PCRN 136 determines that the CCR includes an APN-AMBR 620 , the PCRN 136 sets the GPRS session APN-AMBR to the subscriber APN-AMBR value 655 . The PCRN 136 then sets the GPRS session MBR DL/UL to the lowest of the subscriber APN-AMBR and the subscriber MBR DL/UL 670 . The PCRN 136 then sends a CCA message to the PGW 134 with the selected APN-AMBR and MBR DL/UL values 655 . The method then ends at 635 . The method described in FIG. 6 may also be used when the subscriber APN-AMBR is updated. In such a case, the PCRN would receive a SPR update notification at 610 . Further, the PCRN 136 would send a RAR message to the PGW 134 instead of a CCA message to update the APN-AMBR and MBR DL/UL values at steps 630 and 655 . Otherwise, the APN-AMBR and MBR DL/UL values will be selected in the same manner. It should be apparent from the foregoing description that various exemplary embodiments of the invention may be implemented in hardware. Furthermore, various exemplary embodiments may be implemented as instructions stored on a machine-readable storage medium, which may be read and executed by at least one processor to perform the operations described in detail herein. A machine-readable storage medium may include any mechanism for storing information in a form readable by a machine, such as a personal or laptop computer, a server, or other computing device. Thus, a tangible and non-transitory machine-readable storage medium may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and similar storage media. Further, as used herein, the term “processor” will be understood to encompass a microprocessor, field programmable gate array (FPGA), application-specific integrated circuit (ASIC), or any other device capable of performing the functions described herein. It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative circuitry embodying the principles of the invention. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in machine readable media and so executed by a computer or processor, whether or not such computer or processor is explicitly shown. Although the various exemplary embodiments have been described in detail with particular reference to certain exemplary aspects thereof, it should be understood that the invention is capable of other embodiments and its details are capable of modifications in various obvious respects. As is readily apparent to those skilled in the art, variations and modifications can be effected while remaining within the spirit and scope of the invention. Accordingly, the foregoing disclosure, description, and figures are for illustrative purposes only and do not in any way limit the invention, which is defined only by the claims.
Various exemplary embodiments relate to a method performed by a policy and charging rules node (PCRN), the method including: receiving a credit control request (CCR) message from a packet data network gateway (PGW) based upon a general radio packet service (GPRS) internet protocol connectivity access network (IP-CAN) session request; determining that no operator policy rule specifies an aggregate maximum bit rate (APN-AMBR) value; determining that the CCR message includes an APN-AMBR value; setting an APN-AMBR value for the GPRS IP-CAN session to an APN-AMBR value for a subscriber associated with the GPRS IP-CAN session; setting a GPRS IP-CAN session maximum bit rate download/upload (MBR DL/UL) value to the lowest of the subscriber APN-AMBR value and a subscriber MBR DL/UL value; and sending a credit control answer (CCA) message to the PGW with the selected APN-AMBR and MBR DL/UL values.
Briefly summarize the main idea's components and working principles as described in the context.
[ "CROSS-REFERENCE TO RELATED APPLICATIONS This application is a divisional application of U.S. application Ser.", "No. 13/965,717, filed on Aug. 13, 2013, which is hereby incorporated by reference for all purposes as if fully set forth herein.", "TECHNICAL FIELD Various exemplary embodiments disclosed herein relate generally to communications networking.", "BACKGROUND General radio packet service (GPRS) is a packet oriented data service on the 2G and 3G cellular communication system's global system for mobile communication (GSM).", "GPRS is a best effort packet based service where a user is charged for data usage.", "GPRS is now part of the 3rd generation partnership project (3GPP).", "When a GPRS service request is made an access point name aggregate maximum bit rate (APN-AMBR) may specify the AMBR that the service requests.", "The APN-AMBR services as a limit on the amount of bandwidth that may be consumed by the session.", "SUMMARY A brief summary of various exemplary embodiments is presented below.", "Some simplifications and omissions may be made in the following summary, which is intended to highlight and introduce some aspects of the various exemplary embodiments, but not to limit the scope of the invention.", "Detailed descriptions of a preferred exemplary embodiment adequate to allow those of ordinary skill in the art to make and use the inventive concepts will follow in later sections, Various embodiments described herein relate to a method performed by a policy and charging rules node (PCRN), the method including: receiving a credit control request (CCR) message from a packet data network gateway (PGW) based upon a general radio packet service (GPRS) internet protocol connectivity access network (IP-CAN) session request;", "determining that an operator policy rule specifies an aggregate maximum bit rate (APN-AMBR) value;", "determining that the CCR message includes an APN-AMBR value;", "setting an APN-AMBR value for the GPRS IP-CAN session to the APN-AMBR value specified by the operator policy rule;", "setting a GPRS IP-CAN session maximum bit rate download/upload (MBR DL/UL) value to the lowest of the APN-AMBR value specified by the operator policy rule and a subscriber MBR DL/UL value;", "and sending a credit control answer (CCA) message to the PGW with the selected APN-AMBR and MBR DL/UL values.", "Various embodiments described herein relate to a method performed by a policy and charging rules node (PCRN), the method including: receiving a credit control request (CCR) message from a packet data network gateway (PGW) based upon a general radio packet service (GPRS) internet protocol connectivity access network (IP-CAN) session request;", "determining that no operator policy rule specifies an aggregate maximum bit rate (APN-AMBR) value;", "determining that the CCR message includes an APN-AMBR value;", "setting an APN-AMBR value for the GPRS IP-CAN session to an APN-AMBR value for a subscriber associated with the GPRS IP-CAN session;", "setting a GPRS IP-CAN session maximum bit rate download/upload (MBR DL/UL) value to the lowest of the subscriber APN-AMBR value and a subscriber MBR DL/UL value;", "and sending a credit control answer (CCA) message to the PGW with the selected APN-AMBR and MBR DL/UL values.", "Various embodiments described herein relate to a method performed by a policy and charging rules node (PCRN), the method including: receiving a credit control request (CCR) message from a packet data network gateway (PGW) based upon a general radio packet service (GPRS) internet protocol connectivity access network (IP-CAN) session request;", "determining that no operator policy rule specifies an aggregate maximum bit rate (APN-AMBR) value;", "determining that the CCR message does not include an APN-AMBR value;", "setting a GPRS IP-CAN session maximum bit rate download/upload (MBR DL/UL) value to the lowest of a subscriber APN-AMBR value and a subscriber MBR DL/UL value;", "and sending a credit control answer (CCA) message to the PGW with the selected APN-MBR DL/UL values and without an APN-AMBR value.", "BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand various exemplary embodiments, reference is made to the accompanying drawings, wherein: FIG. 1 illustrates an exemplary subscriber network 100 for providing various data services;", "FIG. 2 illustrates a first example of message flow regarding APN-AMBR;", "FIG. 3 illustrates a second example of message flow regarding APN-AMBR;", "FIG. 4 illustrates a third example of message flow regarding APN-AMBR;", "FIG. 5 illustrates a fourth example of message flow regarding APN-AMBR;", "and FIG. 6 illustrates a method used by the PCRN to determine the AN-AMBR and MBR DL/UL values for a GPRS session.", "DETAILED DESCRIPTION The description and drawings illustrate the principles of the invention.", "It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its scope.", "Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions.", "Additionally, the term, “or,” as used herein, refers to a non-exclusive or (i.e., and/or), unless otherwise indicated (e.g., “or else”", "or “or in the alternative”).", "Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.", "As used herein, the terms “context”", "and “context object”", "will be understood to be synonymous, unless otherwise indicated.", "Long term evolution (LTE) systems may include the use of GPRS networks.", "Legacy GPRS networks may not use APN-AMBR AVP, while newer GPRS networks may use APN-AMBR to regulate non-GBR bearers of a GPRS session.", "Furthermore, it is desirable to be able to specify GPRS session APN-AMBR according to different subscriber profiles, and the changes to the subscriber profile should be reflected dynamically in APN-AMBR of the corresponding session.", "When a mobile user moves from different GPRS access networks, e.g. from an network where APN-AMBR is not used to a network where APN-AMBR is used or from a network where APN-AMBR is used to a network where APN-AMBR is not used, this change needs to be reflected in PCRF decision.", "There is a need to develop comprehensive strategy in the implementation of an LTE system in order to address above mentioned challenges.", "Embodiments of systems and methods to address these issues with APN-AMBR are described below.", "In these embodiments, a subscriber APN-AMBR or an APN-AMBR authorized by a policy and charging rules node (PCRN) may be used in setting for the GPRS session as described in greater detail below.", "FIG. 1 illustrates an exemplary subscriber network 100 for providing various data services.", "Exemplary subscriber network 100 may be a telecommunications network or other network for providing access to various services.", "Exemplary subscriber network 100 may include user equipment 110 , base station 120 , evolved packet core (EPC) 130 , packet data network 140 , and application node (AN) 150 .", "User equipment 110 may be a device that communicates with packet data network 140 for providing the end-user with a data service.", "Such data service may include, for example, voice communication, text messaging, multimedia streaming, and Internet access.", "More specifically, in various exemplary embodiments, user equipment 110 is a personal or laptop computer, wireless email device, cell phone, smart phone, television set-top box, or any other device capable of communicating with other devices via EPC 130 .", "Base station 120 may be a device that enables communication between user equipment 110 and EPC 130 .", "For example, base station 120 may be a base transceiver station such as an evolved nodeB (eNodeB) as defined by 3GPP standards.", "Thus, base station 120 may be a device that communicates with user equipment 110 via a first medium, such as radio waves, and communicates with EPC 130 via a second medium, such as Ethernet cable.", "Base station 120 may be in direct communication with EPC 130 or may communicate via a number of intermediate nodes (not shown).", "In various embodiments, multiple base stations (not shown) may be present to provide mobility to user equipment 110 .", "Note that in various alternative embodiments, user equipment 110 may communicate directly with evolved packet core 130 .", "In such embodiments, base station 120 may not be present.", "Evolved packet core (EPC) 130 may be a device or network of devices that provides user equipment 110 with gateway access to packet data network 140 .", "EPC 130 may further charge a subscriber for use of provided data services and ensure that particular quality of experience (QoE) standards are met.", "Thus, EPC 130 may be implemented, at least in part, according to the 3GPP TS 29.212, 29.213, and 29.214 standards.", "Accordingly, EPC 130 may include a serving gateway (SGW) 132 , a packet data network gateway (PGW) 134 , a policy and charging rules node (PCRN) 136 and a subscriber profile repository (SPR) 138 .", "Serving gateway (SGW) 132 may be a device that manages data paths between the base station 120 and PGW 134 .", "The data paths may include virtual containers called bearers with unique Quality of Service (QoS) characteristics.", "The bearers may include virtual connections called service data flows (SDFs).", "In various embodiments where user equipment 110 is a mobile device and base station 120 is an eNodeB, SGW 132 may be responsible for establishing new bearers when the mobile device changes eNodeB.", "The SGW 132 may implement a bearer binding and event reporting function (BBERF) according to the 3GPP TS 29.212, 29.213, and 29.214 standards.", "In various embodiments, EPC 130 may include multiple serving gateways.", "Packet data network gateway (PGW) 134 may be a device that provides gateway access to packet data network 140 .", "PGW 134 may be the final device within the EPC 130 that receives packets sent by user equipment 110 toward packet data network 140 via SGW 132 .", "PGW 134 may include a policy and charging enforcement function (PCEF) that enforces policy and charging control (PCC) rules for each service data flow (SDF).", "Thus, PGW 134 may be a policy and charging enforcement node (PCEN).", "The PGW may act as a gateway GPRS support node (GGSN) when the subscriber network 100 implements a GPRS network.", "PGW 134 may request new PCC rules from PCRN 136 by sending a CCR message via the Gx interface.", "PGW 134 may also include a number of additional features such as, for example, packet filtering, deep packet inspection, and subscriber charging support.", "Policy and charging rules node (PCRN) 136 may be a device that receives requests for application services, generates PCC rules, and provides PCC rules to the PGW 134 and/or other PCENs (not shown).", "PCRN 136 may be in communication with AN 150 via an Rx interface.", "PCRN 136 may receive a service request in the form of an AA-Request (AAR) 160 from AN 150 .", "PCRN 136 may also be in communication with SGW 132 and PGW 134 via a Gxx and a Gx interface, respectively.", "PCRN 136 may receive a service request in the form of a credit control request (CCR) 170 from SGW 132 or PGW 134 .", "In various embodiments, AAR 160 and CCR 170 may represent two independent service requests to be processed separately, while in other embodiments, AAR 160 and CCR 170 may carry information regarding a single service request and PCRN 136 may create at least one PCC rule based on the combination of AAR 160 and CCR 170 .", "In various embodiments, PCRN 136 may be capable of handling both single-message and paired-message service requests.", "Upon creating a new PCC rule or upon request by the PGW 134 , PCRN 136 may provide a PCC rule to PGW 134 via the Gx interface.", "In various embodiments, such as those implementing the PMIP standard for example, PCRN 136 may also generate QoS rules.", "Upon creating a new QoS rule or upon request by the SGW 132 , PCRN 136 may provide a QoS rule to SGW 132 via the Gxx interface.", "As will be discussed in further detail below, PCRN 136 may receive a request to update a PCC rule with new filters.", "PCRN 136 may receive an update CCR 170 from PGW 134 indicating one or more new filters and a reference filter.", "PCRN 136 may determine an existing PCC rule and related information based on the reference filter.", "PCRN 136 may determine new QoS-information for the PCC rule using information regarding the new filters and existing filters.", "PCRN 136 may also control for removed filters and flow direction.", "PCRN 136 may generate a new PCC rule to replace the existing PCC rule.", "Subscription profile repository (SPR) 138 may be a device that stores information related to subscribers to the subscriber network 100 .", "Thus, SPR 138 may include a machine-readable storage medium such as read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and/or similar storage media.", "SPR 138 may be a component of PCRN 136 or may constitute an independent node within EPC 130 .", "Data stored by SPR 138 may include an identifier of each subscriber and indications of subscription information for each subscriber such as bandwidth limits, charging parameters, subscriber priority, and subscriber service preferences.", "Packet data network 140 may be any network for providing data communications between user equipment 110 and other devices connected to packet data network 140 , such as AN 150 .", "Further, packet data network 140 may provide, for example, phone and/or Internet service to various user devices in communication with packet data network 140 .", "Application Node (AN) 150 may be a device that provides an application service to user equipment 110 .", "Thus, AN 150 may be a server or other device that provides, for example, streaming video service to user equipment 110 .", "AN 150 may further be in communication with the PCRN 136 of the EPC 130 via an Rx interface.", "When AN 150 is to begin providing application service to user equipment 110 , AN 150 may generate a service request message, such as an AA-Request (AAR) according to the Diameter protocol, to notify the PCRN 136 that resources should be allocated for the application service.", "Such an service request message may include information such as an identification of the subscriber using the application service and an identification of the particular SDFs and filters that must be established within an internet protocol connectivity access network (IP-CAN) session in order to provide the requested service.", "AN 150 may communicate such an service request to the PCRN via the Rx interface 215 .", "Four examples will be described below illustrating embodiments that set the APN-AMBR in various situations.", "FIG. 2 illustrates a first example of message flow regarding APN-AMBR.", "In this example, the PGW 134 sends a CCR without the APN-AMBR DL/UL AVPs (download/upload attribute value pairs) or QCI_9 maximum bit rate download/upload (MBR DL/UL) AVPs to the PCRN 136 .", "The PCRN 136 sends a SPR profile request to the SPR 138 to request the APN-AMBR and MBR DL/UL information of the subscriber.", "The SPR 138 sends a response to the PCRN 136 indicating that the APN-AMBR limit DL/UP=30 Mbps and that the QCI_9 MBR DL/UL=60 Mbps.", "The PCRN 136 determines that the primary bearer QCI_9 MBR DL/UL value should be 30 Mpbs based upon the APN-AMBR limit of 30 Mbps even though the subscriber has an authorized QCI_9 MBR DL/UL=60 Mbps.", "In this case the lower APN-AMBR value is the limiting value and hence becomes the limit.", "The PCRN 136 then sends a CCA message indicating that the QCI_9 MBR DL/UL=30 Mbps and does not specify an APN-AMBR because there was no APN-AMBR specified in the CCR received from the PGW 134 .", "In the above description as well as the descriptions below, the CCR and CCA messages may be initialization messages or modification messages.", "FIG. 3 illustrates a second example of message flow regarding APN-AMBR.", "In this example, the PGW 134 sends a CCR with the APN-AMBR DL/UL=50 Mbps and the QCI_9 MBR DL/UL 50 Mbps to the PCRN 136 .", "The PCRN 136 sends a SPR profile request to the SPR 138 to request the APN-AMBR and MBR DL/UL information of the subscriber.", "The SPR 138 sends a response to the PCRN 136 indicating that the APN-AMBR limit DL/UL=60 Mbps and that the QCI_9 MBR DL/UL=30 Mbps.", "The PCRN 136 determines that the APN-AMBR value should be 60 mbps based upon the subscribers APN-AMBR value.", "The PCRN 136 determines that the primary bearer QCI_9 MBR DL/UL value should be 30 Mpbs based upon the QCI_9 MBR DL/UL limit of 30 Mbps even though the subscriber has an authorized APN-AMBR=60 Mbps.", "In this case the lower QCI_9 MBR DL/UL value is the limiting value and hence becomes the limit.", "The PCRN 136 then sends a CCA message indicating that the QCI_9 MBR DL/UL=30 Mbps and that the APN-AMBR=60 Mbps.", "FIG. 4 illustrates a third example of message flow regarding APN-AMBR.", "In this example, the PGW 134 sends a CCR without the APN-AMBR DL/UL AVPs (download/upload attribute value pairs) or QCI_9 MBR DL/UL AVPs to the PCRN 136 .", "The PCRN 136 determines that an operator policy rule action sets the APN-AMBR=100 Mbps.", "The PCRN 136 sends a SPR profile request to the SPR 138 to request the APN-AMBR and MBR DL/UL information of the subscriber.", "The SPR 138 sends a response to the PCRN 136 indicating that the APN-AMBR limit DL/UP=30 Mbps and that the QCI_9 MBR DL/UL=60 Mbps.", "The PCRN 136 determines that the APN-AMBR value should be 100 Mbps based upon the operator policy rule.", "The PCRN 136 determines that the primary bearer QCI_9 MBR DL/UL value should be 60 Mpbs based upon the QCI_9 MBR DL/UL limit of 60 Mbps even though the subscriber has an authorized APN-AMBR=30 Mbps.", "In this case the APN-AMBR value has been set to 100 Mpbs so the subscriber QCI_9 MBR DL/UL value of 60 Mbps is the limiting value and hence becomes the limit.", "The PCRN 136 then sends a CCA message indicating that the QCI_9 MBR DL/UL=60 Mbps and that the APN-AMBR=100 Mbps.", "FIG. 5 illustrates a fourth example of message flow regarding APN-AMBR.", "This example begins the same as that in FIG. 3 .", "The PGW 134 sends a CCR with the APN-AMBR DL/UL=50 Mbps and the QCI_9 MBR DL/UL 50 Mbps to the PCRN 136 .", "The PCRN 136 sends a SPR profile request to the SPR 138 to request the APN-AMBR and MBR DL/UL information of the subscriber.", "The SPR 138 sends a response to the PCRN 136 indicating that the APN-AMBR limit DL/UL=60 Mbps and that the QCI_9 MBR DL/UL=30 Mbps.", "The PCRN 136 determines that the APN-AMBR value should be 60 mbps based upon the subscribers APN-AMBR value.", "The PCRN 136 determines that the primary bearer QCI_9 MBR DL/UL value should be 30 Mpbs based upon the QCI_9 MBR DL/UL limit of 30 Mbps even though the subscriber has an authorized APN-AMBR=60 Mbps.", "In this case the lower QCI_9 MBR DL/UL value is the limiting value and hence becomes the limit.", "The PCRN 136 then sends a CCA message indicating that the QCI_9 MBR DL/UL=30 Mbps and that the APN-AMBR=60 Mbps.", "Next, the subscriber profile APN-AMBR is changed to 1 Mbps from 60 Mbps.", "The SPR 138 sends a SPR update notification to the PCRN 136 .", "The PCRN determines that the new subscriber APN-AMBR of 1 Mbps is now the limiting factor for the session.", "Accordingly, the PCRN 136 then sends a RAR message indicating that the QCI_9 MBR DL/UL=1 Mbps and that the APN-AMBR=1 Mbps FIG. 6 illustrates a method used by the PCRN to determine the AN-AMBR and MBR DL/UL values for a GPRS session.", "The method begins at step 605 .", "The PCRN 136 first receives CCR for a GPRS IP-CAN session request 610 .", "Next, the PCRN 136 determines if an operator policy rule action for the APN-AMBR has been specified 615 .", "If not, the PCRN 136 next determines if the CCR includes an APN-AMBR 620 .", "If not, then the PCRN sets the GPRS session MBR DL/UL to the lowest of the subscriber APN-AMBR and the subscriber MBR DL/UL 625 .", "The PCRN 136 then sends a CCA message to the PGW 134 with the selected MBR DL/UL value and without an APN-AMBR value 630 .", "The method then ends at 635 .", "If an operator policy rule action for the APN-AMBR has been specified 615 , the PCRN sets the GPRS session APN-AMBR to the APN-AMBR value specified by the operator policy rule action 645 .", "Next, the PCRN 136 sets the GPRS session MBR DL/UL to the lowest of the operator specified APN-AMBR and the subscriber MBR DL/UL 650 .", "The PCRN 136 then sends a CCA message to the PGW 134 with the selected APN-AMBR and MBR DL/UL values 655 .", "The method then ends at 635 .", "If the PCRN 136 determines that the CCR includes an APN-AMBR 620 , the PCRN 136 sets the GPRS session APN-AMBR to the subscriber APN-AMBR value 655 .", "The PCRN 136 then sets the GPRS session MBR DL/UL to the lowest of the subscriber APN-AMBR and the subscriber MBR DL/UL 670 .", "The PCRN 136 then sends a CCA message to the PGW 134 with the selected APN-AMBR and MBR DL/UL values 655 .", "The method then ends at 635 .", "The method described in FIG. 6 may also be used when the subscriber APN-AMBR is updated.", "In such a case, the PCRN would receive a SPR update notification at 610 .", "Further, the PCRN 136 would send a RAR message to the PGW 134 instead of a CCA message to update the APN-AMBR and MBR DL/UL values at steps 630 and 655 .", "Otherwise, the APN-AMBR and MBR DL/UL values will be selected in the same manner.", "It should be apparent from the foregoing description that various exemplary embodiments of the invention may be implemented in hardware.", "Furthermore, various exemplary embodiments may be implemented as instructions stored on a machine-readable storage medium, which may be read and executed by at least one processor to perform the operations described in detail herein.", "A machine-readable storage medium may include any mechanism for storing information in a form readable by a machine, such as a personal or laptop computer, a server, or other computing device.", "Thus, a tangible and non-transitory machine-readable storage medium may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and similar storage media.", "Further, as used herein, the term “processor”", "will be understood to encompass a microprocessor, field programmable gate array (FPGA), application-specific integrated circuit (ASIC), or any other device capable of performing the functions described herein.", "It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative circuitry embodying the principles of the invention.", "Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in machine readable media and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.", "Although the various exemplary embodiments have been described in detail with particular reference to certain exemplary aspects thereof, it should be understood that the invention is capable of other embodiments and its details are capable of modifications in various obvious respects.", "As is readily apparent to those skilled in the art, variations and modifications can be effected while remaining within the spirit and scope of the invention.", "Accordingly, the foregoing disclosure, description, and figures are for illustrative purposes only and do not in any way limit the invention, which is defined only by the claims." ]
BACKGROUND OF THE INVENTION 1. Field of the Invention The invention pertains to large-scale integrated logic array networks and particularly to such networks employing logic array structures having standardized form and dimensions. 2. Description of the Prior Art Prior art LSI logic networks which employ array structured logic usually contemplate shared external control of individual arrays in each operating cycle. In certain applications, however, small autonomously sequenced array modules are considered more efficient; for instance, in channel or input/output adapter sections of data processing systems or in distributed processing networks. It is also generally known that array structured logic is most useful as a substitute for randomly connected logic, irrespective of considerations of expense and design complexity, in applications involving frequent engineering change or low volume production of structurally similar but logically different parts. The universal logic module structure to be described herein makes it possible to construct a large variety of autonomously sequenced array networks having logically distinct operation repertoires from arrays having extensively standardized form, dimensions and fabrication process handling. SUMMARY OF THE INVENTION The subject universal logic module comprises standardly dimensioned and interconnected logic and storage arrays subject to unitized large scale integration packaging. Module fabrication is extensively standardized, except for cross-point personalization of the logic arrays when these arrays have read-only form. With more expensive writable logic arrays the cross-point connections may be standardized and offset to some extent the additional logic hardware and software expense. The internal conduction and connection elements in each module form several discrete cyclic signal manipulation paths, or loops, characterized by a capability to cyclically shift signals between loops. The storage array comprises plural registers having common read/write and address selection coupling to these loops. The logic and storage arrays are cooperative to perform combinational and sequential logical sum and product translation operations on signals circulating in the loops. Each module comprises integral gating circuits for input/output coupling to an external bus which may be shared by multiple modules for distributed or parallel processing usage. The logic arrays, which as indicated above are configured as read-only structures for the sake of economy, are adapted to provide a variety of cyclic sequences of operations subject either to external or internal (autonomous) control of operation sequencing in individual cycles. The potential sequence control repertoire of a module includes interrupts, resets, multi-sequence conditional branches, and data manipulations (addition, multiplication, etc.). Interruptions are effected by saving (and later reassembling) status signal states, which represent "next cycle" input stimuli to the logic array and the address controls of the storage array, in a predetermined address location of the storage array. This requires special manipulation of the "saved" address status and address signal designating the saving locations; especially when the operation being interrupted is itself an interruption of another operation. The foregoing and other features of the invention, as well as objectives thereof, will be appreciated from the following detailed description. DESCRIPTION OF THE DRAWINGS FIG. 1 schematically illustrates the universal logic module of the present invention; FIG. 2 graphically illustrates the cycle timing of said module; FIG. 3 illustrates a typical operation repertoire of a subject module; FIGS. 4-6 illustrate typical information signal parameters utilized in the subject module; FIGS. 7-10 schematically illustrate unidirectional cross-point connection configurations in the logic array of a subject module for effecting column shifting, logic manipulation, logical exclusive OR-ing and counting operations; FIG. 11 illustrates autonomous sequencing of a typical subject module organized for byte processing in cooperation with other autonomous modules, whereby 4 byte words are additively manipulated in 4 modules with inter-module carry information transfer; FIG. 12 illustrates interruption operation sequencing of a subject module; FIG. 13 illustrates a multi-module network; and FIG. 14 indicates use of redundant bussing elements to circumvent faulty internal operational elements of modules. DETAILED DESCRIPTION 1. General Organization Referring to FIGS. 1-6, a subject universal logic module, ULM comprises logic array section 1 and storage array section 2 (also designated STACK). The logic array may comprise discrete AND array and OR array sections 1a and 1b as indicated in FIG. 1. The dimensions of the storage array are small by comparison to those of the logic array. A typical logic array as presently contemplated would have several hundred rows and 100 or more columns (i.e. in excess of 20,000 "stored" cross-point coupling bit states). A typical storage array as presently contemplated would have capacity to store eight 32 bit words subject to random access (i.e. bit storage capacity of 256 bits). Storage array address selection is controlled via a decoding network 2b which translates three digit address codes at address selection inputs 2a into selection control on a unique one of eight word storage positions. Address inputs to 2a are supplied via latched outputs 1b1 of logic array section 1b. Module cycle timing is governed by clock signals CLA, CLB, CLC, CLD supplied by a clock network CLK indicated conceptually at 5. In actuality the clock signals may be developed either internally by integral module circuits or externally by common circuits coupled to several modules via the external bus 7. Signal conduction connections between STACK output latches 2c and respectively positioned logic array input gates 1a1 represent a first signal circulation path designated INNER LOOP. Similarly conduction connections between the indicated subsets of array output latches 1b1 and array input latches 1a1 define a second circulation path designated OUTER LOOP. Each line, between logic 1 and STACK 2 and between 1b1 and gates 1a1 actually represents multiple parallel signal conduction paths. Referring to FIGS. 1 and 2 in the cycle phase associated with "on" state of CLA contents of a selected STACK address are read out and latched in output latches 2c. In the cycle stage associated with activation of CLB latches 2c and previous cycle outputs of logic array section 1b, the latter held in latches 1b1, are connected to respective input columns of array section 1a to provide input (argument) stimuli for logical manipulation. Simultaneously external stimuli signals may be applied to other respective columns of array 1, via the external bus 7 and externally selected EXTERNAL IN gates, the latter integrally contained in the module. In this same stage internal reset and interrupt selection control is applied. In cycle phase CLC outputs of array section 1b are latched in array output latches 1b1. Finally, in cycle stage CLD signals held in respective array output latches 1b1 may be selectively transferred to the external bus 7, via integrally contained EXTERNAL OUT gates, and contents of other respective latches 1b1 may be stored in the STACK at the address designated by respective signals at addressing interface 2a. In each cycle phase CLB in which the actual logical manipulation occurs, input stimuli signals applied to array section 1a (from the internal loop, the reset control paths and/or the external bus input gating path) may have "logical data" and/or "logical control" significance. Logical control input stimuli are used both to determine the specific manipulation of the logical data stimuli in the current cycle and to establish logical control stimuli of the next cycle. The manner in which this sequence control is effected will be explained below. For the present it should be understood at least that the following operation sequence may occur in any cycle: (1) a STACK word may be read out and latched; (2) the latched STACK output and a part of the previous cycle output of array 1 may be applied in parallel to respective column inputs of array 1, respectively via the INNER LOOP and OUTER LOOP, and logically manipulated (translated) by array 1; when appropriate, external signals may be supplied concurrently to array 1 via respective EXTERNAL IN conduction and gating paths; when appropriate reset and interrupt control initiating signals may be supplied via other respective paths; (3) outputs of array 1 may be latched at 1b1; (4) latched outputs at 1b1 coupling to the INNER LOOP may be selectively written into the STACK and outputs coupling to the OUTER LOOP may be connected via the EXTERNAL OUT gating path to the bus 7. It should also be understood that in each cycle plural logical translations may be performed by the array 1, including translations to determine the control stimuli for the next cycle, and that the control and data stimuli may be selectively supplied to array 1 via any of the available input conduction paths (EXTERNAL IN, INNER LOOP, OUTER LOOP, INTERNAL RESET/INTERRUPT). 2. Operation Repertoire/Capability Before considering details of module construction it would be useful to understand the operational capabilities of the module organization just described. FIGS. 3-6 indicate that such modules are capable of being configured (by personalization of array sections 1a, 1b) to load external information in selected STACK locations, receive initial external control and thereafter operate autonomously over several cycles to perform various data processing operations (e.g. addition, shifting, conditional branching, interruption, etc.) relative to information stored in the STACK. Referring to FIG. 3 external and internal control argument parameters listed in FIGS. 4-6 are useful to condition the logic array cyclically to perform storage and logic operations (translation, shifting, formation of select logical sums of select logical products, etc.), relative to parallel signal stimuli on the INNER LOOP and OUTER LOOP, and to condition the module to perform condition manifesting, sequence initiation and/or external input/output gating operations. Combinations of such cyclic operations may be linked selectively into autonomous sequences of varied form by the various branching, interrupting, and resetting translation control patterns of the logic array. Such sequences may be organized for accomplishing interruptible selective data processing functions (e.g. addition, multiplication, division, status storage incidental to interruption, restoration of interrupted control states from stored status, and resetting or initializing of module/STACK states). This in effect permits each module to be configured to operate autonomously as a selectively programmed mini-processor with distinctively specialized or personalized operation capabilities and repertoire. 3. Array Construction/Specific Operations FIGS. 1 and 7-9 illustrate logic array constructions for implementating the foregoing operations relative to binary signals supplied at 1a1. FIG. 1 illustrates typical cross-point coupling constructions at row i and various selected columns of logic array 1. Triangular shading as at 15 in array section 1a represent unidirectional logical OR coupling connections from respective intersecting column conduction paths (ac j , ac k , . . . ) to the respective row conduction path r i . Intersections such as 17 which do not have triangular shading are understood to have respective column conductors effectively or logically decoupled from row conductor r i . Thus the signal on path r i in section 1a represents the logical OR of only the coupled input argument signal functions transferred through the couplings 15 to that path. The column conductors of array 1a receive the true and complement component signals of each input argument to be processed by the array. Alternatively, input arguments may be transferred through discrete decoding logic to form the requisite column inputs. Each row conduction path r i in logic array section 1a couples to a corresponding extended row conduction path of array section 1b via a respective inverting element I i . The signal output of each inverter I i thereby represents the logical NOR of signals on the column input conduction paths of array 1a received via connections 15 and r i . Equivalently, the output of I i represents the logical AND of the logical inverses of the inputs received via couplings 15. Naturally by providing appropriate true and complement inputs to section 1a the output of any row inverter I i can be made to represent the logical AND of any select group of input arguments. Thus, it is seen that each row conduction path of section 1a can be configured to provide a unique logical AND signal translation (minterm) of an associated select sub-group of input argument of stimuli signals relative to the group of all input stimuli signals presented to gates 1a1 of section 1a. Each row conduction path in array section 1b couples to one or more selected column conduction paths of section 1b via "OR coupling" connections indicated symbolically by trangular shading as at 19; distinguished from non-connections symbolically indicated by absence of shading as at 21. Any column conduction path in 1b may be coupled to a plurality of rows and thereby provide an output which represents a logical-OR of signals received from respectively coupled row conduction paths in 1b; i.e. a select logical sum of select logical products of input stimuli or argument signals received by array section 1a. 3a. Shifting In a simple translating or shifting operation (FIG. 7) signal representations of inverses of data functions to be shifted (shift data arguments) and of not shown inverses of associatively paired shift control operators (shift control arguments) are received on appropriate columns of array section 1a. Associated (paired) shift data and shift control arguments are NOR coupled in respective pairs via respectively configured row coupling paths of section 1a and respective output column conduction paths in section 1b to provide for transfers of desired "shifted" output data representations in respectively associated latches 1b1. The activated column conduction paths in 1b are coupled exclusively to singular respective row conduction paths during such operations due to the shift control arguments used and the logic array construction. 3b. Holding A special case of shifting is circulation of a data bit signal (or signals) from a latch (or latches 1b1) through the logic array into the same latch (or latches) 1b1. In such operations (termed "holding"), the logic array and associated inter-array conduction paths are effectively employed as recirculating delay or storage network(s). 3c. Logical ANDing FIG. 8 indicates that logical ANDing of two (or more) "AND arguments" is executed by controlled NOR translation of input signals representative of the logical inverses of the AND arguments through a suitably configured row conduction path of array 1. Preparation of this path is by one or more of the input argument signals. The outcome is a signal transferred to respectively coupled columns of array section 1b representative of the AND of the input signals. 3d. Exclusive OR FIG. 9 shows that the logical Exclusive OR of two or more input arguments (in general selected logical sum of selected logical products) Is obtained utilizing two or more appropriately patterned rows of the array. Each of these rows has couplings patterned to form a logical product of the inverse of an associated one of a group of input "data" arguments with true representation(s) of the other "data" argument(s) of the group. The row (product) functions are logically summed (OR'd) in an appropriately coupled (and, if relevant, positioned) column of array section 1b, which provides an output representative of the Exclusive OR of the grouped inputs. 3e. Counting FIG. 10 shows that information representing a count may be incremented (or decremented) by translation through a "matching" logic array row having select output couplings to OR array columns positioned according to the desired incremented (or decremented) count value. 3f. Addition An organizational structure for combining plural cyclic operations to accomplish autonomous addition of two word operands is explained with reference to FIGS. 1-11. By extension organizations for similar operations of multiplication, division, matrix manipulation, etc. will be understood. Four modules connected via a multi-conductor bus autonomously perform addition operations on pre-loaded denominationally ordered byte (quarter-word) segments of augend and addend words. Group (byte) carry and group propagate signal functions are exchanged between modules via the bus. Received group functions are used selectively by recipient modules to form full addition result bytes. Augend and addend bytes to be added are pre-loaded into each module together with initial control intelligence defining byte denominational order. The source of such intelligence typically would be another module communicating with the adding modules via the external bus. Initial control provides for selection of EXTERNAL IN gates (FIG. (1) of individual adding modules, selection of STACK loading addresses and selection of an initial OUTER LOOP control signal state for initiating the desired autonomous operation. When the four adding modules have been loaded (e.g. in eight externally controlled loading cycles) they may proceed concurrently under autonomous control to carry out addition operations on respectively stored bytes. An external "go-ahead" signal given to all adding modules is translated through arrays 1 into initial OUTER LOOP control signals serving to initiate associated autonomous sequences in respective modules. The following sequence of operations occurs in each module: a. one of the bytes to be added (e.g. the augend byte) is retrieved from the STACK and shifted (FIG. 7) through the logic array into selected latches 1b1 interfacing with the OUTER LOOP (FIG. 1). Simultaneously next cycle sequence control factors f, s, A, . . . (including control initiating intelligence related to the denominational orders of respectively loaded bytes) are established in outer loop latches 1b1 (the requisite initial control factors and STACK addressing functions for accomplishing these operations having been previously received; e.g. by translation of the previously given external "go-ahead" at CLB-CLC of the previous cycle). The translation to next cycle control may include counting modification of one or more sequence control count factors (e.g. "s" may be incremented), accomplished by translation of the factor digits through logic array rows patterned according to the required counting algorithm (FIG. 10). b. In the next cycle (cycle b, FIG. 11) the addened byte is fetched from the STACK to the INNER LOOP and additively combined (Exclusive OR'd) bit for bit with the augend byte circulating in the OUTER LOOP. At CLD of this cycle the half-add result is stored in the STACK space (y) vacated by the addend byte and the bit carries are positioned to replace respective augend bits at the OUTER LOOP interface 1b1. Also at CLD group (byte) carry and group propagate signal functions, developed and latched in other OUTER LOOP interface latches 1b1, are gated to external bus conduction paths associated with the denominational byte handling orders originally assigned to respective modules. The control status of the OUTER LOOP is translatively modified in this cycle for next cycle control. Assuming that bytes have eight bits and STACK registers hold 32 bits, in many systems it will be feasible to load the addend and augend bytes into one-half of a STACK register and simultaneously retrieve the two bytes for half addition exclusively thru the INNER LOOP path. When this is feasible step a) above may be eliminated. c. In the next cycle (cycle c, FIG. 11) the half-add result bits are added to respectively ordered bit carries. The lowest order half-add result bit is selectively augmented as a function of the group propagate and group carry information received via the bus from lower order modules (these being implicitly ordered by virtue of their conduction path positions on the bus). The augmented partial result is stored in the STACK space vacated by the half-add result. Bit carries resulting from this cycle are preserved in the OUTER LOOP positions vacated by the previous bit carries and OUTER LOOP control factors for this cycle are translated into factors appropriate for next cycle control. d. In the next cycle (cycle d, FIG. 11) the "full add" final result is formed by bit-wise parallel addition of the retained bit carries and the last stored partial result. The final result is stored in the STACK space vacated by the previous cycle partial result and each module gates out completion signal on a separate external bus conduction path associated with the respective byte order assignment of the module. Current cycle control is selectively translated into next cycle control utilizing condition status information supplied through the "CONDITIONS, STATUS & INTERRUPTS" conduction paths (in effect a "conditional branch" is taken). 3g. Interruption FIG. 12 shows how interruption of autonomous sequencing is carried out and how plural interruptions may be hierarchically nested. With each interruption OUTER LOOP signal conditions (status) established at CLC of the last cycle of interrupted activity are stored (saved) in a predetermined STACK address location associated with the nesting count factor N. The saved status is subject to subsequent retrieval and re-alignment in respective OUTER LOOP positions for causing the interrupted action to be resumed without loss of function. The operational sequence is as follows: a. Upon responsive recognition (logical translation) of a condition (external or internal) requiring interruption of a current activity, OUTER LOOP signal status [including the STACK address code signal at 2a (FIG. 1)] is stored (saved) in a predetermined STACK address and a signal (or signals) is (are) given to reset the condition causing the interruption. The saving address is determined in association with an incremented nesting count factor N, which is incremented when the interruption is initiated and decremented when the interrupting activity is completed. The number of module cycles needed to complete the status saving and incrementing of N depends principally upon the size (bit length) of the OUTER LOOP field which must be saved. The interrupted activity may itself be a "nested" interruption of another activity (FIG. 12) or it may be an original activity (level N = O) such as a stage of the addition process previously described. The logic of array 1 relative to accepting interruption or nested interruption could easily be prioritized (by patterning of appropriate cross-points) so that not all activities would be interruptible prior to a given cyclic stage of their completion. The status saving action is accomplished by translating the signal representing the interrupting condition (when permissible) into "next cycle interrupt control" status at suitable vacant OUTER LOOP conduction path interface positions, while the action normally initiated in this cycle is completed. In the next cycle N + is "generated" into STACK interfaces 2a by translation of current status (control) signals representative of N. Concurrently normal "next cycle" STACK address is shifted into the write-in path interface between 1b1 and the STACK. Concurrently up to 29 other normal next cycle control status bit signals may be shifted into this path and saved together with the normal next address. Alternately, several cycles of holding and shifting (and STACK address manipulation) may be used to simplify the saving shifts or to accommodate the saving of more than thirty-two status bits. b. While the saving operation(s) is (are) executed the OUTER LOOP control factors are concurrently translated into control signals suitable for initiating the first cycle of processing activity for which the interruption was taken (for example, testing of a possibly erroneous addition operand or result bit utilizing, a "masking" row in the logic array to select the desired bit). c. Upon conclusion of the interruption processing activity assuming that further interruption have not been taken) N is decremented and saved status of the interrupted activity is restored by reverse shifting of the saved bits relative to interface 1b1 (i.e. status of the next lower ranked interruption process is restored if the decremented value of N is not zero or status of a lowest ranked data processing activity is restored if decremented N is zero) to produce the parallel signal states at 2a and other OUTER LOOP positions required for continuation of the interrupted activity. If necessary or desirable one or more "holding" operations may be employed in a piecemeal (plural cycle) re-alignment of the saved status functions. 3h. Conditional Branches Logic array rows may be configured to condition branch sequence selection of next cycle control upon conditions manifested either externally (at the EXTERNAL IN gating interface, FIG. 1) or internally (at the INTERNAL CONDITIONS, AESETS . . . interface, to array 1a, (FIG. 1). For this purpose the conduction paths conveying such conditions are coupled to translation rows of array 1 arranged to responsively translate the manifested condition (or combination of conditions) into appropriate OUTER LOOP control status for effecting the desired sequence branch. Discrete CONDITION latches separate from array latches 1B1 may be used to retain separately occurring conditions for combinational influencing of branch selection. 3i. Waiting/Idling Holding shifts of OUTER LOOP states may be used to provide waiting or idling cycles of operation (e.g. to enable several modules to coordinate a distributed processing operation). Logic array rows may also be patterned to permit maintenance of condition signals in selected OUTER LOOP conduction paths concurrent with other logical processing operations for controlling conditional branching (see "Holding" supra). 3j. Resets Reset operations "clear" the STACK (zeros written into predetermined STACK locations) and establish initial idling conditions in the OUTER LOOP preparational to conditional branching to specific processing sequence action. 4. Multi-module Configurations Multiple modules of the form described above may be interconnected via a common bussing highway to provide either distributed processing capability or switchable configurations for circumventing faulty module constructions. Individual conduction paths B j of the bus connect (FIGS. 13, 14) via corresponding EXTERNAL conduction path gating elements to corresponding input or output coordinate column conduction paths in each module ULMi. For each "original" bus conduction path element B j there may be provided a corresponding redundant element RB j (FIG. 14) subject to switched selection relative to B j in each module. In each module the switch path associated with a redundant bus element may be made connectable to redundant column and row elements of the respective logic array and the latter may be structured to duplicate the functions of column and row elements connectable to B j ; whereby a fault contained in a module conduction path associated with B j can be circumvented, without altering the module function in respect to the malfunctioning path. The connection path selection may be accomplished manually during production testing of modules. Thus, by means of such redundant constructions and switching the module manufacturing process may be made fault tolerant; so that imperfect modules may be used. 5. Multiple Addressing of Stack It may be useful in some module configurations to provide plural signal paths to the address selection controls of the STACK with switching circuits to select between these paths in each cycle. Thus, the STACK addressing path (2a, FIG. 1) may be adapted to receive addressing stimuli from a selected one of several sources. These may include various different output fields of array section 1b, external input gates, and internal condition latches. Other selective addressing configurations will be apparent. Naturally in a module with alternate addressing paths, control of path selection requires additional circuitry but simplifies the control of address status storage in respect to interruption. 6. Testing of Modules In a multi-module network as discussed above the individual modules may be tested remotely. The test organization is as follows: A single test is generated to select a module and verify its operation. This test determines whether every bistable device can be set to both 0 and 1 states, and whether the words in the logic array operate correctly; e.g. that the array performs the sum of products correctly. The test may access several logic words in parallel, provided there is unique differentiation of each word tested in the OR-array output. When plural modules are logically identical and interconnected by a common bus the same test sequence can be performed sequentially for each module, and the checking of the results of the tests can be performed by comparing results produced by different modules. Majority logic can be used to identify the source of any error. Common failures like bus failures may be verified by external hardware (oscilloscopes). 7. Module Fabrication a. Read Only Logic Array/Writeable STACK When the logic arrays have read-only structuring the modules may be identically handled in manufacture to form the STACK, the logic array structures other than crosspoint couplings, the inter-array internal conduction paths, the EXTERNAL IN and EXTERNAL OUT connection interfaces, the internal condition manifesting elements, and so forth. The process of manufacture may be any of the many well known LSI manufacturing processes in use today. The logic array cross-point couplings in particular rows may be made identical for all modules in a given line of modules. For instance if all such modules will have interruption capability the logic array rows providing the requisite logical shifting and STACK addressing functions may be identically located and formed in all modules. This leaves only the specialized functions (numerical arithmetic, matrix arithmetic, editing, sorting, etc.) to be implemented by specialized manufacturing handling of individual modules (or sets of modules). In such individualized handling crosspoints of logic array rows designated by the logic designer are given specialized cross-point coupling "personality" by means of specialized masks or selective step-and-repeat process handling. b. Writable Logic/Writable STACK By incorporating additional storage and gating structures at each logic array row cross-point, the logic array would be "writable" for "slow write/fast read" usage and the manufacturing process would be standardized for all modules. However, the personalization (slow write) of individual modules would require specialized program back-up and the expense of the additional structures would not be inconsequential. To some extent, however, these disadvantages could be offset by the additional flexibility offered by such modules. 8. Miscellaneous Module Organizations and Constructions Writable logic arrays may be constructed using state of the art bipolar OR FET technology. The function of the AND array is achieved by using a conventional storage bistable device with additional logic for the NOR operation. Read-only logic arrays can be achieved by provision of permanent unidirectional coupling devices or elements at the array cross-points. These devices may be diodes or transistors formed either selectively at selected cross-points during a masking stage in the fabrication process or at all cross-points subject to being open curcuited selectively after fabrication processing (e.g. by electrical or laser techniques). FET or bipolar transistors may be "personalized" selectively by varying the gate thickness (for FET devices), or the metalizing mask (for both FET and bipolar). The logic design principle is based upon expressing desired primitive logic functions as sums of products. The structure of the universal logic module relies upon its logic capability to perform higher levels of functions by sequential autonomous operation. The design procedure requires the mapping of the primitive functions into the array row cross-points with feedback from the OR-array providing sequential control of selection of those primitives. This requires a control field (column) associated with the "addressing" of each primitive function. If necessary to define control fields that select combinations of primitives simultaneously this can be achieved by using "dont-care" translational states in the AND array positions associated with addressing of such primitives. Selection of sequences is based upon provision of control field(s) which uniquely identify the sequence as well as individual sequence stages. Conclusion From the foregoing description it may now be appreciated that the described module provides the basis for providing families of identically dimensioned and identically organized array logic modules having autonomous operation control capability and providing a wide variety of different operations, within limits imposed by the dimensions chosen for the logic and storage array and the predetermined inter-array internal connections. Array dimensions are subject to selection, for a given family or line of modules, as a function of the available technology for large scale integration and the range or repertoire of useful functions contemplated for the complete line. While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
A universal array logic module featuring autonomous operation includes interconnected array structured logic and a small writable storage array. The module is subject to large scale integrated packaging as a standardly dimensioned unit (e.g. chip). The internal connections form discrete first and second internal circulation loops in one of which the storage array connects as a serial constituent randomly addressable by signals carried in the other loop. The storage array typically holds eight 32-bit words. The logic arrays may be read-only structures organized to perform arithmetic and translational logic manipulations under autonomous (internal) control. The module assembly includes integral input/output gating for transferring signals between an external bus and the internal loops. The logic array structure permits both external and internal control of cyclic operation. The operation repertoire includes interrupts, resets, and sequence branches. Interrupted status (loop signals) is saved in predetermined address locations of the storage array, requiring novel manipulation and storage of the address argument of the interrupted cycle. The logic arrays may be economically configured as read-only structures.
Identify the most important aspect in the document and summarize the concept accordingly.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention The invention pertains to large-scale integrated logic array networks and particularly to such networks employing logic array structures having standardized form and dimensions.", "Description of the Prior Art Prior art LSI logic networks which employ array structured logic usually contemplate shared external control of individual arrays in each operating cycle.", "In certain applications, however, small autonomously sequenced array modules are considered more efficient;", "for instance, in channel or input/output adapter sections of data processing systems or in distributed processing networks.", "It is also generally known that array structured logic is most useful as a substitute for randomly connected logic, irrespective of considerations of expense and design complexity, in applications involving frequent engineering change or low volume production of structurally similar but logically different parts.", "The universal logic module structure to be described herein makes it possible to construct a large variety of autonomously sequenced array networks having logically distinct operation repertoires from arrays having extensively standardized form, dimensions and fabrication process handling.", "SUMMARY OF THE INVENTION The subject universal logic module comprises standardly dimensioned and interconnected logic and storage arrays subject to unitized large scale integration packaging.", "Module fabrication is extensively standardized, except for cross-point personalization of the logic arrays when these arrays have read-only form.", "With more expensive writable logic arrays the cross-point connections may be standardized and offset to some extent the additional logic hardware and software expense.", "The internal conduction and connection elements in each module form several discrete cyclic signal manipulation paths, or loops, characterized by a capability to cyclically shift signals between loops.", "The storage array comprises plural registers having common read/write and address selection coupling to these loops.", "The logic and storage arrays are cooperative to perform combinational and sequential logical sum and product translation operations on signals circulating in the loops.", "Each module comprises integral gating circuits for input/output coupling to an external bus which may be shared by multiple modules for distributed or parallel processing usage.", "The logic arrays, which as indicated above are configured as read-only structures for the sake of economy, are adapted to provide a variety of cyclic sequences of operations subject either to external or internal (autonomous) control of operation sequencing in individual cycles.", "The potential sequence control repertoire of a module includes interrupts, resets, multi-sequence conditional branches, and data manipulations (addition, multiplication, etc.).", "Interruptions are effected by saving (and later reassembling) status signal states, which represent "next cycle"", "input stimuli to the logic array and the address controls of the storage array, in a predetermined address location of the storage array.", "This requires special manipulation of the "saved"", "address status and address signal designating the saving locations;", "especially when the operation being interrupted is itself an interruption of another operation.", "The foregoing and other features of the invention, as well as objectives thereof, will be appreciated from the following detailed description.", "DESCRIPTION OF THE DRAWINGS FIG. 1 schematically illustrates the universal logic module of the present invention;", "FIG. 2 graphically illustrates the cycle timing of said module;", "FIG. 3 illustrates a typical operation repertoire of a subject module;", "FIGS. 4-6 illustrate typical information signal parameters utilized in the subject module;", "FIGS. 7-10 schematically illustrate unidirectional cross-point connection configurations in the logic array of a subject module for effecting column shifting, logic manipulation, logical exclusive OR-ing and counting operations;", "FIG. 11 illustrates autonomous sequencing of a typical subject module organized for byte processing in cooperation with other autonomous modules, whereby 4 byte words are additively manipulated in 4 modules with inter-module carry information transfer;", "FIG. 12 illustrates interruption operation sequencing of a subject module;", "FIG. 13 illustrates a multi-module network;", "and FIG. 14 indicates use of redundant bussing elements to circumvent faulty internal operational elements of modules.", "DETAILED DESCRIPTION 1.", "General Organization Referring to FIGS. 1-6, a subject universal logic module, ULM comprises logic array section 1 and storage array section 2 (also designated STACK).", "The logic array may comprise discrete AND array and OR array sections 1a and 1b as indicated in FIG. 1. The dimensions of the storage array are small by comparison to those of the logic array.", "A typical logic array as presently contemplated would have several hundred rows and 100 or more columns (i.e. in excess of 20,000 "stored"", "cross-point coupling bit states).", "A typical storage array as presently contemplated would have capacity to store eight 32 bit words subject to random access (i.e. bit storage capacity of 256 bits).", "Storage array address selection is controlled via a decoding network 2b which translates three digit address codes at address selection inputs 2a into selection control on a unique one of eight word storage positions.", "Address inputs to 2a are supplied via latched outputs 1b1 of logic array section 1b.", "Module cycle timing is governed by clock signals CLA, CLB, CLC, CLD supplied by a clock network CLK indicated conceptually at 5.", "In actuality the clock signals may be developed either internally by integral module circuits or externally by common circuits coupled to several modules via the external bus 7.", "Signal conduction connections between STACK output latches 2c and respectively positioned logic array input gates 1a1 represent a first signal circulation path designated INNER LOOP.", "Similarly conduction connections between the indicated subsets of array output latches 1b1 and array input latches 1a1 define a second circulation path designated OUTER LOOP.", "Each line, between logic 1 and STACK 2 and between 1b1 and gates 1a1 actually represents multiple parallel signal conduction paths.", "Referring to FIGS. 1 and 2 in the cycle phase associated with "on"", "state of CLA contents of a selected STACK address are read out and latched in output latches 2c.", "In the cycle stage associated with activation of CLB latches 2c and previous cycle outputs of logic array section 1b, the latter held in latches 1b1, are connected to respective input columns of array section 1a to provide input (argument) stimuli for logical manipulation.", "Simultaneously external stimuli signals may be applied to other respective columns of array 1, via the external bus 7 and externally selected EXTERNAL IN gates, the latter integrally contained in the module.", "In this same stage internal reset and interrupt selection control is applied.", "In cycle phase CLC outputs of array section 1b are latched in array output latches 1b1.", "Finally, in cycle stage CLD signals held in respective array output latches 1b1 may be selectively transferred to the external bus 7, via integrally contained EXTERNAL OUT gates, and contents of other respective latches 1b1 may be stored in the STACK at the address designated by respective signals at addressing interface 2a.", "In each cycle phase CLB in which the actual logical manipulation occurs, input stimuli signals applied to array section 1a (from the internal loop, the reset control paths and/or the external bus input gating path) may have "logical data"", "and/or "logical control"", "significance.", "Logical control input stimuli are used both to determine the specific manipulation of the logical data stimuli in the current cycle and to establish logical control stimuli of the next cycle.", "The manner in which this sequence control is effected will be explained below.", "For the present it should be understood at least that the following operation sequence may occur in any cycle: (1) a STACK word may be read out and latched;", "(2) the latched STACK output and a part of the previous cycle output of array 1 may be applied in parallel to respective column inputs of array 1, respectively via the INNER LOOP and OUTER LOOP, and logically manipulated (translated) by array 1;", "when appropriate, external signals may be supplied concurrently to array 1 via respective EXTERNAL IN conduction and gating paths;", "when appropriate reset and interrupt control initiating signals may be supplied via other respective paths;", "(3) outputs of array 1 may be latched at 1b1;", "(4) latched outputs at 1b1 coupling to the INNER LOOP may be selectively written into the STACK and outputs coupling to the OUTER LOOP may be connected via the EXTERNAL OUT gating path to the bus 7.", "It should also be understood that in each cycle plural logical translations may be performed by the array 1, including translations to determine the control stimuli for the next cycle, and that the control and data stimuli may be selectively supplied to array 1 via any of the available input conduction paths (EXTERNAL IN, INNER LOOP, OUTER LOOP, INTERNAL RESET/INTERRUPT).", "Operation Repertoire/Capability Before considering details of module construction it would be useful to understand the operational capabilities of the module organization just described.", "FIGS. 3-6 indicate that such modules are capable of being configured (by personalization of array sections 1a, 1b) to load external information in selected STACK locations, receive initial external control and thereafter operate autonomously over several cycles to perform various data processing operations (e.g. addition, shifting, conditional branching, interruption, etc.) relative to information stored in the STACK.", "Referring to FIG. 3 external and internal control argument parameters listed in FIGS. 4-6 are useful to condition the logic array cyclically to perform storage and logic operations (translation, shifting, formation of select logical sums of select logical products, etc.), relative to parallel signal stimuli on the INNER LOOP and OUTER LOOP, and to condition the module to perform condition manifesting, sequence initiation and/or external input/output gating operations.", "Combinations of such cyclic operations may be linked selectively into autonomous sequences of varied form by the various branching, interrupting, and resetting translation control patterns of the logic array.", "Such sequences may be organized for accomplishing interruptible selective data processing functions (e.g. addition, multiplication, division, status storage incidental to interruption, restoration of interrupted control states from stored status, and resetting or initializing of module/STACK states).", "This in effect permits each module to be configured to operate autonomously as a selectively programmed mini-processor with distinctively specialized or personalized operation capabilities and repertoire.", "Array Construction/Specific Operations FIGS. 1 and 7-9 illustrate logic array constructions for implementating the foregoing operations relative to binary signals supplied at 1a1.", "FIG. 1 illustrates typical cross-point coupling constructions at row i and various selected columns of logic array 1.", "Triangular shading as at 15 in array section 1a represent unidirectional logical OR coupling connections from respective intersecting column conduction paths (ac j , ac k , .", ") to the respective row conduction path r i .", "Intersections such as 17 which do not have triangular shading are understood to have respective column conductors effectively or logically decoupled from row conductor r i .", "Thus the signal on path r i in section 1a represents the logical OR of only the coupled input argument signal functions transferred through the couplings 15 to that path.", "The column conductors of array 1a receive the true and complement component signals of each input argument to be processed by the array.", "Alternatively, input arguments may be transferred through discrete decoding logic to form the requisite column inputs.", "Each row conduction path r i in logic array section 1a couples to a corresponding extended row conduction path of array section 1b via a respective inverting element I i .", "The signal output of each inverter I i thereby represents the logical NOR of signals on the column input conduction paths of array 1a received via connections 15 and r i .", "Equivalently, the output of I i represents the logical AND of the logical inverses of the inputs received via couplings 15.", "Naturally by providing appropriate true and complement inputs to section 1a the output of any row inverter I i can be made to represent the logical AND of any select group of input arguments.", "Thus, it is seen that each row conduction path of section 1a can be configured to provide a unique logical AND signal translation (minterm) of an associated select sub-group of input argument of stimuli signals relative to the group of all input stimuli signals presented to gates 1a1 of section 1a.", "Each row conduction path in array section 1b couples to one or more selected column conduction paths of section 1b via "OR coupling"", "connections indicated symbolically by trangular shading as at 19;", "distinguished from non-connections symbolically indicated by absence of shading as at 21.", "Any column conduction path in 1b may be coupled to a plurality of rows and thereby provide an output which represents a logical-OR of signals received from respectively coupled row conduction paths in 1b;", "i.e. a select logical sum of select logical products of input stimuli or argument signals received by array section 1a.", "3a.", "Shifting In a simple translating or shifting operation (FIG.", "7) signal representations of inverses of data functions to be shifted (shift data arguments) and of not shown inverses of associatively paired shift control operators (shift control arguments) are received on appropriate columns of array section 1a.", "Associated (paired) shift data and shift control arguments are NOR coupled in respective pairs via respectively configured row coupling paths of section 1a and respective output column conduction paths in section 1b to provide for transfers of desired "shifted"", "output data representations in respectively associated latches 1b1.", "The activated column conduction paths in 1b are coupled exclusively to singular respective row conduction paths during such operations due to the shift control arguments used and the logic array construction.", "3b.", "Holding A special case of shifting is circulation of a data bit signal (or signals) from a latch (or latches 1b1) through the logic array into the same latch (or latches) 1b1.", "In such operations (termed "holding"), the logic array and associated inter-array conduction paths are effectively employed as recirculating delay or storage network(s).", "3c.", "Logical ANDing FIG. 8 indicates that logical ANDing of two (or more) "AND arguments"", "is executed by controlled NOR translation of input signals representative of the logical inverses of the AND arguments through a suitably configured row conduction path of array 1.", "Preparation of this path is by one or more of the input argument signals.", "The outcome is a signal transferred to respectively coupled columns of array section 1b representative of the AND of the input signals.", "3d.", "Exclusive OR FIG. 9 shows that the logical Exclusive OR of two or more input arguments (in general selected logical sum of selected logical products) Is obtained utilizing two or more appropriately patterned rows of the array.", "Each of these rows has couplings patterned to form a logical product of the inverse of an associated one of a group of input "data"", "arguments with true representation(s) of the other "data"", "argument(s) of the group.", "The row (product) functions are logically summed (OR'd) in an appropriately coupled (and, if relevant, positioned) column of array section 1b, which provides an output representative of the Exclusive OR of the grouped inputs.", "3e.", "Counting FIG. 10 shows that information representing a count may be incremented (or decremented) by translation through a "matching"", "logic array row having select output couplings to OR array columns positioned according to the desired incremented (or decremented) count value.", "3f.", "Addition An organizational structure for combining plural cyclic operations to accomplish autonomous addition of two word operands is explained with reference to FIGS. 1-11.", "By extension organizations for similar operations of multiplication, division, matrix manipulation, etc.", "will be understood.", "Four modules connected via a multi-conductor bus autonomously perform addition operations on pre-loaded denominationally ordered byte (quarter-word) segments of augend and addend words.", "Group (byte) carry and group propagate signal functions are exchanged between modules via the bus.", "Received group functions are used selectively by recipient modules to form full addition result bytes.", "Augend and addend bytes to be added are pre-loaded into each module together with initial control intelligence defining byte denominational order.", "The source of such intelligence typically would be another module communicating with the adding modules via the external bus.", "Initial control provides for selection of EXTERNAL IN gates (FIG.", "(1) of individual adding modules, selection of STACK loading addresses and selection of an initial OUTER LOOP control signal state for initiating the desired autonomous operation.", "When the four adding modules have been loaded (e.g. in eight externally controlled loading cycles) they may proceed concurrently under autonomous control to carry out addition operations on respectively stored bytes.", "An external "go-ahead"", "signal given to all adding modules is translated through arrays 1 into initial OUTER LOOP control signals serving to initiate associated autonomous sequences in respective modules.", "The following sequence of operations occurs in each module: a. one of the bytes to be added (e.g. the augend byte) is retrieved from the STACK and shifted (FIG.", "7) through the logic array into selected latches 1b1 interfacing with the OUTER LOOP (FIG.", "1).", "Simultaneously next cycle sequence control factors f, s, A, .", "(including control initiating intelligence related to the denominational orders of respectively loaded bytes) are established in outer loop latches 1b1 (the requisite initial control factors and STACK addressing functions for accomplishing these operations having been previously received;", "e.g. by translation of the previously given external "go-ahead"", "at CLB-CLC of the previous cycle).", "The translation to next cycle control may include counting modification of one or more sequence control count factors (e.g. "s"", "may be incremented), accomplished by translation of the factor digits through logic array rows patterned according to the required counting algorithm (FIG.", "10).", "b. In the next cycle (cycle b, FIG. 11) the addened byte is fetched from the STACK to the INNER LOOP and additively combined (Exclusive OR'd) bit for bit with the augend byte circulating in the OUTER LOOP.", "At CLD of this cycle the half-add result is stored in the STACK space (y) vacated by the addend byte and the bit carries are positioned to replace respective augend bits at the OUTER LOOP interface 1b1.", "Also at CLD group (byte) carry and group propagate signal functions, developed and latched in other OUTER LOOP interface latches 1b1, are gated to external bus conduction paths associated with the denominational byte handling orders originally assigned to respective modules.", "The control status of the OUTER LOOP is translatively modified in this cycle for next cycle control.", "Assuming that bytes have eight bits and STACK registers hold 32 bits, in many systems it will be feasible to load the addend and augend bytes into one-half of a STACK register and simultaneously retrieve the two bytes for half addition exclusively thru the INNER LOOP path.", "When this is feasible step a) above may be eliminated.", "c. In the next cycle (cycle c, FIG. 11) the half-add result bits are added to respectively ordered bit carries.", "The lowest order half-add result bit is selectively augmented as a function of the group propagate and group carry information received via the bus from lower order modules (these being implicitly ordered by virtue of their conduction path positions on the bus).", "The augmented partial result is stored in the STACK space vacated by the half-add result.", "Bit carries resulting from this cycle are preserved in the OUTER LOOP positions vacated by the previous bit carries and OUTER LOOP control factors for this cycle are translated into factors appropriate for next cycle control.", "d. In the next cycle (cycle d, FIG. 11) the "full add"", "final result is formed by bit-wise parallel addition of the retained bit carries and the last stored partial result.", "The final result is stored in the STACK space vacated by the previous cycle partial result and each module gates out completion signal on a separate external bus conduction path associated with the respective byte order assignment of the module.", "Current cycle control is selectively translated into next cycle control utilizing condition status information supplied through the "CONDITIONS, STATUS &", "INTERRUPTS"", "conduction paths (in effect a "conditional branch"", "is taken).", "3g.", "Interruption FIG. 12 shows how interruption of autonomous sequencing is carried out and how plural interruptions may be hierarchically nested.", "With each interruption OUTER LOOP signal conditions (status) established at CLC of the last cycle of interrupted activity are stored (saved) in a predetermined STACK address location associated with the nesting count factor N. The saved status is subject to subsequent retrieval and re-alignment in respective OUTER LOOP positions for causing the interrupted action to be resumed without loss of function.", "The operational sequence is as follows: a. Upon responsive recognition (logical translation) of a condition (external or internal) requiring interruption of a current activity, OUTER LOOP signal status [including the STACK address code signal at 2a (FIG.", "1)] is stored (saved) in a predetermined STACK address and a signal (or signals) is (are) given to reset the condition causing the interruption.", "The saving address is determined in association with an incremented nesting count factor N, which is incremented when the interruption is initiated and decremented when the interrupting activity is completed.", "The number of module cycles needed to complete the status saving and incrementing of N depends principally upon the size (bit length) of the OUTER LOOP field which must be saved.", "The interrupted activity may itself be a "nested"", "interruption of another activity (FIG.", "12) or it may be an original activity (level N = O) such as a stage of the addition process previously described.", "The logic of array 1 relative to accepting interruption or nested interruption could easily be prioritized (by patterning of appropriate cross-points) so that not all activities would be interruptible prior to a given cyclic stage of their completion.", "The status saving action is accomplished by translating the signal representing the interrupting condition (when permissible) into "next cycle interrupt control"", "status at suitable vacant OUTER LOOP conduction path interface positions, while the action normally initiated in this cycle is completed.", "In the next cycle N + is "generated"", "into STACK interfaces 2a by translation of current status (control) signals representative of N. Concurrently normal "next cycle"", "STACK address is shifted into the write-in path interface between 1b1 and the STACK.", "Concurrently up to 29 other normal next cycle control status bit signals may be shifted into this path and saved together with the normal next address.", "Alternately, several cycles of holding and shifting (and STACK address manipulation) may be used to simplify the saving shifts or to accommodate the saving of more than thirty-two status bits.", "b. While the saving operation(s) is (are) executed the OUTER LOOP control factors are concurrently translated into control signals suitable for initiating the first cycle of processing activity for which the interruption was taken (for example, testing of a possibly erroneous addition operand or result bit utilizing, a "masking"", "row in the logic array to select the desired bit).", "c. Upon conclusion of the interruption processing activity assuming that further interruption have not been taken) N is decremented and saved status of the interrupted activity is restored by reverse shifting of the saved bits relative to interface 1b1 (i.e. status of the next lower ranked interruption process is restored if the decremented value of N is not zero or status of a lowest ranked data processing activity is restored if decremented N is zero) to produce the parallel signal states at 2a and other OUTER LOOP positions required for continuation of the interrupted activity.", "If necessary or desirable one or more "holding"", "operations may be employed in a piecemeal (plural cycle) re-alignment of the saved status functions.", "3h.", "Conditional Branches Logic array rows may be configured to condition branch sequence selection of next cycle control upon conditions manifested either externally (at the EXTERNAL IN gating interface, FIG. 1) or internally (at the INTERNAL CONDITIONS, AESETS .", "interface, to array 1a, (FIG.", "1).", "For this purpose the conduction paths conveying such conditions are coupled to translation rows of array 1 arranged to responsively translate the manifested condition (or combination of conditions) into appropriate OUTER LOOP control status for effecting the desired sequence branch.", "Discrete CONDITION latches separate from array latches 1B1 may be used to retain separately occurring conditions for combinational influencing of branch selection.", "3i.", "Waiting/Idling Holding shifts of OUTER LOOP states may be used to provide waiting or idling cycles of operation (e.g. to enable several modules to coordinate a distributed processing operation).", "Logic array rows may also be patterned to permit maintenance of condition signals in selected OUTER LOOP conduction paths concurrent with other logical processing operations for controlling conditional branching (see "Holding"", "supra).", "3j.", "Resets Reset operations "clear"", "the STACK (zeros written into predetermined STACK locations) and establish initial idling conditions in the OUTER LOOP preparational to conditional branching to specific processing sequence action.", "Multi-module Configurations Multiple modules of the form described above may be interconnected via a common bussing highway to provide either distributed processing capability or switchable configurations for circumventing faulty module constructions.", "Individual conduction paths B j of the bus connect (FIGS.", "13, 14) via corresponding EXTERNAL conduction path gating elements to corresponding input or output coordinate column conduction paths in each module ULMi.", "For each "original"", "bus conduction path element B j there may be provided a corresponding redundant element RB j (FIG.", "14) subject to switched selection relative to B j in each module.", "In each module the switch path associated with a redundant bus element may be made connectable to redundant column and row elements of the respective logic array and the latter may be structured to duplicate the functions of column and row elements connectable to B j ;", "whereby a fault contained in a module conduction path associated with B j can be circumvented, without altering the module function in respect to the malfunctioning path.", "The connection path selection may be accomplished manually during production testing of modules.", "Thus, by means of such redundant constructions and switching the module manufacturing process may be made fault tolerant;", "so that imperfect modules may be used.", "Multiple Addressing of Stack It may be useful in some module configurations to provide plural signal paths to the address selection controls of the STACK with switching circuits to select between these paths in each cycle.", "Thus, the STACK addressing path (2a, FIG. 1) may be adapted to receive addressing stimuli from a selected one of several sources.", "These may include various different output fields of array section 1b, external input gates, and internal condition latches.", "Other selective addressing configurations will be apparent.", "Naturally in a module with alternate addressing paths, control of path selection requires additional circuitry but simplifies the control of address status storage in respect to interruption.", "Testing of Modules In a multi-module network as discussed above the individual modules may be tested remotely.", "The test organization is as follows: A single test is generated to select a module and verify its operation.", "This test determines whether every bistable device can be set to both 0 and 1 states, and whether the words in the logic array operate correctly;", "e.g. that the array performs the sum of products correctly.", "The test may access several logic words in parallel, provided there is unique differentiation of each word tested in the OR-array output.", "When plural modules are logically identical and interconnected by a common bus the same test sequence can be performed sequentially for each module, and the checking of the results of the tests can be performed by comparing results produced by different modules.", "Majority logic can be used to identify the source of any error.", "Common failures like bus failures may be verified by external hardware (oscilloscopes).", "Module Fabrication a. Read Only Logic Array/Writeable STACK When the logic arrays have read-only structuring the modules may be identically handled in manufacture to form the STACK, the logic array structures other than crosspoint couplings, the inter-array internal conduction paths, the EXTERNAL IN and EXTERNAL OUT connection interfaces, the internal condition manifesting elements, and so forth.", "The process of manufacture may be any of the many well known LSI manufacturing processes in use today.", "The logic array cross-point couplings in particular rows may be made identical for all modules in a given line of modules.", "For instance if all such modules will have interruption capability the logic array rows providing the requisite logical shifting and STACK addressing functions may be identically located and formed in all modules.", "This leaves only the specialized functions (numerical arithmetic, matrix arithmetic, editing, sorting, etc.) to be implemented by specialized manufacturing handling of individual modules (or sets of modules).", "In such individualized handling crosspoints of logic array rows designated by the logic designer are given specialized cross-point coupling "personality"", "by means of specialized masks or selective step-and-repeat process handling.", "b. Writable Logic/Writable STACK By incorporating additional storage and gating structures at each logic array row cross-point, the logic array would be "writable"", "for "slow write/fast read"", "usage and the manufacturing process would be standardized for all modules.", "However, the personalization (slow write) of individual modules would require specialized program back-up and the expense of the additional structures would not be inconsequential.", "To some extent, however, these disadvantages could be offset by the additional flexibility offered by such modules.", "Miscellaneous Module Organizations and Constructions Writable logic arrays may be constructed using state of the art bipolar OR FET technology.", "The function of the AND array is achieved by using a conventional storage bistable device with additional logic for the NOR operation.", "Read-only logic arrays can be achieved by provision of permanent unidirectional coupling devices or elements at the array cross-points.", "These devices may be diodes or transistors formed either selectively at selected cross-points during a masking stage in the fabrication process or at all cross-points subject to being open curcuited selectively after fabrication processing (e.g. by electrical or laser techniques).", "FET or bipolar transistors may be "personalized"", "selectively by varying the gate thickness (for FET devices), or the metalizing mask (for both FET and bipolar).", "The logic design principle is based upon expressing desired primitive logic functions as sums of products.", "The structure of the universal logic module relies upon its logic capability to perform higher levels of functions by sequential autonomous operation.", "The design procedure requires the mapping of the primitive functions into the array row cross-points with feedback from the OR-array providing sequential control of selection of those primitives.", "This requires a control field (column) associated with the "addressing"", "of each primitive function.", "If necessary to define control fields that select combinations of primitives simultaneously this can be achieved by using "dont-care"", "translational states in the AND array positions associated with addressing of such primitives.", "Selection of sequences is based upon provision of control field(s) which uniquely identify the sequence as well as individual sequence stages.", "Conclusion From the foregoing description it may now be appreciated that the described module provides the basis for providing families of identically dimensioned and identically organized array logic modules having autonomous operation control capability and providing a wide variety of different operations, within limits imposed by the dimensions chosen for the logic and storage array and the predetermined inter-array internal connections.", "Array dimensions are subject to selection, for a given family or line of modules, as a function of the available technology for large scale integration and the range or repertoire of useful functions contemplated for the complete line.", "While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention." ]
BACKGROUND OF THE INVENTION This invention relates in general to turbomachines and is specifically directed to an arrangement for supporting an annular diaphragm half within a turbomachine. Turbomachines generally comprise stationary and rotating parts defining a flow path for fluid through the turbine. Turbomachines also include an outer fluid tight casing called an outer shell from which a number of stationary parts generally depend radially inwardly toward a rotor surface. One such part is a diaphragm and each turbomachine may have a number of diaphragms spaced axially along the length of the turbomachine. A turbomachine casing may be split along a so-called horizontal joint so that the turbine shell comprises an upper half and a lower half. In building a turbomachine, certain stationary parts are mounted in the lower half shell whereas other stationary parts are mounted in the upper half shell while the two mating components are kept apart. The two halves are then assembled along a horizontal joint after the rotor has been mounted in the lower half. Diaphragms may likewise be split along a horizontal joint and comprise upper and lower diaphragm halves. The diaphragm halves are each mounted in their respective casing parts. It is necessary to vertically align the diaphragm half with the rotor and its respective casing part. The present invention provides a relatively simple arrangement of parts for adjustably supporting an annular diaphragm in its respective casing part. OBJECTS OF THE INVENTION It is one object of the present invention to provide an improved diaphragm support arrangement in a turbomachine casing. It is another object of the present invention to provide an improved diaphragm support arrangement which is vertically adjustable within the turbine casing. Other objects and advantages will become apparent from the following detailed description of the invention and the novel features will be particularly pointed out hereinafter in the claims. BRIEF DESCRIPTION OF THE INVENTION The invention is a support arrangement whereby a diaphragm half can be adjustably mounted into a casing half. The mounting points are at the horizontal joint on each side of the turbine casing. A pair of support lugs are radially inserted into the diaphragm half one on each side of the diaphragm vertical centerline. The support lugs are unique in that they are each formed with a bifurcated head. An adjusting screw is inserted into the turbine shell in a substantially vertical direction on each side of the turbine casing. The adjusting screw is uniquely formed so as to engage the bifurcated head of its respective support lug whereby the diaphragm may be adjusted as the adjusting screw is leveled. After a satisfactory diaphragm position has been attained the assembled components can be locked together by means of a locking tab on the adjusting screw. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view of a support arrangement for a diaphragm within a turbomachine casing lower half according to the prior art. FIG. 2 is an elevation view of a support arrangement for a diaphragm within a turbomachine casing upper half according to the prior art. FIG. 3 is an elevation view, similar to FIG. 1, which shows a diaphragm support arrangement according to the present invention which may be used for both upper and lower diaphragm supports. FIG. 4 is a plan view of the present invention. FIG. 5 is an elevation view of the adjusting screw according to the present invention. FIG. 6 is an elevation view of the support lug according to the present invention. DETAILED DESCRIPTION OF THE INVENTION A turbomachine is any machine comprising a fluid tight casing into which there are mounted stationary components and a rotor and wherein the fluid passes through the casing and either is compressed or expanded. The stationary components and the rotor are interacted in a known manner so as to define a fluid flow path. It is also familiar to those of ordinary skill in the art that the most advantageous method for constructing a turbomachine is to build the outer shell in two halves which will thereafter be assembled along a horizontal joint. The stationary components are each mounted in their respective turbine casing halves and then the rotor is mounted in the lower casing half after which the two halves are joined and bolted. This general construction is well known and needs no further description. FIG. 1 shows a prior art arrangement for assembling a lower half stationary part to a casing shell. FIG. 1 shows a section of the lower turbomachine casing 11 and a section of an annular diaphragm 13 which is also split along a horizontal joint and therefore only the lower half is shown. It should also be kept in mind that the support arrangement shown is only one half of the total support arrangement with an identical arrangement being placed on the opposite side of the turbomachine shell. Hence, at least two support joints are involved with each diaphragm half. The support arrangement for each side comprises a generally horizontal support lug 15 and a generally vertical adjusting screw 17. The adjusting screw is inserted into a bore 19 formed in the head of the support lug in order to vertically adjust the position of the diaphragm. The adjusting screw merely bears against the turbomachine casing at surface 21. One shortcoming of the FIG. 1 embodiment is that it is not suitable for attaching upper diaphragm halves to upper casings. This is due to the fact that adjusting screw 17 is not a holding screw in that it does not retain the diaphragm in the turbomachine casing. In following the assembly procedure of a turbine, the upper casing half is inverted to be assembled to the lower casing half and if that were done to the FIG. 1 representation, the diaphragm would simply fall out of the casing as it was inverted. Another shortcoming of the FIG. 1 embodiment is that thermal expansion causes the adjustment screw 17 to slide against surface 21 causing wear on the casing. FIG. 2 shows an upper casing half 31 and a section of an upper diaphragm section 33. The orientation shown is prior to assembly to the lower casing half and hence prior to the inverting of the upper casing. A support lug 35 is an "L" shaped piece which supports the diaphragm 33 and forms a base for an adjusting screw 37. The support lug further includes a bore 39 into which a holding bolt 40 is inserted. The holding bolt then ties the diaphragm support arrangement to the casing so that when the upper casing half is inverted for assembly the upper diaphragm half will not be displaced. Note that radial expansion will still cause adjusting screw 37 to slide on the bearing surface 41, which occurs this time on the support lug. The separate aforesaid disadvantages are obviated by the present invention which also requires fewer parts and is universal to both the upper and lower casing parts. Further, another disadvantage to the prior art which has now been obviated is described as follows. In the prior art when the embodiments of FIGS. 1 and 2 where used together sometimes during disassembly the upper and lower diaphragms would be locked together. Consequently, as the upper casing half was removed for disassembly, the lower diaphragm half would be drawn upwardly with the upper casing creating the possibility of damage to the rotor and/or the diaphragm. FIGS. 3 and 4 are assembly drawings showing one support point in a turbine casing. It should be understood that the support arrangement will be used to support a semiannular diaphragm section in each side of the lower turbomachine casing and likewise be able to support the annular diaphragm on each side of the upper turbomachine casing including when the turbomachine casing must be overturned as to be mounted on the lower turbomachine casing. One advantage immediately apparent in the present invention is that only two pieces are required rather than three pieces to complete the assembly. The "L" shaped lug has been omitted and moreover the cut-out portion in the diaphragm has also been obviated. A further advantage is that the present invention will be universal to both the upper and lower casing halves. FIG. 3 is an elevation view of a portion of a turbomachine casing half and a portion of the diaphragm is mounted in the turbomachine casing half. FIG. 4 is a plan view of the same assembly. Referring to FIGS. 3 and 4, a diaphragm half 53 is to be mounted to a portion of a turbomachine casing 51. This is accomplished by using a horizontally mounted support lug 55 which is threaded into the diaphragm at hole 56. Again, it is understood that only one mounting point is shown, whereas the turbomachine would include two oppositely located mounting points in the lower casing half and two oppositely located mounting points in the upper casing half. An adjustment screw 57 is vertically mounted into the turbine casing in a threaded hole 59. The adjusting screw 57 is vertically adjustable. Referring to FIGS. 5 and 6, FIG. 5 shows the adjusting screw whereas FIG. 6 shows the support lug. The adjusting screw 57 includes a threaded base 62 which is threaded into the turbine casing. This allows a positive retention of the diaphragm within the turbine casing. The adjusting screw further includes an enlarged platform bearing surface 64, a reduced section 66 and a cap section 68. The support lug 55 is formed with a threaded section 72 and a bifurcated head 78. The adjusting screw 57 and the support lug 55 are arranged during the assembly procedure so that the bifurcated head 78 is supported on the enlarged bearing platform 64 of the adjusting screw and further so that the bifurcated head 78 engages the reduced section 66 of the adjusting screw. In this manner, as the adjusting screw is moved vertically the support lug will follow the movement of the adjusting screw as well as the diaphragm to which the support lug is attached. The horizontal clearances between the adjusting screw and the support lug are such as to allow for radial expansion whereas the bifurcated head permits limited radial movement. As shown in FIGS. 3 and 4, the cap portion 68 of the adjusting screw is formed in sections 69 which are bendable so as to engage the bifurcated head of the support lug whereby a locking arrangement is achieved between the adjusting screw and the support lug. A spacer 81 may be employed between the enlarged bearing platform 64 and the turbomachine shell 51 so as to limit the deflection of the diaphragm in the environment in which the present invention is employed. Thus the present invention provides numerous improvements in a diaphragm support arrangement in a turbomachine casing. The construction reduces the number of overall parts while providing a universal mounting for both the upper and lower diaphragms. Moreover, thermal expansion is accommodated by the use of a bifurcated head on the support lug. The locking tab 69 on the adjustment screw provides positive locking of the adjustment screw whereas the retention of the adjustment screw in the turbomachine casing provides for a means to retain the diaphragm in the turbomachine casing. Further the combination of the bifurcated head on the support lug and the dumbbell shaped adjusting screw provides for positive retention of the diaphragm in the casing, while permitting thermal expansion and providing an improved sliding bearing surface. While there has been shown what is considered to be the preferred embodiment of the invention, it is, of course, understood that various other modifications may be made therein by those skilled in the art. It is intended to cover, in the appended claims, all such modifications which fall within the true spirit and scope of the invention.
A support arrangement is disclosed for supporting an annular diaphragm in a turbine casing. The support arrangement allows the diaphragm to be vertically aligned with respect to the turbine casing and rotor and comprises in its most basic form the combination of a horizontally mounted bifurcated lug and a vertically mounted dumbbell shaped adjusting screw.
Identify and summarize the most critical technical features from the given patent document.
[ "BACKGROUND OF THE INVENTION This invention relates in general to turbomachines and is specifically directed to an arrangement for supporting an annular diaphragm half within a turbomachine.", "Turbomachines generally comprise stationary and rotating parts defining a flow path for fluid through the turbine.", "Turbomachines also include an outer fluid tight casing called an outer shell from which a number of stationary parts generally depend radially inwardly toward a rotor surface.", "One such part is a diaphragm and each turbomachine may have a number of diaphragms spaced axially along the length of the turbomachine.", "A turbomachine casing may be split along a so-called horizontal joint so that the turbine shell comprises an upper half and a lower half.", "In building a turbomachine, certain stationary parts are mounted in the lower half shell whereas other stationary parts are mounted in the upper half shell while the two mating components are kept apart.", "The two halves are then assembled along a horizontal joint after the rotor has been mounted in the lower half.", "Diaphragms may likewise be split along a horizontal joint and comprise upper and lower diaphragm halves.", "The diaphragm halves are each mounted in their respective casing parts.", "It is necessary to vertically align the diaphragm half with the rotor and its respective casing part.", "The present invention provides a relatively simple arrangement of parts for adjustably supporting an annular diaphragm in its respective casing part.", "OBJECTS OF THE INVENTION It is one object of the present invention to provide an improved diaphragm support arrangement in a turbomachine casing.", "It is another object of the present invention to provide an improved diaphragm support arrangement which is vertically adjustable within the turbine casing.", "Other objects and advantages will become apparent from the following detailed description of the invention and the novel features will be particularly pointed out hereinafter in the claims.", "BRIEF DESCRIPTION OF THE INVENTION The invention is a support arrangement whereby a diaphragm half can be adjustably mounted into a casing half.", "The mounting points are at the horizontal joint on each side of the turbine casing.", "A pair of support lugs are radially inserted into the diaphragm half one on each side of the diaphragm vertical centerline.", "The support lugs are unique in that they are each formed with a bifurcated head.", "An adjusting screw is inserted into the turbine shell in a substantially vertical direction on each side of the turbine casing.", "The adjusting screw is uniquely formed so as to engage the bifurcated head of its respective support lug whereby the diaphragm may be adjusted as the adjusting screw is leveled.", "After a satisfactory diaphragm position has been attained the assembled components can be locked together by means of a locking tab on the adjusting screw.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view of a support arrangement for a diaphragm within a turbomachine casing lower half according to the prior art.", "FIG. 2 is an elevation view of a support arrangement for a diaphragm within a turbomachine casing upper half according to the prior art.", "FIG. 3 is an elevation view, similar to FIG. 1, which shows a diaphragm support arrangement according to the present invention which may be used for both upper and lower diaphragm supports.", "FIG. 4 is a plan view of the present invention.", "FIG. 5 is an elevation view of the adjusting screw according to the present invention.", "FIG. 6 is an elevation view of the support lug according to the present invention.", "DETAILED DESCRIPTION OF THE INVENTION A turbomachine is any machine comprising a fluid tight casing into which there are mounted stationary components and a rotor and wherein the fluid passes through the casing and either is compressed or expanded.", "The stationary components and the rotor are interacted in a known manner so as to define a fluid flow path.", "It is also familiar to those of ordinary skill in the art that the most advantageous method for constructing a turbomachine is to build the outer shell in two halves which will thereafter be assembled along a horizontal joint.", "The stationary components are each mounted in their respective turbine casing halves and then the rotor is mounted in the lower casing half after which the two halves are joined and bolted.", "This general construction is well known and needs no further description.", "FIG. 1 shows a prior art arrangement for assembling a lower half stationary part to a casing shell.", "FIG. 1 shows a section of the lower turbomachine casing 11 and a section of an annular diaphragm 13 which is also split along a horizontal joint and therefore only the lower half is shown.", "It should also be kept in mind that the support arrangement shown is only one half of the total support arrangement with an identical arrangement being placed on the opposite side of the turbomachine shell.", "Hence, at least two support joints are involved with each diaphragm half.", "The support arrangement for each side comprises a generally horizontal support lug 15 and a generally vertical adjusting screw 17.", "The adjusting screw is inserted into a bore 19 formed in the head of the support lug in order to vertically adjust the position of the diaphragm.", "The adjusting screw merely bears against the turbomachine casing at surface 21.", "One shortcoming of the FIG. 1 embodiment is that it is not suitable for attaching upper diaphragm halves to upper casings.", "This is due to the fact that adjusting screw 17 is not a holding screw in that it does not retain the diaphragm in the turbomachine casing.", "In following the assembly procedure of a turbine, the upper casing half is inverted to be assembled to the lower casing half and if that were done to the FIG. 1 representation, the diaphragm would simply fall out of the casing as it was inverted.", "Another shortcoming of the FIG. 1 embodiment is that thermal expansion causes the adjustment screw 17 to slide against surface 21 causing wear on the casing.", "FIG. 2 shows an upper casing half 31 and a section of an upper diaphragm section 33.", "The orientation shown is prior to assembly to the lower casing half and hence prior to the inverting of the upper casing.", "A support lug 35 is an "L"", "shaped piece which supports the diaphragm 33 and forms a base for an adjusting screw 37.", "The support lug further includes a bore 39 into which a holding bolt 40 is inserted.", "The holding bolt then ties the diaphragm support arrangement to the casing so that when the upper casing half is inverted for assembly the upper diaphragm half will not be displaced.", "Note that radial expansion will still cause adjusting screw 37 to slide on the bearing surface 41, which occurs this time on the support lug.", "The separate aforesaid disadvantages are obviated by the present invention which also requires fewer parts and is universal to both the upper and lower casing parts.", "Further, another disadvantage to the prior art which has now been obviated is described as follows.", "In the prior art when the embodiments of FIGS. 1 and 2 where used together sometimes during disassembly the upper and lower diaphragms would be locked together.", "Consequently, as the upper casing half was removed for disassembly, the lower diaphragm half would be drawn upwardly with the upper casing creating the possibility of damage to the rotor and/or the diaphragm.", "FIGS. 3 and 4 are assembly drawings showing one support point in a turbine casing.", "It should be understood that the support arrangement will be used to support a semiannular diaphragm section in each side of the lower turbomachine casing and likewise be able to support the annular diaphragm on each side of the upper turbomachine casing including when the turbomachine casing must be overturned as to be mounted on the lower turbomachine casing.", "One advantage immediately apparent in the present invention is that only two pieces are required rather than three pieces to complete the assembly.", "The "L"", "shaped lug has been omitted and moreover the cut-out portion in the diaphragm has also been obviated.", "A further advantage is that the present invention will be universal to both the upper and lower casing halves.", "FIG. 3 is an elevation view of a portion of a turbomachine casing half and a portion of the diaphragm is mounted in the turbomachine casing half.", "FIG. 4 is a plan view of the same assembly.", "Referring to FIGS. 3 and 4, a diaphragm half 53 is to be mounted to a portion of a turbomachine casing 51.", "This is accomplished by using a horizontally mounted support lug 55 which is threaded into the diaphragm at hole 56.", "Again, it is understood that only one mounting point is shown, whereas the turbomachine would include two oppositely located mounting points in the lower casing half and two oppositely located mounting points in the upper casing half.", "An adjustment screw 57 is vertically mounted into the turbine casing in a threaded hole 59.", "The adjusting screw 57 is vertically adjustable.", "Referring to FIGS. 5 and 6, FIG. 5 shows the adjusting screw whereas FIG. 6 shows the support lug.", "The adjusting screw 57 includes a threaded base 62 which is threaded into the turbine casing.", "This allows a positive retention of the diaphragm within the turbine casing.", "The adjusting screw further includes an enlarged platform bearing surface 64, a reduced section 66 and a cap section 68.", "The support lug 55 is formed with a threaded section 72 and a bifurcated head 78.", "The adjusting screw 57 and the support lug 55 are arranged during the assembly procedure so that the bifurcated head 78 is supported on the enlarged bearing platform 64 of the adjusting screw and further so that the bifurcated head 78 engages the reduced section 66 of the adjusting screw.", "In this manner, as the adjusting screw is moved vertically the support lug will follow the movement of the adjusting screw as well as the diaphragm to which the support lug is attached.", "The horizontal clearances between the adjusting screw and the support lug are such as to allow for radial expansion whereas the bifurcated head permits limited radial movement.", "As shown in FIGS. 3 and 4, the cap portion 68 of the adjusting screw is formed in sections 69 which are bendable so as to engage the bifurcated head of the support lug whereby a locking arrangement is achieved between the adjusting screw and the support lug.", "A spacer 81 may be employed between the enlarged bearing platform 64 and the turbomachine shell 51 so as to limit the deflection of the diaphragm in the environment in which the present invention is employed.", "Thus the present invention provides numerous improvements in a diaphragm support arrangement in a turbomachine casing.", "The construction reduces the number of overall parts while providing a universal mounting for both the upper and lower diaphragms.", "Moreover, thermal expansion is accommodated by the use of a bifurcated head on the support lug.", "The locking tab 69 on the adjustment screw provides positive locking of the adjustment screw whereas the retention of the adjustment screw in the turbomachine casing provides for a means to retain the diaphragm in the turbomachine casing.", "Further the combination of the bifurcated head on the support lug and the dumbbell shaped adjusting screw provides for positive retention of the diaphragm in the casing, while permitting thermal expansion and providing an improved sliding bearing surface.", "While there has been shown what is considered to be the preferred embodiment of the invention, it is, of course, understood that various other modifications may be made therein by those skilled in the art.", "It is intended to cover, in the appended claims, all such modifications which fall within the true spirit and scope of the invention." ]
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a vacuum cleaner construction which may be converted readily into different configurations each suitable for a specifically different type of vacuum cleaning operation. More particularly, this invention provides for the conversion of vacuum cleaning apparatus selectively into an arrangement suitable for floor supported vacuuming; hand carried vacuum cleaning operation; or cannister type vacuum cleaning via a flexible hose attachment. 2. Description of the Prior Art Known vacuum cleaners having handles selectively positionable in either an extended position for floor supported vacuum cleaning operation or retracted position for hand carried cleaning disclosed in U.S. Pat. Nos. 1,558,006 of Fisker, Oct. 20, 1925, and 3,758,914 of Nupp et al, Sept. 18, 1973, are awkward in use in both modes of operation. In floor supported mode, the handles are not pivoted to the nozzle carrying head of the cleaner so that manipulation under furniture is difficult and the cleaner does not have a stable upright position in which it can be left unattended by the operator. In the hand carried mode, these prior art devices are ungainly in length in order to accommodate the handle length necessary for floor supported use. The U.S. Pat. No. 3,203,7087 of Anderson, Aug. 31, 1965, discloses an appliance handle which is pivoted to the appliance head during floor supported operation of the appliance; but, in the hand carried mode if applied to a vacuum cleaner, would dispose the nozzle and brush at an awkward right angle to the handle thus drastically reducing the effectiveness of hand carried vacuum cleaning operation. SUMMARY OF THE INVENTION It is an object of this invention to provide a vacuum cleaner construction which can be converted quickly and easily into forms suitable for floor supported vacuum cleaning operation, hand carried vacuum cleaning operation, or cannister type off-the-floor cleaning operation via a flexible hose attachment. It is a further object of this invention to provide a vacuum cleaner construction which, in each of the possible converted modes of operation, supplies features to the vacuum cleaner conducive to convenient usages of the vacuum cleaner; i.e., a handle freely pivoted with respect to the nozzle head of the cleaner in floor supported mode for access beneath furniture or the like, and stability in an upright position so that the cleaner may be parked unattended by an operator; compact rigidly interlocked arrangement of vacuum cleaner handle and nozzle head in the hand carried mode; and horizontal low-center of gravity of vacuum cleaner handle, body, and nozzle head in cannister type off-the-floor cleaning mode via a flexible hose attachment to minimize the tendency of the cleaner to overturn when drawn along by pull on the attached hose. DESCRIPTION OF THE DRAWINGS The above and additional objects and advantages of this invention will be apparent from the following description taken in conjunction with the accompanying drawings of a preferred embodiment in which: FIG. 1 is a front perspective view of a vacuum cleaner having a handle in accordance with this invention applied thereto and arranged in a position suitable for floor supported operation of the vacuum cleaner; FIG. 2 is a front perspective view of the vacuum cleaner of FIG. 1 showing the handle arranged in a position suitable for hand carried vacuum cleaner operation; FIG. 3 is an enlarged elevational view of the handle of this invention with the parts shown interlocked in the extended position suitable for floor supported vacuum cleaner operation and with portions of the handle segments broken away and illustrated in cross section; FIG. 4 is an enlarged elevational view of the handle similar to that of FIG. 3, but with the interlocks between parts released and the parts shifted to extreme extended relation suitable for accommodating relative rotation; FIG. 5 is an enlarged elevational view of the handle similar to that of FIG. 3, but with the parts shown interlocked in retracted position suitable for hand carried vacuum cleaner operation; and FIG. 6 is an enlarged cross sectional view taken substantially along line 6--6 of FIG. 2, and including a flexible hose fitting accommodated in the head portion of the cleaner. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring particularly to FIG. 1 of the drawings, this invention is illustrated as applied to a vacuum cleaner indicated generally at 11 and comprising a housing including a head portion 12 pivotally connected to a body portion 13. Wheels 14 may be rotationally supported on or adjacent the pivotal connection between the head and body portions. A motor blower 15 is arranged in the head portion together with a nozzle 16 which may be fitted with a driven brush 17. A flexible tube 18 extends from the motor blower 15 in the head portion 12 along a trough 19 formed in the rear of the body portion 13 and provides a conduit to an exhaust fitting 20 providing a terminus to the air conduit from the vacuum cleaner nozzle 16. The exhaust fitting 20 is preferably fitted with a flexible gasket 22. Retaining fingers 23 extending from the rear of the vacuum cleaner body portion 13 provide storage for coils of the power cord 24 for the motor blower. The body portion 13 of the vacuum cleaner housing is adapted to be closed by a cover 30 having the form of a shallow tray. The tray-like cover 30 is provided with a bent wire dirt bag retainer 32 shaped so as to embrace and locate a collar portion 33 of a disposable dirt collecting bag 34 in registry with the exhaust fitting 20 in effective position to separate and collect dirt from air delivered into the bag from the conduit. The free extremity of the cleaner body portion 13 and the cover 30 are formed with aligned recesses 35 and 36, respectively, adapted to accommodate means for supporting a handle indicated generally at 50 on the vacuum cleaner. Preferably, the handle is supported on the cleaner body by a U-shaped bracket 41 which, as best shown in FIGS. 3 and 5, has a base 42 secured to the cleaner body by any suitable means, such as a staking 43, or use of a rivet or other fastening device. The bracket 41 is formed with a pair of bracket arms 44 in which bearing projections 47 formed on the handle 50 are journaled. The handle 50 may be pivoted relatively to the vacuum cleaner housing selectively into either of two positions, each suitable for a different mode of vacuum cleaner operation. FIGS. 1 and 3 illustrate the extended position of the handle relatively to the cleaner housing suiting the cleaner for upright floor supported vacuum cleaning operation, while FIGS. 2, 5 and 6 illustrate the retracted position of the handle suitable for hand carried vacuum cleaning operation. The preferred construction of the handle 50 and the means for accommodating the handle in two different positions without appreciable limitation on the size and configuration of the vacuum cleaner housing will now be described. Preferably, the handle 50 is formed with two telescopically and rotationally interrelated parts 51 and 52, part 51 being that formed with the bearing projections 47. The part 52, which is formed at one extremity with a hand grip 53, is slidable lengthwise within the handle part 51 and at the extremity opposite the hand grip carries a latch button 54 loaded by a spring 45, which latch button is engageable with a latch aperture 55 near the free extremity of the handle portion 51 to lock the handle parts in extended position, or with a latch aperture 56 near the pivoted extremity of the handle portion 51 to lock the handle parts in retracted position depending upon the relative rotational position of the handle parts. In the retracted postion of the handle parts, as shown in FIG. 5, a projection 57 on handle part 52 seats in a socket 58 in the cover 30 to constrain the handle in position for supporting the cleaner in a hand carried vacuum cleaning operation. A major portion of both handle parts 51 and 52 are formed with rectangular configuration as shown in the perspective view of FIG. 2 and telescopically related. The extremity of the handle part 52 opposite the hand grip 53 is formed with a cylindrical cross sectional shape 62 to accommodate rotational movement of the handle parts when the latch button 54 is depressed into the aperture 55. When so depressed, the latch button 54 may be accommodated in an undercut 46 in the hollow interior 60 to prevent complete separation of the handle parts 51 and 52. FIGS. 1 and 3 illustrate a latch device effective to constrain the handle in the extended position relatively to the cleaner housing rendering the cleaner suitable for upright floor supported vacuum cleaning operation. This latch device comprises a flexible latch element 70 secured inside the handle portion 51 and arranged protruding from the handle, as illustrated in FIGS. 1 and 3, to engage beneath a shoulder 71 on the cleaner body portion 13 to retain the handle in the postion shown in FIGS. 1 and 3. A release button 72 carried by the latch element 70 within the handle portion 51 is accessible to an operator through an aperture 73 in the handle permitting the latch element 70 to be shifted out of engagement beneath the shoulder 71 freeing the handle for pivotal movement out of the extended position. FIG. 5 best illustrates the latch device effective to constrain the handle in the retracted position relatively to the cleaner housing rendering the cleaner suitable for hand carried vacuum cleaning operation in the form illustrated in FIG. 2. As described above, and with particular reference to FIG. 5, when the handle part 52 is rotated 180° from the position relative to the handle part 51 shown in FIGS. 1 and 3 and the handle 50 is rotated about the bearing projections 47 into retracted position adjacent the cleaner housing, the handle part 52, upon telescopic insertion into handle part 51, shifts a projection 57 on handle part 52 into a cover socket 58 substantially simultaneously with the reception of the latch button 55 into the aperture 56 in the handle part 51. To remove any looseness in the interlocking relation between the handle and the cleaner housing, a resilient tab 80 is formed to extend from the handle part 52 adjacent to the projection 57. The tab 80 engages the cover 30 in the interlocked position of the projection within the socket 58 and, in being deflected thereby, the resilient tab 80 imposes a light force between the handle 50 and the cleaner housing to remove any slack therebetween. With reference to FIG. 6, the pivotal connection between the cleaner head portion 12 and body portion 13 is illustrated. Indicated at 90 is an axle stud for one of the cleaner wheels 14, which axle studs are journaled in extensions 91 from the cleaner head portion 12. The studs 90 also extend laterally inward from the extensions 91 and are embraced by the body portion 13 of the cleaner to provide the pivotal connection between the cleaner housing parts 11 and 12. As shown in FIG. 6, the housing parts 11 and 12 are formed with interchanging stop surfaces 92 and 93, respectively, adjacent pivotal connections therebetween. The stop surfaces are adapted to abut defining one extreme limit of the angular range of pivotal movement between the body and head portion of the cleaner housing in which, as shown in FIGS. 2 and 6, the undersides of the head and body portions 11 and 12 are substantially coplanar. As shown in FIGS. 2, 5 and 6, the handle, when shifted into retracted position, brings the hand grip 53 into engagement with a raised abutment projection 100 formed on the upper surface of the head portion 12 of the cleaner. As the handle parts 51 and 52 are shifted telescopically into the retracted position, the hand grip 53 acts as a cam means in engaging the projection and urging the stop surfaces 92 and 93 into engagement. Engagement of the latch button 54 into the aperture 56 of handle part 51 locks the cleaner head and body portions in this extreme position of angular relation shown in FIGS. 2, 5 and 6. As shown in FIG. 2, the head portion 12 of the cleaner housing is formed in the upper surface with an opening into the nozzle 16 which can be closed by a hinged cover plate 111. When the cover plate 111 is swung up, as shown in FIG. 6, the opening is exposed to accommodate an adapter 112 carried by one extremity of a flexible hose 113 to the opposite extremity of which various cleaning implements such as a brush 114 or the like may be carried. The adapter 112 is shaped, as shown in FIG. 6, to block off the nozzle 16 passageway to the motor blower when the adapter is fully inserted into the opening 110 so that air will be drawn by the blower instead of through the flexible hose 113. When the flexible hose 113 is utilized, the cleaner is adapted for use in the mode of a cannister cleaner and particularly adapted for off-the-floor cleaning operations in the course of which the cleaner housing is apt to be drawn along by forces imparted thereto by the flexible hose 113. In the form of the cleaner of this invention, as shown in FIGS. 2 and 6, the compact configuration of cleaner parts and the low silouette provided by the retracted postion of the handle 50 provides a stability to the cleaner housing which resists tipping and overturning to which the cleaner would be prone in the upright mode shown in FIG. 1.
A vacuum cleaner having pivotally interconnected body and nozzle head portions and a handle which is extendable for upright floor cleaning operation or retractable for hand carried or cannister type vacuuming operation, in which the handle in retracted position fixes the cleaner body and nozzle head portions against pivotal movement.
Briefly describe the main invention outlined in the provided context.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention This invention relates to a vacuum cleaner construction which may be converted readily into different configurations each suitable for a specifically different type of vacuum cleaning operation.", "More particularly, this invention provides for the conversion of vacuum cleaning apparatus selectively into an arrangement suitable for floor supported vacuuming;", "hand carried vacuum cleaning operation;", "or cannister type vacuum cleaning via a flexible hose attachment.", "Description of the Prior Art Known vacuum cleaners having handles selectively positionable in either an extended position for floor supported vacuum cleaning operation or retracted position for hand carried cleaning disclosed in U.S. Pat. Nos. 1,558,006 of Fisker, Oct. 20, 1925, and 3,758,914 of Nupp et al, Sept.", "18, 1973, are awkward in use in both modes of operation.", "In floor supported mode, the handles are not pivoted to the nozzle carrying head of the cleaner so that manipulation under furniture is difficult and the cleaner does not have a stable upright position in which it can be left unattended by the operator.", "In the hand carried mode, these prior art devices are ungainly in length in order to accommodate the handle length necessary for floor supported use.", "The U.S. Pat. No. 3,203,7087 of Anderson, Aug. 31, 1965, discloses an appliance handle which is pivoted to the appliance head during floor supported operation of the appliance;", "but, in the hand carried mode if applied to a vacuum cleaner, would dispose the nozzle and brush at an awkward right angle to the handle thus drastically reducing the effectiveness of hand carried vacuum cleaning operation.", "SUMMARY OF THE INVENTION It is an object of this invention to provide a vacuum cleaner construction which can be converted quickly and easily into forms suitable for floor supported vacuum cleaning operation, hand carried vacuum cleaning operation, or cannister type off-the-floor cleaning operation via a flexible hose attachment.", "It is a further object of this invention to provide a vacuum cleaner construction which, in each of the possible converted modes of operation, supplies features to the vacuum cleaner conducive to convenient usages of the vacuum cleaner;", "i.e., a handle freely pivoted with respect to the nozzle head of the cleaner in floor supported mode for access beneath furniture or the like, and stability in an upright position so that the cleaner may be parked unattended by an operator;", "compact rigidly interlocked arrangement of vacuum cleaner handle and nozzle head in the hand carried mode;", "and horizontal low-center of gravity of vacuum cleaner handle, body, and nozzle head in cannister type off-the-floor cleaning mode via a flexible hose attachment to minimize the tendency of the cleaner to overturn when drawn along by pull on the attached hose.", "DESCRIPTION OF THE DRAWINGS The above and additional objects and advantages of this invention will be apparent from the following description taken in conjunction with the accompanying drawings of a preferred embodiment in which: FIG. 1 is a front perspective view of a vacuum cleaner having a handle in accordance with this invention applied thereto and arranged in a position suitable for floor supported operation of the vacuum cleaner;", "FIG. 2 is a front perspective view of the vacuum cleaner of FIG. 1 showing the handle arranged in a position suitable for hand carried vacuum cleaner operation;", "FIG. 3 is an enlarged elevational view of the handle of this invention with the parts shown interlocked in the extended position suitable for floor supported vacuum cleaner operation and with portions of the handle segments broken away and illustrated in cross section;", "FIG. 4 is an enlarged elevational view of the handle similar to that of FIG. 3, but with the interlocks between parts released and the parts shifted to extreme extended relation suitable for accommodating relative rotation;", "FIG. 5 is an enlarged elevational view of the handle similar to that of FIG. 3, but with the parts shown interlocked in retracted position suitable for hand carried vacuum cleaner operation;", "and FIG. 6 is an enlarged cross sectional view taken substantially along line 6--6 of FIG. 2, and including a flexible hose fitting accommodated in the head portion of the cleaner.", "DESCRIPTION OF THE PREFERRED EMBODIMENT Referring particularly to FIG. 1 of the drawings, this invention is illustrated as applied to a vacuum cleaner indicated generally at 11 and comprising a housing including a head portion 12 pivotally connected to a body portion 13.", "Wheels 14 may be rotationally supported on or adjacent the pivotal connection between the head and body portions.", "A motor blower 15 is arranged in the head portion together with a nozzle 16 which may be fitted with a driven brush 17.", "A flexible tube 18 extends from the motor blower 15 in the head portion 12 along a trough 19 formed in the rear of the body portion 13 and provides a conduit to an exhaust fitting 20 providing a terminus to the air conduit from the vacuum cleaner nozzle 16.", "The exhaust fitting 20 is preferably fitted with a flexible gasket 22.", "Retaining fingers 23 extending from the rear of the vacuum cleaner body portion 13 provide storage for coils of the power cord 24 for the motor blower.", "The body portion 13 of the vacuum cleaner housing is adapted to be closed by a cover 30 having the form of a shallow tray.", "The tray-like cover 30 is provided with a bent wire dirt bag retainer 32 shaped so as to embrace and locate a collar portion 33 of a disposable dirt collecting bag 34 in registry with the exhaust fitting 20 in effective position to separate and collect dirt from air delivered into the bag from the conduit.", "The free extremity of the cleaner body portion 13 and the cover 30 are formed with aligned recesses 35 and 36, respectively, adapted to accommodate means for supporting a handle indicated generally at 50 on the vacuum cleaner.", "Preferably, the handle is supported on the cleaner body by a U-shaped bracket 41 which, as best shown in FIGS. 3 and 5, has a base 42 secured to the cleaner body by any suitable means, such as a staking 43, or use of a rivet or other fastening device.", "The bracket 41 is formed with a pair of bracket arms 44 in which bearing projections 47 formed on the handle 50 are journaled.", "The handle 50 may be pivoted relatively to the vacuum cleaner housing selectively into either of two positions, each suitable for a different mode of vacuum cleaner operation.", "FIGS. 1 and 3 illustrate the extended position of the handle relatively to the cleaner housing suiting the cleaner for upright floor supported vacuum cleaning operation, while FIGS. 2, 5 and 6 illustrate the retracted position of the handle suitable for hand carried vacuum cleaning operation.", "The preferred construction of the handle 50 and the means for accommodating the handle in two different positions without appreciable limitation on the size and configuration of the vacuum cleaner housing will now be described.", "Preferably, the handle 50 is formed with two telescopically and rotationally interrelated parts 51 and 52, part 51 being that formed with the bearing projections 47.", "The part 52, which is formed at one extremity with a hand grip 53, is slidable lengthwise within the handle part 51 and at the extremity opposite the hand grip carries a latch button 54 loaded by a spring 45, which latch button is engageable with a latch aperture 55 near the free extremity of the handle portion 51 to lock the handle parts in extended position, or with a latch aperture 56 near the pivoted extremity of the handle portion 51 to lock the handle parts in retracted position depending upon the relative rotational position of the handle parts.", "In the retracted postion of the handle parts, as shown in FIG. 5, a projection 57 on handle part 52 seats in a socket 58 in the cover 30 to constrain the handle in position for supporting the cleaner in a hand carried vacuum cleaning operation.", "A major portion of both handle parts 51 and 52 are formed with rectangular configuration as shown in the perspective view of FIG. 2 and telescopically related.", "The extremity of the handle part 52 opposite the hand grip 53 is formed with a cylindrical cross sectional shape 62 to accommodate rotational movement of the handle parts when the latch button 54 is depressed into the aperture 55.", "When so depressed, the latch button 54 may be accommodated in an undercut 46 in the hollow interior 60 to prevent complete separation of the handle parts 51 and 52.", "FIGS. 1 and 3 illustrate a latch device effective to constrain the handle in the extended position relatively to the cleaner housing rendering the cleaner suitable for upright floor supported vacuum cleaning operation.", "This latch device comprises a flexible latch element 70 secured inside the handle portion 51 and arranged protruding from the handle, as illustrated in FIGS. 1 and 3, to engage beneath a shoulder 71 on the cleaner body portion 13 to retain the handle in the postion shown in FIGS. 1 and 3.", "A release button 72 carried by the latch element 70 within the handle portion 51 is accessible to an operator through an aperture 73 in the handle permitting the latch element 70 to be shifted out of engagement beneath the shoulder 71 freeing the handle for pivotal movement out of the extended position.", "FIG. 5 best illustrates the latch device effective to constrain the handle in the retracted position relatively to the cleaner housing rendering the cleaner suitable for hand carried vacuum cleaning operation in the form illustrated in FIG. 2. As described above, and with particular reference to FIG. 5, when the handle part 52 is rotated 180° from the position relative to the handle part 51 shown in FIGS. 1 and 3 and the handle 50 is rotated about the bearing projections 47 into retracted position adjacent the cleaner housing, the handle part 52, upon telescopic insertion into handle part 51, shifts a projection 57 on handle part 52 into a cover socket 58 substantially simultaneously with the reception of the latch button 55 into the aperture 56 in the handle part 51.", "To remove any looseness in the interlocking relation between the handle and the cleaner housing, a resilient tab 80 is formed to extend from the handle part 52 adjacent to the projection 57.", "The tab 80 engages the cover 30 in the interlocked position of the projection within the socket 58 and, in being deflected thereby, the resilient tab 80 imposes a light force between the handle 50 and the cleaner housing to remove any slack therebetween.", "With reference to FIG. 6, the pivotal connection between the cleaner head portion 12 and body portion 13 is illustrated.", "Indicated at 90 is an axle stud for one of the cleaner wheels 14, which axle studs are journaled in extensions 91 from the cleaner head portion 12.", "The studs 90 also extend laterally inward from the extensions 91 and are embraced by the body portion 13 of the cleaner to provide the pivotal connection between the cleaner housing parts 11 and 12.", "As shown in FIG. 6, the housing parts 11 and 12 are formed with interchanging stop surfaces 92 and 93, respectively, adjacent pivotal connections therebetween.", "The stop surfaces are adapted to abut defining one extreme limit of the angular range of pivotal movement between the body and head portion of the cleaner housing in which, as shown in FIGS. 2 and 6, the undersides of the head and body portions 11 and 12 are substantially coplanar.", "As shown in FIGS. 2, 5 and 6, the handle, when shifted into retracted position, brings the hand grip 53 into engagement with a raised abutment projection 100 formed on the upper surface of the head portion 12 of the cleaner.", "As the handle parts 51 and 52 are shifted telescopically into the retracted position, the hand grip 53 acts as a cam means in engaging the projection and urging the stop surfaces 92 and 93 into engagement.", "Engagement of the latch button 54 into the aperture 56 of handle part 51 locks the cleaner head and body portions in this extreme position of angular relation shown in FIGS. 2, 5 and 6.", "As shown in FIG. 2, the head portion 12 of the cleaner housing is formed in the upper surface with an opening into the nozzle 16 which can be closed by a hinged cover plate 111.", "When the cover plate 111 is swung up, as shown in FIG. 6, the opening is exposed to accommodate an adapter 112 carried by one extremity of a flexible hose 113 to the opposite extremity of which various cleaning implements such as a brush 114 or the like may be carried.", "The adapter 112 is shaped, as shown in FIG. 6, to block off the nozzle 16 passageway to the motor blower when the adapter is fully inserted into the opening 110 so that air will be drawn by the blower instead of through the flexible hose 113.", "When the flexible hose 113 is utilized, the cleaner is adapted for use in the mode of a cannister cleaner and particularly adapted for off-the-floor cleaning operations in the course of which the cleaner housing is apt to be drawn along by forces imparted thereto by the flexible hose 113.", "In the form of the cleaner of this invention, as shown in FIGS. 2 and 6, the compact configuration of cleaner parts and the low silouette provided by the retracted postion of the handle 50 provides a stability to the cleaner housing which resists tipping and overturning to which the cleaner would be prone in the upright mode shown in FIG. 1." ]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for removing sulfate ions from extracted phosphoric acid. 2. Description of the Prior Art In the past, it has been known that wet process phosphoric acid which is produced by sulfuric acid decomposition of phosphate rock, can be extracted by an organic solvent which dissolves phosphoric acid and has low solubility to water. Such solvents include various alcohols, ketones, ethers, phosphoric acid esters, amines, and the like. After this treatment, the phosphoric acid is extracted by water from the extracted solution of phosphoric acid (hereinafter referred to as the "extraction method"). In this specification, phosphoric acid prepared by purifying the crude phosphoric acid from the wet process (including a pretreated acid) by the extraction method (including a concentration step) will be referred to as the "extracted phosphoric acid". The phosphoric acid produced by the wet process contains various metallic ion impurities derived from a phosphate rock and sulfate ions derived from sulfuric acid. Using the extraction method, the metallic ion impurities can be effectively removed. However, the sulfate ions are not satisfactorily removed and a large amount of sulfate ions still remain in the extracted phosphoric acid. The phosphoric acid used in industrial products, medicines and foods must be a pure phosphoric acid having substantially no sulfate ions, such as one having less than 30 wt. ppm as SO 4 as in the Japanese Industrial Standard. In order to decrease sulfate ions sufficiently for use of the phosphoric acid in the industrial applications, it is necessary to remove sulfate ions from the wet process phosphoric acid or from the extracted phosphoric acid. It has been known to remove sulfate ions as calcium sulfate from a wet process phosphoric acid by adding a calcium compound such as phosphate rock, calcium hydroxide or calcium carbonate. However, calcium sulfate has a relatively high solubility. Accordingly, even though a large excess of the calcium compound is used, sulfate ions remain present in a concentration in the range of 1000-2000 wt. ppm as SO 4 . It is difficult to lower the concentration of the sulfate ions. Even when the desulfated wet process phosphoric acid is further purified by extraction, sulfate ions in a concentration of at least 500 wt. ppm as SO 4 remain in the extracted phosphoric acid. It has also been known to remove sulfate ions as barium sulfate and thereby lower the concentration by using a barium compound. However, it is not preferred to use that method on the wet process phosphoric acid because of the following reasons. a. The sulfate ion content is higher than that of the extracted phosphoric acid whereby the consumption of the expensive barium compound is high. b. Hydrofluorosilicic acid is generally present whereby the barium compound is consumed for the formation of crystals of barium fluorosilicate. c. The concentrations of the sulfate ion and hydrofluorosilicic acid fluctuates depending upon the fluctuations in the composition of the phosphate rock and the operating conditions are critical whereby the phosphoric acid may be contaminated by barium ions because of an inadvertant excess addition of the barium compound. d. Hydrofluoric acid is also present. Accordingly, the selection of a suitable material for the filter used for separating the barium sulfate is restricted. Moreover, it is difficult to use stainless steel. e. The crystals of barium sulfate are fine and smaller than those of the extracted phosphoric acid. This may be caused by the presence of organic materials and metallic impurities. Moreover, the viscosity of the slurry is high even though the concentration of phosphoric acid is low. Accordingly, the separation of barium sulfate is difficult. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a process for removing sulfate ions from extracted phosphoric acid wherein the operation for precipitating the sulfate ions is easy and stable and the reaction time and the aging time are shortened so that continuous operation of the series of steps is feasible with a simplification and miniaturization of the apparatus required. It is another object of the present invention to provide a process for substantially removing sulfate ions from extracted phosphoric acid to the degree required for the use of the phosphoric acid in industrial products, medicines and foods, without the formation of super-fine crystals and without formation of turbidity during storage or in the various uses, whereby a shorter aging time is required for prevention of turbidity after the filtering operation in a continuous system. These and other objects of this invention as will hereinafter become clear have been attained by providing a process for substantially removing sulfate ions from extracted phosphoric acid which comprises adding a barium compound to the extracted phosphoric acid, then adding active carbon to the resulting slurry and separating the solid components from the slurry. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The inventors have made several studies of processes for substantially removing sulfate ions from extracted phosphoric acid as barium sulfate. As a result, it has been found that super-fine crystals of barium sulfate which are very much smaller than the size of fine crystals are formed by the reaction of sulfate ions with barium ions. Moreover, turbidity is formed by long storage after the separation of the barium sulfate, or in the preparation of condensed phosphoric acids. It has also been found that these phenomena do not occur when no barium compound treatment is used. Accordingly, it is clear that the turbidity phenomenon is caused by the barium compound treatment. It has been determined that the phenomena are caused by the dissolved barium ions in the phosphoric acid. It is known that barium sulfate is an insoluble salt. Its solubility product in water is in the range of 8.7 × 10.sup. -11 to 2.8 × 10.sup. -10 , quite insoluble. However, according to measurements, the solubility product of barium sulfate in pure phosphoric acid varies in the range of from 1 × 10 -6 to 2 × 10.sup. -9 depending upon the concentration of its phosphoric acid and the temperature. It is clear that barium sulfate is still sparingly soluble but is relatively more soluble in phosphoric acid than in water. In accordance with these new findings, the present inventors have determined that the formation of super-fine crystals and turbidity can be prevented by controlling the amount of the barium compound added so that the amount of remaining dissolved sulfate ions is at least 5 wt. ppm as SO 4 in the extracted phosphoric acid. However, the extracted phosphoric acid contains dissolved sulfate ions in the range of 500-5000 wt. ppm as SO 4 . Therefore, it is difficult to decrease the SO 4 content from 500-5000 wt. ppm to 5-30 wt. ppm by the single step of addition of the barium compound. The problems encountered involve the accuracy of analysis of SO 4 , the purity of the barium compound, the accuracy of weighing, etc. As a result, there is a high possibility of excess addition of the barium compound. When a plurality of additions of the barium compound are used each followed by a measurement of the sulfate ion concentration in the phosphoric acid, the concentration of the dissolved sulfate can be adjusted into the proper range in relative safety. However, in this technique, super-saturation of barium sulfate is relatively stable whereby it is necessary to age the slurry for a long time. Accordingly, a large size reactor is required and a batch system must be used. The inventors have also found that it is necessary to age the slurry for a long time before the separation of the solid components in order to prevent turbidity in storage even though clear phosphoric acid can be obtained by separating the solid compounds from the slurry resulting from the addition of the barium compound. The present inventors have discovered the above-mentioned problems which were consequently considered in determining a process for removing sulfate ions from extracted phosphoric acid by addition of a barium compound. As a result, it has been found that when a barium compound is added to extracted phosphoric acid to convert a part of the sulfate ions to barium sulfate and to precipitate them, and thereafter active carbon is added to the slurry to adsorb the dissolved sulfate ions, it is possible to shorten the reaction time and the aging time and to obtain crystals which are easily filtered. Moreover, the phosphoric acid prepared by subsequently separating the solid components suffers from no turbidity after being stored. Accordingly, it is clear that the reaction operation is easy, the series of steps can be operated continuously and the reactor and the filter can be simplified and miniaturized. In the process of this invention, the barium compound is added to the extracted phosphoric acid. In this step, the amount of barium compound used should be less than the stoichiometric equivalent to the amount of sulfate ions in the extracted phosphoric acid, in order to prevent contamination of barium ions and the subsequent formation of turbidity in the phosphoric acid after the separation of the solid components. In order to lighten the load for the following active carbon treatment, the amount of the barium compound should preferably be in the range of 80-95 mole % relative to the amount of sulfate ions in the phosphoric acid because an excess addition of the barium compound causes difficulties as mentioned above. When such an amount of the barium compound is used, and by the following active carbon treatment, the amount of the dissolved sulfate ion in the phosphoric acid can be decreased to less than 30 wt. ppm. Suitable barium compounds for use in the process of this invention include barium hydroxide, barium carbonate, barium phosphate, barium sulfide, barium nitrate, barium chloride and the like. When contamination by the anion must be prevented, it is preferred to use barium hydroxide, barium carbonate or barium phosphate. When barium sulfide is used, most of the excess sulfide is removed from the system as hydrogen sulfide and the dissolved hydrogen sulfide can be easily removed by injection of air and the like. Thus, contamination can be prevented. As described below, active carbon is added after the addition of the barium compound. After the solid components are separated from the resulting slurry, they can be calcined to obtain a calcined product containing a main component of barium sulfide. This calcined product can be used as the barium compound in this invention whereby the cost of the expensive barium compound can be decreased. These barium compounds can be used in any form such as solids, aqueous solutions, phosphoric acid solutions and the like. The treatment time in the barium compound step is not critical. For example, in a continuous process, it is sufficient to provide a suitable residence time for contacting a phosphoric acid with the barium compound. In a batch process, it is possible to conduct the subsequent step after completing the addition of the barium compound without aging. Thereafter, the active carbon is added to the slurry prepared by treatment with the barium compound. The amount of the active carbon used is dependent upon the concentration of the dissolved sulfate ions and the temperature, and especially upon the concentration of phosphoric acid. When the latter is higher than 70 wt. % as H 3 PO 4 , the amount of active carbon can be small and is usually in the range of 0.05 - 5 wt. % relative to the amount of P 2 O 5 in the extracted phosphoric acid. The concentration of sulfate ion can be less than 30 wt. ppm in such a phosphoric acid (higher than 70 wt. % of H 3 PO 4 ) prepared by removing 80-95% of the sulfate ions by the precipitation with the barium compound from extracted phosphoric acid (H 3 PO 4 :20-40 wt. % as non-concentrated extracted phosphoric acid; SO 4 500-5000 wt. ppm). When the treatment of active carbon is conducted after the precipitation of the sulfate ions as barium sulfate, the sulfate ions can be removed to only a trace level. On the contrary, when the active carbon only is added to the extracted phosphoric acid to remove the sulfate ions, the adsorption is quite small so that it is uneconomincal. It has moreover been found that the aging time required for the barium sulfate can be greatly shortened by the treatment with active carbon. At least one day has usually been required for aging of barium sulfate crystals. Otherwise, even though the solid components are filtered to obtain a clear solution, turbidity is caused in storage. However, when treated with active carbon, the aging time can be shortened to only several hours. The reason is not completely clear, but it is theorized that the barium ions and sulfate ions are adsorbed in some special form on the active carbon by a synergistic effect. When the barium compound is added to the extracted phosphoric acid and then the active carbon added, the following process is theorized. 1. The dissolved barium ions are adsorbed on the active carbon. 2. The aging time is shortened by the adsorption of the barium ions. 3. The sulfate ions are further adsorbed on the active carbon to a high degree by the adsorption of barium ions. The concentration of phosphoric acid used in the process of this invention, the temperature for the treatment of the barium compound and the treatment of active carbon, are not critical. In order to decrease the amount of active carbon used and to remove the sulfate ions to a high degree, it is preferred that the concentration of the phosphoric acid as H 3 PO 4 be higher than 70 wt. % and temperature of the treatment be 30°-80° C. After the active carbon treatment, the solid components are separated from the slurry to obtain a pure phosphoric acid from which sulfate ions are removed. The solid components have excellent filtering properties. The solid components contain main components of barium sulfate and active carbon. It has been found that a calcined product containing a main component of barium sulfide can be obtained by calcining the solid components. This calcined product can be used as the barium compound for removing the sulfate ions from the extracted phosphoric acid. The calcination should be conducted in an inert gas, especially in nitrogen gas, in order to prevent the combustion of active carbon. The temperature for calcination should be in the range of 800°-1200° C. so as to form barium sulfide by reduction of barium sulfate with active carbon. The process of this invention can be conducted in an economical manner by reusing the calcined product as a part or all of the barium compound used in the treatment of this invention. As is clear from the description above, in accordance with the process of this invention, the required conditions of control of operation are not complicated; the aging time for the slurry can be greatly shortened; the crystals have excellent filtering properties superior to those of the solid components formed only by treatment with a barium compound; the reactor and the filter used can be simplified and miniaturized; all steps can be conducted in a continuous process; super-fine crystals are not formed; and turbidity of the resulting phosphoric acid does not occur after the separation of the solid components during storage or various other treatments. Moreover, the calcined product prepared by calcining the residual solid components separated from the slurry, can be used as the barium compound, whereby the amount of the barium compound consumed can be decreased to attain an advantageous process. Having generally described the invention, a more complete understanding can be obtained by reference to certain specific examples, which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified. The terms "%" and "ppm" are respectively "% by weight" and "ppm by weight". The transmittance was measured by using water as a blank. In the filtering operation, a G-2 glass filter which was precoated with a filtering auxiliary agent Fine-flow (manufactured by Showa Kagaku Kogyo K.K.) in a thickness of 3 mm was used under a pressure difference of 0.92 kg/cm 2 . EXAMPLE 1 A calcined phosphate rock (Morocco) was treated with sulfuric acid to obtain a crude wet process phosphoric acid (H 3 PO 4 -47.6%; SO 4 -0.92%). The crude wet process phosphoric acid was contacted with n-butanol in a multi-stage counter-current extraction. The extracted solution of phosphoric acid was back-extracted with water to obtain an extracted phosphoric acid solution (H 3 PO 4 -33.0%; SO 4 -0.320%). The extracted phosphoric acid solution was concentrated under a reduced pressure to obtain an extracted phosphoric acid (H 3 PO 4 -92.6%; SO 4 -0.888%). A barium salt-phosphoric acid mixture (H 3 PO 4 -50%; Ba-6.00%) was prepared by dissolving barium carbonate in pure phosphoric acid. A 205.0 g sample of the barium salt-phosphoric acid mixture was added to 1000 g of the extracted phosphoric acid at 80° C. with stirring during about 1 hour. The mixture was kept at 80° C. for 6 hours to age it thereby obtaining a slurry having 216 ppm of the dissolved sulfate as SO.sub. 4. The slurry was gradually cooled to 60° C. and 15.0 g of powdery active carbon was added. The mixture was stirred for 3 hours and filtered. The filtering speed was 1.01 m 3 /m 2 hr. and the filtrate was a clear solution. (H 3 PO 4 -86.9%; SO 4 -25.3 ppm; transmittance-101%). The residue was used in Example 2. When the filtrate was stored for 1 month, no change was found. REFERENCE EXAMPLE 1 The slurry (216 ppm of dissolved SO 4 ) of Example 1 was admixed with 4.80 g of the barium salt-phosphoric acid mixture of Example 1 at 80° C. The mixture was gradually cooled and kept at 60° C. for 3 hours for aging and was filtered. The filtering speed was 0.43 m 3 /m 2 hr. and the filtrate was a clear solution (SO 4 -17.2 ppm; transmittance-101%). When the filtrate was stored for 1 month, the transmittance was decreased to 91%. REFERENCE EXAMPLE 2 A 15 g sample of powdery active carbon was added to 1000 g of the extracted phosphoric acid of Example 1. The mixture was stirred at 60° C. for 3 hours and was filtered. The concentration of SO 4 was not changed. EXAMPLE 2 This residue of Example 1 was washed with water to obtain 50.3 g of the composition: BaSO 4 -40.8%; C-28.4%; Water, etc.-30.8%. The composition was calcined at 1000° C. for about 3 hours to obtain 15.5 g of black product (Ba:77%). The crushed black product and 10.0 g of barium carbonate were dissolved in pure phosphoric acid to obtain 315 g of barium salt-phosphoric acid mixture (H 3 PO 4 :50%; Ba:6.00%). A 205.0 g sample of the barium salt-phosphoric acid mixture was added to 1000 g of the extracted phosphoric acid of Example 1 to treat it under the same conditions. The product was treated with the powdery active carbon to obtain substantially the same results of Example 1. Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the invention as set forth herein.
A process for removing sulfate ions from extracted phosphoric acid which is substantially free of metallic ion contaminants, which comprises adding less than the stoichiometric equivalent of a barium compound relative to the amount of dissolved sulfate ion to said extracted phosphoric acid to form barium sulfate crystals, adding active carbon to the resulting slurry, separating the solid components from the slurry and recovering purified phosphoric acid.
Concisely explain the essential features and purpose of the invention.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention The present invention relates to a process for removing sulfate ions from extracted phosphoric acid.", "Description of the Prior Art In the past, it has been known that wet process phosphoric acid which is produced by sulfuric acid decomposition of phosphate rock, can be extracted by an organic solvent which dissolves phosphoric acid and has low solubility to water.", "Such solvents include various alcohols, ketones, ethers, phosphoric acid esters, amines, and the like.", "After this treatment, the phosphoric acid is extracted by water from the extracted solution of phosphoric acid (hereinafter referred to as the "extraction method").", "In this specification, phosphoric acid prepared by purifying the crude phosphoric acid from the wet process (including a pretreated acid) by the extraction method (including a concentration step) will be referred to as the "extracted phosphoric acid".", "The phosphoric acid produced by the wet process contains various metallic ion impurities derived from a phosphate rock and sulfate ions derived from sulfuric acid.", "Using the extraction method, the metallic ion impurities can be effectively removed.", "However, the sulfate ions are not satisfactorily removed and a large amount of sulfate ions still remain in the extracted phosphoric acid.", "The phosphoric acid used in industrial products, medicines and foods must be a pure phosphoric acid having substantially no sulfate ions, such as one having less than 30 wt.", "ppm as SO 4 as in the Japanese Industrial Standard.", "In order to decrease sulfate ions sufficiently for use of the phosphoric acid in the industrial applications, it is necessary to remove sulfate ions from the wet process phosphoric acid or from the extracted phosphoric acid.", "It has been known to remove sulfate ions as calcium sulfate from a wet process phosphoric acid by adding a calcium compound such as phosphate rock, calcium hydroxide or calcium carbonate.", "However, calcium sulfate has a relatively high solubility.", "Accordingly, even though a large excess of the calcium compound is used, sulfate ions remain present in a concentration in the range of 1000-2000 wt.", "ppm as SO 4 .", "It is difficult to lower the concentration of the sulfate ions.", "Even when the desulfated wet process phosphoric acid is further purified by extraction, sulfate ions in a concentration of at least 500 wt.", "ppm as SO 4 remain in the extracted phosphoric acid.", "It has also been known to remove sulfate ions as barium sulfate and thereby lower the concentration by using a barium compound.", "However, it is not preferred to use that method on the wet process phosphoric acid because of the following reasons.", "a. The sulfate ion content is higher than that of the extracted phosphoric acid whereby the consumption of the expensive barium compound is high.", "b. Hydrofluorosilicic acid is generally present whereby the barium compound is consumed for the formation of crystals of barium fluorosilicate.", "c. The concentrations of the sulfate ion and hydrofluorosilicic acid fluctuates depending upon the fluctuations in the composition of the phosphate rock and the operating conditions are critical whereby the phosphoric acid may be contaminated by barium ions because of an inadvertant excess addition of the barium compound.", "d. Hydrofluoric acid is also present.", "Accordingly, the selection of a suitable material for the filter used for separating the barium sulfate is restricted.", "Moreover, it is difficult to use stainless steel.", "e. The crystals of barium sulfate are fine and smaller than those of the extracted phosphoric acid.", "This may be caused by the presence of organic materials and metallic impurities.", "Moreover, the viscosity of the slurry is high even though the concentration of phosphoric acid is low.", "Accordingly, the separation of barium sulfate is difficult.", "SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a process for removing sulfate ions from extracted phosphoric acid wherein the operation for precipitating the sulfate ions is easy and stable and the reaction time and the aging time are shortened so that continuous operation of the series of steps is feasible with a simplification and miniaturization of the apparatus required.", "It is another object of the present invention to provide a process for substantially removing sulfate ions from extracted phosphoric acid to the degree required for the use of the phosphoric acid in industrial products, medicines and foods, without the formation of super-fine crystals and without formation of turbidity during storage or in the various uses, whereby a shorter aging time is required for prevention of turbidity after the filtering operation in a continuous system.", "These and other objects of this invention as will hereinafter become clear have been attained by providing a process for substantially removing sulfate ions from extracted phosphoric acid which comprises adding a barium compound to the extracted phosphoric acid, then adding active carbon to the resulting slurry and separating the solid components from the slurry.", "DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The inventors have made several studies of processes for substantially removing sulfate ions from extracted phosphoric acid as barium sulfate.", "As a result, it has been found that super-fine crystals of barium sulfate which are very much smaller than the size of fine crystals are formed by the reaction of sulfate ions with barium ions.", "Moreover, turbidity is formed by long storage after the separation of the barium sulfate, or in the preparation of condensed phosphoric acids.", "It has also been found that these phenomena do not occur when no barium compound treatment is used.", "Accordingly, it is clear that the turbidity phenomenon is caused by the barium compound treatment.", "It has been determined that the phenomena are caused by the dissolved barium ions in the phosphoric acid.", "It is known that barium sulfate is an insoluble salt.", "Its solubility product in water is in the range of 8.7 × 10.", "sup.", "-11 to 2.8 × 10.", "sup.", "-10 , quite insoluble.", "However, according to measurements, the solubility product of barium sulfate in pure phosphoric acid varies in the range of from 1 × 10 -6 to 2 × 10.", "sup.", "-9 depending upon the concentration of its phosphoric acid and the temperature.", "It is clear that barium sulfate is still sparingly soluble but is relatively more soluble in phosphoric acid than in water.", "In accordance with these new findings, the present inventors have determined that the formation of super-fine crystals and turbidity can be prevented by controlling the amount of the barium compound added so that the amount of remaining dissolved sulfate ions is at least 5 wt.", "ppm as SO 4 in the extracted phosphoric acid.", "However, the extracted phosphoric acid contains dissolved sulfate ions in the range of 500-5000 wt.", "ppm as SO 4 .", "Therefore, it is difficult to decrease the SO 4 content from 500-5000 wt.", "ppm to 5-30 wt.", "ppm by the single step of addition of the barium compound.", "The problems encountered involve the accuracy of analysis of SO 4 , the purity of the barium compound, the accuracy of weighing, etc.", "As a result, there is a high possibility of excess addition of the barium compound.", "When a plurality of additions of the barium compound are used each followed by a measurement of the sulfate ion concentration in the phosphoric acid, the concentration of the dissolved sulfate can be adjusted into the proper range in relative safety.", "However, in this technique, super-saturation of barium sulfate is relatively stable whereby it is necessary to age the slurry for a long time.", "Accordingly, a large size reactor is required and a batch system must be used.", "The inventors have also found that it is necessary to age the slurry for a long time before the separation of the solid components in order to prevent turbidity in storage even though clear phosphoric acid can be obtained by separating the solid compounds from the slurry resulting from the addition of the barium compound.", "The present inventors have discovered the above-mentioned problems which were consequently considered in determining a process for removing sulfate ions from extracted phosphoric acid by addition of a barium compound.", "As a result, it has been found that when a barium compound is added to extracted phosphoric acid to convert a part of the sulfate ions to barium sulfate and to precipitate them, and thereafter active carbon is added to the slurry to adsorb the dissolved sulfate ions, it is possible to shorten the reaction time and the aging time and to obtain crystals which are easily filtered.", "Moreover, the phosphoric acid prepared by subsequently separating the solid components suffers from no turbidity after being stored.", "Accordingly, it is clear that the reaction operation is easy, the series of steps can be operated continuously and the reactor and the filter can be simplified and miniaturized.", "In the process of this invention, the barium compound is added to the extracted phosphoric acid.", "In this step, the amount of barium compound used should be less than the stoichiometric equivalent to the amount of sulfate ions in the extracted phosphoric acid, in order to prevent contamination of barium ions and the subsequent formation of turbidity in the phosphoric acid after the separation of the solid components.", "In order to lighten the load for the following active carbon treatment, the amount of the barium compound should preferably be in the range of 80-95 mole % relative to the amount of sulfate ions in the phosphoric acid because an excess addition of the barium compound causes difficulties as mentioned above.", "When such an amount of the barium compound is used, and by the following active carbon treatment, the amount of the dissolved sulfate ion in the phosphoric acid can be decreased to less than 30 wt.", "ppm.", "Suitable barium compounds for use in the process of this invention include barium hydroxide, barium carbonate, barium phosphate, barium sulfide, barium nitrate, barium chloride and the like.", "When contamination by the anion must be prevented, it is preferred to use barium hydroxide, barium carbonate or barium phosphate.", "When barium sulfide is used, most of the excess sulfide is removed from the system as hydrogen sulfide and the dissolved hydrogen sulfide can be easily removed by injection of air and the like.", "Thus, contamination can be prevented.", "As described below, active carbon is added after the addition of the barium compound.", "After the solid components are separated from the resulting slurry, they can be calcined to obtain a calcined product containing a main component of barium sulfide.", "This calcined product can be used as the barium compound in this invention whereby the cost of the expensive barium compound can be decreased.", "These barium compounds can be used in any form such as solids, aqueous solutions, phosphoric acid solutions and the like.", "The treatment time in the barium compound step is not critical.", "For example, in a continuous process, it is sufficient to provide a suitable residence time for contacting a phosphoric acid with the barium compound.", "In a batch process, it is possible to conduct the subsequent step after completing the addition of the barium compound without aging.", "Thereafter, the active carbon is added to the slurry prepared by treatment with the barium compound.", "The amount of the active carbon used is dependent upon the concentration of the dissolved sulfate ions and the temperature, and especially upon the concentration of phosphoric acid.", "When the latter is higher than 70 wt.", "% as H 3 PO 4 , the amount of active carbon can be small and is usually in the range of 0.05 - 5 wt.", "% relative to the amount of P 2 O 5 in the extracted phosphoric acid.", "The concentration of sulfate ion can be less than 30 wt.", "ppm in such a phosphoric acid (higher than 70 wt.", "% of H 3 PO 4 ) prepared by removing 80-95% of the sulfate ions by the precipitation with the barium compound from extracted phosphoric acid (H 3 PO 4 :20-40 wt.", "% as non-concentrated extracted phosphoric acid;", "SO 4 500-5000 wt.", "ppm).", "When the treatment of active carbon is conducted after the precipitation of the sulfate ions as barium sulfate, the sulfate ions can be removed to only a trace level.", "On the contrary, when the active carbon only is added to the extracted phosphoric acid to remove the sulfate ions, the adsorption is quite small so that it is uneconomincal.", "It has moreover been found that the aging time required for the barium sulfate can be greatly shortened by the treatment with active carbon.", "At least one day has usually been required for aging of barium sulfate crystals.", "Otherwise, even though the solid components are filtered to obtain a clear solution, turbidity is caused in storage.", "However, when treated with active carbon, the aging time can be shortened to only several hours.", "The reason is not completely clear, but it is theorized that the barium ions and sulfate ions are adsorbed in some special form on the active carbon by a synergistic effect.", "When the barium compound is added to the extracted phosphoric acid and then the active carbon added, the following process is theorized.", "The dissolved barium ions are adsorbed on the active carbon.", "The aging time is shortened by the adsorption of the barium ions.", "The sulfate ions are further adsorbed on the active carbon to a high degree by the adsorption of barium ions.", "The concentration of phosphoric acid used in the process of this invention, the temperature for the treatment of the barium compound and the treatment of active carbon, are not critical.", "In order to decrease the amount of active carbon used and to remove the sulfate ions to a high degree, it is preferred that the concentration of the phosphoric acid as H 3 PO 4 be higher than 70 wt.", "% and temperature of the treatment be 30°-80° C. After the active carbon treatment, the solid components are separated from the slurry to obtain a pure phosphoric acid from which sulfate ions are removed.", "The solid components have excellent filtering properties.", "The solid components contain main components of barium sulfate and active carbon.", "It has been found that a calcined product containing a main component of barium sulfide can be obtained by calcining the solid components.", "This calcined product can be used as the barium compound for removing the sulfate ions from the extracted phosphoric acid.", "The calcination should be conducted in an inert gas, especially in nitrogen gas, in order to prevent the combustion of active carbon.", "The temperature for calcination should be in the range of 800°-1200° C. so as to form barium sulfide by reduction of barium sulfate with active carbon.", "The process of this invention can be conducted in an economical manner by reusing the calcined product as a part or all of the barium compound used in the treatment of this invention.", "As is clear from the description above, in accordance with the process of this invention, the required conditions of control of operation are not complicated;", "the aging time for the slurry can be greatly shortened;", "the crystals have excellent filtering properties superior to those of the solid components formed only by treatment with a barium compound;", "the reactor and the filter used can be simplified and miniaturized;", "all steps can be conducted in a continuous process;", "super-fine crystals are not formed;", "and turbidity of the resulting phosphoric acid does not occur after the separation of the solid components during storage or various other treatments.", "Moreover, the calcined product prepared by calcining the residual solid components separated from the slurry, can be used as the barium compound, whereby the amount of the barium compound consumed can be decreased to attain an advantageous process.", "Having generally described the invention, a more complete understanding can be obtained by reference to certain specific examples, which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified.", "The terms "%"", "and "ppm"", "are respectively "% by weight"", "and "ppm by weight".", "The transmittance was measured by using water as a blank.", "In the filtering operation, a G-2 glass filter which was precoated with a filtering auxiliary agent Fine-flow (manufactured by Showa Kagaku Kogyo K.K.) in a thickness of 3 mm was used under a pressure difference of 0.92 kg/cm 2 .", "EXAMPLE 1 A calcined phosphate rock (Morocco) was treated with sulfuric acid to obtain a crude wet process phosphoric acid (H 3 PO 4 -47.6%;", "SO 4 -0.92%).", "The crude wet process phosphoric acid was contacted with n-butanol in a multi-stage counter-current extraction.", "The extracted solution of phosphoric acid was back-extracted with water to obtain an extracted phosphoric acid solution (H 3 PO 4 -33.0%;", "SO 4 -0.320%).", "The extracted phosphoric acid solution was concentrated under a reduced pressure to obtain an extracted phosphoric acid (H 3 PO 4 -92.6%;", "SO 4 -0.888%).", "A barium salt-phosphoric acid mixture (H 3 PO 4 -50%;", "Ba-6.00%) was prepared by dissolving barium carbonate in pure phosphoric acid.", "A 205.0 g sample of the barium salt-phosphoric acid mixture was added to 1000 g of the extracted phosphoric acid at 80° C. with stirring during about 1 hour.", "The mixture was kept at 80° C. for 6 hours to age it thereby obtaining a slurry having 216 ppm of the dissolved sulfate as SO.", "sub.", "The slurry was gradually cooled to 60° C. and 15.0 g of powdery active carbon was added.", "The mixture was stirred for 3 hours and filtered.", "The filtering speed was 1.01 m 3 /m 2 hr.", "and the filtrate was a clear solution.", "(H 3 PO 4 -86.9%;", "SO 4 -25.3 ppm;", "transmittance-101%).", "The residue was used in Example 2.", "When the filtrate was stored for 1 month, no change was found.", "REFERENCE EXAMPLE 1 The slurry (216 ppm of dissolved SO 4 ) of Example 1 was admixed with 4.80 g of the barium salt-phosphoric acid mixture of Example 1 at 80° C. The mixture was gradually cooled and kept at 60° C. for 3 hours for aging and was filtered.", "The filtering speed was 0.43 m 3 /m 2 hr.", "and the filtrate was a clear solution (SO 4 -17.2 ppm;", "transmittance-101%).", "When the filtrate was stored for 1 month, the transmittance was decreased to 91%.", "REFERENCE EXAMPLE 2 A 15 g sample of powdery active carbon was added to 1000 g of the extracted phosphoric acid of Example 1.", "The mixture was stirred at 60° C. for 3 hours and was filtered.", "The concentration of SO 4 was not changed.", "EXAMPLE 2 This residue of Example 1 was washed with water to obtain 50.3 g of the composition: BaSO 4 -40.8%;", "C-28.4%;", "Water, etc.", "-30.8%.", "The composition was calcined at 1000° C. for about 3 hours to obtain 15.5 g of black product (Ba:77%).", "The crushed black product and 10.0 g of barium carbonate were dissolved in pure phosphoric acid to obtain 315 g of barium salt-phosphoric acid mixture (H 3 PO 4 :50%;", "Ba:6.00%).", "A 205.0 g sample of the barium salt-phosphoric acid mixture was added to 1000 g of the extracted phosphoric acid of Example 1 to treat it under the same conditions.", "The product was treated with the powdery active carbon to obtain substantially the same results of Example 1.", "Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the invention as set forth herein." ]
CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 13/617,231, filed on Sep. 14, 2012, entitled “Mobile Device and Optical Imaging Lens Thereof” which claims priority from Taiwan Patent Application No. 101111443, filed on Mar. 30, 2012, the disclosures of which are hereby incorporated by reference in their entirety for all purposes. TECHNICAL FIELD [0002] The present invention relates to a mobile device and an optical imaging lens thereof, and particularly, relates to a mobile device applying an optical imaging lens having five lens elements and an optical imaging lens thereof. BACKGROUND OF THE INVENTION [0003] The ever-increasing demand for smaller sized mobile devices, such as cell phones, digital cameras, etc. has correspondingly triggered a growing need for smaller sized photography modules contained therein. Size reductions may be contributed from various aspects of the mobile devices, which includes not only the charge coupled device (CCD) and the complementary metal-oxide semiconductor (CMOS), but also the optical imaging lens mounted therein. When reducing the size of the optical imaging lens, however, achieveing good optical characteristics becomes a challenging problem. [0004] US Patent Publication No. 20100253829, US Patent Publication No. 2011013069, US Patent Publication No. 20110249346, US Patent Publication No. 20100254029, U.S. Pat. No. 7,826,151, U.S. Pat. No. 7,864,454, U.S. Pat. No. 7,911,711, U.S. Pat. No. 8,072,695, Taiwan Patent No. M368072, Taiwan Patent No. M369460 and Taiwan Patent No. M369459 all disclosed an optical imaging lens constructed with an optical imaging lens having five lens elements. Those disclosed optical imaging lenses involved use of a shortened length of the optical imaging lens; however, some of lengths of the optical imaging lens remained too long. For example, in the first embodiment of Taiwan Patent No. M368072, the length of the optical imaging lens is around 5.61 mm, which is not beneficial for the smaller design of mobile devices. [0005] How to effectively shorten the lengths of the optical imaging lens is one of the most important topics in the industry to peruse the trend of smaller and smaller mobile devices. Each of the aforesaid patent documents faces the limitation of the size of the mobile device due to the problem of reducing length of the optical imaging lens. Therefore, there is needed to develop optical imaging lens with shorter lengths, while also having good optical characters. SUMMARY OF THE INVENTION [0006] An object of the present invention is to provide a mobile device and an optical imaging lens thereof. With controlling the convex or concave shape of the surfaces of the lens elements, the central thickness along the optical axis, and the air gap between two lens elements, etc., the lengths of the optical imaging lens is shortened and meanwhile the good optical characters, such as high resolution and the system performance, are sustained. [0007] In an exemplary embodiment, an optical imaging lens comprises, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, and a fifth lens element. The first lens element has positive refractive power and comprises a convex object-side curved surface. The second lens element has negative refractive power and comprises a concave image-side curved surface. The third lens element comprises an object-side curved surface and an image-side curved surface, and the object-side curved surface comprises a concave portion in a vicinity of a periphery of said third lens element and the image-side curved surface comprises a convex portion in a vicinity of a periphery of the third lens element. The fourth lens element comprises a convex image-side curved surface and the fifth lens element comprises an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a convex portion in a vicinity of the optical axis and the image-side curved surface comprises a concave portion in a vicinity of the optical axis. Lens as a whole has only the five lens elements with refractive power, wherein a central thickness of the second lens element along the optical axis is T2, a sum of all air gaps from the first lens element to the fifth lens element along the optical axis is Gaa, and they satisfy the relation: [0000] 0.20 <T 2<0.50 (mm); and [0000] 0.27<( T 2 /Gaa )<0.40. [0008] In another exemplary embodiment, other central thickness of lens element along the optical axis and/or other ratio of the central thickness of lens element along the optical axis to the sum of all air gaps could be further controlled, and an example among them is controlling the relation of a central thickness of the third lens element along the optical axis, T3, and the sum of all air gaps from the first lens element to the fifth lens element along the optical axis, Gaa, to satisfy the relation: [0000] 0.30<( T 3 /Gaa )<0.45. [0009] Another example embodiment comprises controlling T3 to further satisfy the relation: [0000] 0.20 <T 3<0.60 (mm). [0010] Yet, another example embodiment comprises controlling T2 and Gaa to further satisfy the relation: [0000] 0.21 <T 2<0.47 (mm); and [0000] 0.28<( T 2 /Gaa )<0.40. [0011] Yet, another example embodiment comprises controlling T3 and Gaa to further satisfy the relation: [0000] 0.25 <T 3<0.57 (mm); and [0000] 0.31<( T 3 /Gaa )<0.45. [0012] Aforesaid exemplary embodiments are not limited and could be selectively incorporated in other embodiments described herein. [0013] Lens elements in example embodiments, such as the aforesaid first lens element, second lens element, third lens element, fourth lens element, and fifth lens element, are preferable made by plastic lens element with injection molding. Therefore, the technical barrier and the cost may be affected by the thickness of lens element. For example, if the central thickness of the second lens element along the optical axis, T2, is less than the lower limit, 0.2 (mm), the center of the second lens element may be too thin and cause melting plastic material to fail to pass the mold, and compared with currently technical level, the difficulty and cost for production in such situations are too high. Therefore, the lower limits of the above ranges of T2 and T3 are determined based on currently technical level. Further, the thicknesses of the first lens element, the second lens element, the third lens element, the fourth lens element, and fifth lens element affect the length of the optical imaging lens. For example, if the central thickness of the second lens element along the optical axis, T2, exceeds the upper limit, 0.5 (mm), the second lens element may be too thick and cause the length of the optical imaging lens to be too long and fail to match the request of smaller optical imaging lens. Therefore, the upper limits of above ranges of T2 and T3 are determined based on the preferable length of the optical imaging lens. [0014] In example embodiments, an aperture stop is provided for adjusting the input of light of the system. For example, the aperture stop is selectively provided but not limited to be positioned at the object side of the first lens element, or positioned between the first lens element and the second lens element. [0015] In some exemplary embodiments, more details about the convex or concave surface structure and/or the refractive power could be incorporated for one specific lens element or broadly for plural lens elements to enhance the control for the system performance and/or resolution. For example, for the second lens element, an object-side curved surface is comprised, but the object-side curved surface need not be limited to a convex portion in a vicinity of a periphery of the second lens element. An example for illustrating the details broadly for plural lens elements comprises the first lens element having positive refractive power and comprising a convex object-side curved surface; the second lens element having negative refractive power and comprising an object-side curved surface and a concave image-side curved surface; the third lens element comprising an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a convex portion in a vicinity of the optical axis and a concave portion in a vicinity of a periphery of the third lens element, and the image-side curved surface comprises a concave portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the third lens element; the fourth lens element having positive refractive power and comprising a concave object-side curved surface and a convex image-side curved surface; and the fifth lens element having negative refractive power and comprising an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the fourth lens element, and the image-side curved surface comprises a concave portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the fourth lens element. Another example for illustrating the details broadly for plural lens elements comprises the first lens element having positive refractive power and comprising a convex object-side curved surface and a concave image-side curved surface; the second lens element having negative refractive power and comprising an object-side curved surface and a concave image-side curved surface, wherein the object-side curved surface of the second lens element comprises a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the second lens element; the third lens element comprising an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a concave portion in a vicinity of the optical axis and a concave portion in a vicinity of a periphery of the third lens element, and the image-side curved surface comprises a convex portion in a vicinity of a periphery of the third lens element; the fourth lens element having positive refractive power and comprising a concave object-side curved surface and a convex image-side curved surface; and the fifth lens element having negative refractive power and comprising an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the fifth lens element, and the image-side curved surface comprises a concave portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the fifth lens element. Exemplary embodiments for incorporating details broadly for plural lens elements are not limited to the above examples. [0016] Further, exemplary embodiments could provide more details about the structure, the refractive power, and/or the aperture stop position for a specific lens element or broadly for plural lens elements to fit variable requests. For example, based on the aforesaid examples, an example embodiment comprises the first lens element comprising a convex image-side curved surface, wherein the object-side curved surface of the second lens element comprises a concave portion in a vicinity of the optical axis and a concave portion in a vicinity of a periphery of the second lens element, the third lens element having positive refractive power, and an aperture stop provided at the object side of the first lens element. Another example embodiment is provided with the first lens element comprising a convex image-side curved surface, wherein the object-side curved surface of the second lens element comprises a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the second lens element, the third lens element having negative refractive power, and an aperture stop provided at the object side of the first lens element. Another example embodiment is provided with the first lens element comprising a concave image-side curved surface, the object-side curved surface of the second lens element comprising a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the second lens element, the third lens element having positive refractive power, and an aperture stop provided between the first lens element and the second lens element. Another example embodiment is provided with the first lens element comprising a concave image-side curved surface, the object-side curved surface of the second lens element comprises a convex portion in a vicinity of the optical axis and a concave portion in a vicinity of a periphery of the second lens element, the third lens element having positive refractive power, and an aperture stop provided at the object side of the first lens element. Similarly, based on the later of the aforesaid examples, more examples could be obtained with the further details listed below, including an example embodiment is provided with the third lens element having positive refractive power, and the third lens element the image-side curved surface comprising a convex portion in a vicinity of the optical axis. Another example embodiment is provided with the third lens element having negative refractive power, and the image-side curved surface of the third lens element comprising a concave portion in a vicinity of the optical axis. Another example embodiment is provided with the third lens element having negative refractive power, and the image-side curved surface of the third lens element comprising a convex portion in a vicinity of the optical axis. It is noted that the examples above may be incorporated into other embodiments if no inconsistencies arise. [0017] In another exemplary embodiment, a mobile device comprises a housing and an optical imaging lens assembly positioned in the housing. The optical imaging lens assembly comprises a lens barrel, any of aforesaid example embodiments of optical imaging lens, a module housing unit, and an image sensor. The lens comprising five lens elements with refractive power as a whole is positioned in the lens barrel, the module housing unit is for positioning the optical imaging lens, and the image sensor is positioned at the image-side of the optical imaging lens. [0018] In exemplary embodiments, the module housing unit comprises, but is not limited to, an image sensor base and an auto focus module, wherein the image sensor base is for fixing the image sensor, and the auto focus module comprises a lens seat for positioning the optical imaging lens to control the focusing of the optical imaging lens. [0019] Through controlling the ratio of at least one central thickness of lens element along the optical axis to a sum of all air gaps between the five lens elements along the optical axis in a predetermined range, and incorporated with the arrangement of the convex or concave shape of the surfaces of the lens element(s) and/or refraction power, the mobile device and the optical imaging lens thereof in exemplary embodiments achieve good optical characters and effectively shorten the lengths of the optical imaging lens. BRIEF DESCRIPTION OF THE DRAWINGS [0020] Exemplary embodiments will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: [0021] FIG. 1 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment; [0022] FIG. 2 shows another cross-sectional view of a lens element of the optical imaging lens according to an example embodiment; [0023] FIG. 3 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment; [0024] FIG. 4 shows a table of aspherical data of the optical imaging lens according to an example embodiment; [0025] FIG. 5( a ) shows the longitudinal spherical aberration, FIGS. 5( b ) and 5 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 5( d ) shows the distortion of the optical imaging lens of FIG. 1 ; [0026] FIG. 6 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment; [0027] FIG. 7 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment; [0028] FIG. 8 shows a table of aspherical data of the optical imaging lens according to an example embodiment; [0029] FIG. 9( a ) shows the longitudinal spherical aberration, FIGS. 9( b ) and 9 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 9( d ) shows the distortion of the optical imaging lens of FIG. 6 ; [0030] FIG. 10 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment; [0031] FIG. 11 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment; [0032] FIG. 12 shows a table of aspherical data of the optical imaging lens according to an example embodiment; [0033] FIG. 13( a ) shows the longitudinal spherical aberration, FIGS. 13( b ) and 13 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 13( d ) shows the distortion of the optical imaging lens of FIG. 10 ; [0034] FIG. 14 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment; [0035] FIG. 15 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment; [0036] FIG. 16 shows a table of aspherical data of the optical imaging lens according to an example embodiment; [0037] FIG. 17( a ) shows the longitudinal spherical aberration, FIGS. 17( b ) and 17 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 17( d ) shows the distortion of the optical imaging lens of FIG. 14 ; [0038] FIG. 18 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment; [0039] FIG. 19 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment; [0040] FIG. 20 shows a table of aspherical data of the optical imaging lens according to an example embodiment; [0041] FIG. 21( a ) shows the longitudinal spherical aberration, FIGS. 21( b ) and 21 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 21( d ) shows the distortion of the optical imaging lens of FIG. 18 ; [0042] FIG. 22 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment; [0043] FIG. 23 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment; [0044] FIG. 24 shows a table of aspherical data of the optical imaging lens according to an example embodiment; [0045] FIG. 25( a ) shows the longitudinal spherical aberration, FIGS. 25( b ) and 25 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 25( d ) shows the distortion of the optical imaging lens of FIG. 22 ; [0046] FIG. 26 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment; [0047] FIG. 27 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment; [0048] FIG. 28 shows a table of aspherical data of the optical imaging lens according to the seventh embodiment of the present invention; [0049] FIG. 29( a ) shows the longitudinal spherical aberration, FIGS. 29( b ) and 29 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 29( d ) shows the distortion of the optical imaging lens of FIG. 26 ; [0050] FIG. 30 shows a comparison table for the values of T2, T3, T2/Gaa and T3/Gaa of example embodiments; [0051] FIG. 31 shows a structure of an example embodiment of a mobile device; [0052] FIG. 32 shows an enlarged view of a structure of an example embodiment of a mobile device; and [0053] FIG. 33 shows another enlarged view of a structure of an example embodiment of a mobile device. DETAILED DESCRIPTION OF THE INVENTION [0054] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features. Persons having ordinary skill in the art will understand other varieties for implementing example embodiments, including those described herein. The drawings are not limited to specific scale and similar reference numbers are used for representing similar elements. As used in the disclosures and the appended claims, the terms “example embodiment,” “exemplary embodiment,” and “present embodiment” do not necessarily refer to a single embodiment, although it may, and various example embodiments may be readily combined and interchanged, without departing from the scope or spirit of the present invention. Furthermore, the terminology as used herein is for the purpose of describing example embodiments only and is not intended to be a limitation of the invention. In this respect, as used herein, the term “in” may include “in” and “on”, and the terms “a”, “an” and “the” may include singular and plural references. Furthermore, as used herein, the term “by” may also mean “from”, depending on the context. Furthermore, as used herein, the term “if” may also mean “when” or “upon”, depending on the context. Furthermore, as used herein, the words “and/or” may refer to and encompass any and all possible combinations of one or more of the associated listed items. [0055] Example embodiments of an optical imaging lens may comprise a first lens element, a second lens element, a third lens element, a fourth lens element, and a fifth lens element. These lens elements may be arranged in an order from an object side to an image side, and example embodiments of the lens as a whole may comprise the five lens elements with refractive power. In an example embodiment: the first lens element having positive refractive power comprises a convex object-side curved surface; the second lens element having negative refractive power comprises a concave image-side curved surface; the third lens element comprises an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a concave portion in a vicinity of a periphery of the third lens element and the image-side curved surface comprises a convex portion in a vicinity of a periphery of the third lens element; the fourth lens element comprises a convex image-side curved surface; the fifth lens element comprises an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a convex portion in a vicinity of the optical axis, the image-side curved surface comprises a concave portion in a vicinity of the optical axis. The central thickness of the second lens element the along the optical axis, T2, and the sum of all air gaps between the first lens element to the fifth lens element along the optical axis, Gaa, satisfy the relation as followed: [0000] 0.20 <T 2<0.50 (mm)  equation (1); [0000] and [0000] 0.27<( T 2 /Gaa )<0.40  equation (2); [0000] and/or [0000] 0.21 <T 2<0.47 (mm)  equation (1′); [0000] and [0000] 0.28<( T 2 /Gaa )<0.40  equation (2′); [0056] to achieve good optical characters and shortened length of the optical imaging lens. [0057] In some example embodiments, other thicknesses of lens along the optical axis and/or the ratio of which to the sum of all air gaps can be also controlled, and an example is provided with controlling a central thickness of the third lens element along the optical axis, T3, and/or controlling the ratio of T3 to Gaa to satisfy the relation: [0000] 0.20 <T 3<0.60 (mm)  equation (3); [0000] and/or [0000] 0.30<( T 3 /Gaa )<0.45  equation (4); [0000] and/or [0000] 0.25 <T 3<0.57 (mm)  equation (3′); [0000] and/or [0000] 0.31<( T 3 /Gaa )<0.45  equation (4′). [0058] Because example embodiments of the lens elements, such as aforesaid first lens element, second lens element, third lens element, fourth lens element, and fifth lens element, is preferable a lens elements made by injection-molding plastic, the thickness of the lens elements will affect the technical barrier and cost. For example, if the central thickness of the second lens element along the optical axis, T2, is less than the lower limit, 0.2 (mm), the center of the second lens element may be too thin and cause melting plastic material fail to pass the mold, and compared with currently technical level, the difficulty and cost for production in such situation are too high. It will be appreciated that the lower limits of above ranges of T2 and T3 are determined based on current technical levels. Further, the thicknesses of the first lens element, the second lens element, the third lens element, the fourth lens element, and fifth lens element affect the length of the optical imaging lens. For example, if the central thickness of the second lens element along the optical axis, T2, exceeds the upper limit, 0.5 (mm), the second lens element will be too thick and cause the length of the optical imaging lens to be too long and fail to match the request of a smaller optical imaging lens. Therefore, the upper limits of the above ranges of T2 and T3 are determined based on the preferable length of the optical imaging lens. When implementing example embodiments, more details about the convex or concave surface structure and/or the refractive power may be incorporated for one specific lens element or broadly for plural lens elements to enhance the control for the system performance and/or resolution, as illustrated in the following embodiments. It is noted that the details listed here could be incorporated in example embodiments if no inconsistency occurs. [0059] Several exemplary embodiments and associated optical data will now be provided for illustrating example embodiments of optical imaging lens with good optical characters and shortened lengths. Reference is now made to FIGS. 1-5 . FIG. 1 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a first example embodiment. FIG. 2 illustrates another example cross-sectional view of a lens element of the optical imaging lens according to an example embodiment. FIG. 3 depicts an example table of optical data of each lens element of the optical imaging lens according to an example embodiment. FIG. 4 depicts an example table of aspherical data of the optical imaging lens according to an example embodiment. FIG. 5 shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens according to an example embodiment. [0060] As shown in FIG. 1 , the optical imaging lens of the present embodiment comprises, in order from an object side A1 to an image side A2, an aperture stop 100 positioned at the object side of a first lens element 110 , the first lens element 110 , a second lens element 120 , a third lens element 130 , a fourth lens element 140 , and a fifth lens element 150 . Both of a filtering unit 160 and image plane 170 of an image sensor are positioned at the image side A2 of the optical imaging lens. The example embodiment of filtering unit 160 illustrated is an IR cut filter (infrared cut filter) positioned between the image-side curved surface 152 of the fifth lens element 150 and an image plane 170 , which filters out light with specific wavelength from the light passing optical imaging lens. For example, IR light is filtered out, and this will prohibit the IR light which is not seen by human eyes from producing an image on the image plane 170 . [0061] Exemplary embodiments of each lens elements of the optical imaging lens will now be described with reference to the drawings. [0062] An example embodiment of the first lens element 110 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 111 and a convex image-side curved surface 112 . The convex surface 111 and convex surface 112 may both be aspherical surfaces. [0063] The second lens element 120 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 121 having a concave portion 1211 in a vicinity of the optical axis, a concave portion 1212 neighboring the circumference, and a concave image-side curved surface 122 . The curved surface 121 and concave surface 122 may both be aspherical surfaces in a vicinity of the optical axis in a vicinity of the optical axis in a vicinity of a periphery of the fifth lens element 150 . [0064] The third lens element 130 may have positive refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 131 having a convex portion 1311 in a vicinity of the optical axis, and a concave portion 1312 in a vicinity of a periphery of the third lens element 130 , and an image-side curved surface 132 . The image-side curved surface 132 may comprise a concave portion 1321 in a vicinity of the optical axis and a convex portion 1322 in a vicinity of a periphery of the third lens element 130 . The curved surface 131 , 132 may both be aspherical surfaces. [0065] The fourth lens element 140 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 141 and a convex image-side curved surface 142 . The concave surface 141 and convex surface 142 may both be aspherical surfaces. [0066] The fifth lens element 150 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 151 , which may comprise a convex portion 1511 in a vicinity of the optical axis and a convex portion 1512 in a vicinity of a periphery of the fifth lens element 150 , and an image-side curved surface 152 , which may comprise a concave portion 1521 in a vicinity of the optical axis and a convex portion 1522 in a vicinity of a periphery of the fifth lens element 150 . The curved surface 151 and the curved surface 152 may both be gull wing surfaces of aspherical surfaces. [0067] In example embodiments, air gaps exist between the lens elements, the filtering unit 160 , and the image plane 170 of the image sensor. For example, FIG. 1 illustrates the air gaps d1 existing between the first lens element 110 and the second lens element 120 , the air gaps d2 existing between the second lens element 120 and the third lens element 130 , the air gaps d3 existing between the third lens element 130 and the fourth lens element 140 , the air gaps d4 existing between the fourth lens element 140 and the fifth lens element 150 , the air gaps d5 existing between fifth lens element 150 and the filtering unit 160 , and the air gaps d6 existing between the filtering unit 160 and the image plane 170 of the image sensor. However, in other embodiments, any of the aforesaid air gaps may or may not exist. For example, the profiles of opposite surfaces of any two adjacent lens elements may correspond to each other (attached together and therefore form one surface or do not form a surface at all), and in such situation, the air gaps may not exist. The sum of all air gaps d1, d2, d3, d4 between the first and fifth lens elements is denoted by Gaa. [0068] FIG. 3 depicts the optical characters of each lens elements in the optical imaging lens of the present embodiment, wherein the values of T2, T3, T2/Gaa and T3/Gaa are: [0069] T2=0.31000 (mm), satisfying equations (1), (1′); [0070] T2/Gaa=0.28999, satisfying equations (2), (2′); [0071] T3=0.34207 (mm), satisfying equations (3), (3′); [0072] T3/Gaa=0.31999, satisfying equations (4), (4′); [0073] wherein the distance from the object-side curved surface 111 of the first lens element 110 to the image-side curved surface 152 of the fifth lens element 150 is 3.75436 (mm), and the length of the optical imaging lens is shortened. [0074] Please note that, in example embodiments, to clearly illustrate the structure of each lens element, only the part where light passes, i.e. effective part, is shown. For example, taking the first lens element 110 as an example, FIG. 1 illustrates the convex object-side curved surface 111 and the convex image-side curved surface 112 . However, when implementing each lens element of the present embodiment, a non-effective part may be formed selectively. Based on the first lens element 110 , please refer to FIG. 2 , which illustrates the first lens element 110 comprising a further non-effective part. Here the non-effective part is not limited to a protruding part 113 for mounting the first lens element 110 in the optical imaging lens, and light will not pass through the protruding part 113 . [0075] As illustrated in FIG. 1 , the aspherical surfaces, including the convex surface 111 and the convex surface 112 of the first lens element 110 , the curved surface 121 and the concave surface 122 of the second lens element 120 , the curved surfaces 131 , 132 of the third lens element 130 , the concave surface 141 and the convex surface 142 of the fourth lens element 140 , and the curved surface 151 and the curved surface 152 of fifth lens element 150 , are all defined by the aspherical formula: [0000] Z  ( Y ) = Y 2 R / ( 1 + 1 - ( 1 + K )  Y 2 R 2 ) + ∑ i = 1 n  a 2  i × Y 2  i [0076] wherein: [0077] R represents the radius of the surface of the lens element; [0078] Z represents the depth of the aspherical surface (the perpendicular distance between the point of the aspherical surface at a distance Y from the optical axis and the tangent plane of the vertex on the optical axis of the aspherical surface); [0079] Y represents the perpendicular distance between the point of the aspherical surface and the optical axis; [0080] K represents a conic constant; [0081] a i represents an aspherical coefficient of i th level; [0082] and the values of each aspherical parameter are represented in FIG. 4 . [0083] As illustrated in FIGs (a) through (d), the optical imaging lens of present example embodiments show great characteristics in the longitudinal spherical aberration (a), astigmatism aberration in the sagittal direction (b), astigmatism aberration in the tangential direction (c), and/or distortion aberration (d). Therefore, according to above illustration, the optical imaging lens of example embodiments indeed achieve great optical performance and the length of the optical imaging lens is effectively shortened. [0084] Reference is now made to FIGS. 6-9 . FIG. 6 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a second example embodiment. FIG. 7 shows an example table of optical data of each lens element of the optical imaging lens according to the second example embodiment. FIG. 8 shows an example table of aspherical data of the optical imaging lens according to the second example embodiment. FIG. 9( a ) shows the longitudinal spherical aberration, FIGS. 9( b ) and 9 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 9( d ) shows the distortion of the optical imaging lens of FIG. 6 . [0085] As shown in FIG. 6 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises an aperture stop 200 positioned at the object side of a first lens element 210 , the first lens element 210 , a second lens element 220 , a third lens element 230 , a fourth lens element 240 , and a fifth lens element 250 . Both of a filtering unit 260 and an image plane 270 of an image sensor are positioned at the image side A2 of the optical imaging lens. In an example embodiment, filtering unit 260 is an IR cut filter positioned between the image-side curved surface 252 of the fifth lens element 250 and the image plane 270 to filter out light with specific wavelength from the light passing optical imaging lens. For example, IR light is filtered out, and this will prohibit the IR light which is not seen by human eyes from producing an image on image plane 270 . [0086] One difference between the second embodiments and the first embodiments is that the central thickness of lens T2 of the second lens element 220 and the central thickness of lens T3 of the third lens element 230 are different. In this regard, the sum of all air gaps Gaa from the first lens element 210 to the fifth lens element 250 may be different. Please refer to FIG. 7 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein the values of T2, T3, T2/Gaa and T3/Gaa are: [0087] T2=0.25763 (mm), satisfying equations (1), (1′); [0088] T2/Gaa=0.29805, satisfying equations (2), (2′); [0089] T3=0.27660 (mm), satisfying equations (3), (3′); [0090] T3/Gaa=0.32000, satisfying equations (4), (4′) [0091] wherein the distance from the object side of the first lens element to the image side of the fifth lens element is 3.68615 (mm) and the length of the optical imaging lens is shortened. [0092] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0093] The first lens element 210 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 211 and a convex image-side curved surface 212 . The convex surface 211 and convex surface 212 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 8 for values of the aspherical parameters. [0094] The second lens element 220 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 221 , which has a convex portion 2211 in a vicinity of the optical axis and a convex portion 2212 in a vicinity of a periphery of the second lens element 220 , and a concave image-side curved surface 222 . The curved surface 221 and concave surface 222 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 8 for values of the aspherical parameters. [0095] The third lens element 230 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 231 , which has a convex portion 2311 in a vicinity of the optical axis and a concave portion 2312 in a vicinity of a periphery of the third lens element 230 , and an image-side curved surface 232 , which has a concave portion 2321 in a vicinity of the optical axis and a convex portion 2322 in a vicinity of a periphery of the third lens element 230 . The curved surface 231 , 232 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 8 for values of the aspherical parameters. [0096] The fourth lens element 240 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 241 and a convex image-side curved surface 242 . The concave surface 241 and convex surface 242 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 8 for values of the aspherical parameters. [0097] The fifth lens element 250 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 251 , which has a convex portion 2511 in a vicinity of the optical axis and a convex portion 2512 in a vicinity of a periphery of the fifth lens element 250 , and an image-side curved surface 252 , which has a concave portion 2521 in a vicinity of the optical axis and a convex portion 2522 in a vicinity of a periphery of the fifth lens element 250 . The curved surface 251 , 252 may both be gull wing surfaces of the aspherical surfaces defined by the aspherical formula. Please refer to FIG. 8 for values of the aspherical parameters. [0098] In the present embodiment, similar to the first example embodiment, air gaps may exist between the lens elements 210 , 220 , 230 , 240 , 250 , the filtering unit 260 , and the image plane 270 of the image sensor. Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa. [0099] As shown in FIG. 9 , the optical imaging lens of the present embodiment shows great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d). Therefore, according to the above illustration, the optical imaging lens of the present embodiment indeed shows great optical performance and the length of the optical imaging lens is effectively shortened. [0100] Reference is now made to FIGS. 10-13 . FIG. 10 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a third example embodiment. FIG. 11 depicts an example table of optical data of each lens element of the optical imaging lens according to the third example embodiment. FIG. 12 depicts an example table of aspherical data of the optical imaging lens according to the third example embodiment. FIG. 13 shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens according to the third example embodiment. [0101] As shown in FIG. 10 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises a first lens element 310 , an aperture stop 300 positioned between the first lens element 310 and a second lens element 320 , the second lens element 320 , a third lens element 330 , a fourth lens element 340 , and a fifth lens element 350 . Both of a filtering unit 360 and an image plane 370 of an image sensor may be positioned at the image side A2 of the optical imaging lens. Here an example embodiment of the filtering unit 360 is an IR cut filter positioned between the image-side curved surface 352 of the fifth lens element 350 and the image plane 370 to filter out light with specific wavelength from the light passing optical imaging lens. For example, the IR light is filtered out, and this will prohibit the IR light which is not seen by human eyes from producing an image on image plane 370 . [0102] Please refer to FIG. 11 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein the values of T2, T3, T2/Gaa and T3/Gaa are: [0103] T2=0.25285 (mm), satisfying equations (1), (1′); [0104] T2/Gaa=0.31316, satisfying equations (2), (2′); [0105] T3=0.27452 (mm), satisfying equations (3), (3′); [0106] T3/Gaa=0.34000, satisfying equations (4), (4′); [0107] wherein the distance from the object side of the first lens element 310 to the image side of the fifth lens element 350 is 3.81589 (mm), and the length of the optical imaging lens is shortened. [0108] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0109] The first lens element 310 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 311 and a concave image-side curved surface 312 . The convex surface 311 and concave surface 312 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 12 for values of the aspherical parameters. [0110] The aperture stop 300 may be positioned between the first lens element 310 and the second lens element 320 . [0111] The second lens element 320 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 321 , which has a convex portion 3211 in a vicinity of the optical axis and a convex portion 3212 in a vicinity of a periphery of the second lens element 320 , and a concave image-side curved surface 322 . The curved surface 321 and concave surface 322 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 12 for values of the aspherical parameters. [0112] The third lens element 330 may have positive refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 331 , which has a convex portion 3311 in a vicinity of the optical axis and a concave portion 3312 in a vicinity of a periphery of the third lens element 330 , and an image-side curved surface 332 , which has a concave portion 3321 in a vicinity of the optical axis and a convex portion 3322 in a vicinity of a periphery of the third lens element 330 . The curved surface 331 , 332 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 12 for values of the aspherical parameters. [0113] The fourth lens element 340 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 341 and a convex image-side curved surface 342 . The concave surface 341 and convex surface 342 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 12 for values of the aspherical parameters. [0114] The fifth lens element 350 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 351 , which has a convex portion 3511 in a vicinity of the optical axis and a convex portion 3512 in a vicinity of a periphery of the fifth lens element 350 , and an image-side curved surface 352 , which has a concave portion 3521 in a vicinity of the optical axis and a convex portion 3522 in a vicinity of a periphery of the fifth lens element 350 . The curved surface 351 , 352 may both be gull wing surfaces of aspherical surfaces defined by the aspherical formula. Please refer to FIG. 12 for values of the aspherical parameters. [0115] In the present embodiment, for comparison, similar to the first embodiment, air gaps may exist between the lens elements 310 , 320 , 330 , 340 , 350 , the filtering unit 360 , and the image plane 370 of the image sensor. Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa. [0116] One difference between the third embodiment and the first embodiment is that the central thickness of lens T2 of the second lens element 320 and the central thickness of lens T3 of the third lens element 330 are different. In this regard, the sum of all air gaps Gaa from the first lens element 310 to the fifth lens element 350 may be different. Further, the aperture stop 300 of the present embodiment may be positioned between the first lens element 310 and the second lens element 320 , which may be different from the position of the aperture stop 100 in front of the first lens element 110 in the first embodiment. [0117] As illustrated in FIG. 13 , it is clear that the optical imaging lens of the present embodiment may achieve great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d). Therefore, according to above illustration, the optical imaging lens of the present embodiment indeed achieve great optical performance, and the length of the optical imaging lens is effectively shortened. [0118] Reference is now made to FIGS. 14-17 . FIG. 14 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a fourth example embodiment. FIG. 15 shows an example table of optical data of each lens element of the optical imaging lens according to the fourth example embodiment. FIG. 16 shows an example table of aspherical data of the optical imaging lens according to the fourth example embodiment. FIG. 17 shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens according to the fourth example embodiment. [0119] As shown in FIG. 14 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises an aperture stop 400 positioned at the object side of a first lens element 410 , the first lens element 410 , a second lens element 420 , a third lens element 430 , a fourth lens element 440 , and a fifth lens element 450 . Both of a filtering unit 460 and an image plane 470 of an image sensor may be positioned at the image side A2 of the optical imaging lens. Here an example embodiment of filtering unit 460 is an IR cut filter, which may be positioned between the image-side curved surface 452 of the fifth lens element 450 and the image plane 470 to filter out light with specific wavelength from the light passing optical imaging lens. For example, IR light may be filtered out, and this will prohibit the IR light which is not seen by human eyes from producing an image on image plane 470 . [0120] Please refer to FIG. 15 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein The values of T2, T3, T2/Gaa and T3/Gaa are: [0121] T2=0.45000 (mm), satisfying equations (1), (1′); [0122] T2/Gaa=0.39001, satisfying equations (2), (2′); [0123] T3=0.36920 (mm), satisfying equations (3), (3′); [0124] T3/Gaa=0.31998, satisfying equations (4), (4′); [0125] wherein the distance from the object side of the first lens element to the image side of the fifth lens element is 3.71940 (mm), and the length of the optical imaging lens is shortened. [0126] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0127] The first lens element 410 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 411 and a concave image-side curved surface 412 . The convex surface 411 and the concave surface 412 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 16 for values of the aspherical parameters. [0128] The second lens element 420 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 421 , which has a convex portion 4211 in a vicinity of the optical axis and a concave portion 4212 in a vicinity of a periphery of the second lens element 420 , and a concave image-side curved surface 422 . The curved surface 421 and concave surface 422 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 16 for values of the aspherical parameters. [0129] The third lens element 430 may have positive refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 431 , which has a convex portion 4311 in a vicinity of the optical axis and a concave portion 4312 in a vicinity of a periphery of the third lens element 430 , and an image-side curved surface 432 , which has a concave portion 4321 in a vicinity of the optical axis and a convex portion 4322 in a vicinity of a periphery of the third lens element 430 . The curved surface 431 , 432 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 16 for values of the aspherical parameters. [0130] The fourth lens element 440 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 441 and a convex image-side curved surface 442 . The concave surface 441 and convex surface 442 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 16 for values of the aspherical parameters. [0131] The fifth lens element 450 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 451 , which has a convex portion 4511 in a vicinity of the optical axis and a convex portion 4512 in a vicinity of a periphery of the fifth lens element 450 , and an image-side curved surface 452 , which has a concave portion 4521 in a vicinity of the optical axis and a convex portion 4522 in a vicinity of a periphery of the fifth lens element 450 . The curved surface 451 , 452 may both be gull wing surfaces of aspherical surfaces defined by the aspherical formula. Please refer to FIG. 16 for values of the aspherical parameters. [0132] In the present embodiment, for comparison, similar to the first embodiment, air gaps may exist between the lens elements 410 , 420 , 430 , 440 , 450 , the filtering unit 460 , and the image plane 470 of the image sensor. Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa. [0133] One difference between the fourth embodiment and the first embodiment is that the central thickness of lens T2 of the second lens element 420 and the central thickness of lens T3 of the third lens element 430 may be different. In this regard, the sum of all air gaps Gaa from the first lens element 410 to the fifth lens element 450 may be different. [0134] As illustrated in FIG. 17 , it is clear that the optical imaging lens of the present embodiment may achieve great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d). Therefore, according to above illustration, the optical imaging lens of the present embodiment indeed achieves great optical performance, and the length of the optical imaging lens is effectively shortened. [0135] Reference is now made to FIGS. 18-21 . FIG. 18 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a fifth embodiment. FIG. 19 shows an example table of optical data of each lens element of the optical imaging lens according to the fifth example embodiment. FIG. 20 shows an example table of aspherical data of the optical imaging lens according to the fifth example embodiment. FIG. 21 shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens according to the fifth example embodiment. [0136] As shown in FIG. 18 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises an aperture stop 500 positioned between the object side and a first lens element 510 , the first lens element 510 , a second lens element 520 , a third lens element 530 , a fourth lens element 540 , and a fifth lens element 550 . Both of a filtering unit 560 and an image plane 570 of an image sensor may be positioned at the image side A2 of the optical imaging lens. Here an example embodiment of filtering unit 560 is an IR cut filter, which may be positioned between the image-side curved surface 552 of the fifth lens element 550 and the image plane 570 to filter out light with specific wavelength from the light passing optical imaging lens. For example, IR light may be filtered out, and this will prohibit the IR light which is not seen by human eyes from producing an image on image plane 570 . [0137] Please refer to FIG. 19 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein The values of T2, T3, T2/Gaa and T3/Gaa are: [0138] T2=0.29660 (mm), satisfying equations (1), (1′); [0139] T2/Gaa=0.29001, satisfying equations (2), (2′); [0140] T3=0.45000 (mm), satisfying equations (3), (3′); [0141] T3/Gaa=0.44001, satisfying equations (4), (4′); [0142] wherein the distance from the object side of the first lens element to the image side of the fifth lens element is 3.70690 (mm), and the length of the optical imaging lens is shortened. [0143] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0144] The first lens element 510 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 511 and a concave image-side curved surface 512 . The convex surface 511 and concave surface 512 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 20 for values of the aspherical parameters. [0145] The second lens element 520 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 521 , which has a convex portion 5211 in a vicinity of the optical axis and a convex portion 5212 in a vicinity of a periphery of the second lens element 520 , and a concave image-side curved surface 522 . The curved surface 521 and concave surface 522 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 20 for values of the aspherical parameters. [0146] The third lens element 530 may have positive refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 531 , which has a concave portion 5311 in a vicinity of the optical axis and a concave portion 5312 in a vicinity of a periphery of the third lens element 530 , and an image-side curved surface 532 , which has a convex portion 5321 in a vicinity of the optical axis and a convex portion 5322 in a vicinity of a periphery of the third lens element 530 . The curved surface 531 , 532 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 20 for values of the aspherical parameters. [0147] The fourth lens element 540 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 541 and a convex image-side curved surface 542 . The concave surface 541 and convex surface 542 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 20 for values of the aspherical parameters. [0148] The fifth lens element 550 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 551 , which has a convex portion 5511 in a vicinity of the optical axis and a convex portion 5512 in a vicinity of a periphery of the fifth lens element 550 , and an image-side curved surface 552 , which has a concave portion 5521 in a vicinity of the optical axis and a convex portion 5522 in a vicinity of a periphery of the fifth lens element 550 . The curved surfaces 551 , 552 may both be gull wing surfaces of aspherical surfaces defined by the aspherical formula. Please refer to FIG. 20 for values of the aspherical parameters. [0149] In the present embodiment, for comparison, similar to the first embodiment, air gaps may exist between the lens elements 510 , 520 , 530 , 540 , 550 , the filtering unit 560 , and the image plane 570 of the image sensor. Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa. [0150] One difference between the fifth embodiment and the first embodiment is that the central thickness of lens T2 of the second lens element 520 and the central thickness of lens T3 of the third lens element 530 may be different. Therefore, the sum of all air gaps Gaa from the first lens element 510 to the fifth lens element 550 may be different. [0151] As illustrated in FIG. 21 , it is clear that the optical imaging lens of the present embodiment may show great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d). Therefore, according to above illustration, the optical imaging lens of the present embodiment indeed achieves great optical performance, and the length of the optical imaging lens is effectively shortened. [0152] Reference is now made to FIGS. 22-25 . FIG. 22 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a sixth example embodiment. FIG. 23 shows an example table of optical data of each lens element of the optical imaging lens according to the sixth example embodiment. FIG. 24 shows an example table of aspherical data of the optical imaging lens according to the sixth example embodiment. FIG. 25( a ) shows the longitudinal spherical aberration, FIGS. 25( b ) and 25 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 25( d ) shows the distortion according to the sixth example embodiment. [0153] As shown in FIG. 22 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises an aperture stop 600 positioned between the object side and a first lens element 610 , the first lens element 610 , a second lens element 620 , a third lens element 630 , a fourth lens element 640 , and a fifth lens element 650 . Both of a filtering unit 660 and an image plane 670 of an image sensor may be positioned at the image side A2 of the optical imaging lens. Here an example embodiment of filtering unit 660 may be an IR cut filter, which may be positioned between the image-side curved surface 652 of the fifth lens element 650 and the image plane 670 to filter out light with specific wavelength from the light passing optical imaging lens. For example, IR light may be filtered out, and this may prohibit the IR light which is not seen by human eyes from producing an image on image plane 670 . [0154] Please refer to FIG. 23 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein The values of T2, T3, T2/Gaa and T3/Gaa are: [0155] T2=0.36250 (mm), satisfying equations (1), (1′); [0156] T2/Gaa=0.29000, satisfying equations (2), (2′); [0157] T3=0.55000 (mm), satisfying equations (3), (3′); [0158] T3/Gaa=0.44000, satisfying equations (4), (4′); [0159] wherein the distance from the object side of the first lens element to the image side of the fifth lens element is 3.84120 (mm), and the length of the optical imaging lens is shortened. [0160] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0161] The first lens element 610 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 611 and a concave image-side curved surface 612 . The convex surface 611 and 612 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 24 for values of the aspherical parameters. [0162] The second lens element 620 may have negative refractive power, which may be constructed by plastic material, and may be an object-side curved surface 621 , which has a convex portion 6211 in a vicinity of the optical axis and a convex portion 6212 in a vicinity of a periphery of the second lens element 620 , and a concave image-side curved surface 622 . The curved surface 621 and concave surface 622 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 24 for values of the aspherical parameters. [0163] The third lens element 630 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 631 , which has a concave portion 6311 in a vicinity of the optical axis and a concave portion 6312 in a vicinity of a periphery of the third lens element 630 , and an image-side curved surface 632 , which has a concave portion 6321 in a vicinity of the optical axis and a convex portion 6322 in a vicinity of a periphery of the third lens element 630 . The curved surface 631 , 632 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 24 for values of the aspherical parameters. [0164] The fourth lens element 640 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 641 and a convex image-side curved surface 642 . The concave surface 641 and convex surface 642 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 24 for values of the aspherical parameters. [0165] The fifth lens element 650 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 651 , which has a convex portion 6511 in a vicinity of the optical axis and a convex portion 6512 in a vicinity of a periphery of the fifth lens element 650 , and an image-side curved surface 652 , which has a concave portion 6521 in a vicinity of the optical axis and a convex portion 6522 in a vicinity of a periphery of the fifth lens element 650 . The curved surface 651 , 652 may both be gull wing surfaces of aspherical surfaces defined by the aspherical formula. Please refer to FIG. 24 for values of the aspherical parameters. [0166] In the present embodiment, for comparison, similar to the first embodiment, air gaps may exist between the lens elements 610 , 620 , 630 , 640 , 650 , the filtering unit 660 , and the image plane 670 of the image sensor. Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa. [0167] One difference between the sixth embodiment and the first embodiment is that the central thickness of lens T2 of the second lens element 620 and the central thickness of lens T3 of the third lens element 630 may be different. In this regard, the sum of all air gaps Gaa from the first lens element 610 to the fifth lens element 650 may be different. [0168] As illustrated in FIG. 25 , it is clear that the optical imaging lens of the present embodiment may show great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d). Therefore, according to above illustration, the optical imaging lens of the present embodiment indeed achieves great optical performance, and the length of the optical imaging lens is effectively shortened. [0169] Reference is now made to FIGS. 26-29 . FIG. 26 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a seventh example embodiment. FIG. 27 shows an example table of optical data of each lens element of the optical imaging lens according to the seventh example embodiment. FIG. 28 shows an example table of aspherical data of the optical imaging lens according to the seventh example embodiment. FIG. 29 shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens according to the seventh example embodiment. [0170] As shown in FIG. 26 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises an aperture stop 700 positioned between the object side and a first lens element 710 , the first lens element 710 , a second lens element 720 , a third lens element 730 , a fourth lens element 740 , and a fifth lens element 750 . Both of a filtering unit 760 and an image plane 770 of an image sensor may be positioned at the image side A2 of the optical imaging lens. Here an example embodiment of filtering unit 760 may comprise an IR cut filter, which is positioned between the image-side curved surface 752 of the fifth lens element 750 and the image plane 770 to filter out light with specific wavelength from the light passing optical imaging lens. For example, IR light is filtered out, and this may prohibit the IR light which is not seen by human eyes from producing an image on image plane 770 . [0171] Please refer to FIG. 27 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein The values of T2, T3, T2/Gaa and T3/Gaa are: [0172] T2=0.21999 (mm), satisfying equations (1), (1′); [0173] T2/Gaa=0.28974, satisfying equations (2), (2′); [0174] T3=0.26816 (mm), satisfying equations (3), (3′); [0175] T3/Gaa=0.35319, satisfying equations (4), (4′); [0176] wherein the distance from the object side of the first lens element to the image side of the fifth lens element is 3.59439 (mm), and the length of the optical imaging lens is shortened. [0177] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0178] The first lens element 710 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 711 and a concave image-side curved surface 712 . The surfaces 711 and 712 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 28 for values of the aspherical parameters. [0179] The second lens element 720 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 721 , which has a convex portion 7211 in a vicinity of the optical axis and a convex portion 7212 in a vicinity of a periphery of the second lens element 720 , and a concave image-side curved surface 722 . The curved surface 721 and concave surface 722 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 28 for values of the aspherical parameters. [0180] The third lens element 730 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 731 , which has a concave portion 7311 in a vicinity of the optical axis and a concave portion 7312 in a vicinity of a periphery of the third lens element 730 , and an image-side curved surface 732 , which has a convex portion 7321 in a vicinity of the optical axis and a convex portion 7322 in a vicinity of a periphery of the third lens element 730 . The curved surfaces 731 , 732 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 28 for values of the aspherical parameters. [0181] The fourth lens element 740 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 741 and a convex image-side curved surface 742 . The concave surface 741 and convex surface 742 may both be aspherical surfaces defined by the aspherical formula. Please refer to FIG. 28 for values of the aspherical parameters. [0182] The fifth lens element 750 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 751 , which has a convex portion 7511 in a vicinity of the optical axis and a convex portion 7512 in a vicinity of a periphery of the fifth lens element 750 , and an image-side curved surface 752 , which has a concave portion 7521 in a vicinity of the optical axis and a convex portion 7522 in a vicinity of a periphery of the fifth lens element 750 . The curved surfaces 751 , 752 may both be gull wing surfaces of aspherical surfaces defined by the aspherical formula. Please refer to FIG. 28 for values of the aspherical parameters. [0183] In the present embodiment, for comparison, similar to the first embodiment, air gaps may exist between the lens elements 710 , 720 , 730 , 740 , 750 , the filtering unit 760 , and the image plane 770 of the image sensor. Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa. [0184] One difference between the seventh embodiment and the first embodiment is the central thickness of lens T2 of the second lens element 720 and the central thickness of lens T3 of the third lens element 730 may be different. In this regard, the sum of all air gaps Gaa from the first lens element 710 to the fifth lens element 750 may be different. [0185] As illustrated in FIG. 29 , it is clear that the optical imaging lens of the present embodiment may show great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d). Therefore, according to above illustration, the optical imaging lens of the present embodiment indeed achieves great optical performance, and the length of the optical imaging lens is effectively shortened. [0186] Please refer to FIG. 30 , which shows the values of T2, T3, T2/Gaa and T3/Gaa of all seven embodiments. As shown, this table provides a clear illustration that the optical imaging lens of example embodiments indeed satisfies the equations (1), (2), (3), (4), (1′), (2′), (3′), and (4′). [0187] Reference is now made to FIGS. 31-32 . FIG. 31 illustrates an example structural view of an example embodiment of mobile device 1 . FIG. 32 shows an example enlarged view of the example embodiment of mobile device 1 of FIG. 31 . An example of the mobile device 1 may be a mobile phone, but the type of the mobile device 1 should not be limited to such. As shown, the mobile device 1 may comprise a housing 10 and an optical imaging lens assembly 20 positioned in the housing 10 . The housing 10 protects the optical imaging lens assembly 20 therein, and is not limited to any shape or material. The optical imaging lens assembly 20 may comprise a lens barrel 21 , an optical imaging lens 22 , a module housing unit 23 , and an image sensor 171 which is positioned at an image side of the optical imaging lens 22 . In example embodiments, any optical imaging lens may be used as the optical imaging lens 22 , such as any optical imaging lens disclosed in the aforesaid embodiments or other optical imaging lens according to example embodiments. However, for clearly illustrating the present embodiment, the optical imaging lens of the first embodiment will be used as the optical imaging lens 22 . When using other optical imaging lens 22 , the structure of the filtering unit 160 may be omitted. Furthermore, the housing 10 , the lens barrel 21 , and/or the module housing unit 23 may be integrated into a single component or assembled by multiple components. Furthermore, the image sensor 171 used in the present embodiment is directly attached on the substrate 172 in the form of a chip on board (COB) package, and such package is different from traditional chip scale packages (CSP) since it does not require a cover glass. That is, no cover glass is required before the image sensor 171 in the optical imaging lens 22 . It should be noted, however, that example embodiments are not limited to this package type. The optical imaging lens with refractive power as a whole comprises five lens elements 110 , 120 , 130 , 140 , 150 positioned in the lens barrel 21 , wherein an air gap may exist between any two adjacent lens elements. The module housing unit 23 is provided for positioning the optical imaging lens 22 thereon, and preferably comprises an image sensor base 233 and an auto focus module 234 . The image sensor base 233 may be fixed on the substrate 172 , and the auto focus module 234 may comprise a lens seat 2341 for positioning the optical imaging lens 22 . The lens seat 2341 may be capable of moving back and forth along the optical axis to control the focusing of the optical imaging lens 22 . For example, according to the distance of the object, the optical imaging lens 22 may be moved back and forth until the image focuses on the image plane 170 of the image sensor 171 . Because the length of the optical imaging lens 22 is merely 3.75436 (mm), the size of the mobile device 1 may be quite small with good optical characters. Therefore, the present embodiment meets the demand of smaller sized product design and the request of the market. [0188] Reference is now made to FIG. 33 , which shows a structural view of an example embodiment of mobile device 2 . Here the housing is not shown, and only the optical imaging lens assembly 20 is shown. As shown, one difference between the mobile device 2 and the mobile device 1 may be the structure of the module housing unit 24 . The module housing unit 24 may comprise an image sensor base 243 and an auto focus module 244 , which may comprise a voice coil motor (VCM) comprising a lens seat 2441 , a magnet 2442 and a coil 2443 . With the magnetic force produced by the magnet 2442 and the coil 2443 , the VCM may move the lens seat 2441 slightly to move the lens seat 2441 back and forth along an optical axis to focus the optical imaging lens 22 . Because the length of the optical imaging lens 22 may be shortened, the mobile device 2 may be designed with a smaller size and meanwhile good optical performance is still provided. Therefore, the present embodiment meets the demand of small sized product design and the request of the market. [0189] According to above illustration, it is clear that the mobile device and the optical imaging lens thereof in example embodiments, through controlling ratio of at least one central thickness of lens to a sum of all air gaps along the optical axis between five lens elements in a predetermined range, and incorporated with detail structure and/or reflection power of the lens elements, the lengths of the optical imaging lens is effectively shortened and meanwhile good optical characters are still provided. [0190] While various embodiments in accordance with the disclosed principles have been described above, it should be understood that they have been presented by way of example only, and are not limiting. Thus, the breadth and scope of exemplary embodiment(s) should not be limited by any of the above-described embodiments, but should be defined only in accordance with the claims and their equivalents issuing from this disclosure. Furthermore, the above advantages and features are provided in described embodiments, but shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages. [0191] Additionally, the section headings herein are provided for consistency with the suggestions under 37 C.F.R. 1.77 or otherwise to provide organizational cues. These headings shall not limit or characterize the invention(s) set out in any claims that may issue from this disclosure. Specifically, a description of a technology in the “Background” is not to be construed as an admission that technology is prior art to any invention(s) in this disclosure. Furthermore, any reference in this disclosure to “invention” in the singular should not be used to argue that there is only a single point of novelty in this disclosure. Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s), and their equivalents, that are protected thereby. In all instances, the scope of such claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings herein.
Present embodiments provide for a mobile device and an optical imaging lens thereof. The optical imaging lens comprises five lens elements positioned in an order from an object side to an image side. Through controlling the convex or concave shape of the surfaces of the lens elements to allow the thickness of the second lens element and the sum of all air gaps between all five lens elements along the optical axis satisfying the relation: 0.20<T2<0.50 (mm) and 0.27<(T2/G aa )<0.40, the optical imaging lens shows better optical characteristics and the total length of the optical imaging lens is shortened.
Identify and summarize the most critical technical features from the given patent document.
[ "CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser.", "No. 13/617,231, filed on Sep. 14, 2012, entitled “Mobile Device and Optical Imaging Lens Thereof”", "which claims priority from Taiwan Patent Application No. 101111443, filed on Mar. 30, 2012, the disclosures of which are hereby incorporated by reference in their entirety for all purposes.", "TECHNICAL FIELD [0002] The present invention relates to a mobile device and an optical imaging lens thereof, and particularly, relates to a mobile device applying an optical imaging lens having five lens elements and an optical imaging lens thereof.", "BACKGROUND OF THE INVENTION [0003] The ever-increasing demand for smaller sized mobile devices, such as cell phones, digital cameras, etc.", "has correspondingly triggered a growing need for smaller sized photography modules contained therein.", "Size reductions may be contributed from various aspects of the mobile devices, which includes not only the charge coupled device (CCD) and the complementary metal-oxide semiconductor (CMOS), but also the optical imaging lens mounted therein.", "When reducing the size of the optical imaging lens, however, achieveing good optical characteristics becomes a challenging problem.", "[0004] US Patent Publication No. 20100253829, US Patent Publication No. 2011013069, US Patent Publication No. 20110249346, US Patent Publication No. 20100254029, U.S. Pat. No. 7,826,151, U.S. Pat. No. 7,864,454, U.S. Pat. No. 7,911,711, U.S. Pat. No. 8,072,695, Taiwan Patent No. M368072, Taiwan Patent No. M369460 and Taiwan Patent No. M369459 all disclosed an optical imaging lens constructed with an optical imaging lens having five lens elements.", "Those disclosed optical imaging lenses involved use of a shortened length of the optical imaging lens;", "however, some of lengths of the optical imaging lens remained too long.", "For example, in the first embodiment of Taiwan Patent No. M368072, the length of the optical imaging lens is around 5.61 mm, which is not beneficial for the smaller design of mobile devices.", "[0005] How to effectively shorten the lengths of the optical imaging lens is one of the most important topics in the industry to peruse the trend of smaller and smaller mobile devices.", "Each of the aforesaid patent documents faces the limitation of the size of the mobile device due to the problem of reducing length of the optical imaging lens.", "Therefore, there is needed to develop optical imaging lens with shorter lengths, while also having good optical characters.", "SUMMARY OF THE INVENTION [0006] An object of the present invention is to provide a mobile device and an optical imaging lens thereof.", "With controlling the convex or concave shape of the surfaces of the lens elements, the central thickness along the optical axis, and the air gap between two lens elements, etc.", ", the lengths of the optical imaging lens is shortened and meanwhile the good optical characters, such as high resolution and the system performance, are sustained.", "[0007] In an exemplary embodiment, an optical imaging lens comprises, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, and a fifth lens element.", "The first lens element has positive refractive power and comprises a convex object-side curved surface.", "The second lens element has negative refractive power and comprises a concave image-side curved surface.", "The third lens element comprises an object-side curved surface and an image-side curved surface, and the object-side curved surface comprises a concave portion in a vicinity of a periphery of said third lens element and the image-side curved surface comprises a convex portion in a vicinity of a periphery of the third lens element.", "The fourth lens element comprises a convex image-side curved surface and the fifth lens element comprises an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a convex portion in a vicinity of the optical axis and the image-side curved surface comprises a concave portion in a vicinity of the optical axis.", "Lens as a whole has only the five lens elements with refractive power, wherein a central thickness of the second lens element along the optical axis is T2, a sum of all air gaps from the first lens element to the fifth lens element along the optical axis is Gaa, and they satisfy the relation: [0000] 0.20 <T 2<0.50 (mm);", "and [0000] 0.27<( T 2 /Gaa )<0.40.", "[0008] In another exemplary embodiment, other central thickness of lens element along the optical axis and/or other ratio of the central thickness of lens element along the optical axis to the sum of all air gaps could be further controlled, and an example among them is controlling the relation of a central thickness of the third lens element along the optical axis, T3, and the sum of all air gaps from the first lens element to the fifth lens element along the optical axis, Gaa, to satisfy the relation: [0000] 0.30<( T 3 /Gaa )<0.45.", "[0009] Another example embodiment comprises controlling T3 to further satisfy the relation: [0000] 0.20 <T 3<0.60 (mm).", "[0010] Yet, another example embodiment comprises controlling T2 and Gaa to further satisfy the relation: [0000] 0.21 <T 2<0.47 (mm);", "and [0000] 0.28<( T 2 /Gaa )<0.40.", "[0011] Yet, another example embodiment comprises controlling T3 and Gaa to further satisfy the relation: [0000] 0.25 <T 3<0.57 (mm);", "and [0000] 0.31<( T 3 /Gaa )<0.45.", "[0012] Aforesaid exemplary embodiments are not limited and could be selectively incorporated in other embodiments described herein.", "[0013] Lens elements in example embodiments, such as the aforesaid first lens element, second lens element, third lens element, fourth lens element, and fifth lens element, are preferable made by plastic lens element with injection molding.", "Therefore, the technical barrier and the cost may be affected by the thickness of lens element.", "For example, if the central thickness of the second lens element along the optical axis, T2, is less than the lower limit, 0.2 (mm), the center of the second lens element may be too thin and cause melting plastic material to fail to pass the mold, and compared with currently technical level, the difficulty and cost for production in such situations are too high.", "Therefore, the lower limits of the above ranges of T2 and T3 are determined based on currently technical level.", "Further, the thicknesses of the first lens element, the second lens element, the third lens element, the fourth lens element, and fifth lens element affect the length of the optical imaging lens.", "For example, if the central thickness of the second lens element along the optical axis, T2, exceeds the upper limit, 0.5 (mm), the second lens element may be too thick and cause the length of the optical imaging lens to be too long and fail to match the request of smaller optical imaging lens.", "Therefore, the upper limits of above ranges of T2 and T3 are determined based on the preferable length of the optical imaging lens.", "[0014] In example embodiments, an aperture stop is provided for adjusting the input of light of the system.", "For example, the aperture stop is selectively provided but not limited to be positioned at the object side of the first lens element, or positioned between the first lens element and the second lens element.", "[0015] In some exemplary embodiments, more details about the convex or concave surface structure and/or the refractive power could be incorporated for one specific lens element or broadly for plural lens elements to enhance the control for the system performance and/or resolution.", "For example, for the second lens element, an object-side curved surface is comprised, but the object-side curved surface need not be limited to a convex portion in a vicinity of a periphery of the second lens element.", "An example for illustrating the details broadly for plural lens elements comprises the first lens element having positive refractive power and comprising a convex object-side curved surface;", "the second lens element having negative refractive power and comprising an object-side curved surface and a concave image-side curved surface;", "the third lens element comprising an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a convex portion in a vicinity of the optical axis and a concave portion in a vicinity of a periphery of the third lens element, and the image-side curved surface comprises a concave portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the third lens element;", "the fourth lens element having positive refractive power and comprising a concave object-side curved surface and a convex image-side curved surface;", "and the fifth lens element having negative refractive power and comprising an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the fourth lens element, and the image-side curved surface comprises a concave portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the fourth lens element.", "Another example for illustrating the details broadly for plural lens elements comprises the first lens element having positive refractive power and comprising a convex object-side curved surface and a concave image-side curved surface;", "the second lens element having negative refractive power and comprising an object-side curved surface and a concave image-side curved surface, wherein the object-side curved surface of the second lens element comprises a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the second lens element;", "the third lens element comprising an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a concave portion in a vicinity of the optical axis and a concave portion in a vicinity of a periphery of the third lens element, and the image-side curved surface comprises a convex portion in a vicinity of a periphery of the third lens element;", "the fourth lens element having positive refractive power and comprising a concave object-side curved surface and a convex image-side curved surface;", "and the fifth lens element having negative refractive power and comprising an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the fifth lens element, and the image-side curved surface comprises a concave portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the fifth lens element.", "Exemplary embodiments for incorporating details broadly for plural lens elements are not limited to the above examples.", "[0016] Further, exemplary embodiments could provide more details about the structure, the refractive power, and/or the aperture stop position for a specific lens element or broadly for plural lens elements to fit variable requests.", "For example, based on the aforesaid examples, an example embodiment comprises the first lens element comprising a convex image-side curved surface, wherein the object-side curved surface of the second lens element comprises a concave portion in a vicinity of the optical axis and a concave portion in a vicinity of a periphery of the second lens element, the third lens element having positive refractive power, and an aperture stop provided at the object side of the first lens element.", "Another example embodiment is provided with the first lens element comprising a convex image-side curved surface, wherein the object-side curved surface of the second lens element comprises a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the second lens element, the third lens element having negative refractive power, and an aperture stop provided at the object side of the first lens element.", "Another example embodiment is provided with the first lens element comprising a concave image-side curved surface, the object-side curved surface of the second lens element comprising a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the second lens element, the third lens element having positive refractive power, and an aperture stop provided between the first lens element and the second lens element.", "Another example embodiment is provided with the first lens element comprising a concave image-side curved surface, the object-side curved surface of the second lens element comprises a convex portion in a vicinity of the optical axis and a concave portion in a vicinity of a periphery of the second lens element, the third lens element having positive refractive power, and an aperture stop provided at the object side of the first lens element.", "Similarly, based on the later of the aforesaid examples, more examples could be obtained with the further details listed below, including an example embodiment is provided with the third lens element having positive refractive power, and the third lens element the image-side curved surface comprising a convex portion in a vicinity of the optical axis.", "Another example embodiment is provided with the third lens element having negative refractive power, and the image-side curved surface of the third lens element comprising a concave portion in a vicinity of the optical axis.", "Another example embodiment is provided with the third lens element having negative refractive power, and the image-side curved surface of the third lens element comprising a convex portion in a vicinity of the optical axis.", "It is noted that the examples above may be incorporated into other embodiments if no inconsistencies arise.", "[0017] In another exemplary embodiment, a mobile device comprises a housing and an optical imaging lens assembly positioned in the housing.", "The optical imaging lens assembly comprises a lens barrel, any of aforesaid example embodiments of optical imaging lens, a module housing unit, and an image sensor.", "The lens comprising five lens elements with refractive power as a whole is positioned in the lens barrel, the module housing unit is for positioning the optical imaging lens, and the image sensor is positioned at the image-side of the optical imaging lens.", "[0018] In exemplary embodiments, the module housing unit comprises, but is not limited to, an image sensor base and an auto focus module, wherein the image sensor base is for fixing the image sensor, and the auto focus module comprises a lens seat for positioning the optical imaging lens to control the focusing of the optical imaging lens.", "[0019] Through controlling the ratio of at least one central thickness of lens element along the optical axis to a sum of all air gaps between the five lens elements along the optical axis in a predetermined range, and incorporated with the arrangement of the convex or concave shape of the surfaces of the lens element(s) and/or refraction power, the mobile device and the optical imaging lens thereof in exemplary embodiments achieve good optical characters and effectively shorten the lengths of the optical imaging lens.", "BRIEF DESCRIPTION OF THE DRAWINGS [0020] Exemplary embodiments will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: [0021] FIG. 1 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment;", "[0022] FIG. 2 shows another cross-sectional view of a lens element of the optical imaging lens according to an example embodiment;", "[0023] FIG. 3 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment;", "[0024] FIG. 4 shows a table of aspherical data of the optical imaging lens according to an example embodiment;", "[0025] FIG. 5( a ) shows the longitudinal spherical aberration, FIGS. 5( b ) and 5 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 5( d ) shows the distortion of the optical imaging lens of FIG. 1 ;", "[0026] FIG. 6 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment;", "[0027] FIG. 7 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment;", "[0028] FIG. 8 shows a table of aspherical data of the optical imaging lens according to an example embodiment;", "[0029] FIG. 9( a ) shows the longitudinal spherical aberration, FIGS. 9( b ) and 9 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 9( d ) shows the distortion of the optical imaging lens of FIG. 6 ;", "[0030] FIG. 10 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment;", "[0031] FIG. 11 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment;", "[0032] FIG. 12 shows a table of aspherical data of the optical imaging lens according to an example embodiment;", "[0033] FIG. 13( a ) shows the longitudinal spherical aberration, FIGS. 13( b ) and 13 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 13( d ) shows the distortion of the optical imaging lens of FIG. 10 ;", "[0034] FIG. 14 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment;", "[0035] FIG. 15 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment;", "[0036] FIG. 16 shows a table of aspherical data of the optical imaging lens according to an example embodiment;", "[0037] FIG. 17( a ) shows the longitudinal spherical aberration, FIGS. 17( b ) and 17 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 17( d ) shows the distortion of the optical imaging lens of FIG. 14 ;", "[0038] FIG. 18 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment;", "[0039] FIG. 19 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment;", "[0040] FIG. 20 shows a table of aspherical data of the optical imaging lens according to an example embodiment;", "[0041] FIG. 21( a ) shows the longitudinal spherical aberration, FIGS. 21( b ) and 21 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 21( d ) shows the distortion of the optical imaging lens of FIG. 18 ;", "[0042] FIG. 22 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment;", "[0043] FIG. 23 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment;", "[0044] FIG. 24 shows a table of aspherical data of the optical imaging lens according to an example embodiment;", "[0045] FIG. 25( a ) shows the longitudinal spherical aberration, FIGS. 25( b ) and 25 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 25( d ) shows the distortion of the optical imaging lens of FIG. 22 ;", "[0046] FIG. 26 shows a cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to an example embodiment;", "[0047] FIG. 27 shows a table of optical data of each lens element of the optical imaging lens according to an example embodiment;", "[0048] FIG. 28 shows a table of aspherical data of the optical imaging lens according to the seventh embodiment of the present invention;", "[0049] FIG. 29( a ) shows the longitudinal spherical aberration, FIGS. 29( b ) and 29 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 29( d ) shows the distortion of the optical imaging lens of FIG. 26 ;", "[0050] FIG. 30 shows a comparison table for the values of T2, T3, T2/Gaa and T3/Gaa of example embodiments;", "[0051] FIG. 31 shows a structure of an example embodiment of a mobile device;", "[0052] FIG. 32 shows an enlarged view of a structure of an example embodiment of a mobile device;", "and [0053] FIG. 33 shows another enlarged view of a structure of an example embodiment of a mobile device.", "DETAILED DESCRIPTION OF THE INVENTION [0054] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features.", "Persons having ordinary skill in the art will understand other varieties for implementing example embodiments, including those described herein.", "The drawings are not limited to specific scale and similar reference numbers are used for representing similar elements.", "As used in the disclosures and the appended claims, the terms “example embodiment,” “exemplary embodiment,” and “present embodiment”", "do not necessarily refer to a single embodiment, although it may, and various example embodiments may be readily combined and interchanged, without departing from the scope or spirit of the present invention.", "Furthermore, the terminology as used herein is for the purpose of describing example embodiments only and is not intended to be a limitation of the invention.", "In this respect, as used herein, the term “in”", "may include “in”", "and “on”, and the terms “a”, “an”", "and “the”", "may include singular and plural references.", "Furthermore, as used herein, the term “by”", "may also mean “from”, depending on the context.", "Furthermore, as used herein, the term “if”", "may also mean “when”", "or “upon”, depending on the context.", "Furthermore, as used herein, the words “and/or”", "may refer to and encompass any and all possible combinations of one or more of the associated listed items.", "[0055] Example embodiments of an optical imaging lens may comprise a first lens element, a second lens element, a third lens element, a fourth lens element, and a fifth lens element.", "These lens elements may be arranged in an order from an object side to an image side, and example embodiments of the lens as a whole may comprise the five lens elements with refractive power.", "In an example embodiment: the first lens element having positive refractive power comprises a convex object-side curved surface;", "the second lens element having negative refractive power comprises a concave image-side curved surface;", "the third lens element comprises an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a concave portion in a vicinity of a periphery of the third lens element and the image-side curved surface comprises a convex portion in a vicinity of a periphery of the third lens element;", "the fourth lens element comprises a convex image-side curved surface;", "the fifth lens element comprises an object-side curved surface and an image-side curved surface, wherein the object-side curved surface comprises a convex portion in a vicinity of the optical axis, the image-side curved surface comprises a concave portion in a vicinity of the optical axis.", "The central thickness of the second lens element the along the optical axis, T2, and the sum of all air gaps between the first lens element to the fifth lens element along the optical axis, Gaa, satisfy the relation as followed: [0000] 0.20 <T 2<0.50 (mm) equation (1);", "[0000] and [0000] 0.27<( T 2 /Gaa )<0.40 equation (2);", "[0000] and/or [0000] 0.21 <T 2<0.47 (mm) equation (1′);", "[0000] and [0000] 0.28<( T 2 /Gaa )<0.40 equation (2′);", "[0056] to achieve good optical characters and shortened length of the optical imaging lens.", "[0057] In some example embodiments, other thicknesses of lens along the optical axis and/or the ratio of which to the sum of all air gaps can be also controlled, and an example is provided with controlling a central thickness of the third lens element along the optical axis, T3, and/or controlling the ratio of T3 to Gaa to satisfy the relation: [0000] 0.20 <T 3<0.60 (mm) equation (3);", "[0000] and/or [0000] 0.30<( T 3 /Gaa )<0.45 equation (4);", "[0000] and/or [0000] 0.25 <T 3<0.57 (mm) equation (3′);", "[0000] and/or [0000] 0.31<( T 3 /Gaa )<0.45 equation (4′).", "[0058] Because example embodiments of the lens elements, such as aforesaid first lens element, second lens element, third lens element, fourth lens element, and fifth lens element, is preferable a lens elements made by injection-molding plastic, the thickness of the lens elements will affect the technical barrier and cost.", "For example, if the central thickness of the second lens element along the optical axis, T2, is less than the lower limit, 0.2 (mm), the center of the second lens element may be too thin and cause melting plastic material fail to pass the mold, and compared with currently technical level, the difficulty and cost for production in such situation are too high.", "It will be appreciated that the lower limits of above ranges of T2 and T3 are determined based on current technical levels.", "Further, the thicknesses of the first lens element, the second lens element, the third lens element, the fourth lens element, and fifth lens element affect the length of the optical imaging lens.", "For example, if the central thickness of the second lens element along the optical axis, T2, exceeds the upper limit, 0.5 (mm), the second lens element will be too thick and cause the length of the optical imaging lens to be too long and fail to match the request of a smaller optical imaging lens.", "Therefore, the upper limits of the above ranges of T2 and T3 are determined based on the preferable length of the optical imaging lens.", "When implementing example embodiments, more details about the convex or concave surface structure and/or the refractive power may be incorporated for one specific lens element or broadly for plural lens elements to enhance the control for the system performance and/or resolution, as illustrated in the following embodiments.", "It is noted that the details listed here could be incorporated in example embodiments if no inconsistency occurs.", "[0059] Several exemplary embodiments and associated optical data will now be provided for illustrating example embodiments of optical imaging lens with good optical characters and shortened lengths.", "Reference is now made to FIGS. 1-5 .", "FIG. 1 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a first example embodiment.", "FIG. 2 illustrates another example cross-sectional view of a lens element of the optical imaging lens according to an example embodiment.", "FIG. 3 depicts an example table of optical data of each lens element of the optical imaging lens according to an example embodiment.", "FIG. 4 depicts an example table of aspherical data of the optical imaging lens according to an example embodiment.", "FIG. 5 shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens according to an example embodiment.", "[0060] As shown in FIG. 1 , the optical imaging lens of the present embodiment comprises, in order from an object side A1 to an image side A2, an aperture stop 100 positioned at the object side of a first lens element 110 , the first lens element 110 , a second lens element 120 , a third lens element 130 , a fourth lens element 140 , and a fifth lens element 150 .", "Both of a filtering unit 160 and image plane 170 of an image sensor are positioned at the image side A2 of the optical imaging lens.", "The example embodiment of filtering unit 160 illustrated is an IR cut filter (infrared cut filter) positioned between the image-side curved surface 152 of the fifth lens element 150 and an image plane 170 , which filters out light with specific wavelength from the light passing optical imaging lens.", "For example, IR light is filtered out, and this will prohibit the IR light which is not seen by human eyes from producing an image on the image plane 170 .", "[0061] Exemplary embodiments of each lens elements of the optical imaging lens will now be described with reference to the drawings.", "[0062] An example embodiment of the first lens element 110 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 111 and a convex image-side curved surface 112 .", "The convex surface 111 and convex surface 112 may both be aspherical surfaces.", "[0063] The second lens element 120 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 121 having a concave portion 1211 in a vicinity of the optical axis, a concave portion 1212 neighboring the circumference, and a concave image-side curved surface 122 .", "The curved surface 121 and concave surface 122 may both be aspherical surfaces in a vicinity of the optical axis in a vicinity of the optical axis in a vicinity of a periphery of the fifth lens element 150 .", "[0064] The third lens element 130 may have positive refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 131 having a convex portion 1311 in a vicinity of the optical axis, and a concave portion 1312 in a vicinity of a periphery of the third lens element 130 , and an image-side curved surface 132 .", "The image-side curved surface 132 may comprise a concave portion 1321 in a vicinity of the optical axis and a convex portion 1322 in a vicinity of a periphery of the third lens element 130 .", "The curved surface 131 , 132 may both be aspherical surfaces.", "[0065] The fourth lens element 140 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 141 and a convex image-side curved surface 142 .", "The concave surface 141 and convex surface 142 may both be aspherical surfaces.", "[0066] The fifth lens element 150 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 151 , which may comprise a convex portion 1511 in a vicinity of the optical axis and a convex portion 1512 in a vicinity of a periphery of the fifth lens element 150 , and an image-side curved surface 152 , which may comprise a concave portion 1521 in a vicinity of the optical axis and a convex portion 1522 in a vicinity of a periphery of the fifth lens element 150 .", "The curved surface 151 and the curved surface 152 may both be gull wing surfaces of aspherical surfaces.", "[0067] In example embodiments, air gaps exist between the lens elements, the filtering unit 160 , and the image plane 170 of the image sensor.", "For example, FIG. 1 illustrates the air gaps d1 existing between the first lens element 110 and the second lens element 120 , the air gaps d2 existing between the second lens element 120 and the third lens element 130 , the air gaps d3 existing between the third lens element 130 and the fourth lens element 140 , the air gaps d4 existing between the fourth lens element 140 and the fifth lens element 150 , the air gaps d5 existing between fifth lens element 150 and the filtering unit 160 , and the air gaps d6 existing between the filtering unit 160 and the image plane 170 of the image sensor.", "However, in other embodiments, any of the aforesaid air gaps may or may not exist.", "For example, the profiles of opposite surfaces of any two adjacent lens elements may correspond to each other (attached together and therefore form one surface or do not form a surface at all), and in such situation, the air gaps may not exist.", "The sum of all air gaps d1, d2, d3, d4 between the first and fifth lens elements is denoted by Gaa.", "[0068] FIG. 3 depicts the optical characters of each lens elements in the optical imaging lens of the present embodiment, wherein the values of T2, T3, T2/Gaa and T3/Gaa are: [0069] T2=0.31000 (mm), satisfying equations (1), (1′);", "[0070] T2/Gaa=0.28999, satisfying equations (2), (2′);", "[0071] T3=0.34207 (mm), satisfying equations (3), (3′);", "[0072] T3/Gaa=0.31999, satisfying equations (4), (4′);", "[0073] wherein the distance from the object-side curved surface 111 of the first lens element 110 to the image-side curved surface 152 of the fifth lens element 150 is 3.75436 (mm), and the length of the optical imaging lens is shortened.", "[0074] Please note that, in example embodiments, to clearly illustrate the structure of each lens element, only the part where light passes, i.e. effective part, is shown.", "For example, taking the first lens element 110 as an example, FIG. 1 illustrates the convex object-side curved surface 111 and the convex image-side curved surface 112 .", "However, when implementing each lens element of the present embodiment, a non-effective part may be formed selectively.", "Based on the first lens element 110 , please refer to FIG. 2 , which illustrates the first lens element 110 comprising a further non-effective part.", "Here the non-effective part is not limited to a protruding part 113 for mounting the first lens element 110 in the optical imaging lens, and light will not pass through the protruding part 113 .", "[0075] As illustrated in FIG. 1 , the aspherical surfaces, including the convex surface 111 and the convex surface 112 of the first lens element 110 , the curved surface 121 and the concave surface 122 of the second lens element 120 , the curved surfaces 131 , 132 of the third lens element 130 , the concave surface 141 and the convex surface 142 of the fourth lens element 140 , and the curved surface 151 and the curved surface 152 of fifth lens element 150 , are all defined by the aspherical formula: [0000] Z  ( Y ) = Y 2 R / ( 1 + 1 - ( 1 + K )  Y 2 R 2 ) + ∑ i = 1 n  a 2  i × Y 2  i [0076] wherein: [0077] R represents the radius of the surface of the lens element;", "[0078] Z represents the depth of the aspherical surface (the perpendicular distance between the point of the aspherical surface at a distance Y from the optical axis and the tangent plane of the vertex on the optical axis of the aspherical surface);", "[0079] Y represents the perpendicular distance between the point of the aspherical surface and the optical axis;", "[0080] K represents a conic constant;", "[0081] a i represents an aspherical coefficient of i th level;", "[0082] and the values of each aspherical parameter are represented in FIG. 4 .", "[0083] As illustrated in FIGs (a) through (d), the optical imaging lens of present example embodiments show great characteristics in the longitudinal spherical aberration (a), astigmatism aberration in the sagittal direction (b), astigmatism aberration in the tangential direction (c), and/or distortion aberration (d).", "Therefore, according to above illustration, the optical imaging lens of example embodiments indeed achieve great optical performance and the length of the optical imaging lens is effectively shortened.", "[0084] Reference is now made to FIGS. 6-9 .", "FIG. 6 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a second example embodiment.", "FIG. 7 shows an example table of optical data of each lens element of the optical imaging lens according to the second example embodiment.", "FIG. 8 shows an example table of aspherical data of the optical imaging lens according to the second example embodiment.", "FIG. 9( a ) shows the longitudinal spherical aberration, FIGS. 9( b ) and 9 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 9( d ) shows the distortion of the optical imaging lens of FIG. 6 .", "[0085] As shown in FIG. 6 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises an aperture stop 200 positioned at the object side of a first lens element 210 , the first lens element 210 , a second lens element 220 , a third lens element 230 , a fourth lens element 240 , and a fifth lens element 250 .", "Both of a filtering unit 260 and an image plane 270 of an image sensor are positioned at the image side A2 of the optical imaging lens.", "In an example embodiment, filtering unit 260 is an IR cut filter positioned between the image-side curved surface 252 of the fifth lens element 250 and the image plane 270 to filter out light with specific wavelength from the light passing optical imaging lens.", "For example, IR light is filtered out, and this will prohibit the IR light which is not seen by human eyes from producing an image on image plane 270 .", "[0086] One difference between the second embodiments and the first embodiments is that the central thickness of lens T2 of the second lens element 220 and the central thickness of lens T3 of the third lens element 230 are different.", "In this regard, the sum of all air gaps Gaa from the first lens element 210 to the fifth lens element 250 may be different.", "Please refer to FIG. 7 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein the values of T2, T3, T2/Gaa and T3/Gaa are: [0087] T2=0.25763 (mm), satisfying equations (1), (1′);", "[0088] T2/Gaa=0.29805, satisfying equations (2), (2′);", "[0089] T3=0.27660 (mm), satisfying equations (3), (3′);", "[0090] T3/Gaa=0.32000, satisfying equations (4), (4′) [0091] wherein the distance from the object side of the first lens element to the image side of the fifth lens element is 3.68615 (mm) and the length of the optical imaging lens is shortened.", "[0092] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0093] The first lens element 210 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 211 and a convex image-side curved surface 212 .", "The convex surface 211 and convex surface 212 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 8 for values of the aspherical parameters.", "[0094] The second lens element 220 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 221 , which has a convex portion 2211 in a vicinity of the optical axis and a convex portion 2212 in a vicinity of a periphery of the second lens element 220 , and a concave image-side curved surface 222 .", "The curved surface 221 and concave surface 222 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 8 for values of the aspherical parameters.", "[0095] The third lens element 230 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 231 , which has a convex portion 2311 in a vicinity of the optical axis and a concave portion 2312 in a vicinity of a periphery of the third lens element 230 , and an image-side curved surface 232 , which has a concave portion 2321 in a vicinity of the optical axis and a convex portion 2322 in a vicinity of a periphery of the third lens element 230 .", "The curved surface 231 , 232 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 8 for values of the aspherical parameters.", "[0096] The fourth lens element 240 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 241 and a convex image-side curved surface 242 .", "The concave surface 241 and convex surface 242 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 8 for values of the aspherical parameters.", "[0097] The fifth lens element 250 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 251 , which has a convex portion 2511 in a vicinity of the optical axis and a convex portion 2512 in a vicinity of a periphery of the fifth lens element 250 , and an image-side curved surface 252 , which has a concave portion 2521 in a vicinity of the optical axis and a convex portion 2522 in a vicinity of a periphery of the fifth lens element 250 .", "The curved surface 251 , 252 may both be gull wing surfaces of the aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 8 for values of the aspherical parameters.", "[0098] In the present embodiment, similar to the first example embodiment, air gaps may exist between the lens elements 210 , 220 , 230 , 240 , 250 , the filtering unit 260 , and the image plane 270 of the image sensor.", "Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa.", "[0099] As shown in FIG. 9 , the optical imaging lens of the present embodiment shows great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d).", "Therefore, according to the above illustration, the optical imaging lens of the present embodiment indeed shows great optical performance and the length of the optical imaging lens is effectively shortened.", "[0100] Reference is now made to FIGS. 10-13 .", "FIG. 10 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a third example embodiment.", "FIG. 11 depicts an example table of optical data of each lens element of the optical imaging lens according to the third example embodiment.", "FIG. 12 depicts an example table of aspherical data of the optical imaging lens according to the third example embodiment.", "FIG. 13 shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens according to the third example embodiment.", "[0101] As shown in FIG. 10 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises a first lens element 310 , an aperture stop 300 positioned between the first lens element 310 and a second lens element 320 , the second lens element 320 , a third lens element 330 , a fourth lens element 340 , and a fifth lens element 350 .", "Both of a filtering unit 360 and an image plane 370 of an image sensor may be positioned at the image side A2 of the optical imaging lens.", "Here an example embodiment of the filtering unit 360 is an IR cut filter positioned between the image-side curved surface 352 of the fifth lens element 350 and the image plane 370 to filter out light with specific wavelength from the light passing optical imaging lens.", "For example, the IR light is filtered out, and this will prohibit the IR light which is not seen by human eyes from producing an image on image plane 370 .", "[0102] Please refer to FIG. 11 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein the values of T2, T3, T2/Gaa and T3/Gaa are: [0103] T2=0.25285 (mm), satisfying equations (1), (1′);", "[0104] T2/Gaa=0.31316, satisfying equations (2), (2′);", "[0105] T3=0.27452 (mm), satisfying equations (3), (3′);", "[0106] T3/Gaa=0.34000, satisfying equations (4), (4′);", "[0107] wherein the distance from the object side of the first lens element 310 to the image side of the fifth lens element 350 is 3.81589 (mm), and the length of the optical imaging lens is shortened.", "[0108] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0109] The first lens element 310 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 311 and a concave image-side curved surface 312 .", "The convex surface 311 and concave surface 312 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 12 for values of the aspherical parameters.", "[0110] The aperture stop 300 may be positioned between the first lens element 310 and the second lens element 320 .", "[0111] The second lens element 320 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 321 , which has a convex portion 3211 in a vicinity of the optical axis and a convex portion 3212 in a vicinity of a periphery of the second lens element 320 , and a concave image-side curved surface 322 .", "The curved surface 321 and concave surface 322 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 12 for values of the aspherical parameters.", "[0112] The third lens element 330 may have positive refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 331 , which has a convex portion 3311 in a vicinity of the optical axis and a concave portion 3312 in a vicinity of a periphery of the third lens element 330 , and an image-side curved surface 332 , which has a concave portion 3321 in a vicinity of the optical axis and a convex portion 3322 in a vicinity of a periphery of the third lens element 330 .", "The curved surface 331 , 332 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 12 for values of the aspherical parameters.", "[0113] The fourth lens element 340 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 341 and a convex image-side curved surface 342 .", "The concave surface 341 and convex surface 342 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 12 for values of the aspherical parameters.", "[0114] The fifth lens element 350 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 351 , which has a convex portion 3511 in a vicinity of the optical axis and a convex portion 3512 in a vicinity of a periphery of the fifth lens element 350 , and an image-side curved surface 352 , which has a concave portion 3521 in a vicinity of the optical axis and a convex portion 3522 in a vicinity of a periphery of the fifth lens element 350 .", "The curved surface 351 , 352 may both be gull wing surfaces of aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 12 for values of the aspherical parameters.", "[0115] In the present embodiment, for comparison, similar to the first embodiment, air gaps may exist between the lens elements 310 , 320 , 330 , 340 , 350 , the filtering unit 360 , and the image plane 370 of the image sensor.", "Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa.", "[0116] One difference between the third embodiment and the first embodiment is that the central thickness of lens T2 of the second lens element 320 and the central thickness of lens T3 of the third lens element 330 are different.", "In this regard, the sum of all air gaps Gaa from the first lens element 310 to the fifth lens element 350 may be different.", "Further, the aperture stop 300 of the present embodiment may be positioned between the first lens element 310 and the second lens element 320 , which may be different from the position of the aperture stop 100 in front of the first lens element 110 in the first embodiment.", "[0117] As illustrated in FIG. 13 , it is clear that the optical imaging lens of the present embodiment may achieve great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d).", "Therefore, according to above illustration, the optical imaging lens of the present embodiment indeed achieve great optical performance, and the length of the optical imaging lens is effectively shortened.", "[0118] Reference is now made to FIGS. 14-17 .", "FIG. 14 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a fourth example embodiment.", "FIG. 15 shows an example table of optical data of each lens element of the optical imaging lens according to the fourth example embodiment.", "FIG. 16 shows an example table of aspherical data of the optical imaging lens according to the fourth example embodiment.", "FIG. 17 shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens according to the fourth example embodiment.", "[0119] As shown in FIG. 14 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises an aperture stop 400 positioned at the object side of a first lens element 410 , the first lens element 410 , a second lens element 420 , a third lens element 430 , a fourth lens element 440 , and a fifth lens element 450 .", "Both of a filtering unit 460 and an image plane 470 of an image sensor may be positioned at the image side A2 of the optical imaging lens.", "Here an example embodiment of filtering unit 460 is an IR cut filter, which may be positioned between the image-side curved surface 452 of the fifth lens element 450 and the image plane 470 to filter out light with specific wavelength from the light passing optical imaging lens.", "For example, IR light may be filtered out, and this will prohibit the IR light which is not seen by human eyes from producing an image on image plane 470 .", "[0120] Please refer to FIG. 15 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein The values of T2, T3, T2/Gaa and T3/Gaa are: [0121] T2=0.45000 (mm), satisfying equations (1), (1′);", "[0122] T2/Gaa=0.39001, satisfying equations (2), (2′);", "[0123] T3=0.36920 (mm), satisfying equations (3), (3′);", "[0124] T3/Gaa=0.31998, satisfying equations (4), (4′);", "[0125] wherein the distance from the object side of the first lens element to the image side of the fifth lens element is 3.71940 (mm), and the length of the optical imaging lens is shortened.", "[0126] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0127] The first lens element 410 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 411 and a concave image-side curved surface 412 .", "The convex surface 411 and the concave surface 412 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 16 for values of the aspherical parameters.", "[0128] The second lens element 420 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 421 , which has a convex portion 4211 in a vicinity of the optical axis and a concave portion 4212 in a vicinity of a periphery of the second lens element 420 , and a concave image-side curved surface 422 .", "The curved surface 421 and concave surface 422 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 16 for values of the aspherical parameters.", "[0129] The third lens element 430 may have positive refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 431 , which has a convex portion 4311 in a vicinity of the optical axis and a concave portion 4312 in a vicinity of a periphery of the third lens element 430 , and an image-side curved surface 432 , which has a concave portion 4321 in a vicinity of the optical axis and a convex portion 4322 in a vicinity of a periphery of the third lens element 430 .", "The curved surface 431 , 432 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 16 for values of the aspherical parameters.", "[0130] The fourth lens element 440 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 441 and a convex image-side curved surface 442 .", "The concave surface 441 and convex surface 442 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 16 for values of the aspherical parameters.", "[0131] The fifth lens element 450 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 451 , which has a convex portion 4511 in a vicinity of the optical axis and a convex portion 4512 in a vicinity of a periphery of the fifth lens element 450 , and an image-side curved surface 452 , which has a concave portion 4521 in a vicinity of the optical axis and a convex portion 4522 in a vicinity of a periphery of the fifth lens element 450 .", "The curved surface 451 , 452 may both be gull wing surfaces of aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 16 for values of the aspherical parameters.", "[0132] In the present embodiment, for comparison, similar to the first embodiment, air gaps may exist between the lens elements 410 , 420 , 430 , 440 , 450 , the filtering unit 460 , and the image plane 470 of the image sensor.", "Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa.", "[0133] One difference between the fourth embodiment and the first embodiment is that the central thickness of lens T2 of the second lens element 420 and the central thickness of lens T3 of the third lens element 430 may be different.", "In this regard, the sum of all air gaps Gaa from the first lens element 410 to the fifth lens element 450 may be different.", "[0134] As illustrated in FIG. 17 , it is clear that the optical imaging lens of the present embodiment may achieve great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d).", "Therefore, according to above illustration, the optical imaging lens of the present embodiment indeed achieves great optical performance, and the length of the optical imaging lens is effectively shortened.", "[0135] Reference is now made to FIGS. 18-21 .", "FIG. 18 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a fifth embodiment.", "FIG. 19 shows an example table of optical data of each lens element of the optical imaging lens according to the fifth example embodiment.", "FIG. 20 shows an example table of aspherical data of the optical imaging lens according to the fifth example embodiment.", "FIG. 21 shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens according to the fifth example embodiment.", "[0136] As shown in FIG. 18 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises an aperture stop 500 positioned between the object side and a first lens element 510 , the first lens element 510 , a second lens element 520 , a third lens element 530 , a fourth lens element 540 , and a fifth lens element 550 .", "Both of a filtering unit 560 and an image plane 570 of an image sensor may be positioned at the image side A2 of the optical imaging lens.", "Here an example embodiment of filtering unit 560 is an IR cut filter, which may be positioned between the image-side curved surface 552 of the fifth lens element 550 and the image plane 570 to filter out light with specific wavelength from the light passing optical imaging lens.", "For example, IR light may be filtered out, and this will prohibit the IR light which is not seen by human eyes from producing an image on image plane 570 .", "[0137] Please refer to FIG. 19 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein The values of T2, T3, T2/Gaa and T3/Gaa are: [0138] T2=0.29660 (mm), satisfying equations (1), (1′);", "[0139] T2/Gaa=0.29001, satisfying equations (2), (2′);", "[0140] T3=0.45000 (mm), satisfying equations (3), (3′);", "[0141] T3/Gaa=0.44001, satisfying equations (4), (4′);", "[0142] wherein the distance from the object side of the first lens element to the image side of the fifth lens element is 3.70690 (mm), and the length of the optical imaging lens is shortened.", "[0143] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0144] The first lens element 510 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 511 and a concave image-side curved surface 512 .", "The convex surface 511 and concave surface 512 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 20 for values of the aspherical parameters.", "[0145] The second lens element 520 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 521 , which has a convex portion 5211 in a vicinity of the optical axis and a convex portion 5212 in a vicinity of a periphery of the second lens element 520 , and a concave image-side curved surface 522 .", "The curved surface 521 and concave surface 522 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 20 for values of the aspherical parameters.", "[0146] The third lens element 530 may have positive refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 531 , which has a concave portion 5311 in a vicinity of the optical axis and a concave portion 5312 in a vicinity of a periphery of the third lens element 530 , and an image-side curved surface 532 , which has a convex portion 5321 in a vicinity of the optical axis and a convex portion 5322 in a vicinity of a periphery of the third lens element 530 .", "The curved surface 531 , 532 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 20 for values of the aspherical parameters.", "[0147] The fourth lens element 540 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 541 and a convex image-side curved surface 542 .", "The concave surface 541 and convex surface 542 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 20 for values of the aspherical parameters.", "[0148] The fifth lens element 550 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 551 , which has a convex portion 5511 in a vicinity of the optical axis and a convex portion 5512 in a vicinity of a periphery of the fifth lens element 550 , and an image-side curved surface 552 , which has a concave portion 5521 in a vicinity of the optical axis and a convex portion 5522 in a vicinity of a periphery of the fifth lens element 550 .", "The curved surfaces 551 , 552 may both be gull wing surfaces of aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 20 for values of the aspherical parameters.", "[0149] In the present embodiment, for comparison, similar to the first embodiment, air gaps may exist between the lens elements 510 , 520 , 530 , 540 , 550 , the filtering unit 560 , and the image plane 570 of the image sensor.", "Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa.", "[0150] One difference between the fifth embodiment and the first embodiment is that the central thickness of lens T2 of the second lens element 520 and the central thickness of lens T3 of the third lens element 530 may be different.", "Therefore, the sum of all air gaps Gaa from the first lens element 510 to the fifth lens element 550 may be different.", "[0151] As illustrated in FIG. 21 , it is clear that the optical imaging lens of the present embodiment may show great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d).", "Therefore, according to above illustration, the optical imaging lens of the present embodiment indeed achieves great optical performance, and the length of the optical imaging lens is effectively shortened.", "[0152] Reference is now made to FIGS. 22-25 .", "FIG. 22 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a sixth example embodiment.", "FIG. 23 shows an example table of optical data of each lens element of the optical imaging lens according to the sixth example embodiment.", "FIG. 24 shows an example table of aspherical data of the optical imaging lens according to the sixth example embodiment.", "FIG. 25( a ) shows the longitudinal spherical aberration, FIGS. 25( b ) and 25 ( c ) show the respective astigmatic field curves in the sagittal and tangential direction, and FIG. 25( d ) shows the distortion according to the sixth example embodiment.", "[0153] As shown in FIG. 22 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises an aperture stop 600 positioned between the object side and a first lens element 610 , the first lens element 610 , a second lens element 620 , a third lens element 630 , a fourth lens element 640 , and a fifth lens element 650 .", "Both of a filtering unit 660 and an image plane 670 of an image sensor may be positioned at the image side A2 of the optical imaging lens.", "Here an example embodiment of filtering unit 660 may be an IR cut filter, which may be positioned between the image-side curved surface 652 of the fifth lens element 650 and the image plane 670 to filter out light with specific wavelength from the light passing optical imaging lens.", "For example, IR light may be filtered out, and this may prohibit the IR light which is not seen by human eyes from producing an image on image plane 670 .", "[0154] Please refer to FIG. 23 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein The values of T2, T3, T2/Gaa and T3/Gaa are: [0155] T2=0.36250 (mm), satisfying equations (1), (1′);", "[0156] T2/Gaa=0.29000, satisfying equations (2), (2′);", "[0157] T3=0.55000 (mm), satisfying equations (3), (3′);", "[0158] T3/Gaa=0.44000, satisfying equations (4), (4′);", "[0159] wherein the distance from the object side of the first lens element to the image side of the fifth lens element is 3.84120 (mm), and the length of the optical imaging lens is shortened.", "[0160] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0161] The first lens element 610 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 611 and a concave image-side curved surface 612 .", "The convex surface 611 and 612 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 24 for values of the aspherical parameters.", "[0162] The second lens element 620 may have negative refractive power, which may be constructed by plastic material, and may be an object-side curved surface 621 , which has a convex portion 6211 in a vicinity of the optical axis and a convex portion 6212 in a vicinity of a periphery of the second lens element 620 , and a concave image-side curved surface 622 .", "The curved surface 621 and concave surface 622 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 24 for values of the aspherical parameters.", "[0163] The third lens element 630 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 631 , which has a concave portion 6311 in a vicinity of the optical axis and a concave portion 6312 in a vicinity of a periphery of the third lens element 630 , and an image-side curved surface 632 , which has a concave portion 6321 in a vicinity of the optical axis and a convex portion 6322 in a vicinity of a periphery of the third lens element 630 .", "The curved surface 631 , 632 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 24 for values of the aspherical parameters.", "[0164] The fourth lens element 640 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 641 and a convex image-side curved surface 642 .", "The concave surface 641 and convex surface 642 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 24 for values of the aspherical parameters.", "[0165] The fifth lens element 650 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 651 , which has a convex portion 6511 in a vicinity of the optical axis and a convex portion 6512 in a vicinity of a periphery of the fifth lens element 650 , and an image-side curved surface 652 , which has a concave portion 6521 in a vicinity of the optical axis and a convex portion 6522 in a vicinity of a periphery of the fifth lens element 650 .", "The curved surface 651 , 652 may both be gull wing surfaces of aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 24 for values of the aspherical parameters.", "[0166] In the present embodiment, for comparison, similar to the first embodiment, air gaps may exist between the lens elements 610 , 620 , 630 , 640 , 650 , the filtering unit 660 , and the image plane 670 of the image sensor.", "Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa.", "[0167] One difference between the sixth embodiment and the first embodiment is that the central thickness of lens T2 of the second lens element 620 and the central thickness of lens T3 of the third lens element 630 may be different.", "In this regard, the sum of all air gaps Gaa from the first lens element 610 to the fifth lens element 650 may be different.", "[0168] As illustrated in FIG. 25 , it is clear that the optical imaging lens of the present embodiment may show great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d).", "Therefore, according to above illustration, the optical imaging lens of the present embodiment indeed achieves great optical performance, and the length of the optical imaging lens is effectively shortened.", "[0169] Reference is now made to FIGS. 26-29 .", "FIG. 26 illustrates an example cross-sectional view of an optical imaging lens having five lens elements of the optical imaging lens according to a seventh example embodiment.", "FIG. 27 shows an example table of optical data of each lens element of the optical imaging lens according to the seventh example embodiment.", "FIG. 28 shows an example table of aspherical data of the optical imaging lens according to the seventh example embodiment.", "FIG. 29 shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens according to the seventh example embodiment.", "[0170] As shown in FIG. 26 , the optical imaging lens of the present embodiment, in an order from an object side A1 to an image side A2, comprises an aperture stop 700 positioned between the object side and a first lens element 710 , the first lens element 710 , a second lens element 720 , a third lens element 730 , a fourth lens element 740 , and a fifth lens element 750 .", "Both of a filtering unit 760 and an image plane 770 of an image sensor may be positioned at the image side A2 of the optical imaging lens.", "Here an example embodiment of filtering unit 760 may comprise an IR cut filter, which is positioned between the image-side curved surface 752 of the fifth lens element 750 and the image plane 770 to filter out light with specific wavelength from the light passing optical imaging lens.", "For example, IR light is filtered out, and this may prohibit the IR light which is not seen by human eyes from producing an image on image plane 770 .", "[0171] Please refer to FIG. 27 for the optical characteristics of each lens elements in the optical imaging lens of the present embodiment, wherein The values of T2, T3, T2/Gaa and T3/Gaa are: [0172] T2=0.21999 (mm), satisfying equations (1), (1′);", "[0173] T2/Gaa=0.28974, satisfying equations (2), (2′);", "[0174] T3=0.26816 (mm), satisfying equations (3), (3′);", "[0175] T3/Gaa=0.35319, satisfying equations (4), (4′);", "[0176] wherein the distance from the object side of the first lens element to the image side of the fifth lens element is 3.59439 (mm), and the length of the optical imaging lens is shortened.", "[0177] Example embodiments of the lens elements of the optical imaging lens may comprise the following example embodiments: [0178] The first lens element 710 may have positive refractive power, which may be constructed by plastic material, and may comprise a convex object-side curved surface 711 and a concave image-side curved surface 712 .", "The surfaces 711 and 712 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 28 for values of the aspherical parameters.", "[0179] The second lens element 720 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 721 , which has a convex portion 7211 in a vicinity of the optical axis and a convex portion 7212 in a vicinity of a periphery of the second lens element 720 , and a concave image-side curved surface 722 .", "The curved surface 721 and concave surface 722 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 28 for values of the aspherical parameters.", "[0180] The third lens element 730 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 731 , which has a concave portion 7311 in a vicinity of the optical axis and a concave portion 7312 in a vicinity of a periphery of the third lens element 730 , and an image-side curved surface 732 , which has a convex portion 7321 in a vicinity of the optical axis and a convex portion 7322 in a vicinity of a periphery of the third lens element 730 .", "The curved surfaces 731 , 732 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 28 for values of the aspherical parameters.", "[0181] The fourth lens element 740 may have positive refractive power, which may be constructed by plastic material, and may comprise a concave object-side curved surface 741 and a convex image-side curved surface 742 .", "The concave surface 741 and convex surface 742 may both be aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 28 for values of the aspherical parameters.", "[0182] The fifth lens element 750 may have negative refractive power, which may be constructed by plastic material, and may comprise an object-side curved surface 751 , which has a convex portion 7511 in a vicinity of the optical axis and a convex portion 7512 in a vicinity of a periphery of the fifth lens element 750 , and an image-side curved surface 752 , which has a concave portion 7521 in a vicinity of the optical axis and a convex portion 7522 in a vicinity of a periphery of the fifth lens element 750 .", "The curved surfaces 751 , 752 may both be gull wing surfaces of aspherical surfaces defined by the aspherical formula.", "Please refer to FIG. 28 for values of the aspherical parameters.", "[0183] In the present embodiment, for comparison, similar to the first embodiment, air gaps may exist between the lens elements 710 , 720 , 730 , 740 , 750 , the filtering unit 760 , and the image plane 770 of the image sensor.", "Please refer to the positions of the air gaps d1, d2, d3, d4, d5, d6 marked in the first embodiment, wherein the sum of the air gaps d1, d2, d3, d4 is Gaa.", "[0184] One difference between the seventh embodiment and the first embodiment is the central thickness of lens T2 of the second lens element 720 and the central thickness of lens T3 of the third lens element 730 may be different.", "In this regard, the sum of all air gaps Gaa from the first lens element 710 to the fifth lens element 750 may be different.", "[0185] As illustrated in FIG. 29 , it is clear that the optical imaging lens of the present embodiment may show great characteristics in longitudinal spherical aberration (a), astigmatism in the sagittal direction (b), astigmatism in the tangential direction (c), or distortion aberration (d).", "Therefore, according to above illustration, the optical imaging lens of the present embodiment indeed achieves great optical performance, and the length of the optical imaging lens is effectively shortened.", "[0186] Please refer to FIG. 30 , which shows the values of T2, T3, T2/Gaa and T3/Gaa of all seven embodiments.", "As shown, this table provides a clear illustration that the optical imaging lens of example embodiments indeed satisfies the equations (1), (2), (3), (4), (1′), (2′), (3′), and (4′).", "[0187] Reference is now made to FIGS. 31-32 .", "FIG. 31 illustrates an example structural view of an example embodiment of mobile device 1 .", "FIG. 32 shows an example enlarged view of the example embodiment of mobile device 1 of FIG. 31 .", "An example of the mobile device 1 may be a mobile phone, but the type of the mobile device 1 should not be limited to such.", "As shown, the mobile device 1 may comprise a housing 10 and an optical imaging lens assembly 20 positioned in the housing 10 .", "The housing 10 protects the optical imaging lens assembly 20 therein, and is not limited to any shape or material.", "The optical imaging lens assembly 20 may comprise a lens barrel 21 , an optical imaging lens 22 , a module housing unit 23 , and an image sensor 171 which is positioned at an image side of the optical imaging lens 22 .", "In example embodiments, any optical imaging lens may be used as the optical imaging lens 22 , such as any optical imaging lens disclosed in the aforesaid embodiments or other optical imaging lens according to example embodiments.", "However, for clearly illustrating the present embodiment, the optical imaging lens of the first embodiment will be used as the optical imaging lens 22 .", "When using other optical imaging lens 22 , the structure of the filtering unit 160 may be omitted.", "Furthermore, the housing 10 , the lens barrel 21 , and/or the module housing unit 23 may be integrated into a single component or assembled by multiple components.", "Furthermore, the image sensor 171 used in the present embodiment is directly attached on the substrate 172 in the form of a chip on board (COB) package, and such package is different from traditional chip scale packages (CSP) since it does not require a cover glass.", "That is, no cover glass is required before the image sensor 171 in the optical imaging lens 22 .", "It should be noted, however, that example embodiments are not limited to this package type.", "The optical imaging lens with refractive power as a whole comprises five lens elements 110 , 120 , 130 , 140 , 150 positioned in the lens barrel 21 , wherein an air gap may exist between any two adjacent lens elements.", "The module housing unit 23 is provided for positioning the optical imaging lens 22 thereon, and preferably comprises an image sensor base 233 and an auto focus module 234 .", "The image sensor base 233 may be fixed on the substrate 172 , and the auto focus module 234 may comprise a lens seat 2341 for positioning the optical imaging lens 22 .", "The lens seat 2341 may be capable of moving back and forth along the optical axis to control the focusing of the optical imaging lens 22 .", "For example, according to the distance of the object, the optical imaging lens 22 may be moved back and forth until the image focuses on the image plane 170 of the image sensor 171 .", "Because the length of the optical imaging lens 22 is merely 3.75436 (mm), the size of the mobile device 1 may be quite small with good optical characters.", "Therefore, the present embodiment meets the demand of smaller sized product design and the request of the market.", "[0188] Reference is now made to FIG. 33 , which shows a structural view of an example embodiment of mobile device 2 .", "Here the housing is not shown, and only the optical imaging lens assembly 20 is shown.", "As shown, one difference between the mobile device 2 and the mobile device 1 may be the structure of the module housing unit 24 .", "The module housing unit 24 may comprise an image sensor base 243 and an auto focus module 244 , which may comprise a voice coil motor (VCM) comprising a lens seat 2441 , a magnet 2442 and a coil 2443 .", "With the magnetic force produced by the magnet 2442 and the coil 2443 , the VCM may move the lens seat 2441 slightly to move the lens seat 2441 back and forth along an optical axis to focus the optical imaging lens 22 .", "Because the length of the optical imaging lens 22 may be shortened, the mobile device 2 may be designed with a smaller size and meanwhile good optical performance is still provided.", "Therefore, the present embodiment meets the demand of small sized product design and the request of the market.", "[0189] According to above illustration, it is clear that the mobile device and the optical imaging lens thereof in example embodiments, through controlling ratio of at least one central thickness of lens to a sum of all air gaps along the optical axis between five lens elements in a predetermined range, and incorporated with detail structure and/or reflection power of the lens elements, the lengths of the optical imaging lens is effectively shortened and meanwhile good optical characters are still provided.", "[0190] While various embodiments in accordance with the disclosed principles have been described above, it should be understood that they have been presented by way of example only, and are not limiting.", "Thus, the breadth and scope of exemplary embodiment(s) should not be limited by any of the above-described embodiments, but should be defined only in accordance with the claims and their equivalents issuing from this disclosure.", "Furthermore, the above advantages and features are provided in described embodiments, but shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages.", "[0191] Additionally, the section headings herein are provided for consistency with the suggestions under 37 C.F.R. 1.77 or otherwise to provide organizational cues.", "These headings shall not limit or characterize the invention(s) set out in any claims that may issue from this disclosure.", "Specifically, a description of a technology in the “Background”", "is not to be construed as an admission that technology is prior art to any invention(s) in this disclosure.", "Furthermore, any reference in this disclosure to “invention”", "in the singular should not be used to argue that there is only a single point of novelty in this disclosure.", "Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s), and their equivalents, that are protected thereby.", "In all instances, the scope of such claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings herein." ]
BACKGROUND OF THE INVENTION The invention relates to cutting or severing apparatus in general, and more particularly to improvements in apparatus for cutting stacks of sheets or discrete sheets of paper or the like. Still more particularly, the invention relates to improvements in cutting or severing apparatus of the type having one or more severing units each of which includes a mobile knife and a stationary knife or counterknife. The position of the cutting edge of one knife relative to the other knife of a severing unit for paper sheets or the like must be adjusted from time to time. As a rule, the adjusting mechanism includes displacing elements in the form of bolts or wedges which are installed in a holder for the blade of the knife and are movable to thereby change the position of the cutting edge of the blade. Reference may be had, for example, to U.S. Pat. No. 4,392,402 granted Jul. 12, 1983 to Rann. This patent describes an apparatus for severing running webs of paper or the like. The apparatus has a set of counterknives which orbit at one side of the path for the running web and a set of knives with adjustable blades which orbit at the other side of the path to cooperate with the orbiting counterknives in order to sever the running web transversely of the direction of longitudinal movement of the web. The adjustable blades are mounted on a common rotary holder and their positions relative to the common holder (and hence relative to the associated counterknives) can be changed by wedges which are accessible at the periphery of the common holder. The just described apparatus is quite satisfactory for the severing of a single running web or of several overlapping running webs because the adjusting wedges are accessible at the periphery of the rotating holder for the knife blades. However, the situation is different if several cutting or severing units are placed side-by-side in close proximity to each other, e.g., to simultaneously sever a single sheet or several overlapping sheets of paper or the like. Adjusting mechanisms for the blades of such closely adjacent severing units are not readily accessible so that each unit wherein the blade necessitates adjustment must be detached from the reciprocating mechanism for the mobile knives of the severing units before the adjusting mechanism for the blade is accessible for manipulation in order to change the position of the cutting edge of the blade with reference to the blade holder. All this takes up much time and can cause considerable losses in the output of a production line for steno pads, exercise pads and/or other stationery products. Cutting apparatus with several parallel severing units are often utilized in production lines wherein stacks of relatively large paper sheets are severed at a plurality of locations to convert the stacks into discrete pads or like stationery products wherein the sheets are held together by helical binders, by strips of adhesive or in any other suitable way. Dismantling of the severing apparatus for the sole purpose of adjusting the cutting edge of the blade in a single severing unit would entail huge losses in the output of such production lines. OBJECTS OF THE INVENTION An object of the invention is to provide a severing apparatus for paper sheets or the like wherein the position or positions of the cutting edge or edges of one or more blades relative to their holders can be adjusted in a simple and time-saving manner even if the blades of two or more severing units are immediately or closely adjacent each other. Another object of the invention is to provide a novel and improved adjusting mechanism for the cutting edges of blades in severing apparatus employing two or more closely adjacent sheet severing units. A further object of the invention is to provide a novel and improved mechanism for adjusting the position of a blade relative to its holder in a severing unit wherein only the end faces of the holder are accessible when the severing unit is ready for use. An additional object of the invention is to provide a novel and improved holder for use in the above outlined severing apparatus. Still another object of the invention is to provide a simple, compact and inexpensive blade adjusting mechanism which can be installed in existing types of sheet severing apparatus as a superior substitute for heretofore known adjusting mechanisms. A further object of the invention is to provide an adjusting mechanism which can be reached and manipulated without necessitating even partial dismantling of the severing apparatus. Another object of the invention is to provide an adjusting mechanism which renders it possible to place two or more discrete severing units into immediate or very close proximity to each other without adversely affecting the accessibility of the adjusting mechanism. A further object of the invention is to provide a novel and improved method of installing the adjusting mechanism in the holder for the blade of a mobile knife in a paper sheet cutting apparatus. An additional object of the invention is to provide a production line for stationery products which embodies one or more adjusting mechanisms of the above outlined character. SUMMARY OF THE INVENTION The invention is embodied in an apparatus for severing sheet-like materials (e.g., stacks of paper sheets). The improved apparatus comprises at least one severing unit including a first knife and a second knife, and means for moving one of the knives relative to the other knife whereby the knives sever one or more sheets which are placed between them while the knives are spaced apart from each other. The first knife comprises a blade having an elongated cutting edge and a surface extending along the cutting edge, a holder having an elongated side face adjacent the surface of the blade and at least one end face at one end of the side face, means (e.g., bolts remote from the cutting edge) for connecting the blade to the holder, and means for adjusting the blade relative to the holder, namely for adjusting the location of the cutting edge relative to the second knife (e.g., in order to compensate for wear). The adjusting means comprises a plurality of displacing elements which are recessed into the side face and are movable transversely of and against the surface of the blade (preferably between the cutting edge and the connecting means), a moving element for each of the displacing elements, and devices for transmitting motion between the moving elements and the respective displacing elements. The moving elements are accessible at the at least one end face of the holder and are movable in the holder in substantial parallelism with the cutting edge of the blade. The one knife is preferably the first knife of the at least one severing unit, and the second knife of such unit is preferably a stationary counterknife. The moving elements can include or constitute pressure transmitting bolts having axes which are at least substantially parallel to the cutting edge of the blade. Such moving elements are preferably provided with external threads and are rotatable in tapped bores or holes of the holder; the tapped bores extend inwardly from the at least one end face of the holder and communicate with discrete holes or bores for the corresponding displacing elements. The bores or holes for the displacing elements extend at right angles to the surface of the blade and hence at right angles to the side face of the holder. Each motion transmitting device can include a wedge which is operative to move the respective displacing element in its hole or bore in response to movement of the corresponding moving element in its hole or bore. Each wedge has a first surface which is inclined relative to the surface of the blade, and each displacing element has a second surface which is complementary to and abuts the surface of the respective wedge. The displacing and moving elements are or can be disposed in a common plane, e.g., in a substantially horizontal plane which is at least substantially normal to the surface of the blade and to the side face of the holder. The holder preferably includes a second end face at the other end of the elongated side face, and the adjusting means preferably further comprises at least one additional displacing element which is recessed into the side face of the holder and is movable transversely of and against the surface of the blade, an additional moving element which is accessible at the second end face of the holder and is movable in the holder in substantial parallelism with the cutting edge, and an additional device for transmitting motion from the additional moving element to the additional displacing element. The side face of the holder includes a first half which is adjacent the at least one end face and a second half which is adjacent the second end face. The at least one additional displacing element is recessed into the second half and the displacing elements which receive motion from moving elements that are accessible at the at least one end face of the holder are recessed into the first half of the side face. The arrangement is preferably such that each moving element at the at least one end face and the associated motion transmitting device and displacing element are mirror images of a moving element which is accessible at the second end face and of the associated motion transmitting device and displacing element. The apparatus preferably further comprises at least one additional severing unit having a first knife and a second knife. One knife of the at least one additional severing unit is connected to and is movable by the moving means for the one knife of the at least one severing unit. The severing units are preferably closely or immediately adjacent each other. The cutting edge of the blade of the first knife of the at least one severing unit is preferably parallel to the cutting edge of the blade of the one knife of the at least one additional severing unit. The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic side elevational view of a severing apparatus with a plurality of severing units each of which embodies one form of the invention; FIG. 2 is a side elevational view of one of the severing units, substantially as seen in the direction of arrow II in FIG. 1; FIG. 3 is an end elevational view of the severing unit as shown in FIG. 2; and FIG. 4 is a fragmentary sectional view substantially as seen in the direction of arrows from the line IV--IV in FIG. 2. DESCRIPTION OF PREFERRED EMBODIMENTS The severing apparatus 1 of FIG. 1 can be used in a production line for writing pads, exercise pads, steno pads and analogous stationery products. The apparatus 1 is designed to simultaneously sever a stack of overlapping sheets 2 into a plurality of smaller sections in the form of strips or the like extending at right angles to the plane of FIG. 1. To this end, the apparatus 1 comprises a plurality of rather closely adjacent parallel severing units 3 each having a mobile first knife 6, 7 and a stationary second knife or counterknife 4 beneath the respective mobile knife. The mobile knives have elongated parallel holders 7 which are affixed to or form part of a common moving member 8 serving to move the holders 7 up and down away from and toward the respective counterknives 4. A sheet 2 or a stack of sheets 2 is introduced between the stationary counterknives 4 and the lifted elongated blades 6 of the mobile knives before the holders 7 are caused to descend whereby the cutting edges 6a of the blades 6 cooperate with the cutting edges 4a of the counterknives 4 to sever the sheet or sheets 2. The means for moving the member 8 up and down in the frame of the severing apparatus 1 can comprise one or more fluid-operated cylinder and piston assemblies or the like, not shown. FIG. 1 further shows hold-down devices 9 which are mounted on the member 8 and cooperate with the adjacent counterknives 4 to prevent shifting of the sheet or sheets 2 in the course of a severing operation. The details of one severing unit 3 are shown in FIGS. 2, 3 and 4. This unit comprises an elongated knife blade holder 7 having two end faces 17, 18 which are accessible when the holder 7 is mounted on the member 8 in close proximity to the holder or holders 7 of one or two neighboring severing units 3, and an elongated upright side face 7a which abuts the surface 6b of the blade 6. The cutting edge 6a of the blade 6 extends all the way between its end faces which may but need not be coplanar with the respective end faces 17, 18 of the holder 7. The means for connecting the blade 6 to the holder 7 comprises a row of parallel externally threaded bolts 107 which are remote from the cutting edge 6a and extend at right angles to the planes of the surface 6b and side face 7a. The blade 6 is at least slightly flexible in the region between the shanks of the connecting bolts 107 and the cutting edge 6a, and the mechanism for adjusting the blade 6 and hence the cutting edge 6a relative to the corresponding counterknife 4 is installed in the holder 7 and includes moving elements in the form of externally threaded bolts 12 which are accessible at the two end faces 17 and 18. To this end, the holder 7 is provided with sets of parallel tapped bores or holes 13 which are parallel to the side face 7a and extend in substantial parallelism with the cutting edge 6a. The external threads of the moving elements or bolts 12 are in mesh with the internal threads of the holder 7, and the heads of the elements 12 are accessible at the respective end faces 17, 18 so that a screwdriver or another elementary tool can be employed to move the elements 12 axially and to thus change the axial positions of associated pin-shaped cylindrical displacing elements 11 which are recessed into the side face 7a of the holder 7 and engage the adjacent surface 6b of the blade 6 between the bolts 107 and the cutting edge 6a. The adjusting mechanism for the blade 6 further comprises wedge-shaped motion transmitting devices 14 which are reciprocable in the bores or holes 13 for the respective moving elements 12 and have surfaces 14a inclined relative to the side face 7a and abutting complementary surfaces 11a at the inner ends of the displacing elements 11. The elements 11 are reciprocable in bores or holes 16 which are machined into or are otherwise formed in the holder 7 and are normal to the side face 7a (and hence to the surface 6b when the blade 6 is properly connected to the holder by bolts 107). The moving elements 12, the displacing elements 11, and the motion transmitting devices 14 are disposed in a common horizontal plane which is normal to the side face 7a. FIG. 2 shows that the blade 6 is adjustable by a set of six equidistant displacing elements 11. The bores or holes 16 for the three right-hand displacing elements 11 are provided in the right-hand half of the side face 7a, namely in that half which is adjacent the end face 18, and the bores or holes 16 for the other three displacing elements 11 are provided in the left-hand half of the side face 7a (i.e., in that half which is adjacent the end face 17). The number of bores or holes 16 in the one half of the side face 7a may but need not equal the number of holes or bores 16 in the other half of such side face. It is further possible to provide moving elements 12 only at one longitudinal end of the holder 7 if the number of displacing elements 11 is relatively small (i.e., if the blade 6 is relatively short) and/or if the end face 17 or 18 is not accessible when the respective severing unit 3 is assembled with one or more additional severing units 3 to form part of the apparatus 1. The operation of the adjusting mechanism will be readily understood upon perusal of the preceding description. Thus, rotation of the moving elements 12 relative to the holder 7 in a direction to move the elements 12 deeper into the respective bores or holes 13 entails a corresponding movement of the associated wedge-like motion transmitting devices 14 whereby the inclined surfaces 14a of the devices 14 move relative to the adjacent surfaces 11a and move the elements 11 in the respective bores or holes 16 so that the corresponding portions of the cutting edge 6a are moved away from the side face 7a of the holder. If the moving elements 12 are rotated in the opposite direction, innate elasticity of the blade 6 causes the cutting edge 6a to move nearer to the side face 7a of the holder 7. Each bore or hole 16 can extend all the way through the holder 7, i.e., from the side face 7a to the side face 7b (see FIG. 4). An important advantage of the improved severing units 3 and of their adjusting mechanisms is that the heads of the moving elements 12 are accessible at the end faces 17 and 18 of the respective holders 7. Such end faces are normally accessible to the working ends of tools even if the severing units 3 are installed in immediate or close proximity to each other. Therefore, the positions of the cutting edges 6a relative to the associated holders 7 and counterknives 4 can be adjusted without necessitating even partial dismantling of the severing apparatus 1. Such adjustments can be carried out irrespective of the mutual spacing of neighboring severing units 3, i.e., such spacing can be selected exclusively in dependency on the desired width of strips or stacks of strips which are to be obtained in response to each lowering of the member 8. The latter is connected to the holders 6 by sets of bolts 108. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the appended claims.
A paper cutting apparatus with several closely adjacent severing units wherein each unit includes a stationary counterknife and a mobile knife which cooperates with the respective counterknife to sever a stack of paper sheets between them. The mobile knives have holders which are connected to a common reciprocating member, and elongated blades which are bolted to the respective holders. The positions of cutting edges of the blades relative to the corresponding counterknives are adjustable by threaded bolts which are accessible at the end faces of the holders and can transmit motion to discrete blade-displacing elements by way of discrete wedges. The displacing elements are recessed into those side faces of the holders which are adjacent the respective blades.
Identify and summarize the most critical technical features from the given patent document.
[ "BACKGROUND OF THE INVENTION The invention relates to cutting or severing apparatus in general, and more particularly to improvements in apparatus for cutting stacks of sheets or discrete sheets of paper or the like.", "Still more particularly, the invention relates to improvements in cutting or severing apparatus of the type having one or more severing units each of which includes a mobile knife and a stationary knife or counterknife.", "The position of the cutting edge of one knife relative to the other knife of a severing unit for paper sheets or the like must be adjusted from time to time.", "As a rule, the adjusting mechanism includes displacing elements in the form of bolts or wedges which are installed in a holder for the blade of the knife and are movable to thereby change the position of the cutting edge of the blade.", "Reference may be had, for example, to U.S. Pat. No. 4,392,402 granted Jul. 12, 1983 to Rann.", "This patent describes an apparatus for severing running webs of paper or the like.", "The apparatus has a set of counterknives which orbit at one side of the path for the running web and a set of knives with adjustable blades which orbit at the other side of the path to cooperate with the orbiting counterknives in order to sever the running web transversely of the direction of longitudinal movement of the web.", "The adjustable blades are mounted on a common rotary holder and their positions relative to the common holder (and hence relative to the associated counterknives) can be changed by wedges which are accessible at the periphery of the common holder.", "The just described apparatus is quite satisfactory for the severing of a single running web or of several overlapping running webs because the adjusting wedges are accessible at the periphery of the rotating holder for the knife blades.", "However, the situation is different if several cutting or severing units are placed side-by-side in close proximity to each other, e.g., to simultaneously sever a single sheet or several overlapping sheets of paper or the like.", "Adjusting mechanisms for the blades of such closely adjacent severing units are not readily accessible so that each unit wherein the blade necessitates adjustment must be detached from the reciprocating mechanism for the mobile knives of the severing units before the adjusting mechanism for the blade is accessible for manipulation in order to change the position of the cutting edge of the blade with reference to the blade holder.", "All this takes up much time and can cause considerable losses in the output of a production line for steno pads, exercise pads and/or other stationery products.", "Cutting apparatus with several parallel severing units are often utilized in production lines wherein stacks of relatively large paper sheets are severed at a plurality of locations to convert the stacks into discrete pads or like stationery products wherein the sheets are held together by helical binders, by strips of adhesive or in any other suitable way.", "Dismantling of the severing apparatus for the sole purpose of adjusting the cutting edge of the blade in a single severing unit would entail huge losses in the output of such production lines.", "OBJECTS OF THE INVENTION An object of the invention is to provide a severing apparatus for paper sheets or the like wherein the position or positions of the cutting edge or edges of one or more blades relative to their holders can be adjusted in a simple and time-saving manner even if the blades of two or more severing units are immediately or closely adjacent each other.", "Another object of the invention is to provide a novel and improved adjusting mechanism for the cutting edges of blades in severing apparatus employing two or more closely adjacent sheet severing units.", "A further object of the invention is to provide a novel and improved mechanism for adjusting the position of a blade relative to its holder in a severing unit wherein only the end faces of the holder are accessible when the severing unit is ready for use.", "An additional object of the invention is to provide a novel and improved holder for use in the above outlined severing apparatus.", "Still another object of the invention is to provide a simple, compact and inexpensive blade adjusting mechanism which can be installed in existing types of sheet severing apparatus as a superior substitute for heretofore known adjusting mechanisms.", "A further object of the invention is to provide an adjusting mechanism which can be reached and manipulated without necessitating even partial dismantling of the severing apparatus.", "Another object of the invention is to provide an adjusting mechanism which renders it possible to place two or more discrete severing units into immediate or very close proximity to each other without adversely affecting the accessibility of the adjusting mechanism.", "A further object of the invention is to provide a novel and improved method of installing the adjusting mechanism in the holder for the blade of a mobile knife in a paper sheet cutting apparatus.", "An additional object of the invention is to provide a production line for stationery products which embodies one or more adjusting mechanisms of the above outlined character.", "SUMMARY OF THE INVENTION The invention is embodied in an apparatus for severing sheet-like materials (e.g., stacks of paper sheets).", "The improved apparatus comprises at least one severing unit including a first knife and a second knife, and means for moving one of the knives relative to the other knife whereby the knives sever one or more sheets which are placed between them while the knives are spaced apart from each other.", "The first knife comprises a blade having an elongated cutting edge and a surface extending along the cutting edge, a holder having an elongated side face adjacent the surface of the blade and at least one end face at one end of the side face, means (e.g., bolts remote from the cutting edge) for connecting the blade to the holder, and means for adjusting the blade relative to the holder, namely for adjusting the location of the cutting edge relative to the second knife (e.g., in order to compensate for wear).", "The adjusting means comprises a plurality of displacing elements which are recessed into the side face and are movable transversely of and against the surface of the blade (preferably between the cutting edge and the connecting means), a moving element for each of the displacing elements, and devices for transmitting motion between the moving elements and the respective displacing elements.", "The moving elements are accessible at the at least one end face of the holder and are movable in the holder in substantial parallelism with the cutting edge of the blade.", "The one knife is preferably the first knife of the at least one severing unit, and the second knife of such unit is preferably a stationary counterknife.", "The moving elements can include or constitute pressure transmitting bolts having axes which are at least substantially parallel to the cutting edge of the blade.", "Such moving elements are preferably provided with external threads and are rotatable in tapped bores or holes of the holder;", "the tapped bores extend inwardly from the at least one end face of the holder and communicate with discrete holes or bores for the corresponding displacing elements.", "The bores or holes for the displacing elements extend at right angles to the surface of the blade and hence at right angles to the side face of the holder.", "Each motion transmitting device can include a wedge which is operative to move the respective displacing element in its hole or bore in response to movement of the corresponding moving element in its hole or bore.", "Each wedge has a first surface which is inclined relative to the surface of the blade, and each displacing element has a second surface which is complementary to and abuts the surface of the respective wedge.", "The displacing and moving elements are or can be disposed in a common plane, e.g., in a substantially horizontal plane which is at least substantially normal to the surface of the blade and to the side face of the holder.", "The holder preferably includes a second end face at the other end of the elongated side face, and the adjusting means preferably further comprises at least one additional displacing element which is recessed into the side face of the holder and is movable transversely of and against the surface of the blade, an additional moving element which is accessible at the second end face of the holder and is movable in the holder in substantial parallelism with the cutting edge, and an additional device for transmitting motion from the additional moving element to the additional displacing element.", "The side face of the holder includes a first half which is adjacent the at least one end face and a second half which is adjacent the second end face.", "The at least one additional displacing element is recessed into the second half and the displacing elements which receive motion from moving elements that are accessible at the at least one end face of the holder are recessed into the first half of the side face.", "The arrangement is preferably such that each moving element at the at least one end face and the associated motion transmitting device and displacing element are mirror images of a moving element which is accessible at the second end face and of the associated motion transmitting device and displacing element.", "The apparatus preferably further comprises at least one additional severing unit having a first knife and a second knife.", "One knife of the at least one additional severing unit is connected to and is movable by the moving means for the one knife of the at least one severing unit.", "The severing units are preferably closely or immediately adjacent each other.", "The cutting edge of the blade of the first knife of the at least one severing unit is preferably parallel to the cutting edge of the blade of the one knife of the at least one additional severing unit.", "The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims.", "The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.", "BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic side elevational view of a severing apparatus with a plurality of severing units each of which embodies one form of the invention;", "FIG. 2 is a side elevational view of one of the severing units, substantially as seen in the direction of arrow II in FIG. 1;", "FIG. 3 is an end elevational view of the severing unit as shown in FIG. 2;", "and FIG. 4 is a fragmentary sectional view substantially as seen in the direction of arrows from the line IV--IV in FIG. 2. DESCRIPTION OF PREFERRED EMBODIMENTS The severing apparatus 1 of FIG. 1 can be used in a production line for writing pads, exercise pads, steno pads and analogous stationery products.", "The apparatus 1 is designed to simultaneously sever a stack of overlapping sheets 2 into a plurality of smaller sections in the form of strips or the like extending at right angles to the plane of FIG. 1. To this end, the apparatus 1 comprises a plurality of rather closely adjacent parallel severing units 3 each having a mobile first knife 6, 7 and a stationary second knife or counterknife 4 beneath the respective mobile knife.", "The mobile knives have elongated parallel holders 7 which are affixed to or form part of a common moving member 8 serving to move the holders 7 up and down away from and toward the respective counterknives 4.", "A sheet 2 or a stack of sheets 2 is introduced between the stationary counterknives 4 and the lifted elongated blades 6 of the mobile knives before the holders 7 are caused to descend whereby the cutting edges 6a of the blades 6 cooperate with the cutting edges 4a of the counterknives 4 to sever the sheet or sheets 2.", "The means for moving the member 8 up and down in the frame of the severing apparatus 1 can comprise one or more fluid-operated cylinder and piston assemblies or the like, not shown.", "FIG. 1 further shows hold-down devices 9 which are mounted on the member 8 and cooperate with the adjacent counterknives 4 to prevent shifting of the sheet or sheets 2 in the course of a severing operation.", "The details of one severing unit 3 are shown in FIGS. 2, 3 and 4.", "This unit comprises an elongated knife blade holder 7 having two end faces 17, 18 which are accessible when the holder 7 is mounted on the member 8 in close proximity to the holder or holders 7 of one or two neighboring severing units 3, and an elongated upright side face 7a which abuts the surface 6b of the blade 6.", "The cutting edge 6a of the blade 6 extends all the way between its end faces which may but need not be coplanar with the respective end faces 17, 18 of the holder 7.", "The means for connecting the blade 6 to the holder 7 comprises a row of parallel externally threaded bolts 107 which are remote from the cutting edge 6a and extend at right angles to the planes of the surface 6b and side face 7a.", "The blade 6 is at least slightly flexible in the region between the shanks of the connecting bolts 107 and the cutting edge 6a, and the mechanism for adjusting the blade 6 and hence the cutting edge 6a relative to the corresponding counterknife 4 is installed in the holder 7 and includes moving elements in the form of externally threaded bolts 12 which are accessible at the two end faces 17 and 18.", "To this end, the holder 7 is provided with sets of parallel tapped bores or holes 13 which are parallel to the side face 7a and extend in substantial parallelism with the cutting edge 6a.", "The external threads of the moving elements or bolts 12 are in mesh with the internal threads of the holder 7, and the heads of the elements 12 are accessible at the respective end faces 17, 18 so that a screwdriver or another elementary tool can be employed to move the elements 12 axially and to thus change the axial positions of associated pin-shaped cylindrical displacing elements 11 which are recessed into the side face 7a of the holder 7 and engage the adjacent surface 6b of the blade 6 between the bolts 107 and the cutting edge 6a.", "The adjusting mechanism for the blade 6 further comprises wedge-shaped motion transmitting devices 14 which are reciprocable in the bores or holes 13 for the respective moving elements 12 and have surfaces 14a inclined relative to the side face 7a and abutting complementary surfaces 11a at the inner ends of the displacing elements 11.", "The elements 11 are reciprocable in bores or holes 16 which are machined into or are otherwise formed in the holder 7 and are normal to the side face 7a (and hence to the surface 6b when the blade 6 is properly connected to the holder by bolts 107).", "The moving elements 12, the displacing elements 11, and the motion transmitting devices 14 are disposed in a common horizontal plane which is normal to the side face 7a.", "FIG. 2 shows that the blade 6 is adjustable by a set of six equidistant displacing elements 11.", "The bores or holes 16 for the three right-hand displacing elements 11 are provided in the right-hand half of the side face 7a, namely in that half which is adjacent the end face 18, and the bores or holes 16 for the other three displacing elements 11 are provided in the left-hand half of the side face 7a (i.e., in that half which is adjacent the end face 17).", "The number of bores or holes 16 in the one half of the side face 7a may but need not equal the number of holes or bores 16 in the other half of such side face.", "It is further possible to provide moving elements 12 only at one longitudinal end of the holder 7 if the number of displacing elements 11 is relatively small (i.e., if the blade 6 is relatively short) and/or if the end face 17 or 18 is not accessible when the respective severing unit 3 is assembled with one or more additional severing units 3 to form part of the apparatus 1.", "The operation of the adjusting mechanism will be readily understood upon perusal of the preceding description.", "Thus, rotation of the moving elements 12 relative to the holder 7 in a direction to move the elements 12 deeper into the respective bores or holes 13 entails a corresponding movement of the associated wedge-like motion transmitting devices 14 whereby the inclined surfaces 14a of the devices 14 move relative to the adjacent surfaces 11a and move the elements 11 in the respective bores or holes 16 so that the corresponding portions of the cutting edge 6a are moved away from the side face 7a of the holder.", "If the moving elements 12 are rotated in the opposite direction, innate elasticity of the blade 6 causes the cutting edge 6a to move nearer to the side face 7a of the holder 7.", "Each bore or hole 16 can extend all the way through the holder 7, i.e., from the side face 7a to the side face 7b (see FIG. 4).", "An important advantage of the improved severing units 3 and of their adjusting mechanisms is that the heads of the moving elements 12 are accessible at the end faces 17 and 18 of the respective holders 7.", "Such end faces are normally accessible to the working ends of tools even if the severing units 3 are installed in immediate or close proximity to each other.", "Therefore, the positions of the cutting edges 6a relative to the associated holders 7 and counterknives 4 can be adjusted without necessitating even partial dismantling of the severing apparatus 1.", "Such adjustments can be carried out irrespective of the mutual spacing of neighboring severing units 3, i.e., such spacing can be selected exclusively in dependency on the desired width of strips or stacks of strips which are to be obtained in response to each lowering of the member 8.", "The latter is connected to the holders 6 by sets of bolts 108.", "Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the appended claims." ]
This invention relates to the fabrication of multilayer printed circuit boards with interconnections between the layers. BACKGROUND OF THE INVENTION Multilayer printed circuit boards have been known for some time, but the art has developed a variety of problems. See, for example, U.S. Pat. Nos. 3,934,335 and 4,211,603 and the problems discussed therein which include delamination, layer misalignment, smearing of dielectric material onto circuitry layers and non-uniformly-sized and ill-defined vias, or holes through dielectric layers, for interconnection between layers of circuitry, as well as an inability to produce vias less than about 15 mils in diameter. There have been attempts to solve such problems, the attempts resulting in the development of some novel solutions, but the solutions themselves have often resulted in processes which are complex, time-consuming and relatively expensive. For example, in U.S. Pat. No. 3,934,335 there is disclosed a complex method of fabricating multilayer printed circuit boards involving forming conductive patterns by electrolessly plating a conductive metal onto a layer of dielectric which has first had its surface pitted by treatment with a caustic solution, then sensitized by treatment with successive solutions of tin and palladium salts. As another example, polymer thick film (PTF) technology is used for fabrication of a two conductive layer LED display device in U.S. Pat. No. 4,305,204, which discloses a time-consuming printing process for a double-printed dielectric layer over an etched conductor pattern, the dielectric comprising an epoxy resin and requiring a partial heat cure after the first printing and a full heat cure after the second printing; thereafter, a conductive PTF layer is silkscreened over the double-printed laminated dielectric layer and all three layers are further heat cured. Thus, there exists a need for a multilayer printed circuit board fabrication process which is simple, fast, inexpensive and is capable of producing boards with sharply defined and uniformly sized vias substantially smaller than 15 mils in diameter and which will resist delamination and short circuiting under operating conditions. This need and other advantages are accomplished by the present invention, which is summarized and described in detail below. SUMMARY OF THE INVENTION According to the present invention, there is provided a method for fabricating multilayer printed circuit boards with points of interconnection between conductive layers and through intervening dielectric layers comprising a multi-step process as follows: (1) forming a conductive pattern on a non-conducting substrate such as epoxy by applying to the substrate a layer of conductive polymer thick film in a predetermined pattern and curing the film, (2) applying a layer of photoimageable photopolymerizable dielectric material over the cured conductive film, (3) forming a dielectric layer defining vias, or holes for interconnection of circuitry layers through the dielectric layer, by selectively exposing in a predetermined pattern the layer of photoimageable photopolymerizable dielectric material (4) forming vias through the layer of dielectric material by removing those portions of dielectric material corresponding to the desired vias and (5) forming a second conductor pattern on the dielectric layer and simultaneously forming conductive interconnections between the first and second conductor patterns and through the dielectric layer between the conductor patterns by applying a second conductive polymer thick film to the dielectric layer in a predetermined pattern whereby the vias or through holes are also coated on the insides thereof by the conductive polymer thick film, and curing said film. Should more than two conductive layers by desired, steps (2) through (5) may be repeated. The process of the present invention is also useful for forming multilayer printed circuit board with multiple layers on both sides of a substantially planar substrate by going through the same process outlined above, but forming the layers on both sides of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of an exemplary substantially planar non-conductive substrate. FIG. 2 is a cross-sectional view of the substrate of FIG. 1 showing a layer of conductive polymer thick film applied to one side thereof in an exemplary predetermined pattern. FIG. 3 is a cross-sectional view of the substrate of FIG. 1 showing a layer of photoimageable photopolymerizable dielectric material coated over the layer of conductive polymer thick film shown in FIG. 2. FIG. 4 is a cross-sectional view of the substrate of FIG. 1 showing the formulation of a dielectric layer defining vias by selective exposure of the layer of photoimageable photopolymerizable dielectric material. FIG. 5 is a cross-sectional view of the substrate of FIG. 1 showing exemplary vias created through the dielectric layer by removal of those portions of dielectric material corresponding to the vias. FIG. 6 is a cross-sectional view of the substrate of FIG. 1 showing application of an additional layer of conductive polymer thick film, the film coating the inside of the vias and making interconnections between conductive layers. FIG. 7 is a cross-sectional view of the substrate of FIG. 1 showing application of a soldermask to the outermost conductive layer. FIG. 8 is a cross-sectional view of the substrate of FIG. 1 showing deposition of electroless nickel plating over the outermost conductive layer. FIG. 9 is a cross-sectional view of the substrate of FIG. 1 showing the process of the present invention as applied to both sides of the substrate. The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, wherein like numerals indicate the same elements, FIG. 1 depicts an exemplary nonconducting substrate 1 which is typically a substantially planar monolithic configuration. Virtually any material that is nonconductive will suffice for the substrate, the only constraint being that it have sufficient tensile strength to support multiple layers and components and the ability to withstand the normal environment present under operating conditions of printed board circuitry. Preferred classes of substrate material include polymers, alumina, ceramics, paper and wood. Epoxy resin-impregnated glass cloth such as that known in the art as FR-4 is the most preferred class of substrate material. The initial step in the fabrication process of the present invention comprises forming a conductor pattern on the substrate, illustrated in FIG. 2. The conductor pattern is formed by applying a conductive polymer thick film 2 to the substrate 1 in a predetermined pattern corresponding to a desired electrical circuit, the film being applied from about 0.2 mil to about 1.5 mils in thickness. In general, any metal dispersed in a polymer will do as long as it can conduct electricity adequately for good performance under normal operating conditions. An exemplary commercially available material is Amicon 932-62-1, an epoxy resin with silver dispersed therein and manufactured by Amicon Corporation of Lexington, Mass. Application of the conductive polymer thick film may be made by silkscreening, printing, ink jet and pen plotter methods. Of these, silkscreening is preferred, using a silk screener with a stainless steel mesh of 80 to 400. Curing the conductive polymer thick film 2 is accomplished by a convection oven, an infrared oven or a vapor cure. For example, using a convection oven and the conductive polymer thick film Amicon 932-62-1, cures should be in the range of 100° C. to 180° C. and from 20 to 60 minutes. The next step in the fabrication process comprises applying a layer of either "negative" acting or "positive" acting photoimageable photopolymerizable dielectric or insulator material over the polymer thick film conductor pattern. The application and development of "negative" acting material is best seen schematically in FIGS. 3-5. Referring to FIG. 3, the dielectric material 3 is laid down in contact with the conductor pattern 2 and the substrate 1 to be polymerized by a light source (not shown). If the material is "positive" acting, after application, exposure to a light source causes rupture of the polymeric bonds and reversion of the material to an essentially monomeric state. Of the two types of material, "negative" acting is preferred. Preferred classes of such material are epoxy resins and acrylic resins. An example of the "negative" acting photoimageable photopolymerizable dielectric material is Dynachem Laminar RM, an acrylicbased dry film soldermask made by Dynachem Corporation of Irvine, Calif. The unexposed dielectric layer 3 is typically applied in a layer from about 0.1 to about 10 mils in thickness by silkscreening, printing, dip coating, spray coating, roller coating, curtain coating, dry film lamination and casting techniques, all well known in the art. Next, referring to FIG. 4, the unexposed dielectric layer 3 is selectively exposed to a light source (not shown) by masking it in a predetermined pattern corresponding to the desired location of holes through the dielectric for points of interconnection between a given conductive layer and the next succeeding conductive layer; such through holes are commonly referred to in the art as "vias" and the term is used here in that same sense. Upon exposure, the unmasked portions of, for example, "negative" acting dielectric are polymerized into a dielectric layer 4 which defines vias by surrounding unexposed (and so nonpolymerized) portions 5 and 6. Masking is accomplished by interposition of a stencil of some sort between the light source and the dielectric layer. The polymerizing light may comprise virtually any wavelengths, but the most common and preferred are those in the ultraviolet range, which may be provided by commercially available circuit board exposure equipment such as that made by Colight, Inc. of Minneapolis, Minn. Referring now to FIGS. 4 and 5, vias 7 and 8 are actually formed by removal of those portions of dielectric material 5 and 6 corresponding to the vias, shown in the drawings as removal of unexposed non-polymerized dielectric material. Removal is typically accomplished by contact with a solvent or plasma etching. By "solvent" is meant any liquid which is capable of forming a partial or complete solution with the unwanted dielectric material so as to effect removal thereof. For Dynachem Laminar RM, an appropriate solvent is a solution of 1% potassium carbonate. In the event a "positive" acting photoimageable photopolymerizable dielectric material is selected, the material would be applied in a layer and masked so as to define vias, the exposure to a light source causing a photolytic reaction at the via sites, thus forming removable monomer at those sites. Upon removal of those monomeric portions corresponding to vias, the vias are formed. After formulation of the dielectric layer 4, it may optionally be subjected to a heat cure to complete the cure, thereby enhancing its stability and adhesion to both the substrate 1 and to the first conductive polymer thick film 2. Curing temperatures and times will vary widely depending upon the particular dielectric material used. Either an infrared oven or a convection oven may be used; suitable curing temperatures and times for Dynachem Laminar RM in a convection oven are 140°-160° C. and 35-45 minutes. Because of the much sharper definition produced by the photoimaging process, extremely small vias that are highly uniform in size with sharply defined boundaries are possible. For example, vias having diameters from 1 to 5 mils may be consistently produced with tolerances of ±0.1 mil. This advantage, coupled with finer line and space parameters for the conductor patterns, make possible the production of multilayer printed circuit boards of much higher density circuitry than is obtainable with conventional processes. The final step in the creation of the simplest multilayer circuitry unit (comprising two circuitry layers separated by a dielectric layer with points of interconnection between the two circuits and through the dielectric) according to the present invention is the formation of another conductor pattern on the dielectric layer and the simultaneous formation of conductive interconnections between circuitry and through the dielectric, shown schematically in FIG. 6. This step is accomplished by applying in a predetermined pattern another conductive polymer thick film 10 in the same thickness range and by any of the same methods discussed above. Note that this step not only forms another conductor pattern but also coats vias 7 and 8 with conductive material schematically shown as 10a, thereby forming points of interconnection 12 and 14 between conductive layers 2 and 10. FIG. 7 shows the addition of a soldermask or covercoat 15 which is desireably added to the outermost conductor pattern 10. To improve solderability, the outermost circuitry layer(s) and points of interconnection associated therewith are advantageously plated with nickel by electroless plating techniques well known in the art. The plating should be about 100 microinches thick, and as taught by Baudrand in "Advantages of Electroless Nickel Plating of Hybrid Circuits," 29 Elecri.onics 20 (1983). Alternatively, the plating may be accomplished prior to addition of the soldermask in order to improve conductivity. FIG. 8 showns an exemplary layer 16 of electroless nickel plate on the outermost conductor pattern 10. All of the above steps may of course be repeated in the same order to create multiples of the simplest multilayer circuitry unit up to a practical maximum of three to five per side of the substrate. Instead of building up layers on a single side of the substrate, a similar build-up may be accomplished by applying the process of the present invention to both sides of the substrate with the same process, FIG. 9 showing an exemplary cross-sectional view of the result of such a process. The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
A method of fabricating multilayer printed circuit boards using polymer thick film technology is disclosed which utilizes photoimageable dielectric material between conductive polymer thick film layers and which is capable of producing extremely small and uniformly-sized vias.
Briefly describe the main idea outlined in the provided context.
[ "This invention relates to the fabrication of multilayer printed circuit boards with interconnections between the layers.", "BACKGROUND OF THE INVENTION Multilayer printed circuit boards have been known for some time, but the art has developed a variety of problems.", "See, for example, U.S. Pat. Nos. 3,934,335 and 4,211,603 and the problems discussed therein which include delamination, layer misalignment, smearing of dielectric material onto circuitry layers and non-uniformly-sized and ill-defined vias, or holes through dielectric layers, for interconnection between layers of circuitry, as well as an inability to produce vias less than about 15 mils in diameter.", "There have been attempts to solve such problems, the attempts resulting in the development of some novel solutions, but the solutions themselves have often resulted in processes which are complex, time-consuming and relatively expensive.", "For example, in U.S. Pat. No. 3,934,335 there is disclosed a complex method of fabricating multilayer printed circuit boards involving forming conductive patterns by electrolessly plating a conductive metal onto a layer of dielectric which has first had its surface pitted by treatment with a caustic solution, then sensitized by treatment with successive solutions of tin and palladium salts.", "As another example, polymer thick film (PTF) technology is used for fabrication of a two conductive layer LED display device in U.S. Pat. No. 4,305,204, which discloses a time-consuming printing process for a double-printed dielectric layer over an etched conductor pattern, the dielectric comprising an epoxy resin and requiring a partial heat cure after the first printing and a full heat cure after the second printing;", "thereafter, a conductive PTF layer is silkscreened over the double-printed laminated dielectric layer and all three layers are further heat cured.", "Thus, there exists a need for a multilayer printed circuit board fabrication process which is simple, fast, inexpensive and is capable of producing boards with sharply defined and uniformly sized vias substantially smaller than 15 mils in diameter and which will resist delamination and short circuiting under operating conditions.", "This need and other advantages are accomplished by the present invention, which is summarized and described in detail below.", "SUMMARY OF THE INVENTION According to the present invention, there is provided a method for fabricating multilayer printed circuit boards with points of interconnection between conductive layers and through intervening dielectric layers comprising a multi-step process as follows: (1) forming a conductive pattern on a non-conducting substrate such as epoxy by applying to the substrate a layer of conductive polymer thick film in a predetermined pattern and curing the film, (2) applying a layer of photoimageable photopolymerizable dielectric material over the cured conductive film, (3) forming a dielectric layer defining vias, or holes for interconnection of circuitry layers through the dielectric layer, by selectively exposing in a predetermined pattern the layer of photoimageable photopolymerizable dielectric material (4) forming vias through the layer of dielectric material by removing those portions of dielectric material corresponding to the desired vias and (5) forming a second conductor pattern on the dielectric layer and simultaneously forming conductive interconnections between the first and second conductor patterns and through the dielectric layer between the conductor patterns by applying a second conductive polymer thick film to the dielectric layer in a predetermined pattern whereby the vias or through holes are also coated on the insides thereof by the conductive polymer thick film, and curing said film.", "Should more than two conductive layers by desired, steps (2) through (5) may be repeated.", "The process of the present invention is also useful for forming multilayer printed circuit board with multiple layers on both sides of a substantially planar substrate by going through the same process outlined above, but forming the layers on both sides of the substrate.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of an exemplary substantially planar non-conductive substrate.", "FIG. 2 is a cross-sectional view of the substrate of FIG. 1 showing a layer of conductive polymer thick film applied to one side thereof in an exemplary predetermined pattern.", "FIG. 3 is a cross-sectional view of the substrate of FIG. 1 showing a layer of photoimageable photopolymerizable dielectric material coated over the layer of conductive polymer thick film shown in FIG. 2. FIG. 4 is a cross-sectional view of the substrate of FIG. 1 showing the formulation of a dielectric layer defining vias by selective exposure of the layer of photoimageable photopolymerizable dielectric material.", "FIG. 5 is a cross-sectional view of the substrate of FIG. 1 showing exemplary vias created through the dielectric layer by removal of those portions of dielectric material corresponding to the vias.", "FIG. 6 is a cross-sectional view of the substrate of FIG. 1 showing application of an additional layer of conductive polymer thick film, the film coating the inside of the vias and making interconnections between conductive layers.", "FIG. 7 is a cross-sectional view of the substrate of FIG. 1 showing application of a soldermask to the outermost conductive layer.", "FIG. 8 is a cross-sectional view of the substrate of FIG. 1 showing deposition of electroless nickel plating over the outermost conductive layer.", "FIG. 9 is a cross-sectional view of the substrate of FIG. 1 showing the process of the present invention as applied to both sides of the substrate.", "The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.", "DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, wherein like numerals indicate the same elements, FIG. 1 depicts an exemplary nonconducting substrate 1 which is typically a substantially planar monolithic configuration.", "Virtually any material that is nonconductive will suffice for the substrate, the only constraint being that it have sufficient tensile strength to support multiple layers and components and the ability to withstand the normal environment present under operating conditions of printed board circuitry.", "Preferred classes of substrate material include polymers, alumina, ceramics, paper and wood.", "Epoxy resin-impregnated glass cloth such as that known in the art as FR-4 is the most preferred class of substrate material.", "The initial step in the fabrication process of the present invention comprises forming a conductor pattern on the substrate, illustrated in FIG. 2. The conductor pattern is formed by applying a conductive polymer thick film 2 to the substrate 1 in a predetermined pattern corresponding to a desired electrical circuit, the film being applied from about 0.2 mil to about 1.5 mils in thickness.", "In general, any metal dispersed in a polymer will do as long as it can conduct electricity adequately for good performance under normal operating conditions.", "An exemplary commercially available material is Amicon 932-62-1, an epoxy resin with silver dispersed therein and manufactured by Amicon Corporation of Lexington, Mass.", "Application of the conductive polymer thick film may be made by silkscreening, printing, ink jet and pen plotter methods.", "Of these, silkscreening is preferred, using a silk screener with a stainless steel mesh of 80 to 400.", "Curing the conductive polymer thick film 2 is accomplished by a convection oven, an infrared oven or a vapor cure.", "For example, using a convection oven and the conductive polymer thick film Amicon 932-62-1, cures should be in the range of 100° C. to 180° C. and from 20 to 60 minutes.", "The next step in the fabrication process comprises applying a layer of either "negative"", "acting or "positive"", "acting photoimageable photopolymerizable dielectric or insulator material over the polymer thick film conductor pattern.", "The application and development of "negative"", "acting material is best seen schematically in FIGS. 3-5.", "Referring to FIG. 3, the dielectric material 3 is laid down in contact with the conductor pattern 2 and the substrate 1 to be polymerized by a light source (not shown).", "If the material is "positive"", "acting, after application, exposure to a light source causes rupture of the polymeric bonds and reversion of the material to an essentially monomeric state.", "Of the two types of material, "negative"", "acting is preferred.", "Preferred classes of such material are epoxy resins and acrylic resins.", "An example of the "negative"", "acting photoimageable photopolymerizable dielectric material is Dynachem Laminar RM, an acrylicbased dry film soldermask made by Dynachem Corporation of Irvine, Calif.", "The unexposed dielectric layer 3 is typically applied in a layer from about 0.1 to about 10 mils in thickness by silkscreening, printing, dip coating, spray coating, roller coating, curtain coating, dry film lamination and casting techniques, all well known in the art.", "Next, referring to FIG. 4, the unexposed dielectric layer 3 is selectively exposed to a light source (not shown) by masking it in a predetermined pattern corresponding to the desired location of holes through the dielectric for points of interconnection between a given conductive layer and the next succeeding conductive layer;", "such through holes are commonly referred to in the art as "vias"", "and the term is used here in that same sense.", "Upon exposure, the unmasked portions of, for example, "negative"", "acting dielectric are polymerized into a dielectric layer 4 which defines vias by surrounding unexposed (and so nonpolymerized) portions 5 and 6.", "Masking is accomplished by interposition of a stencil of some sort between the light source and the dielectric layer.", "The polymerizing light may comprise virtually any wavelengths, but the most common and preferred are those in the ultraviolet range, which may be provided by commercially available circuit board exposure equipment such as that made by Colight, Inc. of Minneapolis, Minn.", "Referring now to FIGS. 4 and 5, vias 7 and 8 are actually formed by removal of those portions of dielectric material 5 and 6 corresponding to the vias, shown in the drawings as removal of unexposed non-polymerized dielectric material.", "Removal is typically accomplished by contact with a solvent or plasma etching.", "By "solvent"", "is meant any liquid which is capable of forming a partial or complete solution with the unwanted dielectric material so as to effect removal thereof.", "For Dynachem Laminar RM, an appropriate solvent is a solution of 1% potassium carbonate.", "In the event a "positive"", "acting photoimageable photopolymerizable dielectric material is selected, the material would be applied in a layer and masked so as to define vias, the exposure to a light source causing a photolytic reaction at the via sites, thus forming removable monomer at those sites.", "Upon removal of those monomeric portions corresponding to vias, the vias are formed.", "After formulation of the dielectric layer 4, it may optionally be subjected to a heat cure to complete the cure, thereby enhancing its stability and adhesion to both the substrate 1 and to the first conductive polymer thick film 2.", "Curing temperatures and times will vary widely depending upon the particular dielectric material used.", "Either an infrared oven or a convection oven may be used;", "suitable curing temperatures and times for Dynachem Laminar RM in a convection oven are 140°-160° C. and 35-45 minutes.", "Because of the much sharper definition produced by the photoimaging process, extremely small vias that are highly uniform in size with sharply defined boundaries are possible.", "For example, vias having diameters from 1 to 5 mils may be consistently produced with tolerances of ±0.1 mil.", "This advantage, coupled with finer line and space parameters for the conductor patterns, make possible the production of multilayer printed circuit boards of much higher density circuitry than is obtainable with conventional processes.", "The final step in the creation of the simplest multilayer circuitry unit (comprising two circuitry layers separated by a dielectric layer with points of interconnection between the two circuits and through the dielectric) according to the present invention is the formation of another conductor pattern on the dielectric layer and the simultaneous formation of conductive interconnections between circuitry and through the dielectric, shown schematically in FIG. 6. This step is accomplished by applying in a predetermined pattern another conductive polymer thick film 10 in the same thickness range and by any of the same methods discussed above.", "Note that this step not only forms another conductor pattern but also coats vias 7 and 8 with conductive material schematically shown as 10a, thereby forming points of interconnection 12 and 14 between conductive layers 2 and 10.", "FIG. 7 shows the addition of a soldermask or covercoat 15 which is desireably added to the outermost conductor pattern 10.", "To improve solderability, the outermost circuitry layer(s) and points of interconnection associated therewith are advantageously plated with nickel by electroless plating techniques well known in the art.", "The plating should be about 100 microinches thick, and as taught by Baudrand in "Advantages of Electroless Nickel Plating of Hybrid Circuits,"", "29 Elecri.", "onics 20 (1983).", "Alternatively, the plating may be accomplished prior to addition of the soldermask in order to improve conductivity.", "FIG. 8 showns an exemplary layer 16 of electroless nickel plate on the outermost conductor pattern 10.", "All of the above steps may of course be repeated in the same order to create multiples of the simplest multilayer circuitry unit up to a practical maximum of three to five per side of the substrate.", "Instead of building up layers on a single side of the substrate, a similar build-up may be accomplished by applying the process of the present invention to both sides of the substrate with the same process, FIG. 9 showing an exemplary cross-sectional view of the result of such a process.", "The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow." ]
CROSS-REFERENCE This patent application is related to the co-pending U.S. patent application Ser. No. 08/579,897, entitled, A MULTI-PROCESSOR DATA PROCESSING SYSTEM WITH MULTIPLE SECOND LEVEL CACHES MAPABLE TO ALL OF ADDRESSABLE MEMORY, filed concurrent herewith by Bauman et al., and which is assigned to the assignee of the present invention. BACKGROUND 1. Field of the Invention This invention generally relates to cache architectures for data processing systems and more particularly to a shared memory multi-processor data processing system having a plurality of second-level caches, where each of the second-level is comprised of a separate instruction second-level cache and a separate operand second-level cache. 2. Description of the Prior Art Multilevel storage hierarchies have been used to enhance the performance of data processing systems. Smaller higher speed memories, often called cache memories, are located in the storage access path between an instruction processor and the system's main memory. Instructions and operands present in the cache memories can be referenced more quickly than instructions and operands located in the system's main memory. Various cache structures have been used to gain assorted advantages from cache memories. U.S. Pat. No. 5,386,547 to Jouppi shows a cache architecture within a single processor data processing system. The cache architecture of Jouppi shows what are referred to by Jouppi as first and second-level caches. The first and second-level caches swap data, thereby seeking to gain some level of associativity from a direct-mapped cache. Jouppi also shows multi-level cache architecture with separate instruction and operand caches. The objective sought for having separate instruction and operand caches is to separate the application of the cache replacement algorithms to each of the separate caches. U.S. Pat. No. 5,423,016 to Tsuchiya et al, illustrates a store-through first-level cache that is split into a separate instruction and operand section. The second-level cache stores both instructions and operands and is shared between multiple processors. Therefore, the second-level cache of Tsuchiya makes no distinction between instructions and operands, and its caching algorithms are the same for both types of references. SUMMARY OF THE INVENTION The present invention overcomes the shortcomings of the prior art by providing a multiprocessor data processing system that has store-through first-level caches associated with each of the processors, each of the first-level caches having a separate instruction cache and operand cache, and a second-level cache that is shared between the processors where the second-level cache also has a separate instruction cache and operand cache. The Jouppi cache architecture does not provide a workable solution for a multiprocessor shared memory data processing system. Jouppi does not disclose how cache coherency could be maintained in a multiprocessor shared memory system. In addition, Jouppi has a high overhead cost associated with swapping data between the first-level and second-level cache. The Tsuchiya cache architecture illustrates a multi-level cache architecture for a multiprocessor data processing system. However, Tsuchiya has many remote interfaces required for second-level cache access, and additionally, mixes instructions and operands in the second-level cache. A primary objective of the present invention is to improve the cost/performance ratio for a multi-processor data processing system. This objective and others are achieved by effectively matching the appropriate cache algorithms and technology to the different characteristics associated with instructions and operands in a second-level cache. The characteristics associated with instruction references as compared to operand references, relative to a second-level cache that supports store-through first-level caches, are very different. First, instruction references are always read operations to the second-level cache. Instruction references also conform closely to the principle of locality of reference. Instructions are rarely modified by the instruction reference generator, and therefore have a backup copy in memory. As a result, the second-level cache does not need to provide additional error correction logic for instructions. Eliminating error correction logic for instructions reduces access time. Operand references can be both read and write operations. Relative to the second-level cache, a significant majority of the operations are write operations where there are store-through first-level caches. Operand references to the second-level cache do not benefit as well as do instructions from having a large cache. This is because operands do not follow the locality of reference principle as well as instructions. The main benefit that the second-level cache provides for operands is the ability to quickly handle the write operations that flow through the first-level caches and to share the modified data with other processors in the multiprocessor environment. Because most second-level caches operate in a strife-in mode, the second-level cache has the most recent updated copy of the operand and there is no backup copy available in the system memory. Therefore, error correction is required to ensure reliable operation. Historically, cache RAM structures have been implemented in two ways: one is using discrete SRAM devices that are somewhat limited in functionality and very limited in interconnect options, but have good density and cost factors; and the second way is using embedded RAM structures within ASICs. The embedded RAM structures have very good functionality characteristics and minimal interconnect constraints, but have very high cost factors for a given density. A major advantage of SRAM devices is that they are available in very large capacities, and as a result, when used in a cache design, they provide for having a very high cache hit rate. However, in order to minimize package size and maximize density, many SRAMs that are used in cache systems have one set of data lines for both read and write data. As a result, they operate using bi-directional bus techniques, whereby dead cycles are inserted when changing bus direction (e.g., changing from a read direction to a write direction). The dead cycles slow down system performance. In contrast, the embedded RAMs within an ASIC have very good interconnection options because of their inherent dense routing capability within the ASIC. Therefore, the embedded RAMs have separate data read and write lines and no dead cycles are required to change bus direction as in the SRAM devices. In addition, embedded RAMs usually have faster access times because they are physically closer to the logic that they interface with. The embedded RAMs have a cost disadvantage as compared with the SRAM devices because they are unique designs with limited volume for each application. The result of the above is that the characteristics associated with instructions map very well to SRAM devices. The bus can be preconditioned to the read direction and rarely needs to be changed to the write direction. Therefore, dead cycles associated with changing bus direction are greatly reduced. The slower access time associated with the SRAM devices is compensated for by not having to take time to do error correction. In addition, the larger cache size afforded by the SRAMs is more predominant for instructions. The objectives of the present invention are achieved in a multiprocessor data processing system. The system includes a plurality of processors, each having a respective first-level cache. A second-level cache is between the first-level caches and the system memory in the storage hierarchy. The first-level caches are store-through type caches, and are separated into an instruction cache and an operand cache. The second-level cache is a store-in cache that is shared between the processors. The second-level cache is also divided into a separate instruction cache and operand cache. Cache replacement is independent between the instruction second-level cache and the operand second-level cache. In another aspect of the invention, if an instruction read is issued to the second-level cache, it is routed to both the operand second-level cache and to the instruction second-level cache. If an instruction read results in a hit in the operand second-level cache, the block from the operand second-level cache is returned to the requesting processor. This provides data integrity in the case where instructions and operands are intermixed within a block of cached data. A further aspect of the invention has the second-level cache divided into a plurality of segments. Each of the segments is dedicated to caching a predetermined portion of addressable memory. Each of the segments further has an associated, respective operand tag memory and an associated, respective instruction tag memory. Further still, each of the segments has an associated, respective operand memory and an associated, respective instruction memory. Dual second-level cache memories, each having an separate operand cache and instruction cache, define a further aspect of the invention. Each of the second-level cache memories is mappable to all of the system memory. The aforementioned aspects of the invention are also utilized in combination with the dual second-level cache memories. Still other objects and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein only the preferred embodiment of the invention is shown, simply by way of illustration of the best mode contemplated for carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a multi-processor data processing system in which the present invention is embodied; FIG. 2 is a more detailed block diagram of the storage controls and interconnections between the components of the Storage Controllers; FIG. 3 is a block diagram of the addressing between Address ASIC-A and Address ASIC-B and the associated Second-level Cache Storage; FIG. 4 is a block diagram of the components that comprise a Second-level Cache Data Slice; FIG. 5 is a more detailed block diagram of an Address ASIC, a Data ASIC, and a segment of Second-level Cache Storage: FIG. 6 is a block diagram that illustrates the data path between the requesting processors, the second-level cache, and the memory; FIG. 7 is a more derailed diagram of one of the O-SLC segments shown in FIG. 6; FIG. 8 is a more detailed diagram of the I-SLC segments shown in FIG. 5; FIG. 9 is a block diagram of the overall address path of the exemplary system; FIG. 10 is a detailed block diagram of an O-SLC Tag logic circuit; and FIG. 11 is a derailed block diagram of an I-SLC Tag logic circuit. DETAILED DESCRIPTION FIG. 1 is a block diagram of a multi-processor data processing system in which the present invention is embodied. The system includes eight Instruction Processors, IP1, IP2, IP3, IP4, IP5, IP6, IP7, and IP8, each having a dedicated store-through first-level cache. The first-level cache in each of the IPs includes a dedicated instruction cache and a separate dedicated operand cache. Both of the first-level caches are 8K words in size and are organized as 256 sets of four blocks, each block containing 8 words. The operand first-level cache operates as a store-through cache. This means that all write operands are stored into the operand first-level cache if the address is resident there and also passed on to the second-level cache. If the requested write operand is not resident in the operand first-level cache, the operand is not made resident in the operand first-level cache. Blocks of instructions and operands are made resident in the first-level caches on read-misses only. The system of FIG. 1 has two Storage Controllers 12 and 14. Each of Storage Controllers is coupled to four of the IPs. Lines 22, 24, 26, and 28 illustrate the respective point-to-point couplings between the IP1, IP2, IP3, IP4 and Storage Controller 12. Lines 22, 24, 26, and 28 represent the collection of control, data, and address lines between the IPs and the Storage Controller. Lines 32, 34, 36, and 38 represent similar couplings between Storage Controller 14 and IP5, IP6, IP7, and IP8 respectively. Memory requests can also come from components within the I/O Subsystem 1 and I/O Subsystem 2. I/O Subsystem I is coupled to Storage Controller 12 via Line 40, and I/O Subsystem 2 is coupled to Storage Controller 14 via Line 41. Each of the Storage Controllers 12 and 14 has a respective Global SLC 42 and 44. The Global SLCs are described as "global" because each is mapable to the all of system's addressable memory. That is, the entire address range of the addressable memory is cacheable by each of the Global SLCs. The total available addressable memory is designated by Shared Main Memory 48. The Shared Main Memory is comprised of two Memory Subsystems, Memory Subsystem I and Memory Subsystem 2. Global SLC 42 is coupled to Global SLC 44 in a point-to-point fashion as illustrated by Line 52. Line 52 is comprised of data, address, and control lines. Global SLC 42 may be accessed directly by IP1, IP2, IP3, and IP4, and indirectly accessed by IP5, IP6, IP7, and IP8. Similarly, Global SLC 44 may be accessed directly by IP5, IP6, IP7, and IP8, and indirectly by IP1, IP2, IP3, and IP4. If IP1 issues a read request for an address of Memory Subsystem 2 which is neither in IP1's FLC nor in Global SLC 42, the request is forwarded to Global SLC 44. If the requested address is present in Global SLC 44, the data of the requested address is returned to Global SLC 42. If the requested address is a miss in Global SLC 44, the request is forwarded to Memory Subsystem 2. The data is then returned to Global SLC 42. Note that no replacement of data takes place in Global SLC 44 as a result of requests from Global SLC 42. Storage Controller 12 and Global SLC 42 are "local" relative to IP1, IP2, IP3, IP4, and I/O Subsystem 1, and are "remote" relative to IP5, IP6, IP7, IP8, and I/O Subsystem 2. Similarly Storage controller 14 and Global SLC 44 are "local" relative to IP5, IP6, IP7, IP8, and I/O Subsystem 2, and are "remote" relative to IP1, 1P2, IP3, IP4, and I/O Subsystem 1. The Global SLCs may be viewed as dedicated to the requests of their respective local IPs and cooperating in servicing requests from the remote IPs. Global SLC 42 is dedicated to IP1, IP2, IP3, and IP4 in that the SLC storage is dedicated to caching data based on requests from IP1, IP2, IP3, and IP4. Similarly, Global SLC 44 is dedicated to IP5, IP6, IP7, and IP8 in that the SLC storage is dedicated to caching data based on requests from IP5, IP6, IP7, and IP8. Each of the Global SLCs 42 and 44 has a respective, dedicated Instruction SLC (I-SLC) and a dedicated Operand SLC (O-SLC). Global SLC 42 includes I-SLC 62, and O-SLC 64, and Global SLC 44 includes I-SLC 66 and O-SLC 68. Each of the I-SLCs is implemented using high speed external SRAMs. The O-SLCs, on the other hand, are implemented using embedded SRAMs. There are several advantages to separating the instructions from the operands in the SLC. One advantage is that performance is increased. Namely, the storing or reading of operands will not cause an aging of the instructions within the same set address. Operand and instruction contention has therefore been eliminated. A second advantage is that there is speed matching between instructions and operands in the SLC because of different respective requirements. This minimizes SLC latency. The I-SLC, using the external SRAMs has a longer access time. However, error correction is not required for reading instructions from the I-SLC, thereby saving time. Error correction is not required because the instructions in the I-SLC are only copies of that which is maintained in the Main Memory 48. If an error is detected, the copy from the Memory can be re-fetched to correct the error. While the O-SLC does require error correction because it may have the only copy in the system, its access time is shortened because the O-SLC storage is an embedded SRAM. Cache coherency is accomplished with two primary mechanisms. The store-through FLCs use an invalidate mechanism, and the Global SLCs 42 and 44 use a combination of invalidate and tracking which Global SLC was the last to modify cached data ("last-modified"). The FLC invalidate mechanism has two major components: a valid file located in the respective IPs, and the respective Duplicated Tags that are located in the respective Storage Controllers 12 and 14. Note that Duplicate Tags for IP1, IP2, IP3, and IP4 are designated as block 72 in Storage Controller 12 and Duplicate Tags for IP5, IP6, IP7, and IP8 are designated as block 74 in Storage Controller 14. The Duplicated Tags are essentially a copy of the respective FLC tags (not shown). The respective Duplicate Tag is updated when an IP updates its FLC tag, namely, on a read-miss of the FLC. When any local IP performs a write operation, the IP will write to its respective O-FLC if the address is resident and then pass the write operation to the local Storage Controller. The local Storage Controller then searches the local Duplicate Tags. If there is a match, the appropriate IP is notified as to which set and which block needs to be invalidated in its FLC tag. The IP then clears out the associated valid bit in its valid file. This forces the next read by that IP to result in a miss in its FLC and the updated information being fetched from the local Global SLC. If the write address is not present in the FLC, the same invalidation scenario occurs, however, no replacement occurs in the FLC. A technique referred to as last-modified is used by the Global SLCs 42 and 44 to coordinate cache coherency. In order for a Global SLC to allow a write to occur in its storage, it must first be designated as being the Global SLC that last-modified the specified address. Only one Global SLC is allowed to be designated as being the last to modify a particular address. If a Global SLC is already designated as having last-modified an address when a write operation for the address is received, the write operation is processed immediately. If the Global SLC is not designated as having last-modified the address when the write operation is received, then the remote Global SLC is checked to see whether the remote Global SLC has a copy of the data. As the remote Global SLC is checking for a copy, it is also invalidating the remote Duplicate Tags and the remote FLC tags. If the remote Global SLC has a copy of the data, the data is returned to the local SLC and the remote Global SLC invalidates its tags. Therefore, all remote caches have been purged of the requested block. The local Global SLC is then designated as having last-modified the block, and any subsequent write operations from the local processors do not require invalidation to be performed at the remote caches. This method works especially well with instructions because there can be copies in both of the Global SLCs. If both Global SLCs have copies of the block, there is no remote access penalty for an FLC miss. FIG. 2 is a more detailed block diagram of the storage controls and interconnections between the components of the Storage Controllers 12 and 14. Each of the Storage Controllers has two Address ASICs, Address ASIC-A and Address ASIC-B. Address ASIC-A 102 of Storage Controller 12 is directly coupled to Address ASIC-A 104 of Storage Controller 14 via Line 106. Similarly Address ASIC-B 108 is directly coupled to Address ASIC-B 110 via Line 112. Lines 106 and 108 are comprised of unidirectional data, address, and control lines. For the respective Global SLCs 42 and 44, each of the Address ASICs 102, 104, 106, and 108 contain a Tag for 1/2 of the addressable memory space provided by system Memory 48. Specifically, Address ASIC-A 102 contains control and a tag for managing 1/2 of the system's addressable memory for caching in SLC Storage 122, and Address ASIC-B 108 contains control and a tag for managing the other half of the system's addressable memory for caching in SLC Storage 122. Address ASIC-A 104 and Address ASIC-B 110 perform similar functions with respect to SLC Storage 124. Address ASIC-A 102 and Address ASIC-B 108 are directly coupled to IP1, IP2, IP3, IP4, and I/O Subsystem 1 as is respectively shown by Lines 132, 134, 136, 138, and 140. Lines 132, 134, 136, 138 and 140 include unidirectional address, data, and control lines. Address ASIC-A 102 includes Duplicate Tags (not shown) for IP1's FLC and for IP2's FLC, and Address ASIC-B 108 includes Duplicate Tags (not shown) for IP3's FLC and for IP4's FLC. IP5, IP6, IP7, IP8, and I/O Subsystem 2 are directly coupled to Address ASIC-A 104 and Address ASIC-B 110 in a similar manner as shown by Lines 142, 144, 146, 148, and 151). Address ASIC-A 104 contains Duplicate Tags (not shown) for IP5's FLC and for IP6's FLC, and Address ASIC-B 110 contains Duplicate Tags (not shown) for IP7's FLC and for IP8's FLC. Address ASIC-A 102 is directly coupled to Address ASIC-B 108 via Line 162. Line 162 is comprised of unidirectional control lines that provide for transmission of invalidation requests to be processed against the Duplicate Tags that are respectively included in each of Address ASIC-A and Address ASIC-B. Line 164 is a similar coupling between Address ASIC-A 104 and Address ASIC-B 110. Each of the Address ASICs has a respective Operand SLC Tag and a Instruction SLC Tag. Specifically, Address ASIC-A 102 has O-SLC Tag 172 and I-SLC 174, Address ASIC-B 108 has O-SLC Tag 176 and I-SLC Tag 178, Address ASIC A 104 has O-SLC Tag 182 and ISLC Tag 184, and Address ASIC-B 110 has O-SLC Tag 186 and I-SLC Tag 188. O-SLC Tag 172 indicates which addresses are present and valid in half of the O-SLC Data 190 portion of SLC Storage 122, and O-SLC Tag 176 indicates which addresses are present and valid in the other half of the O-SLC Data 190. I-SLC Tag 174 and I-SLC Tag 178 are used similarly for the I-SLC Data 192 portion of SLC Storage 122. Dashed line 194 represents the division between the half of SLC Storage 122 controlled by Address ASIC-A 102 and the half controlled by Address ASIC-B 108. Each of the Tags 172, 174, 176, 178, 182, 184, 186 and 188 have respectively associated age-bits, valid-bits, and written-bits that are used for implementing a least-recently-used cache replacement algorithm. The least-recently-used cache replacement that occurs for each of the Tags is independent of the other Tags. In Storage Controller 14, O-SLC Tag 182 indicates which addresses are present and valid in half of the O-SLC Data 196 portion of SLC Storage 124, and O-SLC Tag 186 indicates which addresses are present and valid in the other half of the O-SLC Data 196. I-SLC Tag 184 and ISLC Tag 188 are used similarly for the I-SLC Data 198 portion of SLC Storage 124. Dashed line 200 represents the division between the half of SLC Storage 124 controlled by Address ASIC-A 104 and the half controlled by Address ASIC-B 110. FIG. 3 is a block diagram that shows the addressing between Address ASIC-A and Address ASIC-B and the associated Second-level Cache Storage. The Storage Controller 202 of FIG. 3 depicts one of the Storage Controllers 12 or 14 of FIG. 2. Address ASIC-A 204 represents the respective Address ASIC-A 102 or 104 within the Storage Controller, and Address ASIC-B 206 represents the respective Address ASIC-B 108 or 110 within the Storage Controller. SLC Storage 208 represents the respective SLC Storage 122 or 124 within the Storage Controller. Address inputs to each of Address ASIC-A 204 and Address ASIC-B 206 include address requests from each of the local IPs, designated as IPa, IPb, IPc, and IPd and shown respectively as Lines 210, 212. 214, and 216. Address requests from an I/O Subsystem (Subsystem 1 or Subsystem 2) are shown as input on Line 218. Address requests to Address ASIC-A 204 and Address ASIC-B 206 from the corresponding remote Address ASICs are respectively shown as Lines 220 and 222. SLC Storage 208 is comprised of four independently controlled segments referred to as Segment 0, Segment 1, Segment 2, and Segment 3. Address ASIC-A 204 controls access to Segment 0 and Segment 2, and Address ASIC-B 206 controls access to Segment 1 and Segment 3. Correspondingly, Address ASIC-A has a Segment 0 Instruction Tag 232, a Segment 0 Operand Tag 234, a Segment 2 Instruction Tag 236, and a Segment 2 Operand Tag 238. Address ASIC-B has a Segment 1 Instruction Tag 242, a Segment 1 Operand Tag 244, a Segment 3 Instruction Tag 246, and a Segment 3 Operand Tag 248. Each of the respective Tags 232, 234, 236, 238, 242, 244, 246, and 248 indicate the addresses that are present and valid in the Segments O-3. Generally, each of Segment 0, Segment 1, Segment 2, and Segment 3 maps to 1/4 of the system Memory 48. Each word of Memory that is cached in one of the segments of the SLC Storage 208 is stored across four separate devices. The four SLC Data Slices 252, 254, 256, and 258 represent the respective devices for storing 1/4 of a word. SLC Data Slice 252 stores the first quarter of a word, SLC Data Slice 254 stores the second quarter of a word, SLC Data Slice 256 stores the third quarter of a word, and SLC Data Slice 258 stores the fourth quarter of a word. Address ASIC-A 204 is coupled to each of the SLC Data Slices 252, 254, 256, and 258 via two sets of address lines 260 and 262, one for Segment 0 addresses and one for Segment 2 addresses. Similarly, Address ASIC-B 206 is coupled to each of the SLC Data Slices via two sets of address lines 264 and 266, one for Segment 1 addresses and one for Segment 3 addresses. It will be recognized that reading a word of data from SLC Storage 208 entails reading 1/4 of the word from each of the SLC Data Slices. Each of the SLC Data Slices 252, 254, 256, and 258 has respectively dedicated data write lines for writing data to SLC Storage 208, and respectively dedicated data read lines for reading data from SLC Storage. There are dedicated lines read and write lines for each of the processors and requesters that references the SLC Storage. Specifically, each of IPa, IPb, IPc, IPd, remote Address ASIC-A, remote Address ASIC-B, and the Memory 48 has dedicated read and write data lines. The write data lines to SLC Data Slice 252 are collectively referenced as 268, and the read data lines from SLC Data Slice 252 are collectively referenced as 270. Similarly, SLC Data Slices 254, 256, and 258 have respective write and read data lines that are collectively referenced as 272, 274, 276, 278, 280, and 282. FIG. 4 is a block diagram of the components that comprise a Second-level Cache Data Slice. The SLC Data Slice 283 is illustrative of each of SLC Data Slices 252, 254, 256, and 258 of FIG. 3. The SLC Data Slice includes a Data ASIC 284 and four Instruction SLC Data RAMs 285, 286, 287, and 288, one for each of Segments 0, 1, 2, and 3. The Data ASIC includes control and Operand SLC Data RAMs 289, 290, 291, and 292, again, one for each of Segments 0, 1, 2, and 3. The Data ASIC 284 controls the flow of data in to and out of the SLC Data Slice 283, both for the I-SLC Data RAMs 285, 286, 287, and 288, and for the O-SLC Data RAMs 289, 290, 291, and 292. The set of write data lines that are collectively referenced as 293 are illustrative of each of the write data lines in FIG. 3 that are referenced as 268, 272, 276, and 280. Similarly, the read data lines that are collectively referenced as 294 are illustrative of each of the read data lines of FIG. 3 that are referenced as 270, 274, 278, and 282. The address lines 260, 262, 264, and 266 are input to the Data ASIC 284. A Segment 0 set address on Line 260 is routed to the Segment 0 O-SLC Data RAM 289, a Segment 1 set address on Line 264 is routed to Segment 1 O-SLC Data RAM 290, a Segment 2 set address on Line 262 is routed to Segment 2 O-SLC Data RAM 291, and a Segment 3 set address on Line 266 is routed to Segment 3 O-SLC Data RAM 292. The set addresses are also routed to the respective I-SLC Data RAMs 285, 286, 287, and 288 as shown by set address Lines 293, 294, 295, and 296. To address a particular block within a set in a I-SLC Data RAM, block bits are encoded by the respective Address ASIC 204 or 206 based on the results of searching the respective Instruction Tags 232, 236, 242, or 246. The block bits routed to the I-SLC Data RAMs are respectively shown by Lines 297, 298, 299, and 300. The timing of the arrival of the block bits at the I-SLC Data RAM coincides with the arrival of the set address from the Data ASIC 284. The Data ASIC 284 controls reading data from and writing data to the I-SLC Data RAMs 285, 286, 287, and 288 as is respectively shown by data Lines 301, 302, 303, and 304. The interface between the Data ASIC and an I-SLC Dam RAM operates using one set of data lines for both read and write data. As a result, the interface operates using bi-directional bus techniques, whereby dead cycles are inserted when changing the bus direction. However, because the I-SLC Data RAMs are SRAM devices, they are available in very large capacities, and when used in a cache design, result in a cache having very high hit rates. The high hit rates greatly reduce the need to change the direction of the bus for reading and writing to the I-SLC Data RAM. Therefore, the disadvantage of the bi-directional interface for the I-SLC Data RAM has been overcome by storage capacity of the device. FIG. 5 is a more detailed block diagram of an Address ASIC, a Data ASIC, and a segment of Second-level Cache Storage. The Address ASIC 352 corresponds to one of Address ASIC-A 204 or Address ASIC-B 206 of FIG. 3. The Instruction-SLC Data RAM 356 corresponds to a respective one of the Instruction-SLC Data RAMs 285, 286, 287, or 288 of FIG. 4. The O-SLC Data RAM 357 corresponds to one of the O-SLC Data RAMs 289, 290, 291, or 292 of FIG. 4. For each segment controlled by the Address ASIC 352 there are two second-level cache tag structures. I-SLC Tag RAM 358 is the second-level cache instruction tag for one of the segments, and O-SLC Tag RAM 360 is the second-level cache operand tag for the corresponding one of the segments. Note that the tags for the other segment controlled by the Address ASIC 352 are not shown. The address on Line 362 is one of input addresses supplied to the Address ASIC 352 (e.g., 210, 212, 214, 216, 218, or 220). The address on Line 362 drives each of I-SLC Tag RAM 358 and O-SLC RAM 360. Each of the Tag RAMs 358 and 360 are embedded in the Address ASIC 352. At each Tag RAM, the address is split into a set address and a block address. The set address at each of the Tag RAMs may be of different widths to accommodate the different sizes of caches in the I-SLC Data RAM 356 and O-SLC Data RAM 357. The pair of set addresses are used to access both the I-SLC Tag RAM 358 and the O-SLC Tag RAM 360 simultaneously. Compare logic circuits 364 and 366 compare the block addresses read from the respective Tag RAMs 358 and 360 with the input block address. If the request is for an instruction as indicated by a function code associated with the requested address, and there is a hit in the I-SLC Tag RAM and not in the O-SLC Tag RAM, the data read out of the I-SLC Data RAMs 356 is selected via Selector 370 and routed to the requester using the read data Line 372. If the requested address is a hit in the O-SLC Tag RAM, irrespective of the results of the Compare 364, the data read from the O-SLC Data RAM is selected by Selector 370. If the function code indicates an operand read, the results of the Compare 364 are ignored and if there is a hit in the O-SLC Tag RAM, the data read from the O-SLC Data RAM is selected by Selector 370 and routed back to the requester. If an operand is to be written and there is a hit in the I-SLC Tag RAM, the I-SLC block is invalidated and the data is written into the O-SLC Data RAM. All writes occur in the O-SLC Data RAM. If an instruction read results in a miss in both the I-SLC Tag RAM 258 and the O-SLC Tag RAM 360, then a block is read from memory, written into the I-SLC Data RAM 356, and routed back to the requester. Memory Data Line 374 carries the data read from memory and being routed back to the requester via Line 372. Selector 376 selects data on Line 374 when blocks are being replaced. Write data on Line 378 is selected when an operand is being written in the O-SLC Data RAM 357. If an operand read or write operation results in a miss in both SLC Tags 358 and 360, the block is read from memory, replaced in the O-SLC Data RAM, and routed to the requester (if the function was to read an operand). For operand write misses, the block that is read from memory is merged with the new updated data from the requester and written into the O-SLC Data RAM 357. The SLC Tag RAMs 358 and 360 are respectively updated to indicate new information that is stored in the O-SLC Data RAM 357 and I-SLC Data RAMs 356. In terms of aging old information in the SLC Data RAMs 357 and 356, the data from the I-SLC Data RAM 356 does not need to be written back to memory because no write operations ever occur in the I-SLC Data RAMs. The O-SLC Data RAM 357 can be written to and therefore must be written to memory if it has been modified. There is a bit in the O-SLC Tag RAM for each referenced block that designates whether the block was modified. The I-SLC Data RAMs 356 consist of discreet SRAM components, while the O-SLC Data RAM 357 is implemented using ASIC embedded RAM structures. The cache replacement policy in the exemplary embodiment, and therefore what data is present in the I-SLC Data RAMs 356 versus the O-SLC Data RAM 357, is based on the function code information that is passed from the requesting processor to the Storage Controller 202. The function code indicates whether the request came from an instruction first-level cache or an operand first-level cache. If the request came from the instruction first-level cache, then the data is replaced in the I-SLC Data RAM 356 on a cache miss. On the other hand, if the request came from an operand first-level cache, the data is replaced into the O-SLC Data RAM 357. Because there is a separate I-SLC Tag RAM 358 and O-SLC Tag RAM 360, the aging algorithms are separate and independent. Error code correction is not required for data read from the I-SLC Data RAMs 356 because there is always an up-to-date copy of the instruction in the memory. This saves time in the access path for instruction references to the second-level cache. Additionally, the data Bus 382 is conditioned in the read direction. This minimizes the time penalty associated with reversing the direction of the data Bus. The data Bus is only required to be reversed when the cache replacement to the I-SLC Data RAM occurs. Drive control Circuits 384 and 386 control the direction of the data Bus 382, and Registers 388 and 390 respectively latch data to be written to and data read from the I-SLC Data RAMs. The operand second-level caches requires error code correction because it is operated as a post-store cache, and therefore, may have the most up-to-date data relative to the data in the memory. However, the time required for error code correction is compensated for by embedding the O-SLC Data RAM in the Data ASIC 354 and reducing off-chip crossings. The input address that drives the I-SLC Data RAMs 356 arrives from two sources. The set address is routed via Line 391 from the Data ASIC 284, and the block bits are routed to the I-SLC Data RAMs via Line 392 from the Address ASIC 352. The block bits provided on Line 392 are encoded by the Block Encode logic 393 according to the results of the Compare logic 364. If the address reference was a hit in the I-SLC Tag RAM, the particular block within the set which contains the requested address is identified by the block bits provided by Block Encode 393. FIG. 6 is a block diagram that illustrates the data path between the requesting processors, the second-level cache, and the memory. Segments 0-3 of the operand second-level cache and Segments 0-3 of the instruction second-level cache are shared between the I/O Subsystem, IPa, IPb, IPc, IPd, and the remote Address ASIC. There is also an access path to and from the Memory Subsystem (1 or 2). The data to and from these requesters is structured as separate read and write interfaces. Data is transferred to the Segments of the second-level cache from the requesters in either four or eight word packets. Data is always transferred to a requester from the second-level cache in eight word packets. Therefore it takes multiple clock cycles to transfer the information to or from the requesters. There is a four word data path to and from the O-SLC Segments 0-3 for each requester. The wide data path is cost effective because the data path is implemented using the dense routing capabilities of an ASIC and requires fewer cache cycles to handle each packet. There is only a two word interface from each of the IPs and remote requesters because the I-SLC Data RAM 356 is implemented with discreet SRAMs, and the ASICs have limited I/O capability. To handle the different sizes of interfaces, speed matching buffers were used at each requester interface. Specifically, Input Buffers 402, 404, 406, and 408 respectively handle input data from each of the local IPs, and Output Buffers 410, 412, 414, and 416 respectively handle output data to the local IPs. Input Buffers 418 and 420 respectively handle input data from the remote Segments 0 and 2 and Segments 1 and 3, and Output Buffers 422 and 424 respectively handle output data to the remote Segments 0 and 2 and Segments 1 and 3. Input Buffer 426 handles input data from the local I/O Subsystem, and Output Buffer 428 handles output data to the local I/O Subsystem. Finally, Input Buffer 430 handles input data from the local Memory Subsystem, and Output Buffer 432 handles output data to the local Memory Subsystem. FIG. 7 is a more detailed diagram of one of the O-SLC segments shown in FIG. 6. The operand second-level cache is a set associative caches with four blocks per set. The blocks are designated as Blocks 0-4. Single bit error correction and double bit error detection are provided with the ECC Generation logic circuit 422 and ECC Correction logic circuit 444. Corrected data is latched in the Correction Register 446. Feedback Path 448 is provided for read/update write operations. For read functions, both the O-SLC Tag RAM 360 and O-SLC Data RAM 357 are read together for each Block 0-3 using the set address information from the selected requester. The Hit Bits 449 from Compare logic circuit 366 are routed to Selector 370 of the Data ASIC 354 to select which block of data is to be routed to the respective Output Buffer 410, 412, 414, 416, 422, 424, 428, or 432. Selector 450 selects from the respective Input Buffers 402, 404, 406, 408, 418, 420, 426, or 430 data to be written to the O-SLC Data RAM 357 according to the selected request. Selector 452 selects between data on the feedback Path 448 and data from the Selector 450. The feedback Path 448 is used for read-modify-write operations such as for writing part of a word and for writing part of a cache block. Raw data that is read from the O-SLC Data RAM 357 is latched in the Raw Data Register 454. FIG. 8 is a more detailed diagram of the I-SLC segments shown in FIG. 6. The instruction second-level cache is implemented as a set associative cache with four blocks per set. However, unlike the operand second-level cache, the four blocks in each set of the instruction second-level cache are implemented within the I-SLC Data RAMs 356 and not with parallel block structures. This results in the look-up in the I-SLC Tag RAM 358 occurring before the reading of the I-SLC Data RAMs. The results of the Compare circuit 364 along with the input set address are used to address the I-SLC Data RAMs. The data interface to the I-SLC Data RAM 356 is bi-directional as shown by Line 382. This requires a tri-state output buffer control for both the Data ASIC 354 and the I-SLC Data RAM 356. After initialization the Output Buffer 462 is disabled by Output Drive Control logic circuit 464, and the Input Buffer 466 is enabled. Therefore, for the majority of the time, when the instruction second-level cache is performing read functions, there is no time penalty for reversing the direction of the Bus 382 because the Bus is already in the read direction. Only after a miss when a new block needs to be written into the I-SLC Data RAM 356, is the Input Buffer 466 disabled and the Output Buffer 462 enabled. After the line is written, the Output Drive Control 464 in the Data ASIC 354 and the corresponding drive control (not shown) in the I-SLC Data RAM reverse state, thereby returning to the preconditioned state. Instruction data to be written in the I-SLC Data RAM 356 is selected by Selector 468 from either the local Memory Subsystem as provided in the Input Buffers 430 or from the remote Segments as provided in a respective one of the Input Buffers 418 or 420. The selection is made based upon the request in process. FIG. 9 is a block diagram of the overall address path of the exemplary system. There is a single address interface from each of the local IPs, the local I/O Subsystem, and the remote Address ASIC (e.g., 102, 104, 108, or 110) as shown respectively by address Lines 502, 504, 506, 508, 510, and 512. The address interface branches off into respective Read Address Registers 514, 516, 518, 520, 522, and 524, and into respective Write Address Registers 526, 528, 530, 532, 534, and 536. This means that each requester can have a single read and a single write request outstanding to the second-level cache before being acknowledged. Generally, the acknowledgment comes when the second-level cache has completed as request, thereby letting the requester know that it can send another request. There are separate acknowledgments for read and write requests. After a request and its address are latched, the request and address are routed to one of the Segment Queues 542, 544, 546, or 548. There is a dedicated Segment Queue for each Segment 0-3 of the second-level cache. The Segment Queue to which the request is routed depends upon the requested address. Each of the Segments 0-3 operates independently and in parallel. That is, Segment 11 can be working on one request while Segment 1 is working on another request. Each of the Segments then selects an input request or a feedback request based upon the predetermined queuing priority and route the address to both the corresponding O-SLC Tag and the I-SLC Tag. FIG. 10 is a detailed block diagram of an O-SLC Tag logic circuit. The Segment Queue Address that is input on Line 602 is from a respective one of the Segment Queues 542, 544, 546 or 548. The set address field is routed to both the O-SLC Tag RAM 360 and to the O-SLC Data RAM 357. Set Address Register 604 latches the set address for the Data RAM. The second-level cache tag is divided into four parallel structures referenced as Block 0, Block 1, Block 2, and Block 3. Each Block consists of an embedded O-SLC Tag RAM 360, error correction logic, and compare logic. The Segment Queue Address 602 is divided into a set address provided on Line 606 and a block address that is provided on Line 608. The set address is used to address the O-SLC Tag RAMs 360, and the block address is used to compare against the information stored in the O-SLC Tag RAMs. If the block address matches data read from the O-SLC Tag RAMs, then the data requested is located in the O-SLC Data RAM 357 and can be accessed there rather than in either the local or remote Memory Subsystems. The O-SLC Tag RAMs 360 and the O-SLC Data RAM 357 are read in parallel, and the selection of the block is based on the results of the respective Compare logic circuits 610 that are stored in the respective Hit Registers 612. The respective outputs from the Hit Registers 612 are encoded by Encode logic 614 into Hit Bits 449 to select one of the blocks read from the O-SLC Data RAM if a hit occurs. Single bit error correction and double bit error detection are provided with the ECC Generation logic circuit 616 and ECC Correction logic circuit 618. Feedback Path 620 is provided for read/update write operations. Selector 622 selects between data resulting from read/update write operations and a Block Address 608. Write Register 624 latches a block address for writing it to the O-SLC Tag RAM 360, and Staging Register 626 stages the input Block Address 608 for comparing the input Block Address with data read from the O-SLC Tag RAM. FIG. 11 is a detailed block diagram of an I-SLC Tag logic circuit. The structure is essentially similar to the O-SLC Tag logic circuit of FIG. 10, except that them is no need for ECC correction. Parity detection, which is much faster and simpler, is used instead of ECC correction. If there is a parity error in an instruction mad from the second-level cache, the instruction may be read instead from the Memory 48. The Segment Queue Address that is input on Line 632 is from a respective one of the Segment Queues 542, 544, 546 or 548. The set address field is routed to both the I-SLC Tag RAM 358 and to the I-SLC Data RAMs 356. The second-level cache tag is divided into four parallel structures referenced as Block 0, Block 1, Block 2, and Block 3. Each Block consists of an embedded I-SLC Tag RAM 358 and compare logic. The Segment Queue Address 632 is divided into a set address provided on Line 634 and a block address that is provided on Line 636. The set address is used to address the respective I-SLC Tag RAMs 358, and the block address is used to compare against the information stored in the respective I-SLC Tag RAMs. If the block address matches data read from the I-SLC Tag RAMs, then the instruction requested is present in the second-level cache (one of the respective ISLC Data RAMs 356 and can be accessed there rather than in either the local or remote Memory Subsystems. Three registers are used to stage the set address 634 before forwarding it to the I-SLC Data RAM 356. The three staging registers are designated as Stage-0 Set Address Register 638, Stage-1 Set Address Register 640, and Stage-2 Set Address Register 642. The staging of the set address ensures that the timing of the arrival of the encoded hit Lines 644 matches that of the set address on Line 646. This is required because the blocks of the I-SLC Data RAMs are not separate RAM structures as for the O-SLC Data RAMs 357. The selection of the block is based on the results of the respective Compare logic circuits 648 that are stored in the respective Hit Registers 650. The respective outputs from the Hit Registers are encoded by Block Encode logic 393 into Hit Bits 644 to select a block to be read from the respective I-SLC Data RAM if a hit occurs. Parity errors are detected by Parity Check logic circuit 654. Feedback Path 656 is provided for read/update write operations. Selector 658 selects between a new address made available on Line 632, which is used to search the I-SLC Tag RAM 358, and the new replacement address on Line 656, which is used to write into the I-SLC Tag RAM after a cache miss. Write Register 660 latches a block address that is the new replacement address for writing into the respective I-SLC Tag RAM 358. Staging Register 662 stages the input Block Address 636 for comparing the input Block Address with data read from the I-SLC Tag RAM. In the exemplary system, the instruction second-level cache and operand second-level cache tag cycles operate in tandem. This simplifies maintaining cache coherency between the instruction and operand second-level caches. In addition, there is sufficient tag bandpass available to meet the request rate of all the requesters, with no significant performance loss relative to any speed advantage that might be obtained by operating the instruction and operation second-level cache tags as independent elements. However, it should be noted that the data portions of the instruction and operand second-level caches do not necessarily operate in tandem. This is because for a read, since the operand second-level cache is twice as wide as the instruction second-level cache, twice as many clock cycles are required by the instruction second-level cache to read a block. Therefore, a blocking scheme is used. The block scheme ensures that while the instruction second-level cache is reading data, future instruction second-level cache requests are blocked in the segment priority until the instruction second-level cache data read is complete. However, operand requests are allowed to flow into both the operand and instruction second-level cache tags when it is complete with its previous search. Having described an exemplary embodiment of the invention in the drawings and accompanying description, those skilled in the art will recognize that various modifications to the exemplary embodiment could be made without departing from the scope and spirit of the claims set forth below:
A multiprocessor data processing system having store-through first-level caches with separate instruction and operand sections and a store-in second-level cache that is shared between the processors and which has separate instruction and operand sections. Dual second-level caches, each mappable to all of shared memory, enhance cache performance. The second-level cache memory space is divided into a plurality of segments, with each segment having a dedicated instruction tag memory, a dedicated operand tag memory, a dedicated instruction cache memory, and a dedicated operand cache memory. The segments may be addressed in parallel to further enhance cache performance.
Summarize the information, clearly outlining the challenges and proposed solutions.
[ "CROSS-REFERENCE This patent application is related to the co-pending U.S. patent application Ser.", "No. 08/579,897, entitled, A MULTI-PROCESSOR DATA PROCESSING SYSTEM WITH MULTIPLE SECOND LEVEL CACHES MAPABLE TO ALL OF ADDRESSABLE MEMORY, filed concurrent herewith by Bauman et al.", ", and which is assigned to the assignee of the present invention.", "BACKGROUND 1.", "Field of the Invention This invention generally relates to cache architectures for data processing systems and more particularly to a shared memory multi-processor data processing system having a plurality of second-level caches, where each of the second-level is comprised of a separate instruction second-level cache and a separate operand second-level cache.", "Description of the Prior Art Multilevel storage hierarchies have been used to enhance the performance of data processing systems.", "Smaller higher speed memories, often called cache memories, are located in the storage access path between an instruction processor and the system's main memory.", "Instructions and operands present in the cache memories can be referenced more quickly than instructions and operands located in the system's main memory.", "Various cache structures have been used to gain assorted advantages from cache memories.", "U.S. Pat. No. 5,386,547 to Jouppi shows a cache architecture within a single processor data processing system.", "The cache architecture of Jouppi shows what are referred to by Jouppi as first and second-level caches.", "The first and second-level caches swap data, thereby seeking to gain some level of associativity from a direct-mapped cache.", "Jouppi also shows multi-level cache architecture with separate instruction and operand caches.", "The objective sought for having separate instruction and operand caches is to separate the application of the cache replacement algorithms to each of the separate caches.", "U.S. Pat. No. 5,423,016 to Tsuchiya et al, illustrates a store-through first-level cache that is split into a separate instruction and operand section.", "The second-level cache stores both instructions and operands and is shared between multiple processors.", "Therefore, the second-level cache of Tsuchiya makes no distinction between instructions and operands, and its caching algorithms are the same for both types of references.", "SUMMARY OF THE INVENTION The present invention overcomes the shortcomings of the prior art by providing a multiprocessor data processing system that has store-through first-level caches associated with each of the processors, each of the first-level caches having a separate instruction cache and operand cache, and a second-level cache that is shared between the processors where the second-level cache also has a separate instruction cache and operand cache.", "The Jouppi cache architecture does not provide a workable solution for a multiprocessor shared memory data processing system.", "Jouppi does not disclose how cache coherency could be maintained in a multiprocessor shared memory system.", "In addition, Jouppi has a high overhead cost associated with swapping data between the first-level and second-level cache.", "The Tsuchiya cache architecture illustrates a multi-level cache architecture for a multiprocessor data processing system.", "However, Tsuchiya has many remote interfaces required for second-level cache access, and additionally, mixes instructions and operands in the second-level cache.", "A primary objective of the present invention is to improve the cost/performance ratio for a multi-processor data processing system.", "This objective and others are achieved by effectively matching the appropriate cache algorithms and technology to the different characteristics associated with instructions and operands in a second-level cache.", "The characteristics associated with instruction references as compared to operand references, relative to a second-level cache that supports store-through first-level caches, are very different.", "First, instruction references are always read operations to the second-level cache.", "Instruction references also conform closely to the principle of locality of reference.", "Instructions are rarely modified by the instruction reference generator, and therefore have a backup copy in memory.", "As a result, the second-level cache does not need to provide additional error correction logic for instructions.", "Eliminating error correction logic for instructions reduces access time.", "Operand references can be both read and write operations.", "Relative to the second-level cache, a significant majority of the operations are write operations where there are store-through first-level caches.", "Operand references to the second-level cache do not benefit as well as do instructions from having a large cache.", "This is because operands do not follow the locality of reference principle as well as instructions.", "The main benefit that the second-level cache provides for operands is the ability to quickly handle the write operations that flow through the first-level caches and to share the modified data with other processors in the multiprocessor environment.", "Because most second-level caches operate in a strife-in mode, the second-level cache has the most recent updated copy of the operand and there is no backup copy available in the system memory.", "Therefore, error correction is required to ensure reliable operation.", "Historically, cache RAM structures have been implemented in two ways: one is using discrete SRAM devices that are somewhat limited in functionality and very limited in interconnect options, but have good density and cost factors;", "and the second way is using embedded RAM structures within ASICs.", "The embedded RAM structures have very good functionality characteristics and minimal interconnect constraints, but have very high cost factors for a given density.", "A major advantage of SRAM devices is that they are available in very large capacities, and as a result, when used in a cache design, they provide for having a very high cache hit rate.", "However, in order to minimize package size and maximize density, many SRAMs that are used in cache systems have one set of data lines for both read and write data.", "As a result, they operate using bi-directional bus techniques, whereby dead cycles are inserted when changing bus direction (e.g., changing from a read direction to a write direction).", "The dead cycles slow down system performance.", "In contrast, the embedded RAMs within an ASIC have very good interconnection options because of their inherent dense routing capability within the ASIC.", "Therefore, the embedded RAMs have separate data read and write lines and no dead cycles are required to change bus direction as in the SRAM devices.", "In addition, embedded RAMs usually have faster access times because they are physically closer to the logic that they interface with.", "The embedded RAMs have a cost disadvantage as compared with the SRAM devices because they are unique designs with limited volume for each application.", "The result of the above is that the characteristics associated with instructions map very well to SRAM devices.", "The bus can be preconditioned to the read direction and rarely needs to be changed to the write direction.", "Therefore, dead cycles associated with changing bus direction are greatly reduced.", "The slower access time associated with the SRAM devices is compensated for by not having to take time to do error correction.", "In addition, the larger cache size afforded by the SRAMs is more predominant for instructions.", "The objectives of the present invention are achieved in a multiprocessor data processing system.", "The system includes a plurality of processors, each having a respective first-level cache.", "A second-level cache is between the first-level caches and the system memory in the storage hierarchy.", "The first-level caches are store-through type caches, and are separated into an instruction cache and an operand cache.", "The second-level cache is a store-in cache that is shared between the processors.", "The second-level cache is also divided into a separate instruction cache and operand cache.", "Cache replacement is independent between the instruction second-level cache and the operand second-level cache.", "In another aspect of the invention, if an instruction read is issued to the second-level cache, it is routed to both the operand second-level cache and to the instruction second-level cache.", "If an instruction read results in a hit in the operand second-level cache, the block from the operand second-level cache is returned to the requesting processor.", "This provides data integrity in the case where instructions and operands are intermixed within a block of cached data.", "A further aspect of the invention has the second-level cache divided into a plurality of segments.", "Each of the segments is dedicated to caching a predetermined portion of addressable memory.", "Each of the segments further has an associated, respective operand tag memory and an associated, respective instruction tag memory.", "Further still, each of the segments has an associated, respective operand memory and an associated, respective instruction memory.", "Dual second-level cache memories, each having an separate operand cache and instruction cache, define a further aspect of the invention.", "Each of the second-level cache memories is mappable to all of the system memory.", "The aforementioned aspects of the invention are also utilized in combination with the dual second-level cache memories.", "Still other objects and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein only the preferred embodiment of the invention is shown, simply by way of illustration of the best mode contemplated for carrying out the invention.", "As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various respects, all without departing from the invention.", "Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a multi-processor data processing system in which the present invention is embodied;", "FIG. 2 is a more detailed block diagram of the storage controls and interconnections between the components of the Storage Controllers;", "FIG. 3 is a block diagram of the addressing between Address ASIC-A and Address ASIC-B and the associated Second-level Cache Storage;", "FIG. 4 is a block diagram of the components that comprise a Second-level Cache Data Slice;", "FIG. 5 is a more detailed block diagram of an Address ASIC, a Data ASIC, and a segment of Second-level Cache Storage: FIG. 6 is a block diagram that illustrates the data path between the requesting processors, the second-level cache, and the memory;", "FIG. 7 is a more derailed diagram of one of the O-SLC segments shown in FIG. 6;", "FIG. 8 is a more detailed diagram of the I-SLC segments shown in FIG. 5;", "FIG. 9 is a block diagram of the overall address path of the exemplary system;", "FIG. 10 is a detailed block diagram of an O-SLC Tag logic circuit;", "and FIG. 11 is a derailed block diagram of an I-SLC Tag logic circuit.", "DETAILED DESCRIPTION FIG. 1 is a block diagram of a multi-processor data processing system in which the present invention is embodied.", "The system includes eight Instruction Processors, IP1, IP2, IP3, IP4, IP5, IP6, IP7, and IP8, each having a dedicated store-through first-level cache.", "The first-level cache in each of the IPs includes a dedicated instruction cache and a separate dedicated operand cache.", "Both of the first-level caches are 8K words in size and are organized as 256 sets of four blocks, each block containing 8 words.", "The operand first-level cache operates as a store-through cache.", "This means that all write operands are stored into the operand first-level cache if the address is resident there and also passed on to the second-level cache.", "If the requested write operand is not resident in the operand first-level cache, the operand is not made resident in the operand first-level cache.", "Blocks of instructions and operands are made resident in the first-level caches on read-misses only.", "The system of FIG. 1 has two Storage Controllers 12 and 14.", "Each of Storage Controllers is coupled to four of the IPs.", "Lines 22, 24, 26, and 28 illustrate the respective point-to-point couplings between the IP1, IP2, IP3, IP4 and Storage Controller 12.", "Lines 22, 24, 26, and 28 represent the collection of control, data, and address lines between the IPs and the Storage Controller.", "Lines 32, 34, 36, and 38 represent similar couplings between Storage Controller 14 and IP5, IP6, IP7, and IP8 respectively.", "Memory requests can also come from components within the I/O Subsystem 1 and I/O Subsystem 2.", "I/O Subsystem I is coupled to Storage Controller 12 via Line 40, and I/O Subsystem 2 is coupled to Storage Controller 14 via Line 41.", "Each of the Storage Controllers 12 and 14 has a respective Global SLC 42 and 44.", "The Global SLCs are described as "global"", "because each is mapable to the all of system's addressable memory.", "That is, the entire address range of the addressable memory is cacheable by each of the Global SLCs.", "The total available addressable memory is designated by Shared Main Memory 48.", "The Shared Main Memory is comprised of two Memory Subsystems, Memory Subsystem I and Memory Subsystem 2.", "Global SLC 42 is coupled to Global SLC 44 in a point-to-point fashion as illustrated by Line 52.", "Line 52 is comprised of data, address, and control lines.", "Global SLC 42 may be accessed directly by IP1, IP2, IP3, and IP4, and indirectly accessed by IP5, IP6, IP7, and IP8.", "Similarly, Global SLC 44 may be accessed directly by IP5, IP6, IP7, and IP8, and indirectly by IP1, IP2, IP3, and IP4.", "If IP1 issues a read request for an address of Memory Subsystem 2 which is neither in IP1's FLC nor in Global SLC 42, the request is forwarded to Global SLC 44.", "If the requested address is present in Global SLC 44, the data of the requested address is returned to Global SLC 42.", "If the requested address is a miss in Global SLC 44, the request is forwarded to Memory Subsystem 2.", "The data is then returned to Global SLC 42.", "Note that no replacement of data takes place in Global SLC 44 as a result of requests from Global SLC 42.", "Storage Controller 12 and Global SLC 42 are "local"", "relative to IP1, IP2, IP3, IP4, and I/O Subsystem 1, and are "remote"", "relative to IP5, IP6, IP7, IP8, and I/O Subsystem 2.", "Similarly Storage controller 14 and Global SLC 44 are "local"", "relative to IP5, IP6, IP7, IP8, and I/O Subsystem 2, and are "remote"", "relative to IP1, 1P2, IP3, IP4, and I/O Subsystem 1.", "The Global SLCs may be viewed as dedicated to the requests of their respective local IPs and cooperating in servicing requests from the remote IPs.", "Global SLC 42 is dedicated to IP1, IP2, IP3, and IP4 in that the SLC storage is dedicated to caching data based on requests from IP1, IP2, IP3, and IP4.", "Similarly, Global SLC 44 is dedicated to IP5, IP6, IP7, and IP8 in that the SLC storage is dedicated to caching data based on requests from IP5, IP6, IP7, and IP8.", "Each of the Global SLCs 42 and 44 has a respective, dedicated Instruction SLC (I-SLC) and a dedicated Operand SLC (O-SLC).", "Global SLC 42 includes I-SLC 62, and O-SLC 64, and Global SLC 44 includes I-SLC 66 and O-SLC 68.", "Each of the I-SLCs is implemented using high speed external SRAMs. The O-SLCs, on the other hand, are implemented using embedded SRAMs. There are several advantages to separating the instructions from the operands in the SLC.", "One advantage is that performance is increased.", "Namely, the storing or reading of operands will not cause an aging of the instructions within the same set address.", "Operand and instruction contention has therefore been eliminated.", "A second advantage is that there is speed matching between instructions and operands in the SLC because of different respective requirements.", "This minimizes SLC latency.", "The I-SLC, using the external SRAMs has a longer access time.", "However, error correction is not required for reading instructions from the I-SLC, thereby saving time.", "Error correction is not required because the instructions in the I-SLC are only copies of that which is maintained in the Main Memory 48.", "If an error is detected, the copy from the Memory can be re-fetched to correct the error.", "While the O-SLC does require error correction because it may have the only copy in the system, its access time is shortened because the O-SLC storage is an embedded SRAM.", "Cache coherency is accomplished with two primary mechanisms.", "The store-through FLCs use an invalidate mechanism, and the Global SLCs 42 and 44 use a combination of invalidate and tracking which Global SLC was the last to modify cached data ("last-modified").", "The FLC invalidate mechanism has two major components: a valid file located in the respective IPs, and the respective Duplicated Tags that are located in the respective Storage Controllers 12 and 14.", "Note that Duplicate Tags for IP1, IP2, IP3, and IP4 are designated as block 72 in Storage Controller 12 and Duplicate Tags for IP5, IP6, IP7, and IP8 are designated as block 74 in Storage Controller 14.", "The Duplicated Tags are essentially a copy of the respective FLC tags (not shown).", "The respective Duplicate Tag is updated when an IP updates its FLC tag, namely, on a read-miss of the FLC.", "When any local IP performs a write operation, the IP will write to its respective O-FLC if the address is resident and then pass the write operation to the local Storage Controller.", "The local Storage Controller then searches the local Duplicate Tags.", "If there is a match, the appropriate IP is notified as to which set and which block needs to be invalidated in its FLC tag.", "The IP then clears out the associated valid bit in its valid file.", "This forces the next read by that IP to result in a miss in its FLC and the updated information being fetched from the local Global SLC.", "If the write address is not present in the FLC, the same invalidation scenario occurs, however, no replacement occurs in the FLC.", "A technique referred to as last-modified is used by the Global SLCs 42 and 44 to coordinate cache coherency.", "In order for a Global SLC to allow a write to occur in its storage, it must first be designated as being the Global SLC that last-modified the specified address.", "Only one Global SLC is allowed to be designated as being the last to modify a particular address.", "If a Global SLC is already designated as having last-modified an address when a write operation for the address is received, the write operation is processed immediately.", "If the Global SLC is not designated as having last-modified the address when the write operation is received, then the remote Global SLC is checked to see whether the remote Global SLC has a copy of the data.", "As the remote Global SLC is checking for a copy, it is also invalidating the remote Duplicate Tags and the remote FLC tags.", "If the remote Global SLC has a copy of the data, the data is returned to the local SLC and the remote Global SLC invalidates its tags.", "Therefore, all remote caches have been purged of the requested block.", "The local Global SLC is then designated as having last-modified the block, and any subsequent write operations from the local processors do not require invalidation to be performed at the remote caches.", "This method works especially well with instructions because there can be copies in both of the Global SLCs.", "If both Global SLCs have copies of the block, there is no remote access penalty for an FLC miss.", "FIG. 2 is a more detailed block diagram of the storage controls and interconnections between the components of the Storage Controllers 12 and 14.", "Each of the Storage Controllers has two Address ASICs, Address ASIC-A and Address ASIC-B.", "Address ASIC-A 102 of Storage Controller 12 is directly coupled to Address ASIC-A 104 of Storage Controller 14 via Line 106.", "Similarly Address ASIC-B 108 is directly coupled to Address ASIC-B 110 via Line 112.", "Lines 106 and 108 are comprised of unidirectional data, address, and control lines.", "For the respective Global SLCs 42 and 44, each of the Address ASICs 102, 104, 106, and 108 contain a Tag for 1/2 of the addressable memory space provided by system Memory 48.", "Specifically, Address ASIC-A 102 contains control and a tag for managing 1/2 of the system's addressable memory for caching in SLC Storage 122, and Address ASIC-B 108 contains control and a tag for managing the other half of the system's addressable memory for caching in SLC Storage 122.", "Address ASIC-A 104 and Address ASIC-B 110 perform similar functions with respect to SLC Storage 124.", "Address ASIC-A 102 and Address ASIC-B 108 are directly coupled to IP1, IP2, IP3, IP4, and I/O Subsystem 1 as is respectively shown by Lines 132, 134, 136, 138, and 140.", "Lines 132, 134, 136, 138 and 140 include unidirectional address, data, and control lines.", "Address ASIC-A 102 includes Duplicate Tags (not shown) for IP1's FLC and for IP2's FLC, and Address ASIC-B 108 includes Duplicate Tags (not shown) for IP3's FLC and for IP4's FLC.", "IP5, IP6, IP7, IP8, and I/O Subsystem 2 are directly coupled to Address ASIC-A 104 and Address ASIC-B 110 in a similar manner as shown by Lines 142, 144, 146, 148, and 151).", "Address ASIC-A 104 contains Duplicate Tags (not shown) for IP5's FLC and for IP6's FLC, and Address ASIC-B 110 contains Duplicate Tags (not shown) for IP7's FLC and for IP8's FLC.", "Address ASIC-A 102 is directly coupled to Address ASIC-B 108 via Line 162.", "Line 162 is comprised of unidirectional control lines that provide for transmission of invalidation requests to be processed against the Duplicate Tags that are respectively included in each of Address ASIC-A and Address ASIC-B.", "Line 164 is a similar coupling between Address ASIC-A 104 and Address ASIC-B 110.", "Each of the Address ASICs has a respective Operand SLC Tag and a Instruction SLC Tag.", "Specifically, Address ASIC-A 102 has O-SLC Tag 172 and I-SLC 174, Address ASIC-B 108 has O-SLC Tag 176 and I-SLC Tag 178, Address ASIC A 104 has O-SLC Tag 182 and ISLC Tag 184, and Address ASIC-B 110 has O-SLC Tag 186 and I-SLC Tag 188.", "O-SLC Tag 172 indicates which addresses are present and valid in half of the O-SLC Data 190 portion of SLC Storage 122, and O-SLC Tag 176 indicates which addresses are present and valid in the other half of the O-SLC Data 190.", "I-SLC Tag 174 and I-SLC Tag 178 are used similarly for the I-SLC Data 192 portion of SLC Storage 122.", "Dashed line 194 represents the division between the half of SLC Storage 122 controlled by Address ASIC-A 102 and the half controlled by Address ASIC-B 108.", "Each of the Tags 172, 174, 176, 178, 182, 184, 186 and 188 have respectively associated age-bits, valid-bits, and written-bits that are used for implementing a least-recently-used cache replacement algorithm.", "The least-recently-used cache replacement that occurs for each of the Tags is independent of the other Tags.", "In Storage Controller 14, O-SLC Tag 182 indicates which addresses are present and valid in half of the O-SLC Data 196 portion of SLC Storage 124, and O-SLC Tag 186 indicates which addresses are present and valid in the other half of the O-SLC Data 196.", "I-SLC Tag 184 and ISLC Tag 188 are used similarly for the I-SLC Data 198 portion of SLC Storage 124.", "Dashed line 200 represents the division between the half of SLC Storage 124 controlled by Address ASIC-A 104 and the half controlled by Address ASIC-B 110.", "FIG. 3 is a block diagram that shows the addressing between Address ASIC-A and Address ASIC-B and the associated Second-level Cache Storage.", "The Storage Controller 202 of FIG. 3 depicts one of the Storage Controllers 12 or 14 of FIG. 2. Address ASIC-A 204 represents the respective Address ASIC-A 102 or 104 within the Storage Controller, and Address ASIC-B 206 represents the respective Address ASIC-B 108 or 110 within the Storage Controller.", "SLC Storage 208 represents the respective SLC Storage 122 or 124 within the Storage Controller.", "Address inputs to each of Address ASIC-A 204 and Address ASIC-B 206 include address requests from each of the local IPs, designated as IPa, IPb, IPc, and IPd and shown respectively as Lines 210, 212.", "214, and 216.", "Address requests from an I/O Subsystem (Subsystem 1 or Subsystem 2) are shown as input on Line 218.", "Address requests to Address ASIC-A 204 and Address ASIC-B 206 from the corresponding remote Address ASICs are respectively shown as Lines 220 and 222.", "SLC Storage 208 is comprised of four independently controlled segments referred to as Segment 0, Segment 1, Segment 2, and Segment 3.", "Address ASIC-A 204 controls access to Segment 0 and Segment 2, and Address ASIC-B 206 controls access to Segment 1 and Segment 3.", "Correspondingly, Address ASIC-A has a Segment 0 Instruction Tag 232, a Segment 0 Operand Tag 234, a Segment 2 Instruction Tag 236, and a Segment 2 Operand Tag 238.", "Address ASIC-B has a Segment 1 Instruction Tag 242, a Segment 1 Operand Tag 244, a Segment 3 Instruction Tag 246, and a Segment 3 Operand Tag 248.", "Each of the respective Tags 232, 234, 236, 238, 242, 244, 246, and 248 indicate the addresses that are present and valid in the Segments O-3.", "Generally, each of Segment 0, Segment 1, Segment 2, and Segment 3 maps to 1/4 of the system Memory 48.", "Each word of Memory that is cached in one of the segments of the SLC Storage 208 is stored across four separate devices.", "The four SLC Data Slices 252, 254, 256, and 258 represent the respective devices for storing 1/4 of a word.", "SLC Data Slice 252 stores the first quarter of a word, SLC Data Slice 254 stores the second quarter of a word, SLC Data Slice 256 stores the third quarter of a word, and SLC Data Slice 258 stores the fourth quarter of a word.", "Address ASIC-A 204 is coupled to each of the SLC Data Slices 252, 254, 256, and 258 via two sets of address lines 260 and 262, one for Segment 0 addresses and one for Segment 2 addresses.", "Similarly, Address ASIC-B 206 is coupled to each of the SLC Data Slices via two sets of address lines 264 and 266, one for Segment 1 addresses and one for Segment 3 addresses.", "It will be recognized that reading a word of data from SLC Storage 208 entails reading 1/4 of the word from each of the SLC Data Slices.", "Each of the SLC Data Slices 252, 254, 256, and 258 has respectively dedicated data write lines for writing data to SLC Storage 208, and respectively dedicated data read lines for reading data from SLC Storage.", "There are dedicated lines read and write lines for each of the processors and requesters that references the SLC Storage.", "Specifically, each of IPa, IPb, IPc, IPd, remote Address ASIC-A, remote Address ASIC-B, and the Memory 48 has dedicated read and write data lines.", "The write data lines to SLC Data Slice 252 are collectively referenced as 268, and the read data lines from SLC Data Slice 252 are collectively referenced as 270.", "Similarly, SLC Data Slices 254, 256, and 258 have respective write and read data lines that are collectively referenced as 272, 274, 276, 278, 280, and 282.", "FIG. 4 is a block diagram of the components that comprise a Second-level Cache Data Slice.", "The SLC Data Slice 283 is illustrative of each of SLC Data Slices 252, 254, 256, and 258 of FIG. 3. The SLC Data Slice includes a Data ASIC 284 and four Instruction SLC Data RAMs 285, 286, 287, and 288, one for each of Segments 0, 1, 2, and 3.", "The Data ASIC includes control and Operand SLC Data RAMs 289, 290, 291, and 292, again, one for each of Segments 0, 1, 2, and 3.", "The Data ASIC 284 controls the flow of data in to and out of the SLC Data Slice 283, both for the I-SLC Data RAMs 285, 286, 287, and 288, and for the O-SLC Data RAMs 289, 290, 291, and 292.", "The set of write data lines that are collectively referenced as 293 are illustrative of each of the write data lines in FIG. 3 that are referenced as 268, 272, 276, and 280.", "Similarly, the read data lines that are collectively referenced as 294 are illustrative of each of the read data lines of FIG. 3 that are referenced as 270, 274, 278, and 282.", "The address lines 260, 262, 264, and 266 are input to the Data ASIC 284.", "A Segment 0 set address on Line 260 is routed to the Segment 0 O-SLC Data RAM 289, a Segment 1 set address on Line 264 is routed to Segment 1 O-SLC Data RAM 290, a Segment 2 set address on Line 262 is routed to Segment 2 O-SLC Data RAM 291, and a Segment 3 set address on Line 266 is routed to Segment 3 O-SLC Data RAM 292.", "The set addresses are also routed to the respective I-SLC Data RAMs 285, 286, 287, and 288 as shown by set address Lines 293, 294, 295, and 296.", "To address a particular block within a set in a I-SLC Data RAM, block bits are encoded by the respective Address ASIC 204 or 206 based on the results of searching the respective Instruction Tags 232, 236, 242, or 246.", "The block bits routed to the I-SLC Data RAMs are respectively shown by Lines 297, 298, 299, and 300.", "The timing of the arrival of the block bits at the I-SLC Data RAM coincides with the arrival of the set address from the Data ASIC 284.", "The Data ASIC 284 controls reading data from and writing data to the I-SLC Data RAMs 285, 286, 287, and 288 as is respectively shown by data Lines 301, 302, 303, and 304.", "The interface between the Data ASIC and an I-SLC Dam RAM operates using one set of data lines for both read and write data.", "As a result, the interface operates using bi-directional bus techniques, whereby dead cycles are inserted when changing the bus direction.", "However, because the I-SLC Data RAMs are SRAM devices, they are available in very large capacities, and when used in a cache design, result in a cache having very high hit rates.", "The high hit rates greatly reduce the need to change the direction of the bus for reading and writing to the I-SLC Data RAM.", "Therefore, the disadvantage of the bi-directional interface for the I-SLC Data RAM has been overcome by storage capacity of the device.", "FIG. 5 is a more detailed block diagram of an Address ASIC, a Data ASIC, and a segment of Second-level Cache Storage.", "The Address ASIC 352 corresponds to one of Address ASIC-A 204 or Address ASIC-B 206 of FIG. 3. The Instruction-SLC Data RAM 356 corresponds to a respective one of the Instruction-SLC Data RAMs 285, 286, 287, or 288 of FIG. 4. The O-SLC Data RAM 357 corresponds to one of the O-SLC Data RAMs 289, 290, 291, or 292 of FIG. 4. For each segment controlled by the Address ASIC 352 there are two second-level cache tag structures.", "I-SLC Tag RAM 358 is the second-level cache instruction tag for one of the segments, and O-SLC Tag RAM 360 is the second-level cache operand tag for the corresponding one of the segments.", "Note that the tags for the other segment controlled by the Address ASIC 352 are not shown.", "The address on Line 362 is one of input addresses supplied to the Address ASIC 352 (e.g., 210, 212, 214, 216, 218, or 220).", "The address on Line 362 drives each of I-SLC Tag RAM 358 and O-SLC RAM 360.", "Each of the Tag RAMs 358 and 360 are embedded in the Address ASIC 352.", "At each Tag RAM, the address is split into a set address and a block address.", "The set address at each of the Tag RAMs may be of different widths to accommodate the different sizes of caches in the I-SLC Data RAM 356 and O-SLC Data RAM 357.", "The pair of set addresses are used to access both the I-SLC Tag RAM 358 and the O-SLC Tag RAM 360 simultaneously.", "Compare logic circuits 364 and 366 compare the block addresses read from the respective Tag RAMs 358 and 360 with the input block address.", "If the request is for an instruction as indicated by a function code associated with the requested address, and there is a hit in the I-SLC Tag RAM and not in the O-SLC Tag RAM, the data read out of the I-SLC Data RAMs 356 is selected via Selector 370 and routed to the requester using the read data Line 372.", "If the requested address is a hit in the O-SLC Tag RAM, irrespective of the results of the Compare 364, the data read from the O-SLC Data RAM is selected by Selector 370.", "If the function code indicates an operand read, the results of the Compare 364 are ignored and if there is a hit in the O-SLC Tag RAM, the data read from the O-SLC Data RAM is selected by Selector 370 and routed back to the requester.", "If an operand is to be written and there is a hit in the I-SLC Tag RAM, the I-SLC block is invalidated and the data is written into the O-SLC Data RAM.", "All writes occur in the O-SLC Data RAM.", "If an instruction read results in a miss in both the I-SLC Tag RAM 258 and the O-SLC Tag RAM 360, then a block is read from memory, written into the I-SLC Data RAM 356, and routed back to the requester.", "Memory Data Line 374 carries the data read from memory and being routed back to the requester via Line 372.", "Selector 376 selects data on Line 374 when blocks are being replaced.", "Write data on Line 378 is selected when an operand is being written in the O-SLC Data RAM 357.", "If an operand read or write operation results in a miss in both SLC Tags 358 and 360, the block is read from memory, replaced in the O-SLC Data RAM, and routed to the requester (if the function was to read an operand).", "For operand write misses, the block that is read from memory is merged with the new updated data from the requester and written into the O-SLC Data RAM 357.", "The SLC Tag RAMs 358 and 360 are respectively updated to indicate new information that is stored in the O-SLC Data RAM 357 and I-SLC Data RAMs 356.", "In terms of aging old information in the SLC Data RAMs 357 and 356, the data from the I-SLC Data RAM 356 does not need to be written back to memory because no write operations ever occur in the I-SLC Data RAMs. The O-SLC Data RAM 357 can be written to and therefore must be written to memory if it has been modified.", "There is a bit in the O-SLC Tag RAM for each referenced block that designates whether the block was modified.", "The I-SLC Data RAMs 356 consist of discreet SRAM components, while the O-SLC Data RAM 357 is implemented using ASIC embedded RAM structures.", "The cache replacement policy in the exemplary embodiment, and therefore what data is present in the I-SLC Data RAMs 356 versus the O-SLC Data RAM 357, is based on the function code information that is passed from the requesting processor to the Storage Controller 202.", "The function code indicates whether the request came from an instruction first-level cache or an operand first-level cache.", "If the request came from the instruction first-level cache, then the data is replaced in the I-SLC Data RAM 356 on a cache miss.", "On the other hand, if the request came from an operand first-level cache, the data is replaced into the O-SLC Data RAM 357.", "Because there is a separate I-SLC Tag RAM 358 and O-SLC Tag RAM 360, the aging algorithms are separate and independent.", "Error code correction is not required for data read from the I-SLC Data RAMs 356 because there is always an up-to-date copy of the instruction in the memory.", "This saves time in the access path for instruction references to the second-level cache.", "Additionally, the data Bus 382 is conditioned in the read direction.", "This minimizes the time penalty associated with reversing the direction of the data Bus.", "The data Bus is only required to be reversed when the cache replacement to the I-SLC Data RAM occurs.", "Drive control Circuits 384 and 386 control the direction of the data Bus 382, and Registers 388 and 390 respectively latch data to be written to and data read from the I-SLC Data RAMs. The operand second-level caches requires error code correction because it is operated as a post-store cache, and therefore, may have the most up-to-date data relative to the data in the memory.", "However, the time required for error code correction is compensated for by embedding the O-SLC Data RAM in the Data ASIC 354 and reducing off-chip crossings.", "The input address that drives the I-SLC Data RAMs 356 arrives from two sources.", "The set address is routed via Line 391 from the Data ASIC 284, and the block bits are routed to the I-SLC Data RAMs via Line 392 from the Address ASIC 352.", "The block bits provided on Line 392 are encoded by the Block Encode logic 393 according to the results of the Compare logic 364.", "If the address reference was a hit in the I-SLC Tag RAM, the particular block within the set which contains the requested address is identified by the block bits provided by Block Encode 393.", "FIG. 6 is a block diagram that illustrates the data path between the requesting processors, the second-level cache, and the memory.", "Segments 0-3 of the operand second-level cache and Segments 0-3 of the instruction second-level cache are shared between the I/O Subsystem, IPa, IPb, IPc, IPd, and the remote Address ASIC.", "There is also an access path to and from the Memory Subsystem (1 or 2).", "The data to and from these requesters is structured as separate read and write interfaces.", "Data is transferred to the Segments of the second-level cache from the requesters in either four or eight word packets.", "Data is always transferred to a requester from the second-level cache in eight word packets.", "Therefore it takes multiple clock cycles to transfer the information to or from the requesters.", "There is a four word data path to and from the O-SLC Segments 0-3 for each requester.", "The wide data path is cost effective because the data path is implemented using the dense routing capabilities of an ASIC and requires fewer cache cycles to handle each packet.", "There is only a two word interface from each of the IPs and remote requesters because the I-SLC Data RAM 356 is implemented with discreet SRAMs, and the ASICs have limited I/O capability.", "To handle the different sizes of interfaces, speed matching buffers were used at each requester interface.", "Specifically, Input Buffers 402, 404, 406, and 408 respectively handle input data from each of the local IPs, and Output Buffers 410, 412, 414, and 416 respectively handle output data to the local IPs.", "Input Buffers 418 and 420 respectively handle input data from the remote Segments 0 and 2 and Segments 1 and 3, and Output Buffers 422 and 424 respectively handle output data to the remote Segments 0 and 2 and Segments 1 and 3.", "Input Buffer 426 handles input data from the local I/O Subsystem, and Output Buffer 428 handles output data to the local I/O Subsystem.", "Finally, Input Buffer 430 handles input data from the local Memory Subsystem, and Output Buffer 432 handles output data to the local Memory Subsystem.", "FIG. 7 is a more detailed diagram of one of the O-SLC segments shown in FIG. 6. The operand second-level cache is a set associative caches with four blocks per set.", "The blocks are designated as Blocks 0-4.", "Single bit error correction and double bit error detection are provided with the ECC Generation logic circuit 422 and ECC Correction logic circuit 444.", "Corrected data is latched in the Correction Register 446.", "Feedback Path 448 is provided for read/update write operations.", "For read functions, both the O-SLC Tag RAM 360 and O-SLC Data RAM 357 are read together for each Block 0-3 using the set address information from the selected requester.", "The Hit Bits 449 from Compare logic circuit 366 are routed to Selector 370 of the Data ASIC 354 to select which block of data is to be routed to the respective Output Buffer 410, 412, 414, 416, 422, 424, 428, or 432.", "Selector 450 selects from the respective Input Buffers 402, 404, 406, 408, 418, 420, 426, or 430 data to be written to the O-SLC Data RAM 357 according to the selected request.", "Selector 452 selects between data on the feedback Path 448 and data from the Selector 450.", "The feedback Path 448 is used for read-modify-write operations such as for writing part of a word and for writing part of a cache block.", "Raw data that is read from the O-SLC Data RAM 357 is latched in the Raw Data Register 454.", "FIG. 8 is a more detailed diagram of the I-SLC segments shown in FIG. 6. The instruction second-level cache is implemented as a set associative cache with four blocks per set.", "However, unlike the operand second-level cache, the four blocks in each set of the instruction second-level cache are implemented within the I-SLC Data RAMs 356 and not with parallel block structures.", "This results in the look-up in the I-SLC Tag RAM 358 occurring before the reading of the I-SLC Data RAMs. The results of the Compare circuit 364 along with the input set address are used to address the I-SLC Data RAMs. The data interface to the I-SLC Data RAM 356 is bi-directional as shown by Line 382.", "This requires a tri-state output buffer control for both the Data ASIC 354 and the I-SLC Data RAM 356.", "After initialization the Output Buffer 462 is disabled by Output Drive Control logic circuit 464, and the Input Buffer 466 is enabled.", "Therefore, for the majority of the time, when the instruction second-level cache is performing read functions, there is no time penalty for reversing the direction of the Bus 382 because the Bus is already in the read direction.", "Only after a miss when a new block needs to be written into the I-SLC Data RAM 356, is the Input Buffer 466 disabled and the Output Buffer 462 enabled.", "After the line is written, the Output Drive Control 464 in the Data ASIC 354 and the corresponding drive control (not shown) in the I-SLC Data RAM reverse state, thereby returning to the preconditioned state.", "Instruction data to be written in the I-SLC Data RAM 356 is selected by Selector 468 from either the local Memory Subsystem as provided in the Input Buffers 430 or from the remote Segments as provided in a respective one of the Input Buffers 418 or 420.", "The selection is made based upon the request in process.", "FIG. 9 is a block diagram of the overall address path of the exemplary system.", "There is a single address interface from each of the local IPs, the local I/O Subsystem, and the remote Address ASIC (e.g., 102, 104, 108, or 110) as shown respectively by address Lines 502, 504, 506, 508, 510, and 512.", "The address interface branches off into respective Read Address Registers 514, 516, 518, 520, 522, and 524, and into respective Write Address Registers 526, 528, 530, 532, 534, and 536.", "This means that each requester can have a single read and a single write request outstanding to the second-level cache before being acknowledged.", "Generally, the acknowledgment comes when the second-level cache has completed as request, thereby letting the requester know that it can send another request.", "There are separate acknowledgments for read and write requests.", "After a request and its address are latched, the request and address are routed to one of the Segment Queues 542, 544, 546, or 548.", "There is a dedicated Segment Queue for each Segment 0-3 of the second-level cache.", "The Segment Queue to which the request is routed depends upon the requested address.", "Each of the Segments 0-3 operates independently and in parallel.", "That is, Segment 11 can be working on one request while Segment 1 is working on another request.", "Each of the Segments then selects an input request or a feedback request based upon the predetermined queuing priority and route the address to both the corresponding O-SLC Tag and the I-SLC Tag.", "FIG. 10 is a detailed block diagram of an O-SLC Tag logic circuit.", "The Segment Queue Address that is input on Line 602 is from a respective one of the Segment Queues 542, 544, 546 or 548.", "The set address field is routed to both the O-SLC Tag RAM 360 and to the O-SLC Data RAM 357.", "Set Address Register 604 latches the set address for the Data RAM.", "The second-level cache tag is divided into four parallel structures referenced as Block 0, Block 1, Block 2, and Block 3.", "Each Block consists of an embedded O-SLC Tag RAM 360, error correction logic, and compare logic.", "The Segment Queue Address 602 is divided into a set address provided on Line 606 and a block address that is provided on Line 608.", "The set address is used to address the O-SLC Tag RAMs 360, and the block address is used to compare against the information stored in the O-SLC Tag RAMs. If the block address matches data read from the O-SLC Tag RAMs, then the data requested is located in the O-SLC Data RAM 357 and can be accessed there rather than in either the local or remote Memory Subsystems.", "The O-SLC Tag RAMs 360 and the O-SLC Data RAM 357 are read in parallel, and the selection of the block is based on the results of the respective Compare logic circuits 610 that are stored in the respective Hit Registers 612.", "The respective outputs from the Hit Registers 612 are encoded by Encode logic 614 into Hit Bits 449 to select one of the blocks read from the O-SLC Data RAM if a hit occurs.", "Single bit error correction and double bit error detection are provided with the ECC Generation logic circuit 616 and ECC Correction logic circuit 618.", "Feedback Path 620 is provided for read/update write operations.", "Selector 622 selects between data resulting from read/update write operations and a Block Address 608.", "Write Register 624 latches a block address for writing it to the O-SLC Tag RAM 360, and Staging Register 626 stages the input Block Address 608 for comparing the input Block Address with data read from the O-SLC Tag RAM.", "FIG. 11 is a detailed block diagram of an I-SLC Tag logic circuit.", "The structure is essentially similar to the O-SLC Tag logic circuit of FIG. 10, except that them is no need for ECC correction.", "Parity detection, which is much faster and simpler, is used instead of ECC correction.", "If there is a parity error in an instruction mad from the second-level cache, the instruction may be read instead from the Memory 48.", "The Segment Queue Address that is input on Line 632 is from a respective one of the Segment Queues 542, 544, 546 or 548.", "The set address field is routed to both the I-SLC Tag RAM 358 and to the I-SLC Data RAMs 356.", "The second-level cache tag is divided into four parallel structures referenced as Block 0, Block 1, Block 2, and Block 3.", "Each Block consists of an embedded I-SLC Tag RAM 358 and compare logic.", "The Segment Queue Address 632 is divided into a set address provided on Line 634 and a block address that is provided on Line 636.", "The set address is used to address the respective I-SLC Tag RAMs 358, and the block address is used to compare against the information stored in the respective I-SLC Tag RAMs. If the block address matches data read from the I-SLC Tag RAMs, then the instruction requested is present in the second-level cache (one of the respective ISLC Data RAMs 356 and can be accessed there rather than in either the local or remote Memory Subsystems.", "Three registers are used to stage the set address 634 before forwarding it to the I-SLC Data RAM 356.", "The three staging registers are designated as Stage-0 Set Address Register 638, Stage-1 Set Address Register 640, and Stage-2 Set Address Register 642.", "The staging of the set address ensures that the timing of the arrival of the encoded hit Lines 644 matches that of the set address on Line 646.", "This is required because the blocks of the I-SLC Data RAMs are not separate RAM structures as for the O-SLC Data RAMs 357.", "The selection of the block is based on the results of the respective Compare logic circuits 648 that are stored in the respective Hit Registers 650.", "The respective outputs from the Hit Registers are encoded by Block Encode logic 393 into Hit Bits 644 to select a block to be read from the respective I-SLC Data RAM if a hit occurs.", "Parity errors are detected by Parity Check logic circuit 654.", "Feedback Path 656 is provided for read/update write operations.", "Selector 658 selects between a new address made available on Line 632, which is used to search the I-SLC Tag RAM 358, and the new replacement address on Line 656, which is used to write into the I-SLC Tag RAM after a cache miss.", "Write Register 660 latches a block address that is the new replacement address for writing into the respective I-SLC Tag RAM 358.", "Staging Register 662 stages the input Block Address 636 for comparing the input Block Address with data read from the I-SLC Tag RAM.", "In the exemplary system, the instruction second-level cache and operand second-level cache tag cycles operate in tandem.", "This simplifies maintaining cache coherency between the instruction and operand second-level caches.", "In addition, there is sufficient tag bandpass available to meet the request rate of all the requesters, with no significant performance loss relative to any speed advantage that might be obtained by operating the instruction and operation second-level cache tags as independent elements.", "However, it should be noted that the data portions of the instruction and operand second-level caches do not necessarily operate in tandem.", "This is because for a read, since the operand second-level cache is twice as wide as the instruction second-level cache, twice as many clock cycles are required by the instruction second-level cache to read a block.", "Therefore, a blocking scheme is used.", "The block scheme ensures that while the instruction second-level cache is reading data, future instruction second-level cache requests are blocked in the segment priority until the instruction second-level cache data read is complete.", "However, operand requests are allowed to flow into both the operand and instruction second-level cache tags when it is complete with its previous search.", "Having described an exemplary embodiment of the invention in the drawings and accompanying description, those skilled in the art will recognize that various modifications to the exemplary embodiment could be made without departing from the scope and spirit of the claims set forth below:" ]
PRIORITY CLAIM This application claims priority to European Patent Application No. 12305590.7, filed May 29, 2012, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which in its entirety are herein incorporated by reference. BACKGROUND OF THE INVENTION The present invention relates to propellers and, in particular, to propeller blades that include a rib in the spar core of the propeller blade. Modern propeller blades typically include root portions which extend into the hub arm of the hub of the propeller system and which are secured to and rotatable relative to the hub arm via a retention assembly. Typically the retention assembly includes one or a plurality of ball bearing assemblies which permit the rotation of the blade in the hub arm for accomplishing pitch change of the blade for altering the speed of the propeller and accordingly, the aircraft. The blades are typically formed by surrounding a foam spar core with a resin impregnated fabric. Leading and trailing edges of the blade are then formed over the fabric and surrounded by, for example, a Kevlar sock. Such blades are light and effective for their intended purposes. BRIEF DESCRIPTION OF THE INVENTION According to one embodiment, a propeller blade that includes a foam core having a groove formed therein, a fibrous material filling at least a portion of the groove and a structural layer that surrounds the fibrous material and at least a portion of the foam core is disclosed. In another embodiment, a method of forming a propeller blade that includes: forming a foam core, the form core including a groove formed therein; disposing a fibrous material in the groove; and forming a structural layer that surrounds fibrous material and a portion of the foam core is disclosed. BRIEF DESCRIPTION OF THE DRAWINGS The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: FIG. 1 is a plan-view of a propeller blade according to one embodiment of the present invention; FIG. 2 is a cross-section of the propeller blade shown in FIG. 1 ; FIG. 3 is a plan-view of a spar core having a groove formed therein; and FIG. 4 is a plan-view of the spar core of FIG. 3 with the groove filled with a fibrous material. DETAILED DESCRIPTION OF THE INVENTION Referring now to FIGS. 1 and 2 , plan and cross-section views of a propeller blade 100 according to one embodiment of the present invention are illustrated. For simplicity, the direction shown by arrow X shall be referred to as the span wise direction herein, the direction shown by arrow Y shall be referred to as the chord wise direction herein and the direction shown by arrow Z shall be referred to as the thickness direction or simply, the thickness. The cross-section shown in FIG. 2 is taken along line A-A. The blade 100 is formed by first forming a spar 102 . The spar 102 includes a spar foam core 104 (core) surrounded by a structural layer 106 . The core 104 is typically formed of a foam material that is injected into a mold to form a particular shape. In other embodiments, the core 104 could be machined to define the desired shape. The mold can include a layer of fiberglass or carbon (pre-preg) on the walls thereof to which the foam of the core 104 adheres. As such, the core 104 can be surrounded by a layer (not shown) of fiberglass or carbon in one embodiment but this is not required. The foam that forms the core 104 can be selected from one of: polyurethane (PU), polyisocyanurate, or polymethacrylimide (PMI). According to one embodiment, the blade 100 includes one or more ribs 105 formed in the spar foam core 104 . A more detailed explanation of the ribs 105 is provided below but, in general, the ribs 105 serve to provide stiffness in the thickness direction (e.g., from the camber 160 to the face 162 sides) of the propeller blade 100 . In more detail, a propeller blade with high activity factor and large chord wise lengths, has a lower ratio of stiffness in the chord wise direction as compared to stiffness in the span wise direction. When the curvatures of the camber 160 and face 162 sides of the blade 100 are high, secondary bending moments may be generated. The consequences of these secondary bending moments are large deformations and loadings in the direction perpendicular to the chord (e.g., in direction Z in FIG. 2 ). The ribs 105 can provide structure to reduce or avoid these deformations by locally raising inertia and stiffness of the chord wise direction Y of the spar 104 . The structural layer 106 is typically formed of a dry braided carbon fiber which is subsequently resin injected or a resin-impregnated fabric material (e.g. resin impregnated carbon fiber fabric) and disposed such that it surrounds the core 104 and the ribs 105 (and the fiberglass layer if it is included) by, for example, a braiding process. In one embodiment, the structural layer 106 is impregnated with a resin. In some cases, the spar 102 is heated to set the resin in the structural layer 106 . With the inclusion of the ribs 105 , the respective leading and trailing edges 115 , 116 of the spar 102 are kept in a fixed relation to one another. As such, the possibility of the core 104 cracking may be reduced. In some instances, the spar 102 is formed such that a portion of it surrounds a root portion 108 that allows the blade 100 to be connected to a hub (not shown). Rotation of the hub causes the blade 100 to rotate and, consequently, causes the generation of thrust to propel an aircraft. In the following discussion, it shall be assumed that the blade 100 rotates in the clockwise direction. The root portion 108 is sometimes referred to as a “tulip” in the industry and is typically formed of a metal. After the spar 102 is formed, leading edge foam 112 and trailing edge foam 114 are formed on the leading and trailing edges 115 , 116 respectively of the spar 102 . The leading edge foam 112 , trailing edge foam 114 and the spar 102 can then be encased in an outer layer 118 . The outer layer 118 can be formed of Kevlar and be in the form of a sock that is pulled over the assembly that includes the leading edge foam 112 , trailing edge foam 114 and the spar 102 . Of course, the outer layer 118 could be formed in other manners as well. FIG. 3 is a plan view of the camber side 160 of the spar core 104 that forms blade 100 . The spar core 104 includes a groove 300 formed therein. The groove 300 includes a width (w) and a depth (d) that extends into the page. The groove 300 can be formed in a many different manners. For instance, the groove 300 could be part of the mold into which the foam forming the spar core 104 is formed. In another embodiment, the spar core 104 is initially formed without the groove 300 and then the groove 300 is machined or otherwise formed in the core 104 . As illustrated, the groove 300 causes depressions in the leading and trailing edges 301 , 303 of the core 104 . Of course, the groove could be formed such that depressions are only formed in the camber 160 and face 162 sides. Referring now to FIG. 4 , the groove 300 has had one or more layers of a fibrous material 302 disposed therein. In one embodiment, the fibrous material 302 is a carbon fiber cloth. In one embodiment, the fibrous material 302 is formed of the same material as is used to form the structural layer 106 (e.g., a resin impregnated cloth or dry braided carbon fiber or cloth). The resin in the fibrous material 302 is eventually cured and the cured combination of the resin and the fibrous material 302 defines the ribs 105 shown in FIG. 1 . The fibrous material 302 could be placed in the groove 300 such that the camber 160 and face 162 sides (including the fibrous material 302 ) are substantially smooth. That is, the fibrous material 302 can fill the depth (d) of the groove 300 in one embodiment. It shall be understood, that the fibrous material 302 could be formed, for example, by braiding of dry carbon fibers in one embodiment. In another embodiment, the fibrous material 302 is a fibrous cloth and may include resin in it or not. Only one groove 300 has been shown in FIGS. 3-4 but that is by way of example, not limitation. The number and location of the grooves 300 is a matter of design choice that may be decided by the skill artisan after examination of this disclosure. In the manner described above, after the fibrous material 302 has been placed, the spar core 104 shown in FIG. 4 can have the structural layer 106 formed over it by first braiding a dry carbon fiber over the spar core 104 and fibrous material 302 . A resin can then be injected into the structural layer 106 and the fibrous material 302 . In this manner, the material can be made rigid and become the spar ribs 105 described above. While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while the various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
A propeller blade includes a foam core having a groove formed therein, a fibrous material filling at least a portion of the groove and a structural layer that surrounds the fibrous material and at least a portion of the foam core.
Concisely explain the essential features and purpose of the invention.
[ "PRIORITY CLAIM This application claims priority to European Patent Application No. 12305590.7, filed May 29, 2012, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which in its entirety are herein incorporated by reference.", "BACKGROUND OF THE INVENTION The present invention relates to propellers and, in particular, to propeller blades that include a rib in the spar core of the propeller blade.", "Modern propeller blades typically include root portions which extend into the hub arm of the hub of the propeller system and which are secured to and rotatable relative to the hub arm via a retention assembly.", "Typically the retention assembly includes one or a plurality of ball bearing assemblies which permit the rotation of the blade in the hub arm for accomplishing pitch change of the blade for altering the speed of the propeller and accordingly, the aircraft.", "The blades are typically formed by surrounding a foam spar core with a resin impregnated fabric.", "Leading and trailing edges of the blade are then formed over the fabric and surrounded by, for example, a Kevlar sock.", "Such blades are light and effective for their intended purposes.", "BRIEF DESCRIPTION OF THE INVENTION According to one embodiment, a propeller blade that includes a foam core having a groove formed therein, a fibrous material filling at least a portion of the groove and a structural layer that surrounds the fibrous material and at least a portion of the foam core is disclosed.", "In another embodiment, a method of forming a propeller blade that includes: forming a foam core, the form core including a groove formed therein;", "disposing a fibrous material in the groove;", "and forming a structural layer that surrounds fibrous material and a portion of the foam core is disclosed.", "BRIEF DESCRIPTION OF THE DRAWINGS The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification.", "The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: FIG. 1 is a plan-view of a propeller blade according to one embodiment of the present invention;", "FIG. 2 is a cross-section of the propeller blade shown in FIG. 1 ;", "FIG. 3 is a plan-view of a spar core having a groove formed therein;", "and FIG. 4 is a plan-view of the spar core of FIG. 3 with the groove filled with a fibrous material.", "DETAILED DESCRIPTION OF THE INVENTION Referring now to FIGS. 1 and 2 , plan and cross-section views of a propeller blade 100 according to one embodiment of the present invention are illustrated.", "For simplicity, the direction shown by arrow X shall be referred to as the span wise direction herein, the direction shown by arrow Y shall be referred to as the chord wise direction herein and the direction shown by arrow Z shall be referred to as the thickness direction or simply, the thickness.", "The cross-section shown in FIG. 2 is taken along line A-A.", "The blade 100 is formed by first forming a spar 102 .", "The spar 102 includes a spar foam core 104 (core) surrounded by a structural layer 106 .", "The core 104 is typically formed of a foam material that is injected into a mold to form a particular shape.", "In other embodiments, the core 104 could be machined to define the desired shape.", "The mold can include a layer of fiberglass or carbon (pre-preg) on the walls thereof to which the foam of the core 104 adheres.", "As such, the core 104 can be surrounded by a layer (not shown) of fiberglass or carbon in one embodiment but this is not required.", "The foam that forms the core 104 can be selected from one of: polyurethane (PU), polyisocyanurate, or polymethacrylimide (PMI).", "According to one embodiment, the blade 100 includes one or more ribs 105 formed in the spar foam core 104 .", "A more detailed explanation of the ribs 105 is provided below but, in general, the ribs 105 serve to provide stiffness in the thickness direction (e.g., from the camber 160 to the face 162 sides) of the propeller blade 100 .", "In more detail, a propeller blade with high activity factor and large chord wise lengths, has a lower ratio of stiffness in the chord wise direction as compared to stiffness in the span wise direction.", "When the curvatures of the camber 160 and face 162 sides of the blade 100 are high, secondary bending moments may be generated.", "The consequences of these secondary bending moments are large deformations and loadings in the direction perpendicular to the chord (e.g., in direction Z in FIG. 2 ).", "The ribs 105 can provide structure to reduce or avoid these deformations by locally raising inertia and stiffness of the chord wise direction Y of the spar 104 .", "The structural layer 106 is typically formed of a dry braided carbon fiber which is subsequently resin injected or a resin-impregnated fabric material (e.g. resin impregnated carbon fiber fabric) and disposed such that it surrounds the core 104 and the ribs 105 (and the fiberglass layer if it is included) by, for example, a braiding process.", "In one embodiment, the structural layer 106 is impregnated with a resin.", "In some cases, the spar 102 is heated to set the resin in the structural layer 106 .", "With the inclusion of the ribs 105 , the respective leading and trailing edges 115 , 116 of the spar 102 are kept in a fixed relation to one another.", "As such, the possibility of the core 104 cracking may be reduced.", "In some instances, the spar 102 is formed such that a portion of it surrounds a root portion 108 that allows the blade 100 to be connected to a hub (not shown).", "Rotation of the hub causes the blade 100 to rotate and, consequently, causes the generation of thrust to propel an aircraft.", "In the following discussion, it shall be assumed that the blade 100 rotates in the clockwise direction.", "The root portion 108 is sometimes referred to as a “tulip”", "in the industry and is typically formed of a metal.", "After the spar 102 is formed, leading edge foam 112 and trailing edge foam 114 are formed on the leading and trailing edges 115 , 116 respectively of the spar 102 .", "The leading edge foam 112 , trailing edge foam 114 and the spar 102 can then be encased in an outer layer 118 .", "The outer layer 118 can be formed of Kevlar and be in the form of a sock that is pulled over the assembly that includes the leading edge foam 112 , trailing edge foam 114 and the spar 102 .", "Of course, the outer layer 118 could be formed in other manners as well.", "FIG. 3 is a plan view of the camber side 160 of the spar core 104 that forms blade 100 .", "The spar core 104 includes a groove 300 formed therein.", "The groove 300 includes a width (w) and a depth (d) that extends into the page.", "The groove 300 can be formed in a many different manners.", "For instance, the groove 300 could be part of the mold into which the foam forming the spar core 104 is formed.", "In another embodiment, the spar core 104 is initially formed without the groove 300 and then the groove 300 is machined or otherwise formed in the core 104 .", "As illustrated, the groove 300 causes depressions in the leading and trailing edges 301 , 303 of the core 104 .", "Of course, the groove could be formed such that depressions are only formed in the camber 160 and face 162 sides.", "Referring now to FIG. 4 , the groove 300 has had one or more layers of a fibrous material 302 disposed therein.", "In one embodiment, the fibrous material 302 is a carbon fiber cloth.", "In one embodiment, the fibrous material 302 is formed of the same material as is used to form the structural layer 106 (e.g., a resin impregnated cloth or dry braided carbon fiber or cloth).", "The resin in the fibrous material 302 is eventually cured and the cured combination of the resin and the fibrous material 302 defines the ribs 105 shown in FIG. 1 .", "The fibrous material 302 could be placed in the groove 300 such that the camber 160 and face 162 sides (including the fibrous material 302 ) are substantially smooth.", "That is, the fibrous material 302 can fill the depth (d) of the groove 300 in one embodiment.", "It shall be understood, that the fibrous material 302 could be formed, for example, by braiding of dry carbon fibers in one embodiment.", "In another embodiment, the fibrous material 302 is a fibrous cloth and may include resin in it or not.", "Only one groove 300 has been shown in FIGS. 3-4 but that is by way of example, not limitation.", "The number and location of the grooves 300 is a matter of design choice that may be decided by the skill artisan after examination of this disclosure.", "In the manner described above, after the fibrous material 302 has been placed, the spar core 104 shown in FIG. 4 can have the structural layer 106 formed over it by first braiding a dry carbon fiber over the spar core 104 and fibrous material 302 .", "A resin can then be injected into the structural layer 106 and the fibrous material 302 .", "In this manner, the material can be made rigid and become the spar ribs 105 described above.", "While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments.", "Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention.", "Additionally, while the various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments.", "Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims." ]
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to transient voltage surge suppression systems, and in particular to a system and method for protecting transient-suppressing elements utilized in a transient voltage surge suppression system against over-voltage conditions. [0003] 2. Background Information [0004] Electrical systems, such as an electrical power distribution system, periodically experience over-voltage conditions. such as transient over-voltage conditions, also called “surges.” Over-voltage conditions are problematic to electrical systems because they may cause damage to the loads, such as an electronic device or other hardware, that are coupled thereto. As a result, transient voltage surge suppression (TVSS) systems have been developed to protect the loads from over-voltages that would otherwise damage the loads. TVSS systems typically provide such protection by coupling various types of known transient-suppressing elements between the phase, neutral and/or ground conductors of an electrical power distribution system. [0005] As is known in the art, transient-suppressing elements, such as metal-oxide varistors (MOVs), silicon avalanche diodes (SADs) and gas tubes, typically assume a high impedance state under normal operating voltages. When the voltage across a transient-suppressing element exceeds a pre-determined threshold rating, however, the impedance of the element drops dramatically, essentially short-circuiting the electrical conductors and “shunting” the current associated with the over-voltage through the transient-suppressing element and away from the load. [0006] MOVs are probably the most commonly used transient-suppressing elements. An MOV consists of two plates separated by an insulator, such as a metal oxide, that has a known voltage breakdown characteristic. When the voltage between the two plates reaches a certain level (the voltage breakdown level), the insulator breaks down and conducts current. MOVs, however, have operational limitations that must be taken into account when designing a TVSS system. Specifically, all MOVs have a maximum transient current rating that, if exceeded, may cause the MOV to fail. An MOV may also fail if subjected to repeated operation, even if the maximum transient current rating is never exceeded. The number of repeated operations necessary to cause failure is a function of the magnitude of transient current conducted by the MOV during each operation: the lower the magnitude, the greater the number of operations necessary to cause failure. [0007] In light of these limitations, prior art TVSS systems have been developed that use multiple MOVs in parallel combination such that the MOVs share the total transient current. Each individual MOV in such a configuration only conducts a portion of the total transient current, making it less likely that any individual MOV will exceed its maximum transient current capacity. In addition, a TVSS system that uses a plurality of parallel MOVs can withstand a greater number of operations because of the lower magnitude of transient current conducted by each individual MOV. Moreover, a parallel combination of MOVs is advantageous because the failure of any individual MOV will not cause a complete loss of TVSS system functionality. [0008] When an MOV fails, due to exceeding its maximum current rating or due to frequent operation, it initially falls into a low impedance state in which it draws a large steady-state current from the electrical system. This current, if not interrupted, will drive the MOV into a thermal runaway condition, typically resulting in an explosive failure of the MOV and damage to or destruction of the TVSS system as a whole. To avoid the explosive failure of MOVs in a TVSS system, appropriately-rated current-limiting elements, such as a fuse, are typically employed in series with MOVs, preferably with one such current-limiting element being in series with each MOV. Prior art TVSS systems employing multiple MOVs and one or more fuses are described in, for example, U.S. Pat. No. 5,153,806 to Corey, U.S. Pat. No. 4,271,466 to Comstock, U.S. Pat. No. 6,636,409 to Kladar et al., and U.S. Pat. No. 6,678,140 to Jakwani et al. [0009] The problem with using fuses to protect against MOV failure is that fuses, while effective in many conditions, are not reliable over the full range of fault currents that may occur. In particular, a fuse may open in response to certain over-current conditions (resulting from an over-voltage) that would not be a problem for (i.e., cause the failure of) the associated MOV. Such fuses are commonly referred to as “nuisance fuses” (having been opened under a condition that was not necessary to protect the MOV) and must be replaced, which is both expensive and inconvenient. Thus there is a need for a system for protecting transient-suppressing elements, such as MOVs, employed in a TVSS system from over-voltage conditions (and the over-currents that result therefrom) that is reliable over the full range of over-currents that may occur. SUMMARY OF THE INVENTION [0010] These needs, and others, are addressed by the present invention which provides a system for protecting a load connected to an electrical system from over-voltage conditions. The system includes a phase bus connected to a phase conductor of the electrical system and one or more transient-suppressing lines connected to the phase bus. Each of the transient-suppressing lines includes a contactor and a transient-suppressing element, such as an MOV, connected in series with the contactor. The system further includes a processing unit and a memory storing one or more routines executable by the processing unit. The contactor of each transient-suppressing line is in electronic communication with the processing unit, and the routines are adapted to selectively open and close each contactor, thereby protecting the associated transient suppressing element from excessive currents. [0011] In the preferred embodiment, each of the transient-suppressing lines has operatively coupled thereto at least one of: (i) a voltage transducer in electronic communication with the processing unit, the voltage transducer generating a voltage signal, and (ii) a current transducer in electronic communication with the processing unit, the current transducer generating a current signal. In this embodiment, the routines are further adapted to selectively open and close each contactor based on at least one of the associated voltage signal and the associated current signal. The memory may store one or both of a normal voltage signature and a normal current signature for each of the transient-suppressing lines. The routines may then be further adapted to open and close each contactor based on at least one of: (i) a first comparison between the associated voltage signal and the normal voltage signature, and (ii) a second comparison between the associated current signal and the normal current signature. In particular, the contactor will be opened is abnormal voltage and/or current conditions are detected. [0012] Moreover, the phase bus may include a phase bus contactor in electronic communication with the processing unit, wherein the routines are further adapted to selectively open and close the phase bus contactor. In particular, the phase bus may have operatively coupled thereto at least one of: (i) a phase bus voltage transducer in electronic communication with the processing unit, the phase bus voltage transducer generating a phase bus voltage signal, and (ii) a phase bus current transducer in electronic communication with the processing unit, the phase bus current transducer generating a phase bus current signal. In this configuration, the routines are further adapted to open and close the phase bus contactor based on at least one of the phase bus voltage signal and the phase bus current signal, such as by comparing those signals normal signatures to detect abnormalities. [0013] According to another aspect of the invention, a phase conductor voltage transducer generating a phase conductor voltage signal is operatively coupled to the phase conductor and in electronic communication with said processing unit. The phase bus contactor is in a normally open condition, and the routines are adapted to close the phase bus contactor only if the phase conductor voltage signal is determined to be at or below a predetermined level. [0014] According to yet another aspect of the invention, at least one of the transient-suppressing lines includes a parallel combination of a series contactor and a series transient-suppressing element which is connected in series with the transient-suppressing element of the transient-suppressing lines. The routines are adapted to selectively open and close said series contactor in order to provide greater voltage handling capability. [0015] The invention also relates to a method of protecting at least one transient-suppressing element from over-voltage conditions, wherein the at least one transient suppressing element is part of a system for protecting a load connected to an electrical system. The method includes providing a transient-suppressing line including the at least one transient-suppressing element, the transient-suppressing line being connected to the electrical system and being in parallel with the load, measuring at least one of a voltage signal representative of a voltage on the transient-suppressing line and a current signal representative of a current on the transient suppressing line, and selectively placing the transient-suppressing line in either an open, non-conducting condition or a closed, conducting condition based on at least one of the voltage signal and the current signal. As a result, the transient-suppressing element is protected form damaging over-voltage conditions. [0016] In one particular embodiment, the method includes storing one or both of a normal voltage signature and a normal current signature for the transient-suppressing line, and performing at least one of: (i) a first comparison between the voltage signal and the normal voltage signature, and (ii) a second comparison between the current signal and the normal current signature. In this embodiment, the step of selectively placing the transient-suppressing line in either an open, non-conducting condition or a closed, conducting condition is based on at least one of the first comparison and the second comparison. [0017] Where the transient-suppressing line is connected to a phase bus connected to a phase conductor of the electrical system, the method may include measuring at least one of a phase bus voltage signal representative of a voltage on the phase bus and a phase bus current signal representative of a current on the phase bus, and selectively placing the phase bus in either an open, non-conducting condition or a closed, conducting condition based on at least one of said phase bus voltage signal and said phase bus current signal. The decision to place the phase bus in either an open, non-conducting condition or a closed, conducting condition may be based on a comparison to normal voltage and current signatures to detect abnormal conditions. In addition, the method, according to another aspect of the invention, may include connecting the phase bus to a phase conductor of the electrical system only if a phase voltage on the phase conductor is determined to be at or below a predetermined level. Finally, the method may include selectively connecting at least one additional transient-suppressing element in series with the at least one transient-suppressing element to increase the voltage handling capacity. BRIEF DESCRIPTION OF THE DRAWINGS [0018] A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which: [0019] FIG. 1 is a schematic diagram of a TVSS system according to one embodiment of the present invention; [0020] FIGS. 2, 3 and 4 are graphical representations of sample normal and abnormal voltage and current signatures that may be measured using the TVSS system of FIG. 1 ; [0021] FIG. 5 is a schematic diagram that illustrates application of TVSS system of FIG. 1 to a three-phase electrical distribution system; and [0022] FIG. 6 is a schematic diagram of a TVSS system according to an alternate embodiment the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS [0023] FIG. 1 is a schematic diagram of a TVSS system 5 according to one embodiment of the present invention. TVSS system 5 is coupled to a phase conductor 10 , designated as Phase A, which is a phase conductor of an electrical power distribution system. Phase conductor 10 may be the sole phase conductor of a single phase electrical power distribution system, or one phase conductor of a multi-phase electrical power distribution system, such as, for example, a three-phase electrical power distribution system. TVSS system 5 includes TVSS circuit 15 in electronic communication with processing unit 20 , which may be, for instance, and without limitation, a microprocessor (μP). As seen in FIG. 1 , TVSS circuit 15 includes phase bus 25 that is selectively connectable to phase conductor 10 by way of contactor 30 . Contactor 30 may be any type of known electronically controlled switch or relay, such as a TRIAC or an SCR (silicon controlled rectifier). Contactor 30 , identified as K A in FIG. 1 , is in electronic communication with and under the control of processing unit 20 , which is able to selectively open and close contactor 30 using appropriate electronic signals represented by arrow 35 in FIG. 1 . [0024] In addition, a voltage transducer 40 , such as, for example, a potential transformer or similar voltage measuring device, is operatively coupled to phase conductor 10 and is in electronic communication with processing unit 20 . Voltage transducer 40 generates a signal V A which represents the voltage carried by phase conductor 10 (the source voltage). The V A signal is transmitted to processing unit 20 as indicated by the arrow 45 in FIG. 1 . A voltage transducer 50 is operatively coupled to phase bus 25 and is in electronic communication with processing unit 20 . Voltage transducer 50 generates a signal V a which represents the voltage carried by phase bus 25 . A current transducer 55 , such as, for example, a current transformer, a Hall Effect device or any other suitable current measuring device, is also operatively coupled to phase bus 25 and is in electronic communication with processing unit 20 . Current transducer 55 generates a signal I aT which represents the total current carried by phase bus 25 . The V a and I aT signals are transmitted to processing unit 20 as indicated by arrows 45 and 60 , respectively, in FIG. 1 . [0025] TVSS circuit 15 also includes a plurality of transient-suppressing lines 65 arranged in a parallel configuration as seen in FIG. 1 . Each transient-suppressing line 65 is connected to phase bus 25 at a first end thereof and to ground at a second end thereof. Transient-suppressing lines 65 are also connected in parallel with a load that is to be protected. Furthermore, each transient-suppressing line 65 includes a contactor 70 as described above (identified as K 1 , K 2 . . . K n ) and a transient-suppressing element 80 , which preferably is an MOV (identified as M 1 , M 2 . . . M n ), but may be another type of known transient-suppressing element. In addition, a voltage transducer 75 as described above and a current transducer 85 as described above are operatively coupled to each transient-suppressing line 65 . Each contactor 70 , voltage transducer 75 , and current transducer 85 is in electronic communication with processing unit 20 . Processing unit 20 , through appropriate electronic signals represented by arrow 35 , selectively controls the operation of (opening and closing) each contactor 70 . Each voltage transducer 75 generates a signal (V a1 , V a2 . . . V an ) which represents the voltage carried by the associated transient-suppressing line 65 (arrow 45 ), and each current transducer 85 generates a signal (I a1 , I a2 . . . I an ) which represents the current carried by the associated transient-suppressing line 65 (arrow 60 ). Those signals are communicated to processing unit 20 for processing thereby. [0026] Signals V A , V a , V a1 , V a2 . . . V an and I aT , I a1 , I a2 . . . I an not only provide information about a particular voltage or current level at a particular time, but also provide information and representations of the AC voltage and current waveforms that are present at each particular location in TVSS circuit 15 . In addition, as is known in the art, under normal, safe operating conditions, TVSS circuit 15 will have a consistent “normal” voltage signature (AC waveform) and a consistent “normal” current signature (AC waveform) at each location where signals V a , V a1 , V a2 . . . V an and I aT , I a1 , I a2 . . . I an are measured. FIG. 2 shows an example of a normal voltage signature 90 and a normal current signature 95 measured at, for example, the locations where V a1 and I a1 are measured. These signatures may be measured, recorded and stored in, for example, a memory 100 associated with processing unit 100 for use by processing unit 20 as described herein. Memory 100 may be one or more of any type of known storage element such as RAM, ROM, PROM and the like, alone or in combination. For example, memory 100 could be a combination of a RAM component and a ROM component. Under abnormal operating conditions, such as an over-voltage condition. the voltage signature and/or current signature at one or more of the locations where signals V a , V a1 , V a2 . . . V an and I aT , I a1 , I a2 . . . I an , are measured will differ from the normal current and/or voltage signature for that location. FIGS. 3 and 4 show two examples of a voltage signature ( 105 and 115 ) and a current signature ( 110 and 120 ) measured at the locations where V a1 and I a1 are measured under an abnormal operating condition, such as an over-voltage condition. Current signature 110 presents a phase shift as compared to normal current signature 95 due to microstructure damage of the associated transient-suppressing element 80 (e.g., MOV M 1 ) resulting from excessive joule heating. Similarly, current signature 120 presents a phase shift as compared to normal current signature 95 due to an over-voltage condition in the associated transient-suppressing line 65 . [0027] According to an aspect of the present invention, memory 100 is provided with one or more software routines executable by processing unit 20 for receiving the voltage and/or current signatures represented by signals V a , V a1 , V a2 . . . V an and I aT , I a1 , I a2 . . . I an and comparing them to the pre-stored normal voltage signature and normal current signature for the appropriate location within TVSS circuit 15 . Based on these comparisons, if one or more abnormal signatures are detected, processing unit 20 will generate and transmit an appropriate signal for opening the associated contact 70 to thereby protect the associated transient-suppressing element 80 from further exposure to a harmful voltage and/or current condition. As a result, damage, possibly catastrophic, to the TVSS circuit 15 as a whole will likely be prevented, with only the associated transient-suppressing element or elements 80 possibly needing to be replaced. As will be appreciated, under some circumstances, it will be advantageous to open contactor 30 to isolate TVSS circuit 15 (and protect all elements thereof) in its entirety until normal operating conditions are restored. [0028] According to a further aspect of the invention, when operation of TVSS circuit 15 is first initiated in a particular application, contactor 30 begins in a normally open condition, thereby isolating TVSS circuit 15 . Processing unit 20 will then monitor signal V A to determine whether it is within a predetermined normal operating range for TVSS circuit 15 , and will only generate a signal to close contactor 30 if it is determined that the signal V A is within the normal operating range. [0029] FIG. 5 illustrates the application of the present invention to a three-phase electrical distribution system having Phases A, B, and C. As seen in FIG. 5 , three TVSS circuits 15 as described above are provided, one for each of the Phases A, B and C. Processing unit 20 in this configuration is adapted to independently monitor each TVSS circuit 15 and take appropriate action as described above in connection with FIGS. 1-4 . [0030] FIG. 6 is a schematic diagram of a TVSS system 5 ′ according to an alternate embodiment of the present invention. As described below, TVSS system 5 ′ includes one or more additional series transient-suppressing elements that may be selectively switched in and out to provide increased operating voltage capability. TVSS system 5 ′ includes all of the elements of TVSS system 5 described above, and such elements are designated with like reference numerals in FIG. 6 . [0031] As seen in FIG. 6 , one or more of the transient-suppressing lines 65 in TVSS system 5 ′ include, in series with the other elements thereof, a parallel combination of a series transient-suppressing element 125 (identified as M s1 . . . M sn ) and a series contactor 130 (identified as K s1 . . . K sn ). In addition, a series current transducer 135 is operatively coupled to the line containing each series transient-suppressing element 125 to provide a signal (I sa1 . . . I san ) representative of the current flowing through the series transient-suppressing element 125 . Each series contactor 130 is in electronic communication with and under the selective control of processing unit 20 (represented by arrow 35 ′). Similarly, each series current transducer 135 is in electronic communication with processing unit 20 (represented by arrow 60 ′). If a series contactor 130 is in an open condition, then the associated series transient-suppressing element 125 will be by-passed. If, however, a series contactor 130 is in a closed condition, then the associated series transient-suppressing element 125 will be placed in series with the associated transient-suppressing element 80 , thereby increasing the voltage level that the transient-suppressing line 65 can handle. In this embodiment, memory 100 is provided with one or more routines for selectively opening and closing series contactors 130 when it would be desirable to increase the voltage that a particular transient-suppressing line 65 can handle. [0032] Thus, the present invention provides a system and method of providing transient voltage surge suppression in which the transient-suppressing elements that are utilized are protected over a full range of over-current conditions yet remain functional for all over-voltage conditions that they can appropriately handle (that may otherwise have caused a fuse to open). [0033] While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art of various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.
An over-voltage protection system including a phase bus connected to a phase conductor of an electrical system and one or more transient-suppressing lines connected to the phase bus. Each of the transient-suppressing lines includes a contactor and a transient-suppressing element. The contactor of each transient-suppressing line is selectively opened and closed by a processor, thereby protecting the transient suppressing element from excessive currents. Also a method of protecting at least one transient-suppressing element from over-voltage conditions including providing a transient-suppressing line including the at least one transient-suppressing element in parallel with a load, measuring at least one of a voltage signal representative of a voltage on the transient-suppressing line and a current signal representative of a current on the transient suppressing line, and selectively placing the transient-suppressin line in either an open condition or a closed condition based on at least one of the voltage signal and the current signal.
Identify the most important claim in the given context and summarize it
[ "BACKGROUND OF THE INVENTION [0001] 1.", "Field of the Invention [0002] The present invention relates to transient voltage surge suppression systems, and in particular to a system and method for protecting transient-suppressing elements utilized in a transient voltage surge suppression system against over-voltage conditions.", "[0003] 2.", "Background Information [0004] Electrical systems, such as an electrical power distribution system, periodically experience over-voltage conditions.", "such as transient over-voltage conditions, also called “surges.”", "Over-voltage conditions are problematic to electrical systems because they may cause damage to the loads, such as an electronic device or other hardware, that are coupled thereto.", "As a result, transient voltage surge suppression (TVSS) systems have been developed to protect the loads from over-voltages that would otherwise damage the loads.", "TVSS systems typically provide such protection by coupling various types of known transient-suppressing elements between the phase, neutral and/or ground conductors of an electrical power distribution system.", "[0005] As is known in the art, transient-suppressing elements, such as metal-oxide varistors (MOVs), silicon avalanche diodes (SADs) and gas tubes, typically assume a high impedance state under normal operating voltages.", "When the voltage across a transient-suppressing element exceeds a pre-determined threshold rating, however, the impedance of the element drops dramatically, essentially short-circuiting the electrical conductors and “shunting”", "the current associated with the over-voltage through the transient-suppressing element and away from the load.", "[0006] MOVs are probably the most commonly used transient-suppressing elements.", "An MOV consists of two plates separated by an insulator, such as a metal oxide, that has a known voltage breakdown characteristic.", "When the voltage between the two plates reaches a certain level (the voltage breakdown level), the insulator breaks down and conducts current.", "MOVs, however, have operational limitations that must be taken into account when designing a TVSS system.", "Specifically, all MOVs have a maximum transient current rating that, if exceeded, may cause the MOV to fail.", "An MOV may also fail if subjected to repeated operation, even if the maximum transient current rating is never exceeded.", "The number of repeated operations necessary to cause failure is a function of the magnitude of transient current conducted by the MOV during each operation: the lower the magnitude, the greater the number of operations necessary to cause failure.", "[0007] In light of these limitations, prior art TVSS systems have been developed that use multiple MOVs in parallel combination such that the MOVs share the total transient current.", "Each individual MOV in such a configuration only conducts a portion of the total transient current, making it less likely that any individual MOV will exceed its maximum transient current capacity.", "In addition, a TVSS system that uses a plurality of parallel MOVs can withstand a greater number of operations because of the lower magnitude of transient current conducted by each individual MOV.", "Moreover, a parallel combination of MOVs is advantageous because the failure of any individual MOV will not cause a complete loss of TVSS system functionality.", "[0008] When an MOV fails, due to exceeding its maximum current rating or due to frequent operation, it initially falls into a low impedance state in which it draws a large steady-state current from the electrical system.", "This current, if not interrupted, will drive the MOV into a thermal runaway condition, typically resulting in an explosive failure of the MOV and damage to or destruction of the TVSS system as a whole.", "To avoid the explosive failure of MOVs in a TVSS system, appropriately-rated current-limiting elements, such as a fuse, are typically employed in series with MOVs, preferably with one such current-limiting element being in series with each MOV.", "Prior art TVSS systems employing multiple MOVs and one or more fuses are described in, for example, U.S. Pat. No. 5,153,806 to Corey, U.S. Pat. No. 4,271,466 to Comstock, U.S. Pat. No. 6,636,409 to Kladar et al.", ", and U.S. Pat. No. 6,678,140 to Jakwani et al.", "[0009] The problem with using fuses to protect against MOV failure is that fuses, while effective in many conditions, are not reliable over the full range of fault currents that may occur.", "In particular, a fuse may open in response to certain over-current conditions (resulting from an over-voltage) that would not be a problem for (i.e., cause the failure of) the associated MOV.", "Such fuses are commonly referred to as “nuisance fuses”", "(having been opened under a condition that was not necessary to protect the MOV) and must be replaced, which is both expensive and inconvenient.", "Thus there is a need for a system for protecting transient-suppressing elements, such as MOVs, employed in a TVSS system from over-voltage conditions (and the over-currents that result therefrom) that is reliable over the full range of over-currents that may occur.", "SUMMARY OF THE INVENTION [0010] These needs, and others, are addressed by the present invention which provides a system for protecting a load connected to an electrical system from over-voltage conditions.", "The system includes a phase bus connected to a phase conductor of the electrical system and one or more transient-suppressing lines connected to the phase bus.", "Each of the transient-suppressing lines includes a contactor and a transient-suppressing element, such as an MOV, connected in series with the contactor.", "The system further includes a processing unit and a memory storing one or more routines executable by the processing unit.", "The contactor of each transient-suppressing line is in electronic communication with the processing unit, and the routines are adapted to selectively open and close each contactor, thereby protecting the associated transient suppressing element from excessive currents.", "[0011] In the preferred embodiment, each of the transient-suppressing lines has operatively coupled thereto at least one of: (i) a voltage transducer in electronic communication with the processing unit, the voltage transducer generating a voltage signal, and (ii) a current transducer in electronic communication with the processing unit, the current transducer generating a current signal.", "In this embodiment, the routines are further adapted to selectively open and close each contactor based on at least one of the associated voltage signal and the associated current signal.", "The memory may store one or both of a normal voltage signature and a normal current signature for each of the transient-suppressing lines.", "The routines may then be further adapted to open and close each contactor based on at least one of: (i) a first comparison between the associated voltage signal and the normal voltage signature, and (ii) a second comparison between the associated current signal and the normal current signature.", "In particular, the contactor will be opened is abnormal voltage and/or current conditions are detected.", "[0012] Moreover, the phase bus may include a phase bus contactor in electronic communication with the processing unit, wherein the routines are further adapted to selectively open and close the phase bus contactor.", "In particular, the phase bus may have operatively coupled thereto at least one of: (i) a phase bus voltage transducer in electronic communication with the processing unit, the phase bus voltage transducer generating a phase bus voltage signal, and (ii) a phase bus current transducer in electronic communication with the processing unit, the phase bus current transducer generating a phase bus current signal.", "In this configuration, the routines are further adapted to open and close the phase bus contactor based on at least one of the phase bus voltage signal and the phase bus current signal, such as by comparing those signals normal signatures to detect abnormalities.", "[0013] According to another aspect of the invention, a phase conductor voltage transducer generating a phase conductor voltage signal is operatively coupled to the phase conductor and in electronic communication with said processing unit.", "The phase bus contactor is in a normally open condition, and the routines are adapted to close the phase bus contactor only if the phase conductor voltage signal is determined to be at or below a predetermined level.", "[0014] According to yet another aspect of the invention, at least one of the transient-suppressing lines includes a parallel combination of a series contactor and a series transient-suppressing element which is connected in series with the transient-suppressing element of the transient-suppressing lines.", "The routines are adapted to selectively open and close said series contactor in order to provide greater voltage handling capability.", "[0015] The invention also relates to a method of protecting at least one transient-suppressing element from over-voltage conditions, wherein the at least one transient suppressing element is part of a system for protecting a load connected to an electrical system.", "The method includes providing a transient-suppressing line including the at least one transient-suppressing element, the transient-suppressing line being connected to the electrical system and being in parallel with the load, measuring at least one of a voltage signal representative of a voltage on the transient-suppressing line and a current signal representative of a current on the transient suppressing line, and selectively placing the transient-suppressing line in either an open, non-conducting condition or a closed, conducting condition based on at least one of the voltage signal and the current signal.", "As a result, the transient-suppressing element is protected form damaging over-voltage conditions.", "[0016] In one particular embodiment, the method includes storing one or both of a normal voltage signature and a normal current signature for the transient-suppressing line, and performing at least one of: (i) a first comparison between the voltage signal and the normal voltage signature, and (ii) a second comparison between the current signal and the normal current signature.", "In this embodiment, the step of selectively placing the transient-suppressing line in either an open, non-conducting condition or a closed, conducting condition is based on at least one of the first comparison and the second comparison.", "[0017] Where the transient-suppressing line is connected to a phase bus connected to a phase conductor of the electrical system, the method may include measuring at least one of a phase bus voltage signal representative of a voltage on the phase bus and a phase bus current signal representative of a current on the phase bus, and selectively placing the phase bus in either an open, non-conducting condition or a closed, conducting condition based on at least one of said phase bus voltage signal and said phase bus current signal.", "The decision to place the phase bus in either an open, non-conducting condition or a closed, conducting condition may be based on a comparison to normal voltage and current signatures to detect abnormal conditions.", "In addition, the method, according to another aspect of the invention, may include connecting the phase bus to a phase conductor of the electrical system only if a phase voltage on the phase conductor is determined to be at or below a predetermined level.", "Finally, the method may include selectively connecting at least one additional transient-suppressing element in series with the at least one transient-suppressing element to increase the voltage handling capacity.", "BRIEF DESCRIPTION OF THE DRAWINGS [0018] A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which: [0019] FIG. 1 is a schematic diagram of a TVSS system according to one embodiment of the present invention;", "[0020] FIGS. 2, 3 and 4 are graphical representations of sample normal and abnormal voltage and current signatures that may be measured using the TVSS system of FIG. 1 ;", "[0021] FIG. 5 is a schematic diagram that illustrates application of TVSS system of FIG. 1 to a three-phase electrical distribution system;", "and [0022] FIG. 6 is a schematic diagram of a TVSS system according to an alternate embodiment the present invention.", "DESCRIPTION OF THE PREFERRED EMBODIMENTS [0023] FIG. 1 is a schematic diagram of a TVSS system 5 according to one embodiment of the present invention.", "TVSS system 5 is coupled to a phase conductor 10 , designated as Phase A, which is a phase conductor of an electrical power distribution system.", "Phase conductor 10 may be the sole phase conductor of a single phase electrical power distribution system, or one phase conductor of a multi-phase electrical power distribution system, such as, for example, a three-phase electrical power distribution system.", "TVSS system 5 includes TVSS circuit 15 in electronic communication with processing unit 20 , which may be, for instance, and without limitation, a microprocessor (μP).", "As seen in FIG. 1 , TVSS circuit 15 includes phase bus 25 that is selectively connectable to phase conductor 10 by way of contactor 30 .", "Contactor 30 may be any type of known electronically controlled switch or relay, such as a TRIAC or an SCR (silicon controlled rectifier).", "Contactor 30 , identified as K A in FIG. 1 , is in electronic communication with and under the control of processing unit 20 , which is able to selectively open and close contactor 30 using appropriate electronic signals represented by arrow 35 in FIG. 1 .", "[0024] In addition, a voltage transducer 40 , such as, for example, a potential transformer or similar voltage measuring device, is operatively coupled to phase conductor 10 and is in electronic communication with processing unit 20 .", "Voltage transducer 40 generates a signal V A which represents the voltage carried by phase conductor 10 (the source voltage).", "The V A signal is transmitted to processing unit 20 as indicated by the arrow 45 in FIG. 1 .", "A voltage transducer 50 is operatively coupled to phase bus 25 and is in electronic communication with processing unit 20 .", "Voltage transducer 50 generates a signal V a which represents the voltage carried by phase bus 25 .", "A current transducer 55 , such as, for example, a current transformer, a Hall Effect device or any other suitable current measuring device, is also operatively coupled to phase bus 25 and is in electronic communication with processing unit 20 .", "Current transducer 55 generates a signal I aT which represents the total current carried by phase bus 25 .", "The V a and I aT signals are transmitted to processing unit 20 as indicated by arrows 45 and 60 , respectively, in FIG. 1 .", "[0025] TVSS circuit 15 also includes a plurality of transient-suppressing lines 65 arranged in a parallel configuration as seen in FIG. 1 .", "Each transient-suppressing line 65 is connected to phase bus 25 at a first end thereof and to ground at a second end thereof.", "Transient-suppressing lines 65 are also connected in parallel with a load that is to be protected.", "Furthermore, each transient-suppressing line 65 includes a contactor 70 as described above (identified as K 1 , K 2 .", "K n ) and a transient-suppressing element 80 , which preferably is an MOV (identified as M 1 , M 2 .", "M n ), but may be another type of known transient-suppressing element.", "In addition, a voltage transducer 75 as described above and a current transducer 85 as described above are operatively coupled to each transient-suppressing line 65 .", "Each contactor 70 , voltage transducer 75 , and current transducer 85 is in electronic communication with processing unit 20 .", "Processing unit 20 , through appropriate electronic signals represented by arrow 35 , selectively controls the operation of (opening and closing) each contactor 70 .", "Each voltage transducer 75 generates a signal (V a1 , V a2 .", "V an ) which represents the voltage carried by the associated transient-suppressing line 65 (arrow 45 ), and each current transducer 85 generates a signal (I a1 , I a2 .", "I an ) which represents the current carried by the associated transient-suppressing line 65 (arrow 60 ).", "Those signals are communicated to processing unit 20 for processing thereby.", "[0026] Signals V A , V a , V a1 , V a2 .", "V an and I aT , I a1 , I a2 .", "I an not only provide information about a particular voltage or current level at a particular time, but also provide information and representations of the AC voltage and current waveforms that are present at each particular location in TVSS circuit 15 .", "In addition, as is known in the art, under normal, safe operating conditions, TVSS circuit 15 will have a consistent “normal”", "voltage signature (AC waveform) and a consistent “normal”", "current signature (AC waveform) at each location where signals V a , V a1 , V a2 .", "V an and I aT , I a1 , I a2 .", "I an are measured.", "FIG. 2 shows an example of a normal voltage signature 90 and a normal current signature 95 measured at, for example, the locations where V a1 and I a1 are measured.", "These signatures may be measured, recorded and stored in, for example, a memory 100 associated with processing unit 100 for use by processing unit 20 as described herein.", "Memory 100 may be one or more of any type of known storage element such as RAM, ROM, PROM and the like, alone or in combination.", "For example, memory 100 could be a combination of a RAM component and a ROM component.", "Under abnormal operating conditions, such as an over-voltage condition.", "the voltage signature and/or current signature at one or more of the locations where signals V a , V a1 , V a2 .", "V an and I aT , I a1 , I a2 .", "I an , are measured will differ from the normal current and/or voltage signature for that location.", "FIGS. 3 and 4 show two examples of a voltage signature ( 105 and 115 ) and a current signature ( 110 and 120 ) measured at the locations where V a1 and I a1 are measured under an abnormal operating condition, such as an over-voltage condition.", "Current signature 110 presents a phase shift as compared to normal current signature 95 due to microstructure damage of the associated transient-suppressing element 80 (e.g., MOV M 1 ) resulting from excessive joule heating.", "Similarly, current signature 120 presents a phase shift as compared to normal current signature 95 due to an over-voltage condition in the associated transient-suppressing line 65 .", "[0027] According to an aspect of the present invention, memory 100 is provided with one or more software routines executable by processing unit 20 for receiving the voltage and/or current signatures represented by signals V a , V a1 , V a2 .", "V an and I aT , I a1 , I a2 .", "I an and comparing them to the pre-stored normal voltage signature and normal current signature for the appropriate location within TVSS circuit 15 .", "Based on these comparisons, if one or more abnormal signatures are detected, processing unit 20 will generate and transmit an appropriate signal for opening the associated contact 70 to thereby protect the associated transient-suppressing element 80 from further exposure to a harmful voltage and/or current condition.", "As a result, damage, possibly catastrophic, to the TVSS circuit 15 as a whole will likely be prevented, with only the associated transient-suppressing element or elements 80 possibly needing to be replaced.", "As will be appreciated, under some circumstances, it will be advantageous to open contactor 30 to isolate TVSS circuit 15 (and protect all elements thereof) in its entirety until normal operating conditions are restored.", "[0028] According to a further aspect of the invention, when operation of TVSS circuit 15 is first initiated in a particular application, contactor 30 begins in a normally open condition, thereby isolating TVSS circuit 15 .", "Processing unit 20 will then monitor signal V A to determine whether it is within a predetermined normal operating range for TVSS circuit 15 , and will only generate a signal to close contactor 30 if it is determined that the signal V A is within the normal operating range.", "[0029] FIG. 5 illustrates the application of the present invention to a three-phase electrical distribution system having Phases A, B, and C. As seen in FIG. 5 , three TVSS circuits 15 as described above are provided, one for each of the Phases A, B and C. Processing unit 20 in this configuration is adapted to independently monitor each TVSS circuit 15 and take appropriate action as described above in connection with FIGS. 1-4 .", "[0030] FIG. 6 is a schematic diagram of a TVSS system 5 ′ according to an alternate embodiment of the present invention.", "As described below, TVSS system 5 ′ includes one or more additional series transient-suppressing elements that may be selectively switched in and out to provide increased operating voltage capability.", "TVSS system 5 ′ includes all of the elements of TVSS system 5 described above, and such elements are designated with like reference numerals in FIG. 6 .", "[0031] As seen in FIG. 6 , one or more of the transient-suppressing lines 65 in TVSS system 5 ′ include, in series with the other elements thereof, a parallel combination of a series transient-suppressing element 125 (identified as M s1 .", "M sn ) and a series contactor 130 (identified as K s1 .", "K sn ).", "In addition, a series current transducer 135 is operatively coupled to the line containing each series transient-suppressing element 125 to provide a signal (I sa1 .", "I san ) representative of the current flowing through the series transient-suppressing element 125 .", "Each series contactor 130 is in electronic communication with and under the selective control of processing unit 20 (represented by arrow 35 ′).", "Similarly, each series current transducer 135 is in electronic communication with processing unit 20 (represented by arrow 60 ′).", "If a series contactor 130 is in an open condition, then the associated series transient-suppressing element 125 will be by-passed.", "If, however, a series contactor 130 is in a closed condition, then the associated series transient-suppressing element 125 will be placed in series with the associated transient-suppressing element 80 , thereby increasing the voltage level that the transient-suppressing line 65 can handle.", "In this embodiment, memory 100 is provided with one or more routines for selectively opening and closing series contactors 130 when it would be desirable to increase the voltage that a particular transient-suppressing line 65 can handle.", "[0032] Thus, the present invention provides a system and method of providing transient voltage surge suppression in which the transient-suppressing elements that are utilized are protected over a full range of over-current conditions yet remain functional for all over-voltage conditions that they can appropriately handle (that may otherwise have caused a fuse to open).", "[0033] While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art of various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure.", "Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof." ]
CROSS-REFERENCES TO RELATED APPLICATIONS [0001] The present application claims benefit under 35 USC 119(e) of U.S. provisional Application No. 60/863,536, filed on Oct. 30, 2006, entitled “Targeted Advertisement In The Digital Television Environment,” the content of which is incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION [0002] Television advertisements have traditionally used viewership statistics such as those provided by Nielsen ratings to select which advertisements to show during a given program. This method for reaching potential markets is far less precise than Internet advertisement, which uses available knowledge of the web surfer's preferences (i.e., search terms) and past viewing history to place advertisements in a targeted manner so that the most relevant advertisements are seen by the people most likely to be interested in the products and services being advertised. [0003] With the advent of digital television (DTV) standards such as DVB-H, Media-FLO™, T-DMB, and ISDB-T 1/3 segment, a wide range of mobile handset users and non-mobile digital television viewers become potential targets of advertisement. BRIEF SUMMARY OF THE INVENTION [0004] In accordance with one embodiment of the present invention, a method for targeted advertisement includes, in part, storing a profile tag associated with each user in a device maintained by that user. Each profile tag includes the demographic information of its associated user. A multitude of target tags each associated with an advertisement is also transmitted to the users. The target tags include the demographic information of the targeted users. The advertisements and their corresponding target tags are transmitted and cached in the devices maintained by the users. The number of matches between the target tags and the user profiles are supplied to their respective advertisers. The advertisers use the matching number to modify the prices they are willing to offer for the right to advertise during the commercial break. The target tags include information that is used to select one of the cached advertisement for playing in a commercial space or commercial break. [0005] In one embodiment, the advertisements are transmitted using a logical channel different than a logical channel used to broadcast regular programming. The logical channel used to transmit advertisement has a data rate lower than the data rate of the logical channel used to transmit regular programming. The regular programming interrupted during the commercial break is resumed in a time-shifted manner following the termination of the first commercial break. In another embodiment, the advertisement may be displayed on a portion of the screen simultaneously with the regular programming. [0006] In one embodiment, the played advertisement is stored in a cache and is periodically refreshed. The number of interactions between the user and the advertisement stored in the cache is tracked and supplied to the advertiser. In one embodiment, each profile tag further includes preference information supplied by its user in an optional survey. The preference information may be periodically updated in accordance with the user's behavior. In one embodiment, the number of matches for each advertisement is further defined by geographical locations of the users. [0007] In one embodiment, after playing the advertisement, a web browser is loaded to enable the user to access a web site to make an inquiry about the advertised product/service. In another embodiment, a phone number is automatically dialed to enable the user to make an inquiry about the advertised product/service. BRIEF DESCRIPTION OF THE DRAWINGS [0008] FIG. 1 is a high-level block diagram of an exemplary system adapted to deliver targeted advertisement in a digital television/video format, in accordance with one embodiment of the present invention. [0009] FIG. 2A shows a number of exemplary logical channels and time slots used for broadcasting regular programs as well as advertisements, in accordance with one embodiment of the present invention. [0010] FIG. 2B shows an exemplary time sequence according with which regular programs and advertisements are broadcast. [0011] FIG. 3 is a flowchart of steps used to cache an advertisement, in accordance with one embodiment of the present invention. [0012] FIG. 4 is a flowchart of steps used to cache an advertisement, in accordance with another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0013] In accordance with one embodiment of the present invention, targeted advertisements are delivered to mobile handset, such as cell phone users (subscribers), as well as to non-mobile digital television viewers in a manner that maximizes its effectiveness and potential benefits to the advertisers and the service providers. In one embodiment, the present invention enables the broadcast advertiser to deliver commercial information (advertisement) to targeted audiences in a timely manner that uses the broadcast bandwidth efficiently. The advertisement is stored and viewer feedback is provided, thus allowing the advertiser to consider the amount paid to the service provider for the advertisement and further to monitor the effectiveness of the advertisement. In one embodiment, the consideration of the amount paid by the advertiser is established through a bidding process carried out in real-time and based on feedbacks from the handsets. Accordingly, the present invention maximizes the value of the broadcast medium to both the advertisers and the broadcast service providers by enabling them, in part, to efficiently price and deliver the advertisements in a timely manner, as described further below. The following description applies equally to handheld mobile digital devices as well as to any other digital device capable of receiving and displaying digital video and audio data. [0014] FIG. 1 is a high-level block diagram of an exemplary system 100 adapted to deliver targeted advertisement in a digital television/video format, in accordance with one embodiment of the present invention. In this exemplary embodiment, advertisers 102 and service providers 104 negotiate to deliver advertisements to mobile handset or digital television receiver 150 . To achieve this and as described further below, in one embodiment, advertisers 102 compete for a commercial time slot and enter into a bidding process facilitated by auction server 106 . The advertiser with a winning bid secures the right to have its commercial played to the targeted users. In another embodiment, the advertiser who has paid a lock-in rate is accorded the time slot for its commercial. The lock-in rate could be fixed or float to match or exceed the highest bid. [0015] In accordance with one aspect of the present invention, the demographic information of the users as well as any preference information the user (hereinafter alternatively referred to herein as subscriber) provides, for example, in an optional a priori survey, is used to determine what advertisements to cache and/or play during a given commercial break. When the mobile handset device includes a location identifier, the user's location which is subject to dynamic changes, may also be used in this determination. Such demographic, geographic and preference information is referred to herein as tag data or tag profile, and is stored on the handset in a coded form when the handset is activated. The preference information may be updated over time with additional surveys or by passively monitoring the habits and behaviors of its respective subscriber. [0016] The advertiser or broadcaster attaches target tags to the advertisement; the tags contain characteristics of the target audience. As described further below, in one embodiment, an advertisement is played to a user when there is a match between the user's tag profile and the target tag included in the advertisement. Matching can be assessed by a variety of flexible algorithms such as detecting whether the least mean squared error between the advertisement tag and the subscriber's tag falls within a certain range. These algorithms can be set by the advertiser and run on the mobile handset device to identify which subscribers are most receptive to viewing the advertisement. Such an advertisement is referred to hereinbelow as a matched advertisement. A matched advertisement thus substantially increases the value of that advertisements to the advertiser by ensuring that it is viewed by an audience most likely to interact positively to it, and to make further inquiry and/or purchase the advertised product or service. At the same time, the broadcaster can sell the same time slot for an advertisement to several different advertisers targeting a viewing audience with a mix of tag profiles, thereby increasing the advertisement revenue. The target tag contains pricing information representing the amount the broadcaster has offered to pay for the advertisement. A previously cached advertisement can have its target tag replaced or modified to reflect price adjustments made by the advertiser. The pricing information is used to select one of the cached advertisements for playing during the designated commercial break. [0017] As is well known, in a television broadcast, advertisements are typically inserted during so-called commercial breaks which can last for some set period of time, such as 15 seconds or 30 seconds. Other breaks may also occur during broadcasts. For example, in some standards such as the DVB-H standard, there may be a delay (latency) between the time when the user selects a logical channel and the time when the selected channel content is displayed on the screen. In accordance with one embodiment of the present invention, the service provider inserts a matched advertisement during such a latency. The latency may occur upon initial selection of the logical channel or when switching between the channels occur. In some embodiments, additional latency is introduced to provide the time required to insert the advertisement. In other embodiments, advertisements are displayed on a small portion of the viewable area of the screen dedicated to advertising. [0018] In some embodiments, the advertisement matching, i.e., the comparison between the tag profile and the target tag, is performed on the handset. In yet other embodiments, the advertisement matching is performed using a server and a database remote to the handset. Such a remote matching may be carried out at the base station or anywhere on a network or the Internet that is coupled to the base station. For example, the advertisement matching may be done in a cable distribution head end where the video programming is distributed from. [0019] The broadcast network 104 transmits data containing the advertisements on one logical channel using advertisement server 112 while at the same time sending a live broadcast on another logical channel using content server 110 . The advertisement may thus be transmitted at a low data rate, thereby conserving broadcast bandwidth and also achieving greater reliability of data transmission, e.g. by using a higher coding rate for the advertisement data stream. The advertisement, presented to the user during commercial breaks, may be displayed in a separate area of the screen, or as a background image on the handset. It is understood that the advertisement may include audio, video, pictures, slideshows, etc. It is also understood that the advertisement may be intended for a particular program, a category of programs or any program the subscriber watches. [0020] In one embodiment, handset 150 includes an advertisement cache 152 and a subscriber cache 154 . The advertisement cache 152 is configured to store advertisement information (e.g. video, sound), that are automatically stored on the handset and displayed to the subscriber at the selected advertisement spot (commercial break). The subscriber cache 154 is content or advertisement which the subscriber selects for storage on the handset in order to view at a later time in a time-shifted manner. The size of each of the handset caches is programmable based upon the capabilities of the handset and other items stored therein. Such information may be stored remotely, i.e., outside the user's digital device to enable sending advertisements that are likely to fit in the cache. Any type of storage medium, e.g., static random access memory (SRAM), dynamic random access memory (DRAM), hard disk, flash memory, etc, may be used for caches. The stored advertisements, the interaction between the subscriber and the stored advertisement, the number of viewings of the advertisement, its dwell time, etc. may can be tracked and reported to the advertiser. [0021] A number of different algorithms or quantitative metrics may be used to determine the similarity and/or disparity between the user's tag profile and the target tag to determine if there is a match between the two and to decide whether to cache the advertisement or not. Such algorithms determine a matching score or a measure of similarity used to cache only the most relevant advertisements and discard those that are not. The amount of advertisement stored in the cache is used to determine how many advertisements to keep at any given time. [0022] An advertisement may have a number of versions each customized for a different demographic, handset location and cache size. For example, an older phone may get a slideshow instead of an animation or video. Also, a database containing geographical information may be used to preferentially display advertisements on handsets within a certain proximity to defined business locations offering the advertised product or service. [0023] FIG. 2A shows a number of exemplary logical channels and time slots used for broadcasting content (regular programming) as well as advertisements, in accordance with one embodiment of the present invention. Logical channels 1 , 2 and 3 are used for broadcasting during time slot 200 , and logical channels 4 , 5 and 6 are used for broadcasting during time slot 202 . FIG. 2B shows the time sequence according with which content and advertisements are broadcast. During period T 1 content is broadcast using logical channel 1 . During period T 2 when the commercial break occurs, the program is interrupted and the matched advertisement inserted earlier in the device is displayed to the user. During period T 3 the broadcasting of program resumes on a time shifted basis. [0024] Advertisers can also pay higher rates to ensure their ads are preferentially cached when competing for the same commercial breaks. Assume, for example, that two or more advertisements intended for broadcast during a particular commercial break are matched to a group of users. To secure the right to advertisement during a commercial break, the advertisers enter into a bidding contest and bid up their offers until the advertiser whose offer is accepted secured the right to broadcast its advertisement during that break. In one embodiment, the bidding adjustment is carried out in real time—to increase the likelihood that the advertisement is cached—based on the feedback that the advertiser receives, as described further below. [0025] Referring to FIG. 1 , standards such as DVB-H and Media FLO, include provisions for a reverse channel 116 , which enable the user to send data back to the broadcaster through the handset's mobile phone data link, e.g., GSM, EDGE, WCDMA or other physical layers). In accordance with one embodiment of the present invention, the reverse channel 116 is used, in part, to provide real-time feedback to the advertiser regarding the number of subscriber tag profiles that have matched an advertisement's target tag for any given commercial break, and/or provide feedback regarding the location of the subscriber handsets/terminals. As described above, an advertiser may, in response to the feedback, change the advertisement, offer to pay a higher rate or a better financial package for the right to broadcast the commercial during the target commercial break so as to increase the rate at which the advertisement is cached. The bidding may can continue until the commercial break occurs. As also described above, in some embodiments, the advertiser who has paid a lock-in rate is accorded the time slot for its commercial. The lock-in rate may be fixed or float to match or exceed the highest bid. Advertisers may be charged based on the frequency that their bids win matches as well as the particular times during which the advertisement is scheduled to be broadcast. For example, the cost for advertisement varies depending on the time of the day or the programs during which the advertisement(s) is scheduled to be played. [0026] FIG. 3 is a flowchart 300 of steps used to cache an advertisement, in accordance with one embodiment of the present invention. The advertisement is received 302 via a broadcast channel. Next, a matching operation 304 , using any one of a number of algorithms or a quantitative metrics, is performed to determine whether a match exists between the subscriber's profile tag and the target tag of the advertisement. If an acceptable match is not detected 308 , the advertisement is discarded and thus is not cached. If an acceptable match is detected 304 , and the advertiser has an offer that is accepted or the advertiser has a lock-in rate 306 , the advertisement is cached 314 and a corresponding notification is sent to the service provider via a reverse channel. If an acceptable match is detected 304 but the advertiser's offer is not accepted by the service provider, the advertisement is discarded 310 and a corresponding notification is sent to the service provider via the reverse channel. [0027] Assuming an agreement is reached between the advertiser and the service provider, after the advertisement is played 316 , if the user chooses not to interact 324 with the played advertisement, the user is provided with an option to save the advertisement 324 . The advertisement is either discarded 322 or is saved 324 in the subscriber cache, depending on the user's selected option. The user may select to act upon the viewed commercial 318 . If the user so selects, in one embodiment, a web browser is loaded to enable the user to make additional inquiries about, or to attempt to purchase, the advertised product/service from the advertiser or related companies. The web access may be carried out to keep a count of the activity and the tag profile of the user making the web access. To maintain the subscriber's privacy, the identity of the subscriber is disassociated from his/her profile. In another embodiment, in response to the user's selection 318 , a phone number is dialed to enable the user to make additional inquiries about, or to attempt to purchase, the advertised product/service. [0028] FIG. 4 is a flowchart 400 of steps used to bid for an advertisement to be viewed during a commercial break, in accordance with another embodiment of the present invention. The advertiser offers to pay 402 a basic fee to have its advertisement viewed. The service provider receives the offer price and transmits 404 the advertisement. Thereafter, the number of users whose tag profiles match the target tag of that advertisement is determined and fed back 406 to the advertiser. The advertiser is thus enabled to adjust the offer price based on the number of matches until the advertisement is played 408 . The advertiser pays a final rate 410 based on the number of advertisements that are cached and viewed. [0029] In some embodiments, the advertisements are inserted at a frequency determined entirely by the subscription rate that the viewer is paying. This allows the viewer to trade off subscription cost for the convenience of advertisement-free viewing. To achieve this, in one embodiment, the service provider can broadcast a given program over a channel continuously without inserting any commercial breaks. The handset, based on a subscriber's level of payments, is adapted to select the frequency with which commercial breaks occur and insert a matching advertisement by retrieving it from the viewer's advertisement cache. While the advertisement is being displayed, the regular programming is stored in a buffer which is thereafter retrieved and played in a time-shifted manner and after the advertisement is played. [0030] Such embodiment may be used in demographic segments that are relatively more price sensitive and are willing to endure more frequent commercial breaks in order to reduce their monthly subscription rates. The advertisement frequency is determined using the information stored in the handset related to subscription rates. The subscriber may choose to watch certain programs and channels without advertising by paying an additional amount over a subscription that would normally have the advertisement. [0031] Some embodiments of the present invention may credit the user for watching certain advertisement and to reduce the occurrence of future advertisements as a consequence. For example, a played long infomercial may allow one or more future programs to have no or a relatively reduced number of advertisements. A positive reaction by the subscriber to a viewed advertisement that leads to a call to advertiser or to a loading of an advertiser's web page may also accumulate credits. Accordingly, in such embodiments, enhanced exposure to advertisements provides credits toward viewing future commercial-free programs. [0032] The above embodiments of the present invention are illustrative and not limiting. Various alternatives and equivalents are possible. The invention is not limited by the type of digital device, mobile, etc. used for targeted advertisement. The invention is not limited by the rate used to transfer the data. Other additions, subtractions or modifications are obvious in view of the present disclosure and are intended to fall within the scope of the appended claims.
A method for targeted advertisement includes storing a profile tag associated with each user in a device maintained by that user. Each profile tag includes the demographic information of its associated user. A multitude of target tags are also transmitted to the users. Each target tag is associated with an advertiser and includes the demographic information of the users. The advertisements and their corresponding target tags are transmitted and cached in the devices maintained by the users. The number of matches between the target tags and the user profiles are supplied to their respective advertisers. The advertisers use the matching number to modify the prices they are willing to offer for the commercial break. The target tags include information that is used to select one of the cached advertisement for playing during the commercial break.
Provide a concise summary of the essential information conveyed in the given context.
[ "CROSS-REFERENCES TO RELATED APPLICATIONS [0001] The present application claims benefit under 35 USC 119(e) of U.S. provisional Application No. 60/863,536, filed on Oct. 30, 2006, entitled “Targeted Advertisement In The Digital Television Environment,” the content of which is incorporated herein by reference in its entirety.", "BACKGROUND OF THE INVENTION [0002] Television advertisements have traditionally used viewership statistics such as those provided by Nielsen ratings to select which advertisements to show during a given program.", "This method for reaching potential markets is far less precise than Internet advertisement, which uses available knowledge of the web surfer's preferences (i.e., search terms) and past viewing history to place advertisements in a targeted manner so that the most relevant advertisements are seen by the people most likely to be interested in the products and services being advertised.", "[0003] With the advent of digital television (DTV) standards such as DVB-H, Media-FLO™, T-DMB, and ISDB-T 1/3 segment, a wide range of mobile handset users and non-mobile digital television viewers become potential targets of advertisement.", "BRIEF SUMMARY OF THE INVENTION [0004] In accordance with one embodiment of the present invention, a method for targeted advertisement includes, in part, storing a profile tag associated with each user in a device maintained by that user.", "Each profile tag includes the demographic information of its associated user.", "A multitude of target tags each associated with an advertisement is also transmitted to the users.", "The target tags include the demographic information of the targeted users.", "The advertisements and their corresponding target tags are transmitted and cached in the devices maintained by the users.", "The number of matches between the target tags and the user profiles are supplied to their respective advertisers.", "The advertisers use the matching number to modify the prices they are willing to offer for the right to advertise during the commercial break.", "The target tags include information that is used to select one of the cached advertisement for playing in a commercial space or commercial break.", "[0005] In one embodiment, the advertisements are transmitted using a logical channel different than a logical channel used to broadcast regular programming.", "The logical channel used to transmit advertisement has a data rate lower than the data rate of the logical channel used to transmit regular programming.", "The regular programming interrupted during the commercial break is resumed in a time-shifted manner following the termination of the first commercial break.", "In another embodiment, the advertisement may be displayed on a portion of the screen simultaneously with the regular programming.", "[0006] In one embodiment, the played advertisement is stored in a cache and is periodically refreshed.", "The number of interactions between the user and the advertisement stored in the cache is tracked and supplied to the advertiser.", "In one embodiment, each profile tag further includes preference information supplied by its user in an optional survey.", "The preference information may be periodically updated in accordance with the user's behavior.", "In one embodiment, the number of matches for each advertisement is further defined by geographical locations of the users.", "[0007] In one embodiment, after playing the advertisement, a web browser is loaded to enable the user to access a web site to make an inquiry about the advertised product/service.", "In another embodiment, a phone number is automatically dialed to enable the user to make an inquiry about the advertised product/service.", "BRIEF DESCRIPTION OF THE DRAWINGS [0008] FIG. 1 is a high-level block diagram of an exemplary system adapted to deliver targeted advertisement in a digital television/video format, in accordance with one embodiment of the present invention.", "[0009] FIG. 2A shows a number of exemplary logical channels and time slots used for broadcasting regular programs as well as advertisements, in accordance with one embodiment of the present invention.", "[0010] FIG. 2B shows an exemplary time sequence according with which regular programs and advertisements are broadcast.", "[0011] FIG. 3 is a flowchart of steps used to cache an advertisement, in accordance with one embodiment of the present invention.", "[0012] FIG. 4 is a flowchart of steps used to cache an advertisement, in accordance with another embodiment of the present invention.", "DETAILED DESCRIPTION OF THE INVENTION [0013] In accordance with one embodiment of the present invention, targeted advertisements are delivered to mobile handset, such as cell phone users (subscribers), as well as to non-mobile digital television viewers in a manner that maximizes its effectiveness and potential benefits to the advertisers and the service providers.", "In one embodiment, the present invention enables the broadcast advertiser to deliver commercial information (advertisement) to targeted audiences in a timely manner that uses the broadcast bandwidth efficiently.", "The advertisement is stored and viewer feedback is provided, thus allowing the advertiser to consider the amount paid to the service provider for the advertisement and further to monitor the effectiveness of the advertisement.", "In one embodiment, the consideration of the amount paid by the advertiser is established through a bidding process carried out in real-time and based on feedbacks from the handsets.", "Accordingly, the present invention maximizes the value of the broadcast medium to both the advertisers and the broadcast service providers by enabling them, in part, to efficiently price and deliver the advertisements in a timely manner, as described further below.", "The following description applies equally to handheld mobile digital devices as well as to any other digital device capable of receiving and displaying digital video and audio data.", "[0014] FIG. 1 is a high-level block diagram of an exemplary system 100 adapted to deliver targeted advertisement in a digital television/video format, in accordance with one embodiment of the present invention.", "In this exemplary embodiment, advertisers 102 and service providers 104 negotiate to deliver advertisements to mobile handset or digital television receiver 150 .", "To achieve this and as described further below, in one embodiment, advertisers 102 compete for a commercial time slot and enter into a bidding process facilitated by auction server 106 .", "The advertiser with a winning bid secures the right to have its commercial played to the targeted users.", "In another embodiment, the advertiser who has paid a lock-in rate is accorded the time slot for its commercial.", "The lock-in rate could be fixed or float to match or exceed the highest bid.", "[0015] In accordance with one aspect of the present invention, the demographic information of the users as well as any preference information the user (hereinafter alternatively referred to herein as subscriber) provides, for example, in an optional a priori survey, is used to determine what advertisements to cache and/or play during a given commercial break.", "When the mobile handset device includes a location identifier, the user's location which is subject to dynamic changes, may also be used in this determination.", "Such demographic, geographic and preference information is referred to herein as tag data or tag profile, and is stored on the handset in a coded form when the handset is activated.", "The preference information may be updated over time with additional surveys or by passively monitoring the habits and behaviors of its respective subscriber.", "[0016] The advertiser or broadcaster attaches target tags to the advertisement;", "the tags contain characteristics of the target audience.", "As described further below, in one embodiment, an advertisement is played to a user when there is a match between the user's tag profile and the target tag included in the advertisement.", "Matching can be assessed by a variety of flexible algorithms such as detecting whether the least mean squared error between the advertisement tag and the subscriber's tag falls within a certain range.", "These algorithms can be set by the advertiser and run on the mobile handset device to identify which subscribers are most receptive to viewing the advertisement.", "Such an advertisement is referred to hereinbelow as a matched advertisement.", "A matched advertisement thus substantially increases the value of that advertisements to the advertiser by ensuring that it is viewed by an audience most likely to interact positively to it, and to make further inquiry and/or purchase the advertised product or service.", "At the same time, the broadcaster can sell the same time slot for an advertisement to several different advertisers targeting a viewing audience with a mix of tag profiles, thereby increasing the advertisement revenue.", "The target tag contains pricing information representing the amount the broadcaster has offered to pay for the advertisement.", "A previously cached advertisement can have its target tag replaced or modified to reflect price adjustments made by the advertiser.", "The pricing information is used to select one of the cached advertisements for playing during the designated commercial break.", "[0017] As is well known, in a television broadcast, advertisements are typically inserted during so-called commercial breaks which can last for some set period of time, such as 15 seconds or 30 seconds.", "Other breaks may also occur during broadcasts.", "For example, in some standards such as the DVB-H standard, there may be a delay (latency) between the time when the user selects a logical channel and the time when the selected channel content is displayed on the screen.", "In accordance with one embodiment of the present invention, the service provider inserts a matched advertisement during such a latency.", "The latency may occur upon initial selection of the logical channel or when switching between the channels occur.", "In some embodiments, additional latency is introduced to provide the time required to insert the advertisement.", "In other embodiments, advertisements are displayed on a small portion of the viewable area of the screen dedicated to advertising.", "[0018] In some embodiments, the advertisement matching, i.e., the comparison between the tag profile and the target tag, is performed on the handset.", "In yet other embodiments, the advertisement matching is performed using a server and a database remote to the handset.", "Such a remote matching may be carried out at the base station or anywhere on a network or the Internet that is coupled to the base station.", "For example, the advertisement matching may be done in a cable distribution head end where the video programming is distributed from.", "[0019] The broadcast network 104 transmits data containing the advertisements on one logical channel using advertisement server 112 while at the same time sending a live broadcast on another logical channel using content server 110 .", "The advertisement may thus be transmitted at a low data rate, thereby conserving broadcast bandwidth and also achieving greater reliability of data transmission, e.g. by using a higher coding rate for the advertisement data stream.", "The advertisement, presented to the user during commercial breaks, may be displayed in a separate area of the screen, or as a background image on the handset.", "It is understood that the advertisement may include audio, video, pictures, slideshows, etc.", "It is also understood that the advertisement may be intended for a particular program, a category of programs or any program the subscriber watches.", "[0020] In one embodiment, handset 150 includes an advertisement cache 152 and a subscriber cache 154 .", "The advertisement cache 152 is configured to store advertisement information (e.g. video, sound), that are automatically stored on the handset and displayed to the subscriber at the selected advertisement spot (commercial break).", "The subscriber cache 154 is content or advertisement which the subscriber selects for storage on the handset in order to view at a later time in a time-shifted manner.", "The size of each of the handset caches is programmable based upon the capabilities of the handset and other items stored therein.", "Such information may be stored remotely, i.e., outside the user's digital device to enable sending advertisements that are likely to fit in the cache.", "Any type of storage medium, e.g., static random access memory (SRAM), dynamic random access memory (DRAM), hard disk, flash memory, etc, may be used for caches.", "The stored advertisements, the interaction between the subscriber and the stored advertisement, the number of viewings of the advertisement, its dwell time, etc.", "may can be tracked and reported to the advertiser.", "[0021] A number of different algorithms or quantitative metrics may be used to determine the similarity and/or disparity between the user's tag profile and the target tag to determine if there is a match between the two and to decide whether to cache the advertisement or not.", "Such algorithms determine a matching score or a measure of similarity used to cache only the most relevant advertisements and discard those that are not.", "The amount of advertisement stored in the cache is used to determine how many advertisements to keep at any given time.", "[0022] An advertisement may have a number of versions each customized for a different demographic, handset location and cache size.", "For example, an older phone may get a slideshow instead of an animation or video.", "Also, a database containing geographical information may be used to preferentially display advertisements on handsets within a certain proximity to defined business locations offering the advertised product or service.", "[0023] FIG. 2A shows a number of exemplary logical channels and time slots used for broadcasting content (regular programming) as well as advertisements, in accordance with one embodiment of the present invention.", "Logical channels 1 , 2 and 3 are used for broadcasting during time slot 200 , and logical channels 4 , 5 and 6 are used for broadcasting during time slot 202 .", "FIG. 2B shows the time sequence according with which content and advertisements are broadcast.", "During period T 1 content is broadcast using logical channel 1 .", "During period T 2 when the commercial break occurs, the program is interrupted and the matched advertisement inserted earlier in the device is displayed to the user.", "During period T 3 the broadcasting of program resumes on a time shifted basis.", "[0024] Advertisers can also pay higher rates to ensure their ads are preferentially cached when competing for the same commercial breaks.", "Assume, for example, that two or more advertisements intended for broadcast during a particular commercial break are matched to a group of users.", "To secure the right to advertisement during a commercial break, the advertisers enter into a bidding contest and bid up their offers until the advertiser whose offer is accepted secured the right to broadcast its advertisement during that break.", "In one embodiment, the bidding adjustment is carried out in real time—to increase the likelihood that the advertisement is cached—based on the feedback that the advertiser receives, as described further below.", "[0025] Referring to FIG. 1 , standards such as DVB-H and Media FLO, include provisions for a reverse channel 116 , which enable the user to send data back to the broadcaster through the handset's mobile phone data link, e.g., GSM, EDGE, WCDMA or other physical layers).", "In accordance with one embodiment of the present invention, the reverse channel 116 is used, in part, to provide real-time feedback to the advertiser regarding the number of subscriber tag profiles that have matched an advertisement's target tag for any given commercial break, and/or provide feedback regarding the location of the subscriber handsets/terminals.", "As described above, an advertiser may, in response to the feedback, change the advertisement, offer to pay a higher rate or a better financial package for the right to broadcast the commercial during the target commercial break so as to increase the rate at which the advertisement is cached.", "The bidding may can continue until the commercial break occurs.", "As also described above, in some embodiments, the advertiser who has paid a lock-in rate is accorded the time slot for its commercial.", "The lock-in rate may be fixed or float to match or exceed the highest bid.", "Advertisers may be charged based on the frequency that their bids win matches as well as the particular times during which the advertisement is scheduled to be broadcast.", "For example, the cost for advertisement varies depending on the time of the day or the programs during which the advertisement(s) is scheduled to be played.", "[0026] FIG. 3 is a flowchart 300 of steps used to cache an advertisement, in accordance with one embodiment of the present invention.", "The advertisement is received 302 via a broadcast channel.", "Next, a matching operation 304 , using any one of a number of algorithms or a quantitative metrics, is performed to determine whether a match exists between the subscriber's profile tag and the target tag of the advertisement.", "If an acceptable match is not detected 308 , the advertisement is discarded and thus is not cached.", "If an acceptable match is detected 304 , and the advertiser has an offer that is accepted or the advertiser has a lock-in rate 306 , the advertisement is cached 314 and a corresponding notification is sent to the service provider via a reverse channel.", "If an acceptable match is detected 304 but the advertiser's offer is not accepted by the service provider, the advertisement is discarded 310 and a corresponding notification is sent to the service provider via the reverse channel.", "[0027] Assuming an agreement is reached between the advertiser and the service provider, after the advertisement is played 316 , if the user chooses not to interact 324 with the played advertisement, the user is provided with an option to save the advertisement 324 .", "The advertisement is either discarded 322 or is saved 324 in the subscriber cache, depending on the user's selected option.", "The user may select to act upon the viewed commercial 318 .", "If the user so selects, in one embodiment, a web browser is loaded to enable the user to make additional inquiries about, or to attempt to purchase, the advertised product/service from the advertiser or related companies.", "The web access may be carried out to keep a count of the activity and the tag profile of the user making the web access.", "To maintain the subscriber's privacy, the identity of the subscriber is disassociated from his/her profile.", "In another embodiment, in response to the user's selection 318 , a phone number is dialed to enable the user to make additional inquiries about, or to attempt to purchase, the advertised product/service.", "[0028] FIG. 4 is a flowchart 400 of steps used to bid for an advertisement to be viewed during a commercial break, in accordance with another embodiment of the present invention.", "The advertiser offers to pay 402 a basic fee to have its advertisement viewed.", "The service provider receives the offer price and transmits 404 the advertisement.", "Thereafter, the number of users whose tag profiles match the target tag of that advertisement is determined and fed back 406 to the advertiser.", "The advertiser is thus enabled to adjust the offer price based on the number of matches until the advertisement is played 408 .", "The advertiser pays a final rate 410 based on the number of advertisements that are cached and viewed.", "[0029] In some embodiments, the advertisements are inserted at a frequency determined entirely by the subscription rate that the viewer is paying.", "This allows the viewer to trade off subscription cost for the convenience of advertisement-free viewing.", "To achieve this, in one embodiment, the service provider can broadcast a given program over a channel continuously without inserting any commercial breaks.", "The handset, based on a subscriber's level of payments, is adapted to select the frequency with which commercial breaks occur and insert a matching advertisement by retrieving it from the viewer's advertisement cache.", "While the advertisement is being displayed, the regular programming is stored in a buffer which is thereafter retrieved and played in a time-shifted manner and after the advertisement is played.", "[0030] Such embodiment may be used in demographic segments that are relatively more price sensitive and are willing to endure more frequent commercial breaks in order to reduce their monthly subscription rates.", "The advertisement frequency is determined using the information stored in the handset related to subscription rates.", "The subscriber may choose to watch certain programs and channels without advertising by paying an additional amount over a subscription that would normally have the advertisement.", "[0031] Some embodiments of the present invention may credit the user for watching certain advertisement and to reduce the occurrence of future advertisements as a consequence.", "For example, a played long infomercial may allow one or more future programs to have no or a relatively reduced number of advertisements.", "A positive reaction by the subscriber to a viewed advertisement that leads to a call to advertiser or to a loading of an advertiser's web page may also accumulate credits.", "Accordingly, in such embodiments, enhanced exposure to advertisements provides credits toward viewing future commercial-free programs.", "[0032] The above embodiments of the present invention are illustrative and not limiting.", "Various alternatives and equivalents are possible.", "The invention is not limited by the type of digital device, mobile, etc.", "used for targeted advertisement.", "The invention is not limited by the rate used to transfer the data.", "Other additions, subtractions or modifications are obvious in view of the present disclosure and are intended to fall within the scope of the appended claims." ]
TECHNICAL FIELD [0001] The present disclosure relates generally to digital content distribution, and more specifically to computerized personalization of content delivered via a digital medium. BACKGROUND [0002] Presently, users of paid television services do not have the optimal television viewing experience in large part due to a sheer number of channels that are preconfigured into fixed packages by television service providers or broadcasters. This minimizes usage and results in dissatisfaction because the users are forced to pay for and search for content among channels in which they have no interest. While a la carte channel options exist, broadcasters want the opportunity to sell content in a single package rather than have users purchase a la carte in order to increase revenue. A similar problem also arises in other industries in connection with online purchasing decisions. Therefore, a method is needed that would bridge the needs of the content providers, broadcasters and consumers in connection with online purchasing. SUMMARY [0003] Embodiments of the present disclosure provide a system and method for digital content subscription personalization. As described in further detail below, embodiments of the present disclosure provide both new and existing customers incentives and ability to customize their TV channel selections within the context of a specific content package that is pre-defined. [0004] In one embodiment, a method for computerized personalization of digital content purchasing is disclosed. The method includes receiving, by a content subscription server, at least one indicator of content item deselection from a predetermined content subscription package having a plurality of digital content items. The method further includes determining, by the content subscription server, a subscription state for a user based on removing digital content corresponding to the at least one indicator of content item deselection from the predetermined content subscription package, as well as determining, by the content subscription server, an incentive balance for the user based on the at least one indicator of content item deselection. The method additionally includes reducing, by the content subscription server, a content acquisition price for the user based on the incentive balance. [0005] In another embodiment, a content subscription server is disclosed. The server includes a processor and memory. The memory includes computer readable instructions executed by the processor that cause the processor to (a) receive at least one indicator of content item deselection from a predetermined content subscription package having a plurality of digital content items, (b) determine a subscription state for a user based on removing digital content corresponding to the at least one indicator of content item deselection from the predetermined content subscription package, (c) determine an incentive balance for the user based on the at least one indicator of content item deselection, and (d) reduce a content acquisition price for the user based on the incentive balance. [0006] In yet another embodiment, a method for personalization of packaged options is disclosed. The method includes receiving, via an option processing server, at least one indicator of option deselection from an option package having a plurality of predetermined option items, and determining, via the option processing server, an option selection state for a user based on the at least one indicator of option deselection from the option package. The method further includes determining, via the option processing server, an incentive balance for the user based on the at least one indicator of option deselection, and reducing, via the option processing server, an item acquisition price for the user based on the incentive balance. BRIEF DESCRIPTION OF THE DRAWINGS [0007] The present disclosure can be better understood by referring to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure. In the figures, reference numerals designate corresponding parts throughout the different views. [0008] FIG. 1 is a diagram illustrating a digital content distribution system in accordance with an embodiment of the present disclosure; [0009] FIG. 2 is a flow chart illustrating an embodiment of a method for computerized personalization of digital content subscription via the system of FIG. 1 ; [0010] FIG. 3 is a flow chart illustrating an embodiment of personalization aspects of a user interface of an application running on a digital content player device of FIG. 1 ; and [0011] FIGS. 4-10 are diagrams illustrating an embodiment of a user interface of an application executed by the digital content player device of FIG. 1 . DETAILED DESCRIPTION [0012] The present disclosure is herein described in detail with reference to embodiments illustrated in the drawings, which form a part hereof. Other embodiments may be used and/or other changes may be made without departing from the spirit or scope of the present disclosure. The illustrative embodiments described in the detailed description are not meant to be limiting of the subject matter presented herein. [0013] Reference will now be made to the exemplary embodiments illustrated in the drawings, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Alterations and further modifications of the inventive features illustrated herein, and additional applications of the principles of the inventions as illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the present disclosure. [0014] Referring to FIG. 1 , a digital content distribution system 100 for providing content subscription personalization incentives is shown. The digital content distribution system 100 of the present disclosure administers user subscriptions and billing by providing content personalization incentives to customize channel selections within predefined subscription packages. In one embodiment, the personalization incentives include points and corresponding subscription discounts that are awarded for reducing the number of channels that comprise a given predefined subscription package. This ensures that the remaining channels are properly aligned with user interests and maximizes the viewing time for each of the remaining channels in the package. [0015] The system 100 includes a plurality of content server systems 102 - 106 , as well as a user digital medium system 108 , which is connected to content server systems 102 - 106 via a network, such as the Internet, a wide are network (WAN), a local area network (LAN), and/or a mobile telephone network, or the like. In particular, the system 100 includes a content processing server system 106 that receives digital content, such as live television (TV) streams, from a content provider through a content delivery network (CDN) via communication equipment 110 . Although the illustrated embodiment is described with respect to TV content streaming, those skilled in the art will realize that the present disclosure is not limited to particular content types and may be applicable to, for example, audio content delivery, photo content delivery, or any other content amenable to personalization in view of incentives applied in a digital medium, including additional examples, such as car option package personalization, described below. In various embodiments, the communication equipment 110 includes satellite and/or microwave receiver or transceiver and antenna equipment for receiving the live TV stream. Alternatively or in addition, the live TV content may be received via a wireline connection, such as a dedicated land-line or fiber. Additional embodiments of content delivery media include coax, TP-cable, xDSL, radio link or DTH, as well as hybrid solutions, such as IP over PDH or Ethernet-based FTTB. The content processing server system 106 is largely agnostic to the received content signal's encoding format, transport layer, and physical delivery media. In embodiments, the content signal, when it is received, may have been encoded in SDI, MPEG-2 4:2:2, MPEG-2 4:2:0, MPEG-4 4:4:4, MPEG-4 4:2:2, MPEG-4 4:2:0, JPEG-2000 or SMPTE VC-1 format. Embodiments of the transport layer include SDI/ASI, IP, DVB-S2, PDH, SDH or NGSDH (DTM), among others. In one embodiment, the content processing server system 106 receives a HD-SDI encoded content signal over IP on redundant fiber. [0016] The received content signal is then transcoded by the transcoding server 112 into a digital format that is compatible with the system 100 , including the format that is compatible with the access control, digital rights management (DRM), and subscription management server systems and their associated services and that may be replayed via the digital content player application 114 and associated digital content player device 115 . In one embodiment, the content player application 114 running on the player device 115 issues content requests, performs streaming, and communicates user selections and commands to the content subscription server system 102 , content access server system 104 , and content processing server system 106 via HTTP. In various embodiments, the player device 115 may be a mobile phone, a tablet, a computer, a dedicated audio/video digital content streamer, including a smart TV device, or a device running an internet browser. The content player application 114 may be a stand-alone mobile or desktop application, as well as a browser based application, such as a plug-in. [0017] The encryption server 116 encrypts the transcoded digital content for storage in the media storage database 118 . In an embodiment, the encryption is applied subsequent to processing by the DRM service 120 executed by the content access server system 104 , where the DRM service 120 wraps the segments in a DRM protective cover in accordance with the content license specifications stored in the license server 128 . [0018] The content access server system 104 is responsible for authenticating and authorizing access when a user 122 initiates a request to view particular content (e.g., a live or pre-recorded TV stream) via a content viewer application 114 executing on the playback device 115 . In addition to the DRM service 120 , the content access server system 104 executes an access service 124 , which ensures that the requested content is generally available (e.g., that it has not expired) and that it is available for a particular user 122 based on the user's subscription, which may be modified in view of the incentives associated with package personalization channel selections and/or de-selections, as discussed in further detail below. The access service 124 also accesses an IP geolocation (GeoIP) database 126 in order to check geographic restrictions, such as restrictions affecting content availability for users associated with a specific geographic region (e.g., based on a location in the subscription profile or location determined based on an IP address associated with the content request). The access service 124 also accesses parental control settings associated with a user's profile, which in one embodiment is stored in a separate database, as part of issuing an authorization approval for the requested content. In an embodiment, a user's profile may include parental control settings on channel-wide, program-specific, ratings-specific, or topic-specific level. When the access service 124 issues an authorization to access the requested content, the DRM service 120 exchanges encryption keys with the content player application 114 running on the player device 115 for the user to decrypt the requested content. The requested content is then fetched, in an encrypted form, from the media storage database 118 . [0019] In accordance with the present disclosure, the content subscription server system 102 administers user subscriptions and billing by providing content personalization incentives to customize channel selections within predefined subscription packages. In the illustrated embodiment, the personalization incentives include points that are awarded for reducing the number of channels that comprise a given predefined subscription package. This ensures that the remaining channels are properly aligned with user interests and maximizes the likelihood that the user will increase viewing time for each of the remaining channels in the package. The increase in average viewing time per channel, in turn, increases the value of advertising content and makes it better targeted to the user's interests. In this embodiment, the user 122 accumulates points by de-selecting one or more channels from the package. The points balance is then converted to a monetary discount which is applied to the subscription bill. Alternatively, the user 122 may choose to accumulate some or all of the point incentives for later use or apply some or all of the point incentives toward adding one or more channel from another (e.g., higher priced) predefined subscription package. While the illustrated embodiment involves generation of incentive points for de-selecting channels within a pre-defined lineup or package, the present disclosure is not limited to this method of generating content personalization incentives. In various non-limiting examples, content personalization points (and corresponding discount balances) may be awarded for other content personalization activities. Such content personalization activities may include the user 122 selecting via the application 114 to receive notifications when a certain show is about to become available for viewing, sharing the user's watch list and/or electronic program guide (EPG) channel order with other users of the system 100 and/or via social media, entering social media account information into the application 114 , creating family member accounts, signing up for paid subscription after a free trial period, watching or otherwise consuming a predetermined amount of TV or other digital content, as well as ad hoc points awarded by content providers for watching or otherwise consuming specific TV or other digital content, among others. [0020] In the illustrated embodiment, the content subscription server system 102 executes a plurality of services for communicating subscription package selections and personalization settings, as well as payment information, to and from the user application 114 . In particular, the first superscription service 130 receives, for example via HTTP messaging, channel deselection indicators entered into the application 114 , as well as other content personalization activity settings described above. Similarly, the second superscription service 132 receives channel plan indicators corresponding to the deselected channel indicators received via the first superscription service 130 . The channel deselection indicators and the corresponding channel plan indicators are stored in the event log database 134 . The subscription state snapshot service 136 reads the event log database 134 to determine the user's subscription status by removing the deselected channel plan indicators from the list of channel indicators associated with the user's channel package(s) and updates the access service 124 . To provide the content personalization incentives, the incentives service 138 reads a list of deselected channels from the subscription state snapshot service 136 and calculates a discount in the user's subscription price based on the number of accumulated personalization points. In an embodiment, the personalization points awarded for deselecting a given channel vary based on the package from which the channel was deselected (e.g., high-cost channel deselection results in a higher point balance award as compared to low-cost or free channel deselection). The billing service 140 reads the discount calculated by the incentive service 138 , applies it to the user's current subscription read from the subscription state snapshot service 136 . Additionally, the billing service 140 processes subscription payments submitted by the user 122 via the content player application 114 executing on the player device 115 . [0021] Referring to FIG. 2 , an embodiment of a method for presenting the user with content personalization incentives via a user interface of the application 114 , depicted in FIGS. 3-10 , is shown. In step 200 , the digital content distribution system 100 presents an application user interface for selecting a TV package subscription or initiating a free trial via a digital content player device 115 . If, in step 202 , the user had previously selected a “My TV Plan” by personalizing a set of channels from one or more preset subscription packages, then, in step 204 , the “personalize” button 400 is displayed in the electronic program guide (EPG) pages 402 , 1000 ( FIGS. 4, 10 ). In an embodiment, the user selects what is referred to as the “My TV Plan” by deselecting one or more TV channels from a preset channel package line up presented via a subscription screen 700 a, 700 b, 700 c that spans FIGS. 7-9 . In step 206 , if the user activates the “Personalize” button 400 ( FIGS. 3-4 ), he is then presented with the content personalization screen 500 depicted in FIGS. 5-6 . The content personalization screen 500 allows the user to personalize the content viewing experience by customizing the sort order of the TV channels in the EPG via the “Arrange” button 502 . In step 208 , when the user selects the “Arrange” button 502 , the user is able to re-arrange the sort order of the channels appearing on the EPG, for example either by dragging a given channel icon to a desired position or by selecting the up and down sort buttons 506 - 510 , as shown in FIG. 6 . In step 210 , the content subscription server system 102 receives user input of EPG channel sort order. [0022] Additionally, the user is incentivized to further personalize his subscription by customizing the channel selections via the “Choose Channels” button 504 . To this end, in steps 212 - 214 , the content subscription server system 102 receives user input of channel de-selections when the user 122 deselects one or more channels from the preset channel packages presented via the subscription screen 700 a, 700 b, 700 c that spans FIGS. 7-9 . As shown in further detail in FIGS. 7-9 , the subscription screen displays a plurality of preset channel packages, such as the “Magic” package 702 , the “Master” package 800 , and the “Free” package 900 (e.g., streamed public television TV channels). A selection box disposed next to each of the channel names and package names allows the user to select or deselect a given package or channel name. For example, as shown in the embodiment of FIG. 7 , the user deselected a majority of the channels within the preset “Magic” package by deselecting the corresponding channel selection boxes, while selecting all of the channels in the “Master” package 800 and “Free” package 900 via package selection boxes 802 , 902 . In an embodiment, deselection of a channel within a given TV package results in an award of a point balance to the user. In the illustrated embodiment, the point balance award may be higher for paid channels, such as the “Magic” package 702 , with respect to the free or lower subscription based channels, such as the “Master package 800 and “Free” package 900 . The content subscription server system 102 converts the user's personalization point award balance to a subscription discount when the user selects a paid subscription. In one embodiment, shown in FIG. 3 , the user's personalization points balance and/or associated discounted price 300 is displayed and updated in real time as the user deselects channels from a given TV package. In another embodiment, the personalization point balance and/or associated subscription discount is displayed when the user is ready to purchase the personalized subscription, as shown in FIG. 9 (e.g., “personalization incentive” 904 ). [0023] Referring again to FIG. 2 , in steps 216 - 218 , if the user is not yet ready to pay, the personalized “My TV” plan selected by the user is activated or updated as part of a free trial (if available in accordance with permissions set by the access service 124 ). Otherwise, if the user is ready to pay for the personalized subscription, in steps 220 - 222 , the content subscription server system 102 determines the user's personalization points balance in accordance with channel deselections made by the user and adjusts the package price in accordance with the corresponding personalization incentive discount. In another embodiment, user's customized EPG channel sorting selections, as well as any of the additional personalization options discussed above in connection with FIG. 1 , also result in personalization points and corresponding subscription discounts determined by the content subscription server system 102 . In steps 224 - 226 , the content subscription server system 102 processes user payment and activates a new or updated personalized “My TV Plan” paid subscription. [0024] Referring again to step 202 of FIG. 2 , in the event that the user has not previously personalized his subscription by selecting the “My TV” plan, the user is presented with an opportunity to do so, in step 228 , via the subscription screen 700 a, 700 b, 700 c ( FIGS. 7-9 ). If, in step 230 , the user elects to personalize his channel subscription, the flow continues to steps 208 - 226 as described above. Otherwise, when the user is ready to pay, he elects one or more preset TV channel packages 702 , 800 , 900 without making the deselections of any channels—and hence personalization incentives are not applied when the content subscription server system 102 processes payment and activates the preset plan paid subscription, steps 232 - 236 . In the event the user is not yet ready to pay, the content subscription server system 102 activates or updates the free trial subscription to the preset plan(s) selected by the user, step 238 . As those of skill in the art will realize, some or all of the functionality executed by content subscription server system 102 may be shared with or instead performed by the user's content player device 114 (e.g., when programmed into application code or loaded into device memory). [0025] While the foregoing description discussed digital TV streaming channel subscription personalization embodiments, those of skill in the art will realize that the systems and methods described herein are also applicable in a plurality of other contexts. Among various additional examples, for instance, is using preset package personalization incentives in the context of automobile orders communicated via a digital medium (e.g., online) where a consumer receives reward points for deselecting one or more features of a predetermined options package. This optimizes manufacturing efficiency by decreasing the time and expense needed to manufacture unpopular options. Additional examples of various contexts in which the present disclosure is applicable include music and movies industries where pre-packaged content is offered to the user. [0026] While various aspects and embodiments have been disclosed, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims. [0027] The foregoing method descriptions and the process flow diagrams are provided merely as illustrative examples and are not intended to require or imply that the steps of the various embodiments must be performed in the order presented. As will be appreciated by one of skill in the art the steps in the foregoing embodiments may be performed in any order. Words such as “then,” “next,” etc. are not intended to limit the order of the steps; these words are simply used to guide the reader through the description of the methods. Although process flow diagrams may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination may correspond to a return of the function to the calling function or the main function. [0028] The various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed here may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. [0029] Embodiments implemented in computer software may be implemented in software, firmware, middleware, microcode, hardware description languages, or any combination thereof. A code segment or machine-executable instructions may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc. [0030] The actual software code or specialized control hardware used to implement these systems and methods is not limiting of the invention. Thus, the operation and behavior of the systems and methods were described without reference to the specific software code being understood that software and control hardware can be designed to implement the systems and methods based on the description here. [0031] When implemented in software, the functions may be stored as one or more instructions or code on a non-transitory computer-readable or processor-readable storage medium. The steps of a method or algorithm disclosed here may be embodied in a processor-executable software module which may reside on a computer-readable or processor-readable storage medium. A non-transitory computer-readable or processor-readable media includes both computer storage media and tangible storage media that facilitate transfer of a computer program from one place to another. A non-transitory processor-readable storage media may be any available media that may be accessed by a computer. By way of example, and not limitation, such non-transitory processor-readable media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other tangible storage medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer or processor. Disk and disc, as used here, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and/or instructions on a non-transitory processor-readable medium and/or computer-readable medium, which may be incorporated into a computer program product. [0032] The preceding description of the disclosed embodiments is provided to enable any person skilled in the art to make and use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined here may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown here but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed here.
Systems and methods for incentivizing computerized personalization of content delivered via a digital medium are disclosed. An embodiment of the method includes receiving, via a content subscription server, at least one indicator of content item deselection from a predetermined content subscription package having a plurality of digital content items. The method further includes determining, via the content subscription server, a subscription state for a user based on removing digital content corresponding to the at least one indicator of content item deselection from the predetermined content subscription package, as well as determining, via the content subscription server, an incentive balance for the user based on the at least one indicator of content item deselection. The method additionally includes reducing, via the content subscription server, a content acquisition price for the user based on the incentive balance.
Briefly describe the main invention outlined in the provided context.
[ "TECHNICAL FIELD [0001] The present disclosure relates generally to digital content distribution, and more specifically to computerized personalization of content delivered via a digital medium.", "BACKGROUND [0002] Presently, users of paid television services do not have the optimal television viewing experience in large part due to a sheer number of channels that are preconfigured into fixed packages by television service providers or broadcasters.", "This minimizes usage and results in dissatisfaction because the users are forced to pay for and search for content among channels in which they have no interest.", "While a la carte channel options exist, broadcasters want the opportunity to sell content in a single package rather than have users purchase a la carte in order to increase revenue.", "A similar problem also arises in other industries in connection with online purchasing decisions.", "Therefore, a method is needed that would bridge the needs of the content providers, broadcasters and consumers in connection with online purchasing.", "SUMMARY [0003] Embodiments of the present disclosure provide a system and method for digital content subscription personalization.", "As described in further detail below, embodiments of the present disclosure provide both new and existing customers incentives and ability to customize their TV channel selections within the context of a specific content package that is pre-defined.", "[0004] In one embodiment, a method for computerized personalization of digital content purchasing is disclosed.", "The method includes receiving, by a content subscription server, at least one indicator of content item deselection from a predetermined content subscription package having a plurality of digital content items.", "The method further includes determining, by the content subscription server, a subscription state for a user based on removing digital content corresponding to the at least one indicator of content item deselection from the predetermined content subscription package, as well as determining, by the content subscription server, an incentive balance for the user based on the at least one indicator of content item deselection.", "The method additionally includes reducing, by the content subscription server, a content acquisition price for the user based on the incentive balance.", "[0005] In another embodiment, a content subscription server is disclosed.", "The server includes a processor and memory.", "The memory includes computer readable instructions executed by the processor that cause the processor to (a) receive at least one indicator of content item deselection from a predetermined content subscription package having a plurality of digital content items, (b) determine a subscription state for a user based on removing digital content corresponding to the at least one indicator of content item deselection from the predetermined content subscription package, (c) determine an incentive balance for the user based on the at least one indicator of content item deselection, and (d) reduce a content acquisition price for the user based on the incentive balance.", "[0006] In yet another embodiment, a method for personalization of packaged options is disclosed.", "The method includes receiving, via an option processing server, at least one indicator of option deselection from an option package having a plurality of predetermined option items, and determining, via the option processing server, an option selection state for a user based on the at least one indicator of option deselection from the option package.", "The method further includes determining, via the option processing server, an incentive balance for the user based on the at least one indicator of option deselection, and reducing, via the option processing server, an item acquisition price for the user based on the incentive balance.", "BRIEF DESCRIPTION OF THE DRAWINGS [0007] The present disclosure can be better understood by referring to the following figures.", "The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure.", "In the figures, reference numerals designate corresponding parts throughout the different views.", "[0008] FIG. 1 is a diagram illustrating a digital content distribution system in accordance with an embodiment of the present disclosure;", "[0009] FIG. 2 is a flow chart illustrating an embodiment of a method for computerized personalization of digital content subscription via the system of FIG. 1 ;", "[0010] FIG. 3 is a flow chart illustrating an embodiment of personalization aspects of a user interface of an application running on a digital content player device of FIG. 1 ;", "and [0011] FIGS. 4-10 are diagrams illustrating an embodiment of a user interface of an application executed by the digital content player device of FIG. 1 .", "DETAILED DESCRIPTION [0012] The present disclosure is herein described in detail with reference to embodiments illustrated in the drawings, which form a part hereof.", "Other embodiments may be used and/or other changes may be made without departing from the spirit or scope of the present disclosure.", "The illustrative embodiments described in the detailed description are not meant to be limiting of the subject matter presented herein.", "[0013] Reference will now be made to the exemplary embodiments illustrated in the drawings, and specific language will be used herein to describe the same.", "It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.", "Alterations and further modifications of the inventive features illustrated herein, and additional applications of the principles of the inventions as illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the present disclosure.", "[0014] Referring to FIG. 1 , a digital content distribution system 100 for providing content subscription personalization incentives is shown.", "The digital content distribution system 100 of the present disclosure administers user subscriptions and billing by providing content personalization incentives to customize channel selections within predefined subscription packages.", "In one embodiment, the personalization incentives include points and corresponding subscription discounts that are awarded for reducing the number of channels that comprise a given predefined subscription package.", "This ensures that the remaining channels are properly aligned with user interests and maximizes the viewing time for each of the remaining channels in the package.", "[0015] The system 100 includes a plurality of content server systems 102 - 106 , as well as a user digital medium system 108 , which is connected to content server systems 102 - 106 via a network, such as the Internet, a wide are network (WAN), a local area network (LAN), and/or a mobile telephone network, or the like.", "In particular, the system 100 includes a content processing server system 106 that receives digital content, such as live television (TV) streams, from a content provider through a content delivery network (CDN) via communication equipment 110 .", "Although the illustrated embodiment is described with respect to TV content streaming, those skilled in the art will realize that the present disclosure is not limited to particular content types and may be applicable to, for example, audio content delivery, photo content delivery, or any other content amenable to personalization in view of incentives applied in a digital medium, including additional examples, such as car option package personalization, described below.", "In various embodiments, the communication equipment 110 includes satellite and/or microwave receiver or transceiver and antenna equipment for receiving the live TV stream.", "Alternatively or in addition, the live TV content may be received via a wireline connection, such as a dedicated land-line or fiber.", "Additional embodiments of content delivery media include coax, TP-cable, xDSL, radio link or DTH, as well as hybrid solutions, such as IP over PDH or Ethernet-based FTTB.", "The content processing server system 106 is largely agnostic to the received content signal's encoding format, transport layer, and physical delivery media.", "In embodiments, the content signal, when it is received, may have been encoded in SDI, MPEG-2 4:2:2, MPEG-2 4:2:0, MPEG-4 4:4:4, MPEG-4 4:2:2, MPEG-4 4:2:0, JPEG-2000 or SMPTE VC-1 format.", "Embodiments of the transport layer include SDI/ASI, IP, DVB-S2, PDH, SDH or NGSDH (DTM), among others.", "In one embodiment, the content processing server system 106 receives a HD-SDI encoded content signal over IP on redundant fiber.", "[0016] The received content signal is then transcoded by the transcoding server 112 into a digital format that is compatible with the system 100 , including the format that is compatible with the access control, digital rights management (DRM), and subscription management server systems and their associated services and that may be replayed via the digital content player application 114 and associated digital content player device 115 .", "In one embodiment, the content player application 114 running on the player device 115 issues content requests, performs streaming, and communicates user selections and commands to the content subscription server system 102 , content access server system 104 , and content processing server system 106 via HTTP.", "In various embodiments, the player device 115 may be a mobile phone, a tablet, a computer, a dedicated audio/video digital content streamer, including a smart TV device, or a device running an internet browser.", "The content player application 114 may be a stand-alone mobile or desktop application, as well as a browser based application, such as a plug-in.", "[0017] The encryption server 116 encrypts the transcoded digital content for storage in the media storage database 118 .", "In an embodiment, the encryption is applied subsequent to processing by the DRM service 120 executed by the content access server system 104 , where the DRM service 120 wraps the segments in a DRM protective cover in accordance with the content license specifications stored in the license server 128 .", "[0018] The content access server system 104 is responsible for authenticating and authorizing access when a user 122 initiates a request to view particular content (e.g., a live or pre-recorded TV stream) via a content viewer application 114 executing on the playback device 115 .", "In addition to the DRM service 120 , the content access server system 104 executes an access service 124 , which ensures that the requested content is generally available (e.g., that it has not expired) and that it is available for a particular user 122 based on the user's subscription, which may be modified in view of the incentives associated with package personalization channel selections and/or de-selections, as discussed in further detail below.", "The access service 124 also accesses an IP geolocation (GeoIP) database 126 in order to check geographic restrictions, such as restrictions affecting content availability for users associated with a specific geographic region (e.g., based on a location in the subscription profile or location determined based on an IP address associated with the content request).", "The access service 124 also accesses parental control settings associated with a user's profile, which in one embodiment is stored in a separate database, as part of issuing an authorization approval for the requested content.", "In an embodiment, a user's profile may include parental control settings on channel-wide, program-specific, ratings-specific, or topic-specific level.", "When the access service 124 issues an authorization to access the requested content, the DRM service 120 exchanges encryption keys with the content player application 114 running on the player device 115 for the user to decrypt the requested content.", "The requested content is then fetched, in an encrypted form, from the media storage database 118 .", "[0019] In accordance with the present disclosure, the content subscription server system 102 administers user subscriptions and billing by providing content personalization incentives to customize channel selections within predefined subscription packages.", "In the illustrated embodiment, the personalization incentives include points that are awarded for reducing the number of channels that comprise a given predefined subscription package.", "This ensures that the remaining channels are properly aligned with user interests and maximizes the likelihood that the user will increase viewing time for each of the remaining channels in the package.", "The increase in average viewing time per channel, in turn, increases the value of advertising content and makes it better targeted to the user's interests.", "In this embodiment, the user 122 accumulates points by de-selecting one or more channels from the package.", "The points balance is then converted to a monetary discount which is applied to the subscription bill.", "Alternatively, the user 122 may choose to accumulate some or all of the point incentives for later use or apply some or all of the point incentives toward adding one or more channel from another (e.g., higher priced) predefined subscription package.", "While the illustrated embodiment involves generation of incentive points for de-selecting channels within a pre-defined lineup or package, the present disclosure is not limited to this method of generating content personalization incentives.", "In various non-limiting examples, content personalization points (and corresponding discount balances) may be awarded for other content personalization activities.", "Such content personalization activities may include the user 122 selecting via the application 114 to receive notifications when a certain show is about to become available for viewing, sharing the user's watch list and/or electronic program guide (EPG) channel order with other users of the system 100 and/or via social media, entering social media account information into the application 114 , creating family member accounts, signing up for paid subscription after a free trial period, watching or otherwise consuming a predetermined amount of TV or other digital content, as well as ad hoc points awarded by content providers for watching or otherwise consuming specific TV or other digital content, among others.", "[0020] In the illustrated embodiment, the content subscription server system 102 executes a plurality of services for communicating subscription package selections and personalization settings, as well as payment information, to and from the user application 114 .", "In particular, the first superscription service 130 receives, for example via HTTP messaging, channel deselection indicators entered into the application 114 , as well as other content personalization activity settings described above.", "Similarly, the second superscription service 132 receives channel plan indicators corresponding to the deselected channel indicators received via the first superscription service 130 .", "The channel deselection indicators and the corresponding channel plan indicators are stored in the event log database 134 .", "The subscription state snapshot service 136 reads the event log database 134 to determine the user's subscription status by removing the deselected channel plan indicators from the list of channel indicators associated with the user's channel package(s) and updates the access service 124 .", "To provide the content personalization incentives, the incentives service 138 reads a list of deselected channels from the subscription state snapshot service 136 and calculates a discount in the user's subscription price based on the number of accumulated personalization points.", "In an embodiment, the personalization points awarded for deselecting a given channel vary based on the package from which the channel was deselected (e.g., high-cost channel deselection results in a higher point balance award as compared to low-cost or free channel deselection).", "The billing service 140 reads the discount calculated by the incentive service 138 , applies it to the user's current subscription read from the subscription state snapshot service 136 .", "Additionally, the billing service 140 processes subscription payments submitted by the user 122 via the content player application 114 executing on the player device 115 .", "[0021] Referring to FIG. 2 , an embodiment of a method for presenting the user with content personalization incentives via a user interface of the application 114 , depicted in FIGS. 3-10 , is shown.", "In step 200 , the digital content distribution system 100 presents an application user interface for selecting a TV package subscription or initiating a free trial via a digital content player device 115 .", "If, in step 202 , the user had previously selected a “My TV Plan”", "by personalizing a set of channels from one or more preset subscription packages, then, in step 204 , the “personalize”", "button 400 is displayed in the electronic program guide (EPG) pages 402 , 1000 ( FIGS. 4, 10 ).", "In an embodiment, the user selects what is referred to as the “My TV Plan”", "by deselecting one or more TV channels from a preset channel package line up presented via a subscription screen 700 a, 700 b, 700 c that spans FIGS. 7-9 .", "In step 206 , if the user activates the “Personalize”", "button 400 ( FIGS. 3-4 ), he is then presented with the content personalization screen 500 depicted in FIGS. 5-6 .", "The content personalization screen 500 allows the user to personalize the content viewing experience by customizing the sort order of the TV channels in the EPG via the “Arrange”", "button 502 .", "In step 208 , when the user selects the “Arrange”", "button 502 , the user is able to re-arrange the sort order of the channels appearing on the EPG, for example either by dragging a given channel icon to a desired position or by selecting the up and down sort buttons 506 - 510 , as shown in FIG. 6 .", "In step 210 , the content subscription server system 102 receives user input of EPG channel sort order.", "[0022] Additionally, the user is incentivized to further personalize his subscription by customizing the channel selections via the “Choose Channels”", "button 504 .", "To this end, in steps 212 - 214 , the content subscription server system 102 receives user input of channel de-selections when the user 122 deselects one or more channels from the preset channel packages presented via the subscription screen 700 a, 700 b, 700 c that spans FIGS. 7-9 .", "As shown in further detail in FIGS. 7-9 , the subscription screen displays a plurality of preset channel packages, such as the “Magic”", "package 702 , the “Master”", "package 800 , and the “Free”", "package 900 (e.g., streamed public television TV channels).", "A selection box disposed next to each of the channel names and package names allows the user to select or deselect a given package or channel name.", "For example, as shown in the embodiment of FIG. 7 , the user deselected a majority of the channels within the preset “Magic”", "package by deselecting the corresponding channel selection boxes, while selecting all of the channels in the “Master”", "package 800 and “Free”", "package 900 via package selection boxes 802 , 902 .", "In an embodiment, deselection of a channel within a given TV package results in an award of a point balance to the user.", "In the illustrated embodiment, the point balance award may be higher for paid channels, such as the “Magic”", "package 702 , with respect to the free or lower subscription based channels, such as the “Master package 800 and “Free”", "package 900 .", "The content subscription server system 102 converts the user's personalization point award balance to a subscription discount when the user selects a paid subscription.", "In one embodiment, shown in FIG. 3 , the user's personalization points balance and/or associated discounted price 300 is displayed and updated in real time as the user deselects channels from a given TV package.", "In another embodiment, the personalization point balance and/or associated subscription discount is displayed when the user is ready to purchase the personalized subscription, as shown in FIG. 9 (e.g., “personalization incentive”", "904 ).", "[0023] Referring again to FIG. 2 , in steps 216 - 218 , if the user is not yet ready to pay, the personalized “My TV”", "plan selected by the user is activated or updated as part of a free trial (if available in accordance with permissions set by the access service 124 ).", "Otherwise, if the user is ready to pay for the personalized subscription, in steps 220 - 222 , the content subscription server system 102 determines the user's personalization points balance in accordance with channel deselections made by the user and adjusts the package price in accordance with the corresponding personalization incentive discount.", "In another embodiment, user's customized EPG channel sorting selections, as well as any of the additional personalization options discussed above in connection with FIG. 1 , also result in personalization points and corresponding subscription discounts determined by the content subscription server system 102 .", "In steps 224 - 226 , the content subscription server system 102 processes user payment and activates a new or updated personalized “My TV Plan”", "paid subscription.", "[0024] Referring again to step 202 of FIG. 2 , in the event that the user has not previously personalized his subscription by selecting the “My TV”", "plan, the user is presented with an opportunity to do so, in step 228 , via the subscription screen 700 a, 700 b, 700 c ( FIGS. 7-9 ).", "If, in step 230 , the user elects to personalize his channel subscription, the flow continues to steps 208 - 226 as described above.", "Otherwise, when the user is ready to pay, he elects one or more preset TV channel packages 702 , 800 , 900 without making the deselections of any channels—and hence personalization incentives are not applied when the content subscription server system 102 processes payment and activates the preset plan paid subscription, steps 232 - 236 .", "In the event the user is not yet ready to pay, the content subscription server system 102 activates or updates the free trial subscription to the preset plan(s) selected by the user, step 238 .", "As those of skill in the art will realize, some or all of the functionality executed by content subscription server system 102 may be shared with or instead performed by the user's content player device 114 (e.g., when programmed into application code or loaded into device memory).", "[0025] While the foregoing description discussed digital TV streaming channel subscription personalization embodiments, those of skill in the art will realize that the systems and methods described herein are also applicable in a plurality of other contexts.", "Among various additional examples, for instance, is using preset package personalization incentives in the context of automobile orders communicated via a digital medium (e.g., online) where a consumer receives reward points for deselecting one or more features of a predetermined options package.", "This optimizes manufacturing efficiency by decreasing the time and expense needed to manufacture unpopular options.", "Additional examples of various contexts in which the present disclosure is applicable include music and movies industries where pre-packaged content is offered to the user.", "[0026] While various aspects and embodiments have been disclosed, other aspects and embodiments are contemplated.", "The various aspects and embodiments disclosed are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.", "[0027] The foregoing method descriptions and the process flow diagrams are provided merely as illustrative examples and are not intended to require or imply that the steps of the various embodiments must be performed in the order presented.", "As will be appreciated by one of skill in the art the steps in the foregoing embodiments may be performed in any order.", "Words such as “then,” “next,” etc.", "are not intended to limit the order of the steps;", "these words are simply used to guide the reader through the description of the methods.", "Although process flow diagrams may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently.", "In addition, the order of the operations may be re-arranged.", "A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc.", "When a process corresponds to a function, its termination may correspond to a return of the function to the calling function or the main function.", "[0028] The various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed here may be implemented as electronic hardware, computer software, or combinations of both.", "To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality.", "Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.", "Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.", "[0029] Embodiments implemented in computer software may be implemented in software, firmware, middleware, microcode, hardware description languages, or any combination thereof.", "A code segment or machine-executable instructions may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements.", "A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents.", "Information, arguments, parameters, data, etc.", "may be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc.", "[0030] The actual software code or specialized control hardware used to implement these systems and methods is not limiting of the invention.", "Thus, the operation and behavior of the systems and methods were described without reference to the specific software code being understood that software and control hardware can be designed to implement the systems and methods based on the description here.", "[0031] When implemented in software, the functions may be stored as one or more instructions or code on a non-transitory computer-readable or processor-readable storage medium.", "The steps of a method or algorithm disclosed here may be embodied in a processor-executable software module which may reside on a computer-readable or processor-readable storage medium.", "A non-transitory computer-readable or processor-readable media includes both computer storage media and tangible storage media that facilitate transfer of a computer program from one place to another.", "A non-transitory processor-readable storage media may be any available media that may be accessed by a computer.", "By way of example, and not limitation, such non-transitory processor-readable media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other tangible storage medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer or processor.", "Disk and disc, as used here, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers.", "Combinations of the above should also be included within the scope of computer-readable media.", "Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and/or instructions on a non-transitory processor-readable medium and/or computer-readable medium, which may be incorporated into a computer program product.", "[0032] The preceding description of the disclosed embodiments is provided to enable any person skilled in the art to make and use the present invention.", "Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined here may be applied to other embodiments without departing from the spirit or scope of the invention.", "Thus, the present invention is not intended to be limited to the embodiments shown here but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed here." ]
CROSS REFERENCE TO RELATED APPLICATIONS This application is a Continuation-In-Part of co-pending Ser. No. 436,391 filed on Jan. 24, 1974, by the inventors herein. BACKGROUND OF THE INVENTION This invention generally relates to catamenial devices such as tampons and other insertable articles which are prepared from hydrophilic polymeric foam materials. As noted in the above-identified co-pending application, catamenial devices such as tampons have been prepared from a wide variety of synthetic and naturally occuring organic materials in the form of fibers and sponge-like materials, but have all suffered from various critical defects. Generally, a device such as a tampon which is to be inserted in an easily irritable area of the body cavity must possess a refined texture and flexibility, while, at the same time, possessing a significant absorptive capacity and the ability to rapidly and uniformly re-expand in contact with moisture such as occasioned by the menstrual flow. The latter property is required because the device must assume a reduced size to facilitate its insertion. Generally, prior art devices have lacked one or more of the above properties, as absorption is usually gained at the expense of size, and flexibility and texture are sacrificed to the ability to undergo re-expansion. In the context of the above discussion, Applicants sought to provide a device combining all of the favorable characteristics, and, accordingly, developed a catamenial device prepared from a hydrophilic, rapidly re-expandable polymeric foam which is compressed to less than 50 percent of its dry volume and then placed within a soluble, lubricious constraining means such as a capsule. The material most often comprising the capsule of this device is a gelatin compound, which was known to possess the requisite lubricity and solubility as well as non-toxicity to living tissue. Further experimentation conducted since the development of the above has uncovered a useful alternate material for the preparation of the constraining means which possesses all of the above properties and is easier and less expensive to employ. SUMMARY OF THE INVENTION In accordance with the present invention, a catamenial device is disclosed which comprises a hydrophilic, rapidly reexpandable polymeric foam segment which is compressed and placed within a constraining means for an extended period of time, wherein said constraining means comprises a water-soluble coating formed by a composition comprising citric acid and sodium bicarbonate. The coating composition may either be applied topically in solution to the surface of the segment, or the segment may be fully impregnated therewith. The composition of the present invention may, in an alternate embodiment, be employed as a release agent, by conducting a dry impregnation of the foam prior to shaping and constraint thereof, as disclosed in the copending parent application noted above. Catamenial devices prepared with the coating composition of the invention exhibit favorable storage stability in compression over extended periods of time, and, upon contact with moisture, re-expand rapidly to a volume significantly in excess of original dry volume, due to the effervescence of the composition. Tampons prepared in accordance herewith likewise unexpectedly perform a medicinal function, as the presence of the coating composition in the vaginal canal restores the slightly acidic pH necessary to the prevention of vaginitis during the menstrual period. Accordingly, it is a principal object of the present invention to provide a catamenial device comprising a hydrophilic polymeric foam held in a compression by a coating composition comprising citric acid and sodium bicarbonate. It is a further object of the present invention to provide a device as aforesaid which exhibits improved shelf stability under compression, yet is rapidly re-expandable in contact with moisture. It is yet a further object of the present invention to provide a device as aforesaid which renders medicinal assistance to the vaginal area during the menstrual flow. It is a still further object of the present invention to provide a method of impregnating a polymeric foam to render said foam more rapidly re-expandable in contact with moisture. Other objects and advantages will appear from a consideration of the description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow diagram outlining the preparation of the device of this invention with a full wet impregnation technique. FIG. 2 is a flow diagram outlining the dry impregnation of the foam with the coating composition employed in accordance with the invention. FIG. 3 is a perspective view of a tampon prepared in accordance with the technique of FIG. 1. DETAILED DESCRIPTION In accordance with the present invention, the foregoing objects and advantages are readily obtained. The present invention comprises a catamenial device such as a tampon which is prepared from a rapidly re-expandable hydrophilic polymeric foam segment which is placed in compression and maintained therein by a constraining means comprising a coating prepared from a composition comprising citric acid and sodium bicarbonate. The composition may be applied in solution as a surface coating, or the foam segment may be impregnated therewith. As a further alternative embodiment, the foam may be dry impregnated with particles of the composition prior to being cut into segments and placed in compression within a constraining means such as a capsule. The devices and their general preparation, to which the present invention pertains, are disclosed in our copending parent application Ser. No. 436,391, incorporated herein by reference. The foams disclosed therein comprise hydrophilic polyurethane foams or hydrophilic formaldehyde polyvinylalcohol foams. It is preferred, however, that the foam be hydrophilic polyurethane foam. A commercially available hydrophilic polyurethane foam is marketed under the tradename Acquell®and is available from the Scott Paper Company. This is a polyurethane foam produced by the reaction of a polyesterdiol and tolylene diisocyanate. The polyesterdiol also contains adipic acid and block copolymers of polyoxyethylene and polyoxypropylene. Another foam which may be used in accordance with this invention is prepared by, in a in a first step, forming a prepolymer by the reaction of polyethylene glycol and trimethylol propane in a mole ratio of about 2:0.125 to 2:2 respectively, followed by capping the reaction product at all hydroxy locations using tolylene diisocyanate consisting of about an 80/20 mixture of the 2,4 isomer to 2,6 isomer; and in a second step reacting 100 parts by weight of prepolymer with 30 parts by weight of water containing 5 parts by weight of a polyoxyalkylene non-ionic surfactant. A particular non-ionic surfactant which has been found useful is one commercially available under the tradename Pluronic L-64 from the Wyandotte Chemicals Corporation. Although the above comprise the preferred hydrophilic urethane foam materials, other useful hydrophilic urethane foams are produced by varying the above prepolymer to water ratio, as well as varying the water to surfactant ratio. Polymeric foams which are to be employed in the preparation of a tampon assembly should preferably possess a maximum density of about 2.5 lbs./ft. 3 , as difficulties arise in the compression and encapsulation of foams whose density exceeds this level. The general preparation of the constrained device comprises the compression of the foam followed by insertion in the compressed state into a constraining means such as a capsule. Compression of the foam is usually conducted to a reduction of at least about 50% of its original dry volume, and in a preferred embodiment which is useful in tampon manufacture, the foam may be compressed from about less than 25 to about less than 10%. Any conventional type of press or device may be used. This operation may also be in combination with that of placing the compressed foam into the constraining means. The constraining means employed therein comprise a pre-formed capsule structure which, in a preferred embodiment, is prepared from a water-soluble non-toxic material such as gelatin. The adhesive coating composition comprising the constraining means of the present invention is a mixture of sodium bicarbonate and citric acid employed in roughly equal amounts. It has been discovered that the above mixture serves as a binder when placed on a foam segment and dried, and additionally, when subsequently wetted, provides sufficient effervescence to serve as a blowing agent which enhances the re-expansion of the foam. Beyond the above advantages, the composition of this invention also possesses a medicinal utility, as it provides a slightly acidic environment which is particularly useful in the vaginal area during the menstrual flow, and prevents the occurrence of vaginitis, which generally resulting from a loss of beneficial bacteria and a change toward an environment of slightly alkaline pH. The restoration of a slightly acidic environment also prevents the undue accumulation of noxious odor and irritation which results from the enzymatic reduction of the uric acid, urea, amino acids and the like constituting the menstrual discharge, to ammonia and volatile amines. As stated above, the sodium bicarbonate-citric acid composition of the invention may roughly comprise equal amounts of each ingredient. Specifically, the amounts of each may vary within 10%, so that both citric acid and sodium bicarbonate may be present in amounts ranging from 40 to 60% by weight of the total composition. Preparation in the above range has been found to impart the combination of desirable characteristics enumerated earlier. The composition may be employed in the catamenial device in a number of ways; as a constraining means applied as a topical liquid coating which dries to form an adhesive outer coat, or by thorough wet impregnation to reside throughout the device. If topical or surface application is employed, the foam segment should first be coated with the composition, after which it may be constrained to the desired volume. When the composition is to be employed in liquid form, it should be dispersed in water in a ratio thereto ranging from approximately 1:1 to 5:1 water to composition. When the composition is to be employed strictly as a topical adhesive, the preferred ratio comprises 1:1, as a highly viscous solution results which rapidly fixes the surface of the compressed foam in position. If full impregnation is desired, however, a more dilute solution is preferred to enable the composition to completely and uniformly penetrate the entire segment. Referring now to FIG. 1, a flow diagram set out the steps for full wet impregnation of the foam segment. The foam is first prepared to the shape of the final article, which, as illustrated herein, is a tampon. The foam will be cut to dimensions of about 1 × 1 × 2 inches which correspond to the size of a tampon device. The resulting foam segment is impregnated with a solution of the citric acid-bicarbonate composition, which is preferably employed at a 20 percent concentration. Impregnation may be conducted in a variety of ways. Thus, the solution may be flowed over the foam and allowed to enter by gravity, or an external force such as increased pressure vibration or a partial vacuum may be employed. After impregnation is complete, the foam is slowly dried to permit roughly 95 percent of the moisture to evaporate from the coating. This can be accomplished at room temperature, or at slightly elevated temperatures. Once the majority of moisture is removed, the impregnated foam segment is compressed to less than about 50 percent of its original volume. As noted in the above-referenced parent application, compression may be conducted to less than 10% of original volume. Once compressed, the foam may be held at room temperature for a short period of time, or instantaneously constrained by the application of mild heat to harden the coating. The tampon is then complete, and may resemble the illustration of FIG. 3. In an alternate embodiment of the present invention, the citric acid-sodium bicarbonate composition is dry impregnated into the foam before its preparation into segments for particular end products. Referring to FIG. 2, a flow sheet of successive steps for dry impregnation of the foam and the production of articles such as tampons is presented. The hydrophilic foam is formed into a sheet of essentially any reasonable dimensions. For use as a tampon the foam will be formed in a thickness of about 2 inches. The foam sheet is then placed in a chamber and an air stream containing the composition in particulate form is drawn through the foam. The cells of the foam act as a filter and trap most of the solid agent. When the foam contains 10 to 200 percent by weight of the solid agent, it is removed from the air chamber. At this stage, in the manufacture of tampons, the sheet will be cut into individual segments of about 1 inch square. If larger articles are to be manufactured which utilize an entire sheet of foam, or if the foam is initially prepared by a molding process, such as extrusion of a finite length, which yields the ultimately desired shape, this step is eliminated. After impregnation, and, if necessary, cutting the foam is compressed to less than 50 percent of its original volume. In a preferred embodiment which is useful in tampon manufacture, the foam may be compressed from about less than 25 to about less that 10%. Any conventional type of press or device may be used. This operation may also be in combination with that of placing the compressed foam into the constraining device. As previously discussed, the constraining device which may be employed in this technique, is a gelatin capsule or cylinder. The foam segment, which is prepared for tampon manufacture and measures about 1 × 1 × 2 inches, can be compressed and placed with the capsule in a single step by any of the many known techniques. One useful technique is to have a cylindrical mold of the same interior diameter, which cooperates with a ram which axially thrusts into the mold cavity and forces the foam into the capsule. The draw string conventionally attached to the tampon may be stitched into place at any time, either to the foam before encapsulation, or to the encapsulated tampon itself. Once placed in the capsule, the foam can be stored indefinitely. As discussed earlier, the gelatin capsule readily dissolves upon contact with moisture, and the foam rapidly expands to contact the vaginal periphery. The tampons described above may be employed as prepared or may also contain, as desired, various suitable additives such as disinfectants, perfumes, medicaments, deodorants, emollients, pigments and/or dyes. In a further embodiment, the devices of the present invention may be employed to test for the presence of various microorganisms, by the incorporation of suitable chemical indicators. Naturally, the size and shape of the tampons of this invention may vary widely to account for variation in locus of use and function. Thus, as disclosed in our parent application, the tampon, as illustrated in FIG. 3, may be employed alone for use by digital insertion, or may be mounted upon insertion means usually comprising one or more cylindrical tubes, which serve to position and eject the device within the vaginal canal. Throughout the specification, all percentages of ingredients are expressed as percent by weight. This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.
A catamenial device such as a tampon which comprises a segment of a rapidly re-expandable hydrophilic polymeric foam held in compression to less than 50 percent of its original dry volume and a constraining means holding said segment in compression which is adapted to provide lubrication for insertion of said segment into an animal's body cavity and to thereafter rapidly disintegrate, wherein said constraining means comprises a coating material comprising a mixture of sodium bicarbonate and citric acid. Said coating material may be provided by the application of a solution to the surface of said foam segment, or by full impregnation. In a further embodiment, said coating material may be introduced into said foam in particulate form to serve as a novel release agent in a segment which is subsequently constrained within a gelatin capsule.
Identify and summarize the most critical technical features from the given patent document.
[ "CROSS REFERENCE TO RELATED APPLICATIONS This application is a Continuation-In-Part of co-pending Ser.", "No. 436,391 filed on Jan. 24, 1974, by the inventors herein.", "BACKGROUND OF THE INVENTION This invention generally relates to catamenial devices such as tampons and other insertable articles which are prepared from hydrophilic polymeric foam materials.", "As noted in the above-identified co-pending application, catamenial devices such as tampons have been prepared from a wide variety of synthetic and naturally occuring organic materials in the form of fibers and sponge-like materials, but have all suffered from various critical defects.", "Generally, a device such as a tampon which is to be inserted in an easily irritable area of the body cavity must possess a refined texture and flexibility, while, at the same time, possessing a significant absorptive capacity and the ability to rapidly and uniformly re-expand in contact with moisture such as occasioned by the menstrual flow.", "The latter property is required because the device must assume a reduced size to facilitate its insertion.", "Generally, prior art devices have lacked one or more of the above properties, as absorption is usually gained at the expense of size, and flexibility and texture are sacrificed to the ability to undergo re-expansion.", "In the context of the above discussion, Applicants sought to provide a device combining all of the favorable characteristics, and, accordingly, developed a catamenial device prepared from a hydrophilic, rapidly re-expandable polymeric foam which is compressed to less than 50 percent of its dry volume and then placed within a soluble, lubricious constraining means such as a capsule.", "The material most often comprising the capsule of this device is a gelatin compound, which was known to possess the requisite lubricity and solubility as well as non-toxicity to living tissue.", "Further experimentation conducted since the development of the above has uncovered a useful alternate material for the preparation of the constraining means which possesses all of the above properties and is easier and less expensive to employ.", "SUMMARY OF THE INVENTION In accordance with the present invention, a catamenial device is disclosed which comprises a hydrophilic, rapidly reexpandable polymeric foam segment which is compressed and placed within a constraining means for an extended period of time, wherein said constraining means comprises a water-soluble coating formed by a composition comprising citric acid and sodium bicarbonate.", "The coating composition may either be applied topically in solution to the surface of the segment, or the segment may be fully impregnated therewith.", "The composition of the present invention may, in an alternate embodiment, be employed as a release agent, by conducting a dry impregnation of the foam prior to shaping and constraint thereof, as disclosed in the copending parent application noted above.", "Catamenial devices prepared with the coating composition of the invention exhibit favorable storage stability in compression over extended periods of time, and, upon contact with moisture, re-expand rapidly to a volume significantly in excess of original dry volume, due to the effervescence of the composition.", "Tampons prepared in accordance herewith likewise unexpectedly perform a medicinal function, as the presence of the coating composition in the vaginal canal restores the slightly acidic pH necessary to the prevention of vaginitis during the menstrual period.", "Accordingly, it is a principal object of the present invention to provide a catamenial device comprising a hydrophilic polymeric foam held in a compression by a coating composition comprising citric acid and sodium bicarbonate.", "It is a further object of the present invention to provide a device as aforesaid which exhibits improved shelf stability under compression, yet is rapidly re-expandable in contact with moisture.", "It is yet a further object of the present invention to provide a device as aforesaid which renders medicinal assistance to the vaginal area during the menstrual flow.", "It is a still further object of the present invention to provide a method of impregnating a polymeric foam to render said foam more rapidly re-expandable in contact with moisture.", "Other objects and advantages will appear from a consideration of the description and accompanying drawings.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow diagram outlining the preparation of the device of this invention with a full wet impregnation technique.", "FIG. 2 is a flow diagram outlining the dry impregnation of the foam with the coating composition employed in accordance with the invention.", "FIG. 3 is a perspective view of a tampon prepared in accordance with the technique of FIG. 1. DETAILED DESCRIPTION In accordance with the present invention, the foregoing objects and advantages are readily obtained.", "The present invention comprises a catamenial device such as a tampon which is prepared from a rapidly re-expandable hydrophilic polymeric foam segment which is placed in compression and maintained therein by a constraining means comprising a coating prepared from a composition comprising citric acid and sodium bicarbonate.", "The composition may be applied in solution as a surface coating, or the foam segment may be impregnated therewith.", "As a further alternative embodiment, the foam may be dry impregnated with particles of the composition prior to being cut into segments and placed in compression within a constraining means such as a capsule.", "The devices and their general preparation, to which the present invention pertains, are disclosed in our copending parent application Ser.", "No. 436,391, incorporated herein by reference.", "The foams disclosed therein comprise hydrophilic polyurethane foams or hydrophilic formaldehyde polyvinylalcohol foams.", "It is preferred, however, that the foam be hydrophilic polyurethane foam.", "A commercially available hydrophilic polyurethane foam is marketed under the tradename Acquell®and is available from the Scott Paper Company.", "This is a polyurethane foam produced by the reaction of a polyesterdiol and tolylene diisocyanate.", "The polyesterdiol also contains adipic acid and block copolymers of polyoxyethylene and polyoxypropylene.", "Another foam which may be used in accordance with this invention is prepared by, in a in a first step, forming a prepolymer by the reaction of polyethylene glycol and trimethylol propane in a mole ratio of about 2:0.125 to 2:2 respectively, followed by capping the reaction product at all hydroxy locations using tolylene diisocyanate consisting of about an 80/20 mixture of the 2,4 isomer to 2,6 isomer;", "and in a second step reacting 100 parts by weight of prepolymer with 30 parts by weight of water containing 5 parts by weight of a polyoxyalkylene non-ionic surfactant.", "A particular non-ionic surfactant which has been found useful is one commercially available under the tradename Pluronic L-64 from the Wyandotte Chemicals Corporation.", "Although the above comprise the preferred hydrophilic urethane foam materials, other useful hydrophilic urethane foams are produced by varying the above prepolymer to water ratio, as well as varying the water to surfactant ratio.", "Polymeric foams which are to be employed in the preparation of a tampon assembly should preferably possess a maximum density of about 2.5 lbs.", "/ft.", "3 , as difficulties arise in the compression and encapsulation of foams whose density exceeds this level.", "The general preparation of the constrained device comprises the compression of the foam followed by insertion in the compressed state into a constraining means such as a capsule.", "Compression of the foam is usually conducted to a reduction of at least about 50% of its original dry volume, and in a preferred embodiment which is useful in tampon manufacture, the foam may be compressed from about less than 25 to about less than 10%.", "Any conventional type of press or device may be used.", "This operation may also be in combination with that of placing the compressed foam into the constraining means.", "The constraining means employed therein comprise a pre-formed capsule structure which, in a preferred embodiment, is prepared from a water-soluble non-toxic material such as gelatin.", "The adhesive coating composition comprising the constraining means of the present invention is a mixture of sodium bicarbonate and citric acid employed in roughly equal amounts.", "It has been discovered that the above mixture serves as a binder when placed on a foam segment and dried, and additionally, when subsequently wetted, provides sufficient effervescence to serve as a blowing agent which enhances the re-expansion of the foam.", "Beyond the above advantages, the composition of this invention also possesses a medicinal utility, as it provides a slightly acidic environment which is particularly useful in the vaginal area during the menstrual flow, and prevents the occurrence of vaginitis, which generally resulting from a loss of beneficial bacteria and a change toward an environment of slightly alkaline pH.", "The restoration of a slightly acidic environment also prevents the undue accumulation of noxious odor and irritation which results from the enzymatic reduction of the uric acid, urea, amino acids and the like constituting the menstrual discharge, to ammonia and volatile amines.", "As stated above, the sodium bicarbonate-citric acid composition of the invention may roughly comprise equal amounts of each ingredient.", "Specifically, the amounts of each may vary within 10%, so that both citric acid and sodium bicarbonate may be present in amounts ranging from 40 to 60% by weight of the total composition.", "Preparation in the above range has been found to impart the combination of desirable characteristics enumerated earlier.", "The composition may be employed in the catamenial device in a number of ways;", "as a constraining means applied as a topical liquid coating which dries to form an adhesive outer coat, or by thorough wet impregnation to reside throughout the device.", "If topical or surface application is employed, the foam segment should first be coated with the composition, after which it may be constrained to the desired volume.", "When the composition is to be employed in liquid form, it should be dispersed in water in a ratio thereto ranging from approximately 1:1 to 5:1 water to composition.", "When the composition is to be employed strictly as a topical adhesive, the preferred ratio comprises 1:1, as a highly viscous solution results which rapidly fixes the surface of the compressed foam in position.", "If full impregnation is desired, however, a more dilute solution is preferred to enable the composition to completely and uniformly penetrate the entire segment.", "Referring now to FIG. 1, a flow diagram set out the steps for full wet impregnation of the foam segment.", "The foam is first prepared to the shape of the final article, which, as illustrated herein, is a tampon.", "The foam will be cut to dimensions of about 1 × 1 × 2 inches which correspond to the size of a tampon device.", "The resulting foam segment is impregnated with a solution of the citric acid-bicarbonate composition, which is preferably employed at a 20 percent concentration.", "Impregnation may be conducted in a variety of ways.", "Thus, the solution may be flowed over the foam and allowed to enter by gravity, or an external force such as increased pressure vibration or a partial vacuum may be employed.", "After impregnation is complete, the foam is slowly dried to permit roughly 95 percent of the moisture to evaporate from the coating.", "This can be accomplished at room temperature, or at slightly elevated temperatures.", "Once the majority of moisture is removed, the impregnated foam segment is compressed to less than about 50 percent of its original volume.", "As noted in the above-referenced parent application, compression may be conducted to less than 10% of original volume.", "Once compressed, the foam may be held at room temperature for a short period of time, or instantaneously constrained by the application of mild heat to harden the coating.", "The tampon is then complete, and may resemble the illustration of FIG. 3. In an alternate embodiment of the present invention, the citric acid-sodium bicarbonate composition is dry impregnated into the foam before its preparation into segments for particular end products.", "Referring to FIG. 2, a flow sheet of successive steps for dry impregnation of the foam and the production of articles such as tampons is presented.", "The hydrophilic foam is formed into a sheet of essentially any reasonable dimensions.", "For use as a tampon the foam will be formed in a thickness of about 2 inches.", "The foam sheet is then placed in a chamber and an air stream containing the composition in particulate form is drawn through the foam.", "The cells of the foam act as a filter and trap most of the solid agent.", "When the foam contains 10 to 200 percent by weight of the solid agent, it is removed from the air chamber.", "At this stage, in the manufacture of tampons, the sheet will be cut into individual segments of about 1 inch square.", "If larger articles are to be manufactured which utilize an entire sheet of foam, or if the foam is initially prepared by a molding process, such as extrusion of a finite length, which yields the ultimately desired shape, this step is eliminated.", "After impregnation, and, if necessary, cutting the foam is compressed to less than 50 percent of its original volume.", "In a preferred embodiment which is useful in tampon manufacture, the foam may be compressed from about less than 25 to about less that 10%.", "Any conventional type of press or device may be used.", "This operation may also be in combination with that of placing the compressed foam into the constraining device.", "As previously discussed, the constraining device which may be employed in this technique, is a gelatin capsule or cylinder.", "The foam segment, which is prepared for tampon manufacture and measures about 1 × 1 × 2 inches, can be compressed and placed with the capsule in a single step by any of the many known techniques.", "One useful technique is to have a cylindrical mold of the same interior diameter, which cooperates with a ram which axially thrusts into the mold cavity and forces the foam into the capsule.", "The draw string conventionally attached to the tampon may be stitched into place at any time, either to the foam before encapsulation, or to the encapsulated tampon itself.", "Once placed in the capsule, the foam can be stored indefinitely.", "As discussed earlier, the gelatin capsule readily dissolves upon contact with moisture, and the foam rapidly expands to contact the vaginal periphery.", "The tampons described above may be employed as prepared or may also contain, as desired, various suitable additives such as disinfectants, perfumes, medicaments, deodorants, emollients, pigments and/or dyes.", "In a further embodiment, the devices of the present invention may be employed to test for the presence of various microorganisms, by the incorporation of suitable chemical indicators.", "Naturally, the size and shape of the tampons of this invention may vary widely to account for variation in locus of use and function.", "Thus, as disclosed in our parent application, the tampon, as illustrated in FIG. 3, may be employed alone for use by digital insertion, or may be mounted upon insertion means usually comprising one or more cylindrical tubes, which serve to position and eject the device within the vaginal canal.", "Throughout the specification, all percentages of ingredients are expressed as percent by weight.", "This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof.", "The present embodiment is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein." ]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed in general to digital representation of analog signals, and more particularly to a system for development of sequential digital profiles from selective analog signals, for the future application in processing analog signals. 2. Description of the Background Art Due to the real-time performance requirements, recent demand for effective digital representation of on-line analog signal message in a wide diversity of emerging transaction-oriented applications such as smart card, signature identification, data security, speech recognition, medical diagnosis, and other applications, have required novel methods to be explored and introduced for improving the real time computation performance of incoming analog signals. Namely, for these emerging transaction-oriented applications, the signal channels would typically remain silent until selective authorized users have made and initiated a particular request for the channel usage. The incoming signal message will then be comprised of an unique user identification signal, followed by a sequence of commands, and their relevant data. Due to their nature, such transactions can happen at any of the time instances, and occur in a totally random order. Therefore, unless prior to the entire signal conversion is completed, selective digital representation can be made available to facilitate the on-line computation and verification of the user identification signal, it is really not possible to predict, anticipate and schedule these events in real time employing traditional scheduling, optimization, and computation methods as described in the background arts. On the other hands, there are plenty of background arts which taught digital representation methods for the traditional time-continuous processing applications, namely digitization, coding, and signal conversion methods which continuously allow the entire analog signal for translating into an efficient digital representation. Nevertheless, the major objective of these background arts would be to provide parallel and/or pipeline hardware computation for digital representation after the entire signal conversion is completed. For example, Pulse Code Modulation (PCM), Fast Fourier Transform (FFT), and Discrete Cosine Transform (DCT) methods have been illustrated by Stem S. D. and Hush, D. R., in "Digital Signal Analysis", Prentice Hall, 1990, Michael Julian in "Circuit, Signal and Devices", John Wiley and Sons, 1989, and Rao S., Kailath T. in "Regular Iterative Algorithm and Their Implementation in Processor Arrays" Proceeding of IEEE 1988. In the relevant field of cryptography, similar situation remains. Namely, there are plenty of background arts which taught how to apply sophisticated digital mathematical algorithms, protocols, or coding techniques to improve the design of a digital representation for the stored security key and the embedded encryption algorithm. For example, Man Y. R. in "Cryptography and Secure Communications", McGraw Hill, 1994, and Shannon in "A Mathematical Theory of Communications", Bell System Technical Journal, Volume 27, 1948. However, no matter how complex the algorithm may be, a single digital representation can only translate into a single analog waveform representation for a stored key. Therefore, for highly confidential signal communications, although it is extremely desirable to apply multiple analog waveforms for assisting the encryption of the signal sequence, since multiple digital algorithms are required, this is often discouraged due to the difficulty, complexity, and cost associated with the real-time on-line decryption. These methods, though practical, are obviously ineffective for the transaction-processing oriented applications. First, they would require expensive high-speed processing and memory circuits in order to reach the real time performance. Furthermore, these circuits must be constantly active in order to continuously monitor the signal channel for any incoming signal sequence. Finally, none of these methods have ever taught how to discriminate and eliminate the unauthorized or uninterested signals in the analog domain, namely prior to the analog to digital signal conversion, in order to eliminate further storage and processing at the digital domain. It is conceived that these background arts will impose serious cost and power consumption disadvantage for their product implementation, and subsequently limit the market realization potential of these emerging technologies and applications. In light of these storage and performance problems, prior to acceptance of the entire on-line analog signals and their conversion from analog into the digital domain, some form of novel digital representation method is necessary in order to validate and initiate the transaction process, namely, provide the front-end-detection and discrimination method to prevent unauthorized or uninterested on-line analog signal processing. It would be also necessary to make such method programmable, whereby a single digital representation can be programmed to adapt with various application environments. Finally, it is further necessary to make such computation method simple yet effective so that the product realization can become economical and affordable at the marketplace. To date, no single representation possesses the necessary computation and storage power, yet would only require nominal cost for its implementation, in order to process the incoming analog bit-stream at the necessary real time performance. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a system method for creating digital representation of analog signals, and more particularly to provide a system method for development of a sequential digital profile from selective incoming analog signals, for the future application in processing analog signals. It is still further an object of the present invention to generalize said analog signals for including time-domain analog signals representing selective physical phenomena. It is still further an object of the present invention to perform on-line segmentation of said incoming analog signals according to a sequence of threshold values. It is still further an object of the present invention to represent results of said segmentation through on-line computation of a sequence of measurements in accordance with selective attributes of said analog signals. It is further an object of the present invention to determine rules, conditions, and algorithms for the development of said sequential digital profile from said results of segmentation and said sequence of measurements. It is further an object of the present invention to apply said sequential digital profiles for the encryption, protection and decryption of analog signal sequences through conforming the behavior of front-end-identification fragments and/or inserted identification fragments of said sequences with said sequential digital profiles. A preferred embodiment of the present invention consists of three modules. The first module is an on-line module incorporating an input device, a memory device, a control unit, and a processing unit. The second module is an off-line module analysing results received from said on-line module in order to develop a sequential digital profile. The third module is a signal generator which can generate random analog signals conforming with said sequential digital profile. The input device of said on-line module acquires incoming analog signals. The memory device of said on-line module contains a predefined sequence of threshold values. Each element of said sequence of threshold values consists of: (i) a lower threshold value; (ii) a higher threshold value. The memory device of said on-line module is also used to memorize measurements performed by the processing unit of said on-line module. The control unit of said on-line module supervises other components of said on-line module according to a control algorithm. The general idea of the control algorithm performed by the control unit of said on-line module is as follows: (i) activate receiving an incoming analog signal by the input device; (ii) from the memory device, retrieve the first element of said sequence of threshold values, i.e. the first lower threshold value and the first higher threshold value; (iii) send to the processing unit retrieved lower threshold value and retrieved higher threshold value; (iv) wait until measurements are received from the processing unit; (v) memorize said received measurements in the memory device; (vi) if the retrieved element of said sequence of threshold values is the last one then quit the algorithm; (vii) retrieve the(next element of said sequence of threshold values and go to (iii). The algorithm can be interrupted or suspended at any moment when no incoming analog signal is available from the input device. The algorithm should be run (using the same sequence of threshold values) for several incoming analog signals representing the same class of signals. The processing unit of said on-line module performs selective operations on said incoming analog signals. This includes on-line attribute measurements according to the predefined list of attributes, and on-line segmentation according to the range thresholds (i.e. the lower threshold and the higher threshold) received from the control unit. The general idea of the operations performed by the processing unit is as follows: (i) perform on-line computation of attribute measurements, until the magnitude of the incoming signal is within said range received from the control unit (detecting the beginning of a segment); the computed measurements are called off-segment attribute measurements; (ii) perform on-line computation of attribute measurements, until the magnitude of the incoming signal quits said range received from the control (detecting the end of a segment), the computed measurements are called in-segment attribute measurements; (iii) send the computed off-segment attribute measurements and in-segment attribute measurements to the control unit, and go to (i). It is envisaged that in the practical applications of the invention selected steps of both above-mentioned algorithms can be performed parallelly and/or asynchronously in order to minimize delays and avoid discontinuities in processing the incoming analog signals. The off-line module of the preferred embodiment interprets the results received from said on-line module in order to develop a sequential digital profile. The off-line module can be a general purpose computing system which has an access to the content of said memory device of the on-line module. A single sequential digital profile consists of the following components: (a) a sequence of samples consisting of two values: a lower threshold value and a higher threshold value (the range of a sample); (b) a list of attributes divided into two subsets: in-segment attributes and off-segment attributes; (c) attribute values of said list of attributes for each sample of said sequence of samples. The following analysis is performed to create the abovementioned components of a sequential digital profile: (a) said sequence of samples directly corresponds to said sequence of threshold values; (b) said list of attributes is selected from the attributes which can be measured by said processing unit of the on-line module; the analysis of off-segment measurements received from the on-line module determines which attributes are to be off-segment attributes of said list of attributes, and the analysis of in-segment measurements received from the on-line module determines which attributes are to be in-segment attributes of said list of attributes; human assistance might be required to perform the analysis; (c) attribute values for each sample of said sequence of samples are determined through the analysis of off-segment measurements and in-segment measurements received from the on-line module for several incoming analog signals. The third module, i.e. the signal generator of random analog signals conforming with a sequential digital profile taken from the off-line module, consists of the following components: (a) a general application computing unit with random-number generating facilities; (b) a memory unit; (c) a digital-to-analog converter. Said computing unit generates a digital signal conforming with said sequential digital profile. Said signal is represented by a sequence of numbers randomly generated according to the conditions imposed by said sequential digital profile. Said sequence of numbers is stored in the memory unit. The digital-to-analog converter converts the content of the memory unit into an analog signal. The process of generation of analog signals can be performed either off-line (the whole sequence of numbers is memorized, and then converted to an analog signal) or on-line (each generated number of said sequence of numbers is immediately converted to an analog value) depending on the performances of said computing unit. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein: FIG. 1 is a general block diagram illustrating major components and data flow in a preferred embodiment of the present invention. FIG. 2 shows a general structure of the processing unit. FIG. 3 shows a general structure Of a sequence of threshold values. FIG. 4 is a flowchart illustrating in a broad sense the steps of the algorithm performed in the control unit of the preferred embodiment of the present invention. FIG. 5 is a flowchart illustrating in a broad sense the steps of the algorithm performed in the processing unit of the preferred embodiment of the present invention. FIG. 6 shows an example of the processing unit which can perform computation of selective attribute measurements. FIG. 7 shows an example of a sequence of threshold values according to the general structure of FIG. 3. FIGS. 8 to 11 show examples of incoming analog signals and results of the processing performed by the algorithm of FIG. 4 using processing unit of FIG. 6, and the sequence of threshold values of FIG. 7. FIG. 12 shows a general structure of a sequential digital profile. FIG. 13 shows an example of a sequential digital profile obtained from the results shown in FIGS. 8 to 11, according to the general structure of FIG. 12. FIG. 14 is a general block diagram of a module generating analog signals conforming with a sequential digital profile. FIG. 15 shows examples of analog signals generated by the module of FIG. 14, and conforming with the sequential digital profile of FIG. 13. DESCRIPTION OF THE PREFERRED EMBODIMENT In the following description, particular reference is made to the implementation of the invention in the context of processing voltage signals. It is envisaged, however, that the practical applications of the invention can be extended to many other areas in which selective physical phenomena would be represented by the analog, time-domain signals. Referring to FIG. 1, the preferred system in which the present invention would be applied consists of the on-line module 10 and the off-line module 15. The on-line module 10 incorporates the input device 11, the processing unit 12, the control unit 13, and the memory device 14 Incoming analog signals 20 are acquired from the input device 11, which is capable to capture continuously the magnitude of the signals. Acquisition of an incoming signal is activated by the signal 21 received from the control unit 13. The incoming signal 20 will be denotes as X(t). The signal 12 is to inform the control unit that no incoming signal is being received. Usually this should suspend or interrupt the control algorithm run by the control unit 13. The incoming signal 10 is processed in the processing unit 12 according to the predefined list of attributes 70, and the range 50 (determined by the higher threshold value 51 and the lower threshold value 52) received from the control unit 13. This includes extraction of continuous segments of the incoming signal 20 being within the range 50, as well as computation of attribute measurements 30 according to the attributes 70. The processing unit 12 is equipped with the devices capable to perform the required computation on-line. The computed attribute measurements 30 are sent to the control unit 13. The control unit 13 runs a control algorithm, memorizes in the memory device 14 the attribute measurements 30 received from the processing unit 12, and retrieves the sequence of threshold values 23 from said memory device 14. The range 50 (i.e. the threshold values 51 and 52) which is being send to processing 12 is extracted from the sequence of threshold values 23. The off-line module 15 accumulates the attribute measurements 30 extracted from the memory device 14 in order to create a sequential digital profile 25. The off-line module 15 can be also used to load the sequence of threshold values 23 to said memory device 14. A sequential digital profile 25 is sent to the signal generator 26 which can generate random analog signals 27 conforming with said sequential digital profile 25. Referring to FIG. 2, a general structure of the processing unit 12 comprises the following components: the modules 120 performing on-line computation of attribute measurements 30 for the predetermined list 70 of M attributes {A1, A2, . . . , AM}; in order to improve on-line performances of the system, each module 120 consists of two identical units 121 and 122; the unit 121 performs off-segment measurements 33 while the unit 122 performs in-segment measurements 34; the threshold buffers 123 and 124 containing the higher threshold value 51 and the lower threshold value 52 respectively; the range selector 125 detecting whether the current magnitude of the incoming signal 20 is within the range defined by the thresholds 51 and 52 received from the buffers 123 and 124 respectively; the measurement buffer 130 (consisting of the off-segment buffer 131 and the in-segment buffer 132) memorizing the attribute measurements 30 comprising the off-segment measurements 33 and the in-segment measurements 34, wherein the off-segment attribute measurements 33 are received from the modules 121 and memorized in the buffer 131, while the in-segment attribute measurements 34 are received from the modules 122 and memorized in the buffer 132. The reset signals 141 and the load signal 151 are arranged so that the off-segment measurements 33 are computed when the incoming signal 20 is outside the range defined by the thresholds 51 and 52, and said measurements are memorized in the buffer 131 when the incoming signal 20 enters said range. The reset signals 142 and the load signal 152 are arranged so that the in-segment measurements 34 are computed when the incoming signal 20 is within the range defined by-the thresholds 51 and 52, and said measurements are memorized in the buffer 132 when the incoming signal 20 quits said range. Referring to FIG. 3, the sequence of threshold values 23 stored in the memory device 14 consists of N elements {S1, S2, . . . , SN} wherein each Si incorporates: (i) the higher threshold value HTi (51); (ii) the lower threshold value LTi (52). Referring to FIG. 4, the algorithm performed in the control unit 13 comprises the following steps: Step 100 Send the signal 21 to initialize acquisition of an incoming analog signal 20 X(t) from the input device 11. Step 101 Set i=1. Step 102 Retrieve the element Si from the sequence of threshold values 23. Step 103 For the retrieved element Si, send the higher threshold value HTi (51) and the lower threshold value LTi (52) to the buffers 123 and 124 of the processing unit 12. Step 104 Wait until the off-segment measurements 33 {MeOFA 1 , MeOFA 2 , . . . , MeOFA M } and the in-segment measurements 34 {MeINA 1 , MeINA 2 , . . . , MeINA M } are received from the buffers 131 and 132 of the processing unit 12. Step 105 Memorize the off-segment measurements 33 {MeOFA 1 , MeOFA 2 , . . . , MeOFA M } and the in-segment measurements 34 {MeINA 1 , MeINA 2 , . . . , MeINA M } in the memory device 14. ______________________________________Step 106 If (i < N) then i = i + 1; goto Step 102elseexit.______________________________________ The algorithm can be suspended or terminated at any moment when the signal 22 is received from the processing unit 12, i.e. when no incoming signal 20 is available. The abovementioned algorithm is given by way of illustration and example only and is not to be taken by way of limitation, so that in the future embodiments other algorithms 15 based on the same principles could be applied. In particular, selected steps of the algorithm can be, .performed parallelly, asynchronously or can be pipelined in order to minimize delays and avoid discontinuities in processing the incoming analog signal 20. Referring to FIG. 5, the algorithm performed in the processing unit 12 has the following structure: Step 200 Perform on-line computation of off-segment measurements 33 using. modules 121 until the magnitude of X(t) is inside the range defined by the content of the threshold buffers 123 and 124. Step 201 Memorize said measurements 33 of Step 200 in the measurement buffer 131, and reset the modules 122. Step 202 Perform on-line computation of in-segment measurements 34 using modules 122 until the magnitude of X(t) is outside the range defined by the content of the threshold buffers 123 and 124. Step 203 Memorize said measurements 34 of Step 202 in the measurement buffer 132, and reset the modules 121. Step 204 Goto Step 200. FIG. 6 shows a design of a processing unit 12 which can perform attribute measurements for the following list of attributes 70: {A.sub.1 =Period.sub.-- of.sub.-- duration, A.sub.2 =Type.sub.-- of.sub.-- monotonicity}. The structure of the unit corresponds to the general structure of FIG. 3. The range selector 125 consists of two analog comparators 251 and 252 comparing the incoming signal 20 to the content of the range buffers 123 and 124 respectively. The AND-gate 253 provides that the binary output 254 of the range selector 125 is set ONE when the incoming signal 20 is within said range, and ZERO otherwise. There are two modules 121 and two corresponding modules 122, i.e. the modules to perform Period -- of -- duration measurements, and the modules to perform Type -- of -- monotonicity measurements. The module 121-1 performing Period -- of -- duration measurements consists of the digital counter 211 with the reset signal 141 connected to the ouput 254. The clock input of the counter 211 is connected to the external signal generator. The module 121-2 performing Type -- of -- monotonicity measurements consists of two flip-flops 214 and 215, which receive signals from the differentiating element 212 through the sign detector 213. The small histeresis loop has been added in the sign detector 213 in order to compensate minor variations of the incoming signal 20. The flip-flop 214 is set whenever the derivative of the incoming signal 20 is positive, and the flip-flop 215 is set whenever the derivative of the incoming signal 20 is negative. The reset signal 141 resets the flip-flops 214 and 215 and closes their Set input AND-gates. The modules 122 have the identical structure to the corresponding modules 121. The only difference is that the reset signal 142 is connected to the inverted output 254. The measurement buffer 131 is a latch register with two inputs connected to flip-flops 214 and 215, and the rest of inputs connected to the counter 211. The load signal 151 is connected to the inverted output 254. The measurement buffer 132 is similar to the buffer 131. The only difference is that the load signal 152 is connected to the output 254. Therefore, the attribute measurements 30 (comprising off-segment measurements 33 and in-segment measurements 34) are represented as follows: Off-segment Period -- of -- duration--the corresponding output bits of the buffer 131; Off-segment Type -- of -- monotonicity--two output bits of the buffer 131, wherein 01 represents "decreasing"; 10 represents "increasing"; 11 represents "no -- monotonicity"; In-segment Period -- of -- duration--the corresponding output bits of the buffer 132; In-segment Type -- of -- monotonicity--two output bits of the buffer 132, wherein 01 represents "decreasing"; 10 represents "increasing"; 11 represents "no -- monotonicity". FIG. 7 shows an example of a sequence of threshold values 23 according to the general structure of FIG. 3 wherein: (i) the sequence of threshold values 23 contains four elements: S1, S2, S3, S4; (ii) the threshold values 51 and 52 for the given elements are: ______________________________________ HT.sub.1 = 1.4 LT.sub.1 = 1.0; HT.sub.2 = 2.2 LT.sub.2 = 2.0; HT.sub.3 = 0.8 LT.sub.3 = 0.4; HT.sub.4 = 1.5 LT.sub.4 = 1.2.______________________________________ FIGS. 8 to 11 show examples of incoming analog signals 20 being processed by the algorithm of FIG. 4 using processing unit of FIG. 6 and the sequence of threshold values 23 of FIG. 7. The extracted segments 81, 82, 83 and 84 correspond respectively to the elements S1, S2, S3 and S4 from the sequence of threshold values 23. The lists 91, 92, 93 and 94 contain the corresponding attribute measurements 33 and 34, wherein: ______________________________________OFA.sub.1 is the off-segment Period.sub.-- of.sub.-- duration,OFA.sub.2 is the off-segment Type.sub.-- of.sub.-- monotonicity,INA.sub.1 is the in-segment Period.sub.-- of.sub.-- duration,INA.sub.2 is the in-segment Type.sub.-- of.sub.-- monotonicity,and"-" represents "decreasing","+" represents "increasing","-/+" represents "no.sub.-- monotonicity".______________________________________ Sequential digital profiles 25 would be created using: (i) the sequence of threshold values 23; (ii) the predetermined list 70 attributes; (iii) the attribute measurements 33 and 34 computed for the given examples of incoming analog signals 20. Since the incoming analog signals 20 are supposed to be typical samples of the signals of interest, the corresponding digital profile 25 should be a generalization of the available attributes 70 and the attribute measurements 33 and 34. Said generalization might be performed automatically or might require human assistance. Referring to FIG. 12, sequential digital profiles 25 consist in general of the following components: (i) the sequence of N samples {S1, S1, . . . , SN} corresponding to the sequence of threshold values 23 stored in the memory device 14, wherein each sample Si (i=1 , . . . , N) has its range 50 bounded by the higher threshold value HTi (51) and the lower threshold value LTi (52); (ii) the list of attributes 60 consisting of off-segment attributes 61 {OFA 1 , OFA 2 , . . . , OFA v } and in-segment attributes 62 {INA 1 , INA 2 , . . . , INA w }, wherein both off-segment attributes 61 and in-segment attributes 62 are selected from the predetermined list 70 of M attributes {A1, A2, . . . , AM}; (iii) for each sample Si(i=1, . . . , n), the sequence of off-segment attribute values 63 {OFA 1 (Si), OFA 2 (Si), . . . , OFA v (Si)}; (iv) for each sample Si (i=1, . . . , N), the sequence of in-segment attribute values 64 {INA 1 (Si), INA 2 (Si), . . . , INA w (Si)}. Therefore, FIG. 13 shows an example of a sequential digital profile 25 obtained from the results given in FIGS. 8 to 11, according to the general structure of FIG. 12. Note that the in-segment attributes 62 do not include the Type -- of -- monotonicity attribute. This because for this attribute the natural generalization of the results of FIGS. 8 to 11 would give "don't care" value for each created sample Si (i=1, . . . , 4). The values of the Period -- of -- duration attribute have been rounded with 0.1 sec accuracy. The digital profile of FIG. 13 is given by way of illustration and example only and is not to be taken by way of limitation, so that in the future embodiments other methods of generalization based on the same principles could be applied. Referring to FIG. 14, a general structure of the signal generator 26 generating random analog signals conforming with a sequential digital profile 25 taken from the off-line module 15, consists of the following components: (i) a general application computing unit 40 incorporating a generator 41 of random numbers; (ii) a dual-port memory unit 42; (iii) a digital-to-analog converter 43; (iv) an output address counter 44 for the memory unit 42. The computing unit 40 receives a sequential digital profile 25 from the off-line module 15, and generates a random sequence of numbers 45 which is memorized in the memory unit 42. The sequence 45 reappears on the output of the memory unit 42 as a digital signal 46 with a sampling period determined by the dock signal 47 connected to the output address counter 44. The digital signal 46 is converted into an output analog signal 27 by the digital-to-analog converter 43. The sequence 45 is generated according to the conditions imposed by said sequential digital profile 25. For example, for the sequential digital profile 25 of FIG. 13, the first numbers of the corresponding sequence 45 should be in an increasing order, and a number corresponding to some randomly selected moment between 0.2 sec and 1.4 sec should reach the magnitude 1.4. The impulse 48 resets the counter 44 and activates the D/A converter 43. Therefore, the process of generation of the output analog signal 27 can be performed either on-line or off-line, depending on the performances of the computing unit 40. If the computing 40 can generate the sequence 45 with a speed exceeding the frequency of the clock 47, the impulse 48 should appear immediately after the first number of the sequence 45 is memorized into the memory unit 42. Otherwise, the impulse 48 should appear after the whole sequence 45 has been memorized into the memory unit 42. The output signal 27 is being sent to an external transmit data assembler 28 which includes the signal 27 into an encrypted analog signal 29 either as a front-end-identification signal or as an inserted identification signal. front-end-identification signal and/or any identification signal inserted within FIG. 15 shows examples of generated analog signals conforming with the sequential digital profile 25 of FIG. 13. The fragments 71, 72, 73 and 74 correspond respectively to the samples S1, S2, S3 and S4 of said sequential digital profile 25 of FIG. 13. Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
An object of the present invention is to provide a method for creating an unique digital representation of multiple analog signals, and more particularly to provide a method for development of a sequential digital profile from selective incoming analog signals, for the future application in processing analog signals. The method is based performing on-line segmentation of incoming analog signals according to a sequence of threshold values. The results of the segmentation are represented by a sequence of measurements corresponding to selective attributes describing analog signals. Then, the results of segmentation performed for many incoming analog signals are generalized using selective rules, conditions, and algorithms, in order to develop a sequential digital profile from sequences of measurements. Sequential digital profiles can be applied for the encryption, protection and decryption of analog signal sequences through conforming the behavior of front-end-identification fragments and/or inserted identification fragments of the analog signal sequences with provided sequential digital profiles.
Summarize the document in concise, focusing on the main idea's functionality and advantages.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention The present invention is directed in general to digital representation of analog signals, and more particularly to a system for development of sequential digital profiles from selective analog signals, for the future application in processing analog signals.", "Description of the Background Art Due to the real-time performance requirements, recent demand for effective digital representation of on-line analog signal message in a wide diversity of emerging transaction-oriented applications such as smart card, signature identification, data security, speech recognition, medical diagnosis, and other applications, have required novel methods to be explored and introduced for improving the real time computation performance of incoming analog signals.", "Namely, for these emerging transaction-oriented applications, the signal channels would typically remain silent until selective authorized users have made and initiated a particular request for the channel usage.", "The incoming signal message will then be comprised of an unique user identification signal, followed by a sequence of commands, and their relevant data.", "Due to their nature, such transactions can happen at any of the time instances, and occur in a totally random order.", "Therefore, unless prior to the entire signal conversion is completed, selective digital representation can be made available to facilitate the on-line computation and verification of the user identification signal, it is really not possible to predict, anticipate and schedule these events in real time employing traditional scheduling, optimization, and computation methods as described in the background arts.", "On the other hands, there are plenty of background arts which taught digital representation methods for the traditional time-continuous processing applications, namely digitization, coding, and signal conversion methods which continuously allow the entire analog signal for translating into an efficient digital representation.", "Nevertheless, the major objective of these background arts would be to provide parallel and/or pipeline hardware computation for digital representation after the entire signal conversion is completed.", "For example, Pulse Code Modulation (PCM), Fast Fourier Transform (FFT), and Discrete Cosine Transform (DCT) methods have been illustrated by Stem S. D. and Hush, D. R., in "Digital Signal Analysis", Prentice Hall, 1990, Michael Julian in "Circuit, Signal and Devices", John Wiley and Sons, 1989, and Rao S., Kailath T. in "Regular Iterative Algorithm and Their Implementation in Processor Arrays"", "Proceeding of IEEE 1988.", "In the relevant field of cryptography, similar situation remains.", "Namely, there are plenty of background arts which taught how to apply sophisticated digital mathematical algorithms, protocols, or coding techniques to improve the design of a digital representation for the stored security key and the embedded encryption algorithm.", "For example, Man Y. R. in "Cryptography and Secure Communications", McGraw Hill, 1994, and Shannon in "A Mathematical Theory of Communications", Bell System Technical Journal, Volume 27, 1948.", "However, no matter how complex the algorithm may be, a single digital representation can only translate into a single analog waveform representation for a stored key.", "Therefore, for highly confidential signal communications, although it is extremely desirable to apply multiple analog waveforms for assisting the encryption of the signal sequence, since multiple digital algorithms are required, this is often discouraged due to the difficulty, complexity, and cost associated with the real-time on-line decryption.", "These methods, though practical, are obviously ineffective for the transaction-processing oriented applications.", "First, they would require expensive high-speed processing and memory circuits in order to reach the real time performance.", "Furthermore, these circuits must be constantly active in order to continuously monitor the signal channel for any incoming signal sequence.", "Finally, none of these methods have ever taught how to discriminate and eliminate the unauthorized or uninterested signals in the analog domain, namely prior to the analog to digital signal conversion, in order to eliminate further storage and processing at the digital domain.", "It is conceived that these background arts will impose serious cost and power consumption disadvantage for their product implementation, and subsequently limit the market realization potential of these emerging technologies and applications.", "In light of these storage and performance problems, prior to acceptance of the entire on-line analog signals and their conversion from analog into the digital domain, some form of novel digital representation method is necessary in order to validate and initiate the transaction process, namely, provide the front-end-detection and discrimination method to prevent unauthorized or uninterested on-line analog signal processing.", "It would be also necessary to make such method programmable, whereby a single digital representation can be programmed to adapt with various application environments.", "Finally, it is further necessary to make such computation method simple yet effective so that the product realization can become economical and affordable at the marketplace.", "To date, no single representation possesses the necessary computation and storage power, yet would only require nominal cost for its implementation, in order to process the incoming analog bit-stream at the necessary real time performance.", "SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a system method for creating digital representation of analog signals, and more particularly to provide a system method for development of a sequential digital profile from selective incoming analog signals, for the future application in processing analog signals.", "It is still further an object of the present invention to generalize said analog signals for including time-domain analog signals representing selective physical phenomena.", "It is still further an object of the present invention to perform on-line segmentation of said incoming analog signals according to a sequence of threshold values.", "It is still further an object of the present invention to represent results of said segmentation through on-line computation of a sequence of measurements in accordance with selective attributes of said analog signals.", "It is further an object of the present invention to determine rules, conditions, and algorithms for the development of said sequential digital profile from said results of segmentation and said sequence of measurements.", "It is further an object of the present invention to apply said sequential digital profiles for the encryption, protection and decryption of analog signal sequences through conforming the behavior of front-end-identification fragments and/or inserted identification fragments of said sequences with said sequential digital profiles.", "A preferred embodiment of the present invention consists of three modules.", "The first module is an on-line module incorporating an input device, a memory device, a control unit, and a processing unit.", "The second module is an off-line module analysing results received from said on-line module in order to develop a sequential digital profile.", "The third module is a signal generator which can generate random analog signals conforming with said sequential digital profile.", "The input device of said on-line module acquires incoming analog signals.", "The memory device of said on-line module contains a predefined sequence of threshold values.", "Each element of said sequence of threshold values consists of: (i) a lower threshold value;", "(ii) a higher threshold value.", "The memory device of said on-line module is also used to memorize measurements performed by the processing unit of said on-line module.", "The control unit of said on-line module supervises other components of said on-line module according to a control algorithm.", "The general idea of the control algorithm performed by the control unit of said on-line module is as follows: (i) activate receiving an incoming analog signal by the input device;", "(ii) from the memory device, retrieve the first element of said sequence of threshold values, i.e. the first lower threshold value and the first higher threshold value;", "(iii) send to the processing unit retrieved lower threshold value and retrieved higher threshold value;", "(iv) wait until measurements are received from the processing unit;", "(v) memorize said received measurements in the memory device;", "(vi) if the retrieved element of said sequence of threshold values is the last one then quit the algorithm;", "(vii) retrieve the(next element of said sequence of threshold values and go to (iii).", "The algorithm can be interrupted or suspended at any moment when no incoming analog signal is available from the input device.", "The algorithm should be run (using the same sequence of threshold values) for several incoming analog signals representing the same class of signals.", "The processing unit of said on-line module performs selective operations on said incoming analog signals.", "This includes on-line attribute measurements according to the predefined list of attributes, and on-line segmentation according to the range thresholds (i.e. the lower threshold and the higher threshold) received from the control unit.", "The general idea of the operations performed by the processing unit is as follows: (i) perform on-line computation of attribute measurements, until the magnitude of the incoming signal is within said range received from the control unit (detecting the beginning of a segment);", "the computed measurements are called off-segment attribute measurements;", "(ii) perform on-line computation of attribute measurements, until the magnitude of the incoming signal quits said range received from the control (detecting the end of a segment), the computed measurements are called in-segment attribute measurements;", "(iii) send the computed off-segment attribute measurements and in-segment attribute measurements to the control unit, and go to (i).", "It is envisaged that in the practical applications of the invention selected steps of both above-mentioned algorithms can be performed parallelly and/or asynchronously in order to minimize delays and avoid discontinuities in processing the incoming analog signals.", "The off-line module of the preferred embodiment interprets the results received from said on-line module in order to develop a sequential digital profile.", "The off-line module can be a general purpose computing system which has an access to the content of said memory device of the on-line module.", "A single sequential digital profile consists of the following components: (a) a sequence of samples consisting of two values: a lower threshold value and a higher threshold value (the range of a sample);", "(b) a list of attributes divided into two subsets: in-segment attributes and off-segment attributes;", "(c) attribute values of said list of attributes for each sample of said sequence of samples.", "The following analysis is performed to create the abovementioned components of a sequential digital profile: (a) said sequence of samples directly corresponds to said sequence of threshold values;", "(b) said list of attributes is selected from the attributes which can be measured by said processing unit of the on-line module;", "the analysis of off-segment measurements received from the on-line module determines which attributes are to be off-segment attributes of said list of attributes, and the analysis of in-segment measurements received from the on-line module determines which attributes are to be in-segment attributes of said list of attributes;", "human assistance might be required to perform the analysis;", "(c) attribute values for each sample of said sequence of samples are determined through the analysis of off-segment measurements and in-segment measurements received from the on-line module for several incoming analog signals.", "The third module, i.e. the signal generator of random analog signals conforming with a sequential digital profile taken from the off-line module, consists of the following components: (a) a general application computing unit with random-number generating facilities;", "(b) a memory unit;", "(c) a digital-to-analog converter.", "Said computing unit generates a digital signal conforming with said sequential digital profile.", "Said signal is represented by a sequence of numbers randomly generated according to the conditions imposed by said sequential digital profile.", "Said sequence of numbers is stored in the memory unit.", "The digital-to-analog converter converts the content of the memory unit into an analog signal.", "The process of generation of analog signals can be performed either off-line (the whole sequence of numbers is memorized, and then converted to an analog signal) or on-line (each generated number of said sequence of numbers is immediately converted to an analog value) depending on the performances of said computing unit.", "BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein: FIG. 1 is a general block diagram illustrating major components and data flow in a preferred embodiment of the present invention.", "FIG. 2 shows a general structure of the processing unit.", "FIG. 3 shows a general structure Of a sequence of threshold values.", "FIG. 4 is a flowchart illustrating in a broad sense the steps of the algorithm performed in the control unit of the preferred embodiment of the present invention.", "FIG. 5 is a flowchart illustrating in a broad sense the steps of the algorithm performed in the processing unit of the preferred embodiment of the present invention.", "FIG. 6 shows an example of the processing unit which can perform computation of selective attribute measurements.", "FIG. 7 shows an example of a sequence of threshold values according to the general structure of FIG. 3. FIGS. 8 to 11 show examples of incoming analog signals and results of the processing performed by the algorithm of FIG. 4 using processing unit of FIG. 6, and the sequence of threshold values of FIG. 7. FIG. 12 shows a general structure of a sequential digital profile.", "FIG. 13 shows an example of a sequential digital profile obtained from the results shown in FIGS. 8 to 11, according to the general structure of FIG. 12.", "FIG. 14 is a general block diagram of a module generating analog signals conforming with a sequential digital profile.", "FIG. 15 shows examples of analog signals generated by the module of FIG. 14, and conforming with the sequential digital profile of FIG. 13.", "DESCRIPTION OF THE PREFERRED EMBODIMENT In the following description, particular reference is made to the implementation of the invention in the context of processing voltage signals.", "It is envisaged, however, that the practical applications of the invention can be extended to many other areas in which selective physical phenomena would be represented by the analog, time-domain signals.", "Referring to FIG. 1, the preferred system in which the present invention would be applied consists of the on-line module 10 and the off-line module 15.", "The on-line module 10 incorporates the input device 11, the processing unit 12, the control unit 13, and the memory device 14 Incoming analog signals 20 are acquired from the input device 11, which is capable to capture continuously the magnitude of the signals.", "Acquisition of an incoming signal is activated by the signal 21 received from the control unit 13.", "The incoming signal 20 will be denotes as X(t).", "The signal 12 is to inform the control unit that no incoming signal is being received.", "Usually this should suspend or interrupt the control algorithm run by the control unit 13.", "The incoming signal 10 is processed in the processing unit 12 according to the predefined list of attributes 70, and the range 50 (determined by the higher threshold value 51 and the lower threshold value 52) received from the control unit 13.", "This includes extraction of continuous segments of the incoming signal 20 being within the range 50, as well as computation of attribute measurements 30 according to the attributes 70.", "The processing unit 12 is equipped with the devices capable to perform the required computation on-line.", "The computed attribute measurements 30 are sent to the control unit 13.", "The control unit 13 runs a control algorithm, memorizes in the memory device 14 the attribute measurements 30 received from the processing unit 12, and retrieves the sequence of threshold values 23 from said memory device 14.", "The range 50 (i.e. the threshold values 51 and 52) which is being send to processing 12 is extracted from the sequence of threshold values 23.", "The off-line module 15 accumulates the attribute measurements 30 extracted from the memory device 14 in order to create a sequential digital profile 25.", "The off-line module 15 can be also used to load the sequence of threshold values 23 to said memory device 14.", "A sequential digital profile 25 is sent to the signal generator 26 which can generate random analog signals 27 conforming with said sequential digital profile 25.", "Referring to FIG. 2, a general structure of the processing unit 12 comprises the following components: the modules 120 performing on-line computation of attribute measurements 30 for the predetermined list 70 of M attributes {A1, A2, .", ", AM};", "in order to improve on-line performances of the system, each module 120 consists of two identical units 121 and 122;", "the unit 121 performs off-segment measurements 33 while the unit 122 performs in-segment measurements 34;", "the threshold buffers 123 and 124 containing the higher threshold value 51 and the lower threshold value 52 respectively;", "the range selector 125 detecting whether the current magnitude of the incoming signal 20 is within the range defined by the thresholds 51 and 52 received from the buffers 123 and 124 respectively;", "the measurement buffer 130 (consisting of the off-segment buffer 131 and the in-segment buffer 132) memorizing the attribute measurements 30 comprising the off-segment measurements 33 and the in-segment measurements 34, wherein the off-segment attribute measurements 33 are received from the modules 121 and memorized in the buffer 131, while the in-segment attribute measurements 34 are received from the modules 122 and memorized in the buffer 132.", "The reset signals 141 and the load signal 151 are arranged so that the off-segment measurements 33 are computed when the incoming signal 20 is outside the range defined by the thresholds 51 and 52, and said measurements are memorized in the buffer 131 when the incoming signal 20 enters said range.", "The reset signals 142 and the load signal 152 are arranged so that the in-segment measurements 34 are computed when the incoming signal 20 is within the range defined by-the thresholds 51 and 52, and said measurements are memorized in the buffer 132 when the incoming signal 20 quits said range.", "Referring to FIG. 3, the sequence of threshold values 23 stored in the memory device 14 consists of N elements {S1, S2, .", ", SN} wherein each Si incorporates: (i) the higher threshold value HTi (51);", "(ii) the lower threshold value LTi (52).", "Referring to FIG. 4, the algorithm performed in the control unit 13 comprises the following steps: Step 100 Send the signal 21 to initialize acquisition of an incoming analog signal 20 X(t) from the input device 11.", "Step 101 Set i=1.", "Step 102 Retrieve the element Si from the sequence of threshold values 23.", "Step 103 For the retrieved element Si, send the higher threshold value HTi (51) and the lower threshold value LTi (52) to the buffers 123 and 124 of the processing unit 12.", "Step 104 Wait until the off-segment measurements 33 {MeOFA 1 , MeOFA 2 , .", ", MeOFA M } and the in-segment measurements 34 {MeINA 1 , MeINA 2 , .", ", MeINA M } are received from the buffers 131 and 132 of the processing unit 12.", "Step 105 Memorize the off-segment measurements 33 {MeOFA 1 , MeOFA 2 , .", ", MeOFA M } and the in-segment measurements 34 {MeINA 1 , MeINA 2 , .", ", MeINA M } in the memory device 14.", "______________________________________Step 106 If (i <", "N) then i = i + 1;", "goto Step 102elseexit.", "______________________________________ The algorithm can be suspended or terminated at any moment when the signal 22 is received from the processing unit 12, i.e. when no incoming signal 20 is available.", "The abovementioned algorithm is given by way of illustration and example only and is not to be taken by way of limitation, so that in the future embodiments other algorithms 15 based on the same principles could be applied.", "In particular, selected steps of the algorithm can be, .", "performed parallelly, asynchronously or can be pipelined in order to minimize delays and avoid discontinuities in processing the incoming analog signal 20.", "Referring to FIG. 5, the algorithm performed in the processing unit 12 has the following structure: Step 200 Perform on-line computation of off-segment measurements 33 using.", "modules 121 until the magnitude of X(t) is inside the range defined by the content of the threshold buffers 123 and 124.", "Step 201 Memorize said measurements 33 of Step 200 in the measurement buffer 131, and reset the modules 122.", "Step 202 Perform on-line computation of in-segment measurements 34 using modules 122 until the magnitude of X(t) is outside the range defined by the content of the threshold buffers 123 and 124.", "Step 203 Memorize said measurements 34 of Step 202 in the measurement buffer 132, and reset the modules 121.", "Step 204 Goto Step 200.", "FIG. 6 shows a design of a processing unit 12 which can perform attribute measurements for the following list of attributes 70: {A.", "sub[.", "].1 =Period.", "sub.", "-- of.", "sub.", "-- duration, A.sub[.", "].2 =Type.", "sub.", "-- of.", "sub.", "-- monotonicity}.", "The structure of the unit corresponds to the general structure of FIG. 3. The range selector 125 consists of two analog comparators 251 and 252 comparing the incoming signal 20 to the content of the range buffers 123 and 124 respectively.", "The AND-gate 253 provides that the binary output 254 of the range selector 125 is set ONE when the incoming signal 20 is within said range, and ZERO otherwise.", "There are two modules 121 and two corresponding modules 122, i.e. the modules to perform Period -- of -- duration measurements, and the modules to perform Type -- of -- monotonicity measurements.", "The module 121-1 performing Period -- of -- duration measurements consists of the digital counter 211 with the reset signal 141 connected to the ouput 254.", "The clock input of the counter 211 is connected to the external signal generator.", "The module 121-2 performing Type -- of -- monotonicity measurements consists of two flip-flops 214 and 215, which receive signals from the differentiating element 212 through the sign detector 213.", "The small histeresis loop has been added in the sign detector 213 in order to compensate minor variations of the incoming signal 20.", "The flip-flop 214 is set whenever the derivative of the incoming signal 20 is positive, and the flip-flop 215 is set whenever the derivative of the incoming signal 20 is negative.", "The reset signal 141 resets the flip-flops 214 and 215 and closes their Set input AND-gates.", "The modules 122 have the identical structure to the corresponding modules 121.", "The only difference is that the reset signal 142 is connected to the inverted output 254.", "The measurement buffer 131 is a latch register with two inputs connected to flip-flops 214 and 215, and the rest of inputs connected to the counter 211.", "The load signal 151 is connected to the inverted output 254.", "The measurement buffer 132 is similar to the buffer 131.", "The only difference is that the load signal 152 is connected to the output 254.", "Therefore, the attribute measurements 30 (comprising off-segment measurements 33 and in-segment measurements 34) are represented as follows: Off-segment Period -- of -- duration--the corresponding output bits of the buffer 131;", "Off-segment Type -- of -- monotonicity--two output bits of the buffer 131, wherein 01 represents "decreasing";", "10 represents "increasing";", "11 represents "no -- monotonicity";", "In-segment Period -- of -- duration--the corresponding output bits of the buffer 132;", "In-segment Type -- of -- monotonicity--two output bits of the buffer 132, wherein 01 represents "decreasing";", "10 represents "increasing";", "11 represents "no -- monotonicity".", "FIG. 7 shows an example of a sequence of threshold values 23 according to the general structure of FIG. 3 wherein: (i) the sequence of threshold values 23 contains four elements: S1, S2, S3, S4;", "(ii) the threshold values 51 and 52 for the given elements are: ______________________________________ HT.", "sub[.", "].1 = 1.4 LT.", "sub[.", "].1 = 1.0;", "HT.", "sub[.", "].2 = 2.2 LT.", "sub[.", "].2 = 2.0;", "HT.", "sub[.", "].3 = 0.8 LT.", "sub[.", "].3 = 0.4;", "HT.", "sub[.", "].4 = 1.5 LT.", "sub[.", "].4 = 1.2.", "______________________________________ FIGS. 8 to 11 show examples of incoming analog signals 20 being processed by the algorithm of FIG. 4 using processing unit of FIG. 6 and the sequence of threshold values 23 of FIG. 7. The extracted segments 81, 82, 83 and 84 correspond respectively to the elements S1, S2, S3 and S4 from the sequence of threshold values 23.", "The lists 91, 92, 93 and 94 contain the corresponding attribute measurements 33 and 34, wherein: ______________________________________OFA.", "sub[.", "].1 is the off-segment Period.", "sub.", "-- of.", "sub.", "-- duration,OFA.", "sub[.", "].2 is the off-segment Type.", "sub.", "-- of.", "sub.", "-- monotonicity,INA.", "sub[.", "].1 is the in-segment Period.", "sub.", "-- of.", "sub.", "-- duration,INA.", "sub[.", "].2 is the in-segment Type.", "sub.", "-- of.", "sub.", "-- monotonicity,and"-"", "represents "decreasing","+"", "represents "increasing","-/+"", "represents "no.", "sub.", "-- monotonicity".", "______________________________________ Sequential digital profiles 25 would be created using: (i) the sequence of threshold values 23;", "(ii) the predetermined list 70 attributes;", "(iii) the attribute measurements 33 and 34 computed for the given examples of incoming analog signals 20.", "Since the incoming analog signals 20 are supposed to be typical samples of the signals of interest, the corresponding digital profile 25 should be a generalization of the available attributes 70 and the attribute measurements 33 and 34.", "Said generalization might be performed automatically or might require human assistance.", "Referring to FIG. 12, sequential digital profiles 25 consist in general of the following components: (i) the sequence of N samples {S1, S1, .", ", SN} corresponding to the sequence of threshold values 23 stored in the memory device 14, wherein each sample Si (i=1 , .", ", N) has its range 50 bounded by the higher threshold value HTi (51) and the lower threshold value LTi (52);", "(ii) the list of attributes 60 consisting of off-segment attributes 61 {OFA 1 , OFA 2 , .", ", OFA v } and in-segment attributes 62 {INA 1 , INA 2 , .", ", INA w }, wherein both off-segment attributes 61 and in-segment attributes 62 are selected from the predetermined list 70 of M attributes {A1, A2, .", ", AM};", "(iii) for each sample Si(i=1, .", ", n), the sequence of off-segment attribute values 63 {OFA 1 (Si), OFA 2 (Si), .", ", OFA v (Si)};", "(iv) for each sample Si (i=1, .", ", N), the sequence of in-segment attribute values 64 {INA 1 (Si), INA 2 (Si), .", ", INA w (Si)}.", "Therefore, FIG. 13 shows an example of a sequential digital profile 25 obtained from the results given in FIGS. 8 to 11, according to the general structure of FIG. 12.", "Note that the in-segment attributes 62 do not include the Type -- of -- monotonicity attribute.", "This because for this attribute the natural generalization of the results of FIGS. 8 to 11 would give "don't care"", "value for each created sample Si (i=1, .", ", 4).", "The values of the Period -- of -- duration attribute have been rounded with 0.1 sec accuracy.", "The digital profile of FIG. 13 is given by way of illustration and example only and is not to be taken by way of limitation, so that in the future embodiments other methods of generalization based on the same principles could be applied.", "Referring to FIG. 14, a general structure of the signal generator 26 generating random analog signals conforming with a sequential digital profile 25 taken from the off-line module 15, consists of the following components: (i) a general application computing unit 40 incorporating a generator 41 of random numbers;", "(ii) a dual-port memory unit 42;", "(iii) a digital-to-analog converter 43;", "(iv) an output address counter 44 for the memory unit 42.", "The computing unit 40 receives a sequential digital profile 25 from the off-line module 15, and generates a random sequence of numbers 45 which is memorized in the memory unit 42.", "The sequence 45 reappears on the output of the memory unit 42 as a digital signal 46 with a sampling period determined by the dock signal 47 connected to the output address counter 44.", "The digital signal 46 is converted into an output analog signal 27 by the digital-to-analog converter 43.", "The sequence 45 is generated according to the conditions imposed by said sequential digital profile 25.", "For example, for the sequential digital profile 25 of FIG. 13, the first numbers of the corresponding sequence 45 should be in an increasing order, and a number corresponding to some randomly selected moment between 0.2 sec and 1.4 sec should reach the magnitude 1.4.", "The impulse 48 resets the counter 44 and activates the D/A converter 43.", "Therefore, the process of generation of the output analog signal 27 can be performed either on-line or off-line, depending on the performances of the computing unit 40.", "If the computing 40 can generate the sequence 45 with a speed exceeding the frequency of the clock 47, the impulse 48 should appear immediately after the first number of the sequence 45 is memorized into the memory unit 42.", "Otherwise, the impulse 48 should appear after the whole sequence 45 has been memorized into the memory unit 42.", "The output signal 27 is being sent to an external transmit data assembler 28 which includes the signal 27 into an encrypted analog signal 29 either as a front-end-identification signal or as an inserted identification signal.", "front-end-identification signal and/or any identification signal inserted within FIG. 15 shows examples of generated analog signals conforming with the sequential digital profile 25 of FIG. 13.", "The fragments 71, 72, 73 and 74 correspond respectively to the samples S1, S2, S3 and S4 of said sequential digital profile 25 of FIG. 13.", "Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims." ]
BACKGROUND AND SUMMARY OF THE INVENTION This invention is an improvement over my prior U.S. Pat. No. 4,081,012, and over Johnson Pat. No. 2,939,805. In my prior patent, there is disclosed a threaded fastener having fluid, unreacted epoxy resin deposited within thread grooves thereof extending only part way around the fastener, and a fluid activating or polymerizing agent deposited within the thread grooves directly adjacent the epoxy deposit. These two fluid deposits flow together, and where they abut, they react to form a solid barrier film which prevents further reaction until the two fluid materials are intermixed by threading together two mating threaded fasteners, one of which is modified as described above. The prior patent discloses the use of a protective, non-tacky cover film overlying the deposits of fluid epoxy and activator, which is preferably polyvinyl alcohol (PVA), and is applied in an aqueous solution as a spray. Johnson U.S. Pat. No. 2,939,805 discloses and claims a self locking bolt, two component fastening elements having ". . . mutually engageable surfaces . . . " (the threads) and ". . . two discrete mutually polymerizable coatings between said surfaces adapted to be . . . mixed together during engagement of said surfaces to form a polymerized mass effectively locking said surfaces . . . ". The coatings may be deposited by "spraying, dipping and the like" and "are adapted to form a polymerized mixture and when mixed, preferably form a metal-to-metal adhesive." The patent sets out two Examples. In Example 1, an epoxy resin is "heated to a liquid form and a threaded bolt shank is dipped into it to form a single coating." The second superimposed coating is applied only after the liquid epoxy coating has cooled, which is understood to mean that it is changed from its liquid condition to which it was heated to a solid. The second coating is applied by dipping into a solution of a polyamide in methyl isobutyl carbinol. The patent states that a polymeric membrane was substantially immediately formed between the two coatings because they are "mutually reactive". Evidently Johnson's product is completed by evaporation of the solvent, since there is no suggestion that either coating, the epoxy resin or the polyamide solution remain fluid. More significant is the fact that Johnson provides no protective cover material over the coatings. In his second Example, Johnson teaches forming a 70% solids solution of a product formed by reacting 5 mols of totylene diisocyanate with 1 mol of trimethylol propane and 1 mol of 1, 4 hexane diol. The bolt is dipped in this solution and "allowed to dry." The second coating is applied by dipping the bolt in a specific alkyd resin. There is no suggestion that the alkyd resin remains fluid, and the absence of any protective cover indicates that neither of the coating remains fluid or are designed for immediate use. In my prior U.S. Pat. No. 4,081,012, I have disclosed the deposit of a fluid epoxy resin and a fluid activator circumferentially in contiguous areas. Where these materials come into contact with each other, there is formed a barrier film which prevents intermixture of these deposits until the fasteners are brought together. To protect these deposits, at least one of which remains fluid, a thin protective cover film, specifically PVA, is applied. In accordance with the present invention, a new product in the form of a threaded fastener having in an annular zone extending completely around the fastener, superimposed deposits both of which also extend completely around the fastener and which react to form an annular barrier film extending between the deposits to prevent intermixture thereof. The deposits, which remain fluid, have a non-tacky protective cover film over the deposits. The production of these fateners is accomplished on a single, short production line, in which a succession of bolts are advanced on a conveyor through stations which apply a deposit of at least partly unreacted fluid epoxy resin, a deposit of fluid activator, a deposit of a film-forming aqueous solution of protective material such as PVA, and an application of a quick drying powder such as guar to the film forming material. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary elevation of a fastener in accordance with the present invention. FIG. 2 is an enlarged sectional view of a portion of a thread. FIG. 3 is a diagrammatic view of the production line. FIG. 4 is a plan view of a special spinner disk to apply activator to the previously applied epoxy resin. FIG. 5 is a sectional view on the line 3--3, in FIG. 2. DETAILED DESCRIPTION The present invention provides a fully automatic, high production, inexpensive method of producing threaded fasteners provided with locking means activated only by threaded engagement with a mating fastener, and a novel fastener produced by the method. The fastener, herein illustrated as a male fastener element or bolt 10, a portion of which is illustrated in FIG. 1, has on an intermediate portion thereof, a complete annular ring or band 12 in which locking material is deposited within the thread grooves. The band 12 is spaced from the entering end 14 of the fastener, to facilitate initiation of threaded engagement with a mating fastener element. Within the band or ring 12, as best seen in the enlarged sectional view of FIG. 2, there is deposited within the bottom of the thread grooves 16 a fluid polymerizable resin 18. A preferred resin for this purpose is an epoxy resin which is deposited and which remains in a fluid condition until it is polymerized as will be subsequently described. As seen in this Figure, the deposit 18 extends along the sides of the thread grooves nearly or completely to the top thereof, but is supplied in such an amount that it does not fill the groove. Its outer surface assumes the concave curvature illustrated. Overlying the resin completely around the fastener is a continuous layer 20 of an activator to effect polymerization of the resin, when mixed therewith. The layer 20, as will later be described, is applied in such a way that it does not mix with the resin. However, where the inner surface of the layer 20 comes into contact with the outer surface of the resin deposit, there is an immediate interaction which produces a barrier film. The barrier film prevents or limits the interaction, so that there is provided a still fluid resin deposit 18, a solid barrier film indicated by the line 22, and a still fluid, relatively thin layer 20 of the activator or polymerization agent. The quantity of polymerizable resin and activator is preferably such that together they substantially fill the thread groove as seen in FIG. 2, but leave the material as so far deposited wholly within the thread groove as illustrated. The fastener is then provided with a thin coating of a protective film-forming material which preferably is an aqueous solution of polyvinyl alcohol. In order to expedite formation of the film 23, the exposed PVA solution is subjected to a spray of powdered desiccant which extracts water from the PVA solution, providing some interim strength to the film and supplying partial protection to the resin and activator deposits while final drying proceeds. Excellent results have been obtained in commercial production when the powdered desiccant is a derivative of guar gum identified by the supplier (Celanese Plastics and Specialties Co., Louisville, Ky.) as HP-11. Evidently the powder remains in expanded but still granular form and has the effect of forming a rough exposed surface for the bonding material. This has a practical advantage in that it facilitates break-up of the PVA film when threaded fasteners are engaged, and assists in mixing the resin and hardener. It is usual for the customer to specify a minimum torque required to separate threaded fasteners locked or bonded together by the bonding material. In some cases the specified break-away torque is at a value which in the past has been difficult to achieve. It has been found that the inclusion, usually in the resin, of hard abrasive particles, increases the effectiveness of the locking action so that even exceptionally high torque requirements are easily surpassed. The addition of ordinary table salt crystals has proved entirely satisfactory. The exact co-action of the salt crystals in the combination disclosed is not clear, but it is assumed that the improved results are attributable to a scouring of the fluid resin from the threaded surfaces and a better and more intimate mixing of the resin and activator. In some cases, the effectiveness of the locking action so far exceeds th minimum specified break-away torque that it is desirable to decrease the torque. This may be accomplished by adding a mixture of salt crystals and particles of previously cured resin, such as nylon, teflon, or the like, or by substituting such particles for the crystals. Another factor has to be taken into account in formulating the resin mixture. The method of production is carried out at room temperature, or at least with only moderate heating to accelerate reactions. This in turn requires that the resin mixture as applied have a suitable fluidity at the prevailing temperature. It is desired to have the resin flow within a thread groove and to a limited extent along the thread groove so as to form a deposit which, within each thread groove in the band or ring, is of uniform cross-section. The addition of salt crystals, discrete particles of resin, or both, affects not only the break-away torque in a completed thread bond, but also the fluidity of the resin mixture as initially deposited. Another factor is of course the temperature of the resin, whose fluidity or viscosity is variable in accordance with temperature. While the entire process is carried out at or about room temperature, it is contemplated that the resin mixture may be supplied at an elevated temperature which produces the desired fluidity or viscosity. From the foregoing it will be apparent that the selection and amount of additions to the resin must be for the most part empirical. In use, the mating threaded fastening elements are threaded together, and the interference between the deposits in the thread grooves of one element and the threads of the other ruptures and breaks up to the protective film overlying the deposit. In addition, the barrier film between the resin and activator is ruptured and broken up. The resin and activator are intermixed by the motion between opposed thread surfaces, enhanced as required by the included abrasive and/or discrete resin particles, and the resin is cured or polymerized to form a thread lock preventing undesired separation between the fastener elements. The fastener itself is novel in the provision of a fluid unpolymerized or at least not completely polymerized resin and a fluid activator therefor selected to cause prompt polymerization thereof when mixed. This is further true because of the addition of the particulate matter, abrasive crystals such as salt or discrete solid resin particles such as nylon, teflon, or the like. These particles, in the fluid mixture of resin and activator, ensure thorough mixing, quick setting, and a controllable bonding action tailored to fit the required break-away torque range required. Production Method The product has been designed to provide for quantity production by fully automatic equipment. Referring now to FIG. 3, there is shown a production line in which a pair of spaced horizontally extending belts 30 are provided and driven by rolls, one of which is seen at 32. The headed fasteners are supported on the belts by their heads and the threaded shanks extend downwardly between the belts. At a first station, designated generally at A, the heads of the bolts are engaged between a pair of rotating rollers, one of which is seen at 34, provided with soft resilient tires which grip the bolt heads and rotate them positively to ensure uniform treatment around the circumference of the bolt shank. The speed of rotation of the rolls is related such that the bolts traverse station A at a desired rate. Means are provided at station A to deposit within the thread grooves 16 throughout the annular band 12 a fluid polymerizable resin, with particulate material mixed therein as desired. This deposition means is diagrammatically shown at 36, and may be in the form of a spray, an extruder or an applicator wheel operated to provide a uniform deposit 18 of the fluid resin within the thread grooves throughout the band 12. The fasteners are advanced to station B where a layer or ply 20 of activator or hardener for the resin is deposited uniformly to overlie the resin. The means for depositing the activator is illustrated diagrammatically in FIG. 1 at 38. Excellent results in applying this layer have been obtained by feeding the fluid activator to a disk 40, as seen in FIGS. 4 and 5. This disk is rotated about a vertical axis to fling the activator fluid centrifugally onto the resin deposit. The periphery of the disk is slotted radially and some of the resulting tangs 42 are bent upwardly as indicated at U, some are bent downwardly as indicated at D, and the rest allowed to remain flat as indicated at F. This provides a simple structure for supply the fluid activator to a band of selected width as determined by the displacement of the tangs. Disks 40 are of course contained in a housing and the fluid activator not deposited on the bolts is collected for reuse. At station B, the fasteners are also rotated by rotating soft tired wheels or rollers 34. The fasteners with the fluid resin deposits 18 and the activator deposits 20, are now advanced by belts 30 through station C where an aqueous solution of PVA is sprayed to completely cover the activator deposit. The spray for the PVA solution is indicated diagrammatically at 46. In order that the entire production of the treated fasteners disclosed herein may be fully automatic and require only a relatively short production line, a fourth station D is provided, at which the powdered desiccant is applied to the PVA solution by means diagrammatically illustrated at 48. In practice, the bolt shanks at station D may be substantially enclosed to prevent loss of desiccant. Again, the fasteners are preferably rotated about their axes, as in all previous stations, by the rotating rollers 34. The treatment of the film-forming deposit of PVA solution with the desiccant powder permits the finished fasteners to be collected at the end of the production line in containers 50. Since the fasteners may be supplied to the belts 30 by a conventional feeder, it will be apparent that the entire operation is automatic, thus providing for economical high production of the treated fasteners. While the entire operation is essentially at room temperature, it is apparent that if required drying means such as radiant heaters indicated at 52 may be provided either beyond the desiccant supply means 52, or between this and the PVA supply means 48. Related Applications Attention is called to my co-pending applications, which disclose some of the features included in the present invention as follows: Ser. No. 376,764, now U.S. Pat. No. 4,428,981, Method and Apparatus for Making Friction Locking Threaded Fasteners. This application discloses soft tired rotating wheels engageable with the heads of bolts suspended between parallel belts to provide positive rotation as thermoplastic particles are deposited in an annular zone on the threaded shanks, which are heated to a temperature to fuse the particles. Ser. No. 379,110, Thread Lock. This application discloses the use of a desiccant powder such as guar to harden protective film from a coating of an aqueous solution of PVA over circumferentially contiguous deposits of fluid epoxy resin and a fluid activator therefor. While the exact composition of the deposits of fluid resin and abrasive and discrete resin particles is necessarily empirical, a specific example of one such mixture is set forth below: ______________________________________ Volume Units______________________________________Uncured fluid epoxy resin 4000 ML(sold by Hardman Corp. andidentified by them as13050 A)Common table salt crystals 900 MLNylon particles 100 ML 100%______________________________________ The activator used to form a layer over the deposit of resin mixture is a tertiary amine sold by Synthron Corporation and identified by them as NX-3. The aqueous solution of PVA is an 8-10% solution. When applied as described to a 1/2" stud and cured after engaged in a threaded opening, the break-away torque is about 800-1000 in/lb.
A threaded fastener having a deposit of a fluid polymerizable resin in the bottoms of the thread grooves, a fluid polymerizing agent overlying the resin in the thread grooves, and a strong non-tacky protective film covering the agent. The fluid resin and agent have therebetween a barrier film as a result of polymerization of the resin where it contacts the polymerizing agent. Preferably, the fluid resin and agent deposit includes abrasive particles, such as table salt to enhance mixing when the fastener engages a mating threaded member. In production, the protective film is applied as an aqueous solution of PVA, which is rapidly converted to the non-tacky film by the application of a desiccant powder such as a derivative of guar gum.
Briefly summarize the invention's components and working principles as described in the document.
[ "BACKGROUND AND SUMMARY OF THE INVENTION This invention is an improvement over my prior U.S. Pat. No. 4,081,012, and over Johnson Pat. No. 2,939,805.", "In my prior patent, there is disclosed a threaded fastener having fluid, unreacted epoxy resin deposited within thread grooves thereof extending only part way around the fastener, and a fluid activating or polymerizing agent deposited within the thread grooves directly adjacent the epoxy deposit.", "These two fluid deposits flow together, and where they abut, they react to form a solid barrier film which prevents further reaction until the two fluid materials are intermixed by threading together two mating threaded fasteners, one of which is modified as described above.", "The prior patent discloses the use of a protective, non-tacky cover film overlying the deposits of fluid epoxy and activator, which is preferably polyvinyl alcohol (PVA), and is applied in an aqueous solution as a spray.", "Johnson U.S. Pat. No. 2,939,805 discloses and claims a self locking bolt, two component fastening elements having ".", "mutually engageable surfaces .", """, "(the threads) and ".", "two discrete mutually polymerizable coatings between said surfaces adapted to be .", "mixed together during engagement of said surfaces to form a polymerized mass effectively locking said surfaces .", "".", "The coatings may be deposited by "spraying, dipping and the like"", "and "are adapted to form a polymerized mixture and when mixed, preferably form a metal-to-metal adhesive.", """, "The patent sets out two Examples.", "In Example 1, an epoxy resin is "heated to a liquid form and a threaded bolt shank is dipped into it to form a single coating.", """, "The second superimposed coating is applied only after the liquid epoxy coating has cooled, which is understood to mean that it is changed from its liquid condition to which it was heated to a solid.", "The second coating is applied by dipping into a solution of a polyamide in methyl isobutyl carbinol.", "The patent states that a polymeric membrane was substantially immediately formed between the two coatings because they are "mutually reactive".", "Evidently Johnson's product is completed by evaporation of the solvent, since there is no suggestion that either coating, the epoxy resin or the polyamide solution remain fluid.", "More significant is the fact that Johnson provides no protective cover material over the coatings.", "In his second Example, Johnson teaches forming a 70% solids solution of a product formed by reacting 5 mols of totylene diisocyanate with 1 mol of trimethylol propane and 1 mol of 1, 4 hexane diol.", "The bolt is dipped in this solution and "allowed to dry.", """, "The second coating is applied by dipping the bolt in a specific alkyd resin.", "There is no suggestion that the alkyd resin remains fluid, and the absence of any protective cover indicates that neither of the coating remains fluid or are designed for immediate use.", "In my prior U.S. Pat. No. 4,081,012, I have disclosed the deposit of a fluid epoxy resin and a fluid activator circumferentially in contiguous areas.", "Where these materials come into contact with each other, there is formed a barrier film which prevents intermixture of these deposits until the fasteners are brought together.", "To protect these deposits, at least one of which remains fluid, a thin protective cover film, specifically PVA, is applied.", "In accordance with the present invention, a new product in the form of a threaded fastener having in an annular zone extending completely around the fastener, superimposed deposits both of which also extend completely around the fastener and which react to form an annular barrier film extending between the deposits to prevent intermixture thereof.", "The deposits, which remain fluid, have a non-tacky protective cover film over the deposits.", "The production of these fateners is accomplished on a single, short production line, in which a succession of bolts are advanced on a conveyor through stations which apply a deposit of at least partly unreacted fluid epoxy resin, a deposit of fluid activator, a deposit of a film-forming aqueous solution of protective material such as PVA, and an application of a quick drying powder such as guar to the film forming material.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary elevation of a fastener in accordance with the present invention.", "FIG. 2 is an enlarged sectional view of a portion of a thread.", "FIG. 3 is a diagrammatic view of the production line.", "FIG. 4 is a plan view of a special spinner disk to apply activator to the previously applied epoxy resin.", "FIG. 5 is a sectional view on the line 3--3, in FIG. 2. DETAILED DESCRIPTION The present invention provides a fully automatic, high production, inexpensive method of producing threaded fasteners provided with locking means activated only by threaded engagement with a mating fastener, and a novel fastener produced by the method.", "The fastener, herein illustrated as a male fastener element or bolt 10, a portion of which is illustrated in FIG. 1, has on an intermediate portion thereof, a complete annular ring or band 12 in which locking material is deposited within the thread grooves.", "The band 12 is spaced from the entering end 14 of the fastener, to facilitate initiation of threaded engagement with a mating fastener element.", "Within the band or ring 12, as best seen in the enlarged sectional view of FIG. 2, there is deposited within the bottom of the thread grooves 16 a fluid polymerizable resin 18.", "A preferred resin for this purpose is an epoxy resin which is deposited and which remains in a fluid condition until it is polymerized as will be subsequently described.", "As seen in this Figure, the deposit 18 extends along the sides of the thread grooves nearly or completely to the top thereof, but is supplied in such an amount that it does not fill the groove.", "Its outer surface assumes the concave curvature illustrated.", "Overlying the resin completely around the fastener is a continuous layer 20 of an activator to effect polymerization of the resin, when mixed therewith.", "The layer 20, as will later be described, is applied in such a way that it does not mix with the resin.", "However, where the inner surface of the layer 20 comes into contact with the outer surface of the resin deposit, there is an immediate interaction which produces a barrier film.", "The barrier film prevents or limits the interaction, so that there is provided a still fluid resin deposit 18, a solid barrier film indicated by the line 22, and a still fluid, relatively thin layer 20 of the activator or polymerization agent.", "The quantity of polymerizable resin and activator is preferably such that together they substantially fill the thread groove as seen in FIG. 2, but leave the material as so far deposited wholly within the thread groove as illustrated.", "The fastener is then provided with a thin coating of a protective film-forming material which preferably is an aqueous solution of polyvinyl alcohol.", "In order to expedite formation of the film 23, the exposed PVA solution is subjected to a spray of powdered desiccant which extracts water from the PVA solution, providing some interim strength to the film and supplying partial protection to the resin and activator deposits while final drying proceeds.", "Excellent results have been obtained in commercial production when the powdered desiccant is a derivative of guar gum identified by the supplier (Celanese Plastics and Specialties Co., Louisville, Ky.) as HP-11.", "Evidently the powder remains in expanded but still granular form and has the effect of forming a rough exposed surface for the bonding material.", "This has a practical advantage in that it facilitates break-up of the PVA film when threaded fasteners are engaged, and assists in mixing the resin and hardener.", "It is usual for the customer to specify a minimum torque required to separate threaded fasteners locked or bonded together by the bonding material.", "In some cases the specified break-away torque is at a value which in the past has been difficult to achieve.", "It has been found that the inclusion, usually in the resin, of hard abrasive particles, increases the effectiveness of the locking action so that even exceptionally high torque requirements are easily surpassed.", "The addition of ordinary table salt crystals has proved entirely satisfactory.", "The exact co-action of the salt crystals in the combination disclosed is not clear, but it is assumed that the improved results are attributable to a scouring of the fluid resin from the threaded surfaces and a better and more intimate mixing of the resin and activator.", "In some cases, the effectiveness of the locking action so far exceeds th minimum specified break-away torque that it is desirable to decrease the torque.", "This may be accomplished by adding a mixture of salt crystals and particles of previously cured resin, such as nylon, teflon, or the like, or by substituting such particles for the crystals.", "Another factor has to be taken into account in formulating the resin mixture.", "The method of production is carried out at room temperature, or at least with only moderate heating to accelerate reactions.", "This in turn requires that the resin mixture as applied have a suitable fluidity at the prevailing temperature.", "It is desired to have the resin flow within a thread groove and to a limited extent along the thread groove so as to form a deposit which, within each thread groove in the band or ring, is of uniform cross-section.", "The addition of salt crystals, discrete particles of resin, or both, affects not only the break-away torque in a completed thread bond, but also the fluidity of the resin mixture as initially deposited.", "Another factor is of course the temperature of the resin, whose fluidity or viscosity is variable in accordance with temperature.", "While the entire process is carried out at or about room temperature, it is contemplated that the resin mixture may be supplied at an elevated temperature which produces the desired fluidity or viscosity.", "From the foregoing it will be apparent that the selection and amount of additions to the resin must be for the most part empirical.", "In use, the mating threaded fastening elements are threaded together, and the interference between the deposits in the thread grooves of one element and the threads of the other ruptures and breaks up to the protective film overlying the deposit.", "In addition, the barrier film between the resin and activator is ruptured and broken up.", "The resin and activator are intermixed by the motion between opposed thread surfaces, enhanced as required by the included abrasive and/or discrete resin particles, and the resin is cured or polymerized to form a thread lock preventing undesired separation between the fastener elements.", "The fastener itself is novel in the provision of a fluid unpolymerized or at least not completely polymerized resin and a fluid activator therefor selected to cause prompt polymerization thereof when mixed.", "This is further true because of the addition of the particulate matter, abrasive crystals such as salt or discrete solid resin particles such as nylon, teflon, or the like.", "These particles, in the fluid mixture of resin and activator, ensure thorough mixing, quick setting, and a controllable bonding action tailored to fit the required break-away torque range required.", "Production Method The product has been designed to provide for quantity production by fully automatic equipment.", "Referring now to FIG. 3, there is shown a production line in which a pair of spaced horizontally extending belts 30 are provided and driven by rolls, one of which is seen at 32.", "The headed fasteners are supported on the belts by their heads and the threaded shanks extend downwardly between the belts.", "At a first station, designated generally at A, the heads of the bolts are engaged between a pair of rotating rollers, one of which is seen at 34, provided with soft resilient tires which grip the bolt heads and rotate them positively to ensure uniform treatment around the circumference of the bolt shank.", "The speed of rotation of the rolls is related such that the bolts traverse station A at a desired rate.", "Means are provided at station A to deposit within the thread grooves 16 throughout the annular band 12 a fluid polymerizable resin, with particulate material mixed therein as desired.", "This deposition means is diagrammatically shown at 36, and may be in the form of a spray, an extruder or an applicator wheel operated to provide a uniform deposit 18 of the fluid resin within the thread grooves throughout the band 12.", "The fasteners are advanced to station B where a layer or ply 20 of activator or hardener for the resin is deposited uniformly to overlie the resin.", "The means for depositing the activator is illustrated diagrammatically in FIG. 1 at 38.", "Excellent results in applying this layer have been obtained by feeding the fluid activator to a disk 40, as seen in FIGS. 4 and 5.", "This disk is rotated about a vertical axis to fling the activator fluid centrifugally onto the resin deposit.", "The periphery of the disk is slotted radially and some of the resulting tangs 42 are bent upwardly as indicated at U, some are bent downwardly as indicated at D, and the rest allowed to remain flat as indicated at F. This provides a simple structure for supply the fluid activator to a band of selected width as determined by the displacement of the tangs.", "Disks 40 are of course contained in a housing and the fluid activator not deposited on the bolts is collected for reuse.", "At station B, the fasteners are also rotated by rotating soft tired wheels or rollers 34.", "The fasteners with the fluid resin deposits 18 and the activator deposits 20, are now advanced by belts 30 through station C where an aqueous solution of PVA is sprayed to completely cover the activator deposit.", "The spray for the PVA solution is indicated diagrammatically at 46.", "In order that the entire production of the treated fasteners disclosed herein may be fully automatic and require only a relatively short production line, a fourth station D is provided, at which the powdered desiccant is applied to the PVA solution by means diagrammatically illustrated at 48.", "In practice, the bolt shanks at station D may be substantially enclosed to prevent loss of desiccant.", "Again, the fasteners are preferably rotated about their axes, as in all previous stations, by the rotating rollers 34.", "The treatment of the film-forming deposit of PVA solution with the desiccant powder permits the finished fasteners to be collected at the end of the production line in containers 50.", "Since the fasteners may be supplied to the belts 30 by a conventional feeder, it will be apparent that the entire operation is automatic, thus providing for economical high production of the treated fasteners.", "While the entire operation is essentially at room temperature, it is apparent that if required drying means such as radiant heaters indicated at 52 may be provided either beyond the desiccant supply means 52, or between this and the PVA supply means 48.", "Related Applications Attention is called to my co-pending applications, which disclose some of the features included in the present invention as follows: Ser.", "No. 376,764, now U.S. Pat. No. 4,428,981, Method and Apparatus for Making Friction Locking Threaded Fasteners.", "This application discloses soft tired rotating wheels engageable with the heads of bolts suspended between parallel belts to provide positive rotation as thermoplastic particles are deposited in an annular zone on the threaded shanks, which are heated to a temperature to fuse the particles.", "Ser.", "No. 379,110, Thread Lock.", "This application discloses the use of a desiccant powder such as guar to harden protective film from a coating of an aqueous solution of PVA over circumferentially contiguous deposits of fluid epoxy resin and a fluid activator therefor.", "While the exact composition of the deposits of fluid resin and abrasive and discrete resin particles is necessarily empirical, a specific example of one such mixture is set forth below: ______________________________________ Volume Units______________________________________Uncured fluid epoxy resin 4000 ML(sold by Hardman Corp.", "andidentified by them as13050 A)Common table salt crystals 900 MLNylon particles 100 ML 100%______________________________________ The activator used to form a layer over the deposit of resin mixture is a tertiary amine sold by Synthron Corporation and identified by them as NX-3.", "The aqueous solution of PVA is an 8-10% solution.", "When applied as described to a 1/2"", "stud and cured after engaged in a threaded opening, the break-away torque is about 800-1000 in/lb." ]
CROSS-REFERENCE TO RELATED APPLICATIONS This application is a National Phase Application of PCT International Application No. PCT/PT2010/000061, International Filing Date Dec. 9, 2010, claiming priority of Portuguese Patent Application No. 105190, filed Jul. 8, 2010, which is hereby incorporated by reference. FIELD OF THE INVENTION This invention discloses a photonic system and method with the purpose of beamforming the electric field yield by a phased array antenna (PAA). The system relies on a photonic tunable optical delay line (TODL), which is an Mach-Zehnder optical interferometer with a predefined differential time delay between arms. The time delay is tuned by adjusting the coupling ratio between the power applied to each one of the interferometer's delay lines. Three embodiments are proposed, wherein one of them just uses a single delay line and a single monochromatic light (ML) source, independently of the quantity of elementary antennas of the phased array. The application of the described TODL in a photonic system with the purpose of beamforming the electric field yield by a PAA has not been found in the present state of the art. The proposed system is appropriate to wireless communication systems with high frequency RF carriers, which allow handling with high data transmission rates. The proposed invention presents a novel approach in beamforming systems for the electric field radiated by a PAA. PAA's are being increasingly used, because such antennas allow directing the radiated beam precisely to any target direction, without using any mechanical displacement. Since the bandwidth of data transmission is growing in wired or wireless communication systems, interconnecting systems between both these types of communication systems are required, which allow high data transmission rates. Let us consider the following example: a wireless network system with high data transmission rates (≦1 Gb/s) can use a radio over fiber (RoF) system to connect a central office to a remote PAA. Subsequently, the PAA will direct the beam in a target direction using the proposed system, since it allows the acceptance of high data transmission rates. Another area of interest outside communication systems is radio astronomy, which requires advanced antenna technology to monitor signals arriving from outer space with low power and high bandwidths. In comparison with the photonic beamforming techniques reported so far, the proposed system is rather simple and is based on a well-known optics device, the Mach-Zehnder delay interferometer (MZDI). Its implementation is made with commercially available components. It also allows a very fast beam tuning, particularly when its implementation uses integrated optics. According to its inventors point of view, the main advantage is that it just requires one optical delay line (the birefringent medium in the embodiment shown in FIG. 3 ) and a single ML source, independently of the quantity of elementary antennas. This feature was not found in any techniques reported in prior art's literature. BACKGROUND ART DESCRIPTION A PAA comprises N antennas disposed along the three spatial dimensions. The antennas which form the PAA are known as elementary antennas. A PAA allows the optimization and the beamforming of the radiated electrical field through the adjustment of the amplitude and phase of the radio frequency (RF) signals sent to each elementary antenna. This is an exclusive feature for the PAA's, since in an individual antenna the optimization of the radiated electrical field depends on the antenna's design. In addition, the beamforming of the radiated electrical field depends on the spatial orientation of the antenna. As previously said, the beamforming of the electrical field radiated by the PAA can be controlled through the phase of the RF signals applied to each elementary antenna. More precisely, the PAA can be fed by a single RF signal, which is split to all elementary antennas including a tunable phase shift. Although tunable, the phase shift is constant. This means the induced phase shift value is correct only for a specific RF frequency. In a PAA, this implies that the emitted frequency should be constant. Otherwise, different RF frequencies get different phase shifts, and so the beamforming of the electric field becomes dependent on the emitted frequency. In the case of data transmission over one RF carrier frequency, this implies that the data signal bandwidth should be as low as possible. Since there are many applications with high bandwidth (e.g., RADAR signals, Gb/s wireless networks, radio astronomy, etc.), the beamforming of the radiated electric field cannot be efficiently performed with such a technique. This problem can be solved using phase shifts that depend on RF frequency. In practice, a phase shift depending on frequency consists in a time delay line. Therefore, instead of a phase shift, each elementary antenna should include a tunable time delay. The electrical implementation of a tunable time delay is particularly challenging at high frequencies, since increasing time delays implies increasing the length of the delay line, which in turn leads to greater insertion losses and a reduction in bandwidth. Such disadvantages are overcome using photonic implementations of tunable delay lines. The advantages of photonic systems consist on low losses, broad bandwidth, lighter weights, smaller dimensions and immunity to electromagnetic interference. Generally, a PAA with tunable photonic delay lines is characterized in that it has an electro-optical modulator, which converts the RF signal to the optical domain, followed by an optical processing system which delays and distributes the modulated optical signal according to what the needs of the different antennas are. The optical signals are converted to the electrical domain using photodetectors. The patents summarized below describe different implementations of photonic TODL's, which can be applied to PAA. U.S. Pat. No. 5,428,218 discloses a photonic TODL based on spatial multiplexing. In such free-space implementation, the optical signal is directed into a given optical fiber through the adjustment of mirrors. As different optical fibers have different lengths, one can get a discrete tuning of the time delay added to the optical signal. This implementation also includes the possibility of having a multi-beam system, e.g., the system can be simultaneously used by more than one optical signal. U.S. Pat. No. 5,978,125 discloses a photonic TODL based on polarization multiplexing. In a birefringent medium, an optical signal with a specific state-of-polarization (SOP) has a higher time delay than the orthogonal SOP. By selecting one of the two SOP's, the added time delay can then be controlled. This method is described in a cascaded configuration, in which serial birefringent media are intercalated by polarization controllers (PC's). As a result, a discrete delay tuning is obtained. U.S. Pat. No. 5,461,687 discloses a photonic TODL based on dispersive means. By tuning the wavelength of the input optical signal the path by which the signal propagates changes, resulting in a tunable time delay. In this patent, the dispersive mean is implemented in a free space using a diffraction grating. Another possible option is to use fiber Bragg gratings (FBG's) located in different points of an optical fiber. U.S. Pat. No. 5,751,466 discloses a photonic TODL which uses the frequency response of a photonic bandgap device. An example of such a device is a FBG. This device consists of a dielectric structure in which the refractive index varies longitudinally. The control of the refractive index's variation along the structure results in changing the frequency response of the device, therefore affecting the time delay added to the photonic signal. U.S. Pat. No. 7,558,450 B2 discloses a photonic TODL composed by three resonant elements coupled to a waveguide. This implementation is limited to single sideband (SSB) optical signals. The symmetric displacement in the frequency of two resonant elements enables the adjustment of time delay induced to the RF carrier. The third resonant element adjusts the phase of the optical carrier (OC) in order to avoid involuntary phase shifting of RF signal. Of greater importance than the tuning method, is the fact that this patent is clearly appropriate to RF signals without any spectral content between the optical and the RF carriers. As a result, the TODL's frequency response is irrelevant at frequencies located between the RF carrier and the OC. BRIEF DESCRIPTION OF THE DRAWINGS The following description is based on the drawings attached hereto, which are represented without any restrictions: In FIG. 1 the response in amplitude and the photonic TODL group delay, considering different coupling ratios α among the power applied to each one of the interferometer's optical delay lines. FIG. 2 shows a first embodiment of the invention; FIG. 3 shows a second embodiment of the invention; and FIG. 4 shows a third embodiment of the invention. FIG. 5 shows a fourth embodiment of the invention. FIG. 6 shows a fifth embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION The system proposed for beamforming the electric field yield by a PAA can be divided in three subsystems. In the first subsystem, the RF signal modulates a monochromatic optical carrier. The resulting modulated optical signal is split into N copies, where N is the number of elementary antennas. Each copy is introduced into a TODL, and then reconverted to the electrical domain by means of a photodetector. Each photodetector is connected to the respective elementary antenna. The key element of a beamforming system is the tunable delay line, because generally a PAA with N antennas requires N tunable delay lines. The proposed TODL consists of a MZDI with two arms. The MZDI is composed of an input optical coupler to which two delay lines and an output coupler which adds the signals coming from both lines. The delay lines have a fixed time delay difference τ. One of the optical couplers has a tunable coupling ratio, i.e., the optical power ratio in the two delay lines can be tuned. According to what is claimed in patent PT 104237, the proposed MZDI consists of an optical filter with tunable response, which approximately corresponds to a weighted average of the delay lines responses. The tuning is carried out through the adjustment of the optical power ratio between the two delay lines. As a result, a desired TODL with a tuning ranging from 0 to τ is obtained. In terms of a mathematic expression, the frequency response of the MZDI is given by H ⁡ ( f ) = 2 2 ⁡ [ α + 1 - α 2 ⁢ ⅇ - j2π ⁢ ⁢ f ⁢ ⁢ τ ] , ( 1 ) where 0≦α≦1 is the coupling ratio and f is the frequency. The amplitude response ∥H(f)∥ 2 and the group delay τ(f) can be derived from ( 1 ),  H ⁡ ( f )  2 = 1 2 ⁢ { 1 + 2 ⁢ α ⁢ 1 - α 2 ⁢ cos ⁡ ( 2 ⁢ π ⁢ ⁢ f ⁢ ⁢ τ ) } , ( 2.1 ) τ ⁡ ( f ) = τ ⁢ { 1 - α 2 + α ⁢ 1 - α 2 ⁢ cos ⁡ ( 2 ⁢ π ⁢ ⁢ f ⁢ ⁢ τ ) 1 + 2 ⁢ α ⁢ 1 - α 2 ⁢ cos ⁡ ( 2 ⁢ π ⁢ ⁢ f ⁢ ⁢ τ ) } . ( 2.2 ) Both derived equations show that the TODL has a periodic frequency response with a period 1/τ. The amplitude response and the group delay are depicted in FIG. 1 for different values of α. As predicted by ( 2 . 1 ) and ( 2 . 2 ), both the amplitude response and the group delay are affected by α. As a result, the optical signal must be properly centered with the MZDI's frequency response. The absolute value of the amplitude response can be adjusted by means of variable optical attenuators (VOA's), located at the input or output of the TODL's, or using electrical amplifiers for the signals detected. Generally, a RF signal modulated over an OC has three spectral lines located at f 0 −f RF , f 0 and f 0 +f RF , where f 0 is the OC frequency and f RF is the frequency of the RF signal. In the case of data transmission, copies of the transmitted sequence spectrum are centered at the three spectral lines. Thus, there are two ways for centering the modulated signal spectrum with the MZDI's frequency response. The first one consists of setting all the three spectral lines within a single period of the MZDI's response. The other way makes use of the fact that the TODL's frequency response is irrelevant to frequencies located between the RF carriers and the OC. Each one of the spectral lines is then centered at different maxima of the MZDI's amplitude response. The implementation of the proposed photonic system for beamforming the electric field radiated by a PAA is presented through five different architectures. Proposed Embodiments The first proposed embodiment is shown in FIG. 2 . This embodiment comprises a ML source ( 1 ), optical connections ( 2 ), ( 6 ), ( 8 ), an electro-optic modulator ( 4 ), a 1 to N optical signal splitter ( 5 ), N TODL's based on the proposed MZDI ( 7 ), N photodetectors ( 9 ) and N elementary antennas ( 10 ). By means of an electro-optic modulator ( 4 ), the monochromatic signal generated by the light source ( 1 ) is modulated by the electric RF signal ( 3 ) which will be radiated by the PAA. The modulated optical signal is split into N copies using a 1 to N optical splitter ( 6 ). Each one of the N copies is input into a TODL ( 7 ), which consists of a MZDI ( 7 ) with two arms and tunable coupling ratio. Each arm of the MZDI is a fixed optical delay line, where the propagation time difference of both arms is T. The time delay added to each copy of the modulated signal, before such copy enters its TODL ( 7 ), can be predefined by the length of the optical connections ( 6 ). After being time delayed, each copy is converted to the electrical domain using a photodetector ( 9 ) and subsequently sent to the respective elementary antenna ( 10 ). Briefly, the direction of the radiated electrical field is defined by manipulating the coupling ratios for the N TODL's ( 7 ). The second embodiment is shown in FIG. 3 . This embodiment also comprises a ML source ( 1 ), optical connections ( 2 ), ( 6 ), ( 8 ), an electro-optic modulator ( 4 ), a 1 to N optical signal splitter ( 5 ), N photodetectors ( 9 ) and N antennas ( 10 ). The new components are PC's ( 12 ), ( 16 ), a birefringent medium ( 14 ), N polarizers ( 18 ), and additional optical connections ( 11 ), ( 13 ), ( 15 ) and ( 17 ). This embodiment is essentially an optimized version of the embodiment depicted in FIG. 2 . Instead of the N independent MZDI's ( 7 ), the N interferometers of this embodiment share the input optical coupler. The modulated optical signal has a linear polarization state at the output of the electro-optic modulator ( 4 ). The birefringent medium ( 14 ) allows propagation of an optical signal along two orthogonal polarization axes, which have different propagation velocities. Therefore, this medium allows obtaining a time delay τ between two orthogonally polarized optical signals aligned with the orthogonal polarization axes of the medium. The PC ( 12 ) sets the SOP of the modulated optical signal at an angle of 45° relative to one of the axes of the birefringent medium ( 14 ). At the output of said birefringent medium ( 14 ) two modulated optical signals, orthogonally polarized and time delayed by τ between each other, are obtained. So, the PC ( 12 ) and the birefringent medium ( 14 ) are the input optical coupler and the delay lines of the proposed MZDI's. The optical splitter ( 5 ) is used to obtain N copies of the orthogonally polarized optical signals. Depending on the angular orientation set by the PC's ( 16 ), the orthogonally polarized signals are added with different weights using the polarizers ( 18 ). Hence, the PC's ( 16 ) and the polarizers ( 18 ) are the output optical couplers with tunable coupling ratio of the proposed MZDI's. After being time delayed, each signal copy is converted to the electrical domain using a photodetector ( 9 ) and subsequently sent to its respective elementary antenna ( 10 ). Briefly, the direction of the radiated electrical field is defined through the manipulation of the PC's ( 16 ). The third embodiment is shown in FIG. 4 . This embodiment comprises N ML sources ( 19 ) optically connected to N PC's ( 21 ). The signals generated by the N ML sources are multiplexed in the wavelength, using a wavelength multiplexer ( 23 ) which is optically connected to the electro-optic modulator ( 4 ). All multiplexed signals are modulated the same way, and then introduced into the birefringent medium ( 14 ). The multiplexed signals at the output of the birefringent medium are now de-multiplexed using a wavelength de-multiplexer ( 24 ) with N outputs, where each one of the N outputs is connected to a PC ( 16 ) and a polarizer ( 18 ). Several optical connections are presented at ( 20 ), ( 22 ), ( 2 ), ( 11 ), ( 15 ), ( 6 ), ( 17 ) and ( 8 ). Of course, the N photodetectors ( 9 ) and N elementary antennas ( 10 ) are the same as in previously described embodiments. Although previous embodiments are based on a ML source ( 1 ) and an optical splitter ( 5 ) which is not sensitive to the wavelength, the present embodiment is based on wavelength multiplexing for N ML sources. The optical splitter ( 5 ) which is not sensitive to the wavelength is replaced by a wavelength multiplexer ( 23 ) and de-multiplexer ( 24 ). The MZDI associated with each ML source is now composed by a PC ( 21 ), the birefringent medium ( 14 ), another PC ( 16 ) and its respective polarizer ( 18 ). The coupling ratio and consequently the time delay associated to a ML source can be tuned through the PC ( 21 ). Here, all the PC's ( 16 ) have the same function, which is to align the polarization axis of the birefringent medium ( 14 ) at an angle of 45° relative to one of the polarizer's axes ( 18 ). Such functions belonging to PC's ( 21 ) and ( 16 ) can be performed by PC's ( 16 ) and ( 21 ) respectively. It should be noted that, in the first situation, it is required that the electro-optic modulator is not sensitive to the polarization of the ML sources ( 19 ). Therefore, in this embodiment the MZDI's can have both the input and output optical couplers with tunable coupling ratio. The fourth embodiment is shown in FIG. 5 . This embodiment is quite similar to the second embodiment sharing most of its functioning, but differs in the following details. The polarizers ( 18 ) were replaced by VOA's ( 25 ) sensitive to the polarization. This device allows an independent attenuation for the SOP's of the input optical signal. The PC's ( 16 ) are used to align the polarization orthogonal axes of the birefringent medium ( 14 ) with the polarization orthogonal axes of the device ( 25 ). As a consequence of the replacement of polarizers ( 18 ) by devices ( 25 ), the polarization orthogonal signals are not added to the electrical domain. In this embodiment, the polarization orthogonal signals are simultaneously added in the photodetection process, which means the electrical signal consists in adding the polarization orthogonal signals detected. The MZDI's are therefore partly implemented both on the optical and electrical domains. The coupling ratio can be tuned through the adjustment of the VOA's ( 25 ) sensitive to polarization. To perform the addition in the electrical domain, one needs that the phase information of the orthogonally polarized optical signals is preserved at the electrical domain. As a result, this embodiment is limited to optical signals with SSB modulation. The main difference between this and the second embodiment relates to the fact that this embodiment has a incoherent operation, unlike the third embodiment where orthogonally polarized optical signals are coherently added in optical domain polarization. Briefly, the beamforming of the radiated electrical field is defined through the tuning of devices ( 25 ). The fifth embodiment is shown in FIG. 6 . This embodiment is quite similar to the third embodiment sharing most of its functioning, but differs in the following details. The polarizers ( 18 ) are replaced by VOA's ( 25 ) sensitive to polarization. The PC's ( 16 ) are used to align the orthogonal axes in the polarization of the birefringent medium ( 14 ) with the polarization orthogonal axes of the device ( 25 ). The purpose of these modifications is explained in fourth embodiment. Therefore, this embodiment is also limited to optical signals with SSB modulation. The main difference between this and the third embodiment relates to the fact that this embodiment has a incoherent operation, unlike the third embodiment where orthogonally polarized optical signals are coherently added in optical domain polarization. Briefly, the beamforming of the radiated electrical field is defined through the tuning of devices ( 25 ).
This invention discloses a photonic system to beamform the electric field yield by a phased array antenna. The system function relies on a photonic tunable delay line, which consists on an optical Mach-Zehnder interferometer with a predefined time delay difference between arms. The time delay is tuned by adjusting the coupling ratio between the power applied to each one of the interferometer's delay lines. Three embodiments are proposed, wherein one of them just uses a single delay line and a single monochromatic light source, independently of the quantity of the array elementary antennas.
Briefly summarize the invention's components and working principles as described in the document.
[ "CROSS-REFERENCE TO RELATED APPLICATIONS This application is a National Phase Application of PCT International Application No. PCT/PT2010/000061, International Filing Date Dec. 9, 2010, claiming priority of Portuguese Patent Application No. 105190, filed Jul. 8, 2010, which is hereby incorporated by reference.", "FIELD OF THE INVENTION This invention discloses a photonic system and method with the purpose of beamforming the electric field yield by a phased array antenna (PAA).", "The system relies on a photonic tunable optical delay line (TODL), which is an Mach-Zehnder optical interferometer with a predefined differential time delay between arms.", "The time delay is tuned by adjusting the coupling ratio between the power applied to each one of the interferometer's delay lines.", "Three embodiments are proposed, wherein one of them just uses a single delay line and a single monochromatic light (ML) source, independently of the quantity of elementary antennas of the phased array.", "The application of the described TODL in a photonic system with the purpose of beamforming the electric field yield by a PAA has not been found in the present state of the art.", "The proposed system is appropriate to wireless communication systems with high frequency RF carriers, which allow handling with high data transmission rates.", "The proposed invention presents a novel approach in beamforming systems for the electric field radiated by a PAA.", "PAA's are being increasingly used, because such antennas allow directing the radiated beam precisely to any target direction, without using any mechanical displacement.", "Since the bandwidth of data transmission is growing in wired or wireless communication systems, interconnecting systems between both these types of communication systems are required, which allow high data transmission rates.", "Let us consider the following example: a wireless network system with high data transmission rates (≦1 Gb/s) can use a radio over fiber (RoF) system to connect a central office to a remote PAA.", "Subsequently, the PAA will direct the beam in a target direction using the proposed system, since it allows the acceptance of high data transmission rates.", "Another area of interest outside communication systems is radio astronomy, which requires advanced antenna technology to monitor signals arriving from outer space with low power and high bandwidths.", "In comparison with the photonic beamforming techniques reported so far, the proposed system is rather simple and is based on a well-known optics device, the Mach-Zehnder delay interferometer (MZDI).", "Its implementation is made with commercially available components.", "It also allows a very fast beam tuning, particularly when its implementation uses integrated optics.", "According to its inventors point of view, the main advantage is that it just requires one optical delay line (the birefringent medium in the embodiment shown in FIG. 3 ) and a single ML source, independently of the quantity of elementary antennas.", "This feature was not found in any techniques reported in prior art's literature.", "BACKGROUND ART DESCRIPTION A PAA comprises N antennas disposed along the three spatial dimensions.", "The antennas which form the PAA are known as elementary antennas.", "A PAA allows the optimization and the beamforming of the radiated electrical field through the adjustment of the amplitude and phase of the radio frequency (RF) signals sent to each elementary antenna.", "This is an exclusive feature for the PAA's, since in an individual antenna the optimization of the radiated electrical field depends on the antenna's design.", "In addition, the beamforming of the radiated electrical field depends on the spatial orientation of the antenna.", "As previously said, the beamforming of the electrical field radiated by the PAA can be controlled through the phase of the RF signals applied to each elementary antenna.", "More precisely, the PAA can be fed by a single RF signal, which is split to all elementary antennas including a tunable phase shift.", "Although tunable, the phase shift is constant.", "This means the induced phase shift value is correct only for a specific RF frequency.", "In a PAA, this implies that the emitted frequency should be constant.", "Otherwise, different RF frequencies get different phase shifts, and so the beamforming of the electric field becomes dependent on the emitted frequency.", "In the case of data transmission over one RF carrier frequency, this implies that the data signal bandwidth should be as low as possible.", "Since there are many applications with high bandwidth (e.g., RADAR signals, Gb/s wireless networks, radio astronomy, etc.), the beamforming of the radiated electric field cannot be efficiently performed with such a technique.", "This problem can be solved using phase shifts that depend on RF frequency.", "In practice, a phase shift depending on frequency consists in a time delay line.", "Therefore, instead of a phase shift, each elementary antenna should include a tunable time delay.", "The electrical implementation of a tunable time delay is particularly challenging at high frequencies, since increasing time delays implies increasing the length of the delay line, which in turn leads to greater insertion losses and a reduction in bandwidth.", "Such disadvantages are overcome using photonic implementations of tunable delay lines.", "The advantages of photonic systems consist on low losses, broad bandwidth, lighter weights, smaller dimensions and immunity to electromagnetic interference.", "Generally, a PAA with tunable photonic delay lines is characterized in that it has an electro-optical modulator, which converts the RF signal to the optical domain, followed by an optical processing system which delays and distributes the modulated optical signal according to what the needs of the different antennas are.", "The optical signals are converted to the electrical domain using photodetectors.", "The patents summarized below describe different implementations of photonic TODL's, which can be applied to PAA.", "U.S. Pat. No. 5,428,218 discloses a photonic TODL based on spatial multiplexing.", "In such free-space implementation, the optical signal is directed into a given optical fiber through the adjustment of mirrors.", "As different optical fibers have different lengths, one can get a discrete tuning of the time delay added to the optical signal.", "This implementation also includes the possibility of having a multi-beam system, e.g., the system can be simultaneously used by more than one optical signal.", "U.S. Pat. No. 5,978,125 discloses a photonic TODL based on polarization multiplexing.", "In a birefringent medium, an optical signal with a specific state-of-polarization (SOP) has a higher time delay than the orthogonal SOP.", "By selecting one of the two SOP's, the added time delay can then be controlled.", "This method is described in a cascaded configuration, in which serial birefringent media are intercalated by polarization controllers (PC's).", "As a result, a discrete delay tuning is obtained.", "U.S. Pat. No. 5,461,687 discloses a photonic TODL based on dispersive means.", "By tuning the wavelength of the input optical signal the path by which the signal propagates changes, resulting in a tunable time delay.", "In this patent, the dispersive mean is implemented in a free space using a diffraction grating.", "Another possible option is to use fiber Bragg gratings (FBG's) located in different points of an optical fiber.", "U.S. Pat. No. 5,751,466 discloses a photonic TODL which uses the frequency response of a photonic bandgap device.", "An example of such a device is a FBG.", "This device consists of a dielectric structure in which the refractive index varies longitudinally.", "The control of the refractive index's variation along the structure results in changing the frequency response of the device, therefore affecting the time delay added to the photonic signal.", "U.S. Pat. No. 7,558,450 B2 discloses a photonic TODL composed by three resonant elements coupled to a waveguide.", "This implementation is limited to single sideband (SSB) optical signals.", "The symmetric displacement in the frequency of two resonant elements enables the adjustment of time delay induced to the RF carrier.", "The third resonant element adjusts the phase of the optical carrier (OC) in order to avoid involuntary phase shifting of RF signal.", "Of greater importance than the tuning method, is the fact that this patent is clearly appropriate to RF signals without any spectral content between the optical and the RF carriers.", "As a result, the TODL's frequency response is irrelevant at frequencies located between the RF carrier and the OC.", "BRIEF DESCRIPTION OF THE DRAWINGS The following description is based on the drawings attached hereto, which are represented without any restrictions: In FIG. 1 the response in amplitude and the photonic TODL group delay, considering different coupling ratios α among the power applied to each one of the interferometer's optical delay lines.", "FIG. 2 shows a first embodiment of the invention;", "FIG. 3 shows a second embodiment of the invention;", "and FIG. 4 shows a third embodiment of the invention.", "FIG. 5 shows a fourth embodiment of the invention.", "FIG. 6 shows a fifth embodiment of the invention.", "DETAILED DESCRIPTION OF THE INVENTION The system proposed for beamforming the electric field yield by a PAA can be divided in three subsystems.", "In the first subsystem, the RF signal modulates a monochromatic optical carrier.", "The resulting modulated optical signal is split into N copies, where N is the number of elementary antennas.", "Each copy is introduced into a TODL, and then reconverted to the electrical domain by means of a photodetector.", "Each photodetector is connected to the respective elementary antenna.", "The key element of a beamforming system is the tunable delay line, because generally a PAA with N antennas requires N tunable delay lines.", "The proposed TODL consists of a MZDI with two arms.", "The MZDI is composed of an input optical coupler to which two delay lines and an output coupler which adds the signals coming from both lines.", "The delay lines have a fixed time delay difference τ.", "One of the optical couplers has a tunable coupling ratio, i.e., the optical power ratio in the two delay lines can be tuned.", "According to what is claimed in patent PT 104237, the proposed MZDI consists of an optical filter with tunable response, which approximately corresponds to a weighted average of the delay lines responses.", "The tuning is carried out through the adjustment of the optical power ratio between the two delay lines.", "As a result, a desired TODL with a tuning ranging from 0 to τ is obtained.", "In terms of a mathematic expression, the frequency response of the MZDI is given by H ⁡ ( f ) = 2 2 ⁡ [ α + 1 - α 2 ⁢ ⅇ - j2π ⁢ ⁢ f ⁢ ⁢ τ ] , ( 1 ) where 0≦α≦1 is the coupling ratio and f is the frequency.", "The amplitude response ∥H(f)∥ 2 and the group delay τ(f) can be derived from ( 1 ),  H ⁡ ( f )  2 = 1 2 ⁢ { 1 + 2 ⁢ α ⁢ 1 - α 2 ⁢ cos ⁡ ( 2 ⁢ π ⁢ ⁢ f ⁢ ⁢ τ ) } , ( 2.1 ) τ ⁡ ( f ) = τ ⁢ { 1 - α 2 + α ⁢ 1 - α 2 ⁢ cos ⁡ ( 2 ⁢ π ⁢ ⁢ f ⁢ ⁢ τ ) 1 + 2 ⁢ α ⁢ 1 - α 2 ⁢ cos ⁡ ( 2 ⁢ π ⁢ ⁢ f ⁢ ⁢ τ ) } .", "( 2.2 ) Both derived equations show that the TODL has a periodic frequency response with a period 1/τ.", "The amplitude response and the group delay are depicted in FIG. 1 for different values of α.", "As predicted by ( 2 .", "1 ) and ( 2 .", "2 ), both the amplitude response and the group delay are affected by α.", "As a result, the optical signal must be properly centered with the MZDI's frequency response.", "The absolute value of the amplitude response can be adjusted by means of variable optical attenuators (VOA's), located at the input or output of the TODL's, or using electrical amplifiers for the signals detected.", "Generally, a RF signal modulated over an OC has three spectral lines located at f 0 −f RF , f 0 and f 0 +f RF , where f 0 is the OC frequency and f RF is the frequency of the RF signal.", "In the case of data transmission, copies of the transmitted sequence spectrum are centered at the three spectral lines.", "Thus, there are two ways for centering the modulated signal spectrum with the MZDI's frequency response.", "The first one consists of setting all the three spectral lines within a single period of the MZDI's response.", "The other way makes use of the fact that the TODL's frequency response is irrelevant to frequencies located between the RF carriers and the OC.", "Each one of the spectral lines is then centered at different maxima of the MZDI's amplitude response.", "The implementation of the proposed photonic system for beamforming the electric field radiated by a PAA is presented through five different architectures.", "Proposed Embodiments The first proposed embodiment is shown in FIG. 2 .", "This embodiment comprises a ML source ( 1 ), optical connections ( 2 ), ( 6 ), ( 8 ), an electro-optic modulator ( 4 ), a 1 to N optical signal splitter ( 5 ), N TODL's based on the proposed MZDI ( 7 ), N photodetectors ( 9 ) and N elementary antennas ( 10 ).", "By means of an electro-optic modulator ( 4 ), the monochromatic signal generated by the light source ( 1 ) is modulated by the electric RF signal ( 3 ) which will be radiated by the PAA.", "The modulated optical signal is split into N copies using a 1 to N optical splitter ( 6 ).", "Each one of the N copies is input into a TODL ( 7 ), which consists of a MZDI ( 7 ) with two arms and tunable coupling ratio.", "Each arm of the MZDI is a fixed optical delay line, where the propagation time difference of both arms is T. The time delay added to each copy of the modulated signal, before such copy enters its TODL ( 7 ), can be predefined by the length of the optical connections ( 6 ).", "After being time delayed, each copy is converted to the electrical domain using a photodetector ( 9 ) and subsequently sent to the respective elementary antenna ( 10 ).", "Briefly, the direction of the radiated electrical field is defined by manipulating the coupling ratios for the N TODL's ( 7 ).", "The second embodiment is shown in FIG. 3 .", "This embodiment also comprises a ML source ( 1 ), optical connections ( 2 ), ( 6 ), ( 8 ), an electro-optic modulator ( 4 ), a 1 to N optical signal splitter ( 5 ), N photodetectors ( 9 ) and N antennas ( 10 ).", "The new components are PC's ( 12 ), ( 16 ), a birefringent medium ( 14 ), N polarizers ( 18 ), and additional optical connections ( 11 ), ( 13 ), ( 15 ) and ( 17 ).", "This embodiment is essentially an optimized version of the embodiment depicted in FIG. 2 .", "Instead of the N independent MZDI's ( 7 ), the N interferometers of this embodiment share the input optical coupler.", "The modulated optical signal has a linear polarization state at the output of the electro-optic modulator ( 4 ).", "The birefringent medium ( 14 ) allows propagation of an optical signal along two orthogonal polarization axes, which have different propagation velocities.", "Therefore, this medium allows obtaining a time delay τ between two orthogonally polarized optical signals aligned with the orthogonal polarization axes of the medium.", "The PC ( 12 ) sets the SOP of the modulated optical signal at an angle of 45° relative to one of the axes of the birefringent medium ( 14 ).", "At the output of said birefringent medium ( 14 ) two modulated optical signals, orthogonally polarized and time delayed by τ between each other, are obtained.", "So, the PC ( 12 ) and the birefringent medium ( 14 ) are the input optical coupler and the delay lines of the proposed MZDI's.", "The optical splitter ( 5 ) is used to obtain N copies of the orthogonally polarized optical signals.", "Depending on the angular orientation set by the PC's ( 16 ), the orthogonally polarized signals are added with different weights using the polarizers ( 18 ).", "Hence, the PC's ( 16 ) and the polarizers ( 18 ) are the output optical couplers with tunable coupling ratio of the proposed MZDI's.", "After being time delayed, each signal copy is converted to the electrical domain using a photodetector ( 9 ) and subsequently sent to its respective elementary antenna ( 10 ).", "Briefly, the direction of the radiated electrical field is defined through the manipulation of the PC's ( 16 ).", "The third embodiment is shown in FIG. 4 .", "This embodiment comprises N ML sources ( 19 ) optically connected to N PC's ( 21 ).", "The signals generated by the N ML sources are multiplexed in the wavelength, using a wavelength multiplexer ( 23 ) which is optically connected to the electro-optic modulator ( 4 ).", "All multiplexed signals are modulated the same way, and then introduced into the birefringent medium ( 14 ).", "The multiplexed signals at the output of the birefringent medium are now de-multiplexed using a wavelength de-multiplexer ( 24 ) with N outputs, where each one of the N outputs is connected to a PC ( 16 ) and a polarizer ( 18 ).", "Several optical connections are presented at ( 20 ), ( 22 ), ( 2 ), ( 11 ), ( 15 ), ( 6 ), ( 17 ) and ( 8 ).", "Of course, the N photodetectors ( 9 ) and N elementary antennas ( 10 ) are the same as in previously described embodiments.", "Although previous embodiments are based on a ML source ( 1 ) and an optical splitter ( 5 ) which is not sensitive to the wavelength, the present embodiment is based on wavelength multiplexing for N ML sources.", "The optical splitter ( 5 ) which is not sensitive to the wavelength is replaced by a wavelength multiplexer ( 23 ) and de-multiplexer ( 24 ).", "The MZDI associated with each ML source is now composed by a PC ( 21 ), the birefringent medium ( 14 ), another PC ( 16 ) and its respective polarizer ( 18 ).", "The coupling ratio and consequently the time delay associated to a ML source can be tuned through the PC ( 21 ).", "Here, all the PC's ( 16 ) have the same function, which is to align the polarization axis of the birefringent medium ( 14 ) at an angle of 45° relative to one of the polarizer's axes ( 18 ).", "Such functions belonging to PC's ( 21 ) and ( 16 ) can be performed by PC's ( 16 ) and ( 21 ) respectively.", "It should be noted that, in the first situation, it is required that the electro-optic modulator is not sensitive to the polarization of the ML sources ( 19 ).", "Therefore, in this embodiment the MZDI's can have both the input and output optical couplers with tunable coupling ratio.", "The fourth embodiment is shown in FIG. 5 .", "This embodiment is quite similar to the second embodiment sharing most of its functioning, but differs in the following details.", "The polarizers ( 18 ) were replaced by VOA's ( 25 ) sensitive to the polarization.", "This device allows an independent attenuation for the SOP's of the input optical signal.", "The PC's ( 16 ) are used to align the polarization orthogonal axes of the birefringent medium ( 14 ) with the polarization orthogonal axes of the device ( 25 ).", "As a consequence of the replacement of polarizers ( 18 ) by devices ( 25 ), the polarization orthogonal signals are not added to the electrical domain.", "In this embodiment, the polarization orthogonal signals are simultaneously added in the photodetection process, which means the electrical signal consists in adding the polarization orthogonal signals detected.", "The MZDI's are therefore partly implemented both on the optical and electrical domains.", "The coupling ratio can be tuned through the adjustment of the VOA's ( 25 ) sensitive to polarization.", "To perform the addition in the electrical domain, one needs that the phase information of the orthogonally polarized optical signals is preserved at the electrical domain.", "As a result, this embodiment is limited to optical signals with SSB modulation.", "The main difference between this and the second embodiment relates to the fact that this embodiment has a incoherent operation, unlike the third embodiment where orthogonally polarized optical signals are coherently added in optical domain polarization.", "Briefly, the beamforming of the radiated electrical field is defined through the tuning of devices ( 25 ).", "The fifth embodiment is shown in FIG. 6 .", "This embodiment is quite similar to the third embodiment sharing most of its functioning, but differs in the following details.", "The polarizers ( 18 ) are replaced by VOA's ( 25 ) sensitive to polarization.", "The PC's ( 16 ) are used to align the orthogonal axes in the polarization of the birefringent medium ( 14 ) with the polarization orthogonal axes of the device ( 25 ).", "The purpose of these modifications is explained in fourth embodiment.", "Therefore, this embodiment is also limited to optical signals with SSB modulation.", "The main difference between this and the third embodiment relates to the fact that this embodiment has a incoherent operation, unlike the third embodiment where orthogonally polarized optical signals are coherently added in optical domain polarization.", "Briefly, the beamforming of the radiated electrical field is defined through the tuning of devices ( 25 )." ]
RELATED APPLICATION A related application is Ser. No. 09/405,017, filed Sep. 27, 1999, entitled “Method of Manufacturing a Transformer Coil With a Disposable Wrap and and Mold and Integrated Winding Mandrel” filed concurrently herewith by Thomas J. Lanoue, Wayne Lambert and Charles Sarver and assigned to the same assignee as the present application, the disclosure of which is incorporated herein by that reference thereto. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method of manufacturing transformer windings embedded in casting resin and more particularly to a method of manufacturing a transformer coil encapsulated in casting resin utilizing a disposable casting mold wherein the disposable mold acts both as a winding mandrel and as an inner mold shell for resin encapsulation. The invention is particularly suited to the manufacture of non-standard oval shaped or circular shaped epoxy encapsulated coils for dry type distribution transformers. 2. Description of the Prior Art Currently the state of the art is precision made standard sized re-usable round shaped mandrels and molds in fixed size increments with costly tap inserts. Examples of prior art methods of encapsulating transformer coils are disclosed in U.S. Pat. Nos. 4,337,219, 4,540,536, 5,036,580 and 5,633,019. SUMMARY OF THE INVENTION It is an object of the invention to provide a method of manufacturing a transformer coil encapsulated in casting resin utilizing a disposable casting mold wherein the disposable mold acts both as a winding mandrel and as an inner mold shell for resin encapsulation. It is a further object of the invention to provide a method of manufacturing a wide variety of oval or circular shaped resin encapsulated transformer coils by making the disposable inner and outer molds from low cost sheet metal. The invention process provides the advantages of flexible oval or circular dimensional sizes, flexible and incremental oval or circular shapes providing substantially reduced mandrel and molding costs, elimination of costly standard mold storage, elimination of the need for standard winding mandrels, and facilitates the opportunity to manufacture transformer coils in a round to oval configuration. In accordance with the foregoing objects and advantages the present invention provides a method of manufacturing a transformer coil encapsulated in casting resin utilizing a disposable casting mold wherein the disposable mold acts both as a winding mandrel and as an inner mold shell for resin encapsulation. The method comprises the steps of forming an annular inner mold of predetermined shape around a winding mandrel of a coil winding machine to produce an integrated winding form/mandrel/inner mold for use in the winding process, placing the integrated winding/mandrel/inner mold in a winding machine, winding a coil around the inner mold while in the winding machine, removing the inner mold and coil wound thereon from the winding machine, forming an annular outer mold of predetermined shape over the finished coil to provide a manufactured coil and mold assembly, providing a seal for the manufactured coil and mold assembly to prevent casting resin leaks during the encapsulation process, filling the mold assembly with casting resin to encapsulate the coil, permitting the casting resin to harden on the coil, and removing the encapsulated coil from the casting mold assembly. In accordance with another aspect of the invention the annular outer mold is provided with a mold dome. The method of the invention includes placing gasket material at the ends of the inner and outer molds and placing end plates against the material on the ends of the inner and outer molds to form a casting mold. The method further includes placing coil support plates at the top and each end of the mold dome of the outer mold to support the weight of the coil during encapsulation and curing processes, applying a predetermined compression force to the end plates ofthe casting mold and placing the casting mold containing the wound coil in a horizontal position in an evacuated chamber and pouring casting resin into an opening in the mold dome in the outer mold of the casting mold to encapsulate the coil. In accordance with another aspect of the invention, the inner and outer molds are formed of sheet metal. In accordance with another aspect of the invention, the predetermined shape of the inner and outer molds is oval shaped for the production of an oval coil. In accordance with another aspect of the invention the predetermined shape of the inner and outer molds is circular shaped for the production of a round coil. In accordance with another aspect of the invention at least one of the inner and outer molds is of one-piece construction. In accordance with another aspect of the invention the inner mold includes inturned flanges at the radial ends of the sheet metal and removably secured together mechanically for ease of mold disassembly and the method includes the step of placing a gasket between the inturned flanges of the innermold before removably securing together the flanges and applying a liquid sealant to the outside of the mold gasket area. In accordance with a further aspect of the invention, the method includes the step of applying a resin release agent to all exposed surfaces of the inner mold, applying a glass net to the exposed surfaces of the inner mold after the application of the resin release agent and prior to winding the coil onto the inner mold. In accordance with a further aspect of the invention, the method includes the step of applying a glass net over the finished coil winding and applying a resin release agent to the inside of the outer mold prior to placing the outer mold over the coil. In accordance with another aspect of the invention, the method includes the step of installing a plurality of compression rods to interconnect the end plates, and applying a torque to the compression rods to apply the predetermined compression force to the end plates of the casting mold. In accordance with another aspect of the invention at least one of the inner and outer molds is of two-piece construction. For a more detailed disclosure of the invention and for further objects and advantages thereof, reference is to be had to the following description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a casting mold assembly useful in practicing the method of the present invention. FIG. 2 is a perspective view of the mold assembly similar to FIG. 1 but with certain parts removed for purposes of clarity. FIG. 3 is a sectional view taken along the lines 3 — 3 in FIG. 1 . FIG. 4 is a top plan view of the mold assembly illustrated in FIG. 1 . FIG. 5 is a perspective view of a casting mold assembly for manufacturing an oval transformer coil in accordance with the present invention. FIG. 6 is a sectional view taken along the lines 6 — 6 in FIG. 5 . DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is particularly suited for manufacturing non-standard oval or round shaped epoxy encapsulated high voltage coils for dry type distribution transformers. The invention to be described herein includes a new process of winding a high voltage oval or round coil over a disposable mold which acts as both a winding mandrel and an inner mold shell for epoxy encapsulation. The invention also includes a simple technique of making the inner and outer molds using low cost sheet metal. The complete winding and molding processes can all be conducted on a standard winding machine for either aluminum or copper conductors wound as in a layer or disk type format. Referring to the drawings it will be seen that FIGS. 1-4 relate to a casting mold assembly for manufacturing a round or circular transformer coil in accordance with the present invention and FIGS. 5 and 6 relate to a casting mold assembly for manufacturing an oval shaped transformer coil in accordance with the present invention. Referring to FIG. 1 there is illustrated a casting mold assembly 10 useful in practicing the method of the present invention. A mold assembly 10 includes an annular inner mold 12 of predetermined shape. As may be seen in FIG. 2 the inner mold 12 is of circular shape and preferably is formed from thin sheet metal so that it is disposable and inexpensive. In one form ofthe invention the inner mold 12 was formed from a mill standard mild steel of 0.048 thickness commonly referred to as 18 gauge material. For transformer coil KVA classes larger than 1500 KVA, a 14 gauge material is preferred. The inner mold 12 may be made of one piece or two piece construction. The two-piece construction is illustrated in FIGS. 1-3. The preferred fabrication method is roll forming, however, conventional press break multiple bending step processing is possible for the two-piece mold construction illustrated in FIGS. 1-3. The inner mold 12 has flanges 12 a which may be secured mechanically by either bolting or clamping. A gasket material, such for example as 6.3 mm rubber (not shown) is inserted between the mold flange components 12 a for sealing and spacing. The spacing generated by the gasket greatly enhances the ease of mold disassembly. Mechanical strength of both the round and oval coil design requires internal support longitudinally across the coil to maintain shape consistently. Typically there are three mechanical supports equally spaced inside the mold 12 , beginning at about 4 inches from the end of the mold. In the embodiment illustrated in FIGS. 1-4 for the round coil two inner mold support bars 18 have been illustrated. The ends of the inner mold support bars 18 are connected to spacer bars 20 by bolts 22 , FIG. 3 . The annular outer mold 24 , FIGS. 2 and 3, is fabricated into either a round or oval shape and is constructed of 18 gauge or 1.22 mm thick cold rolled steel so as to be disposable. The outer mold 24 is of one-piece construction with an integrated dome and tap area 26 . The tap or dome area 26 , being an open exposed area of the coil and mold, makes it well suited for the epoxy filling position for the encapsulation process. This also serves as a reserve area for make up of any epoxy shrinkage. The following is a detailed step by step manufacturing process for construction of a cast coil in accordance with the present invention. The sheet metal inner mold 12 is prepared by installing a rubber gasket to the flanges of the mold and securing it by bolting or clamping. A liquid silicone sealant preferably is applied to the outside of the mold gasket area and permitted to air dry for a predetermined period. It has been found that a minimum of four hours for air drying is suitable and this can take place during the winding process. The inner mold 12 is then installed onto an expanding mandrel of a standard winding machine (not shown) and expanded until secure. An epoxy release agent preferably is applied to all exposed surfaces of the inner mold 12 in accordance with recommendations of the epoxy manufacturer. Apre-pregnated glass netmaterial 28 is applied to the innermold 12 to ensure good surface coverage. It is preferable that the glass net be applied with the large strands in the radial direction of the coil. Sectional strips may be used on the outer surface of the coil to reduce material content. A coil winding 30 is then applied by the winding machine to the inner mold 12 . A pre-pregnated glass net 32 is then installed over the finished coil winding 30 to provide an outer layer of glass net which also is preferably applied radially. The outer mold 24 is then installed and secured over the finished coil 30 . This process may be performed while the inner mold 12 is on the mandrel or it may be performed at a remote assembly site. After the coil 30 is removed from the winding equipment, the inner support members 18 are inserted. These support members 18 maintain the coil shape on large coils and remain inside the inner mold 12 during the entire encapsulation process. Prior to installing the outer mold 24 , an epoxy release agent is applied to the inside of the outer mold 24 . For best results continuous and consistent coverage is essential. Thereafter, the outer mold 24 is installed over the coil winding 30 . A gasket material 34 is placed over the inner and outer disposable mold ends as shown in FIGS. 1 and 4. The application of a small amount of suitable adhesive such as super glue to the mold and gasket mating surfaces will aid in securing the gasket 34 to the mold ends. A pair of end plates 36 , 36 are set in place against the gasket and mold surfaces and temporarily secured in place while verifying the squareness and positioning ofthe inner and outer molds 12 and 24 . A plurality of compression rods 38 are installed to connect the end plates 36 . The compression rods 38 have threaded ends for receiving nut members 40 . At this point in the process the nut members 40 are not tightened to apply torque to the compression rods 38 . A plurality of coil support plates 42 are installed at the top and each end of the mold dome area 26 using small clamps 44 . This will support the weight of the coil 30 during the encapsulation and curing processes. Torque is now applied to the compression rods 38 by tightening the nut members 40 . This is preferably done by starting at one side of the end plates and moving in a crossing sequence until torque values in the order of 130 in lbs. to 140 in lbs. is established on all of the remaining compression rods 38 . Torque values preferably are established by 40 to 50 in. lb. increments. The length of the inner and outer molds 12 and 24 preferably are manufactured to close tolerances in the order of 0.4 mm. This is desirable for obtaining consistent gasket sealing to end plates. With the process described venting of the innermold area is desirable at the end plates at 36 a for equalization of pressure during the casting process. With the casting mold assembly 10 in a horizontal position it is placed in a vacuum chamber and a casting resin 48 , such for example as an epoxy resin, is introduced through the openings in the support plates 42 to fill the mold with the casting resin. Such a vacuum casting process is well known in the art. It is preferable that the mold assembly 10 be maintained horizontal or level during the gelling and curing process. After the curing process has been completed, the outer and inner molds are removed and the encapsulated coil is removed from the casting mold assembly. While the present invention has been described in connection with a method of making a round winding configuration in FIGS. 1-4, it is equally applicable to oval winding configurations. The principle difference is in the shape of the inner and outer molds. An example of a mold assembly for oval shaped coils is illustrated in FIGS. 5 and 6. The casting mold assembly 50 shown in FIGS. 5 and 6 includes an oval shaped inner mold 52 and an oval shaped outer mold 54 . Both the inner and outer molds 52 and 54 are made of low cost sheet metal similar to the inner and outer molds 12 and 24 illustrated in FIGS. 1-4. A glass net material is applied over the inner mold 52 and a coil winding 56 is then applied by the winding machine to the inner mold 52 . Another layer of glass net is then installed over the finished coil winding 56 to provide an outer layer of glass net. The outer mold 54 is then installed and secured over the finished coil 56 . Mechanical strength of the oval coil design requires internal support longitudinally across the coil to maintain shape consistency. Typically there are three mechanical supports in the form of disks 58 equally spaced inside the mold, beginning about 4 inches from the end of the mold. The mechanical support work pieces may be fabricated on a punch machine to obtain the oval shape. The material thickness for the inner support may be 14 gauge (1.88 mm) or 11 gauge (3.17 mm). The other parts of the casting mold assembly 50 are similar to the parts of the casting mold assembly 10 and have been identified with similar reference characters with the addition of a prime. From the foregoing it will be seen that the present invention includes a new process of winding either round or oval transformer coils over a disposable mold which acts as both a winding mandrel and as an inner mold shell for epoxy encapsulation. The invention also includes a simple technique of making the inner and outer molds using low cost sheet metal. The invention has many advantages over conventional fixed sized standard winding mandrels and casting molds. Two of the features or advantages are the use of low cost sheet metal to form a flexible sized oval or circular mandrel and the horizontal molding concept. The complete winding and molding processes can be all conducted on a standard winding machine for either aluminum or copper conductor wound in a layer or disk type format. The process of the present invention provides the advantages of flexible round or oval dimensional sizes, flexible and incremental round or oval shapes providing substantially reduced mandrel and molding costs, elimination of costly standard mold storage, elimination of the need for standard winding mandrels, controlled epoxy thickness for increased dielectric strength and reliability, improved manufacturer ability, reduction in epoxy cost, horizontal epoxy casting and facilitates the opportunity to manufacture transformer coils in a round or oval configuration. The present process using a disposable integrated winding mandrel represents a substantial improvement over the current state ofthe art which uses precision made standard sized re-usable round shaped mandrels and molds in fixed size increments. While a preferred embodiment ofthe present invention has been described and illustrated, it is to be understood that further modifications thereof can be made without departing from the scope of the appended claims.
A method of manufacturing a transformer coil encapsulated in casting resin utilizing a disposable casting mold where the disposable mold acts both as a winding mandrel and as an inner mold shell for resin encapsulation. The disposable casting mold may be oval shaped or circular shaped depending upon the desired shape of the coils to be encapsulated. The inner and outer mold shells are made from thin sheet metal and thus may be adjusted for the manufacture of a wide variety of sizes of oval shaped or circular shaped epoxy encapsulated coils.
Summarize the key points of the given document.
[ "RELATED APPLICATION A related application is Ser.", "No. 09/405,017, filed Sep. 27, 1999, entitled “Method of Manufacturing a Transformer Coil With a Disposable Wrap and and Mold and Integrated Winding Mandrel”", "filed concurrently herewith by Thomas J. Lanoue, Wayne Lambert and Charles Sarver and assigned to the same assignee as the present application, the disclosure of which is incorporated herein by that reference thereto.", "BACKGROUND OF THE INVENTION 1.", "Field of the Invention This invention relates to a method of manufacturing transformer windings embedded in casting resin and more particularly to a method of manufacturing a transformer coil encapsulated in casting resin utilizing a disposable casting mold wherein the disposable mold acts both as a winding mandrel and as an inner mold shell for resin encapsulation.", "The invention is particularly suited to the manufacture of non-standard oval shaped or circular shaped epoxy encapsulated coils for dry type distribution transformers.", "Description of the Prior Art Currently the state of the art is precision made standard sized re-usable round shaped mandrels and molds in fixed size increments with costly tap inserts.", "Examples of prior art methods of encapsulating transformer coils are disclosed in U.S. Pat. Nos. 4,337,219, 4,540,536, 5,036,580 and 5,633,019.", "SUMMARY OF THE INVENTION It is an object of the invention to provide a method of manufacturing a transformer coil encapsulated in casting resin utilizing a disposable casting mold wherein the disposable mold acts both as a winding mandrel and as an inner mold shell for resin encapsulation.", "It is a further object of the invention to provide a method of manufacturing a wide variety of oval or circular shaped resin encapsulated transformer coils by making the disposable inner and outer molds from low cost sheet metal.", "The invention process provides the advantages of flexible oval or circular dimensional sizes, flexible and incremental oval or circular shapes providing substantially reduced mandrel and molding costs, elimination of costly standard mold storage, elimination of the need for standard winding mandrels, and facilitates the opportunity to manufacture transformer coils in a round to oval configuration.", "In accordance with the foregoing objects and advantages the present invention provides a method of manufacturing a transformer coil encapsulated in casting resin utilizing a disposable casting mold wherein the disposable mold acts both as a winding mandrel and as an inner mold shell for resin encapsulation.", "The method comprises the steps of forming an annular inner mold of predetermined shape around a winding mandrel of a coil winding machine to produce an integrated winding form/mandrel/inner mold for use in the winding process, placing the integrated winding/mandrel/inner mold in a winding machine, winding a coil around the inner mold while in the winding machine, removing the inner mold and coil wound thereon from the winding machine, forming an annular outer mold of predetermined shape over the finished coil to provide a manufactured coil and mold assembly, providing a seal for the manufactured coil and mold assembly to prevent casting resin leaks during the encapsulation process, filling the mold assembly with casting resin to encapsulate the coil, permitting the casting resin to harden on the coil, and removing the encapsulated coil from the casting mold assembly.", "In accordance with another aspect of the invention the annular outer mold is provided with a mold dome.", "The method of the invention includes placing gasket material at the ends of the inner and outer molds and placing end plates against the material on the ends of the inner and outer molds to form a casting mold.", "The method further includes placing coil support plates at the top and each end of the mold dome of the outer mold to support the weight of the coil during encapsulation and curing processes, applying a predetermined compression force to the end plates ofthe casting mold and placing the casting mold containing the wound coil in a horizontal position in an evacuated chamber and pouring casting resin into an opening in the mold dome in the outer mold of the casting mold to encapsulate the coil.", "In accordance with another aspect of the invention, the inner and outer molds are formed of sheet metal.", "In accordance with another aspect of the invention, the predetermined shape of the inner and outer molds is oval shaped for the production of an oval coil.", "In accordance with another aspect of the invention the predetermined shape of the inner and outer molds is circular shaped for the production of a round coil.", "In accordance with another aspect of the invention at least one of the inner and outer molds is of one-piece construction.", "In accordance with another aspect of the invention the inner mold includes inturned flanges at the radial ends of the sheet metal and removably secured together mechanically for ease of mold disassembly and the method includes the step of placing a gasket between the inturned flanges of the innermold before removably securing together the flanges and applying a liquid sealant to the outside of the mold gasket area.", "In accordance with a further aspect of the invention, the method includes the step of applying a resin release agent to all exposed surfaces of the inner mold, applying a glass net to the exposed surfaces of the inner mold after the application of the resin release agent and prior to winding the coil onto the inner mold.", "In accordance with a further aspect of the invention, the method includes the step of applying a glass net over the finished coil winding and applying a resin release agent to the inside of the outer mold prior to placing the outer mold over the coil.", "In accordance with another aspect of the invention, the method includes the step of installing a plurality of compression rods to interconnect the end plates, and applying a torque to the compression rods to apply the predetermined compression force to the end plates of the casting mold.", "In accordance with another aspect of the invention at least one of the inner and outer molds is of two-piece construction.", "For a more detailed disclosure of the invention and for further objects and advantages thereof, reference is to be had to the following description taken in conjunction with the accompanying drawings.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a casting mold assembly useful in practicing the method of the present invention.", "FIG. 2 is a perspective view of the mold assembly similar to FIG. 1 but with certain parts removed for purposes of clarity.", "FIG. 3 is a sectional view taken along the lines 3 — 3 in FIG. 1 .", "FIG. 4 is a top plan view of the mold assembly illustrated in FIG. 1 .", "FIG. 5 is a perspective view of a casting mold assembly for manufacturing an oval transformer coil in accordance with the present invention.", "FIG. 6 is a sectional view taken along the lines 6 — 6 in FIG. 5 .", "DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is particularly suited for manufacturing non-standard oval or round shaped epoxy encapsulated high voltage coils for dry type distribution transformers.", "The invention to be described herein includes a new process of winding a high voltage oval or round coil over a disposable mold which acts as both a winding mandrel and an inner mold shell for epoxy encapsulation.", "The invention also includes a simple technique of making the inner and outer molds using low cost sheet metal.", "The complete winding and molding processes can all be conducted on a standard winding machine for either aluminum or copper conductors wound as in a layer or disk type format.", "Referring to the drawings it will be seen that FIGS. 1-4 relate to a casting mold assembly for manufacturing a round or circular transformer coil in accordance with the present invention and FIGS. 5 and 6 relate to a casting mold assembly for manufacturing an oval shaped transformer coil in accordance with the present invention.", "Referring to FIG. 1 there is illustrated a casting mold assembly 10 useful in practicing the method of the present invention.", "A mold assembly 10 includes an annular inner mold 12 of predetermined shape.", "As may be seen in FIG. 2 the inner mold 12 is of circular shape and preferably is formed from thin sheet metal so that it is disposable and inexpensive.", "In one form ofthe invention the inner mold 12 was formed from a mill standard mild steel of 0.048 thickness commonly referred to as 18 gauge material.", "For transformer coil KVA classes larger than 1500 KVA, a 14 gauge material is preferred.", "The inner mold 12 may be made of one piece or two piece construction.", "The two-piece construction is illustrated in FIGS. 1-3.", "The preferred fabrication method is roll forming, however, conventional press break multiple bending step processing is possible for the two-piece mold construction illustrated in FIGS. 1-3.", "The inner mold 12 has flanges 12 a which may be secured mechanically by either bolting or clamping.", "A gasket material, such for example as 6.3 mm rubber (not shown) is inserted between the mold flange components 12 a for sealing and spacing.", "The spacing generated by the gasket greatly enhances the ease of mold disassembly.", "Mechanical strength of both the round and oval coil design requires internal support longitudinally across the coil to maintain shape consistently.", "Typically there are three mechanical supports equally spaced inside the mold 12 , beginning at about 4 inches from the end of the mold.", "In the embodiment illustrated in FIGS. 1-4 for the round coil two inner mold support bars 18 have been illustrated.", "The ends of the inner mold support bars 18 are connected to spacer bars 20 by bolts 22 , FIG. 3 .", "The annular outer mold 24 , FIGS. 2 and 3, is fabricated into either a round or oval shape and is constructed of 18 gauge or 1.22 mm thick cold rolled steel so as to be disposable.", "The outer mold 24 is of one-piece construction with an integrated dome and tap area 26 .", "The tap or dome area 26 , being an open exposed area of the coil and mold, makes it well suited for the epoxy filling position for the encapsulation process.", "This also serves as a reserve area for make up of any epoxy shrinkage.", "The following is a detailed step by step manufacturing process for construction of a cast coil in accordance with the present invention.", "The sheet metal inner mold 12 is prepared by installing a rubber gasket to the flanges of the mold and securing it by bolting or clamping.", "A liquid silicone sealant preferably is applied to the outside of the mold gasket area and permitted to air dry for a predetermined period.", "It has been found that a minimum of four hours for air drying is suitable and this can take place during the winding process.", "The inner mold 12 is then installed onto an expanding mandrel of a standard winding machine (not shown) and expanded until secure.", "An epoxy release agent preferably is applied to all exposed surfaces of the inner mold 12 in accordance with recommendations of the epoxy manufacturer.", "Apre-pregnated glass netmaterial 28 is applied to the innermold 12 to ensure good surface coverage.", "It is preferable that the glass net be applied with the large strands in the radial direction of the coil.", "Sectional strips may be used on the outer surface of the coil to reduce material content.", "A coil winding 30 is then applied by the winding machine to the inner mold 12 .", "A pre-pregnated glass net 32 is then installed over the finished coil winding 30 to provide an outer layer of glass net which also is preferably applied radially.", "The outer mold 24 is then installed and secured over the finished coil 30 .", "This process may be performed while the inner mold 12 is on the mandrel or it may be performed at a remote assembly site.", "After the coil 30 is removed from the winding equipment, the inner support members 18 are inserted.", "These support members 18 maintain the coil shape on large coils and remain inside the inner mold 12 during the entire encapsulation process.", "Prior to installing the outer mold 24 , an epoxy release agent is applied to the inside of the outer mold 24 .", "For best results continuous and consistent coverage is essential.", "Thereafter, the outer mold 24 is installed over the coil winding 30 .", "A gasket material 34 is placed over the inner and outer disposable mold ends as shown in FIGS. 1 and 4.", "The application of a small amount of suitable adhesive such as super glue to the mold and gasket mating surfaces will aid in securing the gasket 34 to the mold ends.", "A pair of end plates 36 , 36 are set in place against the gasket and mold surfaces and temporarily secured in place while verifying the squareness and positioning ofthe inner and outer molds 12 and 24 .", "A plurality of compression rods 38 are installed to connect the end plates 36 .", "The compression rods 38 have threaded ends for receiving nut members 40 .", "At this point in the process the nut members 40 are not tightened to apply torque to the compression rods 38 .", "A plurality of coil support plates 42 are installed at the top and each end of the mold dome area 26 using small clamps 44 .", "This will support the weight of the coil 30 during the encapsulation and curing processes.", "Torque is now applied to the compression rods 38 by tightening the nut members 40 .", "This is preferably done by starting at one side of the end plates and moving in a crossing sequence until torque values in the order of 130 in lbs.", "to 140 in lbs.", "is established on all of the remaining compression rods 38 .", "Torque values preferably are established by 40 to 50 in.", "lb.", "increments.", "The length of the inner and outer molds 12 and 24 preferably are manufactured to close tolerances in the order of 0.4 mm.", "This is desirable for obtaining consistent gasket sealing to end plates.", "With the process described venting of the innermold area is desirable at the end plates at 36 a for equalization of pressure during the casting process.", "With the casting mold assembly 10 in a horizontal position it is placed in a vacuum chamber and a casting resin 48 , such for example as an epoxy resin, is introduced through the openings in the support plates 42 to fill the mold with the casting resin.", "Such a vacuum casting process is well known in the art.", "It is preferable that the mold assembly 10 be maintained horizontal or level during the gelling and curing process.", "After the curing process has been completed, the outer and inner molds are removed and the encapsulated coil is removed from the casting mold assembly.", "While the present invention has been described in connection with a method of making a round winding configuration in FIGS. 1-4, it is equally applicable to oval winding configurations.", "The principle difference is in the shape of the inner and outer molds.", "An example of a mold assembly for oval shaped coils is illustrated in FIGS. 5 and 6.", "The casting mold assembly 50 shown in FIGS. 5 and 6 includes an oval shaped inner mold 52 and an oval shaped outer mold 54 .", "Both the inner and outer molds 52 and 54 are made of low cost sheet metal similar to the inner and outer molds 12 and 24 illustrated in FIGS. 1-4.", "A glass net material is applied over the inner mold 52 and a coil winding 56 is then applied by the winding machine to the inner mold 52 .", "Another layer of glass net is then installed over the finished coil winding 56 to provide an outer layer of glass net.", "The outer mold 54 is then installed and secured over the finished coil 56 .", "Mechanical strength of the oval coil design requires internal support longitudinally across the coil to maintain shape consistency.", "Typically there are three mechanical supports in the form of disks 58 equally spaced inside the mold, beginning about 4 inches from the end of the mold.", "The mechanical support work pieces may be fabricated on a punch machine to obtain the oval shape.", "The material thickness for the inner support may be 14 gauge (1.88 mm) or 11 gauge (3.17 mm).", "The other parts of the casting mold assembly 50 are similar to the parts of the casting mold assembly 10 and have been identified with similar reference characters with the addition of a prime.", "From the foregoing it will be seen that the present invention includes a new process of winding either round or oval transformer coils over a disposable mold which acts as both a winding mandrel and as an inner mold shell for epoxy encapsulation.", "The invention also includes a simple technique of making the inner and outer molds using low cost sheet metal.", "The invention has many advantages over conventional fixed sized standard winding mandrels and casting molds.", "Two of the features or advantages are the use of low cost sheet metal to form a flexible sized oval or circular mandrel and the horizontal molding concept.", "The complete winding and molding processes can be all conducted on a standard winding machine for either aluminum or copper conductor wound in a layer or disk type format.", "The process of the present invention provides the advantages of flexible round or oval dimensional sizes, flexible and incremental round or oval shapes providing substantially reduced mandrel and molding costs, elimination of costly standard mold storage, elimination of the need for standard winding mandrels, controlled epoxy thickness for increased dielectric strength and reliability, improved manufacturer ability, reduction in epoxy cost, horizontal epoxy casting and facilitates the opportunity to manufacture transformer coils in a round or oval configuration.", "The present process using a disposable integrated winding mandrel represents a substantial improvement over the current state ofthe art which uses precision made standard sized re-usable round shaped mandrels and molds in fixed size increments.", "While a preferred embodiment ofthe present invention has been described and illustrated, it is to be understood that further modifications thereof can be made without departing from the scope of the appended claims." ]
FIELD OF THE INVENTION This invention is related generally to apparatus for extracting samples of liquid from vessels, and in particular to positive-displacement sampling apparatus with an inline valve. BACKGROUND OF THE INVENTION There is a need with many manufacturing operations and processes and within liquid transportation systems to monitor the composition or other properties of the liquid material which is either contained in or flowing within a vessel. Often what is required is to capture a sample of the liquid from within the vessel in order to make the necessary measurements. It is most desirable to be able to capture such samples without interference with or contamination to the processes being monitored. Non-interference with a process is often achieved by ensuring that vessel pressure is maintained throughout the sampling-capturing operation. Further, it is often a requirement that samples be taken at regular and frequent intervals so that reliability, operator safety, and sampler maintenance and longevity are important requirements for such samplers. A number of samplers which are used in such manufacturing or process applications are devices which capture small, discrete samples of liquid. An example of such a sampler is disclosed in U.S. Pat. No. 6,792,818 by Ben E. Jaeger. This positive-displacement sampler includes a plunger having a sample receiving recess and a connecting device which couples the sampler to a vessel at an aperture in the vessel. The sampler is attached to the connecting device, and the connecting device is moveable between a first position placing the sampler into, and a second position taking the sampler out of communication with the aperture. With the connecting device in the first position, the plunger is reciprocated to extend the plunger and its recess through the connecting device and vessel aperture into product in the vessel to receive a product sample in the recess. The plunger is then retracted from the vessel and through the connecting device to deliver the product sample to a collection point. During reciprocation of the plunger, a liquid seal is maintained between the vessel interior and sample collection point, and when the connecting device is moved to the second position, the sampler can be detached from the connecting device for service or repair, without escape of liquid from the vessel through the connecting device. Particularly severe requirements exist for samplers used in applications where the liquid being sampled contains a solid phase. An example of this is in the handling of oil sands in which the liquid may contain bituminous sand, oil, hot water, and possibly clay. The solid phase is the source of abrasive material which creates a particularly difficult operational environment for samplers. The abrasive material can become trapped in regions around seals, particularly when elements within the sampler become misaligned due to, for example, frictional forces during movement of sampler elements, thereby allowing the abrasive material to flow by leakage into areas in which it is not intended to be, causing excessive wear. Also, when seals move past entry and exit interfaces within valves and other elements within a sampler, abrasive material can easily cause the seals to wear far too rapidly, necessitating frequent and costly maintenance on the sampler. The sampler disclosed in U.S. Pat. No. 6,792,818 described above, when applied in applications such as oil sands, operates in a manner in which excessive seal/interface traverses and misalignment are both causes of seal wear. As an example, in the sampling of such abrasive liquids, sampling frequencies may be as high as five samples per hour and may result in seals being replaced as often as once each week, creating an extremely high maintenance cost. Another desirable and intended feature for samplers is the ability to be able to achieve what is termed “double block and bleed” capability, the ability to isolate the sampler from vessel pressure and to verify that such isolation has indeed taken place so that the sampler can be disconnected. If seals are worn and misalignment causes further leakage, the sampler cannot be relied on to achieve the required isolation. The invention disclosed in the '818 patent can exhibit such unwanted behavior when the ball valve, which is “floating” within a set of seals, becomes misaligned and causes leakage of unwanted vessel pressure, thereby causing a potentially unsafe condition for an operator performing maintenance on the sampler or simply taking a sample in the course of regular vessel monitoring. U.S. Pat. No. 5,905,213, also by Ben E. Jaeger, discloses a sampler in which the forward end of the sampler housing is coupled to a movable valve for movement with the valve, and the housing and valve have axially-aligned bores. Movement of the valve places the forward end of its bore into and out of communication with an opening in a vessel containing the liquid to be sampled. A plunger in the housing bore has a sample-receiving recess intermediate its ends, and with the forward end of the valve bore placed into communication with the interior of the vessel, the plunger is reciprocated forward in the housing and valve bores to project the recess into the vessel to receive a product sample therein. The plunger is then reciprocated rearward to retract the product sample containing recess from the vessel and through the valve and housing bores to a sample collection point in the housing. When repair or replacement of the sampler is required, the valve is moved to place the forward end of the valve bore out of communication with the vessel interior, whereupon the sampler housing can be disconnected from the valve without outflow of liquid product from the vessel through the valve bore. A disadvantage of the arrangement is that the entirety of the sampler moves conjointly with movement of the valve between its open and closed positions, so a relatively large unobstructed area must be provided around the sampler to accommodate such movement, which limits freedom of location of the sampling apparatus. In addition, to accommodate mounting of the sampler housing on the valve, the valve must be relatively large to accommodate connection of the sampler housing to it, resulting in increased manufacturing costs. Existing samplers currently used as described above fall short of delivering effective, safe and cost-effective sampling. Thus, there is a need for a sampler which satisfies the objectives as set forth in the following section. OBJECTS OF THE INVENTION It is an object of this invention, in the field of process sampling technology, to provide an improved sampler which incorporates the isolation valve within the sampler apparatus. Another object is to provide a sampler which deposits the liquid sample from a location within the valve of the sampler. Another object of the present invention is to provide a sampler which can be used with abrasive liquids. Another object of this invention is to provide a sampler which minimizes wear on seals within the sampler. Another object of this invention is to provide a sampler which minimizes leakage at the seals within the sampler. Another object of this invention is to provide a sampler with a valve in which valve core is completely encapsulated by its trunnion supports and, further, in which the valve core and stem are structurally integral. Another object of this invention is to provide a sampler which reduces the number of times seals traverse across interfaces within the sampler during the sampling process. A further object of this invention is to provide a sampler which protrudes a reduced length from the vessel and thus also has reduced weight. It is an object of this invention to provide a sampler with “double-block-and-bleed” capability with a single valve. It is also an object of this invention to provide a sampler with improved operator safety. Still another object of the invention is to provide a sample which minimizes misalignment within the valve. Yet another object of the invention is to provide a sampler with a valve which is less sensitive to any misalignment that may occur within the valve. These and other objects of the invention will be apparent from the following descriptions and from the drawings. SUMMARY OF THE INVENTION The invention is an improvement in apparatus for withdrawing a liquid sample from a vessel. Such apparatus is affixed to the vessel and has (a) a plunger forming a sample-receiving space movable from the vessel interior to and beyond a sample-delivery site and (b) a valve for closing the vessel when the plunger is beyond the sample-delivery site. The improvement of the instant invention comprises the sample-delivery site being incorporated in the valve. In some preferred embodiments of the invention, the valve is a trunnion valve and the valve has a stem and a central portion, the central portion dividing the stem into a first stem portion and a second stem portion and having a through-hole with an axis substantially perpendicular to the stem axis. In highly preferred embodiments, the first stem portion includes a discharge/bleed port aligned substantially along the axis of the stem for discharge of the sample from the sample-receiving space when such space is at the sample-delivery site. Further, the plunger in some highly preferred embodiments passes through the through-hole to receive a sample from the vessel interior and to deliver the sample to the discharge/port. In some preferred embodiments, the through-hole in the central portion of the valve is a clearance hole for the plunger, and in some preferred embodiments, the second stem portion includes a purge/flush inlet port. In highly preferred embodiments of the inventive sampling apparatus, the valve includes first and second valve seats that form stem-engagement surfaces for the first and second stem portions, respectively, and that together form a central-portion-engagement surface. In such embodiments, the first and second valve seats together surround, support and seal the central portion and the first and second stem portions. In some embodiments, the plunger moves within first and second axially-aligned plunger cylinders, (a) the first on the vessel side of the valve and the second on the opposite side of the valve, (b) the sample-receiving space is an annular space, and (c) the plunger includes first and second plunger seals each mounted beyond a respective end of the sample-receiving space and spaced such that when the sample-receiving space is at the sample-delivery site, the first and second plunger seals are engaging the first and second plunger cylinders, respectively. In highly preferred embodiments, the valve is a ball valve. In other embodiments, the valve is a plug valve. Further, some embodiments include a compound actuator for plunger movement. Highly preferred embodiments of the inventive sampling apparatus include a bleed valve to effect collection of the sample from the discharge/bleed port. The term “liquid” as used herein, in addition to the common usage of the term, also includes liquids which contain a solid phase, such as is the case with a mixture of oil, water and sand. The term “vessel” as used herein refers to any sort of enclosure containing the liquid which is to be sampled. Thus, a vessel as so defined includes a pipe or other conduit through which the liquid flows as well as any container such as a process reactor which is holding the liquid to be sampled. The term “clearance hole” as used herein refers to a hole which is sized such that the object which is referenced thereto is able to pass through or be contained in the hole without touching the walls of the hole. The term “sample withdrawal” or related terminology as used herein refers to the process by which a sample of liquid is removed from a vessel and subsequently delivered to a desired sample location. The term “compound actuator” as used herein refers to a pneumatic or hydraulic actuator (containing a primary piston and a cylinder) which also contains a secondary piston such that the primary and secondary pistons cooperate to effect the movement of the object being moved by the actuator. BRIEF DESCRIPTION OF THE DRAWINGS The drawings illustrate preferred embodiments which include the above-noted characteristics and features of the invention. The invention will be readily understood from the descriptions and drawings. In the drawings: FIG. 1 is a perspective drawing of one embodiment of the inventive sampling apparatus. FIG. 2 is a cutaway perspective drawing of the sampling apparatus of FIG. 1 with the sample-receiving space between the vessel interior and the sample-delivery site and within the front sleeve. FIG. 3 is a cutaway perspective drawing of the sampling apparatus of FIG. 1 with the sample-receiving space in the vessel interior. FIG. 4 is a cutaway perspective drawing of the sampling apparatus of FIG. 1 with the sample-receiving space at the sample-delivery site. FIG. 5 is a cutaway perspective drawing of the sampling apparatus of FIG. 1 with the sample-receiving space beyond the sample-receiving site and with the ball valve in a closed position. FIG. 6 is a cutaway perspective drawing of the plunger of the sampling apparatus of FIG. 1 . FIG. 7 is a cutaway perspective drawing of the sampling apparatus of FIG. 1 with the valve portion and the actuator portion separated for maintenance. FIG. 8 is a cutaway perspective drawing of the valve of the sampling apparatus of FIG. 1 , the plane of the cutaway being perpendicular to the cutaway plane of FIGS. 2-5 . The valve is in a closed position, and the bleed valve is in a closed position. FIG. 9 is a cutaway perspective drawing of the valve of the sampling apparatus of FIG. 8 with the valve in an open position, and the bleed valve is in an open position. FIG. 10A is a cross-sectional drawing of the stem, central portion and the seat of a ball valve. FIG. 10B is a cutaway perspective drawing of a seat for the ball valve of FIG. 9 a. FIG. 10C is a cross-sectional drawing of the stem and central portion and the seat of a plug valve. The central portion is a truncated cone. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 is a perspective drawing of sampling apparatus 10 . FIGS. 2-5 and 7 - 9 are all cutaway perspective drawings of sampling apparatus 10 with the elements of apparatus 10 in different positions illustrating its operation. (To reduce the crowding of reference numbers, not all elements of sampling apparatus 10 are labeled in every figure.) Referring to FIGS. 1-5 , sampling apparatus 10 has a valve portion 12 and an actuator portion 14 . Sampling apparatus 10 is affixed by adapter 16 to a vessel 1 (shown in FIGS. 2-5 ) which contains the liquid (not shown) to be sampled through an adapter opening 18 (shown in FIGS. 2-5 ). Sampling apparatus 10 also includes a bleed valve 20 attached to valve portion 12 for the purpose of assisting in the collection of a sample taken by sampling apparatus 10 . Referring now to FIGS. 2-5 and FIGS. 8-9 , valve portion 12 of sampling apparatus 10 includes valve 11 which has a valve body 22 containing a valve stem 24 and a central valve portion 26 . Stem 24 is divided into two portions, a first stem portion 24 a and a second stem portion 24 b, by central valve portion 26 , thus forming the stem and central valve portion of a trunnion valve. Central valve portion 26 is a spherical structure and has a through-hole 26 h (best seen in FIGS. 5 , 8 and 9 ) with an axis substantially perpendicular to the axis of stem 24 ; thus valve 11 in this embodiment is a ball valve. Through-hole 26 h forms the sample-delivery site of sampling apparatus 10 . FIGS. 10A and 10B more clearly illustrate some of the details of stem 24 and central portion 26 . Stem 24 and central portion 26 are surrounded, supported and sealed by a first valve seat 28 a and a second valve seat 28 b. First and second valve seats 28 a and 28 b engage first and second stem portions 28 a and 28 b respectively at first and second stem-engagement surfaces 30 a and 30 b and together engage central portion 26 at a central-portion-engagement surface 30 c. First and second valve seats 28 a and 28 b thus ensure that stem 24 and central valve portion 26 remain in proper alignment within valve 11 . Referring now to FIGS. 8 and 9 for further detail with respect to valve portion 12 , first stem portion is partially supported by valve body 22 at a support surface 32 and by a set of gland seals 34 s. Primary support for stem 24 and central portion is provided by seats 28 a and 28 b. First and second stem-engagement surfaces 30 a and 30 b thus form trunnion supports for first and second stem portions 24 a and 24 b within valve 11 . Gland 34 is held in place by a bevel washer spring 36 , and a packing bolt 38 is tightened into a threaded portion 40 of valve body 22 to complete the internal assembly of valve 11 . Valve handle 42 is attached to stem 24 to effect turning of valve 11 . First stem portion 24 a includes an axially-aligned sample discharge/bleed port 44 . Port 44 is open to through-hole 26 h, the sample-delivery site, thus enabling sample liquid to flow through first stem portion 24 a into bleed valve 20 and, as desired, into a collection container (not shown) which may be connected to bleed valve sample port 54 . Second stem portion 24 b includes a purge/flush inlet port 46 . Port 46 includes axial passage 46 a and intersecting passage 46 b. Passage 46 a is aligned axially with stem 24 , and passage 46 b intersects passage 46 a in order to enable flow in port 46 to reach a pair of annular gland passages 48 a and 48 b which are connected together by a connecting passage 50 . Annular gland passage 48 b is aligned with an external flush port 52 (shown on FIGS. 1 , 8 and 9 ). Thus, a flow passage exists in valve 11 between port 52 and through-hole 26 h to effect purging and flushing of valve 11 regardless of the position of stem 24 of valve 11 . FIG. 6 is a cutaway perspective drawing of a plunger 60 of sampling apparatus 10 . The various elements of plunger 60 can be seen in FIGS. 2-5 but are most easily seen in FIG. 6 . Plunger 60 is assembled from a number of plunger elements. Plunger 60 includes a plunger tube 62 welded to plunger adapter 64 at one end of tube 62 and a rear piston 63 welded at the other end of tube 62 . Adapter 64 includes a threaded hole 65 into which a mandrel 66 is inserted. Rear piston 63 includes rear piston seals 63 a and 63 b. Mandrel 66 includes a mandrel head 66 a and a mandrel shaft 66 b. Onto mandrel 66 are assembled, in sequence, a front seal 68 a, an O-ring 74 (all O-rings in this assembly are labeled with reference number 74 as similar elements), an annular spacer 70 , an O-ring 74 , a middle seal 68 b, an O-ring 74 , and a rear spacer 72 . Annular spacer 70 forms the sample-receiving space of sampling apparatus 10 . A rear seal 68 c is placed onto plunger adapter 64 , and mandrel 66 is inserted into threaded hole 65 in adapter 64 , completing the assembly of plunger 60 . Mandrel 66 is thus configured to enable easy disassembly and assembly to facilitate replacement of the seals on plunger 60 . Referring again to FIGS. 2-5 , plunger 60 is slidably assembled into a rear sleeve 76 which is connected to valve body 22 . Plunger 60 slides within sleeve 76 , through through-hole 26 h when stem 24 is in position to allow plunger 60 to enter hole through-hole 26 h, and into and partially through a front sleeve 78 mounted in adapter 16 and body 22 . O-rings 80 provide seals for plunger 60 within front sleeve 78 as shown. Rear sleeve 76 and front sleeve 78 form a pair of first and second axially-aligned plunger cylinders in which plunger 60 moves. The first plunger cylinder, front sleeve 78 is on the vessel side of valve 11 , and the second plunger cylinder, rear sleeve 76 , is on the opposite side of valve 11 . A front piston 82 is slidably assembled onto the outside of rear sleeve 76 , into a front cylinder 84 , and into a rear cylinder 86 such that front piston 82 slides within both front cylinder 84 and rear cylinder 86 . Rear piston 63 of plunger 60 is also slidably assembled into rear cylinder 86 . Front piston 82 includes a forward piston portion 82 a and an aft piston portion 82 b. Aft portion 82 b includes a front piston sleeve bearing 88 in which plunger 60 slides, and rear sleeve 76 includes two rear sleeve seals 76 a and 76 b between which is an annular slot 92 connected to an intermediate drain/vent port 94 open to the outside of valve 11 . The purpose of slot 92 and port 94 is that if seal 76 a were to leak, liquid from sampling apparatus 10 would not find its way into rear cylinder 86 but rather simply flow through port 94 to the outside. Forward piston portion 82 a includes two seals 85 a and 85 b for slidable support of front piston 82 within front cylinder 84 . Front cylinder 84 includes a center head 90 which forms the connection between front cylinder 84 and rear cylinder 86 . Aft piston portion 82 b includes an air passage 83 to allow air flow through aft piston portion 82 b when front piston 82 is sliding with respect to rear sleeve 76 . Rear cylinder 86 includes a rear head 95 which closes off rear cylinder 86 . Rear head 95 includes seals 96 which seal between rear head 95 and a stop tube 98 assembled into a threaded hole 100 in rear head 95 with a wing nut 102 . Stop tube 98 functions to provide an air passage for displaced air when plunger 60 moves within rear cylinder 86 . Stop tube 98 with a stop washer 99 mounted thereon also functions as a stop for plunger 60 as described below. Front piston 82 , front cylinder 84 , rear piston 63 and rear cylinder 86 , with their attendant seals, constitute a compound pneumatic actuator for effecting the movement of plunger 60 into the various positions required by sampling apparatus 10 . Plunger 60 could be actuated by numerous other types of actuators including but not limited to simple pneumatic actuators, hydraulic actuators, and various electromechanical actuators. FIGS. 2-5 illustrate four different positions of the plunger within sampling apparatus 60 . These four positions constitute the specific positions which best describe the process of liquid sample withdrawal from vessel 1 . Actuator portion 14 of sampling apparatus 10 moves plunger 60 to and from the various positions in order to effect sample withdrawal. FIG. 6 illustrates sampling apparatus 10 separated into valve portion 12 and actuator portion 14 . In FIG. 6 , wing nut 102 has been unscrewed to release stop tube 98 , placing plunger 60 in a maintenance position. In this position, stop tube 98 can be used to push mandrel 66 out of rear sleeve 76 , making it available for removal and replacement of seals 68 a - 68 c as required or any other maintenance which may be required. FIG. 2 illustrates plunger 60 of sampling apparatus is the “parked” position, a position placing mandrel head 66 a in a position to protect front sleeve 78 and mandrel head 66 a from damage caused by abrasive liquid flowing in vessel 1 . In this position, front piston 82 has been moved away from valve 11 to a position stopped by center head 90 . To reach this position, actuator air is applied to a piston-park port 108 causing front piston 82 to move away from valve 11 . Center head 90 provides a stopping position for front piston 82 which serves as a stop for rear piston 63 . FIG. 3 illustrates plunger 60 of sampling apparatus 10 in position to receive a liquid sample from within vessel 1 . Valve stem 24 is in position to align through-hole 26 h such that plunger 60 may pass through central valve portion 26 . In this sample-receiving position, the sample-receiving site formed within annular spacer 70 is open to capture liquid flowing through or being processed within vessel 1 . In this position, both front piston 82 and rear piston 63 are positioned as close to valve 11 as possible within their respective cylinders. To reach this position, actuator air is applied to a piston-apply port 104 causing pistons 63 and 82 to move toward valve 11 . From the sample-receiving position, the fixed volume of liquid in the sample-receiving space is then moved through adapter opening 18 and through front sleeve 78 into through-hole 26 h which forms the sample-delivery site. This sample-delivery position of sampling apparatus 10 is illustrated in FIG. 4 . In the sample-delivery position, rear piston 63 is moved within rear cylinder 86 until it reaches stop washer 99 on stop tube 98 . Stop washer 99 is positioned to place annular spacer 70 in the sample-delivery site within through-hole 26 h in central valve portion 26 . To reach this sample-delivery position, actuator air is applied to piston-retract port 106 to move rear piston 63 to its stop position created by stop washer 99 . In the sample-delivery position, bleed valve 20 can be used to effect transfer of the liquid sample contained in the sample-receiving space to a sample container (not shown) which may be connected to bleed valve 20 at bleed valve sample port 54 . FIG. 8 illustrates bleed valve 20 , a ball valve in this embodiment, in the closed position while sampling apparatus also in a closed position, indicating that sampling apparatus 10 is in a position ready for or undergoing maintenance as illustrated in FIGS. 5 and 6 , respectively. FIG. 9 illustrates bleed valve 20 in an open position with valve 11 also in an open position, thereby allowing a liquid sample to pass from the sample-delivery site in through-hole 26 h, through bleed valve 20 and into a sample container (not shown). Bleed valve 20 is attached to first stem portion 24 a such that when valve 11 is turned using valve handle 42 , the entire bleed valve 20 turns with stem 24 . FIG. 5 illustrates sampling apparatus in a maintenance position, ready for separation of actuator portion 14 from valve portion 12 as illustrated in FIG. 6 . To reach this position, wing nut 102 is removed from rear head 95 thereby allowing stop tube to move stop washer 99 away from valve 11 and thus allowing plunger 60 to be removed from valve 11 completely. With the stop washer 99 back against rear head 95 , actuator air applied to piston-retract port 106 causes rear piston to move farther back into rear cylinder 86 . A position called a “double-block-and-bleed” position is illustrated in FIG. 5 . With sampling apparatus in a position ready for maintenance, an operator is able to use external flush port 52 in combination with bleed valve 20 to ensure that valve 11 has been properly closed, thus isolating vessel 1 from sampling apparatus 10 , before sampling apparatus 10 is removed. In this position, it is also possible to ensure that the sample has been properly removed from the sample-delivery site in through-hole 26 h. This position of sampling apparatus 10 thus provides safety for the operator during operation of sampling apparatus 10 . The selection of materials to be used for the embodiment described herein follows sound engineering practice as known by those skilled in the state-of-the-art of process monitoring, chemical instrument design or mechanical design. In general, parts within the embodiment described herein may be made of stainless steel such as 316SS but are not limited to being made of stainless steel. Seal materials for O-rings can be but are not limited to commercially-available O-ring materials such as Viton® or nitrile, both known to those skilled in the art of mechanical design. Seals such as rear sleeve seals 76 a and 76 b may be made of PTFE (polytetrafluoroethylene) well known to those skilled in the art of mechanical design. Valve seats 28 a and 28 b may be made of TFM™, a modified PTFE material also well known to those skilled in the art of mechanical design. In some applications, front sleeve 78 may be required to withstand an highly-abrasive environment. In such cases, it may be useful to make front sleeve 78 from a material such as tungsten carbide. This and other materials are well-known to those skilled in the art of mechanical design. Front piston sleeve bearing 88 may be made of an appropriate sleeve bearing material such as silicon bronze or an oil- or PTFE-impregnated bearing material such as is well-known by those skilled in the art of mechanical design. Front piston 82 , front cylinder 84 , rear piston 63 , rear cylinder 86 , center head 90 , and rear head 95 all may be made out of aluminum. None of material suggested herein are meant to be limiting to the scope of the present invention. FIG. 10C illustrates an alternative embodiment for stem 24 and central valve portion 26 . In FIG. 10C , central valve portion 26 is a truncated cone; a large end 26 a of conical central valve portion 26 is adjacent to second stem portion 24 b and a small end 26 b of conical central valve portion 26 is adjacent to first stem portion 24 a. Referring to FIG. 3 , when, for example, front seal 68 a on mandrel head 66 of plunger 60 enters front sleeve 78 from vessel 1 , seal 68 a moves across a boundary between being unconstrained and being constrained (fitting tightly) within front sleeve 78 . Such a transition is called a seal/interface encounter. Each such encounter is an opportunity for any abrasive solid phase in the liquid from vessel 1 that is carried by the seal to cause wear of the seals. One significant advantage of placing the sample-delivery site within valve 11 is that there are fewer such encounters during a sample withdrawal cycle than with sampling apparatus of the prior art such as that described in U.S. Pat. No. 6,792,818 mentioned above. If the sample-receiving space was moved to a sample-delivery site on the side of valve opposite to vessel 1 as in Jaeger '818, several additional wear-causing encounters would occur, thereby reducing the life of the seals as compared to those in the present invention. Furthermore, through-hole 26 h is a clearance hole, i.e., larger in inside diameter compared to the outside diameters of front seal 68 a, middle seal 68 b, and rear seal 68 c on mandrel 66 such that these seals do not touch the walls of through-hole 26 h and such that any solid phase particles in the liquid being sample will not be pressed into these seals while sampling apparatus 10 is the sample-delivery position. In spite of the fact that first and second valve seats 28 a and 28 b ensure that stem 24 and central valve portion 26 remain in proper alignment within valve 11 , through-hole 26 h, being a clearance hole, also reduces the effect of any misalignment which may occur within valve 11 during the operation of sampling apparatus 10 . While the principles of this invention have been described in connection with specific embodiments, it should be understood clearly that these descriptions are made only by way of example and are not intended to limit the scope of the invention.
Apparatus for withdrawing a liquid sample from a vessel, the apparatus affixed to the vessel and having (a) a plunger forming a sample-receiving space movable from the vessel interior to and beyond a sample-delivery site, and (b) a valve for closing the vessel when the plunger is beyond the sample-delivery site. In the sampling apparatus, the sample-delivery site is incorporated in the valve.
Analyze the document's illustrations and descriptions to summarize the main idea's core structure and function.
[ "FIELD OF THE INVENTION This invention is related generally to apparatus for extracting samples of liquid from vessels, and in particular to positive-displacement sampling apparatus with an inline valve.", "BACKGROUND OF THE INVENTION There is a need with many manufacturing operations and processes and within liquid transportation systems to monitor the composition or other properties of the liquid material which is either contained in or flowing within a vessel.", "Often what is required is to capture a sample of the liquid from within the vessel in order to make the necessary measurements.", "It is most desirable to be able to capture such samples without interference with or contamination to the processes being monitored.", "Non-interference with a process is often achieved by ensuring that vessel pressure is maintained throughout the sampling-capturing operation.", "Further, it is often a requirement that samples be taken at regular and frequent intervals so that reliability, operator safety, and sampler maintenance and longevity are important requirements for such samplers.", "A number of samplers which are used in such manufacturing or process applications are devices which capture small, discrete samples of liquid.", "An example of such a sampler is disclosed in U.S. Pat. No. 6,792,818 by Ben E. Jaeger.", "This positive-displacement sampler includes a plunger having a sample receiving recess and a connecting device which couples the sampler to a vessel at an aperture in the vessel.", "The sampler is attached to the connecting device, and the connecting device is moveable between a first position placing the sampler into, and a second position taking the sampler out of communication with the aperture.", "With the connecting device in the first position, the plunger is reciprocated to extend the plunger and its recess through the connecting device and vessel aperture into product in the vessel to receive a product sample in the recess.", "The plunger is then retracted from the vessel and through the connecting device to deliver the product sample to a collection point.", "During reciprocation of the plunger, a liquid seal is maintained between the vessel interior and sample collection point, and when the connecting device is moved to the second position, the sampler can be detached from the connecting device for service or repair, without escape of liquid from the vessel through the connecting device.", "Particularly severe requirements exist for samplers used in applications where the liquid being sampled contains a solid phase.", "An example of this is in the handling of oil sands in which the liquid may contain bituminous sand, oil, hot water, and possibly clay.", "The solid phase is the source of abrasive material which creates a particularly difficult operational environment for samplers.", "The abrasive material can become trapped in regions around seals, particularly when elements within the sampler become misaligned due to, for example, frictional forces during movement of sampler elements, thereby allowing the abrasive material to flow by leakage into areas in which it is not intended to be, causing excessive wear.", "Also, when seals move past entry and exit interfaces within valves and other elements within a sampler, abrasive material can easily cause the seals to wear far too rapidly, necessitating frequent and costly maintenance on the sampler.", "The sampler disclosed in U.S. Pat. No. 6,792,818 described above, when applied in applications such as oil sands, operates in a manner in which excessive seal/interface traverses and misalignment are both causes of seal wear.", "As an example, in the sampling of such abrasive liquids, sampling frequencies may be as high as five samples per hour and may result in seals being replaced as often as once each week, creating an extremely high maintenance cost.", "Another desirable and intended feature for samplers is the ability to be able to achieve what is termed “double block and bleed”", "capability, the ability to isolate the sampler from vessel pressure and to verify that such isolation has indeed taken place so that the sampler can be disconnected.", "If seals are worn and misalignment causes further leakage, the sampler cannot be relied on to achieve the required isolation.", "The invention disclosed in the '818 patent can exhibit such unwanted behavior when the ball valve, which is “floating”", "within a set of seals, becomes misaligned and causes leakage of unwanted vessel pressure, thereby causing a potentially unsafe condition for an operator performing maintenance on the sampler or simply taking a sample in the course of regular vessel monitoring.", "U.S. Pat. No. 5,905,213, also by Ben E. Jaeger, discloses a sampler in which the forward end of the sampler housing is coupled to a movable valve for movement with the valve, and the housing and valve have axially-aligned bores.", "Movement of the valve places the forward end of its bore into and out of communication with an opening in a vessel containing the liquid to be sampled.", "A plunger in the housing bore has a sample-receiving recess intermediate its ends, and with the forward end of the valve bore placed into communication with the interior of the vessel, the plunger is reciprocated forward in the housing and valve bores to project the recess into the vessel to receive a product sample therein.", "The plunger is then reciprocated rearward to retract the product sample containing recess from the vessel and through the valve and housing bores to a sample collection point in the housing.", "When repair or replacement of the sampler is required, the valve is moved to place the forward end of the valve bore out of communication with the vessel interior, whereupon the sampler housing can be disconnected from the valve without outflow of liquid product from the vessel through the valve bore.", "A disadvantage of the arrangement is that the entirety of the sampler moves conjointly with movement of the valve between its open and closed positions, so a relatively large unobstructed area must be provided around the sampler to accommodate such movement, which limits freedom of location of the sampling apparatus.", "In addition, to accommodate mounting of the sampler housing on the valve, the valve must be relatively large to accommodate connection of the sampler housing to it, resulting in increased manufacturing costs.", "Existing samplers currently used as described above fall short of delivering effective, safe and cost-effective sampling.", "Thus, there is a need for a sampler which satisfies the objectives as set forth in the following section.", "OBJECTS OF THE INVENTION It is an object of this invention, in the field of process sampling technology, to provide an improved sampler which incorporates the isolation valve within the sampler apparatus.", "Another object is to provide a sampler which deposits the liquid sample from a location within the valve of the sampler.", "Another object of the present invention is to provide a sampler which can be used with abrasive liquids.", "Another object of this invention is to provide a sampler which minimizes wear on seals within the sampler.", "Another object of this invention is to provide a sampler which minimizes leakage at the seals within the sampler.", "Another object of this invention is to provide a sampler with a valve in which valve core is completely encapsulated by its trunnion supports and, further, in which the valve core and stem are structurally integral.", "Another object of this invention is to provide a sampler which reduces the number of times seals traverse across interfaces within the sampler during the sampling process.", "A further object of this invention is to provide a sampler which protrudes a reduced length from the vessel and thus also has reduced weight.", "It is an object of this invention to provide a sampler with “double-block-and-bleed”", "capability with a single valve.", "It is also an object of this invention to provide a sampler with improved operator safety.", "Still another object of the invention is to provide a sample which minimizes misalignment within the valve.", "Yet another object of the invention is to provide a sampler with a valve which is less sensitive to any misalignment that may occur within the valve.", "These and other objects of the invention will be apparent from the following descriptions and from the drawings.", "SUMMARY OF THE INVENTION The invention is an improvement in apparatus for withdrawing a liquid sample from a vessel.", "Such apparatus is affixed to the vessel and has (a) a plunger forming a sample-receiving space movable from the vessel interior to and beyond a sample-delivery site and (b) a valve for closing the vessel when the plunger is beyond the sample-delivery site.", "The improvement of the instant invention comprises the sample-delivery site being incorporated in the valve.", "In some preferred embodiments of the invention, the valve is a trunnion valve and the valve has a stem and a central portion, the central portion dividing the stem into a first stem portion and a second stem portion and having a through-hole with an axis substantially perpendicular to the stem axis.", "In highly preferred embodiments, the first stem portion includes a discharge/bleed port aligned substantially along the axis of the stem for discharge of the sample from the sample-receiving space when such space is at the sample-delivery site.", "Further, the plunger in some highly preferred embodiments passes through the through-hole to receive a sample from the vessel interior and to deliver the sample to the discharge/port.", "In some preferred embodiments, the through-hole in the central portion of the valve is a clearance hole for the plunger, and in some preferred embodiments, the second stem portion includes a purge/flush inlet port.", "In highly preferred embodiments of the inventive sampling apparatus, the valve includes first and second valve seats that form stem-engagement surfaces for the first and second stem portions, respectively, and that together form a central-portion-engagement surface.", "In such embodiments, the first and second valve seats together surround, support and seal the central portion and the first and second stem portions.", "In some embodiments, the plunger moves within first and second axially-aligned plunger cylinders, (a) the first on the vessel side of the valve and the second on the opposite side of the valve, (b) the sample-receiving space is an annular space, and (c) the plunger includes first and second plunger seals each mounted beyond a respective end of the sample-receiving space and spaced such that when the sample-receiving space is at the sample-delivery site, the first and second plunger seals are engaging the first and second plunger cylinders, respectively.", "In highly preferred embodiments, the valve is a ball valve.", "In other embodiments, the valve is a plug valve.", "Further, some embodiments include a compound actuator for plunger movement.", "Highly preferred embodiments of the inventive sampling apparatus include a bleed valve to effect collection of the sample from the discharge/bleed port.", "The term “liquid”", "as used herein, in addition to the common usage of the term, also includes liquids which contain a solid phase, such as is the case with a mixture of oil, water and sand.", "The term “vessel”", "as used herein refers to any sort of enclosure containing the liquid which is to be sampled.", "Thus, a vessel as so defined includes a pipe or other conduit through which the liquid flows as well as any container such as a process reactor which is holding the liquid to be sampled.", "The term “clearance hole”", "as used herein refers to a hole which is sized such that the object which is referenced thereto is able to pass through or be contained in the hole without touching the walls of the hole.", "The term “sample withdrawal”", "or related terminology as used herein refers to the process by which a sample of liquid is removed from a vessel and subsequently delivered to a desired sample location.", "The term “compound actuator”", "as used herein refers to a pneumatic or hydraulic actuator (containing a primary piston and a cylinder) which also contains a secondary piston such that the primary and secondary pistons cooperate to effect the movement of the object being moved by the actuator.", "BRIEF DESCRIPTION OF THE DRAWINGS The drawings illustrate preferred embodiments which include the above-noted characteristics and features of the invention.", "The invention will be readily understood from the descriptions and drawings.", "In the drawings: FIG. 1 is a perspective drawing of one embodiment of the inventive sampling apparatus.", "FIG. 2 is a cutaway perspective drawing of the sampling apparatus of FIG. 1 with the sample-receiving space between the vessel interior and the sample-delivery site and within the front sleeve.", "FIG. 3 is a cutaway perspective drawing of the sampling apparatus of FIG. 1 with the sample-receiving space in the vessel interior.", "FIG. 4 is a cutaway perspective drawing of the sampling apparatus of FIG. 1 with the sample-receiving space at the sample-delivery site.", "FIG. 5 is a cutaway perspective drawing of the sampling apparatus of FIG. 1 with the sample-receiving space beyond the sample-receiving site and with the ball valve in a closed position.", "FIG. 6 is a cutaway perspective drawing of the plunger of the sampling apparatus of FIG. 1 .", "FIG. 7 is a cutaway perspective drawing of the sampling apparatus of FIG. 1 with the valve portion and the actuator portion separated for maintenance.", "FIG. 8 is a cutaway perspective drawing of the valve of the sampling apparatus of FIG. 1 , the plane of the cutaway being perpendicular to the cutaway plane of FIGS. 2-5 .", "The valve is in a closed position, and the bleed valve is in a closed position.", "FIG. 9 is a cutaway perspective drawing of the valve of the sampling apparatus of FIG. 8 with the valve in an open position, and the bleed valve is in an open position.", "FIG. 10A is a cross-sectional drawing of the stem, central portion and the seat of a ball valve.", "FIG. 10B is a cutaway perspective drawing of a seat for the ball valve of FIG. 9 a. FIG. 10C is a cross-sectional drawing of the stem and central portion and the seat of a plug valve.", "The central portion is a truncated cone.", "DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 is a perspective drawing of sampling apparatus 10 .", "FIGS. 2-5 and 7 - 9 are all cutaway perspective drawings of sampling apparatus 10 with the elements of apparatus 10 in different positions illustrating its operation.", "(To reduce the crowding of reference numbers, not all elements of sampling apparatus 10 are labeled in every figure.) Referring to FIGS. 1-5 , sampling apparatus 10 has a valve portion 12 and an actuator portion 14 .", "Sampling apparatus 10 is affixed by adapter 16 to a vessel 1 (shown in FIGS. 2-5 ) which contains the liquid (not shown) to be sampled through an adapter opening 18 (shown in FIGS. 2-5 ).", "Sampling apparatus 10 also includes a bleed valve 20 attached to valve portion 12 for the purpose of assisting in the collection of a sample taken by sampling apparatus 10 .", "Referring now to FIGS. 2-5 and FIGS. 8-9 , valve portion 12 of sampling apparatus 10 includes valve 11 which has a valve body 22 containing a valve stem 24 and a central valve portion 26 .", "Stem 24 is divided into two portions, a first stem portion 24 a and a second stem portion 24 b, by central valve portion 26 , thus forming the stem and central valve portion of a trunnion valve.", "Central valve portion 26 is a spherical structure and has a through-hole 26 h (best seen in FIGS. 5 , 8 and 9 ) with an axis substantially perpendicular to the axis of stem 24 ;", "thus valve 11 in this embodiment is a ball valve.", "Through-hole 26 h forms the sample-delivery site of sampling apparatus 10 .", "FIGS. 10A and 10B more clearly illustrate some of the details of stem 24 and central portion 26 .", "Stem 24 and central portion 26 are surrounded, supported and sealed by a first valve seat 28 a and a second valve seat 28 b. First and second valve seats 28 a and 28 b engage first and second stem portions 28 a and 28 b respectively at first and second stem-engagement surfaces 30 a and 30 b and together engage central portion 26 at a central-portion-engagement surface 30 c. First and second valve seats 28 a and 28 b thus ensure that stem 24 and central valve portion 26 remain in proper alignment within valve 11 .", "Referring now to FIGS. 8 and 9 for further detail with respect to valve portion 12 , first stem portion is partially supported by valve body 22 at a support surface 32 and by a set of gland seals 34 s. Primary support for stem 24 and central portion is provided by seats 28 a and 28 b. First and second stem-engagement surfaces 30 a and 30 b thus form trunnion supports for first and second stem portions 24 a and 24 b within valve 11 .", "Gland 34 is held in place by a bevel washer spring 36 , and a packing bolt 38 is tightened into a threaded portion 40 of valve body 22 to complete the internal assembly of valve 11 .", "Valve handle 42 is attached to stem 24 to effect turning of valve 11 .", "First stem portion 24 a includes an axially-aligned sample discharge/bleed port 44 .", "Port 44 is open to through-hole 26 h, the sample-delivery site, thus enabling sample liquid to flow through first stem portion 24 a into bleed valve 20 and, as desired, into a collection container (not shown) which may be connected to bleed valve sample port 54 .", "Second stem portion 24 b includes a purge/flush inlet port 46 .", "Port 46 includes axial passage 46 a and intersecting passage 46 b. Passage 46 a is aligned axially with stem 24 , and passage 46 b intersects passage 46 a in order to enable flow in port 46 to reach a pair of annular gland passages 48 a and 48 b which are connected together by a connecting passage 50 .", "Annular gland passage 48 b is aligned with an external flush port 52 (shown on FIGS. 1 , 8 and 9 ).", "Thus, a flow passage exists in valve 11 between port 52 and through-hole 26 h to effect purging and flushing of valve 11 regardless of the position of stem 24 of valve 11 .", "FIG. 6 is a cutaway perspective drawing of a plunger 60 of sampling apparatus 10 .", "The various elements of plunger 60 can be seen in FIGS. 2-5 but are most easily seen in FIG. 6 .", "Plunger 60 is assembled from a number of plunger elements.", "Plunger 60 includes a plunger tube 62 welded to plunger adapter 64 at one end of tube 62 and a rear piston 63 welded at the other end of tube 62 .", "Adapter 64 includes a threaded hole 65 into which a mandrel 66 is inserted.", "Rear piston 63 includes rear piston seals 63 a and 63 b. Mandrel 66 includes a mandrel head 66 a and a mandrel shaft 66 b. Onto mandrel 66 are assembled, in sequence, a front seal 68 a, an O-ring 74 (all O-rings in this assembly are labeled with reference number 74 as similar elements), an annular spacer 70 , an O-ring 74 , a middle seal 68 b, an O-ring 74 , and a rear spacer 72 .", "Annular spacer 70 forms the sample-receiving space of sampling apparatus 10 .", "A rear seal 68 c is placed onto plunger adapter 64 , and mandrel 66 is inserted into threaded hole 65 in adapter 64 , completing the assembly of plunger 60 .", "Mandrel 66 is thus configured to enable easy disassembly and assembly to facilitate replacement of the seals on plunger 60 .", "Referring again to FIGS. 2-5 , plunger 60 is slidably assembled into a rear sleeve 76 which is connected to valve body 22 .", "Plunger 60 slides within sleeve 76 , through through-hole 26 h when stem 24 is in position to allow plunger 60 to enter hole through-hole 26 h, and into and partially through a front sleeve 78 mounted in adapter 16 and body 22 .", "O-rings 80 provide seals for plunger 60 within front sleeve 78 as shown.", "Rear sleeve 76 and front sleeve 78 form a pair of first and second axially-aligned plunger cylinders in which plunger 60 moves.", "The first plunger cylinder, front sleeve 78 is on the vessel side of valve 11 , and the second plunger cylinder, rear sleeve 76 , is on the opposite side of valve 11 .", "A front piston 82 is slidably assembled onto the outside of rear sleeve 76 , into a front cylinder 84 , and into a rear cylinder 86 such that front piston 82 slides within both front cylinder 84 and rear cylinder 86 .", "Rear piston 63 of plunger 60 is also slidably assembled into rear cylinder 86 .", "Front piston 82 includes a forward piston portion 82 a and an aft piston portion 82 b. Aft portion 82 b includes a front piston sleeve bearing 88 in which plunger 60 slides, and rear sleeve 76 includes two rear sleeve seals 76 a and 76 b between which is an annular slot 92 connected to an intermediate drain/vent port 94 open to the outside of valve 11 .", "The purpose of slot 92 and port 94 is that if seal 76 a were to leak, liquid from sampling apparatus 10 would not find its way into rear cylinder 86 but rather simply flow through port 94 to the outside.", "Forward piston portion 82 a includes two seals 85 a and 85 b for slidable support of front piston 82 within front cylinder 84 .", "Front cylinder 84 includes a center head 90 which forms the connection between front cylinder 84 and rear cylinder 86 .", "Aft piston portion 82 b includes an air passage 83 to allow air flow through aft piston portion 82 b when front piston 82 is sliding with respect to rear sleeve 76 .", "Rear cylinder 86 includes a rear head 95 which closes off rear cylinder 86 .", "Rear head 95 includes seals 96 which seal between rear head 95 and a stop tube 98 assembled into a threaded hole 100 in rear head 95 with a wing nut 102 .", "Stop tube 98 functions to provide an air passage for displaced air when plunger 60 moves within rear cylinder 86 .", "Stop tube 98 with a stop washer 99 mounted thereon also functions as a stop for plunger 60 as described below.", "Front piston 82 , front cylinder 84 , rear piston 63 and rear cylinder 86 , with their attendant seals, constitute a compound pneumatic actuator for effecting the movement of plunger 60 into the various positions required by sampling apparatus 10 .", "Plunger 60 could be actuated by numerous other types of actuators including but not limited to simple pneumatic actuators, hydraulic actuators, and various electromechanical actuators.", "FIGS. 2-5 illustrate four different positions of the plunger within sampling apparatus 60 .", "These four positions constitute the specific positions which best describe the process of liquid sample withdrawal from vessel 1 .", "Actuator portion 14 of sampling apparatus 10 moves plunger 60 to and from the various positions in order to effect sample withdrawal.", "FIG. 6 illustrates sampling apparatus 10 separated into valve portion 12 and actuator portion 14 .", "In FIG. 6 , wing nut 102 has been unscrewed to release stop tube 98 , placing plunger 60 in a maintenance position.", "In this position, stop tube 98 can be used to push mandrel 66 out of rear sleeve 76 , making it available for removal and replacement of seals 68 a - 68 c as required or any other maintenance which may be required.", "FIG. 2 illustrates plunger 60 of sampling apparatus is the “parked”", "position, a position placing mandrel head 66 a in a position to protect front sleeve 78 and mandrel head 66 a from damage caused by abrasive liquid flowing in vessel 1 .", "In this position, front piston 82 has been moved away from valve 11 to a position stopped by center head 90 .", "To reach this position, actuator air is applied to a piston-park port 108 causing front piston 82 to move away from valve 11 .", "Center head 90 provides a stopping position for front piston 82 which serves as a stop for rear piston 63 .", "FIG. 3 illustrates plunger 60 of sampling apparatus 10 in position to receive a liquid sample from within vessel 1 .", "Valve stem 24 is in position to align through-hole 26 h such that plunger 60 may pass through central valve portion 26 .", "In this sample-receiving position, the sample-receiving site formed within annular spacer 70 is open to capture liquid flowing through or being processed within vessel 1 .", "In this position, both front piston 82 and rear piston 63 are positioned as close to valve 11 as possible within their respective cylinders.", "To reach this position, actuator air is applied to a piston-apply port 104 causing pistons 63 and 82 to move toward valve 11 .", "From the sample-receiving position, the fixed volume of liquid in the sample-receiving space is then moved through adapter opening 18 and through front sleeve 78 into through-hole 26 h which forms the sample-delivery site.", "This sample-delivery position of sampling apparatus 10 is illustrated in FIG. 4 .", "In the sample-delivery position, rear piston 63 is moved within rear cylinder 86 until it reaches stop washer 99 on stop tube 98 .", "Stop washer 99 is positioned to place annular spacer 70 in the sample-delivery site within through-hole 26 h in central valve portion 26 .", "To reach this sample-delivery position, actuator air is applied to piston-retract port 106 to move rear piston 63 to its stop position created by stop washer 99 .", "In the sample-delivery position, bleed valve 20 can be used to effect transfer of the liquid sample contained in the sample-receiving space to a sample container (not shown) which may be connected to bleed valve 20 at bleed valve sample port 54 .", "FIG. 8 illustrates bleed valve 20 , a ball valve in this embodiment, in the closed position while sampling apparatus also in a closed position, indicating that sampling apparatus 10 is in a position ready for or undergoing maintenance as illustrated in FIGS. 5 and 6 , respectively.", "FIG. 9 illustrates bleed valve 20 in an open position with valve 11 also in an open position, thereby allowing a liquid sample to pass from the sample-delivery site in through-hole 26 h, through bleed valve 20 and into a sample container (not shown).", "Bleed valve 20 is attached to first stem portion 24 a such that when valve 11 is turned using valve handle 42 , the entire bleed valve 20 turns with stem 24 .", "FIG. 5 illustrates sampling apparatus in a maintenance position, ready for separation of actuator portion 14 from valve portion 12 as illustrated in FIG. 6 .", "To reach this position, wing nut 102 is removed from rear head 95 thereby allowing stop tube to move stop washer 99 away from valve 11 and thus allowing plunger 60 to be removed from valve 11 completely.", "With the stop washer 99 back against rear head 95 , actuator air applied to piston-retract port 106 causes rear piston to move farther back into rear cylinder 86 .", "A position called a “double-block-and-bleed”", "position is illustrated in FIG. 5 .", "With sampling apparatus in a position ready for maintenance, an operator is able to use external flush port 52 in combination with bleed valve 20 to ensure that valve 11 has been properly closed, thus isolating vessel 1 from sampling apparatus 10 , before sampling apparatus 10 is removed.", "In this position, it is also possible to ensure that the sample has been properly removed from the sample-delivery site in through-hole 26 h. This position of sampling apparatus 10 thus provides safety for the operator during operation of sampling apparatus 10 .", "The selection of materials to be used for the embodiment described herein follows sound engineering practice as known by those skilled in the state-of-the-art of process monitoring, chemical instrument design or mechanical design.", "In general, parts within the embodiment described herein may be made of stainless steel such as 316SS but are not limited to being made of stainless steel.", "Seal materials for O-rings can be but are not limited to commercially-available O-ring materials such as Viton® or nitrile, both known to those skilled in the art of mechanical design.", "Seals such as rear sleeve seals 76 a and 76 b may be made of PTFE (polytetrafluoroethylene) well known to those skilled in the art of mechanical design.", "Valve seats 28 a and 28 b may be made of TFM™, a modified PTFE material also well known to those skilled in the art of mechanical design.", "In some applications, front sleeve 78 may be required to withstand an highly-abrasive environment.", "In such cases, it may be useful to make front sleeve 78 from a material such as tungsten carbide.", "This and other materials are well-known to those skilled in the art of mechanical design.", "Front piston sleeve bearing 88 may be made of an appropriate sleeve bearing material such as silicon bronze or an oil- or PTFE-impregnated bearing material such as is well-known by those skilled in the art of mechanical design.", "Front piston 82 , front cylinder 84 , rear piston 63 , rear cylinder 86 , center head 90 , and rear head 95 all may be made out of aluminum.", "None of material suggested herein are meant to be limiting to the scope of the present invention.", "FIG. 10C illustrates an alternative embodiment for stem 24 and central valve portion 26 .", "In FIG. 10C , central valve portion 26 is a truncated cone;", "a large end 26 a of conical central valve portion 26 is adjacent to second stem portion 24 b and a small end 26 b of conical central valve portion 26 is adjacent to first stem portion 24 a. Referring to FIG. 3 , when, for example, front seal 68 a on mandrel head 66 of plunger 60 enters front sleeve 78 from vessel 1 , seal 68 a moves across a boundary between being unconstrained and being constrained (fitting tightly) within front sleeve 78 .", "Such a transition is called a seal/interface encounter.", "Each such encounter is an opportunity for any abrasive solid phase in the liquid from vessel 1 that is carried by the seal to cause wear of the seals.", "One significant advantage of placing the sample-delivery site within valve 11 is that there are fewer such encounters during a sample withdrawal cycle than with sampling apparatus of the prior art such as that described in U.S. Pat. No. 6,792,818 mentioned above.", "If the sample-receiving space was moved to a sample-delivery site on the side of valve opposite to vessel 1 as in Jaeger '818, several additional wear-causing encounters would occur, thereby reducing the life of the seals as compared to those in the present invention.", "Furthermore, through-hole 26 h is a clearance hole, i.e., larger in inside diameter compared to the outside diameters of front seal 68 a, middle seal 68 b, and rear seal 68 c on mandrel 66 such that these seals do not touch the walls of through-hole 26 h and such that any solid phase particles in the liquid being sample will not be pressed into these seals while sampling apparatus 10 is the sample-delivery position.", "In spite of the fact that first and second valve seats 28 a and 28 b ensure that stem 24 and central valve portion 26 remain in proper alignment within valve 11 , through-hole 26 h, being a clearance hole, also reduces the effect of any misalignment which may occur within valve 11 during the operation of sampling apparatus 10 .", "While the principles of this invention have been described in connection with specific embodiments, it should be understood clearly that these descriptions are made only by way of example and are not intended to limit the scope of the invention." ]
BACKGROUND OF THE INVENTION This invention relates to a control system which has a self-diagnostic function in which a sub-control circuit backs up a main control circuit when the main control circuit fails. The rapid progress of electronic technology has been accompanied by the employment of electronic control systems in many types of devices. For security purposes electronic control systems must be highly reliable and, therefore, employ sub-control circuits which operate as a queued redundant system. The sub-control circuit is designed so that it operates as a backup control system when a main control circuit fails. FIG. 1 illustrates an example of a control circuit and a sub-control circuit using microcomputers. In FIG. 1, a main microcomputer 1 receives data and outputs a control signal A 1 through an output port O a1 based on the data received. The control signal A 1 operates a driving transistor 2a which excites a coil 4 through a normally closed contact 3a of relay 3. The coil 4 can be used to drive or control controllable elements. The main microcomputer 1 samples a potential through an input port P a1 at a point between transistor 2a and contact 3a, and uses the potential as a diagnostic signal B 1 . When the logical relationship between the control signal A 1 and the diagnostic signal B 1 does not satisfy a predetermined condition, the main microcomputer 1 detects that the transistor 2a or coil 4 is abnormal and outputs a failure signal C 1 through an output port O a2 . The failure signal C 1 activates relay 3 to switch the contacts 3a and 3b, thus connecting the coil 4 to a transistor 2b of a sub-control system. When a sub-microcomputer 5 receives the failure signal C 1 through input port P b2 , the sub-microcomputer 5, which is in a standby state and receives the same input data as that applied to the main microcomputer 1, starts to control the excitation operation. The sub-microcomputer 5, based on the input data, outputs a control signal A 2 through output port O b1 to control the transistor 2b. The transistor 2b controls the coil 4 through the contact 3b. Thus, the sub-control system, including the sub-microcomputer 5 and the transistor 2b, backs up the main control system, including the main microcomputer 1 and transistor 2a. When the transistor 2b of the sub-control system fails, the sub-microcomputer 5, using the diagnostic signal B 2 input through input port P b1 , detects the non-coincidence of the control signal A 2 and the diagnostic signal B 2 . When the non-coincidence is detected the sub-microcomputer 5 outputs a failure signal C 2 through output port O b2 . When the failure signal C 2 is produced an alarm device 6 is activated and informs an operator that both the sub-control system and the main control system are out of order. Self-diagnosis takes place in the subcontrol system only after trouble occurs in the main control system. Therefore, the above-described self diagnostic method is only effective when the main control system fails and the sub-control system is activated as a backup. Thus, when the transistor 2b fails before the backup operation is initiated the sub-control circuit is out of order before the backup operation is required. In this situation the failure signal C 2 is produced immediately, the alarm device 6 is activated and the sub-control system provides no backup function for the main control system. The above-described queued redundant system operates on the premise that the sub-control system functions normally at all times. The above-described sub-control system cannot be employed for electronic devices on vehicles which must be very high in reliability. SUMMARY OF THE INVENTION An object of this invention is to provide a control system with a self-diagnostic function. Another object of this invention is to provide a control system which has a self diagnostic function for both a main control system and a sub-control system. An additional object of this invention is to provide a sub-control system with a self disgnostic function which operates in a standby state. It is a further object of this invention to provide a control system with high reliability. It is another object of this invention to provide a secure and reliable vehicle control system. The present invention provides a control system which includes a reset signal generating circuit. The reset signal generating circuit controls a reset control operation in the sub-control svstem while the sub-control system is in a self-diagnostic mode. The sub-control system includes a sub-microcomputer which is finally released from a reset state after both a main microcomputer of a main control system and the sub-microcomputer are reset. The main control system also includes a self-diagnostic mode which initiates a backup operation by the sub-control system when the main control system malfunctions. The control system also includes an alarm circuit for detecting a failure signal generated by the sub-microcomputer while it is in the self diagnostic mode. These together with other objects and advantages which will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram illustrating an example of a control system having a sub-control system; FIG. 2 is a circuit diagram an embodiment of a self diagnostic device of a sub-control system according to the present invention; FIG. 3 is a circuit diagram of an example of the reset signal generating circuit 29 illustrated in FIG. 2; FIG. 4 is a circuit diagram of an example of the alarm circuit 34 illustrated in FIG. 2; FIGS. 5-10 are wave form diagrams of the signals in the circuits illustrated in FIG. 2; and FIG. 11 is a flow chart illustrating a self diagnostic process of the sub-control system. DESCRIPTION OF THE PREFERRED EMBODIMENT A control system having a self-diagnostic function according to the present invention will be described with reference to FIGS. 2-11. FIG. 2 illustrates an example of a control system with self-diagnostic functions, according to the present invention, applicable in a situation where a sub-control system backs up two main control systems. A first main microcomputer 10 outputs a control signal A 1 through an output port O a1 which operates a driver 11. The driver 11 is connected to a +V power source and to an exciting coil 13 through a contact 12a of a relay 12. The driver 11 drives the exciting coil 13 of an element to be controlled. The first main microcomputer 10 samples a diagnositic signal B 1 through an input port P a1 at a point between the driver 11 and the relay contact 12a. The microcomputer 10 compares the diagnostic signal B 1 with the control signal A 1 to detect a predetermined logical non-coincidence which indicates that either the exciting coil 13 or a transistor in the driver 11 is malfunctioning. When the abnormality is detected the first main microcomputer 10 generates a failure signal C 1 which activates the relay 12. The failure signal C 1 breaks and makes the contacts 12a and 12b, respectively, in the relay 12, thus connecting the exciting coil 13 to a driver 14. As in the case of the first main microcomputer 10, a second main microcomputer 15, which is part of a second main control system, outputs a control signal A 3 through an output port O c1 to control a driver 16. The driver 16 connects a +V power source through a normally closed contact 17a of the relay 17 to an exciting coil 18 The exciting coil 18 is part of an element that is to be driven and controlled. The second main microcomputer 15 samples a diagnostic signal B 3 through an input port O c1 at a point between the driver 16 and the exciting coil 18. The diagnostic signal B 3 is used to detect whether either the exciting coil 18 or a transistor in the driver 16 is malfunctioning. A failure signal C 3 output through an output port O c2 drives the relay 17 which breaks and makes the contacts 17a and 17b, respectively, so that the exciting coil 18 is connected to a driver 19. The sub-microcomputer 20, which is a part of a queued redundant sub-control system, outputs the control signal A 2 through an output port O b1 when it receives the failure signal C 1 from the first main microcomputer 10 or the failure signal C 3 from the second main microcomputer 15. A signal control means including an OR gate 21 also receives the failure signal C 1 and the failure signal C 3 after it passes through an inverter 22. An AND gate 23 of the signal control means receives the control signal A 2 and the output from the OR gate 21 and operates the driver 14. An AND gate 24 of the signal control means receives the control signal A 2 and the output from the OR gate 21 after it passes through an inverter 25, and operates the driver 19. The sub-microcomputer 20 receives, as a diagnostic signal B 2a , a potential sampled at a point between the driver 14 and the contact 12b. The sub-microcomputer 20 also receives, as a diagnostic signal B 2b , a potential sampled at a point between the driver 19 and the contact 17b. The sub-microcomputer 20 receives the diagnostic signals B 2a and B 2b through input ports P b1 and P b2 , respectively. When the sub-microcomputer 20 detects the failure signals C 1 or C 3 and the predetermined non-coincidence logical relationship of the diagnostic signals B 2a or B 2b with respect to the control signal A 2 , the sub-microcomputer 20 generates a failure signal C 2 . An initial signal generating circuit 26 generates an initial signal IS when power is turned on in the initial signal generating circuit 26. The initial signal generatinq circuit 26 is a series circuit of a capacitor 27 and a resistor 28. When the initial signal IS is received by a reset signal generating circuit 29, the reset signal generating circuit 29 outputs reset signals RS 1 , RS 2 and RS 3 . The reset signals RS 1 , RS 2 and RS 3 are supplied to the sub-microcomputer 20, the first main microcomputer 10 and the second main microcomputer 15 during a predetermined queued redundant system diagnostic mode. As illustrated in FIG. 3, the reset signal generating circuit 29 includes four D-type flip-flop circuits 30a-30d of which a set output Q of a previous flip-flop is connected to a D input of a succeeding flip-flop. The flip-flop circuits 30a-30d are reset by the initial signal IS. The reset signal generating circuit 29 also includes an OR gate 31 which receives clock pulses CP and an output produced by the set output Q of the flip-flop 30d. The reset signal generating circuit 29 further includes an inverter 32 connected between OR gate 31 and the clock inputs CLK of the the flip-flop circuits 30a-30d. The reset signal generating circuit 29 additionally includes an AND gate 33 connected to the output of the OR gate 31 and the set output Q of the flip-flop 30a. The AND gate 33 generates the reset signal RS 1 . The reset signals RS 2 and RS 3 are output from the set outputs Q of the flip-flop circuits 30b and 30c, respectively. Alarm circuit 34, illustrated in FIG. 2, receives the failure signal C 2 output by the sub-microcomputer 20 and the reset signals RS 2 and RS 3 output by the reset signal generating circuit 29. The alarm circuit 34 detects an abnormal condition or malfunction in the sub-control system, which is the queued redundant system, and outputs an alarm signal AL. The alarm circuit 34, as illustrated in FIG. 4, includes a delay circuit 37 of an integrator type, which includes a resistor 35 and a capacitor 36, for delaying the failure signal C 2 . A flip-flop circuit 38 receives the delayed failure signal C 2 output by the delay circuit 37 through a D input terminal and the reset signal RS 2 through a clock input terminal CLK. The alarm circuit 34 also includes flip-flop circuit 39 which also receives the delayed failure signal C 2 through a D input terminal and the reset signal RS 3 through a clock input terminal CLK. An OR gate 40, included in the alarm circuit 34, receives the set outputs Q from the flip-flops 38 and 39 and outputs the alarm signal AL. In the above-described circuits, when a power switch (not shown) is turned on, the +V power source is applied to the initial signal generating circuit 26 and generates the initial signal IS as illustrated in FIG. 5(a). After the reset signal generating circuit 29 is activated by the initial signal IS, the reset signals RS 1 , RS 2 and RS 3 are generated. When the sub-microcomputer 20, the first main microcomputer 10 and the second main microcomputer 15, which are in a predetermined mode, receive the reset signals, the self-diagnostic mode of the sub-microcomputer 20, comprising the queued redundant system, is established. The operation of the reset signal generating circuit 29 will be described before describing the operation of the queued redundant system in the self-diagnostic mode. When the initial signal IS is supplied to the reset signal generating circuit 29, illustrated in FIG. 3, the flip-flop circuits 30a-30d are reset. When the +V power source is activated in the initial signal generating circuit 26, a clock pulse oscillator (not shown) is also turned on, so that a clock pulse CP (illustrated in FIG. 5(b)) is applied to one of the input terminals of the OR gate 31. The clock pulse CP which passes through the OR gate 31 is inverted by the inverter 32, as illustrated in FIG. 5(c). The clock pulse CP after inversion is input through the clock input terminal CLK of the flip-flop circuit 30a. Because the input terminal of the flip-flip 30a is connected to the +V power source, the flip-flop 30a is set by the rising edge of the clock pulse CP and the output produced by the set output Q rises, as illustrated in FIG. 5(d). The output produced from the set output Q of the flip-flip 30a is applied to the D input terminal of the flip-flop circuit 30b. Therefore, if the D input of the flip-flop 30b is at a high level, then at the next rising edge of the clock pulse CP, as illustrated in FIG. 5(c), the set output of the flip-flop 30b rises, as illustrated in FIG. 5(b). In a similar manner, the output produced by the Q output of the flip-flip 30c rises at the leading edge of the third clock pulse CP, as illustrated in FIG. 5(f). The set output Q of the flip-flop 30c is connected to the D input terminal of flip-flop circuit 30d. Therefore, the flip-flop 30d is set at the rising edge of the fourth clock pulse CP, as illustrated in FIGS. 5(b) and 5(g). The set output Q of the flip-flop circuit 30d is connected to the other input terminal of the OR gate 31 which results in the output of the OR gate 31 being maintained at the high level while the output produced by the inverter 32 is maintained at the low level. Accordingly, the set outputs Q of the flip-flop circuits 30a-30d are maintained at the high level. The AND gate 33 receives the output produced by the OR gate 31 and that produced by the set output Q of the flip-flop circuit 30a. During the time between the instant when the flip-flop circuit 30a is set until the flip-flop circuit 30d is set, the AND gate 33 produces a pulse output, as illustrated in FIG. 5(h), which is synchronized with the output of the OR gate 31. When the flip-flop circuit 30d is set the output produced by AND gate 33 is held at the high level. The output produced by the AND gate 33 is used as the reset signal RS 1 , the output produced by the set output Q of the flip-flop circuit 30b is used as the reset signal RS 2 and the output produced by the set output Q of the flip-flop 30c is used as the reset signal RS 3 . As illustrated in FIGS. 5(h), 5(e) and 5(f) the reset signals RS 1 -RS 3 change during first through fourth modes as illustrated in Table 1 below whenever the clock pulse CP occurs, and the levels of the reset signals are held at the levels obtained in the fourth mode thereafter. TABLE 1______________________________________MODE RS.sub.1 RS.sub.2 RS.sub.3______________________________________1 L L L2 H L L3 H H L4 H H H______________________________________ Where H equals the high level and L equals the low level. As illustrated in Table 1 above, when the initial signal IS is supplied to the reset signal generating circuit 29, illustrated in FIG. 3, the reset signals RS 1 -RS 3 are set to the low level, so that the sub-microcomputer 20 and the first and second main microcomputers 10 and 15 are reset. Thereafter, the reset states of the microcomputers are released sequentially, beginning with the sub-microcomputer 20 which forms the queued redundant system, each time a clock pulse CP is applied. The sub-microcomputer is temporarily reset at the beginning of the third and fourth modes, as illustrated in FIG. 6. The self-diagnostic operation of the queued redundant system beginning at the application of power will be described. When the +V power source is turned on at the time t 1 , as illustrated in FIG. 6(a), the reset signals RS 1 -RS 3 are at the levels illustrated in FIG. 6(b), 6(c) and 6(d). In the first mode, during the period t 1 -t 2 , the reset signals RS 1 -RS 3 are at the low level, as illustrated in Table 1, and the sub-microcomputer 20 and the first and second microcomputers 10 and 15 are reset. While these microcomputers 20, 10 and 15 are reset the failure signals C 2 , C 1 and C 3 are at the high level, as illustrated in FIG. 6(e), 6(f) and 6(g), which indicates the detection of a malfunction. At the time instant t 2 , the reset signal RS 1 is raised to the high level, as illustrated in FIG. 6(b), and the reset state of the sub-microcomputer 20 is released. In the second mode, during the period t 2 -t 3 , while the sub-microcomputer 20 is not in the reset state, the sub-microcomputer 20 receives the failure signals C 1 and C 3 from the first and second main microcomputers 10 and 15 and generates the control signal A 2 , thereby causing the backup operation to occur. If, as in this case, the failure signals C 1 and C 3 are produced at the same time, the failure signal C 1 takes precedence, because the failure C 3 is inverted by the inverter 22. The output of the AND gate 23 is raised to the high level and the driver 14 is operated. Since the failure signal C 1 also operates the relay 12, the contacts 12a and 12b are switched and the exciting coil 13 is driven by the output of the driver 14, rather than being driven by the first main microcomputer 10. The potential between the driver 14 and the contact 12b is sampled as the diagnostic signal B 2a by the sub-microcomputer 20. Sub-microcomputer 20 diagnoses the condition of the driver 14 and the exciting coil 13 with respect to the control signal A 2 . When the diagnostic result indicates that the driver 14 or the exciting coil 13 is normal, the failure C 2 is set to the low level as indicated in the period t 3 -t 4 in FIG. 6(g). If an abnormal condition is detected, such as a breakage of the coil 13 or a bad driver 14, a failure signal C 2 is set to the low level momentarily as indicated in the period t 3 -t 4 in FIG. 6(h), and is then held at the high level. In the third mode, at the time t 4 , as illustrated in FIGS. 6(b) and 6(c), the reset signal RS 1 is set to the low level resetting the sub-microcomputer 20, while the reset signal RS 2 is raised to the high level. Therefore, the reset state of the first microcomputer 10 is released and the reset state of the second main microcomputer 15 is maintained. During the period t 4 -t 5 a diagnosis of the driver 11 and the exciting coil 13 is performed. When the diagnostic result indicates that the driver 11 and the exciting coil 13 are both normal, the failure signal C 1 is set to the low level at the time t 5 , as illustrated in FIG. 6(e). At the time t 6 , the reset signal RS 1 is set to the high level and only the second main microcomputer 15 is in the reset state. Accordingly, at the time t 6 only the failure signal C 3 is at the high level, as illustrated in FIG. 6(f), and the sub-microcomputer 20 starts the backup operation for the second main microcomputer 15 by generating the control signal A 2 . The failure signal C 3 is at the high level and therefore the output of the inverter 22, at the low level, is supplied through the OR gate 21 to the AND gate 24 via the inverter 25. Thus, the control signal A 2 drives the driver 19 through the AND gate 24. The contacts 17a and 17b of the relay 17 are also operated by the failure C 3 , so that the exciting coil 18 is driven by the output of the driver 19. The sub-microcomputer 20 samples, as the diagnostic signal B 2b , the potential at a point between the driver 19 and the contact 17b. If the diagnostic signal B 2b indicates a normal operation with respect to the control signal A 2 , the sub-microcomputer 20 generates a low level signal as the failure signal C 2 during the period t 7 -t 8 , as illustrated in FIG. 6(g). If the diagnostic signal B 2b indicates an abnormal operation, the sub-microcomputer 20 provides the failure signal C 2 at the high level, which set to the low level momentarily during the period t 7 -t 8 , as illustrated in FIG. 6(i). In the fourth mode, at the time t 8 , the reset RS 1 is set to the low level temporarily while the reset RS 3 is raised to the high level, and therefore, only the sub-microcomputer 20 is reset. The second main microcomputer 15 carries out the self diagnostic operation during the period t 8 -t 9 . If the self diagnostic signal indicates a normal operation, the failure signal C 3 is set to the low level at the time t 9 , as illustrated in FIG. 6(f). At the time t 10 the reset signal RS 1 is raised to the high level as illustrated in FIG. 6(b), and the reset state of the sub-microcomputer 20 is released. Thus, all the self-diagnostic operations of the queued redundant systems have been accomplished and all the microcomputers are in a normal operating state. In the self-diagnosis mode, operating currents are supplied to the exciting coils 13 and 18. However, since the self-diagnosis is achieved in a very short time, the elements to be controlled by the exciting coils 13 and 18 are not driven by the operating currents, that is, no adverse affects are caused by the operating currents flowing during the self-diagnosis mode. Thus, the failure signal C 2 which represents the condition of the sub-control system is applied to alarm circuit 34. The alarm circuit 34 detects the wave forms during the periods t 3 -t 4 , as illustrated in FIG. 6(h), or during the time period t 7 -t 8 , as illustrated in FIG. 6(i), to produce the alarm signal AL. An alarm circuit 34 discrimination operation will be described with reference to FIG. 4 and FIGS. 7-10. When the initial signal IS generated by the initial signal generating circuit 26 (FIG. 2) is supplied to the flip-flops 38 and 39, illustrated in FIG. 4, they are reset. The failure signal C 2 output bv the sub-microcomputer 20 through the output port O b2 (FIG. 2), and is applied to the D input terminals of the flip-flop circuits 38 and 39 (FIG. 4) after being delayed by the delay circuit 37 for a time period ΔT. The reset signals RS 2 and RS 3 are applied to the clock input terminals CLK of the flip-flop circuits 38 and 39, respectively. The flip-flop circuits 38 and 39 carry out the discrimination operation based on the presence or absence of the failure signal C 2 which is supplied through the delay circuit 37 during the period that the high level reset signals RS 2 and RS 3 are supplied. When the failure signal C 2 , during a normal period, is supplied to the flip-flop circuits 38 and 39 after being delayed by the delay circuit 37 for the time ΔT, as illustrated in FIG. 7(a), the input signal applied to the D terminal of the flip-flop circuit 38 is at the low level, i.e., being delayed as illustrated in FIG. 7(a), at the time t 4 when the reset signal RS 2 rises, as illustrated in FIG. 7(b). Accordingly, the flip-flop circuit 38 is not set and the set output Q is maintained at the low level. Therefore, no high level alarm signal AL is output by OR gate 40, as illustrated in FIG. 7(c). When a failure signal C 2 , as illustrated in FIG. 6(h), indicating the abnormal condition of the driver 14 or the exciting coil 13 during the period t 2 -t 7 , is supplied to the D input terminals of the flip-flop circuits 38 and 39 via the delay circuit 37, as i11ustrated in FIG. 8(a), the flip-flop circuit 38 is reset at the time t 4 when the reset signal RS 2 rises. Thus, the set output Q of the flip-flop circuit 38 outputs through the OR gate 40 the high level of the alarm signal AL signalling that the queued redundant system is abnormal, as illustrated in FIG. 8(c). When the failure signal C 2 , indicating the normal operation of the driver 19 and the exciting coil 18, is supplied to the alarm circuit, the low level of the failure signal C 2 is delayed at the time t 8 , as illustrated in FIG. 9(a). The failure signal C 2 is at a low level when the reset signal RS 3 rises and is raised to the high level, as illustrated in FIG. 9(b). Therefore, the flip-flop circuit 39 is not set and the output produced by the OR gate 40 is maintained at the low level, as illustrated in FIG. 9(c). When the driver 19 and the exciting coil 18 are malfunctioning the failure signal C 2 is supplied through the delay circuit 37, as illustrated in FIG. 10(a). The failure signal C 2 is at the high level at the time t 8 when the reset signal RS 3 rises and is raised to the high level, and therefore, the flip-flop circuit 39 is set as illustrated in FIG. 10(b). As a result, the OR gate 40 which receives the output produced by the set output Q of the flip-flop circuit 39 outputs the high level of the alarm signal AL, as illustrated in FIG. 10(c), signalling that the queued redundant system is abnormal. FIG. 11 is a flow chart illustrating the self-diagnostic operation of the queued redundant system. Block 1 indicates that when the power is applied, one of the failure signals generated by the main control systems is set to the low level. Block 2 indicates that the sub-control system produces a control signal causing the backup operation for one of the main control systems to begin. Block 3 indicates that the sub-control system performs the self-diagnostic operation and block 4 is a branch box in which the branch selected depends upon the diagnostic result. Block 5 indicates that the sub-control system for the backup operation for the main microcomputer system is performing normally and the failure signal is set to the high level. The backup operation for the first or second main microcomputer 10 or 15 by the sub-microcomputer 20 will be described. When the driver 11 fails, i.e., becomes abnormal, the first main microcomputer 10 detects the abnormal condition of the diagnostic signal B 1 with respect to a control signal A 1 and outputs a failure signal C 1 . When failure signal C 1 is output, the relay 12 is activated, and the exciting coil 13 is connected to the driver 14 in the sub-control system. Furthermore, on the production of the failure signal C 1 , the sub-microcomputer 20 produces the control signal A 2 . Since the output of the OR gate 21 has been raised to the high level by the failure signal C 1 the control signal A 2 is passed through the AND gate 23 to the driver 14. Thus, the driver 14 is operated by the control signal A 2 and the exciting coil 13 is driven by the output of the driver 14 and the backup operation is accomplished. This backup operation is similarly performed for the second main microcomputer 15. When the first and second main microcomputers 10 and 15 provide the failure signals C 1 and C 2 at the same time, the first main microcomputer 10 takes precedence in the backup operation over the second main microcomputer 15 because of the signal control means including the OR gate 21, the inverters 22 and 25, and the AND gates 23 and 24. In the above described embodiment, there is only one queued redundant system, i.e. one sub-microcomputer 20, which backs up two main control systems. However, it should be noted that the number of main control systems can be selected as desired. As is apparent in the above description, in the control system according to the present invention, when the power is turned on, the main control systems and the sub-control system are reset. Then the reset state of the sub-control system is released so that a failure signal is produced by one of the main control systems in order to momentarily cause a backup operation. During this backup operation, self-diagnostics are performed by the sub-control system under predetermined conditions. Thus, whenever the power source is turned on, the self-diagnostic functions of the sub-control system are effected. As can be seen from the above description, the present control system having the self-diagnostic function is simple in arrangement and high in reliability. The many features and advantaqes of the invention are apparent from the detailed specification and thus it is intended by the appended claims to cover all such features and advantages of the system which fall within the true spirit and scope of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
The present invention includes a main control system driving an exciting coil of a component to be driven. The invention also includes a sub-control system that backs up the main control system when the main control system fails. The sub-control system and the main control system both have a self-diagnostic capability and the sub-control system is diagnosed for failure prior to the main control system, so that the availability of the back up system is determined before the main control system is activated.
Briefly summarize the main idea's components and working principles as described in the context.
[ "BACKGROUND OF THE INVENTION This invention relates to a control system which has a self-diagnostic function in which a sub-control circuit backs up a main control circuit when the main control circuit fails.", "The rapid progress of electronic technology has been accompanied by the employment of electronic control systems in many types of devices.", "For security purposes electronic control systems must be highly reliable and, therefore, employ sub-control circuits which operate as a queued redundant system.", "The sub-control circuit is designed so that it operates as a backup control system when a main control circuit fails.", "FIG. 1 illustrates an example of a control circuit and a sub-control circuit using microcomputers.", "In FIG. 1, a main microcomputer 1 receives data and outputs a control signal A 1 through an output port O a1 based on the data received.", "The control signal A 1 operates a driving transistor 2a which excites a coil 4 through a normally closed contact 3a of relay 3.", "The coil 4 can be used to drive or control controllable elements.", "The main microcomputer 1 samples a potential through an input port P a1 at a point between transistor 2a and contact 3a, and uses the potential as a diagnostic signal B 1 .", "When the logical relationship between the control signal A 1 and the diagnostic signal B 1 does not satisfy a predetermined condition, the main microcomputer 1 detects that the transistor 2a or coil 4 is abnormal and outputs a failure signal C 1 through an output port O a2 .", "The failure signal C 1 activates relay 3 to switch the contacts 3a and 3b, thus connecting the coil 4 to a transistor 2b of a sub-control system.", "When a sub-microcomputer 5 receives the failure signal C 1 through input port P b2 , the sub-microcomputer 5, which is in a standby state and receives the same input data as that applied to the main microcomputer 1, starts to control the excitation operation.", "The sub-microcomputer 5, based on the input data, outputs a control signal A 2 through output port O b1 to control the transistor 2b.", "The transistor 2b controls the coil 4 through the contact 3b.", "Thus, the sub-control system, including the sub-microcomputer 5 and the transistor 2b, backs up the main control system, including the main microcomputer 1 and transistor 2a.", "When the transistor 2b of the sub-control system fails, the sub-microcomputer 5, using the diagnostic signal B 2 input through input port P b1 , detects the non-coincidence of the control signal A 2 and the diagnostic signal B 2 .", "When the non-coincidence is detected the sub-microcomputer 5 outputs a failure signal C 2 through output port O b2 .", "When the failure signal C 2 is produced an alarm device 6 is activated and informs an operator that both the sub-control system and the main control system are out of order.", "Self-diagnosis takes place in the subcontrol system only after trouble occurs in the main control system.", "Therefore, the above-described self diagnostic method is only effective when the main control system fails and the sub-control system is activated as a backup.", "Thus, when the transistor 2b fails before the backup operation is initiated the sub-control circuit is out of order before the backup operation is required.", "In this situation the failure signal C 2 is produced immediately, the alarm device 6 is activated and the sub-control system provides no backup function for the main control system.", "The above-described queued redundant system operates on the premise that the sub-control system functions normally at all times.", "The above-described sub-control system cannot be employed for electronic devices on vehicles which must be very high in reliability.", "SUMMARY OF THE INVENTION An object of this invention is to provide a control system with a self-diagnostic function.", "Another object of this invention is to provide a control system which has a self diagnostic function for both a main control system and a sub-control system.", "An additional object of this invention is to provide a sub-control system with a self disgnostic function which operates in a standby state.", "It is a further object of this invention to provide a control system with high reliability.", "It is another object of this invention to provide a secure and reliable vehicle control system.", "The present invention provides a control system which includes a reset signal generating circuit.", "The reset signal generating circuit controls a reset control operation in the sub-control svstem while the sub-control system is in a self-diagnostic mode.", "The sub-control system includes a sub-microcomputer which is finally released from a reset state after both a main microcomputer of a main control system and the sub-microcomputer are reset.", "The main control system also includes a self-diagnostic mode which initiates a backup operation by the sub-control system when the main control system malfunctions.", "The control system also includes an alarm circuit for detecting a failure signal generated by the sub-microcomputer while it is in the self diagnostic mode.", "These together with other objects and advantages which will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram illustrating an example of a control system having a sub-control system;", "FIG. 2 is a circuit diagram an embodiment of a self diagnostic device of a sub-control system according to the present invention;", "FIG. 3 is a circuit diagram of an example of the reset signal generating circuit 29 illustrated in FIG. 2;", "FIG. 4 is a circuit diagram of an example of the alarm circuit 34 illustrated in FIG. 2;", "FIGS. 5-10 are wave form diagrams of the signals in the circuits illustrated in FIG. 2;", "and FIG. 11 is a flow chart illustrating a self diagnostic process of the sub-control system.", "DESCRIPTION OF THE PREFERRED EMBODIMENT A control system having a self-diagnostic function according to the present invention will be described with reference to FIGS. 2-11.", "FIG. 2 illustrates an example of a control system with self-diagnostic functions, according to the present invention, applicable in a situation where a sub-control system backs up two main control systems.", "A first main microcomputer 10 outputs a control signal A 1 through an output port O a1 which operates a driver 11.", "The driver 11 is connected to a +V power source and to an exciting coil 13 through a contact 12a of a relay 12.", "The driver 11 drives the exciting coil 13 of an element to be controlled.", "The first main microcomputer 10 samples a diagnositic signal B 1 through an input port P a1 at a point between the driver 11 and the relay contact 12a.", "The microcomputer 10 compares the diagnostic signal B 1 with the control signal A 1 to detect a predetermined logical non-coincidence which indicates that either the exciting coil 13 or a transistor in the driver 11 is malfunctioning.", "When the abnormality is detected the first main microcomputer 10 generates a failure signal C 1 which activates the relay 12.", "The failure signal C 1 breaks and makes the contacts 12a and 12b, respectively, in the relay 12, thus connecting the exciting coil 13 to a driver 14.", "As in the case of the first main microcomputer 10, a second main microcomputer 15, which is part of a second main control system, outputs a control signal A 3 through an output port O c1 to control a driver 16.", "The driver 16 connects a +V power source through a normally closed contact 17a of the relay 17 to an exciting coil 18 The exciting coil 18 is part of an element that is to be driven and controlled.", "The second main microcomputer 15 samples a diagnostic signal B 3 through an input port O c1 at a point between the driver 16 and the exciting coil 18.", "The diagnostic signal B 3 is used to detect whether either the exciting coil 18 or a transistor in the driver 16 is malfunctioning.", "A failure signal C 3 output through an output port O c2 drives the relay 17 which breaks and makes the contacts 17a and 17b, respectively, so that the exciting coil 18 is connected to a driver 19.", "The sub-microcomputer 20, which is a part of a queued redundant sub-control system, outputs the control signal A 2 through an output port O b1 when it receives the failure signal C 1 from the first main microcomputer 10 or the failure signal C 3 from the second main microcomputer 15.", "A signal control means including an OR gate 21 also receives the failure signal C 1 and the failure signal C 3 after it passes through an inverter 22.", "An AND gate 23 of the signal control means receives the control signal A 2 and the output from the OR gate 21 and operates the driver 14.", "An AND gate 24 of the signal control means receives the control signal A 2 and the output from the OR gate 21 after it passes through an inverter 25, and operates the driver 19.", "The sub-microcomputer 20 receives, as a diagnostic signal B 2a , a potential sampled at a point between the driver 14 and the contact 12b.", "The sub-microcomputer 20 also receives, as a diagnostic signal B 2b , a potential sampled at a point between the driver 19 and the contact 17b.", "The sub-microcomputer 20 receives the diagnostic signals B 2a and B 2b through input ports P b1 and P b2 , respectively.", "When the sub-microcomputer 20 detects the failure signals C 1 or C 3 and the predetermined non-coincidence logical relationship of the diagnostic signals B 2a or B 2b with respect to the control signal A 2 , the sub-microcomputer 20 generates a failure signal C 2 .", "An initial signal generating circuit 26 generates an initial signal IS when power is turned on in the initial signal generating circuit 26.", "The initial signal generatinq circuit 26 is a series circuit of a capacitor 27 and a resistor 28.", "When the initial signal IS is received by a reset signal generating circuit 29, the reset signal generating circuit 29 outputs reset signals RS 1 , RS 2 and RS 3 .", "The reset signals RS 1 , RS 2 and RS 3 are supplied to the sub-microcomputer 20, the first main microcomputer 10 and the second main microcomputer 15 during a predetermined queued redundant system diagnostic mode.", "As illustrated in FIG. 3, the reset signal generating circuit 29 includes four D-type flip-flop circuits 30a-30d of which a set output Q of a previous flip-flop is connected to a D input of a succeeding flip-flop.", "The flip-flop circuits 30a-30d are reset by the initial signal IS.", "The reset signal generating circuit 29 also includes an OR gate 31 which receives clock pulses CP and an output produced by the set output Q of the flip-flop 30d.", "The reset signal generating circuit 29 further includes an inverter 32 connected between OR gate 31 and the clock inputs CLK of the the flip-flop circuits 30a-30d.", "The reset signal generating circuit 29 additionally includes an AND gate 33 connected to the output of the OR gate 31 and the set output Q of the flip-flop 30a.", "The AND gate 33 generates the reset signal RS 1 .", "The reset signals RS 2 and RS 3 are output from the set outputs Q of the flip-flop circuits 30b and 30c, respectively.", "Alarm circuit 34, illustrated in FIG. 2, receives the failure signal C 2 output by the sub-microcomputer 20 and the reset signals RS 2 and RS 3 output by the reset signal generating circuit 29.", "The alarm circuit 34 detects an abnormal condition or malfunction in the sub-control system, which is the queued redundant system, and outputs an alarm signal AL.", "The alarm circuit 34, as illustrated in FIG. 4, includes a delay circuit 37 of an integrator type, which includes a resistor 35 and a capacitor 36, for delaying the failure signal C 2 .", "A flip-flop circuit 38 receives the delayed failure signal C 2 output by the delay circuit 37 through a D input terminal and the reset signal RS 2 through a clock input terminal CLK.", "The alarm circuit 34 also includes flip-flop circuit 39 which also receives the delayed failure signal C 2 through a D input terminal and the reset signal RS 3 through a clock input terminal CLK.", "An OR gate 40, included in the alarm circuit 34, receives the set outputs Q from the flip-flops 38 and 39 and outputs the alarm signal AL.", "In the above-described circuits, when a power switch (not shown) is turned on, the +V power source is applied to the initial signal generating circuit 26 and generates the initial signal IS as illustrated in FIG. 5(a).", "After the reset signal generating circuit 29 is activated by the initial signal IS, the reset signals RS 1 , RS 2 and RS 3 are generated.", "When the sub-microcomputer 20, the first main microcomputer 10 and the second main microcomputer 15, which are in a predetermined mode, receive the reset signals, the self-diagnostic mode of the sub-microcomputer 20, comprising the queued redundant system, is established.", "The operation of the reset signal generating circuit 29 will be described before describing the operation of the queued redundant system in the self-diagnostic mode.", "When the initial signal IS is supplied to the reset signal generating circuit 29, illustrated in FIG. 3, the flip-flop circuits 30a-30d are reset.", "When the +V power source is activated in the initial signal generating circuit 26, a clock pulse oscillator (not shown) is also turned on, so that a clock pulse CP (illustrated in FIG. 5(b)) is applied to one of the input terminals of the OR gate 31.", "The clock pulse CP which passes through the OR gate 31 is inverted by the inverter 32, as illustrated in FIG. 5(c).", "The clock pulse CP after inversion is input through the clock input terminal CLK of the flip-flop circuit 30a.", "Because the input terminal of the flip-flip 30a is connected to the +V power source, the flip-flop 30a is set by the rising edge of the clock pulse CP and the output produced by the set output Q rises, as illustrated in FIG. 5(d).", "The output produced from the set output Q of the flip-flip 30a is applied to the D input terminal of the flip-flop circuit 30b.", "Therefore, if the D input of the flip-flop 30b is at a high level, then at the next rising edge of the clock pulse CP, as illustrated in FIG. 5(c), the set output of the flip-flop 30b rises, as illustrated in FIG. 5(b).", "In a similar manner, the output produced by the Q output of the flip-flip 30c rises at the leading edge of the third clock pulse CP, as illustrated in FIG. 5(f).", "The set output Q of the flip-flop 30c is connected to the D input terminal of flip-flop circuit 30d.", "Therefore, the flip-flop 30d is set at the rising edge of the fourth clock pulse CP, as illustrated in FIGS. 5(b) and 5(g).", "The set output Q of the flip-flop circuit 30d is connected to the other input terminal of the OR gate 31 which results in the output of the OR gate 31 being maintained at the high level while the output produced by the inverter 32 is maintained at the low level.", "Accordingly, the set outputs Q of the flip-flop circuits 30a-30d are maintained at the high level.", "The AND gate 33 receives the output produced by the OR gate 31 and that produced by the set output Q of the flip-flop circuit 30a.", "During the time between the instant when the flip-flop circuit 30a is set until the flip-flop circuit 30d is set, the AND gate 33 produces a pulse output, as illustrated in FIG. 5(h), which is synchronized with the output of the OR gate 31.", "When the flip-flop circuit 30d is set the output produced by AND gate 33 is held at the high level.", "The output produced by the AND gate 33 is used as the reset signal RS 1 , the output produced by the set output Q of the flip-flop circuit 30b is used as the reset signal RS 2 and the output produced by the set output Q of the flip-flop 30c is used as the reset signal RS 3 .", "As illustrated in FIGS. 5(h), 5(e) and 5(f) the reset signals RS 1 -RS 3 change during first through fourth modes as illustrated in Table 1 below whenever the clock pulse CP occurs, and the levels of the reset signals are held at the levels obtained in the fourth mode thereafter.", "TABLE 1______________________________________MODE RS.", "sub[.", "].1 RS.", "sub[.", "].2 RS.", "sub[.", "].3______________________________________1 L L L2 H L L3 H H L4 H H H______________________________________ Where H equals the high level and L equals the low level.", "As illustrated in Table 1 above, when the initial signal IS is supplied to the reset signal generating circuit 29, illustrated in FIG. 3, the reset signals RS 1 -RS 3 are set to the low level, so that the sub-microcomputer 20 and the first and second main microcomputers 10 and 15 are reset.", "Thereafter, the reset states of the microcomputers are released sequentially, beginning with the sub-microcomputer 20 which forms the queued redundant system, each time a clock pulse CP is applied.", "The sub-microcomputer is temporarily reset at the beginning of the third and fourth modes, as illustrated in FIG. 6. The self-diagnostic operation of the queued redundant system beginning at the application of power will be described.", "When the +V power source is turned on at the time t 1 , as illustrated in FIG. 6(a), the reset signals RS 1 -RS 3 are at the levels illustrated in FIG. 6(b), 6(c) and 6(d).", "In the first mode, during the period t 1 -t 2 , the reset signals RS 1 -RS 3 are at the low level, as illustrated in Table 1, and the sub-microcomputer 20 and the first and second microcomputers 10 and 15 are reset.", "While these microcomputers 20, 10 and 15 are reset the failure signals C 2 , C 1 and C 3 are at the high level, as illustrated in FIG. 6(e), 6(f) and 6(g), which indicates the detection of a malfunction.", "At the time instant t 2 , the reset signal RS 1 is raised to the high level, as illustrated in FIG. 6(b), and the reset state of the sub-microcomputer 20 is released.", "In the second mode, during the period t 2 -t 3 , while the sub-microcomputer 20 is not in the reset state, the sub-microcomputer 20 receives the failure signals C 1 and C 3 from the first and second main microcomputers 10 and 15 and generates the control signal A 2 , thereby causing the backup operation to occur.", "If, as in this case, the failure signals C 1 and C 3 are produced at the same time, the failure signal C 1 takes precedence, because the failure C 3 is inverted by the inverter 22.", "The output of the AND gate 23 is raised to the high level and the driver 14 is operated.", "Since the failure signal C 1 also operates the relay 12, the contacts 12a and 12b are switched and the exciting coil 13 is driven by the output of the driver 14, rather than being driven by the first main microcomputer 10.", "The potential between the driver 14 and the contact 12b is sampled as the diagnostic signal B 2a by the sub-microcomputer 20.", "Sub-microcomputer 20 diagnoses the condition of the driver 14 and the exciting coil 13 with respect to the control signal A 2 .", "When the diagnostic result indicates that the driver 14 or the exciting coil 13 is normal, the failure C 2 is set to the low level as indicated in the period t 3 -t 4 in FIG. 6(g).", "If an abnormal condition is detected, such as a breakage of the coil 13 or a bad driver 14, a failure signal C 2 is set to the low level momentarily as indicated in the period t 3 -t 4 in FIG. 6(h), and is then held at the high level.", "In the third mode, at the time t 4 , as illustrated in FIGS. 6(b) and 6(c), the reset signal RS 1 is set to the low level resetting the sub-microcomputer 20, while the reset signal RS 2 is raised to the high level.", "Therefore, the reset state of the first microcomputer 10 is released and the reset state of the second main microcomputer 15 is maintained.", "During the period t 4 -t 5 a diagnosis of the driver 11 and the exciting coil 13 is performed.", "When the diagnostic result indicates that the driver 11 and the exciting coil 13 are both normal, the failure signal C 1 is set to the low level at the time t 5 , as illustrated in FIG. 6(e).", "At the time t 6 , the reset signal RS 1 is set to the high level and only the second main microcomputer 15 is in the reset state.", "Accordingly, at the time t 6 only the failure signal C 3 is at the high level, as illustrated in FIG. 6(f), and the sub-microcomputer 20 starts the backup operation for the second main microcomputer 15 by generating the control signal A 2 .", "The failure signal C 3 is at the high level and therefore the output of the inverter 22, at the low level, is supplied through the OR gate 21 to the AND gate 24 via the inverter 25.", "Thus, the control signal A 2 drives the driver 19 through the AND gate 24.", "The contacts 17a and 17b of the relay 17 are also operated by the failure C 3 , so that the exciting coil 18 is driven by the output of the driver 19.", "The sub-microcomputer 20 samples, as the diagnostic signal B 2b , the potential at a point between the driver 19 and the contact 17b.", "If the diagnostic signal B 2b indicates a normal operation with respect to the control signal A 2 , the sub-microcomputer 20 generates a low level signal as the failure signal C 2 during the period t 7 -t 8 , as illustrated in FIG. 6(g).", "If the diagnostic signal B 2b indicates an abnormal operation, the sub-microcomputer 20 provides the failure signal C 2 at the high level, which set to the low level momentarily during the period t 7 -t 8 , as illustrated in FIG. 6(i).", "In the fourth mode, at the time t 8 , the reset RS 1 is set to the low level temporarily while the reset RS 3 is raised to the high level, and therefore, only the sub-microcomputer 20 is reset.", "The second main microcomputer 15 carries out the self diagnostic operation during the period t 8 -t 9 .", "If the self diagnostic signal indicates a normal operation, the failure signal C 3 is set to the low level at the time t 9 , as illustrated in FIG. 6(f).", "At the time t 10 the reset signal RS 1 is raised to the high level as illustrated in FIG. 6(b), and the reset state of the sub-microcomputer 20 is released.", "Thus, all the self-diagnostic operations of the queued redundant systems have been accomplished and all the microcomputers are in a normal operating state.", "In the self-diagnosis mode, operating currents are supplied to the exciting coils 13 and 18.", "However, since the self-diagnosis is achieved in a very short time, the elements to be controlled by the exciting coils 13 and 18 are not driven by the operating currents, that is, no adverse affects are caused by the operating currents flowing during the self-diagnosis mode.", "Thus, the failure signal C 2 which represents the condition of the sub-control system is applied to alarm circuit 34.", "The alarm circuit 34 detects the wave forms during the periods t 3 -t 4 , as illustrated in FIG. 6(h), or during the time period t 7 -t 8 , as illustrated in FIG. 6(i), to produce the alarm signal AL.", "An alarm circuit 34 discrimination operation will be described with reference to FIG. 4 and FIGS. 7-10.", "When the initial signal IS generated by the initial signal generating circuit 26 (FIG.", "2) is supplied to the flip-flops 38 and 39, illustrated in FIG. 4, they are reset.", "The failure signal C 2 output bv the sub-microcomputer 20 through the output port O b2 (FIG.", "2), and is applied to the D input terminals of the flip-flop circuits 38 and 39 (FIG.", "4) after being delayed by the delay circuit 37 for a time period ΔT.", "The reset signals RS 2 and RS 3 are applied to the clock input terminals CLK of the flip-flop circuits 38 and 39, respectively.", "The flip-flop circuits 38 and 39 carry out the discrimination operation based on the presence or absence of the failure signal C 2 which is supplied through the delay circuit 37 during the period that the high level reset signals RS 2 and RS 3 are supplied.", "When the failure signal C 2 , during a normal period, is supplied to the flip-flop circuits 38 and 39 after being delayed by the delay circuit 37 for the time ΔT, as illustrated in FIG. 7(a), the input signal applied to the D terminal of the flip-flop circuit 38 is at the low level, i.e., being delayed as illustrated in FIG. 7(a), at the time t 4 when the reset signal RS 2 rises, as illustrated in FIG. 7(b).", "Accordingly, the flip-flop circuit 38 is not set and the set output Q is maintained at the low level.", "Therefore, no high level alarm signal AL is output by OR gate 40, as illustrated in FIG. 7(c).", "When a failure signal C 2 , as illustrated in FIG. 6(h), indicating the abnormal condition of the driver 14 or the exciting coil 13 during the period t 2 -t 7 , is supplied to the D input terminals of the flip-flop circuits 38 and 39 via the delay circuit 37, as i11ustrated in FIG. 8(a), the flip-flop circuit 38 is reset at the time t 4 when the reset signal RS 2 rises.", "Thus, the set output Q of the flip-flop circuit 38 outputs through the OR gate 40 the high level of the alarm signal AL signalling that the queued redundant system is abnormal, as illustrated in FIG. 8(c).", "When the failure signal C 2 , indicating the normal operation of the driver 19 and the exciting coil 18, is supplied to the alarm circuit, the low level of the failure signal C 2 is delayed at the time t 8 , as illustrated in FIG. 9(a).", "The failure signal C 2 is at a low level when the reset signal RS 3 rises and is raised to the high level, as illustrated in FIG. 9(b).", "Therefore, the flip-flop circuit 39 is not set and the output produced by the OR gate 40 is maintained at the low level, as illustrated in FIG. 9(c).", "When the driver 19 and the exciting coil 18 are malfunctioning the failure signal C 2 is supplied through the delay circuit 37, as illustrated in FIG. 10(a).", "The failure signal C 2 is at the high level at the time t 8 when the reset signal RS 3 rises and is raised to the high level, and therefore, the flip-flop circuit 39 is set as illustrated in FIG. 10(b).", "As a result, the OR gate 40 which receives the output produced by the set output Q of the flip-flop circuit 39 outputs the high level of the alarm signal AL, as illustrated in FIG. 10(c), signalling that the queued redundant system is abnormal.", "FIG. 11 is a flow chart illustrating the self-diagnostic operation of the queued redundant system.", "Block 1 indicates that when the power is applied, one of the failure signals generated by the main control systems is set to the low level.", "Block 2 indicates that the sub-control system produces a control signal causing the backup operation for one of the main control systems to begin.", "Block 3 indicates that the sub-control system performs the self-diagnostic operation and block 4 is a branch box in which the branch selected depends upon the diagnostic result.", "Block 5 indicates that the sub-control system for the backup operation for the main microcomputer system is performing normally and the failure signal is set to the high level.", "The backup operation for the first or second main microcomputer 10 or 15 by the sub-microcomputer 20 will be described.", "When the driver 11 fails, i.e., becomes abnormal, the first main microcomputer 10 detects the abnormal condition of the diagnostic signal B 1 with respect to a control signal A 1 and outputs a failure signal C 1 .", "When failure signal C 1 is output, the relay 12 is activated, and the exciting coil 13 is connected to the driver 14 in the sub-control system.", "Furthermore, on the production of the failure signal C 1 , the sub-microcomputer 20 produces the control signal A 2 .", "Since the output of the OR gate 21 has been raised to the high level by the failure signal C 1 the control signal A 2 is passed through the AND gate 23 to the driver 14.", "Thus, the driver 14 is operated by the control signal A 2 and the exciting coil 13 is driven by the output of the driver 14 and the backup operation is accomplished.", "This backup operation is similarly performed for the second main microcomputer 15.", "When the first and second main microcomputers 10 and 15 provide the failure signals C 1 and C 2 at the same time, the first main microcomputer 10 takes precedence in the backup operation over the second main microcomputer 15 because of the signal control means including the OR gate 21, the inverters 22 and 25, and the AND gates 23 and 24.", "In the above described embodiment, there is only one queued redundant system, i.e. one sub-microcomputer 20, which backs up two main control systems.", "However, it should be noted that the number of main control systems can be selected as desired.", "As is apparent in the above description, in the control system according to the present invention, when the power is turned on, the main control systems and the sub-control system are reset.", "Then the reset state of the sub-control system is released so that a failure signal is produced by one of the main control systems in order to momentarily cause a backup operation.", "During this backup operation, self-diagnostics are performed by the sub-control system under predetermined conditions.", "Thus, whenever the power source is turned on, the self-diagnostic functions of the sub-control system are effected.", "As can be seen from the above description, the present control system having the self-diagnostic function is simple in arrangement and high in reliability.", "The many features and advantaqes of the invention are apparent from the detailed specification and thus it is intended by the appended claims to cover all such features and advantages of the system which fall within the true spirit and scope of the invention.", "Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention." ]
INTRODUCTION AND BACKGROUND The present invention relates to a method for producing metallic powders in micron and submicron size. The metallic powders are particularly useful for electronic applications. Metallic powders in micron size range have many special applications including dental materials, medical prosthetics, catalysts, electronic devices such as multilayer capacitors, integrated circuits and structural applications in the aircraft industry. Purity, controlled particle size and morphology are often essential for many applications. Smooth spherical particles of palladium (Pd), silver (Ag) and palladium/silver (Pd/Ag) alloys, nickel (Ni) and gold (Au) in 0.5 to 2.0 micrometer size range are needed for multilayer capacitors. For this use, it is essential to limit the onset of oxidation to a temperature above 400°C. and at the same time the total oxidation must also be below a few percent. The presence of too many small particles (0.3 microns and smaller) is undesirable because of their high surface to volume ratio which makes them more susceptible to higher levels of oxidation. Also, particles larger than 2 microns are to be avoided so that a thin smooth layer may be printed by screen printing employing pastes made with these powders. Particle size in the micrometer range, spherical shapes, crystallinity and purity and lack of voids in particles are essential qualities of the powders for electronic applications such as in multilayer capacitors. Spray decomposition of solution droplets of precursor compounds is an attractive process because of simple apparatus and equipment design and ability to operate in a continuous mode. The prior art has developed a number of methods for producing small particle metal powders. For example, Nagashima et al. (J. Material Research, 1987) produced nickel powders by spraying nickel nitrate and chloride solutions followed by in-flight treatment at 900-1600°C. in an H 2 /N 2 atmosphere. Temperatures above 1500° C. were necessary to obtain smooth spheres. Stopic et al. (1996)--(I.J. of Powder Metallurgy, Vol. 32, pp. 59-65) used long residence times of the order of 20 seconds to obtain smooth spheres at lower temperature in the range of 800-900° C. At lower temperatures, a significant amount of nickel oxide, an undesirable by-product, was observed. Although complete conversion to nickel at 900° C. was reported, crystallization was not complete. Hollow spheres were also observed. Asada et al. (JP 62-1807, 1987) describe a method for production of powders of Ag, Pd and their alloys by decomposition of sprays at temperatures well above the melting point of the metals. Asada et al. (JP Kokai 6-172802, November 1992) mention the addition of trace quantities of calcium and similar elements in producing Pd powder resistant to oxidation. Kodas et al. (U.S. Pat. No. 5,429,657, July 1995) disclose a method for producing powder of Pd, Ag and their alloys at temperatures significantly lower than the melting point of the metal but at long residence times of 9-20 seconds. The aerosol concentrations were limited to a value which might result in a 10% reduction in concentration by coagulation. Glicksman et al. (U.S. Pat. No. 5,616,165, April 1997; European Application EP 0761349 A1) extended the same method as Kodas et al. (U.S. Pat. No. 5,429,657, July 1995) to producing gold (Au) powder wherein the operating temperature is below the melting point of gold. An object of the present invention is to provide an improved method for obtaining micrometer size and submicrometer size metallic powders. SUMMARY OF THE INVENTION In achieving the above and other objects, the invention involves an economical process and associated equipment for commercial manufacture of controllable submicrometer size metallic powders for electronic and other applications. The method of the invention is based on the preparation of a stable high concentration precursor solution, production of a high density aerosol mist of the precursor solutions, selection of mist droplets with upper and lower size bounds, controlled drying of the droplets, their conversion to metallic powder in a high temperature gaseous atmosphere and the separation of the powders from carrier gases without significant loss inside the process equipment. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further understood with reference to the drawings, wherein: FIG. 1 is a schematic flow diagram of the process of the invention; FIG. 2 is a schematic view of a large droplet separator apparatus used in the process of the invention; FIG. 3 is a schematic view of a small droplet remover and concentrator; FIG. 4 is a schematic view of a cooler used in the present invention; FIG. 5A is a graph of particle size distribution with large droplet separator; FIG. 5B is a graph of particle size distribution without large droplet separator; FIG. 6 is an electron photomicrograph of the powder of example 1, FIG. 7 is an x-ray diffraction pattern of the powder of example 1; FIG. 8 is an electron photomicrograph of the powder produced with no heat in the dryer; and FIG. 9 is an electron photomicrograph of powder produced with heat in the dryer. DETAILED DESCRIPTION OF THE INVENTION The process and apparatus described in this invention are especially useful for producing finely divided, spherically shaped, non-hollow, fully densified particles in the micrometer and submicrometer size ranges with selectable upper and lower size cuts. More particularly, the present invention enables the control of the nature of the final metal or metal alloy product particle so as to obtain particles with a size distribution of from about 0.3 to 2 microns. Also the invention allows commercial production at low costs because of the energy savings realized by increase in the precursor concentration, number concentration of droplets in the carrier gas and by minimization of process losses to the walls of the process vessel and piping. A schematic flow diagram of the process of the invention is shown in FIG. 1. As used herein, the term "metal" is intended to include metal alloys as well. A stable precursor solution containing high metal concentration is desirable to achieve high product output. For silver, palladium and their mixtures, metal loadings higher than possible in simple aqueous solutions of their nitrates, are achieved using the first feature of this invention--addition of excess free nitric acid. The high concentration precursor solution is prepared by dissolution of soluble ingredients in water or dissolution of metal in acids, rather than by dispersion of solid components. The increase in the metal content of the solution has the direct effect of increasing the output. The metal precursor compounds can be nitrate salts, or salts of mineral or organic acids, but metal nitrates have primarily been used. These compounds are referred to herein as thermally decomposable precursor compounds. The solutions thereof are formed in thermally volatilizable solvents. By the term "high metal concentration", we mean a range of 5 to 35% by weight metal content. Although nitric acid is preferred other mineral acids such as hydrochloric acid can be used to form the solution provided the resulting metal precursor compound is soluble in the solvent for spraying. Nitric acid concentration is expressed in terms of weight %, and is based on the total amount of material in the sprayed solution. Also, the total concentration of Pd metal is up to 30% There is no minimum concentration of metal in the solution, but the rate of production of metal drops as the concentration is reduced, so it is normally kept rather high for practical reasons. As shown by the schematic flow diagram in FIG. 1, the liquid solution containing the thermally decomposable metal precursor compound is maintained in a reservoir (1) and transferred to the mist producing device (3) such as an acoustic or gas driven or a pressure atomizer. Atomizers of this nature are commercially available. An ultrasonic atomizer widely used for atomization of water for humidification purposes is very suitable for practice of the invention provided it is constructed of corrosion resistant material. Various techniques have been used to atomize the solution disclosed herein, such as two-fluid nozzles, high pressure nozzles, Collison nebulizers, filter element aerosol generators and the like. The mist producing device forms an aerosol with the carrier gas consisting essentially of finely divided droplets of the sprayed solution of the thermally decomposable metal precursor compounds in the carrier gas. Carrier gas such as air or nitrogen as well as other gases, such as argon, hydrogen, carbon monoxide, or mixtures thereof necessary for conversion of the precursors to metal are introduced from the reservoir (2) to the mist generator (3). Mixtures of gases such as nitrogen and hydrogen as a forming gas for reduction of metals are particularly suitable. The resulting aerosol is conveyed to the particle size selector and concentrator (4) via entrainment in the carrier gas flow. After flowing through the particle size selector and concentrator (4), the mist proceeds through a controlled drying section (5). The dryer removes the solvent which, in most cases, is water thereby producing particles made up of the soluble metal salt, such as a nitrate. After drying, the aerosol flows to the reactor zone (6) for the conversion to the metallic, densified powder. The product particles are then cooled in the cooler section (7) and flow to the product collector (8). Carrier gases are scrubbed in scrubber (9) and vented or recovered, indicated by the vertical line and horizontal line, respectively. In the reactor there is a thermal decomposition or a reaction between the particle and the gaseous component. For example, hydrogen reacts with nickel oxide formed by decomposition of nitrate. In general, the solvent is completely removed in the drying stage in a controlled drying determined by experiment. Thus, the best control of the drying rate avoids conditions that would be so high as to form hollow shells or fragments. The particle size selector and concentrator (4) is shown in greater detail in FIG. 2. The large particle separator consists of a machined cup (12) with internal taper of up to 60 degrees. It is attached to the base of a cylindrical tube (13) of diameter D 1 using screws (14) and the tube is separated from the cup by a distance `s` using spacers (15). The internal diameter of the cup at the same level as the base of the tube is D 2 . The gap between the cup and the tube is W and is equal to (D 2 -D 1 )/2. Mist droplets larger than the desired size are removed by inertial separation causing them to collect in the cup (12) and are drained back to the mist generator (3). The separation of particles by size is based on their inertia. A larger particle has higher mass and requires more force to change direction. In a steady stream of the mist or an aerosol (16), the particles flow with the carrier gas following the gas streamlines until there is a change in direction caused by an obstacle such as a plate or a bend in a pipe. Large particles tend to continue in the same flow direction while the gas exerts force to change the direction. As a result the larger particles lag and deviate more from the gas flow as compared to smaller particles and gas molecules. The separation is controlled by a combination of the flow velocity, the dimension of the flow passage and the geometry of the obstacle. The separation is effected by adjusting the characteristic opening "W" in FIG. 2 which is related to the dimensionless "Stokes Number" governing the inertial separation as follows ##EQU1## where d s is droplet size in centimeters (cm.), μ is viscosity in poise, ρ s is solution density in g/cc, C c is the Cunningham slip correction=1.0 for the normal range of droplet sizes used, U is the average velocity in cm/s, and W is the characteristic opening in cm equal to (D 2 -D 1 )/2. If "Q" is the air flow rate in liters per min., the velocity U in cm/s is related to W by the equation: U·π/4·(D.sub.2.sup.2 -D.sub.1.sup.2)=1000·Q/60(II) or for D 2 -D 1 U·πD.sub.1 ·W=1000·Q/60 or U=(1000·Q/60)πD.sub.1 ·W or, for D 1 =15 cm(6") U=0.353 Q/W For an annular jet, the square root of the Critical Stokes Number N Stkc is of the order of 0.7 and the Design Equation for selector is ##EQU2## The Stokes Number "N Stk " is a convenient way to account for all the important quantities for particle separation. In the Equation I for the Stokes Number the variable U--the velocity and W the gap determine the particle diameter at separation and the Stokes number these conditions is called the Critical Stokes Number. The other quantities, μ--the viscosity and p s --the solution density are generally fixed. The terms U and W are related to each other for a given flow rate as indicated by the Equation II. Once the particle size for separation is chosen and the gas flow rate selected, the required gap width W is calculated using the Equation III. Thus, the separator can be tuned by adjusting only the gap W for the desired gas flowrate which in turn sets the production rate. In the device depicted in FIG. 2, (symbols included in the accompanying drawing) the droplet size separation may be adjusted by varying the distance `s` by addition of spacers and thus proportionately changing the gap W. The large droplets impacting on the solid surface of the separator accumulate in the cup and flow back into the mist generator through the liquid drain (17). The second stage of the selector/concentrator also consists of an inertial separator. The aerosol mist flow is divided into two flows as shown in the virtual impactor (18) of FIG. 3. The virtual impactor shown in FIG. 3 is used to remove smaller particles in the second stage. The term is used in aerosol science and technology literature to represent the flow obstacle as being a stationary or slow moving gas rather than a solid surface usually used in "normal" impactors. The separation is still based on inertia. The aerosol spray (19) from the large particle separator may be concentrated, and particles smaller than 0.5 micrometers may be removed using the virtual impactor shown in FIG. 3. The aerosol flow is accelerated in the primary jet (20) of diameter d j and aimed at another jet (21), the minor flow jet, with slightly larger diameter d m . The flow through this jet is maintained at only a fraction (typically 1/10th) of the total flow and is called the minor flow. The rest of the flow--the major flow (22) (typically 9/10th)--goes around the minor flow conduit (21) through the annular space. The larger particles have higher inertia and remain entrained in the minor flow. This results in an increased concentration of larger particles. The small particles remain entrained in all of the gas, and those in the major flow are removed from the aerosol stream (23) flowing to the reactor. Some smaller particles stay in the minor flow, but significant removal (typically 90%) of small particles is possible. The second stage also achieves increased droplet concentration because of the reduced amount of the carrier gas, a feature desirable to reduce the heating energy requirement. The mist then flows through a heated tube serving as a controlled drying section (5) maintained at a minimum temperature between 50 to 150° C. and above the dew point of the flowing gas and vapor mixture. The dryer tube is heated by electric resistance heaters. Controlled drying with a residence time on the order of a second or more is essential to avoid formation of a crust of dried material which may cause formation of hollow shells or collapsed balloons or tiny fragments produced by shattering of the droplets. Proper drying residence time is achieved by trial and error through experimentation within the skill of the art. Residence time is determined by the velocity of the material flowing through the system, as well as the length of the drying section. The dry aerosol then flows through the reactor zone (6) where conversion to the final metal product takes place. The temperature of the reactor and the residence times are controlled to yield a product containing near spherical shaped particles whose size is related to the droplet size by the following relation IV. The reactor zone is a refractory hot-wall tube which is contained in a furnace that is heated by gas or electrically. The unidentified line coming off the cooler (7) is the cold gas injection. The cooler utilizes a porous inner tube surrounded by an air jacket. The droplet size d s is related to the final metal particle size d p by the equation: (Metal Density·πdp.sup.3 =ρ.sub.s ·π·d.sub.s.sup.3) IV In the first stage of the Separator (shown in FIG. 2), the mist droplets of a size such that will result in final solid particles 2 micrometers in diameter are separated. The relevant droplet size is calculated by the Equation IV by knowledge of densities and concentration of the metal in the starting solution. The product particles exiting the reactor are cooled in the section (7) to lower temperatures compatible with the filter media used in the product recovery bag or cartridge filter (8). The cooler/diluter (24) of a unique design (shown in FIG. 4) achieves the cooling of the product and the carrier gas (25) as well as prevention of particle loss to walls of the cooling section. The hot gas and product particles from the furnace enter in the center of a cylindrical section (26). Cooling gas (27) enters radially inwards through a concentric porous tube (28) counteracting the tendency of particles to move towards the cooler walls because of a phenomenon known as thermophoresis which may result in loss of up to 20% of the product particles. The cooler/diluter (24) consists of a porous tube (28) jacketed by a solid wall tube (29). Cooling gas (27) is supplied to the jacket and flows inwards from the porous tube walls. After mixing of the hot gas flow from the furnace and the cooling gas the total temperature is reduced to a sufficiently low value typically below 200° C. This "transpiration flow" of the gas keeps the product particles away from the walls. The product particles (30) are collected in a fabric filter (not shown) in the form of a cake deposited on bags of cartridges made out of a filter media such as Goretex® coated Teflon® felt. The powder product is released from bags into a hopper by a reverse flow caused by a pulsed gas jet or shaking. The particle collector is a conventional structure. Other conventional devices such a cyclone separator or an electrostatic precipitator may be used alone or in addition to the filter. The carrier gas and other reaction products exiting the filter are scrubbed in section (9) to remove contaminants such as oxides of nitrogen, nitric acid vapors and/or hydrogen chloride. The carrier gases and acids can be purified and recycled. The product particle produced by the present invention is not hollow as hollow particles are generally considered undesirable for most uses. The particles of this invention are fully densified, that is, dense throughout their composition. The following examples will serve to illustrate more detailed aspects of the invention. EXAMPLE 1 A stable solution of silver and palladium nitrates containing 9% metal at a silver to palladium ratio of 30:70 was prepared by addition of excess nitric acid so as to yield 36% free acid. The solution was atomized by an acoustic device operating at a frequency of 1.7 MHz. The acoustic device consists of a number of piezo electric transducers and circuits made by American Piezo Ceramic (APC) Company for humidification equipment. A carrier gas flow of 20 liters per minute was used. The residence time in the high temperature zone (6) was of the order of 1 second. Particles were produced with and without the use of the separator. To remove all droplets resulting in palladium particles over 2 micrometers, the cut size should be 1 micrometer, the solution droplet size to be removed is obtained by using p s =1.38 g/cc. and is equal to 4.6 μm. The gap width W is obtained by substituting d sc =4.2, U by Equation II, ρ s =1.38, and μ=1.8·10E-4 poise. W=2.59·10 -4 ·Q and for the 20 liters per minute flow W=0.33 mm. The mist exiting the separator was dried to obtain nitrate particles at a temperature of 150° C. and then flowed through the reactor tube maintained at 1400° C. The residence time was 2 seconds. The powder converted to metal and was collected in Teflon coated filter bags maintained at a temperature of 120° C. Powder sample was collected with and without the first stage of the selector. Particle size was determined using a Leeds and Northrupp Microtrac instrument. The sample with separator in place contained essentially no particles over 2 micrometers, while a sample without the separator contained several large particles as seen from FIGS. 5A and 5B, respectively. A micrograph of the particles is shown in FIG. 6. An X-ray diffraction spectrum of the powder is shown in FIG. 7 and indicates the particles are true alloys with excellent crystallinity. EXAMPLE 2 An illustration of the effect of controlled drying on powder properties was explored. Starting with a precursor mixed solution of Pd and Ag--nitrates to yield a product with 60% Pd and a 40% Ag content, a mist was generated in section (3) of FIG. 1. The mist passed through the large droplet separator (4) and through the dryer (5). The mist then was subjected to a maximum temperature of 1000° C. to complete product conversion which was then collected in the filter (8). In the first run represented by an electron micrograph of the particles as FIG. 8, the mist was not subjected to heat in the dryer section. As a result, the droplets entering the reactor were wet. In the second run represented by FIG. 9, the droplets were dried in heating section (5) so that the temperature of the mist entering the reactor was at 130° C., at which temperature the mist particles were completely dry. FIG. 8 shows the presence of smaller particles attached to the normally smooth particles, while only the normal particles are seen in FIG. 9. The presence of the smaller particles below 0.3 micrometers is undesirable in several applications as they degrade the electronic properties of the powder and show a tendency to oxidize at lower temperature. EXAMPLE 3 The following example illustrates the benefits of achieving higher particle concentration in the carrier gases. The agglomeration of particles results in hard aggregates if the temperature is high and the degree of aggregation is dependent on the self-diffusion coefficient of the product metal and the residence time. The degree of aerosol coagulation resulting in particle contacts is expressed as 1/n-1/n.sub.o =K·t or n.sub.o /n=1+K·t n.sub.o where n is the number concentration at time t in #/cc, n o is the initial number concentration #/cc, K is the Smoluchowski coagulation coefficient cc/s, and t is time in seconds. At a temperature of 1400° C. in the conversion zone, the value of the coagulation coefficient is of the order 10 -8 cc/s. If the initial concentration is of the order 10 8 #/cc, in one second the concentration will drop by a factor of 2 resulting in a size increase of about 20%, and in 10 seconds the concentration will drop by a factor of 11, resulting in a size increase by a factor of 2.3. Thus, a residence time of 1 second in the high temperature zone will allow higher concentration than possible for a residence time of 10 seconds. This results in significant savings in the energy costs. Our calculations show that reduction of residence time from 10 seconds utilized by Kodas et al. to 1 second in accordance with the invention will allow a ten-fold permissible increase in droplet number concentration to maintain the same level of agglomeration. A wide range of metallic powder can be prepared in accordance with this invention. The above examples shows specific materials used in the process of this invention. Other noble metals and base metals can be used with appropriate conditions. Examples are Pt, Ag, Cu, Ni, Co, Ni, Ru and Ta, as well as alloys. Particle size of a few microns or less is a largely known and proven requirement for multi-layer capacitor electrode materials. Larger particles are known to cause shorting of the parts by penetrating too far into, or through, the dielectric material layer. As far as the lower end of the size range is concerned, there is no lower limit to size, but smaller particles are known to be more reactive and sinter at lower temperatures, so it is common practice to limit the number of very small particles in order to avoid such problems. Further variations and modifications will become apparent to those skilled in the art from the foregoing and are intended to be encompassed by the claims appended hereto.
An economical process and associated hardware for commercial manufacture of controllable submicrometer size metallic powders for electronic and other applications. The method is based on the preparation of a stable high concentration precursor solution, production of a high density aerosol mist of the precursor solutions, selection of mist droplets with upper and lower size bounds, controlled drying of the droplets, their conversion to metallic powder in a high temperature gaseous atmosphere and the separation of the powders from carrier gases without significant loss inside the process hardware.
Condense the core contents of the given document.
[ "INTRODUCTION AND BACKGROUND The present invention relates to a method for producing metallic powders in micron and submicron size.", "The metallic powders are particularly useful for electronic applications.", "Metallic powders in micron size range have many special applications including dental materials, medical prosthetics, catalysts, electronic devices such as multilayer capacitors, integrated circuits and structural applications in the aircraft industry.", "Purity, controlled particle size and morphology are often essential for many applications.", "Smooth spherical particles of palladium (Pd), silver (Ag) and palladium/silver (Pd/Ag) alloys, nickel (Ni) and gold (Au) in 0.5 to 2.0 micrometer size range are needed for multilayer capacitors.", "For this use, it is essential to limit the onset of oxidation to a temperature above 400°C.", "and at the same time the total oxidation must also be below a few percent.", "The presence of too many small particles (0.3 microns and smaller) is undesirable because of their high surface to volume ratio which makes them more susceptible to higher levels of oxidation.", "Also, particles larger than 2 microns are to be avoided so that a thin smooth layer may be printed by screen printing employing pastes made with these powders.", "Particle size in the micrometer range, spherical shapes, crystallinity and purity and lack of voids in particles are essential qualities of the powders for electronic applications such as in multilayer capacitors.", "Spray decomposition of solution droplets of precursor compounds is an attractive process because of simple apparatus and equipment design and ability to operate in a continuous mode.", "The prior art has developed a number of methods for producing small particle metal powders.", "For example, Nagashima et al.", "(J.", "Material Research, 1987) produced nickel powders by spraying nickel nitrate and chloride solutions followed by in-flight treatment at 900-1600°C.", "in an H 2 /N 2 atmosphere.", "Temperatures above 1500° C. were necessary to obtain smooth spheres.", "Stopic et al.", "(1996)--(I.J. of Powder Metallurgy, Vol. 32, pp. 59-65) used long residence times of the order of 20 seconds to obtain smooth spheres at lower temperature in the range of 800-900° C. At lower temperatures, a significant amount of nickel oxide, an undesirable by-product, was observed.", "Although complete conversion to nickel at 900° C. was reported, crystallization was not complete.", "Hollow spheres were also observed.", "Asada et al.", "(JP 62-1807, 1987) describe a method for production of powders of Ag, Pd and their alloys by decomposition of sprays at temperatures well above the melting point of the metals.", "Asada et al.", "(JP Kokai 6-172802, November 1992) mention the addition of trace quantities of calcium and similar elements in producing Pd powder resistant to oxidation.", "Kodas et al.", "(U.S. Pat. No. 5,429,657, July 1995) disclose a method for producing powder of Pd, Ag and their alloys at temperatures significantly lower than the melting point of the metal but at long residence times of 9-20 seconds.", "The aerosol concentrations were limited to a value which might result in a 10% reduction in concentration by coagulation.", "Glicksman et al.", "(U.S. Pat. No. 5,616,165, April 1997;", "European Application EP 0761349 A1) extended the same method as Kodas et al.", "(U.S. Pat. No. 5,429,657, July 1995) to producing gold (Au) powder wherein the operating temperature is below the melting point of gold.", "An object of the present invention is to provide an improved method for obtaining micrometer size and submicrometer size metallic powders.", "SUMMARY OF THE INVENTION In achieving the above and other objects, the invention involves an economical process and associated equipment for commercial manufacture of controllable submicrometer size metallic powders for electronic and other applications.", "The method of the invention is based on the preparation of a stable high concentration precursor solution, production of a high density aerosol mist of the precursor solutions, selection of mist droplets with upper and lower size bounds, controlled drying of the droplets, their conversion to metallic powder in a high temperature gaseous atmosphere and the separation of the powders from carrier gases without significant loss inside the process equipment.", "BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further understood with reference to the drawings, wherein: FIG. 1 is a schematic flow diagram of the process of the invention;", "FIG. 2 is a schematic view of a large droplet separator apparatus used in the process of the invention;", "FIG. 3 is a schematic view of a small droplet remover and concentrator;", "FIG. 4 is a schematic view of a cooler used in the present invention;", "FIG. 5A is a graph of particle size distribution with large droplet separator;", "FIG. 5B is a graph of particle size distribution without large droplet separator;", "FIG. 6 is an electron photomicrograph of the powder of example 1, FIG. 7 is an x-ray diffraction pattern of the powder of example 1;", "FIG. 8 is an electron photomicrograph of the powder produced with no heat in the dryer;", "and FIG. 9 is an electron photomicrograph of powder produced with heat in the dryer.", "DETAILED DESCRIPTION OF THE INVENTION The process and apparatus described in this invention are especially useful for producing finely divided, spherically shaped, non-hollow, fully densified particles in the micrometer and submicrometer size ranges with selectable upper and lower size cuts.", "More particularly, the present invention enables the control of the nature of the final metal or metal alloy product particle so as to obtain particles with a size distribution of from about 0.3 to 2 microns.", "Also the invention allows commercial production at low costs because of the energy savings realized by increase in the precursor concentration, number concentration of droplets in the carrier gas and by minimization of process losses to the walls of the process vessel and piping.", "A schematic flow diagram of the process of the invention is shown in FIG. 1. As used herein, the term "metal"", "is intended to include metal alloys as well.", "A stable precursor solution containing high metal concentration is desirable to achieve high product output.", "For silver, palladium and their mixtures, metal loadings higher than possible in simple aqueous solutions of their nitrates, are achieved using the first feature of this invention--addition of excess free nitric acid.", "The high concentration precursor solution is prepared by dissolution of soluble ingredients in water or dissolution of metal in acids, rather than by dispersion of solid components.", "The increase in the metal content of the solution has the direct effect of increasing the output.", "The metal precursor compounds can be nitrate salts, or salts of mineral or organic acids, but metal nitrates have primarily been used.", "These compounds are referred to herein as thermally decomposable precursor compounds.", "The solutions thereof are formed in thermally volatilizable solvents.", "By the term "high metal concentration", we mean a range of 5 to 35% by weight metal content.", "Although nitric acid is preferred other mineral acids such as hydrochloric acid can be used to form the solution provided the resulting metal precursor compound is soluble in the solvent for spraying.", "Nitric acid concentration is expressed in terms of weight %, and is based on the total amount of material in the sprayed solution.", "Also, the total concentration of Pd metal is up to 30% There is no minimum concentration of metal in the solution, but the rate of production of metal drops as the concentration is reduced, so it is normally kept rather high for practical reasons.", "As shown by the schematic flow diagram in FIG. 1, the liquid solution containing the thermally decomposable metal precursor compound is maintained in a reservoir (1) and transferred to the mist producing device (3) such as an acoustic or gas driven or a pressure atomizer.", "Atomizers of this nature are commercially available.", "An ultrasonic atomizer widely used for atomization of water for humidification purposes is very suitable for practice of the invention provided it is constructed of corrosion resistant material.", "Various techniques have been used to atomize the solution disclosed herein, such as two-fluid nozzles, high pressure nozzles, Collison nebulizers, filter element aerosol generators and the like.", "The mist producing device forms an aerosol with the carrier gas consisting essentially of finely divided droplets of the sprayed solution of the thermally decomposable metal precursor compounds in the carrier gas.", "Carrier gas such as air or nitrogen as well as other gases, such as argon, hydrogen, carbon monoxide, or mixtures thereof necessary for conversion of the precursors to metal are introduced from the reservoir (2) to the mist generator (3).", "Mixtures of gases such as nitrogen and hydrogen as a forming gas for reduction of metals are particularly suitable.", "The resulting aerosol is conveyed to the particle size selector and concentrator (4) via entrainment in the carrier gas flow.", "After flowing through the particle size selector and concentrator (4), the mist proceeds through a controlled drying section (5).", "The dryer removes the solvent which, in most cases, is water thereby producing particles made up of the soluble metal salt, such as a nitrate.", "After drying, the aerosol flows to the reactor zone (6) for the conversion to the metallic, densified powder.", "The product particles are then cooled in the cooler section (7) and flow to the product collector (8).", "Carrier gases are scrubbed in scrubber (9) and vented or recovered, indicated by the vertical line and horizontal line, respectively.", "In the reactor there is a thermal decomposition or a reaction between the particle and the gaseous component.", "For example, hydrogen reacts with nickel oxide formed by decomposition of nitrate.", "In general, the solvent is completely removed in the drying stage in a controlled drying determined by experiment.", "Thus, the best control of the drying rate avoids conditions that would be so high as to form hollow shells or fragments.", "The particle size selector and concentrator (4) is shown in greater detail in FIG. 2. The large particle separator consists of a machined cup (12) with internal taper of up to 60 degrees.", "It is attached to the base of a cylindrical tube (13) of diameter D 1 using screws (14) and the tube is separated from the cup by a distance `s` using spacers (15).", "The internal diameter of the cup at the same level as the base of the tube is D 2 .", "The gap between the cup and the tube is W and is equal to (D 2 -D 1 )/2.", "Mist droplets larger than the desired size are removed by inertial separation causing them to collect in the cup (12) and are drained back to the mist generator (3).", "The separation of particles by size is based on their inertia.", "A larger particle has higher mass and requires more force to change direction.", "In a steady stream of the mist or an aerosol (16), the particles flow with the carrier gas following the gas streamlines until there is a change in direction caused by an obstacle such as a plate or a bend in a pipe.", "Large particles tend to continue in the same flow direction while the gas exerts force to change the direction.", "As a result the larger particles lag and deviate more from the gas flow as compared to smaller particles and gas molecules.", "The separation is controlled by a combination of the flow velocity, the dimension of the flow passage and the geometry of the obstacle.", "The separation is effected by adjusting the characteristic opening "W"", "in FIG. 2 which is related to the dimensionless "Stokes Number"", "governing the inertial separation as follows ##EQU1## where d s is droplet size in centimeters (cm.), μ is viscosity in poise, ρ s is solution density in g/cc, C c is the Cunningham slip correction=1.0 for the normal range of droplet sizes used, U is the average velocity in cm/s, and W is the characteristic opening in cm equal to (D 2 -D 1 )/2.", "If "Q"", "is the air flow rate in liters per min.", ", the velocity U in cm/s is related to W by the equation: U·π/4·(D.", "sub[.", "].2.", "sup[.", "].2 -D.", "sub[.", "].1.", "sup[.", "].2)=1000·Q/60(II) or for D 2 -D 1 U·πD.", "sub[.", "].1 ·W=1000·Q/60 or U=(1000·Q/60)πD.", "sub[.", "].1 ·W or, for D 1 =15 cm(6") U=0.353 Q/W For an annular jet, the square root of the Critical Stokes Number N Stkc is of the order of 0.7 and the Design Equation for selector is ##EQU2## The Stokes Number "N Stk "", "is a convenient way to account for all the important quantities for particle separation.", "In the Equation I for the Stokes Number the variable U--the velocity and W the gap determine the particle diameter at separation and the Stokes number these conditions is called the Critical Stokes Number.", "The other quantities, μ--the viscosity and p s --the solution density are generally fixed.", "The terms U and W are related to each other for a given flow rate as indicated by the Equation II.", "Once the particle size for separation is chosen and the gas flow rate selected, the required gap width W is calculated using the Equation III.", "Thus, the separator can be tuned by adjusting only the gap W for the desired gas flowrate which in turn sets the production rate.", "In the device depicted in FIG. 2, (symbols included in the accompanying drawing) the droplet size separation may be adjusted by varying the distance `s` by addition of spacers and thus proportionately changing the gap W. The large droplets impacting on the solid surface of the separator accumulate in the cup and flow back into the mist generator through the liquid drain (17).", "The second stage of the selector/concentrator also consists of an inertial separator.", "The aerosol mist flow is divided into two flows as shown in the virtual impactor (18) of FIG. 3. The virtual impactor shown in FIG. 3 is used to remove smaller particles in the second stage.", "The term is used in aerosol science and technology literature to represent the flow obstacle as being a stationary or slow moving gas rather than a solid surface usually used in "normal"", "impactors.", "The separation is still based on inertia.", "The aerosol spray (19) from the large particle separator may be concentrated, and particles smaller than 0.5 micrometers may be removed using the virtual impactor shown in FIG. 3. The aerosol flow is accelerated in the primary jet (20) of diameter d j and aimed at another jet (21), the minor flow jet, with slightly larger diameter d m .", "The flow through this jet is maintained at only a fraction (typically 1/10th) of the total flow and is called the minor flow.", "The rest of the flow--the major flow (22) (typically 9/10th)--goes around the minor flow conduit (21) through the annular space.", "The larger particles have higher inertia and remain entrained in the minor flow.", "This results in an increased concentration of larger particles.", "The small particles remain entrained in all of the gas, and those in the major flow are removed from the aerosol stream (23) flowing to the reactor.", "Some smaller particles stay in the minor flow, but significant removal (typically 90%) of small particles is possible.", "The second stage also achieves increased droplet concentration because of the reduced amount of the carrier gas, a feature desirable to reduce the heating energy requirement.", "The mist then flows through a heated tube serving as a controlled drying section (5) maintained at a minimum temperature between 50 to 150° C. and above the dew point of the flowing gas and vapor mixture.", "The dryer tube is heated by electric resistance heaters.", "Controlled drying with a residence time on the order of a second or more is essential to avoid formation of a crust of dried material which may cause formation of hollow shells or collapsed balloons or tiny fragments produced by shattering of the droplets.", "Proper drying residence time is achieved by trial and error through experimentation within the skill of the art.", "Residence time is determined by the velocity of the material flowing through the system, as well as the length of the drying section.", "The dry aerosol then flows through the reactor zone (6) where conversion to the final metal product takes place.", "The temperature of the reactor and the residence times are controlled to yield a product containing near spherical shaped particles whose size is related to the droplet size by the following relation IV.", "The reactor zone is a refractory hot-wall tube which is contained in a furnace that is heated by gas or electrically.", "The unidentified line coming off the cooler (7) is the cold gas injection.", "The cooler utilizes a porous inner tube surrounded by an air jacket.", "The droplet size d s is related to the final metal particle size d p by the equation: (Metal Density·πdp.", "sup[.", "].3 =ρ.", "sub.", "s ·π·d.", "sub.s.sup[.", "].3) IV In the first stage of the Separator (shown in FIG. 2), the mist droplets of a size such that will result in final solid particles 2 micrometers in diameter are separated.", "The relevant droplet size is calculated by the Equation IV by knowledge of densities and concentration of the metal in the starting solution.", "The product particles exiting the reactor are cooled in the section (7) to lower temperatures compatible with the filter media used in the product recovery bag or cartridge filter (8).", "The cooler/diluter (24) of a unique design (shown in FIG. 4) achieves the cooling of the product and the carrier gas (25) as well as prevention of particle loss to walls of the cooling section.", "The hot gas and product particles from the furnace enter in the center of a cylindrical section (26).", "Cooling gas (27) enters radially inwards through a concentric porous tube (28) counteracting the tendency of particles to move towards the cooler walls because of a phenomenon known as thermophoresis which may result in loss of up to 20% of the product particles.", "The cooler/diluter (24) consists of a porous tube (28) jacketed by a solid wall tube (29).", "Cooling gas (27) is supplied to the jacket and flows inwards from the porous tube walls.", "After mixing of the hot gas flow from the furnace and the cooling gas the total temperature is reduced to a sufficiently low value typically below 200° C. This "transpiration flow"", "of the gas keeps the product particles away from the walls.", "The product particles (30) are collected in a fabric filter (not shown) in the form of a cake deposited on bags of cartridges made out of a filter media such as Goretex® coated Teflon® felt.", "The powder product is released from bags into a hopper by a reverse flow caused by a pulsed gas jet or shaking.", "The particle collector is a conventional structure.", "Other conventional devices such a cyclone separator or an electrostatic precipitator may be used alone or in addition to the filter.", "The carrier gas and other reaction products exiting the filter are scrubbed in section (9) to remove contaminants such as oxides of nitrogen, nitric acid vapors and/or hydrogen chloride.", "The carrier gases and acids can be purified and recycled.", "The product particle produced by the present invention is not hollow as hollow particles are generally considered undesirable for most uses.", "The particles of this invention are fully densified, that is, dense throughout their composition.", "The following examples will serve to illustrate more detailed aspects of the invention.", "EXAMPLE 1 A stable solution of silver and palladium nitrates containing 9% metal at a silver to palladium ratio of 30:70 was prepared by addition of excess nitric acid so as to yield 36% free acid.", "The solution was atomized by an acoustic device operating at a frequency of 1.7 MHz.", "The acoustic device consists of a number of piezo electric transducers and circuits made by American Piezo Ceramic (APC) Company for humidification equipment.", "A carrier gas flow of 20 liters per minute was used.", "The residence time in the high temperature zone (6) was of the order of 1 second.", "Particles were produced with and without the use of the separator.", "To remove all droplets resulting in palladium particles over 2 micrometers, the cut size should be 1 micrometer, the solution droplet size to be removed is obtained by using p s =1.38 g/cc.", "and is equal to 4.6 μm.", "The gap width W is obtained by substituting d sc =4.2, U by Equation II, ρ s =1.38, and μ=1.8·10E-4 poise.", "W=2.59·10 -4 ·Q and for the 20 liters per minute flow W=0.33 mm.", "The mist exiting the separator was dried to obtain nitrate particles at a temperature of 150° C. and then flowed through the reactor tube maintained at 1400° C. The residence time was 2 seconds.", "The powder converted to metal and was collected in Teflon coated filter bags maintained at a temperature of 120° C. Powder sample was collected with and without the first stage of the selector.", "Particle size was determined using a Leeds and Northrupp Microtrac instrument.", "The sample with separator in place contained essentially no particles over 2 micrometers, while a sample without the separator contained several large particles as seen from FIGS. 5A and 5B, respectively.", "A micrograph of the particles is shown in FIG. 6. An X-ray diffraction spectrum of the powder is shown in FIG. 7 and indicates the particles are true alloys with excellent crystallinity.", "EXAMPLE 2 An illustration of the effect of controlled drying on powder properties was explored.", "Starting with a precursor mixed solution of Pd and Ag--nitrates to yield a product with 60% Pd and a 40% Ag content, a mist was generated in section (3) of FIG. 1. The mist passed through the large droplet separator (4) and through the dryer (5).", "The mist then was subjected to a maximum temperature of 1000° C. to complete product conversion which was then collected in the filter (8).", "In the first run represented by an electron micrograph of the particles as FIG. 8, the mist was not subjected to heat in the dryer section.", "As a result, the droplets entering the reactor were wet.", "In the second run represented by FIG. 9, the droplets were dried in heating section (5) so that the temperature of the mist entering the reactor was at 130° C., at which temperature the mist particles were completely dry.", "FIG. 8 shows the presence of smaller particles attached to the normally smooth particles, while only the normal particles are seen in FIG. 9. The presence of the smaller particles below 0.3 micrometers is undesirable in several applications as they degrade the electronic properties of the powder and show a tendency to oxidize at lower temperature.", "EXAMPLE 3 The following example illustrates the benefits of achieving higher particle concentration in the carrier gases.", "The agglomeration of particles results in hard aggregates if the temperature is high and the degree of aggregation is dependent on the self-diffusion coefficient of the product metal and the residence time.", "The degree of aerosol coagulation resulting in particle contacts is expressed as 1/n-1/n.", "sub.", "o =K·t or n.sub.", "o /n=1+K·t n.sub.", "o where n is the number concentration at time t in #/cc, n o is the initial number concentration #/cc, K is the Smoluchowski coagulation coefficient cc/s, and t is time in seconds.", "At a temperature of 1400° C. in the conversion zone, the value of the coagulation coefficient is of the order 10 -8 cc/s.", "If the initial concentration is of the order 10 8 #/cc, in one second the concentration will drop by a factor of 2 resulting in a size increase of about 20%, and in 10 seconds the concentration will drop by a factor of 11, resulting in a size increase by a factor of 2.3.", "Thus, a residence time of 1 second in the high temperature zone will allow higher concentration than possible for a residence time of 10 seconds.", "This results in significant savings in the energy costs.", "Our calculations show that reduction of residence time from 10 seconds utilized by Kodas et al.", "to 1 second in accordance with the invention will allow a ten-fold permissible increase in droplet number concentration to maintain the same level of agglomeration.", "A wide range of metallic powder can be prepared in accordance with this invention.", "The above examples shows specific materials used in the process of this invention.", "Other noble metals and base metals can be used with appropriate conditions.", "Examples are Pt, Ag, Cu, Ni, Co, Ni, Ru and Ta, as well as alloys.", "Particle size of a few microns or less is a largely known and proven requirement for multi-layer capacitor electrode materials.", "Larger particles are known to cause shorting of the parts by penetrating too far into, or through, the dielectric material layer.", "As far as the lower end of the size range is concerned, there is no lower limit to size, but smaller particles are known to be more reactive and sinter at lower temperatures, so it is common practice to limit the number of very small particles in order to avoid such problems.", "Further variations and modifications will become apparent to those skilled in the art from the foregoing and are intended to be encompassed by the claims appended hereto." ]
FIELD OF THE INVENTION The invention relates to an apparatus and a method for the quantitative analysis of sleep disturbances or disorders, in particular for the stationary and ambulant detection, recording and analysis of sleep-related respiratory disturbances, cardiac rhythm disturbances, myoclonia, variations in blood pressure, depth of sleep parameters, movement parameters and disturbance or disorder parameters. BACKGROUND OF THE INVENTION Due to the increasing number of people suffering from sleep disorders and the related overburdening of sleep laboratories dealing with these disorders, the examination and measurement of disturbances by means of mobile apparatuses has been shifted from the stationary sector to the ambulant sector. The patients are told how to deal with the sensors connected with these apparatuses and, after the measuring time, return the mobile recording apparatus to the doctor attending them; the doctor then analyzes the recorded measuring signals to subsequently make a diagnosis. This ambulant method is very inexpensive due to the high time requirements related with a measurement and, furthermore, the results are not influenced by performing the measurements in a surrounding which is strange for the patient. Such a mobile recorder is described in EP-A-0 356 603. This recorder allows the recording of measuring signals by means of eight channels, their storage and subsequent analysis in a computer. In this connection, it is possible to program the recorder in different ways in order to reduce the number of measured data by a preselection and to limit the data to desired measuring data depending on the clinical picture or the purpose of the diagnosis. By this different programming, the measurement can be adapted to different frame conditions. The measurement of different parameters for the detection of sleep disturbances is discussed in DE-A-41 38 702. The apparatus disclosed therein comprises sensors for detecting the heart potential, the respiratory and snoring sounds, the degree of oxygen saturation of the blood and the patient's body position. An analysis of the measured results allows the diagnosis of apnea. However, this analyzing apparatus is limited to only one application purpose, namely the detection of sleep disturbances (apnea) and, with the mentioned sensors, comprises analyzing instruments designed for this very purpose only. In particular, although sleep-related respiratory disturbances can be detected, the "side effects" related therewith, such as cardiac rhythm disturbances, cannot be detected. With respect to the prior art, reference is also made to DE 92 04 190 U1, DE 32 48 222 A1, DE 39 21 784 A1, U.S. Pat. No. 3,734,086, DE 92 00 249 U1 and Kurz, Roland: "Medizinische MeBtechnik und Biosignalverarbeitung in der kardiologischen Diagnostik" [Medical Measuring Technique and Biosignal Processing in Cardiological Diagnostics], M.-G.-Schmitz-Verlag GieBen 1984, pages 122-129, ISBN 3-922 272-23-1. BRIEF SUMMARY OF THE INVENTION It is the object of the invention to provide an apparatus and a method for the quantitative analysis of sleep disturbances by means of which disturbances occurring during sleep can most exactly and completely be detected, so that in addition to the analysis of these disturbances also disturbances of other body functions resulting therefrom can be detected. In particular, the apparatus and method is meant for detecting sleep disturbances based on cardiac rhythm disturbances (so-called "apnea-associated cardiac rhythm disturbances"). These objects are achieved with the features of the claims. In achieving these objects, the invention is based on the following basic idea. For a quick and exact analysis of sleep disturbances and disturbances related therewith, it is very important which body signals are recorded and how many parameters are necessary for indicating the cause of the disturbances by a correlation or comparison of these signals. For this reason, in the present invention it is possible to measure the heart potential, the oxygen saturation of the blood, the body position, movements of the body, respiratory sounds, the positive pressure respiration, the respiratory flow, the respiratory activity and other electro-physiological measuring values by means of different sensors and to thus provide comprehensive data material for the analysis. The measured signals are supplied by the sensors to a mobile recorder, intermediately stored therein and, after the measuring cycle, read out and processed by a computer, e.g. a personal computer. For this, the recorder comprises a storage card as an external storage. This storage card is used for storing the signals and is, moreover, programmed for the subsequent application prior to the measurement. In this way, a purposeful selection of specific sensors is possible by selecting a respective program. This division into two hardware components allows any stationary or mobile use of the apparatus. For the analysis of the measured data, these data may on the one hand be directly displayed on the monitor of the PC in an unamended form, wherein of course desired time domains may be selected, and, on the other hand, these data are, however, also used as a basis for an evaluation by means of which further parameters may be detected. For example, the heart potential signal is supplied to a heart rate analyzer which thus determines the changes in the heart rate directly or by means of a correlation with other measured values or histograms. Moreover, the measured values are edited by means of suitable computational operations so that they can, e.g., be displayed in the form of tables or histograms. In particular, the oxygen saturation of the blood, the patient's position changes, snoring activities and respiratory disturbances can in this way be displayed clearly and expressively. In therapy control, the positive respiration pressure of the positive pressure respirators is also registered. By a correlation or comparison of these data, e.g. sleep disturbances, respiratory disturbances, cardiac rhythm disturbances can be detected. In particular, it is advantageous that cardiac rhythm disturbances caused by sleep disturbances can be detected. This very kind of cardiac rhythm disturbances cannot be treated sufficiently by common methods such as anti-arrhythmic drugs or cardiac pace-makers. However, if a causal relation between these cardiac rhythm disturbances and the sleep disturbances can be detected, the cardiac rhythm disturbances can causally be eliminated by treating the sleep disturbances. In order to increase the efficiency of the analysis, disturbance signals of the environment and a decrease in the distribution voltage are taken into account for the evaluation. Monitoring the distribution voltage prevents a data loss since in case of a voltage drop the data detected up to that time are stored and can be used for the evaluation. The disturbance signals inputted via the sensor cables are filtered in different frequency ranges and can then be compared with the useful signals in order to thus locate those signal parts in the useful signals which were caused by the disturbance fields. Thus, these disturbance parts do not have to be taken into consideration during the analysis. Moreover, alarm generators are provided which alarm when a predetermined threshold value of the oxygen saturation of the blood or the heart rate is reached and thus allow the use of the apparatus also for high-risk patients. The recorder is advantageously provided with a real-time clock so that, on the one hand, a real-time display of the signals and, on the other hand, the use during a very special time period is possible. For this, the recorder is changed into a "sleep" mode and the measurements do not start before a desired time. This has particular advantages when the recorder is preset in an institute and then sent to the patient. As a special embodiment, the present invention also allows the recordation of EEG signals and blood pressure values of other mobile apparatuses. Thus, by the EEG signal also the depth of sleep can be detected. A further advantage of the apparatus according to the invention can be seen in that by a comparison of the heart potential signal and the signal of the measurement of the oxygen saturation of the blood, the pulse rate or its change can be detected. Since it correlates with the variations in the blood pressure, an additional blood pressure measurement is no longer necessary for detecting these variations. The apparatus according to the invention now allows a method for the quantitative analysis of sleep disturbances in which a programmed recorder records and stores signals recorded by measuring sensors. These data are subsequently (in the case of a mobile use) or simultaneously (stationary) transferred to a computer and processed therein. The measured and processed data are then displayed graphically. BRIEF DESCRIPTION OF THE DRAWINGS In the following, the invention is explained in more detail in connection with the drawings in which FIGS. 1a) and b) show graphical illustrations of a selection of the detected values as a function of time in two different time intervals, FIGS. 2 to 6 show illustrations of a selection of analysis results in the form of tables (FIGS. 2b, 3b, 3d, 4a, 4c) and diagrams (FIGS. 3a, 3c, 4b, 5, 6) with patient data (FIG. 2a), FIG. 7 shows a schematic illustration of the apparatus according to the invention, FIG. 8 shows the evaluation of a first heart rate signal, FIG. 9 shows the evaluation of a second heart rate signal, FIG. 10 the evaluation of a respiratory signal, FIG. 11 the evaluation of a first signal of the oxygen saturation of the blood from the pulse oximeter, and FIG. 12 the evaluation of a second signal of the oxygen saturation of the blood from the pulse oximeter. DETAILED DESCRIPTION OF THE INVENTION In the following, the sensors used and the measuring signals provided by them are first explained in more detail. A schematical illustration of the apparatus according to the present invention can be taken from FIG. 7. The patient's respiratory sounds and snoring sounds are recorded by an electret microphone 4 which must be positioned at the larynx. The frequency range of this microphone is between 50 and 1500 Hz. The analog signal curve provided by this microphone is rectified and filtered, then the enveloping curve is scanned and digitized by a frequency which can be preselected via a configuration menu. The respiratory flow (flow in FIG. 1) is simultaneously taken from the nose and mouth by means of a thermistor 5 or a thermoelement. For this, a sum signal is formed which, on the one hand, allows the determination of the respiratory frequency and, on the other hand, the detection of the respiratory amplitude. Thus, together with the sensors for thorax and abdomen, which will be described in the following, occurring apnei can be differentiated well. The thoracic respiratory movement is recorded by a piezoceramic sensor 6 contained in a distribution box 15 in which various measuring cables meet. The distribution box contains pre-amplifiers for the measuring sensors. For the abdominal respiratory movement a piezoceramic sensor 7 is used, too. For registering the movements of the extremities, at least one actography sensor 8 is provided. This sensor can, e.g., be positioned on the arm or leg and, if a second sensor is used which is connected to the first sensor via a Y-separating-filter, the movements of both the arms and/or legs can be detected simultaneously. By means of these actography sensors, periodic movements of the extremities can be detected, which can be allocated as compared to heart rate variations. Electrocardiography (ECG) is used for measuring the heart potential. For this, the three electrodes 9 are positioned on the standardized locations on the body. The analog heart potential is digitized and stored as an ECG signal. At the same time, the analog ECG signal is supplied to a peak value detector to allow the determination and storage of the heart rate based on the time intervals between the R-peaks. The oxygen saturation of the blood is measured by a pulse oximeter 10, the sensor of which is positioned on the patient's finger. Moreover, like in a nasal hyperbaric oxygen therapy, during the measuring period the positive pressure respiration can be detected directly on the mask by means of a pressure sensor 11. Together with a pre-amplifier electronic circuitry and a separate power supply, the pressure sensor is incorporated into a separate housing. The measuring range lies between -10 mbar and 30 mbar. Finally, the body position can be detected by a position sensor 12 consisting of, e.g., four mercury switches. This position sensor stably shows 5 positions: right, left, supine position, abdominal position, upright. This position sensor, too, can be integrated in the distribution box. The position sensor allows the determination of the actual time of the sleep position and the times of uneasy sleep; thus, different apnea phases can be detected depending on the body position, and also artifacts can be allocated well. A special advantage can be seen in that both the position sensor and the piezo sensor for the thoracic respiratory movement are integrated in the distribution box; thus, the number of measuring points on the patient's body is reduced. The following is a short description of a measuring process. Prior to the actual ambulant or stationary operation, the apparatus is programmed for the respective application via a flow chart on the storage card provided in the recorder 3. During the recording, all physiological signals are stored on this storage card. The recorder is programmed by reading-in a flow chart for an internal microprocessor from the storage card, which takes place immediately after inserting the storage card. The recorder has a real-time clock and can be programmed to start on a predetermined time point or date. After programming, the recorder changes into a power-saving "sleep mode" and is waked by the real-time clock at the programmed starting time and date and switched off again at a stopping time. Depending on the medical questions and the configuration necessary therefor (channel number, scanning rates, starting time, stopping time, patient data, etc.), the flow charts are written on the storage card by a computer 1. Depending on the use of the storage cards (PCMCIA-ATA-standard), storage capacities between 1.8 Mbytes and 170 Mbytes can be used. Thus, the different storage capacities of the storage cards allow a configuration of the physiological signals with different scanning rates and with different recording times via the flow charts. After reading-in in the computer, the physiological data stored on the storage card are stored without any falsification as rough data and can at any time be newly analyzed and displayed. In the stationary real-time operation, the recorder is directly connected with the computer via a serial interface 2 which is used for the data transfer to the PC during recording. In order to reduce the possibility of a faulty diagnosis caused by malfunction or a patient's inappropriate use in the ambulant operation, the doctor can afterwards control the correct course of the recording. For this, e.g., the supply voltage is recorded, wherein the recording is stopped when the supply voltage falls below a predetermined value. The data recorded up to that time, however, can all be evaluated. After the application, the functionality of the recorder and the sensors is controlled by the real-time display on the computer. If no computer is available, application control takes place by means of LED-lamps provided on the front surface of the recorder. After reading-in the flow chart, a test mode lasting five minutes is started, in which the LED-lamps light upon application of a respectively allocated sensor. This test program can be re-started when a marker key 13 is pressed. The marker key is provided for enabling the patient to mark specific events, such as e.g. waking up in the night. FIGS. 2 to 6 exemplarily show the evaluation of a measuring cycle, wherein the data are illustrated in different ways. Signals, which are expressive already in the rough version, are illustrated for a desired time period as a function of time. The data of the measurement of the oxygen content of the blood, the position sensors, the electret microphone and the piezoelectric sensors for detecting the respiratory activity are evaluated in accordance with statistical methods and illustrated in the form of tables and histograms. The heart rate distribution (FIG. 4) is also illustrated as a graph. Moreover, as shown in FIG. 1, a mere time dependency of the data can be illustrated. In particular, the temporal courses of the measured signals can be illustrated in any desired combination, and a combined display of respiratory and cardiological parameters allows an allocation of specific cardiac rhythm disturbances to the occurring sleep disturbances. These cardiac rhythm disturbances are best observed in the temporal illustration of the heart rate and qualitatively and quantitatively detected during evaluation. The heart rate variations are detected automatically, and a heart rate index is calculated therefrom. To distinguish cyclical heart rate variations induced by sleep apnea from those variations induced by myoclonus, the heart rate signal is compared with the signal of the actography sensor. The respiratory events, i.e. the sleep-related respiratory disturbances, are also quantitatively analyzed during evaluation and described by different indices calculated therefrom. These are also illustrated in the form of a table, as evident from the bottom of FIG. 2. By the application of special evaluation algorithms which will be described later, the present invention allows a differentiation between hypopnea and obstructive, central or mixed apnea. Moreover, in the automatic analysis of apnea and hypopnea, the recorded pressure variations in the nasal hyperbaric oxygen therapy are used instead of the respiratory flow signal, thus permitting an exact therapy control. By means of the comprehensive data material made available for the doctor by the present invention, the doctor is in a position to make an exact diagnosis with respect to sleep disturbances, respiratory disturbances and cardiac rhythm disturbances. The attended patient can thus be treated purposefully. As an example, the following correlations, which can be performed automatically within the scope of the invention, are possible: 1. A correlation between snoring sounds and oxygen reduction indicates an obstructive apnea. 2. A correlation between rhythmic leg movements (PLMs, myoklonus) and heart rate, without snoring and without oxygen desaturations, indicates an influence of leg movements on the cardiovascular system with arousal effect. 3. An arrhythmia without a correlation to another signal indicates an absolute arrhythmia. 4. An arrhythmia synchronous to the respiratory signals indicates sinus arrhythmia and apnea-associated arrhythmia. 5. A compensatory arrhythmia without correlation to other signals indicates ventricular extrasystoles. 6. A regular oxygen desaturation with synchronous interruption of flow, as well as movements of the thorax and abdomen indicate a central apnea. 7. Long-lasting oxygen desaturations with a possibly unspecified reduction of the respiratory parameters and a possibly slow change of the heart rate indicate an obstructive lung decease. 8. A strong apnea with strong synchronous oxygen desaturations and slight but synchronous heart rate variations indicates an autonomic neuropathy (e.g. in the case of an advanced diabetes). 9. A decreasing heart rate after the change from the upright into the horizontal position indicates falling asleep. In case of a simultaneous apnea or PLM, the time point at which the patient falls asleep can be detected with only a slight error tolerance. 10. Irregular changes occurring approximately each one and a half hours simultaneously in all signals and lasting for approximately 20 to 40 minutes, indicate REM sleep (dream sleep). 11. Regular snoring without oxygen desaturation but with cyclical heart rate increases indicates an UARS (Upper Airways Resistance Syndrome). 12. The difference between the absolute values of thoracic and abdominal movements is detected as the obstruction rate and illustrated in a diagram (e.g. in an additional channel). In the following, the evaluation algorithms referring to the heart rate analysis, the algorithms for the detection of apnea and hypopnea and the algorithm for the detection of oxygen desaturations are discussed. The physiological data are, on the one hand, evaluated visually by means of the rough data and, on the other hand, by means of the automatic evaluation programs on the computer. The automatic heart rate analysis Algorithm for the detection of heart rate variations (apnea-associated sinus arrhythmia) In this case, the R peak distance, the so-called tachogram, is used. The algorithm works off the table with the heart rate values as follows. The respective heart rate is indicated by h i , Δ h i indicates the differences from h i . Algorithm for the detection of heart rate increases n=maximum duration for the increase for i=1, . . . , n Δh i =h i -h i-1 Taking up Δ h i into the integration buffer. The integration buffer is an n-dimensional vector, which is initialized with zeros. ##EQU1## Calculating the sum by means of the individual vector elements ##EQU2## Case distinction Integral<0: The heart rate curve has descended. The integration buffer is initialized with zeros. Integration buffer [i]=0; i=1, . . . , n 0<integral<threshold: The heart rate curve has ascended, but not enough. Integral>threshold: The heart rate curve has ascended by at least the threshold value. The first citerion for an event is fulfilled. Search for the maximum From the starting point of the ascent, the maximum is searched for. This is achieved by comparing the heart rate values. for n=1, . . . , end of table read-in value>present maximum: value>maximum new value is read in read-in value<present maximum: ═value maximum═≦discontinuation threshold: The heart rate curve has descended again, but not so much that the ascent could be regarded as finished. The search for the maximum is continued. ═value maximum═>discontinuation threshold: The heart rate curve has descended again, namely by at least the value of the discontinuation threshold. Thus, the maximum has been detected. Starting out from the detected maximum, the starting point and the finishing point of the heart rate variation are now searched for. Search for the starting point of the ascent Going backwards in time and starting out from the detected maximum, the starting point of the ascent, the 1st minimum, is now searched for. The search takes place analogously to the search for the maximum. The table values are gone through backwards until the end of the preceding ascent is reached, at the most, however, up to the "finishing point of the search interval for the first minimum", a value which can be preselected by the user. for last minimum, . . . , maximum: read-in value<present 1st minimum: value=1st minimum new value is read in read-in value>present 1st maximum: ═value--1st minimum═≦discontinuation threshold: The heart rate curve has ascended again, but not so much that the starting point of the ascent could be regarded as having been reached. The search for the starting point is continued. ═value--1st minimum═>discontinuation threshold: The heart-rate curve has ascended again, namely by at least the value of the discontinuation threshold. Thus, the starting point of the ascent has been detected. Now, the finishing point of the ascent is determined in the next step. Search for the finishing point of the heart rate increase Going forward in time and starting out from the detected maximum, the finishing point of the ascent, the 2nd minimum, is now searched for. The search takes place analogously to the search for the 1st minimum. The table values are gone through forward until a minimum is detected, at the most, however, up to the "finishing point of the search interval for the second minimum", a value which can be preselected by the user. for i=1, . . . , n: read-in value<present 2nd minimum: value=2nd minimum new value is read in read-in value>present 2nd minimum: ═value--2nd minimum═≦discontinuation threshold: The heart rate curve has ascended again, but not so much that the finishing point of the ascend could be regarded as having been reached. The search for the finishing point is continued. ═value--2nd minimum═>discontinuation threshold: The heart rate curve has descended again, namely by at least the value of the discontinuation threshold. Thus, the 2nd minimum has been detected. Analogously to the SaO 2 analysis, also in this case the individual parameters play an important role. Since the heart rate signal is much more complex than the SaO 2 signal, specific phenomena occur more intensely. FIG. 8 exemplarily illustrates the heart rate analysis. The analysis parameters of the heart rate analysis In this case, too, the individual preselectable parameters are once again explained in detail. Minimum heart rate increase ε[1, 30] This value determines how much the heart rate curve has to ascend in order to start the search for the maximum. In the algorithm, this value is the integration threshold. Maximum time interval for the Hf increase ε[1, 250] This value limits the time period in which the descent of the Hf curve has to take place. In the algorithm, it determines the dimension of the integration buffer. Discontinuation threshold for min-max-search ε[1, 10] The discontinuation threshold is the discontinuation criterion for a minimum or maximum search when the Hf curve is changed for this amount. Minimum and maximum event time ε[1, 250] In the long run, these two parameters are decisive for whether or not a detected heart rate increase is taken up in the event list as an event. In order to be taken up as an event, the following must apply for the duration of the increase: min. event time<(t 2nd min≡t 1st min)<max. event time Search interval for the maximum ε[1, 30] It limits the search environment for the search for the maximum thereby starting out from a present and thus temporary maximum. Search interval for the first minimum ε[1, 30] This search interval limits the search environment for the search for the starting point of the heart rate increase. This interval is a second discontinuation criterion in addition to the discontinuation threshold. It prevents the algorithm from running to death when the heart rate meets a plateau (FIG. 8). Search interval for the second minimum ε[1, 30] This search interval limits the search environment for the search for the finishing point of the increase. This interval is a second discontinuation criterion in addition to the discontinuation threshold. It prevents the algorithm from running to death when the heart rate curve meets a plateau (FIG. 9). The basic parameter selection is: ______________________________________minimum heart rate increase: 8discontinuation threshold 8for minimum-maximum-search:search interval for the maximum: 30 ssearch interval for the 1st minimum: 10 ssearch interval for the 2nd minimum: 10 sminimum event time: 5 smaximum event time: 150 s______________________________________ The respiratory channels Algorithm for the detection of apnea and hypopnea The algorithm takes place in three steps: filtering the present dates calculating the limiting values performing the analysis on the basis of the edited data It is necessary to filter the data since the signal of the respiratory channels is complicated and susceptible to disturbances. Filtering takes place floatingly or smoothly, for one second each; this corresponds to 250 sampling values. Filtering the data: The sampled values of the respective respiratory channel are represented by f i . ##EQU3## Taking up A fi into the difference buffer. The difference buffer is an 250-dimensional vector which is initialized with zeros. ##EQU4## Calculating the sums for the integral buffer ##EQU5## These values are used for the following calculations. An apnea or hypopnea is characterized in that the respiratory curve descends by a certain percentage as compared to the previous respiration. Since respiration is always a sinusoidal curve whose amplitude varies even in the case of healthy persons, the average value has to be calculated by means of the previous breaths in order to detect a breath decrease. This is done by means of the following algorithm: Algorithm for the detection of apnea/hypopnea limits The average value is calculated by means of the minima and maxima of the last 10 breaths. Detection of the maximum: sum i >0: if sum i+l >max>0, i.e. the respiratory curve is still ascending, max=sum i+1 if sum i+1 <0, i.e. the curve has already exceeded the maximum, the last calculated maximum is valid. Detection of the minimum: sum i <0: if sum i+1 <min<0, i.e. the respiratory curve is still descending, min=sum i+l if sum i+1 >0, i.e. the curve has already exceeded the minimum, the last calculated minimum is valid. By means of the amounts of the calculated minima and maxima, the average value is calculated: ##EQU6## The apnea/hypopnea limits are then calculated from ##EQU7## wherein the event threshold can be selected in percentages. All auxiliaries necessary for the analysis are now ready. Algorithm for the detection of apnea and hypopnea for i=1, . . . , 250 If ═sum i ═<limit set counter=0 and start to count. If ═sum i ═>limit check how far the counter has run. If minimum event time<counter<maximum event time an apnea or hypopnea has been detected. This analysis is performed on all respiratory channels. Obstructive and central apnea are differentiated on the basis of the thoracic and abdominal activity. If the respiratory activity decreases on the mouth and nose, the program checks whether, in correlation thereto, the thoracic and abdominal activity decreases as well. If this is the case, a central apnea is concerned. FIG. 10 illustrates the analysis for the detection of apnea. The analysis parameter of the apnea analysis The parameters in the apnea analysis are determined by the medical diagnosis. The following parameters can be selected: Apnea threshold In order to diagnose an apnea, the respiratory curve must descend by at least 80% with respect to the average value of the last ten breaths. In the algorithm, this value corresponds to the event threshold. Minimum apnea time This value limits the time interval in which the respiratory curve must lie below the apnea threshold. The minimum apnea time must last at least 10 seconds. Hypopnea threshold In order to diagnose a hypopnea, the respiratory curve must descend by at least 50% with respect to the average value of the last 10 breaths. In the algorithm, this value corresponds to the event threshold. Minimum hypopnea time This value limits the time interval in which the respiratory curve must lie below the hypopnea threshold. The minimum hypopnea time must last at least 10 seconds. Central apnea threshold In the case of a central apnea, the amplitude of the thoracic and abdominal signals must descend by at least 80% with respect to the average value of the last 10 breaths. Minimum central time This value limits the time interval in which the thoracic and abdominal curves must lie below the central apnea threshold. The minimum central apnea time must last at least 5 seconds. Maximum duration This value limits the maximum duration of a significant amplitude reduction for an event. Oxygen saturation channel Algorithm for the detection of desaturations The aim of the algorithm is the detection of oxygen desaturations. Since the oxygen saturation is sampled very high, a data reduction is necessary for a quick analysis. For this data reduction a table is made which contains the average value for a second. This does not mean a great information loss since during a second the oxygen saturation of the blood changes little as compared to the heart rate. The algorithm then searches this table for significant events. In this case, S i means the respective SaO 2 value from the table, and Δ S i means the difference from S i . Algorithm for the detection of oxygen desaturations n=maximum duration for the descent for i=1, . . . , n ΔS i =S i -S i-1 Taking up the ΔS i into the integration buffer. The integration buffer is an n-dimensional vector which is initialized with zeros. ##EQU8## Calculating the sum by means of the individual vector elements ##EQU9## Case distinction Integral>0: The SaO 2 curve has ascended, i.e. no desaturation is indicated. The integration buffer is initialized with zeros. Integration buffer [i]=0; i=1, . . . , n Threshold>integral>0: The SaO 2 curve has descended but not so much that a desaturation could be concerned. Integral<threshold: The SaO 2 curve has descended by at least the threshold value. The first criterion for a desaturation is fulfilled. Search for the minimum Starting out from the descent, it is now searched for the minimum. This is achieved by comparing the SaO 2 values. for n=1, . . . , end of table read-in value<present minimum: value=minimum new value is read in read-in value>present minimum: ═value minimum═≦discontinuation threshold: The SaO 2 curve has ascended again, but not so much that the desaturation could be regarded as finished. The search for the minimum is continued. ═value minimum═>discontinuation threshold: The SaO 2 curve has ascended again, namely by at least the value of the discontinuation threshold. Thus, the minimum has been detected. Starting out from this detected minimum, the starting point and the finishing point of the desaturation are now searched for. Search for the starting point of the desaturation Going backwards in time and starting out from the detected minimum, the starting point of the desaturation, the 1st maximum, is now searched for. The search takes place analogously to the search for the minimum. The table values are gone through backwards until the end of the preceding desaturation is reached, at the most, however, up to the "finishing point of the search interval for the first maximum", a value which can be preselected by the user. for last maximum, . . . ,minimum: read-in value>present 1st maximum: value=1st maximum new value is read in read-in value<present 1st maximum: ═value--1st maximum═<discontinuation threshold: The SaO 2 curve has descended again, but not so much that the starting point of the desaturation could be regarded as having been reached. The search for the starting point is continued. ═value--1st maximum═>discontinuation threshold: The SaO 2 curve has descended again, namely by at least the value of the discontinuation threshold. Thus, the 1st maximum has been detected since the previous desaturation has now been reached. In the next step, the finishing point of the desaturation is detected. Search for the finishing point of the desaturation Going forward in time and starting out from the detected minimum, the finishing point of the desaturation, i.e. the 2nd maximum, is now searched for. The search takes place analogously to the search for the 1st maximum. The table values are gone through forwards until a maximum is detected, at the most, however, up to the "finishing point of the search interval for the second maximum", a value which can be preselected by the user. for i=1, . . . n: read-in value>present 2nd maximum: value=2nd maximum New value is read in. read-in value<present 2nd maximum: ═value--2nd maximum═≦discontinuation threshold: The SaO 2 curve has descended again, but not so much that the finishing point of the desaturation could be regarded as having been reached. The search for the finishing point is continued. ═value--2nd maximum═>discontinuation threshold: The SaO 2 curve has descended again, namely by at least the value of the discontinuation threshold. Thus, the 2nd maximum has been detected since the following desaturation has been reached. This was the description of the basic algorithm. The appropriate selection of the analysis parameters plays an important role for the effective functioning of the algorithm. The SaO 2 analysis is illustrated in FIG. 11. The analysis parameters of the SaO 2 analysis As already mentioned, the effectivity of the algorithm depends on the selection of the appropriate parameters. All parameters can be selected freely. In the following, they should again be explained in more detail. Minimum SaO 2 descent ε[-10, -1] This value determines by how many percentage points the oxygen saturation curve must descend in order to initiate the search for the minimum. In the algorithm, this value is the integration threshold. Minimum time interval for the SaO 2 descent ε[1, 250] This value limits the time period in which the descent of the SaO 2 curve must take place. In the algorithm, it indicates the dimension of the integration buffer. Discontinuation threshold for min-max-search ε[1, 10] The discontinuation threshold is the discontinuation criterion for a minimum or maximum search when the SaO 2 curve is changed for this amount. Minimum and maximum event time-periods ε[1, 250] In the long run, these two parameters are decisive for whether or not a detected desaturation is taken up in the event list as an event. In order to be taken up as an event, the following must apply for the time period of the increase: min. event time<(t 2nd max -t 1st max)<max. event time Search interval for the minimum ε[1, 30] It limits the search environment for the search for the minimum thereby starting out from a present and thus temporary minimum. Search interval for the first maximum ε[1, 30] This search interval limits the search environment for the search for the starting point of the oxygen desaturation. This interval is a second discontinuation criterion in addition to the discontinuation threshold. It prevents the algorithm from running to death when the oxygen saturation meets a plateau. Search interval for the second maximum ε[1, 30] This search interval limits the search environment for the search for the finishing point of the oxygen desaturation. This interval is a second discontinuation criterion in addition to the discontinuation threshold. It prevents the algorithm from running to death when the oxygen saturation meets a plateau (FIG. 12). The basic parameter selection is: ______________________________________minimum SaO.sub.2 descent: -4%discontinuation threshold 2%for minimum-maximum-search:search interval for the minimum: 30 ssearch interval for the 1st maximum: 30 ssearch interval for the 2nd maximum: 30 sminimum event time: 5 smaximum event time: 150 s______________________________________
The invention relates to an apparatus and a method for the stationary and ambulant detection, recording and quantitative analysis of sleep disorders, sleep-related respiratory disturbances, cardiac rhythm disturbances, myoclonia, variations in blood pressure, depth of sleep parameters, movement parameters and disorder parameters for the quality control of diagnoses. According to the invention, various sensors detect a patient's body functions which are stored in a recorder. The stored data are then transferred to a computer where they are analyzed and evaluated.
Briefly outline the background technology and the problem the invention aims to solve.
[ "FIELD OF THE INVENTION The invention relates to an apparatus and a method for the quantitative analysis of sleep disturbances or disorders, in particular for the stationary and ambulant detection, recording and analysis of sleep-related respiratory disturbances, cardiac rhythm disturbances, myoclonia, variations in blood pressure, depth of sleep parameters, movement parameters and disturbance or disorder parameters.", "BACKGROUND OF THE INVENTION Due to the increasing number of people suffering from sleep disorders and the related overburdening of sleep laboratories dealing with these disorders, the examination and measurement of disturbances by means of mobile apparatuses has been shifted from the stationary sector to the ambulant sector.", "The patients are told how to deal with the sensors connected with these apparatuses and, after the measuring time, return the mobile recording apparatus to the doctor attending them;", "the doctor then analyzes the recorded measuring signals to subsequently make a diagnosis.", "This ambulant method is very inexpensive due to the high time requirements related with a measurement and, furthermore, the results are not influenced by performing the measurements in a surrounding which is strange for the patient.", "Such a mobile recorder is described in EP-A-0 356 603.", "This recorder allows the recording of measuring signals by means of eight channels, their storage and subsequent analysis in a computer.", "In this connection, it is possible to program the recorder in different ways in order to reduce the number of measured data by a preselection and to limit the data to desired measuring data depending on the clinical picture or the purpose of the diagnosis.", "By this different programming, the measurement can be adapted to different frame conditions.", "The measurement of different parameters for the detection of sleep disturbances is discussed in DE-A-41 38 702.", "The apparatus disclosed therein comprises sensors for detecting the heart potential, the respiratory and snoring sounds, the degree of oxygen saturation of the blood and the patient's body position.", "An analysis of the measured results allows the diagnosis of apnea.", "However, this analyzing apparatus is limited to only one application purpose, namely the detection of sleep disturbances (apnea) and, with the mentioned sensors, comprises analyzing instruments designed for this very purpose only.", "In particular, although sleep-related respiratory disturbances can be detected, the "side effects"", "related therewith, such as cardiac rhythm disturbances, cannot be detected.", "With respect to the prior art, reference is also made to DE 92 04 190 U1, DE 32 48 222 A1, DE 39 21 784 A1, U.S. Pat. No. 3,734,086, DE 92 00 249 U1 and Kurz, Roland: "Medizinische MeBtechnik und Biosignalverarbeitung in der kardiologischen Diagnostik"", "[Medical Measuring Technique and Biosignal Processing in Cardiological Diagnostics], M.-G.", "-Schmitz-Verlag GieBen 1984, pages 122-129, ISBN 3-922 272-23-1.", "BRIEF SUMMARY OF THE INVENTION It is the object of the invention to provide an apparatus and a method for the quantitative analysis of sleep disturbances by means of which disturbances occurring during sleep can most exactly and completely be detected, so that in addition to the analysis of these disturbances also disturbances of other body functions resulting therefrom can be detected.", "In particular, the apparatus and method is meant for detecting sleep disturbances based on cardiac rhythm disturbances (so-called "apnea-associated cardiac rhythm disturbances").", "These objects are achieved with the features of the claims.", "In achieving these objects, the invention is based on the following basic idea.", "For a quick and exact analysis of sleep disturbances and disturbances related therewith, it is very important which body signals are recorded and how many parameters are necessary for indicating the cause of the disturbances by a correlation or comparison of these signals.", "For this reason, in the present invention it is possible to measure the heart potential, the oxygen saturation of the blood, the body position, movements of the body, respiratory sounds, the positive pressure respiration, the respiratory flow, the respiratory activity and other electro-physiological measuring values by means of different sensors and to thus provide comprehensive data material for the analysis.", "The measured signals are supplied by the sensors to a mobile recorder, intermediately stored therein and, after the measuring cycle, read out and processed by a computer, e.g. a personal computer.", "For this, the recorder comprises a storage card as an external storage.", "This storage card is used for storing the signals and is, moreover, programmed for the subsequent application prior to the measurement.", "In this way, a purposeful selection of specific sensors is possible by selecting a respective program.", "This division into two hardware components allows any stationary or mobile use of the apparatus.", "For the analysis of the measured data, these data may on the one hand be directly displayed on the monitor of the PC in an unamended form, wherein of course desired time domains may be selected, and, on the other hand, these data are, however, also used as a basis for an evaluation by means of which further parameters may be detected.", "For example, the heart potential signal is supplied to a heart rate analyzer which thus determines the changes in the heart rate directly or by means of a correlation with other measured values or histograms.", "Moreover, the measured values are edited by means of suitable computational operations so that they can, e.g., be displayed in the form of tables or histograms.", "In particular, the oxygen saturation of the blood, the patient's position changes, snoring activities and respiratory disturbances can in this way be displayed clearly and expressively.", "In therapy control, the positive respiration pressure of the positive pressure respirators is also registered.", "By a correlation or comparison of these data, e.g. sleep disturbances, respiratory disturbances, cardiac rhythm disturbances can be detected.", "In particular, it is advantageous that cardiac rhythm disturbances caused by sleep disturbances can be detected.", "This very kind of cardiac rhythm disturbances cannot be treated sufficiently by common methods such as anti-arrhythmic drugs or cardiac pace-makers.", "However, if a causal relation between these cardiac rhythm disturbances and the sleep disturbances can be detected, the cardiac rhythm disturbances can causally be eliminated by treating the sleep disturbances.", "In order to increase the efficiency of the analysis, disturbance signals of the environment and a decrease in the distribution voltage are taken into account for the evaluation.", "Monitoring the distribution voltage prevents a data loss since in case of a voltage drop the data detected up to that time are stored and can be used for the evaluation.", "The disturbance signals inputted via the sensor cables are filtered in different frequency ranges and can then be compared with the useful signals in order to thus locate those signal parts in the useful signals which were caused by the disturbance fields.", "Thus, these disturbance parts do not have to be taken into consideration during the analysis.", "Moreover, alarm generators are provided which alarm when a predetermined threshold value of the oxygen saturation of the blood or the heart rate is reached and thus allow the use of the apparatus also for high-risk patients.", "The recorder is advantageously provided with a real-time clock so that, on the one hand, a real-time display of the signals and, on the other hand, the use during a very special time period is possible.", "For this, the recorder is changed into a "sleep"", "mode and the measurements do not start before a desired time.", "This has particular advantages when the recorder is preset in an institute and then sent to the patient.", "As a special embodiment, the present invention also allows the recordation of EEG signals and blood pressure values of other mobile apparatuses.", "Thus, by the EEG signal also the depth of sleep can be detected.", "A further advantage of the apparatus according to the invention can be seen in that by a comparison of the heart potential signal and the signal of the measurement of the oxygen saturation of the blood, the pulse rate or its change can be detected.", "Since it correlates with the variations in the blood pressure, an additional blood pressure measurement is no longer necessary for detecting these variations.", "The apparatus according to the invention now allows a method for the quantitative analysis of sleep disturbances in which a programmed recorder records and stores signals recorded by measuring sensors.", "These data are subsequently (in the case of a mobile use) or simultaneously (stationary) transferred to a computer and processed therein.", "The measured and processed data are then displayed graphically.", "BRIEF DESCRIPTION OF THE DRAWINGS In the following, the invention is explained in more detail in connection with the drawings in which FIGS. 1a) and b) show graphical illustrations of a selection of the detected values as a function of time in two different time intervals, FIGS. 2 to 6 show illustrations of a selection of analysis results in the form of tables (FIGS.", "2b, 3b, 3d, 4a, 4c) and diagrams (FIGS.", "3a, 3c, 4b, 5, 6) with patient data (FIG.", "2a), FIG. 7 shows a schematic illustration of the apparatus according to the invention, FIG. 8 shows the evaluation of a first heart rate signal, FIG. 9 shows the evaluation of a second heart rate signal, FIG. 10 the evaluation of a respiratory signal, FIG. 11 the evaluation of a first signal of the oxygen saturation of the blood from the pulse oximeter, and FIG. 12 the evaluation of a second signal of the oxygen saturation of the blood from the pulse oximeter.", "DETAILED DESCRIPTION OF THE INVENTION In the following, the sensors used and the measuring signals provided by them are first explained in more detail.", "A schematical illustration of the apparatus according to the present invention can be taken from FIG. 7. The patient's respiratory sounds and snoring sounds are recorded by an electret microphone 4 which must be positioned at the larynx.", "The frequency range of this microphone is between 50 and 1500 Hz.", "The analog signal curve provided by this microphone is rectified and filtered, then the enveloping curve is scanned and digitized by a frequency which can be preselected via a configuration menu.", "The respiratory flow (flow in FIG. 1) is simultaneously taken from the nose and mouth by means of a thermistor 5 or a thermoelement.", "For this, a sum signal is formed which, on the one hand, allows the determination of the respiratory frequency and, on the other hand, the detection of the respiratory amplitude.", "Thus, together with the sensors for thorax and abdomen, which will be described in the following, occurring apnei can be differentiated well.", "The thoracic respiratory movement is recorded by a piezoceramic sensor 6 contained in a distribution box 15 in which various measuring cables meet.", "The distribution box contains pre-amplifiers for the measuring sensors.", "For the abdominal respiratory movement a piezoceramic sensor 7 is used, too.", "For registering the movements of the extremities, at least one actography sensor 8 is provided.", "This sensor can, e.g., be positioned on the arm or leg and, if a second sensor is used which is connected to the first sensor via a Y-separating-filter, the movements of both the arms and/or legs can be detected simultaneously.", "By means of these actography sensors, periodic movements of the extremities can be detected, which can be allocated as compared to heart rate variations.", "Electrocardiography (ECG) is used for measuring the heart potential.", "For this, the three electrodes 9 are positioned on the standardized locations on the body.", "The analog heart potential is digitized and stored as an ECG signal.", "At the same time, the analog ECG signal is supplied to a peak value detector to allow the determination and storage of the heart rate based on the time intervals between the R-peaks.", "The oxygen saturation of the blood is measured by a pulse oximeter 10, the sensor of which is positioned on the patient's finger.", "Moreover, like in a nasal hyperbaric oxygen therapy, during the measuring period the positive pressure respiration can be detected directly on the mask by means of a pressure sensor 11.", "Together with a pre-amplifier electronic circuitry and a separate power supply, the pressure sensor is incorporated into a separate housing.", "The measuring range lies between -10 mbar and 30 mbar.", "Finally, the body position can be detected by a position sensor 12 consisting of, e.g., four mercury switches.", "This position sensor stably shows 5 positions: right, left, supine position, abdominal position, upright.", "This position sensor, too, can be integrated in the distribution box.", "The position sensor allows the determination of the actual time of the sleep position and the times of uneasy sleep;", "thus, different apnea phases can be detected depending on the body position, and also artifacts can be allocated well.", "A special advantage can be seen in that both the position sensor and the piezo sensor for the thoracic respiratory movement are integrated in the distribution box;", "thus, the number of measuring points on the patient's body is reduced.", "The following is a short description of a measuring process.", "Prior to the actual ambulant or stationary operation, the apparatus is programmed for the respective application via a flow chart on the storage card provided in the recorder 3.", "During the recording, all physiological signals are stored on this storage card.", "The recorder is programmed by reading-in a flow chart for an internal microprocessor from the storage card, which takes place immediately after inserting the storage card.", "The recorder has a real-time clock and can be programmed to start on a predetermined time point or date.", "After programming, the recorder changes into a power-saving "sleep mode"", "and is waked by the real-time clock at the programmed starting time and date and switched off again at a stopping time.", "Depending on the medical questions and the configuration necessary therefor (channel number, scanning rates, starting time, stopping time, patient data, etc.), the flow charts are written on the storage card by a computer 1.", "Depending on the use of the storage cards (PCMCIA-ATA-standard), storage capacities between 1.8 Mbytes and 170 Mbytes can be used.", "Thus, the different storage capacities of the storage cards allow a configuration of the physiological signals with different scanning rates and with different recording times via the flow charts.", "After reading-in in the computer, the physiological data stored on the storage card are stored without any falsification as rough data and can at any time be newly analyzed and displayed.", "In the stationary real-time operation, the recorder is directly connected with the computer via a serial interface 2 which is used for the data transfer to the PC during recording.", "In order to reduce the possibility of a faulty diagnosis caused by malfunction or a patient's inappropriate use in the ambulant operation, the doctor can afterwards control the correct course of the recording.", "For this, e.g., the supply voltage is recorded, wherein the recording is stopped when the supply voltage falls below a predetermined value.", "The data recorded up to that time, however, can all be evaluated.", "After the application, the functionality of the recorder and the sensors is controlled by the real-time display on the computer.", "If no computer is available, application control takes place by means of LED-lamps provided on the front surface of the recorder.", "After reading-in the flow chart, a test mode lasting five minutes is started, in which the LED-lamps light upon application of a respectively allocated sensor.", "This test program can be re-started when a marker key 13 is pressed.", "The marker key is provided for enabling the patient to mark specific events, such as e.g. waking up in the night.", "FIGS. 2 to 6 exemplarily show the evaluation of a measuring cycle, wherein the data are illustrated in different ways.", "Signals, which are expressive already in the rough version, are illustrated for a desired time period as a function of time.", "The data of the measurement of the oxygen content of the blood, the position sensors, the electret microphone and the piezoelectric sensors for detecting the respiratory activity are evaluated in accordance with statistical methods and illustrated in the form of tables and histograms.", "The heart rate distribution (FIG.", "4) is also illustrated as a graph.", "Moreover, as shown in FIG. 1, a mere time dependency of the data can be illustrated.", "In particular, the temporal courses of the measured signals can be illustrated in any desired combination, and a combined display of respiratory and cardiological parameters allows an allocation of specific cardiac rhythm disturbances to the occurring sleep disturbances.", "These cardiac rhythm disturbances are best observed in the temporal illustration of the heart rate and qualitatively and quantitatively detected during evaluation.", "The heart rate variations are detected automatically, and a heart rate index is calculated therefrom.", "To distinguish cyclical heart rate variations induced by sleep apnea from those variations induced by myoclonus, the heart rate signal is compared with the signal of the actography sensor.", "The respiratory events, i.e. the sleep-related respiratory disturbances, are also quantitatively analyzed during evaluation and described by different indices calculated therefrom.", "These are also illustrated in the form of a table, as evident from the bottom of FIG. 2. By the application of special evaluation algorithms which will be described later, the present invention allows a differentiation between hypopnea and obstructive, central or mixed apnea.", "Moreover, in the automatic analysis of apnea and hypopnea, the recorded pressure variations in the nasal hyperbaric oxygen therapy are used instead of the respiratory flow signal, thus permitting an exact therapy control.", "By means of the comprehensive data material made available for the doctor by the present invention, the doctor is in a position to make an exact diagnosis with respect to sleep disturbances, respiratory disturbances and cardiac rhythm disturbances.", "The attended patient can thus be treated purposefully.", "As an example, the following correlations, which can be performed automatically within the scope of the invention, are possible: 1.", "A correlation between snoring sounds and oxygen reduction indicates an obstructive apnea.", "A correlation between rhythmic leg movements (PLMs, myoklonus) and heart rate, without snoring and without oxygen desaturations, indicates an influence of leg movements on the cardiovascular system with arousal effect.", "An arrhythmia without a correlation to another signal indicates an absolute arrhythmia.", "An arrhythmia synchronous to the respiratory signals indicates sinus arrhythmia and apnea-associated arrhythmia.", "A compensatory arrhythmia without correlation to other signals indicates ventricular extrasystoles.", "A regular oxygen desaturation with synchronous interruption of flow, as well as movements of the thorax and abdomen indicate a central apnea.", "Long-lasting oxygen desaturations with a possibly unspecified reduction of the respiratory parameters and a possibly slow change of the heart rate indicate an obstructive lung decease.", "A strong apnea with strong synchronous oxygen desaturations and slight but synchronous heart rate variations indicates an autonomic neuropathy (e.g. in the case of an advanced diabetes).", "A decreasing heart rate after the change from the upright into the horizontal position indicates falling asleep.", "In case of a simultaneous apnea or PLM, the time point at which the patient falls asleep can be detected with only a slight error tolerance.", "10.", "Irregular changes occurring approximately each one and a half hours simultaneously in all signals and lasting for approximately 20 to 40 minutes, indicate REM sleep (dream sleep).", "11.", "Regular snoring without oxygen desaturation but with cyclical heart rate increases indicates an UARS (Upper Airways Resistance Syndrome).", "12.", "The difference between the absolute values of thoracic and abdominal movements is detected as the obstruction rate and illustrated in a diagram (e.g. in an additional channel).", "In the following, the evaluation algorithms referring to the heart rate analysis, the algorithms for the detection of apnea and hypopnea and the algorithm for the detection of oxygen desaturations are discussed.", "The physiological data are, on the one hand, evaluated visually by means of the rough data and, on the other hand, by means of the automatic evaluation programs on the computer.", "The automatic heart rate analysis Algorithm for the detection of heart rate variations (apnea-associated sinus arrhythmia) In this case, the R peak distance, the so-called tachogram, is used.", "The algorithm works off the table with the heart rate values as follows.", "The respective heart rate is indicated by h i , Δ h i indicates the differences from h i .", "Algorithm for the detection of heart rate increases n=maximum duration for the increase for i=1, .", ", n Δh i =h i -h i-1 Taking up Δ h i into the integration buffer.", "The integration buffer is an n-dimensional vector, which is initialized with zeros.", "##EQU1## Calculating the sum by means of the individual vector elements ##EQU2## Case distinction Integral<0: The heart rate curve has descended.", "The integration buffer is initialized with zeros.", "Integration buffer [i]=0;", "i=1, .", ", n 0<integral<threshold: The heart rate curve has ascended, but not enough.", "Integral>threshold: The heart rate curve has ascended by at least the threshold value.", "The first citerion for an event is fulfilled.", "Search for the maximum From the starting point of the ascent, the maximum is searched for.", "This is achieved by comparing the heart rate values.", "for n=1, .", ", end of table read-in value>present maximum: value>maximum new value is read in read-in value<present maximum: ═value maximum═≦discontinuation threshold: The heart rate curve has descended again, but not so much that the ascent could be regarded as finished.", "The search for the maximum is continued.", "═value maximum═>discontinuation threshold: The heart rate curve has descended again, namely by at least the value of the discontinuation threshold.", "Thus, the maximum has been detected.", "Starting out from the detected maximum, the starting point and the finishing point of the heart rate variation are now searched for.", "Search for the starting point of the ascent Going backwards in time and starting out from the detected maximum, the starting point of the ascent, the 1st minimum, is now searched for.", "The search takes place analogously to the search for the maximum.", "The table values are gone through backwards until the end of the preceding ascent is reached, at the most, however, up to the "finishing point of the search interval for the first minimum", a value which can be preselected by the user.", "for last minimum, .", ", maximum: read-in value<present 1st minimum: value=1st minimum new value is read in read-in value>present 1st maximum: ═value--1st minimum═≦discontinuation threshold: The heart rate curve has ascended again, but not so much that the starting point of the ascent could be regarded as having been reached.", "The search for the starting point is continued.", "═value--1st minimum═>discontinuation threshold: The heart-rate curve has ascended again, namely by at least the value of the discontinuation threshold.", "Thus, the starting point of the ascent has been detected.", "Now, the finishing point of the ascent is determined in the next step.", "Search for the finishing point of the heart rate increase Going forward in time and starting out from the detected maximum, the finishing point of the ascent, the 2nd minimum, is now searched for.", "The search takes place analogously to the search for the 1st minimum.", "The table values are gone through forward until a minimum is detected, at the most, however, up to the "finishing point of the search interval for the second minimum", a value which can be preselected by the user.", "for i=1, .", ", n: read-in value<present 2nd minimum: value=2nd minimum new value is read in read-in value>present 2nd minimum: ═value--2nd minimum═≦discontinuation threshold: The heart rate curve has ascended again, but not so much that the finishing point of the ascend could be regarded as having been reached.", "The search for the finishing point is continued.", "═value--2nd minimum═>discontinuation threshold: The heart rate curve has descended again, namely by at least the value of the discontinuation threshold.", "Thus, the 2nd minimum has been detected.", "Analogously to the SaO 2 analysis, also in this case the individual parameters play an important role.", "Since the heart rate signal is much more complex than the SaO 2 signal, specific phenomena occur more intensely.", "FIG. 8 exemplarily illustrates the heart rate analysis.", "The analysis parameters of the heart rate analysis In this case, too, the individual preselectable parameters are once again explained in detail.", "Minimum heart rate increase ε[1, 30] This value determines how much the heart rate curve has to ascend in order to start the search for the maximum.", "In the algorithm, this value is the integration threshold.", "Maximum time interval for the Hf increase ε[1, 250] This value limits the time period in which the descent of the Hf curve has to take place.", "In the algorithm, it determines the dimension of the integration buffer.", "Discontinuation threshold for min-max-search ε[1, 10] The discontinuation threshold is the discontinuation criterion for a minimum or maximum search when the Hf curve is changed for this amount.", "Minimum and maximum event time ε[1, 250] In the long run, these two parameters are decisive for whether or not a detected heart rate increase is taken up in the event list as an event.", "In order to be taken up as an event, the following must apply for the duration of the increase: min.", "event time<(t 2nd min≡t 1st min)<max.", "event time Search interval for the maximum ε[1, 30] It limits the search environment for the search for the maximum thereby starting out from a present and thus temporary maximum.", "Search interval for the first minimum ε[1, 30] This search interval limits the search environment for the search for the starting point of the heart rate increase.", "This interval is a second discontinuation criterion in addition to the discontinuation threshold.", "It prevents the algorithm from running to death when the heart rate meets a plateau (FIG.", "8).", "Search interval for the second minimum ε[1, 30] This search interval limits the search environment for the search for the finishing point of the increase.", "This interval is a second discontinuation criterion in addition to the discontinuation threshold.", "It prevents the algorithm from running to death when the heart rate curve meets a plateau (FIG.", "9).", "The basic parameter selection is: ______________________________________minimum heart rate increase: 8discontinuation threshold 8for minimum-maximum-search:search interval for the maximum: 30 ssearch interval for the 1st minimum: 10 ssearch interval for the 2nd minimum: 10 sminimum event time: 5 smaximum event time: 150 s______________________________________ The respiratory channels Algorithm for the detection of apnea and hypopnea The algorithm takes place in three steps: filtering the present dates calculating the limiting values performing the analysis on the basis of the edited data It is necessary to filter the data since the signal of the respiratory channels is complicated and susceptible to disturbances.", "Filtering takes place floatingly or smoothly, for one second each;", "this corresponds to 250 sampling values.", "Filtering the data: The sampled values of the respective respiratory channel are represented by f i .", "##EQU3## Taking up A fi into the difference buffer.", "The difference buffer is an 250-dimensional vector which is initialized with zeros.", "##EQU4## Calculating the sums for the integral buffer ##EQU5## These values are used for the following calculations.", "An apnea or hypopnea is characterized in that the respiratory curve descends by a certain percentage as compared to the previous respiration.", "Since respiration is always a sinusoidal curve whose amplitude varies even in the case of healthy persons, the average value has to be calculated by means of the previous breaths in order to detect a breath decrease.", "This is done by means of the following algorithm: Algorithm for the detection of apnea/hypopnea limits The average value is calculated by means of the minima and maxima of the last 10 breaths.", "Detection of the maximum: sum i >0: if sum i+l >max>0, i.e. the respiratory curve is still ascending, max=sum i+1 if sum i+1 <0, i.e. the curve has already exceeded the maximum, the last calculated maximum is valid.", "Detection of the minimum: sum i <0: if sum i+1 <min<0, i.e. the respiratory curve is still descending, min=sum i+l if sum i+1 >0, i.e. the curve has already exceeded the minimum, the last calculated minimum is valid.", "By means of the amounts of the calculated minima and maxima, the average value is calculated: ##EQU6## The apnea/hypopnea limits are then calculated from ##EQU7## wherein the event threshold can be selected in percentages.", "All auxiliaries necessary for the analysis are now ready.", "Algorithm for the detection of apnea and hypopnea for i=1, .", ", 250 If ═sum i ═<limit set counter=0 and start to count.", "If ═sum i ═>limit check how far the counter has run.", "If minimum event time<counter<maximum event time an apnea or hypopnea has been detected.", "This analysis is performed on all respiratory channels.", "Obstructive and central apnea are differentiated on the basis of the thoracic and abdominal activity.", "If the respiratory activity decreases on the mouth and nose, the program checks whether, in correlation thereto, the thoracic and abdominal activity decreases as well.", "If this is the case, a central apnea is concerned.", "FIG. 10 illustrates the analysis for the detection of apnea.", "The analysis parameter of the apnea analysis The parameters in the apnea analysis are determined by the medical diagnosis.", "The following parameters can be selected: Apnea threshold In order to diagnose an apnea, the respiratory curve must descend by at least 80% with respect to the average value of the last ten breaths.", "In the algorithm, this value corresponds to the event threshold.", "Minimum apnea time This value limits the time interval in which the respiratory curve must lie below the apnea threshold.", "The minimum apnea time must last at least 10 seconds.", "Hypopnea threshold In order to diagnose a hypopnea, the respiratory curve must descend by at least 50% with respect to the average value of the last 10 breaths.", "In the algorithm, this value corresponds to the event threshold.", "Minimum hypopnea time This value limits the time interval in which the respiratory curve must lie below the hypopnea threshold.", "The minimum hypopnea time must last at least 10 seconds.", "Central apnea threshold In the case of a central apnea, the amplitude of the thoracic and abdominal signals must descend by at least 80% with respect to the average value of the last 10 breaths.", "Minimum central time This value limits the time interval in which the thoracic and abdominal curves must lie below the central apnea threshold.", "The minimum central apnea time must last at least 5 seconds.", "Maximum duration This value limits the maximum duration of a significant amplitude reduction for an event.", "Oxygen saturation channel Algorithm for the detection of desaturations The aim of the algorithm is the detection of oxygen desaturations.", "Since the oxygen saturation is sampled very high, a data reduction is necessary for a quick analysis.", "For this data reduction a table is made which contains the average value for a second.", "This does not mean a great information loss since during a second the oxygen saturation of the blood changes little as compared to the heart rate.", "The algorithm then searches this table for significant events.", "In this case, S i means the respective SaO 2 value from the table, and Δ S i means the difference from S i .", "Algorithm for the detection of oxygen desaturations n=maximum duration for the descent for i=1, .", ", n ΔS i =S i -S i-1 Taking up the ΔS i into the integration buffer.", "The integration buffer is an n-dimensional vector which is initialized with zeros.", "##EQU8## Calculating the sum by means of the individual vector elements ##EQU9## Case distinction Integral>0: The SaO 2 curve has ascended, i.e. no desaturation is indicated.", "The integration buffer is initialized with zeros.", "Integration buffer [i]=0;", "i=1, .", ", n Threshold>integral>0: The SaO 2 curve has descended but not so much that a desaturation could be concerned.", "Integral<threshold: The SaO 2 curve has descended by at least the threshold value.", "The first criterion for a desaturation is fulfilled.", "Search for the minimum Starting out from the descent, it is now searched for the minimum.", "This is achieved by comparing the SaO 2 values.", "for n=1, .", ", end of table read-in value<present minimum: value=minimum new value is read in read-in value>present minimum: ═value minimum═≦discontinuation threshold: The SaO 2 curve has ascended again, but not so much that the desaturation could be regarded as finished.", "The search for the minimum is continued.", "═value minimum═>discontinuation threshold: The SaO 2 curve has ascended again, namely by at least the value of the discontinuation threshold.", "Thus, the minimum has been detected.", "Starting out from this detected minimum, the starting point and the finishing point of the desaturation are now searched for.", "Search for the starting point of the desaturation Going backwards in time and starting out from the detected minimum, the starting point of the desaturation, the 1st maximum, is now searched for.", "The search takes place analogously to the search for the minimum.", "The table values are gone through backwards until the end of the preceding desaturation is reached, at the most, however, up to the "finishing point of the search interval for the first maximum", a value which can be preselected by the user.", "for last maximum, .", ",minimum: read-in value>present 1st maximum: value=1st maximum new value is read in read-in value<present 1st maximum: ═value--1st maximum═<discontinuation threshold: The SaO 2 curve has descended again, but not so much that the starting point of the desaturation could be regarded as having been reached.", "The search for the starting point is continued.", "═value--1st maximum═>discontinuation threshold: The SaO 2 curve has descended again, namely by at least the value of the discontinuation threshold.", "Thus, the 1st maximum has been detected since the previous desaturation has now been reached.", "In the next step, the finishing point of the desaturation is detected.", "Search for the finishing point of the desaturation Going forward in time and starting out from the detected minimum, the finishing point of the desaturation, i.e. the 2nd maximum, is now searched for.", "The search takes place analogously to the search for the 1st maximum.", "The table values are gone through forwards until a maximum is detected, at the most, however, up to the "finishing point of the search interval for the second maximum", a value which can be preselected by the user.", "for i=1, .", "n: read-in value>present 2nd maximum: value=2nd maximum New value is read in.", "read-in value<present 2nd maximum: ═value--2nd maximum═≦discontinuation threshold: The SaO 2 curve has descended again, but not so much that the finishing point of the desaturation could be regarded as having been reached.", "The search for the finishing point is continued.", "═value--2nd maximum═>discontinuation threshold: The SaO 2 curve has descended again, namely by at least the value of the discontinuation threshold.", "Thus, the 2nd maximum has been detected since the following desaturation has been reached.", "This was the description of the basic algorithm.", "The appropriate selection of the analysis parameters plays an important role for the effective functioning of the algorithm.", "The SaO 2 analysis is illustrated in FIG. 11.", "The analysis parameters of the SaO 2 analysis As already mentioned, the effectivity of the algorithm depends on the selection of the appropriate parameters.", "All parameters can be selected freely.", "In the following, they should again be explained in more detail.", "Minimum SaO 2 descent ε[-10, -1] This value determines by how many percentage points the oxygen saturation curve must descend in order to initiate the search for the minimum.", "In the algorithm, this value is the integration threshold.", "Minimum time interval for the SaO 2 descent ε[1, 250] This value limits the time period in which the descent of the SaO 2 curve must take place.", "In the algorithm, it indicates the dimension of the integration buffer.", "Discontinuation threshold for min-max-search ε[1, 10] The discontinuation threshold is the discontinuation criterion for a minimum or maximum search when the SaO 2 curve is changed for this amount.", "Minimum and maximum event time-periods ε[1, 250] In the long run, these two parameters are decisive for whether or not a detected desaturation is taken up in the event list as an event.", "In order to be taken up as an event, the following must apply for the time period of the increase: min.", "event time<(t 2nd max -t 1st max)<max.", "event time Search interval for the minimum ε[1, 30] It limits the search environment for the search for the minimum thereby starting out from a present and thus temporary minimum.", "Search interval for the first maximum ε[1, 30] This search interval limits the search environment for the search for the starting point of the oxygen desaturation.", "This interval is a second discontinuation criterion in addition to the discontinuation threshold.", "It prevents the algorithm from running to death when the oxygen saturation meets a plateau.", "Search interval for the second maximum ε[1, 30] This search interval limits the search environment for the search for the finishing point of the oxygen desaturation.", "This interval is a second discontinuation criterion in addition to the discontinuation threshold.", "It prevents the algorithm from running to death when the oxygen saturation meets a plateau (FIG.", "12).", "The basic parameter selection is: ______________________________________minimum SaO.", "sub[.", "].2 descent: -4%discontinuation threshold 2%for minimum-maximum-search:search interval for the minimum: 30 ssearch interval for the 1st maximum: 30 ssearch interval for the 2nd maximum: 30 sminimum event time: 5 smaximum event time: 150 s______________________________________" ]
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] Not applicable. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not applicable. BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The invention relates generally to the field of equipment such as cables and conduits deployed on the bottom of a body of water. More specifically, the invention relates to devices for recovering such cables or conduits after they have been deployed on the water bottom for a selected length of time. [0005] 2. Background Art [0006] The invention is related to a device that is intended to be attached to equipment or material, e.g., a seismic sensor cable or a conduit, disposed on the bottom of a body of water such as a lake or the ocean. When so disposed, recovery can be difficult due to the device being covered with ocean bottom material. As a result, recovery of the equipment can be a slow difficult process. Recovery of the equipment requires that the equipment is pulled laterally and axially out of the entrapping bottom sediments. The equipment will eventually come out of the bottom sediments if pulled on with sufficient stresses and for a long enough period of time. A difficulty with the foregoing recovery method is that the equipment is often damaged from the stresses applied and personnel and recovery equipment spend a substantial amount of time pulling on the equipment to dislodge it from the water bottom sediment rather than attending to the other duties. [0007] Accordingly, there exists a need for better methods and devices for recovering equipment deployed on the bottom of a body of water. SUMMARY OF THE INVENTION [0008] A system according to one aspect of the invention for retrieving a device from the bottom of a body of water includes a clamp configured to be slidably affixed to the device above the water bottom. The clamp has a selectively engageable lock to fix a position of the clamp on the device. A line ratchet is coupled to the clamp. A line is disposed through the line ratchet. A first flotation device is coupled to one end of the line. A second flotation device is coupled to the other end of the line. The system includes means for applying tension to the line disposed proximate the second flotation device. The line ratchet is arranged to enable movement of the line therethrough toward the means for applying tension, and is also arranged to substantially prevent motion therethrough in the opposite direction. [0009] A method for retrieving a device disposed on the bottom of a body of water according to another aspect of the invention includes slidably affixing a cable clamp to a part of the device disposed above the water bottom. The cable clamp is moved proximate the water bottom. The clamp is locked in place on the device. Lifting force is applied to one end of a line. The line is functionally coupled to the clamp through an element enabling movement of the line in only one direction. Lifting force is applied to the other end of the line. The line is retracted from one of the ends thereof. The retracting includes moving the line through the element. [0010] Other aspects and advantages of the invention will be apparent from the following description and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS [0011] FIG. 1 shows an example water bottom device retrieval system according to the invention. [0012] FIG. 2 shows internal components of an example cable or conduit clamp according to the invention. [0013] FIG. 3 shows an example opening in a housing of the cable or conduit clamp. [0014] FIG. 4 shows a side view of the cable/conduit clamp of FIG. 3 including an actuator. [0015] FIG. 5 shows a top view of the cable/conduit clamp of FIG. 3 . [0016] FIG. 6 shows an example line of cable ratchet. DETAILED DESCRIPTION [0017] An example system for retrieving devices deployed on the bottom of a body of water is shown schematically in FIG. 1 . A device, such as a cable or conduit 26 may be deployed on the bottom of a body of water 10 such as a lake or the ocean. The cable or conduit 26 (referred to for convenience hereinafter as the “cable”) may be, for example, a seismic sensor cable. After the cable 26 has been deployed for a selected length of time, parts of the cable 26 may become partially or totally buried by water bottom sediment 28 . The weight of such sediment may make retrieval of the cable 26 by pulling upwardly on its axial end difficult and may risk breakage of or damage to the cable 26 by reason of excessive axial tension required to lift the cable 26 from the sediment 28 . [0018] The present system may include a first floatation device such as a buoy 12 coupled to a storage element 14 . The storage element 14 may be a bag or a reel (a bag is shown in FIG. 1 ) and is configured to store portions of the cable 26 that are lifted from the sediment 28 and water bottom using the system. The lifted portions of the cable 26 may be manually inserted into the storage element, or the storage element 14 may include automatic devices (not shown) for storing the lifted cable 26 . [0019] A second floatation device such as a buoy 18 may be coupled proximate one end of a lifting line, rope or cable 20 (hereinafter for convenience referred to as the “line”). The line 20 may be used to apply lifting force to the cable 26 by pulling on or near the end of the line 20 proximate the second floatation device 18 . Pulling may be performed by a winch (not shown) or similar device. The winch (not shown) may be associated with the second buoy 18 , or may be on a vessel (not shown). In the latter example, after the vessel mounted winch (not shown) is used to apply tension to the line 20 , the vessel (not shown) may be disconnected from the line 20 and allowed to attend to other functions. The second buoy 18 provides a location of the upper end of the line 20 for later retrieval as needed. [0020] The line 20 may be functionally coupled to a cable clamp 24 (explained below in more detail with reference to FIGS. 2 through 5 ). When axial tension is applied to the line 20 , the axial tension is transferred to the cable 26 through the cable clamp 24 . Such axial tension tends to lift the cable 26 from the sediment 28 , yet avoids applying large axial tension directly on the cable 26 . [0021] In the present example, the line 20 may be coupled to the cable clamp 24 using a one way motion elements such as a ratchet 22 or similar device to limit motion of the line 20 to one direction therethrough. As the line 20 is tensioned, the line 20 moves through the ratchet 22 . The other end of the line 20 may be coupled to a third floatation device or buoy 16 . As the tension on the line 20 is increased, the third flotation device 16 may be pulled beneath the water surface, depending on the weight of the sediment 28 covering the cable 26 . The tension on the line 20 may continue to be applied until the third buoy 16 moves proximate the ratchet 22 . The system may then be allowed to remain in such condition. During such time, the buoyant force exerted by the third buoy 16 will tend to lift the ratchet 22 and the connected cable clamp 24 , thus lifting the cable 26 from the sediment 28 . Lifting of the part of the cable 26 coupled to the clamp 24 may be considered completed when the third flotation device 16 becomes visible at the water surface. [0022] In using the present system, the cable clamp 24 is affixed to the exterior of the cable 26 at a location proximate the water surface, typically from a vessel (not shown). The line 20 will be fully extended so that the cable clamp 24 may move freely along the exterior of the cable until it reaches the portion of the cable 26 resting on the water bottom or proximate part of the cable 26 buried under sediment 28 . As will be further explained below with reference to FIGS. 2 through 5 , a locking device in the cable clamp 24 may then be applied so that the clamp 24 is no longer free to move along the cable 26 . At such time, the line 20 may be tensioned as explained above, such that in combination the buoyant force of the second flotation device 16 and the third flotation device 18 apply lifting force to the cable clamp 24 to urge the cable 26 from under the sediment 28 . [0023] An example locking device for the cable clamp 24 is shown schematically in FIG. 2 . The locking device may include two or more first wedge segments 24 B made, for example of plastic such as one sold under the trademark DELRIN, which is a registered trademark of E.I. DuPont de Nemours & Co., Wilmington Del. The first wedge segments 24 B may define a serpentine opening 27 for receiving the cable 26 therein. The first wedge segments have a generally tapered exterior surface 24 H configured to cooperate with a corresponding interior surface 24 J of second wedge segments 24 A. The first 24 B and second 24 A wedge segments may be disposed in a housing ( FIGS. 3 and 4 ), such that when longitudinal force is applied to the first wedge segments 24 B, they interact with the second wedge segments 24 A to laterally compress against the cable 26 in the opening 27 . Thus, the cable 26 is no longer free to move within the opening 27 . A serpentine opening such as shown at 27 may be preferable to a straight opening in some examples because the force exerted by pulling on the cable clamp ( 24 in FIG. 1 ) may be distributed over a longer axial segment of the cable 26 , thereby reducing risk of damage to the cable 26 . The cable in the serpentine state will apply the loading force to the center components of the cable superiorly to that of the straight cable in a clamp. The distribution radial of the forces between the outer jacket (not shown separately) of the cable 26 and to the center components (e.g., electrical conductors) with better prevent damage to the cable 26 . [0024] The housing is shown in FIG. 3 at 24 C. The housing 24 C may be a generally closed structure made from high strength material such as steel or aluminium. The housing 24 C may include a serpentine opening 24 D in one face thereof to enable affixing the cable clamp ( 24 in FIG. 1 ) onto the cable ( 26 in FIG. 1 ). The opening 24 D may be positioned to correspond to the opening in the second wedge segments ( 24 B in FIG. 2 ). The wedge segments ( 24 A, 24 B in FIG. 2 ) may be inserted into the housing through an opening 24 K in the longitudinal end of the housing 24 C as shown in FIG. 3 . In some examples, clamps, doors or baffles (not shown in FIG. 3 ) may be used to cover all or part of the opening 24 D after insertion of the cable 26 to ensure that the clamp 24 remains affixed to the cable 26 . [0025] FIG. 4 shows a side view of the assembled cable clamp 24 . The first wedge segments 24 B can be seen protruding from the longitudinal end of the housing 24 C. A cam mechanism 24 F is functionally coupled to a pull handle 24 G. The pull handle 24 G is coupled to the line ( 20 in FIG. 1 ). When tension is applied to the line ( 20 in FIG. 1 ) and thus to the pull handle 24 G, the pull handle 24 G rotates the cam mechanism 24 F to longitudinally urge the first wedge segments 24 B into the housing 24 C. As the first wedge segments 24 B are so urged, they interact with the second wedge segments as explained with reference to FIG. 2 to cause the first wedge segments 24 B to tightly grip the cable ( 26 in FIG. 1 ). A top view of the cable clamp 24 showing the cam mechanism 24 F is shown in FIG. 5 . [0026] FIG. 6 shows a cut away view of one example of the ratchet 22 . A sheave 22 C and an insert 22 D may be disposed in a housing 22 B such that a path or channel for the line 20 may be defined. A plurality of sprags 22 A or similar one way locking features may be affixed to the interior of the housing 22 B such that the line 20 is free to move in the direction indicated by the arrows, and is substantially stopped from moving in the opposite direction. [0027] As explained above with reference to FIG. 1 , when the system is deployed, the cable clamp 24 may be affixed to the exterior of the cable 26 and allowed to slide along the cable 26 to the water bottom. The line 20 may then be tensioned. Such tension will lock the locking mechanism in the cable clamp explained with reference to FIGS. 2 through 5 . Continued tension on the line 20 will cause the line to move so that the third buoy 16 is moved toward the cable clamp. Buoyant force of the third buoy will eventually lift the cable clamp with the cable attached. [0028] The foregoing process may be repeated by releasing locking mechanism on the cable clamp, releasing the line and allowing the cable clamp once again to slide to the water bottom. Alternatively, a plurality of additional cable clamps, lines and ratchets may be attached to other parts of the cable. [0029] A cable retrieval device according to the invention may increase efficiency of retrieval operations and may reduce risk of damage to devices disposed on the bottom of a body of water as contrasted with methods know in the art that include only pulling on an axial end of the device on the water bottom. [0030] While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
A system for retrieving a device from the bottom of a body of water includes a clamp configured to be slidably affixed to the device above the water bottom. The clamp has a selectively engageable lock to fix a position of the clamp on the device. A line ratchet is coupled to the clamp. A line is disposed through the line ratchet. A first flotation device is coupled to one end of the line. A second flotation device is coupled to the other end of the line. The system includes means for applying tension to the line disposed proximate the second flotation device. The line ratchet is arranged to enable movement of the line therethrough toward the means for applying tension, and is also arranged to substantially prevent motion therethrough in the opposite direction.
Briefly summarize the invention's components and working principles as described in the document.
[ "CROSS-REFERENCE TO RELATED APPLICATIONS [0001] Not applicable.", "STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not applicable.", "BACKGROUND OF THE INVENTION [0003] 1.", "Field of the Invention [0004] The invention relates generally to the field of equipment such as cables and conduits deployed on the bottom of a body of water.", "More specifically, the invention relates to devices for recovering such cables or conduits after they have been deployed on the water bottom for a selected length of time.", "[0005] 2.", "Background Art [0006] The invention is related to a device that is intended to be attached to equipment or material, e.g., a seismic sensor cable or a conduit, disposed on the bottom of a body of water such as a lake or the ocean.", "When so disposed, recovery can be difficult due to the device being covered with ocean bottom material.", "As a result, recovery of the equipment can be a slow difficult process.", "Recovery of the equipment requires that the equipment is pulled laterally and axially out of the entrapping bottom sediments.", "The equipment will eventually come out of the bottom sediments if pulled on with sufficient stresses and for a long enough period of time.", "A difficulty with the foregoing recovery method is that the equipment is often damaged from the stresses applied and personnel and recovery equipment spend a substantial amount of time pulling on the equipment to dislodge it from the water bottom sediment rather than attending to the other duties.", "[0007] Accordingly, there exists a need for better methods and devices for recovering equipment deployed on the bottom of a body of water.", "SUMMARY OF THE INVENTION [0008] A system according to one aspect of the invention for retrieving a device from the bottom of a body of water includes a clamp configured to be slidably affixed to the device above the water bottom.", "The clamp has a selectively engageable lock to fix a position of the clamp on the device.", "A line ratchet is coupled to the clamp.", "A line is disposed through the line ratchet.", "A first flotation device is coupled to one end of the line.", "A second flotation device is coupled to the other end of the line.", "The system includes means for applying tension to the line disposed proximate the second flotation device.", "The line ratchet is arranged to enable movement of the line therethrough toward the means for applying tension, and is also arranged to substantially prevent motion therethrough in the opposite direction.", "[0009] A method for retrieving a device disposed on the bottom of a body of water according to another aspect of the invention includes slidably affixing a cable clamp to a part of the device disposed above the water bottom.", "The cable clamp is moved proximate the water bottom.", "The clamp is locked in place on the device.", "Lifting force is applied to one end of a line.", "The line is functionally coupled to the clamp through an element enabling movement of the line in only one direction.", "Lifting force is applied to the other end of the line.", "The line is retracted from one of the ends thereof.", "The retracting includes moving the line through the element.", "[0010] Other aspects and advantages of the invention will be apparent from the following description and the appended claims.", "BRIEF DESCRIPTION OF THE DRAWINGS [0011] FIG. 1 shows an example water bottom device retrieval system according to the invention.", "[0012] FIG. 2 shows internal components of an example cable or conduit clamp according to the invention.", "[0013] FIG. 3 shows an example opening in a housing of the cable or conduit clamp.", "[0014] FIG. 4 shows a side view of the cable/conduit clamp of FIG. 3 including an actuator.", "[0015] FIG. 5 shows a top view of the cable/conduit clamp of FIG. 3 .", "[0016] FIG. 6 shows an example line of cable ratchet.", "DETAILED DESCRIPTION [0017] An example system for retrieving devices deployed on the bottom of a body of water is shown schematically in FIG. 1 .", "A device, such as a cable or conduit 26 may be deployed on the bottom of a body of water 10 such as a lake or the ocean.", "The cable or conduit 26 (referred to for convenience hereinafter as the “cable”) may be, for example, a seismic sensor cable.", "After the cable 26 has been deployed for a selected length of time, parts of the cable 26 may become partially or totally buried by water bottom sediment 28 .", "The weight of such sediment may make retrieval of the cable 26 by pulling upwardly on its axial end difficult and may risk breakage of or damage to the cable 26 by reason of excessive axial tension required to lift the cable 26 from the sediment 28 .", "[0018] The present system may include a first floatation device such as a buoy 12 coupled to a storage element 14 .", "The storage element 14 may be a bag or a reel (a bag is shown in FIG. 1 ) and is configured to store portions of the cable 26 that are lifted from the sediment 28 and water bottom using the system.", "The lifted portions of the cable 26 may be manually inserted into the storage element, or the storage element 14 may include automatic devices (not shown) for storing the lifted cable 26 .", "[0019] A second floatation device such as a buoy 18 may be coupled proximate one end of a lifting line, rope or cable 20 (hereinafter for convenience referred to as the “line”).", "The line 20 may be used to apply lifting force to the cable 26 by pulling on or near the end of the line 20 proximate the second floatation device 18 .", "Pulling may be performed by a winch (not shown) or similar device.", "The winch (not shown) may be associated with the second buoy 18 , or may be on a vessel (not shown).", "In the latter example, after the vessel mounted winch (not shown) is used to apply tension to the line 20 , the vessel (not shown) may be disconnected from the line 20 and allowed to attend to other functions.", "The second buoy 18 provides a location of the upper end of the line 20 for later retrieval as needed.", "[0020] The line 20 may be functionally coupled to a cable clamp 24 (explained below in more detail with reference to FIGS. 2 through 5 ).", "When axial tension is applied to the line 20 , the axial tension is transferred to the cable 26 through the cable clamp 24 .", "Such axial tension tends to lift the cable 26 from the sediment 28 , yet avoids applying large axial tension directly on the cable 26 .", "[0021] In the present example, the line 20 may be coupled to the cable clamp 24 using a one way motion elements such as a ratchet 22 or similar device to limit motion of the line 20 to one direction therethrough.", "As the line 20 is tensioned, the line 20 moves through the ratchet 22 .", "The other end of the line 20 may be coupled to a third floatation device or buoy 16 .", "As the tension on the line 20 is increased, the third flotation device 16 may be pulled beneath the water surface, depending on the weight of the sediment 28 covering the cable 26 .", "The tension on the line 20 may continue to be applied until the third buoy 16 moves proximate the ratchet 22 .", "The system may then be allowed to remain in such condition.", "During such time, the buoyant force exerted by the third buoy 16 will tend to lift the ratchet 22 and the connected cable clamp 24 , thus lifting the cable 26 from the sediment 28 .", "Lifting of the part of the cable 26 coupled to the clamp 24 may be considered completed when the third flotation device 16 becomes visible at the water surface.", "[0022] In using the present system, the cable clamp 24 is affixed to the exterior of the cable 26 at a location proximate the water surface, typically from a vessel (not shown).", "The line 20 will be fully extended so that the cable clamp 24 may move freely along the exterior of the cable until it reaches the portion of the cable 26 resting on the water bottom or proximate part of the cable 26 buried under sediment 28 .", "As will be further explained below with reference to FIGS. 2 through 5 , a locking device in the cable clamp 24 may then be applied so that the clamp 24 is no longer free to move along the cable 26 .", "At such time, the line 20 may be tensioned as explained above, such that in combination the buoyant force of the second flotation device 16 and the third flotation device 18 apply lifting force to the cable clamp 24 to urge the cable 26 from under the sediment 28 .", "[0023] An example locking device for the cable clamp 24 is shown schematically in FIG. 2 .", "The locking device may include two or more first wedge segments 24 B made, for example of plastic such as one sold under the trademark DELRIN, which is a registered trademark of E.I. DuPont de Nemours &", "Co., Wilmington Del.", "The first wedge segments 24 B may define a serpentine opening 27 for receiving the cable 26 therein.", "The first wedge segments have a generally tapered exterior surface 24 H configured to cooperate with a corresponding interior surface 24 J of second wedge segments 24 A. The first 24 B and second 24 A wedge segments may be disposed in a housing ( FIGS. 3 and 4 ), such that when longitudinal force is applied to the first wedge segments 24 B, they interact with the second wedge segments 24 A to laterally compress against the cable 26 in the opening 27 .", "Thus, the cable 26 is no longer free to move within the opening 27 .", "A serpentine opening such as shown at 27 may be preferable to a straight opening in some examples because the force exerted by pulling on the cable clamp ( 24 in FIG. 1 ) may be distributed over a longer axial segment of the cable 26 , thereby reducing risk of damage to the cable 26 .", "The cable in the serpentine state will apply the loading force to the center components of the cable superiorly to that of the straight cable in a clamp.", "The distribution radial of the forces between the outer jacket (not shown separately) of the cable 26 and to the center components (e.g., electrical conductors) with better prevent damage to the cable 26 .", "[0024] The housing is shown in FIG. 3 at 24 C. The housing 24 C may be a generally closed structure made from high strength material such as steel or aluminium.", "The housing 24 C may include a serpentine opening 24 D in one face thereof to enable affixing the cable clamp ( 24 in FIG. 1 ) onto the cable ( 26 in FIG. 1 ).", "The opening 24 D may be positioned to correspond to the opening in the second wedge segments ( 24 B in FIG. 2 ).", "The wedge segments ( 24 A, 24 B in FIG. 2 ) may be inserted into the housing through an opening 24 K in the longitudinal end of the housing 24 C as shown in FIG. 3 .", "In some examples, clamps, doors or baffles (not shown in FIG. 3 ) may be used to cover all or part of the opening 24 D after insertion of the cable 26 to ensure that the clamp 24 remains affixed to the cable 26 .", "[0025] FIG. 4 shows a side view of the assembled cable clamp 24 .", "The first wedge segments 24 B can be seen protruding from the longitudinal end of the housing 24 C. A cam mechanism 24 F is functionally coupled to a pull handle 24 G. The pull handle 24 G is coupled to the line ( 20 in FIG. 1 ).", "When tension is applied to the line ( 20 in FIG. 1 ) and thus to the pull handle 24 G, the pull handle 24 G rotates the cam mechanism 24 F to longitudinally urge the first wedge segments 24 B into the housing 24 C. As the first wedge segments 24 B are so urged, they interact with the second wedge segments as explained with reference to FIG. 2 to cause the first wedge segments 24 B to tightly grip the cable ( 26 in FIG. 1 ).", "A top view of the cable clamp 24 showing the cam mechanism 24 F is shown in FIG. 5 .", "[0026] FIG. 6 shows a cut away view of one example of the ratchet 22 .", "A sheave 22 C and an insert 22 D may be disposed in a housing 22 B such that a path or channel for the line 20 may be defined.", "A plurality of sprags 22 A or similar one way locking features may be affixed to the interior of the housing 22 B such that the line 20 is free to move in the direction indicated by the arrows, and is substantially stopped from moving in the opposite direction.", "[0027] As explained above with reference to FIG. 1 , when the system is deployed, the cable clamp 24 may be affixed to the exterior of the cable 26 and allowed to slide along the cable 26 to the water bottom.", "The line 20 may then be tensioned.", "Such tension will lock the locking mechanism in the cable clamp explained with reference to FIGS. 2 through 5 .", "Continued tension on the line 20 will cause the line to move so that the third buoy 16 is moved toward the cable clamp.", "Buoyant force of the third buoy will eventually lift the cable clamp with the cable attached.", "[0028] The foregoing process may be repeated by releasing locking mechanism on the cable clamp, releasing the line and allowing the cable clamp once again to slide to the water bottom.", "Alternatively, a plurality of additional cable clamps, lines and ratchets may be attached to other parts of the cable.", "[0029] A cable retrieval device according to the invention may increase efficiency of retrieval operations and may reduce risk of damage to devices disposed on the bottom of a body of water as contrasted with methods know in the art that include only pulling on an axial end of the device on the water bottom.", "[0030] While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein.", "Accordingly, the scope of the invention should be limited only by the attached claims." ]
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to novel polymers and copolymers of acrylamide and to methods for their preparation. 2. Description of the Prior Art The polymerization of acrylamide alone or with ethylenically unsaturated monomers in the presence of catalysts of the free radical type or redox type or in the presence of radiation is well known. Typical of such catalyst systems are the following described in the indicated references. ______________________________________Catalyst System Reference______________________________________thioureaogen Peroxide - Cu.sup.++ USP # 3,255,0722. Ammonium persulfate - Sodium metabisulfite - EDTA USP # 3,442,8033. Potassium persulfate - Fe.sup.++ Metabisulfite USP # 3,316,1814. Ammonium persulfate - Cu.sup.++ Sodium bisulfite USP # 3,332,9225. Potassium persulfate - Sodium metabisulfite USP # 3,450,6806. Sodium bromate - (Pat. No. unknown) Sodium sulfite7. Ammonium persulfate -nitrilotrispropionamide USP # 3,002,9608. Free radicals So. Africa Patent 69-1, 065/9699. Spray drying of catalyst USP # 3,644,30510. Co.sup.60 - gamma ray Brit. Pats. 1,139,917/ 1969 and 1,337,109/197311. Co.sup.60 - gamma ray or presence of systems: benzoil peroxide - N,N'- dimethylaniline; t. - butylhydroper-dimethylaniline' Chemical Abstracts 196912. Co.sup.60 - gamma ray or in the presence of complex of potassium diaquodioxalo manganese USP # 3,736,241 {K [ Mn (C.sub.2 O.sub.4).sub.2 (H.sub.2 O).sub.2 ]}______________________________________ The above described catalyst systems are not without their shortcomings, however, in polymerization reactions involving acrylamide. First of all, the presence of air cannot be tolerated in acrylamide polymerizations employing these catalyst systems for the excess oxygen prematurely terminates the reaction resulting in a final product having an undesirably low molecular weight. Consequently, it is necessary with these catalyst systems to either evacuate the reaction vessel of air prior to initiating the polymerization or to effect the polymerization in the presence of an inert gas such as nitrogen or argon. Other disadvantages associated with these catalysts is the fact that the conversion is less than one hundred percent and the time of reaction is unduly long, requiring in general in excess of twelve hours. A further objection, in addition to the inert atmosphere required, to the use in acrylamide polymerizations of the initiator complex described in U.S. Pat. No. 3,736,241 for the polymerization of acrylonitrile is that the catalyst decomposes to evolve noxious carbon monoxide. SUMMARY OF THE INVENTION Accordingly, it is a principal object of this invention to provide novel polymers and copolymers of acrylamide by a method wherein the presence of air is immaterial and virtually complete conversion of the monomer reactant or reactants is obtained. Another object of the invention is to provide a method for acrylamide polymerization wherein the time of reaction is considerably shorter than that of prior art processes and no objectionable gases are produced by the reaction. Yet another object of the invention is to provide novel film-forming and fiber-forming polymeric materials. A further object of the invention is to provide novel foamed and unfoamed polyimides from commercially available materials which polyimides have a high resistance to chemical attack, and a low specific gravity as, for instance, less than 0.5. A still further object of the present invention is to prepare polyimides possessing high fire retardant properties which polyimides do not depend on the addition of inorganic halide or halogenated organic additives for their flame retardant properties. Other objects and advantages of the invention will become apparent from the following description. The objects and advantages of the present invention are achieved by polymerizing in a liquid medium a member of the group selected from acrylamide and mixtures of acrylamide and at least one ethylenically unsaturated monomer copolymerizable therewith in the presence of a catalyst having the structure: ##STR3## wherein: Q = Na, K, NH 4 , Ca, Ba or metals of group IA and IIA. n = 2 to 5 ##STR4## Me = Ti, Mn, Mo, Zr, W or other multi-valent metals x = o to 1 a,b,c each = 0 to 1 a+b+c+d = valence of Me DETAILED DESCRIPTION OF THE INVENTION Unlike the catalyst systems noted above, including UV and ionizing radiation, the catalysts employed in the method of the present invention are not free radical initiators. With radical initiators acrylamide can polymerize to polymers with C--C chains as follows: ##STR5## The catalysts of this invention are in equilibrium solutions such as Complex Me catalysts→ [acid⃡base + H*].sup.** = K** where K** is the transition constant of the reaction. The catalysts improve the resonant structure of the acrylamide in solution, as for example: ##STR6## The catalysts of the invention, in contrast to the catalyst systems noted previously, polymerize acrylamide and mixtures of acrylamide and ethylenically unsaturated monomers via the imine-linkages in the following manner: ##STR7## While the exact mechanism of the polymerization reaction is not clearly understood it is believed that it proceeds via amide anions which are probably formed by a H.sup.(+) shift from the amino group to the ceto carbonyl. Thus, while there is no desire to be held to any particular theory of operation, it has nevertheless been demonstrated that polymer compositions prepared by the method of this invention are polyimides as opposed to C--C chained polymers containing amide, i.e. ##STR8## appendages and possess unique and in many respects superior properties to those prepared by the heretofore known methods. Another surprising advantage of the method of the invention resides in the unexpected finding that the oxalate complex catalysts employed in the polymerization breakdown to harmless carbon dioxide. On the other hand, other oxalic radical generating catalysts such as the oxalic complex, manganese diaquodioxalate potassium, employed in the polymerization of U.S. Pat. No. 3,736,241 in addition to forming C--C backbone polymers, as aforementioned, breakdown into toxic carbon monoxide. Among the suitable catalysts contemplated for use in the method can be included the following: Compound 1: K[Mn(C 2 O 4 ) 2 (H 2 O) 2 ] · 2H 2 O Compound 2: K[Mn(C 3 H 2 O 4 ) 2 (H 2 O) 2 ] · 2H 2 O Compound 3: (NH 4 ) 2 [TiO(C 2 O 4 ) 2 ] · 3H 2 O Compound 4: K 2 [TiO(C 2 O 4 ) 2 ] · 2H 2 O Compound 5: Na 2 [TiO(C 2 O 4 ) 2 ] · 3H 2 O Compound 6: Ba[TiO(C 2 O 4 ) 2 ] · 4H 2 O Compound 7: Ca[TiO(C 2 O 4 ) 2 ] · 5H 2 O Compound 8: Na 2 [WO 2 (OH) 2 (C 2 O 4 )] · n H 2 O (n = 1 to 3) Compound 9: (NH 4 ) 2 [WO 3 (C 2 O 4 )] · H 2 O Compound 10: (NH 4 ) 2 [MoO 3 ) (C 2 O 4 )] · n H 2 O (n = 1 to 3) Compound 11: Na 2 [(MoO 3 ) (C 2 O 4 )] · 3H 2 O Compound 12: K 4 [Zr(C 2 O 4 ) 4 ] · 5H 2 O Of these oxalate complexes, the compounds 1 and 2 are preferred for they produce the most efficient reaction. Moreover, they readily decompose to CO 2 at room temperature which makes them most desirable in the production of foamed polyimides as will be discussed below. The catalyst concentration will vary depending primarily upon the particular catalyst selected and the specific reaction conditions employed. In general the amount of catalyst will fall in the range of about 0.5 to 15 % by weight of the monomer or monomers employed. In a preferred embodiment of the invention, especially when a foam polymeric product is desired there is employed in combination with oxalate complex catalyst an alkaline persulfate. The presence of the persulfate assists in breaking down the oxalate complex catalyst to evolve large amounts of CO 2 . Suitable persulfates are alkali persulfates such as sodium and potassium persulfate and ammonium persulfate. When used, the persulfates are generally added in the same range as that of the oxalate complex catalyst. The polymers produced by the method of the invention have the repeating unit of structure A or structure C, or both structures A and C and may be homopolymers of acrylamide or interpolymers including copolymers and terpolymers of acrylamide and at least one ethylenically unsaturated monomer copolymerizable therewith. The polymers produced by the method of the invention are curable and may be substantially linear or crosslinked polymeric materials depending primarily upon whether a crosslinking agent is employed in the reaction and/or the comonomers used have functional groups naturally crosslinkable during the polymerization. Homopolymers prepared by the method of the invention may be represented by structure A or structure C or both structures A and C with the structure repeated at least 15 times, usually up to 50 or more. Interpolymers or copolymers prepared by the method of the invention have the repeating units shown in structure D and structure E, wherein Z is H or an organic functional group. Preferably Z is selected from H,-COOR wherein R is H or alkyl, --CH 2 --, --OH, ##STR9## --CH, --NH 2 , --C.tbd.N, piperazine, hydantion, aryl or naphthyl and cyclohexyl groups. In these structures m and n represent respectively the average number of acrylamide monomer units and CH 2 ═CH-Z monomer units in the polymer per 100 monomer units of the polymer, the sum of m + n totaling 100. Preferably n is about 50 to about 75 and m is 50-25. Particularly preferred terpolymers of the invention are solid crosslinked polymers comprising copolymerized acrylamide, acrylonitrile and a copolymerized ethylenically unsaturated carboxylic acid, ester or anhydride such as acrylic acid, itaconic acid, etc., and the anhydrides and esters, thereof. Examples of suitable comonomers, one or more of which can be polymerized with acrylamide in accordance with the method of the invention, are the acrylates, and acrylate derivatives: piperazine, hydantion, cyclohexyl acrylate groups, and α-substituted acrylates wherein the α-substituent is alkyl such as methyl, ethyl, propyl and the like; aryl such as phenyl, naphthyl and the like; the ester moiety being alkyl such as methyl, ethyl, propyl and the like; aryl such as phenyl, naphthyl and the like; vinyl ethers, e.g. methyl, ethyl, propyl and higher alkyl; 2-(N,N diethanol amino) ethyl acrylate, acrylamide, and substituted acrylamides e.g. methacrylamide, N-methylacrylamide, N,N-dimethylacrylamide; N-vinylacetamide, acrylic acid, acrylonitrile, allyl acetate, allyl alcohol, crotonic acid, dimethylaminoethylvinyl sulfide, diethylhexyl maleate, didodecyl maleate, fumaramide, itaconic acid, methacrylic acid, methoxystyrene, methyl vinyl ketone, 3-methyl-N-vinylpyrrolidone, 2-methyl-5-vinylpyridine, styrene, trichloroethylene, vinylcaprolactam, vinylcarbazole, vinylimidazole, vinyl laurate, vinyl benzimidazole, 1,3- and 1,4-butanediol monomethacrylate, vinyloxazolidinone, vinyl oxyethylurea, vinyl propionate, vinyl pyridine, vinyl stearate, vinyl acetate (and the derived vinyl alcohol,) diolpiperazine acrylate (or diacrylate) derivatives, hydantion acrylate or diacrylate, epoxy hydantion acrylates or other alkyl or aryl epoxy acrylate derivatives, Zn, Mg, Ca, Ba, Pb, Na acrylates or methacrylates. The homopolymers and interpolymers of the present invention may be crosslinked to provide tough, chemically stable, elastomeric products, highly insoluble in organic solvents, as well as in organic and inorganic acids and bases. The crosslinking agents that are suitably employed are those conventional crosslink agents containing two or more functional groups capable of taking part in the polymerization reaction so as to provide a polymeric material having a crosslinked three-dimensional structure. The crosslinking agent selected in any given case will generally depend upon the particular reactive groups on the polymeric chains to be crosslinked. Likewise, the concentration of crosslinking agent used will vary depending on the agent and the degree of crosslinking desired. In general, at least 2% up to 20% by weight based upon the monomers is employed. Accordingly, suitable crosslinking agents that have been found particularly applicable in the method of the invention are those having the structure: R (Q).sub.p wherein Q is selected from --OH, --SH, --Cl, --NCO, ##STR10## and ##STR11## where R and R' are polyvalent organic radicals of 2 to 12 carbon atoms. R and R' are preferably divalent or trivalent aliphatic or aromatic hydrocarbons. Illustrative of these crosslinking agents can be included ethylene glycol, propylene glycol, 1,2,3-propane triol, 1,2-ethane dithiol, 1,2,3-propane trithiol, 1,6-cyclohexane diol, 1,6-benzene diol, pentaerythritol, aryl, alkyl, hydantion diisocyanate derivatives, and other alkyl or aryl diisocyanate derivatives diethanolamine, triethanolamine, furan dianhydride, pyrazine dianhydride, pyromellitic dianhydride, urea, urine, melamine, melamine allyl derivatives, epihydrin alcohol, diacrylate derivatives, and the like. Advantageously, flame retardants are included in the polymerization reaction of the invention. The preferred types of flame retardants are those which bond chemically to the polymer so as to provide prolonged flame resistance to the polymeric material. Illustrative of such polymers are halogenated dienes such as hexachlorobutadiene, poly (phosphoramidopentachloro dienylurea), poly (phosphamidopentachlorodienylurea), poly (phosphorylnitrure) and halogenated unsaturated organic salts and esters such as 1,1-dichlorovinyl diethyl phosphate, bis (β-chloroethyl) vinyl phosphate, triethanolamino bisallyl chlorophosphoric acid and Phosgard C22R. In general flame retardants are added in amounts ranging from 0.5 to 25% by weight of the monomers. The polyimide homopolymers prepared by the invention range from viscous materials to solids depending upon their intended use and are characterized by average molecular weights of at least 1,000 up to 1,000,000 or more. In the interpolymers of the invention, the proportions of the various monomer units and their distribution along the carbon-carbon chain, and the length of the chain can vary over a wide range, thereby providing a family of polymers having different molecular weights and solubilities and differing in other important properties which render certain of these polymers particularly suited for specific applications. As in the case of the homopolymers the interpolymers range from viscous materials to high molecular weight solids. In instances where one or more of the monomers contain crosslinkable groups, a solid crosslinked product will generally result. Thus, while the composition and structure of the interpolymers can vary over wide ranges, nevertheless the interpolymers comprise about 30 to 90 mole %, preferably 50 to 85 mole % acrylamide and 70 to 10 mole %, preferably 50 to 15 mole % of at least one copolymerizable ethylenically unsaturated monomer. The polymerization of the monomer or monomers usually can be initiated at room temperature although some mild heating may be necessary in certain polymerization reactions. These reactions are exothermic and are accompanied by a release of heat causing an increase in reactant temperature. While normal temperature increases can be accomodated with no particular problem, too high of a rate for the exothermic polymerization reaction would cause a significant increase in temperature and "run away" polymerization. Thus, with most reactant systems it is preferred that the reaction temperature be conducted at about 20° to 60° C. If necessary, the reaction mixture may be cooled sufficiently to prevent excessive temperatures. The method of the invention can be carried out by simply mixing thoroughly as by homogenization at room temperature the reactants and catalysts. If desired a mutual solvent for the reactants and catalysts can be included. Suitable solvents are dimenthyl formamide, dimethyl sulfoxide, alkanols, dioxane and ketones. The materials are continually stirred until the solution begins to gel which is generally in about 1 - 3 1/2 hours. The gelling solution may then be case or poured into a desired form and the polymerization allowed to go to completion. As a preferred embodiment of the present invention there is included in the polymerization reaction a cocatalyst strong inorganic acid such as sulfuric acid or phosphoric acid and preferably a mixture of such acids. It has been found that the presence of the acids increases the efficiency of the catalyst system in that they convert all the oxalic groups to CO 2 . - and CO 2 thereby preventing conversion of the oxalic acid groups to oxalate salts. When employed the acids are added in concentrations of about 1 to 45 % by weight of monomer/catalyst. Optionally, and as another embodiment of the invention, the polymerization may be assisted by effecting the reaction in the presence of radiation such as ultraviolet light, gamma ray, electron beam and other forms of ionizing radiation. Often this radiation will be used in place of the persulfate component. When used, the dosage of ionizing radiation will fall in the range of 0.01 Megarads/hr to 10 Megarads/hr. According to one specific mode of preparing crosslinked polymeric compositions of the invention, a solution of one or more crosslinking agents such as urea in an acid such as phosphoric acid, sulfuric acid or mixtures thereof, is prepared. There is then prepared a separate solution of the monomer or monomers in a suitable solvent such as dimethyl sulfoxide, alkanol, water and the like, which solution is added to the acid solution with cooling. Any flame retardants, dispersing agents and filler materials may then be added. Lastly, yet a third solution of the oxalate complex catalyst alone or in combination with the alkaline persulfate in either a solvent which is also a solvent for the monomers or in one of the monomers is prepared. This third solution is added to the mixture of previous solutions and the resulting solution brought to reaction temperature. As aforementioned the polymerization is complete within about 3 1/2 hours, often within 1 or 2 hours. Upon completion of the polymerization reaction, a polymeric foam product either of the homopolymer or interpolymers of the invention may be prepared by simply heating the polymer in the presence of air at an elevated temperature, for example, to a temperature of at least 150° C, usually up to 300° C, preferably about 200° C to 250° C. The heating effects a breakdown in the oxalate complex to evolve CO 2 which becoming entrapped in the polymer forms a foamed product. The polymeric materials of the present invention have wide industrial application. In addition to the general fields of fiber, film and mold products, the foam products have excellent thermoisolation properties, very high flame resistance with a limiting oxygen index up to 95, very high chemical resistance and good physical properties in comparison with all organic foams and fibrous materials. The following examples are included to further illustrate the present invention but are not to be considered as limiting the invention in any respect. EXAMPLE I The following compounds (given by weight ratios) are homogenized at room temperature: ______________________________________Sulfuric/Phosphoric Acid (8/2 ratio) 25Urea Oxalate (or derivatives) 3Acrylamide (or derivatives) 12.5Hexachlorobutadiene 5.5Dimethylformamide/H.sub.2 O 1.5/0.5Zinc methacrylate 6.0Complex Oxalic (Compound 1) 0.082-(N,N diethanolamino) ethyl acrylate 3.5Potassium Persulfate 0.04Poly(phosphoramido pentachloro dienyl urea) 5.5______________________________________ These materials are stirred in an open container until a homogeneous solution is obtained and is continued to be stirred for an additional 120 minutes. When the solution begins to gel the solution is poured into a form and polymerization allowed to go to completion forming an elastomeric solid. Heating this solid to approximately 200° C in an oven or a tunnel (not requiring any special atmospheres) forms a fibrous foamed material in a few minutes. EXAMPLE II The process of Example I is repeated with the following composition: ______________________________________Sulfuric Acid (concentrated) 18or Phosphoric Acid (concentrated)Ureaperoxidate (or derivatives) 5Acrylamide (or derivatives) 13Dimethylformamide 3.3Furandianhydride (or other anhydrides) 1Hexachlorobutadiene 3.7Calcium methacrylate 7.52-Chloroethylchlorophosphate 1.5Poly(phospho amido penta chloro dienyl urea) 4.0Complex Oxalic (Compound 1) 0.01Potassium Persulfate 0.01______________________________________ EXAMPLE III The process of Example I is followed using the following compositions: ______________________________________H.sub.2 SO.sub.4 /H.sub.3 PO.sub.4 (4/1 ratio) 15Urea (or derivatives) 5Acrylamide (or derivatives) 50Dimethylformamide/H.sub.2 O (azeotrop mixture) 5Hexachlorobutadiene 3Triethanolaminobisdiallylchloro- phosphoric acid 2Complex Oxalic (Compound 2) 0.01K Persulfate 0.01Zinc acrylate 6.0______________________________________ EXAMPLE IV The process of Example I is followed with the following compositions: ______________________________________H.sub.2 SO.sub.4 /H.sub.3 PO.sub.4 (4/1 ratio) 3Urea (derivatives) 5Acrylamide (or derivatives) 10Dimethylformamide 1Epoxy -5,5 dimethylhydantion acrylate 7.7Acrylonitrile 1.5Barium methacrylate 8.2Poly(phosphorylnitrure) 5.5Hexachlorobutadiene 5Complex Oxalic (Compound 2) 0.01K Persulfate 0.01______________________________________ EXAMPLE V Example IV is repeated except that persulfate is not used but ultraviolet light in the range of 3000 to 7000 A or ionizing radiation of about 0.5 Megarads/hr is employed. The time of reaction is 5 to 12 minutes to form the polymer material. EXAMPLE VI The process of Example I is followed using the following compositions: ______________________________________Sulfuric Acid 10Phosphoric Acid 4Ureaperoxide 6Acrylamide 6Acrylonitrile 1Dimethylformamide 2Furandianhydride 0.1Hexachlorobutadiene 1Zinc methacrylate 4.8Complex Oxalic (Compound 1) 0.01Poly(phosphor amido penta chloro dienyl urea) 3.3Persulfate (K or NH.sub.4) 0.01______________________________________ EXAMPLE VII Example VI is repeated but substituting for the persulfate the radiation of Example V. EXAMPLE VIII Example VI is repeated with the addition of ______________________________________ Itaconic Acid 1 Sodium acrylate 3.5______________________________________ to the ingredients. EXAMPLE IX The process of Example I is followed with the compositions: ______________________________________Sulfuric Acid 18Urea/(Urea Oxalate) (1.0/0.3 ratio) 4Acrylamide 20Hexachlorobutadiene 4Ethanol 15Poly(phosphoryl nitrure) 7.5Complex Oxalic (Compound 2) 0.08K Acrylate 10.0K Persulfate 0.03______________________________________ EXAMPLE X Example IX is repeated substituting for the persulfate the radiation of Example V. EXAMPLE XI A. The process of Example I is repeated with the following compositions: ______________________________________Sulfuric/Phosphoric Acids (4/1 ratio) 10Acrylamide 8Urine 5Urea 2Zinc Acrylate 5.75Complex Oxalic (Compound 1) 0.08Poly(phospho amido penta chloro dienyl urea) 5.5Ammonium Persulfate 0.04______________________________________ This mixture will result in an elastomeric compound. B. The following addition may be made to the mixture in Example XI A.: ______________________________________K methacrylate 8.2Styrene/Acrylonitrile (3/1 ratio) 0.5 to 2______________________________________ This addition results in an improvement of the elastic properties of the material detailed in Example XI A. C. The following addition may be made to the materials listed in Example XI A.: ______________________________________Isoprene 0.5 to 3Dimethylformamide 1 to 3______________________________________ D. The following addition may be made to the materials in Example XI A.: ______________________________________Dianhydride (furan, pyrazine,pyromellitic or other anhydrides) 0.01 to 0.1Dimethylformamide 1 to 7______________________________________ The resultant elastomer will have improved mechanical strength compared to the material listed in Example XI A. EXAMPLE XII The process of Example I is followed with the following compositions: ______________________________________Sulfuric Acid 20Phosphoric Acid 10Urea 10Acrylamide 30Acrylonitrile 6Styrene 6Zinc acrylate 6.8Dimethylformamide 4Poly(phosphor amido pentachloro dienyl urea) 2.5Hexachlorobutadiene 5______________________________________ EXAMPLE XIII The materials in Example XII are mixed with metal or metal oxides (aluminum, alumina, copper or others), glass or glass binder, in the following ratios: 0.5 to 2.5 part by weight of metal, metal oxide or glass and 5 to 15 parts by weight of polymer solution. These additions improve the physical properties of the material. EXAMPLE XIV To 43 units of phosphoric acid gradually is added 45 units of urea, while the mixture is stirred constantly. To decrease the viscosity of the solution the temperature is increased to about 30° C. When the urea is completely dissolved, there is added another dimethylsulfoxide solution containing: ______________________________________Acrylamide 180Zinc methacrylate 25Acrylonitrile 53Poly(phosphoryl nitrure) 10Methylmethacrylate 40______________________________________ Continuous stirring is maintained. Using another 9 to 14 units of methylmethacrylate 0.5 to 1.5 units of compound 1 is brought to a solution. This solution is then added to the previous mixture. The temperature is raised to 40° C; meanwhile the solution is stirred constantly. The solution will gel after some time, at which the stirring is stopped. After the material has fully polymerized, it is foamed at about 200° C. EXAMPLE XV The previous example is repeated with the addition to the phosphoric acid solution of 0.5% by weight of hexachlorobutadiene based on the monomers and 1.2% by weight melamine based on the urea. The resultant polymer is foamed at 190° C. All the crosslinked polymeric products produced by Examples I through XV are fibrous materials thermostable to 150° C and flame resistant. When the fibrous material is held in a Bunsen burner flame (over 95% oxygen), the fibrous material carbonizes directly without flaming or developing much smoke, and when removed from the flame, the material does not flame and does not burn. The polymeric products when subjected to chemical solubility tests for 216 hours at room temperature were found not soluble in the following chemicals: water, aqueous alkaline solution (n/10 NaOH), sulfuric acid (conc. 98%), formic acid (conc. 90.3%), phosphoric acid (conc.), acetic acid (conc.), oxidant mixture K 2 Cr 2 O 7 -H 2 SO 4 conc.), acetic anhydride, benzene, aromatic hydrocarbons (gasoline), cyclohexanone, chlorobenzene, tetrahydrofuran (THF), methanol, hexane, dichloromethane, methylenechloride, ethylene chloro bromide, pyridine, dimethylformamide, dimethylsulfoxide, ammonium hydroxide (conc. 28.9%). The specific gravity of the products falls in the range of approximately 0.018 to 0.5 and the products exhibit no liquid absorption. Further, the products are characterized by a relative humidity of 2.5 - 3.5% (no static electricity build-up) and high thermal expansion and shock absorption properties.
Elastomeric, chemically stable, flame resistant polymers are obtained by polymerizing acrylamide or mixtures of acrylamide and at least one ethylenically unsaturated monomer copolymerizable therewith in the presence of a catalyst having the structure: ##STR1## wherein: Q = Na, K, NH 4 , Ca or Ba n = 2 to 5 ##STR2## Me = Ti, Mn, Mo, Zr or W x = 0 to 1 a, b, c each = 0 to 1 a+b+c+d = valence of Me. The catalyst may be used alone as well as with UV, electron beam, ionizing radiation and combinations of these and with general redox systems known in the literature.
Summarize the patent information, clearly outlining the technical challenges and proposed solutions.
[ "BACKGROUND OF THE INVENTION 1.", "Field of the Invention This invention relates to novel polymers and copolymers of acrylamide and to methods for their preparation.", "Description of the Prior Art The polymerization of acrylamide alone or with ethylenically unsaturated monomers in the presence of catalysts of the free radical type or redox type or in the presence of radiation is well known.", "Typical of such catalyst systems are the following described in the indicated references.", "______________________________________Catalyst System Reference______________________________________thioureaogen Peroxide - Cu.", "sup.", "++ USP # 3,255,0722.", "Ammonium persulfate - Sodium metabisulfite - EDTA USP # 3,442,8033.", "Potassium persulfate - Fe.", "sup.", "++ Metabisulfite USP # 3,316,1814.", "Ammonium persulfate - Cu.", "sup.", "++ Sodium bisulfite USP # 3,332,9225.", "Potassium persulfate - Sodium metabisulfite USP # 3,450,6806.", "Sodium bromate - (Pat.", "No. unknown) Sodium sulfite7.", "Ammonium persulfate -nitrilotrispropionamide USP # 3,002,9608.", "Free radicals So.", "Africa Patent 69-1, 065/9699.", "Spray drying of catalyst USP # 3,644,30510.", "Co.sup[.", "].60 - gamma ray Brit.", "Pats.", "1,139,917/ 1969 and 1,337,109/197311.", "Co.sup[.", "].60 - gamma ray or presence of systems: benzoil peroxide - N,N'- dimethylaniline;", "t. - butylhydroper-dimethylaniline'", "Chemical Abstracts 196912.", "Co.sup[.", "].60 - gamma ray or in the presence of complex of potassium diaquodioxalo manganese USP # 3,736,241 {K [ Mn (C.", "sub[.", "].2 O.sub[.", "].4).", "sub[.", "].2 (H.", "sub[.", "].2 O).", "sub[.", "].2 ]}______________________________________ The above described catalyst systems are not without their shortcomings, however, in polymerization reactions involving acrylamide.", "First of all, the presence of air cannot be tolerated in acrylamide polymerizations employing these catalyst systems for the excess oxygen prematurely terminates the reaction resulting in a final product having an undesirably low molecular weight.", "Consequently, it is necessary with these catalyst systems to either evacuate the reaction vessel of air prior to initiating the polymerization or to effect the polymerization in the presence of an inert gas such as nitrogen or argon.", "Other disadvantages associated with these catalysts is the fact that the conversion is less than one hundred percent and the time of reaction is unduly long, requiring in general in excess of twelve hours.", "A further objection, in addition to the inert atmosphere required, to the use in acrylamide polymerizations of the initiator complex described in U.S. Pat. No. 3,736,241 for the polymerization of acrylonitrile is that the catalyst decomposes to evolve noxious carbon monoxide.", "SUMMARY OF THE INVENTION Accordingly, it is a principal object of this invention to provide novel polymers and copolymers of acrylamide by a method wherein the presence of air is immaterial and virtually complete conversion of the monomer reactant or reactants is obtained.", "Another object of the invention is to provide a method for acrylamide polymerization wherein the time of reaction is considerably shorter than that of prior art processes and no objectionable gases are produced by the reaction.", "Yet another object of the invention is to provide novel film-forming and fiber-forming polymeric materials.", "A further object of the invention is to provide novel foamed and unfoamed polyimides from commercially available materials which polyimides have a high resistance to chemical attack, and a low specific gravity as, for instance, less than 0.5.", "A still further object of the present invention is to prepare polyimides possessing high fire retardant properties which polyimides do not depend on the addition of inorganic halide or halogenated organic additives for their flame retardant properties.", "Other objects and advantages of the invention will become apparent from the following description.", "The objects and advantages of the present invention are achieved by polymerizing in a liquid medium a member of the group selected from acrylamide and mixtures of acrylamide and at least one ethylenically unsaturated monomer copolymerizable therewith in the presence of a catalyst having the structure: ##STR3## wherein: Q = Na, K, NH 4 , Ca, Ba or metals of group IA and IIA.", "n = 2 to 5 ##STR4## Me = Ti, Mn, Mo, Zr, W or other multi-valent metals x = o to 1 a,b,c each = 0 to 1 a+b+c+d = valence of Me DETAILED DESCRIPTION OF THE INVENTION Unlike the catalyst systems noted above, including UV and ionizing radiation, the catalysts employed in the method of the present invention are not free radical initiators.", "With radical initiators acrylamide can polymerize to polymers with C--C chains as follows: ##STR5## The catalysts of this invention are in equilibrium solutions such as Complex Me catalysts→ [acid⃡base + H*].", "sup.", "** = K** where K** is the transition constant of the reaction.", "The catalysts improve the resonant structure of the acrylamide in solution, as for example: ##STR6## The catalysts of the invention, in contrast to the catalyst systems noted previously, polymerize acrylamide and mixtures of acrylamide and ethylenically unsaturated monomers via the imine-linkages in the following manner: ##STR7## While the exact mechanism of the polymerization reaction is not clearly understood it is believed that it proceeds via amide anions which are probably formed by a H.sup.", "(+) shift from the amino group to the ceto carbonyl.", "Thus, while there is no desire to be held to any particular theory of operation, it has nevertheless been demonstrated that polymer compositions prepared by the method of this invention are polyimides as opposed to C--C chained polymers containing amide, i.e. ##STR8## appendages and possess unique and in many respects superior properties to those prepared by the heretofore known methods.", "Another surprising advantage of the method of the invention resides in the unexpected finding that the oxalate complex catalysts employed in the polymerization breakdown to harmless carbon dioxide.", "On the other hand, other oxalic radical generating catalysts such as the oxalic complex, manganese diaquodioxalate potassium, employed in the polymerization of U.S. Pat. No. 3,736,241 in addition to forming C--C backbone polymers, as aforementioned, breakdown into toxic carbon monoxide.", "Among the suitable catalysts contemplated for use in the method can be included the following: Compound 1: K[Mn(C 2 O 4 ) 2 (H 2 O) 2 ] · 2H 2 O Compound 2: K[Mn(C 3 H 2 O 4 ) 2 (H 2 O) 2 ] · 2H 2 O Compound 3: (NH 4 ) 2 [TiO(C 2 O 4 ) 2 ] · 3H 2 O Compound 4: K 2 [TiO(C 2 O 4 ) 2 ] · 2H 2 O Compound 5: Na 2 [TiO(C 2 O 4 ) 2 ] · 3H 2 O Compound 6: Ba[TiO(C 2 O 4 ) 2 ] · 4H 2 O Compound 7: Ca[TiO(C 2 O 4 ) 2 ] · 5H 2 O Compound 8: Na 2 [WO 2 (OH) 2 (C 2 O 4 )] · n H 2 O (n = 1 to 3) Compound 9: (NH 4 ) 2 [WO 3 (C 2 O 4 )] · H 2 O Compound 10: (NH 4 ) 2 [MoO 3 ) (C 2 O 4 )] · n H 2 O (n = 1 to 3) Compound 11: Na 2 [(MoO 3 ) (C 2 O 4 )] · 3H 2 O Compound 12: K 4 [Zr(C 2 O 4 ) 4 ] · 5H 2 O Of these oxalate complexes, the compounds 1 and 2 are preferred for they produce the most efficient reaction.", "Moreover, they readily decompose to CO 2 at room temperature which makes them most desirable in the production of foamed polyimides as will be discussed below.", "The catalyst concentration will vary depending primarily upon the particular catalyst selected and the specific reaction conditions employed.", "In general the amount of catalyst will fall in the range of about 0.5 to 15 % by weight of the monomer or monomers employed.", "In a preferred embodiment of the invention, especially when a foam polymeric product is desired there is employed in combination with oxalate complex catalyst an alkaline persulfate.", "The presence of the persulfate assists in breaking down the oxalate complex catalyst to evolve large amounts of CO 2 .", "Suitable persulfates are alkali persulfates such as sodium and potassium persulfate and ammonium persulfate.", "When used, the persulfates are generally added in the same range as that of the oxalate complex catalyst.", "The polymers produced by the method of the invention have the repeating unit of structure A or structure C, or both structures A and C and may be homopolymers of acrylamide or interpolymers including copolymers and terpolymers of acrylamide and at least one ethylenically unsaturated monomer copolymerizable therewith.", "The polymers produced by the method of the invention are curable and may be substantially linear or crosslinked polymeric materials depending primarily upon whether a crosslinking agent is employed in the reaction and/or the comonomers used have functional groups naturally crosslinkable during the polymerization.", "Homopolymers prepared by the method of the invention may be represented by structure A or structure C or both structures A and C with the structure repeated at least 15 times, usually up to 50 or more.", "Interpolymers or copolymers prepared by the method of the invention have the repeating units shown in structure D and structure E, wherein Z is H or an organic functional group.", "Preferably Z is selected from H,-COOR wherein R is H or alkyl, --CH 2 --, --OH, ##STR9## --CH, --NH 2 , --C.", "tbd.", "N, piperazine, hydantion, aryl or naphthyl and cyclohexyl groups.", "In these structures m and n represent respectively the average number of acrylamide monomer units and CH 2 ═CH-Z monomer units in the polymer per 100 monomer units of the polymer, the sum of m + n totaling 100.", "Preferably n is about 50 to about 75 and m is 50-25.", "Particularly preferred terpolymers of the invention are solid crosslinked polymers comprising copolymerized acrylamide, acrylonitrile and a copolymerized ethylenically unsaturated carboxylic acid, ester or anhydride such as acrylic acid, itaconic acid, etc.", ", and the anhydrides and esters, thereof.", "Examples of suitable comonomers, one or more of which can be polymerized with acrylamide in accordance with the method of the invention, are the acrylates, and acrylate derivatives: piperazine, hydantion, cyclohexyl acrylate groups, and α-substituted acrylates wherein the α-substituent is alkyl such as methyl, ethyl, propyl and the like;", "aryl such as phenyl, naphthyl and the like;", "the ester moiety being alkyl such as methyl, ethyl, propyl and the like;", "aryl such as phenyl, naphthyl and the like;", "vinyl ethers, e.g. methyl, ethyl, propyl and higher alkyl;", "2-(N,N diethanol amino) ethyl acrylate, acrylamide, and substituted acrylamides e.g. methacrylamide, N-methylacrylamide, N,N-dimethylacrylamide;", "N-vinylacetamide, acrylic acid, acrylonitrile, allyl acetate, allyl alcohol, crotonic acid, dimethylaminoethylvinyl sulfide, diethylhexyl maleate, didodecyl maleate, fumaramide, itaconic acid, methacrylic acid, methoxystyrene, methyl vinyl ketone, 3-methyl-N-vinylpyrrolidone, 2-methyl-5-vinylpyridine, styrene, trichloroethylene, vinylcaprolactam, vinylcarbazole, vinylimidazole, vinyl laurate, vinyl benzimidazole, 1,3- and 1,4-butanediol monomethacrylate, vinyloxazolidinone, vinyl oxyethylurea, vinyl propionate, vinyl pyridine, vinyl stearate, vinyl acetate (and the derived vinyl alcohol,) diolpiperazine acrylate (or diacrylate) derivatives, hydantion acrylate or diacrylate, epoxy hydantion acrylates or other alkyl or aryl epoxy acrylate derivatives, Zn, Mg, Ca, Ba, Pb, Na acrylates or methacrylates.", "The homopolymers and interpolymers of the present invention may be crosslinked to provide tough, chemically stable, elastomeric products, highly insoluble in organic solvents, as well as in organic and inorganic acids and bases.", "The crosslinking agents that are suitably employed are those conventional crosslink agents containing two or more functional groups capable of taking part in the polymerization reaction so as to provide a polymeric material having a crosslinked three-dimensional structure.", "The crosslinking agent selected in any given case will generally depend upon the particular reactive groups on the polymeric chains to be crosslinked.", "Likewise, the concentration of crosslinking agent used will vary depending on the agent and the degree of crosslinking desired.", "In general, at least 2% up to 20% by weight based upon the monomers is employed.", "Accordingly, suitable crosslinking agents that have been found particularly applicable in the method of the invention are those having the structure: R (Q).", "sub.", "p wherein Q is selected from --OH, --SH, --Cl, --NCO, ##STR10## and ##STR11## where R and R'", "are polyvalent organic radicals of 2 to 12 carbon atoms.", "R and R'", "are preferably divalent or trivalent aliphatic or aromatic hydrocarbons.", "Illustrative of these crosslinking agents can be included ethylene glycol, propylene glycol, 1,2,3-propane triol, 1,2-ethane dithiol, 1,2,3-propane trithiol, 1,6-cyclohexane diol, 1,6-benzene diol, pentaerythritol, aryl, alkyl, hydantion diisocyanate derivatives, and other alkyl or aryl diisocyanate derivatives diethanolamine, triethanolamine, furan dianhydride, pyrazine dianhydride, pyromellitic dianhydride, urea, urine, melamine, melamine allyl derivatives, epihydrin alcohol, diacrylate derivatives, and the like.", "Advantageously, flame retardants are included in the polymerization reaction of the invention.", "The preferred types of flame retardants are those which bond chemically to the polymer so as to provide prolonged flame resistance to the polymeric material.", "Illustrative of such polymers are halogenated dienes such as hexachlorobutadiene, poly (phosphoramidopentachloro dienylurea), poly (phosphamidopentachlorodienylurea), poly (phosphorylnitrure) and halogenated unsaturated organic salts and esters such as 1,1-dichlorovinyl diethyl phosphate, bis (β-chloroethyl) vinyl phosphate, triethanolamino bisallyl chlorophosphoric acid and Phosgard C22R.", "In general flame retardants are added in amounts ranging from 0.5 to 25% by weight of the monomers.", "The polyimide homopolymers prepared by the invention range from viscous materials to solids depending upon their intended use and are characterized by average molecular weights of at least 1,000 up to 1,000,000 or more.", "In the interpolymers of the invention, the proportions of the various monomer units and their distribution along the carbon-carbon chain, and the length of the chain can vary over a wide range, thereby providing a family of polymers having different molecular weights and solubilities and differing in other important properties which render certain of these polymers particularly suited for specific applications.", "As in the case of the homopolymers the interpolymers range from viscous materials to high molecular weight solids.", "In instances where one or more of the monomers contain crosslinkable groups, a solid crosslinked product will generally result.", "Thus, while the composition and structure of the interpolymers can vary over wide ranges, nevertheless the interpolymers comprise about 30 to 90 mole %, preferably 50 to 85 mole % acrylamide and 70 to 10 mole %, preferably 50 to 15 mole % of at least one copolymerizable ethylenically unsaturated monomer.", "The polymerization of the monomer or monomers usually can be initiated at room temperature although some mild heating may be necessary in certain polymerization reactions.", "These reactions are exothermic and are accompanied by a release of heat causing an increase in reactant temperature.", "While normal temperature increases can be accomodated with no particular problem, too high of a rate for the exothermic polymerization reaction would cause a significant increase in temperature and "run away"", "polymerization.", "Thus, with most reactant systems it is preferred that the reaction temperature be conducted at about 20° to 60° C. If necessary, the reaction mixture may be cooled sufficiently to prevent excessive temperatures.", "The method of the invention can be carried out by simply mixing thoroughly as by homogenization at room temperature the reactants and catalysts.", "If desired a mutual solvent for the reactants and catalysts can be included.", "Suitable solvents are dimenthyl formamide, dimethyl sulfoxide, alkanols, dioxane and ketones.", "The materials are continually stirred until the solution begins to gel which is generally in about 1 - 3 1/2 hours.", "The gelling solution may then be case or poured into a desired form and the polymerization allowed to go to completion.", "As a preferred embodiment of the present invention there is included in the polymerization reaction a cocatalyst strong inorganic acid such as sulfuric acid or phosphoric acid and preferably a mixture of such acids.", "It has been found that the presence of the acids increases the efficiency of the catalyst system in that they convert all the oxalic groups to CO 2 .", "- and CO 2 thereby preventing conversion of the oxalic acid groups to oxalate salts.", "When employed the acids are added in concentrations of about 1 to 45 % by weight of monomer/catalyst.", "Optionally, and as another embodiment of the invention, the polymerization may be assisted by effecting the reaction in the presence of radiation such as ultraviolet light, gamma ray, electron beam and other forms of ionizing radiation.", "Often this radiation will be used in place of the persulfate component.", "When used, the dosage of ionizing radiation will fall in the range of 0.01 Megarads/hr to 10 Megarads/hr.", "According to one specific mode of preparing crosslinked polymeric compositions of the invention, a solution of one or more crosslinking agents such as urea in an acid such as phosphoric acid, sulfuric acid or mixtures thereof, is prepared.", "There is then prepared a separate solution of the monomer or monomers in a suitable solvent such as dimethyl sulfoxide, alkanol, water and the like, which solution is added to the acid solution with cooling.", "Any flame retardants, dispersing agents and filler materials may then be added.", "Lastly, yet a third solution of the oxalate complex catalyst alone or in combination with the alkaline persulfate in either a solvent which is also a solvent for the monomers or in one of the monomers is prepared.", "This third solution is added to the mixture of previous solutions and the resulting solution brought to reaction temperature.", "As aforementioned the polymerization is complete within about 3 1/2 hours, often within 1 or 2 hours.", "Upon completion of the polymerization reaction, a polymeric foam product either of the homopolymer or interpolymers of the invention may be prepared by simply heating the polymer in the presence of air at an elevated temperature, for example, to a temperature of at least 150° C, usually up to 300° C, preferably about 200° C to 250° C. The heating effects a breakdown in the oxalate complex to evolve CO 2 which becoming entrapped in the polymer forms a foamed product.", "The polymeric materials of the present invention have wide industrial application.", "In addition to the general fields of fiber, film and mold products, the foam products have excellent thermoisolation properties, very high flame resistance with a limiting oxygen index up to 95, very high chemical resistance and good physical properties in comparison with all organic foams and fibrous materials.", "The following examples are included to further illustrate the present invention but are not to be considered as limiting the invention in any respect.", "EXAMPLE I The following compounds (given by weight ratios) are homogenized at room temperature: ______________________________________Sulfuric/Phosphoric Acid (8/2 ratio) 25Urea Oxalate (or derivatives) 3Acrylamide (or derivatives) 12.5Hexachlorobutadiene 5.5Dimethylformamide/H.", "sub[.", "].2 O 1.5/0.5Zinc methacrylate 6.0Complex Oxalic (Compound 1) 0.082-(N,N diethanolamino) ethyl acrylate 3.5Potassium Persulfate 0.04Poly(phosphoramido pentachloro dienyl urea) 5.5______________________________________ These materials are stirred in an open container until a homogeneous solution is obtained and is continued to be stirred for an additional 120 minutes.", "When the solution begins to gel the solution is poured into a form and polymerization allowed to go to completion forming an elastomeric solid.", "Heating this solid to approximately 200° C in an oven or a tunnel (not requiring any special atmospheres) forms a fibrous foamed material in a few minutes.", "EXAMPLE II The process of Example I is repeated with the following composition: ______________________________________Sulfuric Acid (concentrated) 18or Phosphoric Acid (concentrated)Ureaperoxidate (or derivatives) 5Acrylamide (or derivatives) 13Dimethylformamide 3.3Furandianhydride (or other anhydrides) 1Hexachlorobutadiene 3.7Calcium methacrylate 7.52-Chloroethylchlorophosphate 1.5Poly(phospho amido penta chloro dienyl urea) 4.0Complex Oxalic (Compound 1) 0.01Potassium Persulfate 0.01______________________________________ EXAMPLE III The process of Example I is followed using the following compositions: ______________________________________H.", "sub[.", "].2 SO.", "sub[.", "].4 /H.", "sub[.", "].3 PO.", "sub[.", "].4 (4/1 ratio) 15Urea (or derivatives) 5Acrylamide (or derivatives) 50Dimethylformamide/H.", "sub[.", "].2 O (azeotrop mixture) 5Hexachlorobutadiene 3Triethanolaminobisdiallylchloro- phosphoric acid 2Complex Oxalic (Compound 2) 0.01K Persulfate 0.01Zinc acrylate 6.0______________________________________ EXAMPLE IV The process of Example I is followed with the following compositions: ______________________________________H.", "sub[.", "].2 SO.", "sub[.", "].4 /H.", "sub[.", "].3 PO.", "sub[.", "].4 (4/1 ratio) 3Urea (derivatives) 5Acrylamide (or derivatives) 10Dimethylformamide 1Epoxy -5,5 dimethylhydantion acrylate 7.7Acrylonitrile 1.5Barium methacrylate 8.2Poly(phosphorylnitrure) 5.5Hexachlorobutadiene 5Complex Oxalic (Compound 2) 0.01K Persulfate 0.01______________________________________ EXAMPLE V Example IV is repeated except that persulfate is not used but ultraviolet light in the range of 3000 to 7000 A or ionizing radiation of about 0.5 Megarads/hr is employed.", "The time of reaction is 5 to 12 minutes to form the polymer material.", "EXAMPLE VI The process of Example I is followed using the following compositions: ______________________________________Sulfuric Acid 10Phosphoric Acid 4Ureaperoxide 6Acrylamide 6Acrylonitrile 1Dimethylformamide 2Furandianhydride 0.1Hexachlorobutadiene 1Zinc methacrylate 4.8Complex Oxalic (Compound 1) 0.01Poly(phosphor amido penta chloro dienyl urea) 3.3Persulfate (K or NH.", "sub[.", "].4) 0.01______________________________________ EXAMPLE VII Example VI is repeated but substituting for the persulfate the radiation of Example V. EXAMPLE VIII Example VI is repeated with the addition of ______________________________________ Itaconic Acid 1 Sodium acrylate 3.5______________________________________ to the ingredients.", "EXAMPLE IX The process of Example I is followed with the compositions: ______________________________________Sulfuric Acid 18Urea/(Urea Oxalate) (1.0/0.3 ratio) 4Acrylamide 20Hexachlorobutadiene 4Ethanol 15Poly(phosphoryl nitrure) 7.5Complex Oxalic (Compound 2) 0.08K Acrylate 10.0K Persulfate 0.03______________________________________ EXAMPLE X Example IX is repeated substituting for the persulfate the radiation of Example V. EXAMPLE XI A. The process of Example I is repeated with the following compositions: ______________________________________Sulfuric/Phosphoric Acids (4/1 ratio) 10Acrylamide 8Urine 5Urea 2Zinc Acrylate 5.75Complex Oxalic (Compound 1) 0.08Poly(phospho amido penta chloro dienyl urea) 5.5Ammonium Persulfate 0.04______________________________________ This mixture will result in an elastomeric compound.", "B. The following addition may be made to the mixture in Example XI A.: ______________________________________K methacrylate 8.2Styrene/Acrylonitrile (3/1 ratio) 0.5 to 2______________________________________ This addition results in an improvement of the elastic properties of the material detailed in Example XI A. C. The following addition may be made to the materials listed in Example XI A.: ______________________________________Isoprene 0.5 to 3Dimethylformamide 1 to 3______________________________________ D. The following addition may be made to the materials in Example XI A.: ______________________________________Dianhydride (furan, pyrazine,pyromellitic or other anhydrides) 0.01 to 0.1Dimethylformamide 1 to 7______________________________________ The resultant elastomer will have improved mechanical strength compared to the material listed in Example XI A. EXAMPLE XII The process of Example I is followed with the following compositions: ______________________________________Sulfuric Acid 20Phosphoric Acid 10Urea 10Acrylamide 30Acrylonitrile 6Styrene 6Zinc acrylate 6.8Dimethylformamide 4Poly(phosphor amido pentachloro dienyl urea) 2.5Hexachlorobutadiene 5______________________________________ EXAMPLE XIII The materials in Example XII are mixed with metal or metal oxides (aluminum, alumina, copper or others), glass or glass binder, in the following ratios: 0.5 to 2.5 part by weight of metal, metal oxide or glass and 5 to 15 parts by weight of polymer solution.", "These additions improve the physical properties of the material.", "EXAMPLE XIV To 43 units of phosphoric acid gradually is added 45 units of urea, while the mixture is stirred constantly.", "To decrease the viscosity of the solution the temperature is increased to about 30° C. When the urea is completely dissolved, there is added another dimethylsulfoxide solution containing: ______________________________________Acrylamide 180Zinc methacrylate 25Acrylonitrile 53Poly(phosphoryl nitrure) 10Methylmethacrylate 40______________________________________ Continuous stirring is maintained.", "Using another 9 to 14 units of methylmethacrylate 0.5 to 1.5 units of compound 1 is brought to a solution.", "This solution is then added to the previous mixture.", "The temperature is raised to 40° C;", "meanwhile the solution is stirred constantly.", "The solution will gel after some time, at which the stirring is stopped.", "After the material has fully polymerized, it is foamed at about 200° C. EXAMPLE XV The previous example is repeated with the addition to the phosphoric acid solution of 0.5% by weight of hexachlorobutadiene based on the monomers and 1.2% by weight melamine based on the urea.", "The resultant polymer is foamed at 190° C. All the crosslinked polymeric products produced by Examples I through XV are fibrous materials thermostable to 150° C and flame resistant.", "When the fibrous material is held in a Bunsen burner flame (over 95% oxygen), the fibrous material carbonizes directly without flaming or developing much smoke, and when removed from the flame, the material does not flame and does not burn.", "The polymeric products when subjected to chemical solubility tests for 216 hours at room temperature were found not soluble in the following chemicals: water, aqueous alkaline solution (n/10 NaOH), sulfuric acid (conc.", "98%), formic acid (conc.", "90.3%), phosphoric acid (conc.), acetic acid (conc.), oxidant mixture K 2 Cr 2 O 7 -H 2 SO 4 conc.), acetic anhydride, benzene, aromatic hydrocarbons (gasoline), cyclohexanone, chlorobenzene, tetrahydrofuran (THF), methanol, hexane, dichloromethane, methylenechloride, ethylene chloro bromide, pyridine, dimethylformamide, dimethylsulfoxide, ammonium hydroxide (conc.", "28.9%).", "The specific gravity of the products falls in the range of approximately 0.018 to 0.5 and the products exhibit no liquid absorption.", "Further, the products are characterized by a relative humidity of 2.5 - 3.5% (no static electricity build-up) and high thermal expansion and shock absorption properties." ]
The Sequence Listing submitted in text format (.txt) filed on Nov. 26, 2013, named “SequenceListing.txt”, created on Nov. 25, 2013, 11.1 KB), is incorporated herein by reference. TECHNOLOGICAL FIELD This invention generally relates to biomolecular electronics, to an electronic device for communication with living cells and methods of use. BACKGROUND One of the major challenges in the use of multi-microelectrode arrays (MEA) in recording (in vitro and in vivo) neuronal network activities is the very low signal to noise ratio. This limits the monitoring to field potentials (˜100 μV) generated by action potentials and precludes the detection of sub-threshold synaptic potentials. Consequently, large efforts are devoted to the development of nanotechnologies to better couple excitable cells to electronic devices. Currently, extracellular MEA is the only available technique for high temporal resolution for multi unit electrical recordings and stimulation. However, although this technique reflects synchronized sub threshold activity generated by ensembles of nearby neurons, it does not provide direct information on synaptic potential. On the other hand, sharp intracellular microelectrodes and patch-electrodes enable to resolve sub-threshold events with an excellent signal to noise ratio. However, the use of such electrodes is limited to a relatively small number of neurons. In addition, the duration of recordings and stimulation is limited. International application nos. WO2004/109282 [1] and WO2008/111047 [2] show that, in cultured non-vertebrate organism, Aplysia , by using an array of chemically functionalized electrodes, it is possible to obtain intracellular recordings of neuronal action potential and sub-threshold synaptic potentials. The biological processes enabling these recordings are in line with the observations that the electrodes were engulfed by the Aplysia's neurons and a high seal resistance was generated between the neuron and the electrode and finally that unexpected junctions were formed in the neuron-electrode interface supporting a bidirectional electrical coupling. Thus, an increased conductance of the membrane was observed. REFERENCES [1] WO2004/109282 [2] WO2008/111047 [3] WO2002/070647 [4] WO2004/022697 [5] WO2007007325 [6] WO2011/027342 [7] Spira, M. E. et al., Use of Aplysia neurons for the study of cellular alterations and the resealing of transected axons in vitro. J. Neurosci Methods 69, 91-102 (1996). [8] Ziv, N. E. et al., Induction of growth cone formation by transient and localized increases of intracellular proteolytic activity. J. Cell Biol. 140, 223-32 (1998). [9] Wang, W. et al., Crystallization and preliminary X-ray crystallographic analysis of SP1, a novel chaperone-like protein. Acta Crystallogr D Biol Crystallogr 59, 512-4 (2003). [10] Wang, W. X. et al., Aspen SP1, an exceptional thermal, protease and detergent-resistant self-assembled nano-particle. Biotechnol. Bioeng. 95, 161-8 (2006). [11] Medalsy, I. et al., SP1 protein-based nanostructures and arrays. Nano Lett. 8, 473-7 (2008). [12] Malkinson, G. et al., Calcium concentration threshold and translocation kinetics of EGFP-DOC2B expressed in cultured Aplysia neurons. Cell Calcium 39, 85-93 (2006). [13] Khoutorsky, A. et al., Calpain inhibitors alter the excitable membrane properties of cultured Aplysia neurons. J. Neurophysiol 100, 2784-93 (2008). GENERAL DESCRIPTION The present invention is based on findings by the inventors that ring-like non-membrane polypeptides spontaneously partition (integrate, intercalate, embed) into cell membranes. These ring-like polypeptides orient in the membrane such that they form nanopores within the membrane and subsequently modulate the membrane's properties. The degree of partitioning and generation of the nanopores may be controlled by predefining the number of ring-like non-membrane polypeptides to be integrated in the membrane. The nanopores may be made partially or fully closed, for example, by placing in the nanopores “plugs” in the form of nanoparticles, such as gold nanoparticles. Interestingly, formation of nanopores in the membrane of an electrically active cell or a cell having physiological response to electric stimulation may provide neuroelectronic interface that may assist in intracellular recordings and stimulation of many such individual cells. Thus, the invention disclosed herein has the advantage of permitting to control and fine-tune the recording and/or stimulation of a desired cell by controlling the extent of nanopore formation. Specially, the inventors have found that ring-like polypeptides, such as SP1 and derivatives thereof, which are absent from natural animal cell membranes, form nanopores in membranes of living animals cells and increase the membrane conductance. The integration of such a ring-like polypeptide may be substantially irreversible. However, as demonstrated herein, it is possible to reverse the effect induced by such ring-like polypeptides, as SP1 polypeptide, or a derivative thereof such as 6His-SP1, on the membrane conductance, by addition of, e.g., gold nanoparticles (GNP), as explained hereinabove, either prior to or after the partition of the polypeptides into the membrane. Therefore, in accordance with a first aspect, the present invention provides a biological membrane comprising at least one ring-like polypeptide, wherein the at least one ring-like polypeptide is not a membrane protein (or is not a membrane protein naturally associated with said biological membrane). The “ring-like polypeptide” is an oligomeric polypeptide (protein) arranged in a circular ring shape (ring-like), namely having a central cavity (as inner pore or inner hole) and having an outer radius defining the outer rim of the ring-like structure and an inner radius defining the radius of the cavity. The polypeptide may comprise several monomeric subunits, being either identical (homo) or different (hetero) from each other, together having a ring-like structure, e.g., complex polypeptides. The polypeptide may be a native homo-oligomer or hetero-oligomer comprising monomeric subunits arranged, for example, in a concentric arrangement. As disclosed herein, the ring-like polypeptide partitioned (integrated, intercalated) in the cell membrane, in accordance with the invention, is a “non-membrane polypeptide” naturally not found in animal cell membranes, e.g., in human cell membranes, under physiological conditions (extracellular or intracellular conditions that may occur in nature for that organism or cell system, in contrast to artificial conditions possibly in a laboratory). In other words, the ring-like polypeptide is not naturally located in the plasma membrane or any membrane of a living animal cell. In some embodiments, the ring-like polypeptide used in accordance with the invention is a heat shock protein (HSP), a functionally related protein involved in the folding and unfolding of other proteins. The expression of HSP is increased when cells are exposed to elevated temperatures and other stress. According to some embodiments, the ring-like polypeptide is HSP 60, HSP 70, HSP90. According to some embodiments, the ring-like polypeptide is thermolysin. In other embodiments, the ring-like polypeptide is a boiling stable polypeptide, having a structural oligomeric stability following treatment at about 95° C., in an aqueous solution, for at least 10 minutes, as determined by a size fractionation assay. In further embodiments, the ring-like polypeptide is a denaturant-stable polypeptide, having a structural oligomeric stability of an oligomeric protein following treatment in aqueous solution containing 1:2,000 molar ratio (monomer:SDS), as determined by a size fractionation assay. Still according to some embodiments, the ring-like polypeptide is a stable protein variant. In some embodiments, the ring-like polypeptide is stable protein 1 (SP1) polypeptide [3-5]. The preparation, structural modification (mutations) and characteristics of SP1 are disclosed in international patent application nos. WO2002/070647 [3], WO2004/022697 [4], WO2007/007325 [5] and WO2011/027342 [6], and corresponding US patent applications, each being incorporated herein by reference. SP1 is a homo-dodecamer oligomeric protein, with an outer diameter of 11 nm and an inner diameter of 3 nm. SP1 is naturally localized in the cytoplasm of plant cells and is not found in animal, e.g., mammalian (human or non-human) cells. In some embodiments, the SP1 polypeptide is the wild type polypeptide (disclosed, for example, in [6] as SEQ ID NO: 4) or any derivatives thereof (disclosed, for example, in any of references [3-6], each being incorporated herein by reference). The term “derivatives thereof” is used herein to denote any genetically modified variant of wild type SP1 including fragments thereof, homologous thereof or mutations thereof. Modifications of the SP1 polypeptide may enhance the protein functionality, for example, in interaction with a surface, as disclosed hereinbelow. As appreciated by those versed in the art, genetic modification of a polypeptide is of common practice and includes mutations in the polynucleotide encoding the respective polypeptide, such that a selective mutation in the nucleotide sequence would result in a desired amino acid mutation. Any mutation of the SP1 polypeptide referred to herein is a mutation based on the wild-type polypeptide. Mutations in the polypeptide may include substitutions (mutations) of at least one amino acid, deletion of at least one amino acid or addition of at least one amino acid. Thus, the polypeptide used in accordance with the present invention may be selected from the wild-type SP1 polypeptide, cysteine mutated/substituted/added SP1 polypeptide, and histidine mutated/substituted/added SP1 polypeptide. In some embodiments, the SP1 polypeptide is wild-type SP1 polypeptide (SEQ ID NO:1). In some embodiments, the SP1 polypeptide is a polypeptide encoded by the polynucleotide deposited in NCBI under GenBank: AJ276517.1 (SEQ ID NO:8). In other embodiments, the SP1 polypeptide comprises additional histidine residues (SEQ ID NO:2) and encoded by the polynucleotide having the sequence SEQ ID NO:9. The 6His-SP1 derivative describes herein corresponds to SEQ ID NO:2. In further embodiments, the SP1 polypeptide is a homologous variant to wild type SP1. The homologous variant may comprise for example deletion of amino acids in the N-terminal region of the wild type SP1. In some embodiments, the SP1 polypeptide is a variant polypeptide with a deletion of amino acids in the N-terminal region. This variant SP1 polypeptide having SEQ ID NO:3, being encoded by the polynucleotide having the sequence SEQ ID NO:10. In some embodiments, the SP1 polypeptide comprises mutations of amino acids to cysteine. Non-limiting examples for such a cysteine-mutated SP1 polypeptides include SEQ ID NO:4 (encoded by the polynucleotide having the sequence SEQ ID NO:11); SEQ ID NO:5 (encoded by the polynucleotide having the sequence SEQ ID NO:12); SEQ ID NO:6 (encoded by the polynucleotide having the sequence SEQ ID NO:13); and SEQ ID NO:7 (encoded by the polynucleotide having the sequence SEQ ID NO:14). As described throughout, the non-membrane polypeptides spontaneously partition in the plasma membrane of living animal cells and modulate their properties; the biological membrane thus being regarded as a modified membrane. The “biological membrane” in which the polypeptide, e.g., SP1, is integrated, may be any membrane having at least a bilayer of lipid molecules. The biological membrane is, in some embodiments, a natural membrane, such as a cell membrane (plasma membrane) which includes proteins embedded within the lipid bilayer and which separates the interior of cells from the outside environment. In some embodiments, the cell of which membrane is modified, in accordance with the invention, is an animal cell. In some embodiments, the cell is from a vertebrate or non-vertebrate organism. In some embodiments, the cell is a mammalian cell. In some embodiments, the cell is a human cell or non human cell. In some embodiments, the cell is selected from a neuron, a muscle cell, a cell of a secreting gland and others. In some embodiments, the cell is a human cell selected from a neuron, a muscle cell, a cell of a secreting gland and others. In some embodiments, the biological membrane is not one which does not comprise any characteristics of a plasma membrane (for example lipids and proteins). In some embodiments, the biological membrane may be an artificial biological membrane model, such as liposomal membrane, composed of a lipid bilayer. It should be appreciated that upon integration of the polypeptide, e.g., SP1 into the cell membrane, the polypeptide adopts a spatial orientation with respect to the lipid bilayer. Without wishing to be bound by theory, it is believed that the polypeptide is oriented in the membrane such that transfer of materials through the polypeptide inner pore is enabled, thus constituting after intercalation, the nanopores in the cell membrane. The terms “nanopore” and “nanochannel” denote the pores (holes) in the membrane. In some embodiments, each of the nanopores has, on average, a diameter of up to about 10 nm; in other embodiments, up to about 3 nm; and in further embodiments, up to 2.5 nm. In some embodiments, the polypeptide nanopore is associated with a metal nanoparticle, said nanoparticle, when present in the nanopore, acting as a plug which closes the nanopore from material transfer therethrough. The “nanoparticle” may be of any metal or an alloy of metals. Non-limiting examples of such metals are gold, platinum, silver, iron, copper, nickel, palladium, iridium, and titanium. In some embodiments, the size of the nanoparticle is from about 1 nm to about 10 nm; in other embodiments, from about 1 nm to about 5 nm; and in further embodiments, from about 1 nm to about 3 nm. In some embodiments, the nanoparticle is a gold nanoparticle. In further embodiments, the polypeptide is SP1 [SEQ ID NO:1], SP1 variant [SEQ ID NO:3] or 6His-SP1 [SEQ ID NO:2]. Thus, the invention provides a biological membrane (modified membrane) comprising SP1 [SEQ ID NO:1] or 6His-SP1 polypeptide [SEQ ID NO: 2], wherein the inner pore of said polypeptide being occupied a gold nanoparticle. In some embodiments, the modified membrane in which the polypeptide, e.g., SP1 or 6His-SP1 is integrated (whether or not the polypeptide is associated with a metal nanoparticle) may be associated with a surface. The surface may have any predefined geometry that may be a stand-alone construct being used to minimize any possible movement of the membrane and may be composed of a metallic material or coated with such a material. The metal may be any metallic element, compound or alloy that is electrically conductive. In some embodiments, the surface is a metallic surface or coated with a metallic layer rendering it conductive. In some embodiments, the surface is of a material selected from gold, platinum, silver, nickel, palladium and silicon. The association with the surface may be through one or more linking groups, which act to link the surface with the polypeptide moiety integrated in said membrane and/or with a region of the cell membrane which is not a region defined by the integrated polypeptide. The association of the surface with the polypeptide residue, or with other regions of the membrane may be via a pendent (native or modified) bifunctional moiety capable of association with the surface (via one functional group of the bifunctional moiety) and with the polypeptide/membrane (via the same or different group of the bifunctional moiety). The surface binding moiety may be selected from a thiol, a carboxylic acid (or a carboxylate), an amine, an amide, an alcohol (or an alkoxy), a siloxy, and others. The polypeptide/membrane binding moiety may be selected from a thiol, a carboxylic acid (or a carboxylate), an amine, an amide, an alcohol (or an alkoxy), and others. In some embodiments, the bifunctional moiety is selected from homo-bifunctional linkers and hetero-bifunctional linkers. In some embodiments, the homo-bifunctional linker, having the same type of group at either end, may be selected from, for example, glutaraldehyde, bis(imidoesters) and bis(succinimidylesters) (also known as NHS esters). In some embodiments, the hetero-bifunctional linkers, having different type of binding groups, may be selected from, for example, [succinimidyl 3-(2-pyridyldithio)propionate] (SPDP), [succinimidyl trans-4-(maleimidylmethyl)cyclohexane-1-carboxylate] (SMCC) and Succinimidyl-4-(p-maleimidophenyl)butyrate (SMPB). In some embodiments, the surface and polypeptide/membrane binding moieties are bonded to each other through a linking moiety which may be a straight chain or branched chain organic group, such as a C1-C20 alkylene group. In some embodiments, the linking moiety is a C1-C4 alkylene group. In some embodiments, the association of the surface with the polypeptide/membrane is via one or more (plurality) amino acid groups, non-limitedly selected from glycine, alanine, histidine, cysteine and methionine residues. As indicated herein, the amino acid may be a pendant group on the polypeptide/membrane structure or a moiety (amino acid) of the polypeptide sequence. In some embodiments, said amino acid is cysteine. In some embodiments, the association is via a polymer, a peptide, a carbohydrate, a lipid, or a nucleic acid. The association with the surface may be by a variety of chemical and/or physical interactions, such as covalent bonding, hydrogen bonding, electrostatic interaction, complexation, van der Walls interaction and ionic interaction. In some embodiments, the interaction is covalent bonding. The surface, with which the modified membrane of the invention is associated, may be a surface region of at least one element of a device, e.g., an electronic or optical device, e.g., for recording or stimulating a tissue. In some embodiment, the device is an electronic device. In other embodiments, the surface region is an electrode surface region. In further embodiments, the surface is a surface region of a cell-communicating component of an electrode; the component being adapted for sensing and/or stimulating a cell activity. In some embodiments, the surface may be at least a surface region of an electrode. Thus, the invention provides an electrode being associated on at least a region of its surface with a biological membrane comprising at least one ring-like polypeptide. In some embodiments, the at least one ring-like polypeptide is not a membrane protein. In other embodiments, the polypeptide is SP1 [SEQ ID NO: 1], a variant of SP1 [SEQ ID NO:3] or cysteine-mutated variants of SP1 having for example [SEQ ID NO:4], [SEQ ID NO:5], [SEQ ID NO:6] or [SEQ ID NO:7]. In further embodiments, the biological membrane is a membrane of a living animal cell. As used herein, the electrode of the invention is associated with a current source and configured to apply current to a tissue, ex vivo or in vivo. The electrode may be any one of a gold electrode, a platinum electrode, a carbon electrode, a silver electrode, a nickel electrode, or a palladium electrode. The electrode may be a regular electrode or a gate electrode. In some embodiments, the gate electrode may be an ion sensitive gate. The ion-sensitive material may be Aluminum Oxide (Al 2 O 3 ), Silicon Nitride (Si 3 N 4 ), Indium Tin Oxide (In 2 O 3 —Sn 2 O 3 ), Silicon Oxide (SiO 2 ) or Tantalum Oxide (Ta 2 O 5 ). In some embodiments, the electrode is an electrode intended to communicate with cells having electric properties, or having physiological responses to electrical stimulation, such as neurons, muscle cells, and cells of secreting glands. The electrode may be part of an electrode assembly. In some embodiments, said electrode assembly comprises a pair of source-drain electrodes. In other embodiments, said assembly comprises at least a pair of source-drain electrodes and at least one gate electrode. As appreciated, the invention permits utilization of ring-like polypeptides, such as SP1 or its various derivatives, to electrically and chemically couple sensing pads of electronic devices (transistors gates or passive electrodes) and living cells. This clearly facilitates assembly of neuroelectronic hybrid systems or generate chemical and electrical coupling in vitro or in vivo. Electrical communication between an electrode according to the present invention and a cell may achieve one or more of: 1. Detection and recording of the presence of current in cells by the electrode or detection of a current change; 2. Detection and recording of changes in potential on plasma membrane of cells or changes in said potential; 3. Providing current to cells; and 4. Applying an electric field to cells. The cell which membrane is modified by a polypeptide in accordance with the invention may be a cell ex vivo or in vivo. For some applications, particularly such which require stimulation or recording of cells in vivo, the construction of a modified cell membrane onto, e.g., an electrode surface may be achieved by first associating the polypeptide to said surface and subsequently permitting integration of the polypeptide into a cell membrane in vivo. Thus, according to another aspect, the present invention provides a surface, e.g., an electrode surface, for adherence of cells thereto, at least a region of the surface being in association with at least one (plurality of) ring-like polypeptide capable of (adapted for, for use in, for permitting) integration into a cell membrane (upon contact therewith and under physiological conditions), said ring like polypeptide not being a membrane protein. Association between the surface region and the polypeptide is as disclosed hereinabove. As defined above, the surface may have a predefined geometry, optionally comprising at least one curved structure. The curved structure may be an elliptical structure or generally a micronail structure having a micrometer or nanometer scale contact region with the membrane surface. The “micronail”, in the context of the present invention, is a micrometer or nanometer scale protrusion from the surface. The surface may comprise one or more such micronail structures, which may be identical to each other in their chemical properties, shape and size or which differ from each other in at least one of chemical properties, shape and size. Each of the micronails acting as individual spaced apart electrodes, distributed to optimize engulfment/wrapping/internalization by a cell membrane. The interaction between the surface and the cells membrane, i.e., engulfment/wrapping/internalization, may comprise wrapping (engulfment) of the cells membranes around the surface without disturbing the integrity of the membrane. The surface is defined as having cellular-engulfing promoting properties, resulting from the morphology and dimensions of the surface, and/or from the inherent physical and chemical properties of the surface material from which it is formed (such as metal selected from gold, copper, aluminum, platinum, silver, alloys of these metals or combinations thereof) or which is coated with. The surface may be coated by molecules that recognize plasma membrane components, such molecules may be selected from a protein, a lipid, a polysaccharide, a glycoprotein, and others. Examples of such molecules are ligand of plasma membrane receptors (or receptor binding parts of said ligand), receptors that recognize plasma membrane components; lectins that bind to plasma membrane glycoproteins; antibodies that recognize plasma membrane components (either proteins or non-proteins) or binding fragments of said antibodies; integrins that recognize short linear amino acids present in extracellular proteins, or a combination of two or more of these proteins. The structure, dimensions and density of the surface can be optimized to maximize the electrical and chemical coupling between the hybrid components, namely the transistor and the living cell. In accordance with this aspect of the invention, at least a region of the surface, e.g., electrode surface, is wrapped by the cell (via a mechanism know as phagocytosis/pinocytosis or endocytosis) and in view of the integration of the polypeptide into the cells' membrane, the existing membrane nanopores allow part of the surface to pass through the plasma membrane into (or become in contact, or interact with) the cytoplasm and allow the membrane to close around the surface, forming a giga-seal between the plasma membrane and the surface. The passing of the surface inside the cells' cytoplasm allows sensing and recording at least one of electrical and chemical events inside the cells, as well as electrical stimulation from inside the cells. According to some embodiments, the present invention provides a metallic surface, e.g., an electrode, wherein at least a region of the surface is associated with a membrane integrated with at least one SP1 polypeptide or any derivative thereof. In accordance with yet another aspect, the present invention provides a device comprising an electrode arrangement having at least one electrode, wherein at least a region of a surface of the electrode being associated with a modified membrane, as described herein. In accordance with yet a further aspect, there is provided a device for interaction with a cell, the device comprising an electrode which at least a region of its surface being associated with a modified membrane according to the invention, the interaction being via non-membrane ring-like polypeptides present on the cell membrane, said interaction permitting at least one of a chemical and electrical interaction between the electrode surface and the cell cytoplasm. In accordance with yet a further aspect, there is provided a device for interaction with a cell, the device comprising an electrode which surface being capable of association with a cell cytoplasm, wherein said surface being associated with at least one non-membrane ring-like polypeptide, said polypeptide being capable of undergoing intercalation into a cell membrane for permitting at least one of a chemical and electrical interaction between the electrode surface and the cell cytoplasm. Electrical communication using such an electrode or an electric device may be carried out for a variety of purposes ranging from basic research to diagnostic means and biomedical devices being used in numerous cells and tissues. The tissue cells may be any type of cell of interest, especially for electrical recording/stimulating purposes, the cells are typically (but not exclusively) excitable cells such as neurons, muscles endocrine cells and others (of any species). The increased conductance observed in the membranes comprising the at least one ring like polypeptide may be used in a variety of experimental technologies such as recording of low signal to noise ratio neuronal network activity in cells and hence to obtain a better understanding of the neural network. Further, the device may be used in multielectrode array (MEA). The device described throughout may be used for diagnostic. Further, the electronic device according to the present disclosure may be used for the construction of biomedical devices; especially those which need a functional link between nerves or muscles to electric components. Thus, in accordance with yet another aspect, the present invention provides a biomedical device, said device comprising an electrode which surface being capable of association with a tissue cell cytoplasm, wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into a cell membrane of said tissue, for permitting at least one of a chemical and electrical interaction between the electrode surface and the cell cytoplasm. In some embodiments, the biomedical device may be prosthesis (also termed prosthetic), namely an artificial device extension that replaces a missing body part by using mechanical devices with human muscle, skeleton or a system to assist or enhance motor control lost by trauma, disease or defect by functionally linking between the cells and the electronic sensing and recording device as described herein. An electrode or the device according to the invention may be used, for example, to electrically record cell, e.g., neuronal activity (neuronal signals) in a tissue, ex vivo or in vivo e.g., the brain. This recording may be used to restore mobility or assist in controlling devices. Thus, the invention also provides a recording device, said device comprising an electrode which surface being capable of association with neuronal cells, wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into a cell membrane of said neuron, for permitting at least one of a chemical and electrical interaction between the electrode surface and the neuronal cells. In some embodiments, the device is used for recording neuronal activity (signal) in vivo, e.g., in the brain to improve, increase or induce mobility or neural stimulation of a body part. In some embodiments, the biomedical device is an implant. An electrode or the device according to the invention may be used, for example, as a retinal implant (an intraocular prosthetic device), by electrically stimulating retinal cells. In addition, it may be used as a cochlear implant that is an implanted surgical device that provides a sense of sound. Thus, the invention also provides a retinal implant, said implant comprising a electrode which surface being capable of association with cells of a tissue region of the retina, wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into a cell membrane of said retina, for permitting at least one of a chemical and electrical interaction between the electrode surface and the retina cells. In some embodiments, the retinal implant is used for stimulating nerve cells in the retina to induce, improve or increase light sensitivity (and subsequently vision). The invention further provides an ear implant (e.g., cochlear implant), said implant comprising a electrode which surface being capable of association with cells of a tissue region of the ear (e.g., the inner ear), wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into a cell membrane of said ear region, for permitting at least one of a chemical and electrical interaction between the electrode surface and the ear tissue cells. In some embodiments, the ear implant is used for stimulating nerve cells in the ear tissues to induce, improve or increase sensitivity to sound (and subsequently hearing). The invention further provides a method for electrically stimulating cells of a tissue region, said method comprising: positioning adjacently to a tissue region a device comprising an electrode which surface being capable of association with cells of said tissue region, wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into cell membranes of cells present in said tissue region, permitting internalization/engulfing/wrapping of said cell membranes around said electrode surface and intercalation of said at least one non-membrane ring-like polypeptide in said cell membrane; and electrically stimulating said cells in said tissue region. In some embodiments, the stimulation is in vivo. In some embodiments, said tissue to be stimulated in accordance with the method of the invention, is a tissue of the eye or the ear. In further embodiments, said cells are selected from a neuron, a muscle cell, a cell of a secreting gland, and others. The invention further provides a method for electrically recording cells of a tissue region, said method comprising: positioning adjacently to a tissue region a device comprising an electrode which surface being capable of association with cells of said tissue region, wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into cell membranes of cells present in said tissue region, permitting internalization/engulfing/wrapping of said cell membranes around said electrode surface and intercalation of said at least one non-membrane ring-like polypeptide in said cell membrane; and electrically recording activity of said cells in said tissue region. In some embodiments, the recording is of a tissue activity in vivo. In some embodiments, said tissue to be recorded in accordance with the method of the invention, is a brain tissue. In further embodiments, said cells are neuronal cells. In accordance with another aspect, the present invention provides a process for the preparation of a modified biological membrane, according to the present invention, the process comprising: proving a biological membrane in a growth medium; adding an amount of a ring-like polypeptide to the growth medium, wherein said polypeptide is not a membrane polypeptide; and allowing said polypeptide to integrate into said membrane and forming nanopores in said membrane thereby resulting in a modified biological membrane. The term “growth medium” denotes a liquid or gel designed to support the growth of biological membranes. In some embodiments, the biological membrane is a cell membrane and thus the term growth medium denotes a culture medium. The growth medium may comprise, for example, source of amino acids, sugars, antibiotics. In some embodiments, the biological membrane is an artificial membrane, thus the growth medium is regarded as a medium allowing the stability of the artificial membrane within. In accordance with this aspect, the amount of ring like polypeptide to be added to the growth medium may be determined a priory in order to allow the control on the amount of nanopores formed within the membrane. BRIEF DESCRIPTION OF THE DRAWINGS In order to understand the disclosure and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: FIGS. 1A-1E are graphs showing that wtSP1 induces membrane depolarization and decreased input resistance. FIG. 1A shows voltage drop in response to a constant rectangular current pulse injected into the neuron; FIG. 1B is a graph showing the relations between Rin and the transmembrane potential; FIG. 1C is a graph showing the effects of wtSP1 on the transmembrane potential and Rin; FIG. 1D is a graph showing the rate of SP1-induced membrane depolarization, SP1 application is indicated by an arrow; FIG. 1E is a graph showing the effects of wtSP1 washing on membrane potential, the onset of the wash is indicated by the dashed line. FIGS. 2A-2H are graphs showing the reversible conductance blockade of the 6HIS-SP1 inner pore by gold nanoparticles. FIG. 2A is a graph showing the effect of 6His-SP1 on the transmembrane potential and Rin; FIG. 2B is a graph showing the dynamics of 6His-SP1-induced membrane depolarization; FIG. 2C is a graph showing the membrane potential and input resistance of a single neuron before and after the application of 2 μM 6His-SP1-GNP complex; FIG. 2D is a graph showing the resting potential after the application of 6His-SP1-GNP complex; FIGS. 2E and 2F are graphs showing effect of application of GNPs to the bathing solution after the onset of 6His-SP1-induced effects on the transmembrane potential and Rin ( FIG. 2E ) and membrane depolarization ( FIG. 2F ); FIGS. 2G and 2H are graphs showing the effects of application of GNPs to the bathing solution after the onset of wtSP1-induced effects on the transmembrane potential and Rin ( FIG. 2G ) and membrane depolarization ( FIG. 2H ). FIG. 3 is a schematic representation showing the attachment of an SP1 derivative to the plasma membrane and the blocking of the SP1 conducting pore by a nano-gold particle. FIG. 4 depicts the SP1 nucleotide sequence (SEQ ID NO:8) and the deduced (encoded) SP1 protein sequence (SEQ ID NO:1). FIG. 5 depicts a nucleotide sequence (SEQ ID NO:9) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:2). FIG. 6 depicts a nucleotide sequence (SEQ ID NO:10) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:3). FIG. 7 depicts a nucleotide sequence (SEQ ID NO:11) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:4). FIG. 8 depicts a nucleotide sequence (SEQ ID NO:12) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:5). FIG. 9 depicts a nucleotide sequence (SEQ ID NO:13) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:6). FIG. 10 depicts a nucleotide sequence (SEQ ID NO:14) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:7). DETAILED DESCRIPTION OF EMBODIMENTS Materials and Methods Neurons Culture Left upper quadrant neurons (LUQ) from the abdominal ganglion of juvenile Aplysia (2-5 g) were cultured, as previously described [7, 8]. Briefly, animals were anesthetized by injection of isotonic MgCl 2 solution. The ganglia were isolated and incubated for 1.5-3 h in 1% protease (Type IX, Sigma) at 34° C. The ganglia were then de-sheathed, and the cell bodies or their neurons with their long axons were pulled out with sharp micropipets and placed on poly-L-lysine coated (Sigma) glass bottom culture dishes. The culture medium consisted of 10% filtered hemolymph from Aplysia faciata collected along the Mediterranean coast, and L-15 (Gibco-BRL) supplemented for marine species. Twenty-four hours after plating dishes were transferred to an 18° C. incubator. Experiments were preformed 3-5 days after plating. Electrophysiology All experiments were performed at room temperature in artificial sea water (ASW) composed of NaCl 460 mM, KCL 10 mM, CaCl 2 10 mM, MgCl 2 55 mM and HEPES [N-(2-hydroxyethyl)-piperazine-N′-2-ethanesulfonic acid, Sigma] 11 mM, adjusted at pH 7.6. Recording and stimulation of LUQ neurons were conducted in current-clamp mode using sharp 5-10 MΩ glass microelectrodes filled with 2M KCl. The microelectrode served for both current injection and voltage recording (Axoclamp-2A; Axon Instruments). Signals were digitally recorded by means of a Digidata 1322A interface (Axon Instruments, Union City, Calif.) and analyzed with Clampfit software (Axon Instruments). SP1 and 6His-SP1 Expression and purification of all SP1 mutants were performed as described previously, wild-type SP1 (wtSP1) [9, 10] and 6His-SP1 [11]. SP1 and 6His-SP1 were applied to the bathing solution in ASW to generate a final concentration of 2 μM. Ca Imaging Calcium imaging was conducted as previously reported [12]. Briefly, the system used for confocal calcium imaging consisted of an Olympus microscope IX70 and a Bio-Rad (Hercules, Calif.) Radiance 2000/AGR-3 confocal imaging system. The objective used was an Olympus planApo 60×1.4 NA oil objective. The images were collected and processed using LaserSharp and LaserPix BioRad software, respectively. For the experiments, fluo-4 10 mM (pentapotassium salt, Invitrogen) in 0.5 KCl was pressure microinjected into the neurons. Imaging was preformed after the dye has equilibrated throughout the main axon and the small neuritis (approximately 30 minutes after the injection). Fluo-4 was excited with 488 nm (Argon laser), and the emission was collected at 500-560 nm. EXAMPLE 1 Partition of wtSP1 into Plasma Membrane The purpose of this experiment was to examine if wtSP1, dispersed in a physiological solution, spontaneously partition into the bi-lipid membrane of living neurons and form nanopores. Methods The culture medium, which contains Aplysia hemolymph, was replaced by artificial sea water (ASW), an ionic solution. A cultured neuron was then impaled by a sharp glass microelectrode that served for both current injections and voltage recordings [13]. Results The input resistance (Rin) of the neuron was calculated from the transmembrane voltage drop generated by small intracellular hyperpolarizing rectangular 0.3 nA current pulses lasting 2 s ( FIG. 1 ). The relations between the transmembrane potential and the neuron's input resistance were determined in control experiments by intracellular injection of the hyperpolarizing rectangular current pulses while shifting the membrane potential with a DC current source from −70 to −30 mV. FIG. 1A corresponds to data from a control neuron showing the relationships between the input resistance and transmembrane potential which was established by measuring the voltage drop in response to a constant rectangular current pulse injected into the neuron, while shifting the transmembrane voltage to various values by DC current. The value to which the membrane potential was set is indicated on the left-hand side. The relation between Rin and the transmembrane potential in four control neurons is shown in FIG. 1B . Rin was calculated from the voltage drop generated by a 2 sec long, 0.3 nA hyperpolarizing square pulls current injection. These experiments revealed that the Rin of cultured LUQ neurons is nonlinearly related to the membrane potential, reaching a maximum at about −50 mV. Depolarizing the membrane potential to approximately −30 mV lead to increased membrane conductance and often generated an action potential ( FIG. 1A ). With this background information at hand, and in order to evaluate directly the effects of wtSP1 on the transmembrane potential and Rin, wtSP1 (2 μM) was applied to the bathing solution while the membrane potential and input resistance were measured (arrow, FIG. 1C ). Bath application of wtSP1 induced membrane depolarization associated with changes in Rin ( FIGS. 1C and 1D ). FIG. 1D shows the variability in the rate of SP1-induced membrane depolarization (n=5). Within variable time of 3-25 min. of wtSP1 application, the membrane potential (which was set initially to −60 mV by DC current injection) depolarized, reaching a value of −20±3.8 mV (n=5), within approximately 20 min ( FIG. 1C ). The averaged depolarization rate was 5.03±1.03 mV/min (n=5). In parallel to the depolarization, the input resistance initially increased and then rapidly decreased ( FIG. 1C , low panel). Note that approximately 10 min. after SP1 application the membrane depolarized and the input resistance was transiently elevated. Insert in FIG. 1C —representative traces of the recorded voltage drop in response to a constant rectangular current injection pulse before and 15 minutes after wtSP1 application. The initial increase in Rin reflects depolarization-induced inactivation of ion channels, as revealed in the control experiments ( FIGS. 1A and 1B ). Yet, in contrast to the control experiments, after the initial increase in Rin the input resistance of the neurons sharply dropped to values lower than the control that is prior to application of wtSP. In 4 out of 5 experiments the initial increase in Rin was followed by the decrease of Rin to 28±11% of the value prior to wtSP1 application (from 16.6±3.2 MΩ to 4.51±1.91 MΩ, respectively). The documented reduction in Rin represents the partitioning of wtSP1 to the plasma membrane and suggests that the ring-like protein serves as an open nanochannel when in contact with the plasma membrane. wtSP1 can be removed from the plasma membrane by washing with ASW ( FIG. 1E ). In four out of the six experiments, the washout of wtSP1 was associated with recovery of the membrane potential and Rin within 3-12 minutes ( FIG. 1E ). In two out of the 6 experiments, removing wtSP1 did not lead to recovery of the membrane potential and Rin. These neurons eventually degenerated. This variability most likely reflect differences in the level of wtSP1-induced increase in the free intracellular calcium concentration ([Ca 2+ ] i ). Imaging of the [Ca 2+ ] i by fluo-4 revealed that wtSP1 application leads to gradual elevation of the [Ca 2+ ] i (data not shown). Without wishing to be bound by theory, membrane depolarization and decreased Rin by wtSP1 could be generated by two mechanisms: (a) the wtSP1 allows ion flow through its 3 nm inner pore or alternatively (b) the incorporation of wtSP1 into the membrane distorts the organization of the bi-lipid membrane leading to ion leakage. Both mechanisms could lead to membrane depolarization and increased conductance. EXAMPLE 2 Partition of 6His-SP1 into Plasma Membrane The purpose of this experiment was to evaluate whether the wtSP1-induced reduction in Rin was mediated by ion flow through the inner nanopore or in a different way. Therefore, the response of the neurons to the application of a modified derivative of wtSP1, the 6His-SP1 [11] was tested. Results Initially, the effects of 6His-SP1 application on the resting potential and input resistance were evaluated using the approach described above. FIG. 2A shows that application of 2 μM 6His-SP1 resulted in membrane depolarization initially associated with a transient increase in the input resistance followed by a drop of the input resistance to below the control level. Similarly to wtSP1, 2 μM 6His-Sp1 induced membrane depolarization to a mean value of −19.4±5.7 mV within ˜30 min. following application (n=5, FIG. 2A ). This was associated with a decreased Rin to an average value of 21±12% of the value before application (from a mean of 27.34±5.12 MΩ to 6.3±2.51 MΩ, n=6, FIG. 2A low panel, representative alteration). The onset and rate of 6His-SP1-induced membrane depolarization was somewhat slower than that of the wtSP1 (onset time of 11.78±2.63 min. and 7.34±1.73 min. respectively and depolarization rate of 2.15±0.15 mV/min and 5.03±1.03 mV/min respectively, n=5). It was thus concluded that 6His-SP1 partition into the plasma membrane was as for wtSP1. FIG. 2B shows that the dynamics of 6His-SP1-induced membrane depolarization was similar to that of wtSP1. When the inner pore of the 6His-SP1 was blocked by GNPs prior to its bath application, the membrane potential and Rin were not altered. FIG. 2C shows measurements of the membrane potential and input resistance of a single neuron before and after the application of 2 μM 6His-SP1-GNP complex. FIG. 2D shows that the resting potential (3 cells) was not altered by the application of 2 μM 6His-SP1-GNP complex. Bath application of 6His-SP1, to which a GNP (6His-SP1-GNP) were attached prior to its application, did not affect the transmembrane potential or the Rin ( FIGS. 2C and D, n=3). Without wishing to be bound by theory, this result suggests that the inner pore of the SP1 complex underlies the increased membrane conductance. Hypothetically, it is conceivable that binding of GNP to 6His-SP1 prior to its bath application would interfere with the partitioning of the 6His-SP1-GNP into the membrane, thus, preventing its effect on the conductance of the membrane. To differentiate between these possibilities 2 μM 6His-SP1 was applied, and shortly after the onset of membrane depolarization, 4 μM GNPs was applied to the bathing solution ( FIGS. 2E and 2F , n=6). Application of GNPs (4 μM) to the bathing solution after the onset of 6His-SP1-induced depolarization, resulting in partial recovery of the input resistance and the transmembrane voltage, FIGS. 2E and 2F . In all experiments it was found that the addition of GNPs reversed the initial effects of 6His-SP1 on the membrane potential and Rin. The effectiveness of GNPs application revealed large variability ranging from mild improvement to complete recovery. On average, following the application of the GNPs the membrane potential was hyperpolarized by 17.33±3.19 mV (n=6) within 10 minutes of GNPs application, whereas Rin recovered by GNP application to 91±14% of the initial value. These results are consistent with the hypothesis that the GNP binds to 6His-SP1 that was incorporated into the plasma membrane and reduces the 6His-SP1 pore conductance. To address potential nonspecific effects of the GNPs on the membrane ion conductance, GNPs were applied to neurons pre-incubated with wtSP1 ( FIGS. 2G and H). The effects of GNPs on the resting potential and input resistances are expressed only when 6His-SP1 is incorporated into the plasma membrane. Thus, when wtSP1 is applied to the bathing solution and exerts its effects, application of 4 μM GNPs is ineffective in terms of reversing the effects of SP1 on membrane potential and the input resistance ( FIGS. 2H and 2G ). Under these conditions, GNPs application led to 4±1.08 mV membrane hyperpolaryzation (n=4), a significantly smaller hyperpolaryzation than that produced by application of GNPs to 6His-SP1 treated neurons (p<0.05, independent samples t-test). Rin did not recover following GNPs application to a wtSP1 treated neuron (remained at 33±10% relative to the initial values, n=4). Without wishing to be bound by theory, these results indicate that the recovery of the membrane potential and Rin by the GNPs following 6His-SP1 application is the outcome of specific clogging of the 6His-SP1 inner pore by the applied GNPs ( FIG. 3 ).
Provided is a biological membrane including at least one ring-like polypeptide, where the at least one of the ring-like polypeptide is not a membrane protein, a surface being associated with at least one ring-like polypeptide capable of integration into a cell membrane, an electrode including said surface and electronically and biomedical devices including the electrodes for recording and stimulating cell activity.
Identify the most important claim in the given context and summarize it
[ "The Sequence Listing submitted in text format (.", "txt) filed on Nov. 26, 2013, named “SequenceListing.txt”, created on Nov. 25, 2013, 11.1 KB), is incorporated herein by reference.", "TECHNOLOGICAL FIELD This invention generally relates to biomolecular electronics, to an electronic device for communication with living cells and methods of use.", "BACKGROUND One of the major challenges in the use of multi-microelectrode arrays (MEA) in recording (in vitro and in vivo) neuronal network activities is the very low signal to noise ratio.", "This limits the monitoring to field potentials (˜100 μV) generated by action potentials and precludes the detection of sub-threshold synaptic potentials.", "Consequently, large efforts are devoted to the development of nanotechnologies to better couple excitable cells to electronic devices.", "Currently, extracellular MEA is the only available technique for high temporal resolution for multi unit electrical recordings and stimulation.", "However, although this technique reflects synchronized sub threshold activity generated by ensembles of nearby neurons, it does not provide direct information on synaptic potential.", "On the other hand, sharp intracellular microelectrodes and patch-electrodes enable to resolve sub-threshold events with an excellent signal to noise ratio.", "However, the use of such electrodes is limited to a relatively small number of neurons.", "In addition, the duration of recordings and stimulation is limited.", "International application nos.", "WO2004/109282 [1] and WO2008/111047 [2] show that, in cultured non-vertebrate organism, Aplysia , by using an array of chemically functionalized electrodes, it is possible to obtain intracellular recordings of neuronal action potential and sub-threshold synaptic potentials.", "The biological processes enabling these recordings are in line with the observations that the electrodes were engulfed by the Aplysia's neurons and a high seal resistance was generated between the neuron and the electrode and finally that unexpected junctions were formed in the neuron-electrode interface supporting a bidirectional electrical coupling.", "Thus, an increased conductance of the membrane was observed.", "REFERENCES [1] WO2004/109282 [2] WO2008/111047 [3] WO2002/070647 [4] WO2004/022697 [5] WO2007007325 [6] WO2011/027342 [7] Spira, M. E. et al.", ", Use of Aplysia neurons for the study of cellular alterations and the resealing of transected axons in vitro.", "J. Neurosci Methods 69, 91-102 (1996).", "[8] Ziv, N. E. et al.", ", Induction of growth cone formation by transient and localized increases of intracellular proteolytic activity.", "J. Cell Biol.", "140, 223-32 (1998).", "[9] Wang, W. et al.", ", Crystallization and preliminary X-ray crystallographic analysis of SP1, a novel chaperone-like protein.", "Acta Crystallogr D Biol Crystallogr 59, 512-4 (2003).", "[10] Wang, W. X. et al.", ", Aspen SP1, an exceptional thermal, protease and detergent-resistant self-assembled nano-particle.", "Biotechnol.", "Bioeng.", "95, 161-8 (2006).", "[11] Medalsy, I. et al.", ", SP1 protein-based nanostructures and arrays.", "Nano Lett.", "8, 473-7 (2008).", "[12] Malkinson, G. et al.", ", Calcium concentration threshold and translocation kinetics of EGFP-DOC2B expressed in cultured Aplysia neurons.", "Cell Calcium 39, 85-93 (2006).", "[13] Khoutorsky, A. et al.", ", Calpain inhibitors alter the excitable membrane properties of cultured Aplysia neurons.", "J. Neurophysiol 100, 2784-93 (2008).", "GENERAL DESCRIPTION The present invention is based on findings by the inventors that ring-like non-membrane polypeptides spontaneously partition (integrate, intercalate, embed) into cell membranes.", "These ring-like polypeptides orient in the membrane such that they form nanopores within the membrane and subsequently modulate the membrane's properties.", "The degree of partitioning and generation of the nanopores may be controlled by predefining the number of ring-like non-membrane polypeptides to be integrated in the membrane.", "The nanopores may be made partially or fully closed, for example, by placing in the nanopores “plugs”", "in the form of nanoparticles, such as gold nanoparticles.", "Interestingly, formation of nanopores in the membrane of an electrically active cell or a cell having physiological response to electric stimulation may provide neuroelectronic interface that may assist in intracellular recordings and stimulation of many such individual cells.", "Thus, the invention disclosed herein has the advantage of permitting to control and fine-tune the recording and/or stimulation of a desired cell by controlling the extent of nanopore formation.", "Specially, the inventors have found that ring-like polypeptides, such as SP1 and derivatives thereof, which are absent from natural animal cell membranes, form nanopores in membranes of living animals cells and increase the membrane conductance.", "The integration of such a ring-like polypeptide may be substantially irreversible.", "However, as demonstrated herein, it is possible to reverse the effect induced by such ring-like polypeptides, as SP1 polypeptide, or a derivative thereof such as 6His-SP1, on the membrane conductance, by addition of, e.g., gold nanoparticles (GNP), as explained hereinabove, either prior to or after the partition of the polypeptides into the membrane.", "Therefore, in accordance with a first aspect, the present invention provides a biological membrane comprising at least one ring-like polypeptide, wherein the at least one ring-like polypeptide is not a membrane protein (or is not a membrane protein naturally associated with said biological membrane).", "The “ring-like polypeptide”", "is an oligomeric polypeptide (protein) arranged in a circular ring shape (ring-like), namely having a central cavity (as inner pore or inner hole) and having an outer radius defining the outer rim of the ring-like structure and an inner radius defining the radius of the cavity.", "The polypeptide may comprise several monomeric subunits, being either identical (homo) or different (hetero) from each other, together having a ring-like structure, e.g., complex polypeptides.", "The polypeptide may be a native homo-oligomer or hetero-oligomer comprising monomeric subunits arranged, for example, in a concentric arrangement.", "As disclosed herein, the ring-like polypeptide partitioned (integrated, intercalated) in the cell membrane, in accordance with the invention, is a “non-membrane polypeptide”", "naturally not found in animal cell membranes, e.g., in human cell membranes, under physiological conditions (extracellular or intracellular conditions that may occur in nature for that organism or cell system, in contrast to artificial conditions possibly in a laboratory).", "In other words, the ring-like polypeptide is not naturally located in the plasma membrane or any membrane of a living animal cell.", "In some embodiments, the ring-like polypeptide used in accordance with the invention is a heat shock protein (HSP), a functionally related protein involved in the folding and unfolding of other proteins.", "The expression of HSP is increased when cells are exposed to elevated temperatures and other stress.", "According to some embodiments, the ring-like polypeptide is HSP 60, HSP 70, HSP90.", "According to some embodiments, the ring-like polypeptide is thermolysin.", "In other embodiments, the ring-like polypeptide is a boiling stable polypeptide, having a structural oligomeric stability following treatment at about 95° C., in an aqueous solution, for at least 10 minutes, as determined by a size fractionation assay.", "In further embodiments, the ring-like polypeptide is a denaturant-stable polypeptide, having a structural oligomeric stability of an oligomeric protein following treatment in aqueous solution containing 1:2,000 molar ratio (monomer:SDS), as determined by a size fractionation assay.", "Still according to some embodiments, the ring-like polypeptide is a stable protein variant.", "In some embodiments, the ring-like polypeptide is stable protein 1 (SP1) polypeptide [3-5].", "The preparation, structural modification (mutations) and characteristics of SP1 are disclosed in international patent application nos.", "WO2002/070647 [3], WO2004/022697 [4], WO2007/007325 [5] and WO2011/027342 [6], and corresponding US patent applications, each being incorporated herein by reference.", "SP1 is a homo-dodecamer oligomeric protein, with an outer diameter of 11 nm and an inner diameter of 3 nm.", "SP1 is naturally localized in the cytoplasm of plant cells and is not found in animal, e.g., mammalian (human or non-human) cells.", "In some embodiments, the SP1 polypeptide is the wild type polypeptide (disclosed, for example, in [6] as SEQ ID NO: 4) or any derivatives thereof (disclosed, for example, in any of references [3-6], each being incorporated herein by reference).", "The term “derivatives thereof”", "is used herein to denote any genetically modified variant of wild type SP1 including fragments thereof, homologous thereof or mutations thereof.", "Modifications of the SP1 polypeptide may enhance the protein functionality, for example, in interaction with a surface, as disclosed hereinbelow.", "As appreciated by those versed in the art, genetic modification of a polypeptide is of common practice and includes mutations in the polynucleotide encoding the respective polypeptide, such that a selective mutation in the nucleotide sequence would result in a desired amino acid mutation.", "Any mutation of the SP1 polypeptide referred to herein is a mutation based on the wild-type polypeptide.", "Mutations in the polypeptide may include substitutions (mutations) of at least one amino acid, deletion of at least one amino acid or addition of at least one amino acid.", "Thus, the polypeptide used in accordance with the present invention may be selected from the wild-type SP1 polypeptide, cysteine mutated/substituted/added SP1 polypeptide, and histidine mutated/substituted/added SP1 polypeptide.", "In some embodiments, the SP1 polypeptide is wild-type SP1 polypeptide (SEQ ID NO:1).", "In some embodiments, the SP1 polypeptide is a polypeptide encoded by the polynucleotide deposited in NCBI under GenBank: AJ276517.1 (SEQ ID NO:8).", "In other embodiments, the SP1 polypeptide comprises additional histidine residues (SEQ ID NO:2) and encoded by the polynucleotide having the sequence SEQ ID NO:9.", "The 6His-SP1 derivative describes herein corresponds to SEQ ID NO:2.", "In further embodiments, the SP1 polypeptide is a homologous variant to wild type SP1.", "The homologous variant may comprise for example deletion of amino acids in the N-terminal region of the wild type SP1.", "In some embodiments, the SP1 polypeptide is a variant polypeptide with a deletion of amino acids in the N-terminal region.", "This variant SP1 polypeptide having SEQ ID NO:3, being encoded by the polynucleotide having the sequence SEQ ID NO:10.", "In some embodiments, the SP1 polypeptide comprises mutations of amino acids to cysteine.", "Non-limiting examples for such a cysteine-mutated SP1 polypeptides include SEQ ID NO:4 (encoded by the polynucleotide having the sequence SEQ ID NO:11);", "SEQ ID NO:5 (encoded by the polynucleotide having the sequence SEQ ID NO:12);", "SEQ ID NO:6 (encoded by the polynucleotide having the sequence SEQ ID NO:13);", "and SEQ ID NO:7 (encoded by the polynucleotide having the sequence SEQ ID NO:14).", "As described throughout, the non-membrane polypeptides spontaneously partition in the plasma membrane of living animal cells and modulate their properties;", "the biological membrane thus being regarded as a modified membrane.", "The “biological membrane”", "in which the polypeptide, e.g., SP1, is integrated, may be any membrane having at least a bilayer of lipid molecules.", "The biological membrane is, in some embodiments, a natural membrane, such as a cell membrane (plasma membrane) which includes proteins embedded within the lipid bilayer and which separates the interior of cells from the outside environment.", "In some embodiments, the cell of which membrane is modified, in accordance with the invention, is an animal cell.", "In some embodiments, the cell is from a vertebrate or non-vertebrate organism.", "In some embodiments, the cell is a mammalian cell.", "In some embodiments, the cell is a human cell or non human cell.", "In some embodiments, the cell is selected from a neuron, a muscle cell, a cell of a secreting gland and others.", "In some embodiments, the cell is a human cell selected from a neuron, a muscle cell, a cell of a secreting gland and others.", "In some embodiments, the biological membrane is not one which does not comprise any characteristics of a plasma membrane (for example lipids and proteins).", "In some embodiments, the biological membrane may be an artificial biological membrane model, such as liposomal membrane, composed of a lipid bilayer.", "It should be appreciated that upon integration of the polypeptide, e.g., SP1 into the cell membrane, the polypeptide adopts a spatial orientation with respect to the lipid bilayer.", "Without wishing to be bound by theory, it is believed that the polypeptide is oriented in the membrane such that transfer of materials through the polypeptide inner pore is enabled, thus constituting after intercalation, the nanopores in the cell membrane.", "The terms “nanopore”", "and “nanochannel”", "denote the pores (holes) in the membrane.", "In some embodiments, each of the nanopores has, on average, a diameter of up to about 10 nm;", "in other embodiments, up to about 3 nm;", "and in further embodiments, up to 2.5 nm.", "In some embodiments, the polypeptide nanopore is associated with a metal nanoparticle, said nanoparticle, when present in the nanopore, acting as a plug which closes the nanopore from material transfer therethrough.", "The “nanoparticle”", "may be of any metal or an alloy of metals.", "Non-limiting examples of such metals are gold, platinum, silver, iron, copper, nickel, palladium, iridium, and titanium.", "In some embodiments, the size of the nanoparticle is from about 1 nm to about 10 nm;", "in other embodiments, from about 1 nm to about 5 nm;", "and in further embodiments, from about 1 nm to about 3 nm.", "In some embodiments, the nanoparticle is a gold nanoparticle.", "In further embodiments, the polypeptide is SP1 [SEQ ID NO:1], SP1 variant [SEQ ID NO:3] or 6His-SP1 [SEQ ID NO:2].", "Thus, the invention provides a biological membrane (modified membrane) comprising SP1 [SEQ ID NO:1] or 6His-SP1 polypeptide [SEQ ID NO: 2], wherein the inner pore of said polypeptide being occupied a gold nanoparticle.", "In some embodiments, the modified membrane in which the polypeptide, e.g., SP1 or 6His-SP1 is integrated (whether or not the polypeptide is associated with a metal nanoparticle) may be associated with a surface.", "The surface may have any predefined geometry that may be a stand-alone construct being used to minimize any possible movement of the membrane and may be composed of a metallic material or coated with such a material.", "The metal may be any metallic element, compound or alloy that is electrically conductive.", "In some embodiments, the surface is a metallic surface or coated with a metallic layer rendering it conductive.", "In some embodiments, the surface is of a material selected from gold, platinum, silver, nickel, palladium and silicon.", "The association with the surface may be through one or more linking groups, which act to link the surface with the polypeptide moiety integrated in said membrane and/or with a region of the cell membrane which is not a region defined by the integrated polypeptide.", "The association of the surface with the polypeptide residue, or with other regions of the membrane may be via a pendent (native or modified) bifunctional moiety capable of association with the surface (via one functional group of the bifunctional moiety) and with the polypeptide/membrane (via the same or different group of the bifunctional moiety).", "The surface binding moiety may be selected from a thiol, a carboxylic acid (or a carboxylate), an amine, an amide, an alcohol (or an alkoxy), a siloxy, and others.", "The polypeptide/membrane binding moiety may be selected from a thiol, a carboxylic acid (or a carboxylate), an amine, an amide, an alcohol (or an alkoxy), and others.", "In some embodiments, the bifunctional moiety is selected from homo-bifunctional linkers and hetero-bifunctional linkers.", "In some embodiments, the homo-bifunctional linker, having the same type of group at either end, may be selected from, for example, glutaraldehyde, bis(imidoesters) and bis(succinimidylesters) (also known as NHS esters).", "In some embodiments, the hetero-bifunctional linkers, having different type of binding groups, may be selected from, for example, [succinimidyl 3-(2-pyridyldithio)propionate] (SPDP), [succinimidyl trans-4-(maleimidylmethyl)cyclohexane-1-carboxylate] (SMCC) and Succinimidyl-4-(p-maleimidophenyl)butyrate (SMPB).", "In some embodiments, the surface and polypeptide/membrane binding moieties are bonded to each other through a linking moiety which may be a straight chain or branched chain organic group, such as a C1-C20 alkylene group.", "In some embodiments, the linking moiety is a C1-C4 alkylene group.", "In some embodiments, the association of the surface with the polypeptide/membrane is via one or more (plurality) amino acid groups, non-limitedly selected from glycine, alanine, histidine, cysteine and methionine residues.", "As indicated herein, the amino acid may be a pendant group on the polypeptide/membrane structure or a moiety (amino acid) of the polypeptide sequence.", "In some embodiments, said amino acid is cysteine.", "In some embodiments, the association is via a polymer, a peptide, a carbohydrate, a lipid, or a nucleic acid.", "The association with the surface may be by a variety of chemical and/or physical interactions, such as covalent bonding, hydrogen bonding, electrostatic interaction, complexation, van der Walls interaction and ionic interaction.", "In some embodiments, the interaction is covalent bonding.", "The surface, with which the modified membrane of the invention is associated, may be a surface region of at least one element of a device, e.g., an electronic or optical device, e.g., for recording or stimulating a tissue.", "In some embodiment, the device is an electronic device.", "In other embodiments, the surface region is an electrode surface region.", "In further embodiments, the surface is a surface region of a cell-communicating component of an electrode;", "the component being adapted for sensing and/or stimulating a cell activity.", "In some embodiments, the surface may be at least a surface region of an electrode.", "Thus, the invention provides an electrode being associated on at least a region of its surface with a biological membrane comprising at least one ring-like polypeptide.", "In some embodiments, the at least one ring-like polypeptide is not a membrane protein.", "In other embodiments, the polypeptide is SP1 [SEQ ID NO: 1], a variant of SP1 [SEQ ID NO:3] or cysteine-mutated variants of SP1 having for example [SEQ ID NO:4], [SEQ ID NO:5], [SEQ ID NO:6] or [SEQ ID NO:7].", "In further embodiments, the biological membrane is a membrane of a living animal cell.", "As used herein, the electrode of the invention is associated with a current source and configured to apply current to a tissue, ex vivo or in vivo.", "The electrode may be any one of a gold electrode, a platinum electrode, a carbon electrode, a silver electrode, a nickel electrode, or a palladium electrode.", "The electrode may be a regular electrode or a gate electrode.", "In some embodiments, the gate electrode may be an ion sensitive gate.", "The ion-sensitive material may be Aluminum Oxide (Al 2 O 3 ), Silicon Nitride (Si 3 N 4 ), Indium Tin Oxide (In 2 O 3 —Sn 2 O 3 ), Silicon Oxide (SiO 2 ) or Tantalum Oxide (Ta 2 O 5 ).", "In some embodiments, the electrode is an electrode intended to communicate with cells having electric properties, or having physiological responses to electrical stimulation, such as neurons, muscle cells, and cells of secreting glands.", "The electrode may be part of an electrode assembly.", "In some embodiments, said electrode assembly comprises a pair of source-drain electrodes.", "In other embodiments, said assembly comprises at least a pair of source-drain electrodes and at least one gate electrode.", "As appreciated, the invention permits utilization of ring-like polypeptides, such as SP1 or its various derivatives, to electrically and chemically couple sensing pads of electronic devices (transistors gates or passive electrodes) and living cells.", "This clearly facilitates assembly of neuroelectronic hybrid systems or generate chemical and electrical coupling in vitro or in vivo.", "Electrical communication between an electrode according to the present invention and a cell may achieve one or more of: 1.", "Detection and recording of the presence of current in cells by the electrode or detection of a current change;", "Detection and recording of changes in potential on plasma membrane of cells or changes in said potential;", "Providing current to cells;", "and 4.", "Applying an electric field to cells.", "The cell which membrane is modified by a polypeptide in accordance with the invention may be a cell ex vivo or in vivo.", "For some applications, particularly such which require stimulation or recording of cells in vivo, the construction of a modified cell membrane onto, e.g., an electrode surface may be achieved by first associating the polypeptide to said surface and subsequently permitting integration of the polypeptide into a cell membrane in vivo.", "Thus, according to another aspect, the present invention provides a surface, e.g., an electrode surface, for adherence of cells thereto, at least a region of the surface being in association with at least one (plurality of) ring-like polypeptide capable of (adapted for, for use in, for permitting) integration into a cell membrane (upon contact therewith and under physiological conditions), said ring like polypeptide not being a membrane protein.", "Association between the surface region and the polypeptide is as disclosed hereinabove.", "As defined above, the surface may have a predefined geometry, optionally comprising at least one curved structure.", "The curved structure may be an elliptical structure or generally a micronail structure having a micrometer or nanometer scale contact region with the membrane surface.", "The “micronail”, in the context of the present invention, is a micrometer or nanometer scale protrusion from the surface.", "The surface may comprise one or more such micronail structures, which may be identical to each other in their chemical properties, shape and size or which differ from each other in at least one of chemical properties, shape and size.", "Each of the micronails acting as individual spaced apart electrodes, distributed to optimize engulfment/wrapping/internalization by a cell membrane.", "The interaction between the surface and the cells membrane, i.e., engulfment/wrapping/internalization, may comprise wrapping (engulfment) of the cells membranes around the surface without disturbing the integrity of the membrane.", "The surface is defined as having cellular-engulfing promoting properties, resulting from the morphology and dimensions of the surface, and/or from the inherent physical and chemical properties of the surface material from which it is formed (such as metal selected from gold, copper, aluminum, platinum, silver, alloys of these metals or combinations thereof) or which is coated with.", "The surface may be coated by molecules that recognize plasma membrane components, such molecules may be selected from a protein, a lipid, a polysaccharide, a glycoprotein, and others.", "Examples of such molecules are ligand of plasma membrane receptors (or receptor binding parts of said ligand), receptors that recognize plasma membrane components;", "lectins that bind to plasma membrane glycoproteins;", "antibodies that recognize plasma membrane components (either proteins or non-proteins) or binding fragments of said antibodies;", "integrins that recognize short linear amino acids present in extracellular proteins, or a combination of two or more of these proteins.", "The structure, dimensions and density of the surface can be optimized to maximize the electrical and chemical coupling between the hybrid components, namely the transistor and the living cell.", "In accordance with this aspect of the invention, at least a region of the surface, e.g., electrode surface, is wrapped by the cell (via a mechanism know as phagocytosis/pinocytosis or endocytosis) and in view of the integration of the polypeptide into the cells'", "membrane, the existing membrane nanopores allow part of the surface to pass through the plasma membrane into (or become in contact, or interact with) the cytoplasm and allow the membrane to close around the surface, forming a giga-seal between the plasma membrane and the surface.", "The passing of the surface inside the cells'", "cytoplasm allows sensing and recording at least one of electrical and chemical events inside the cells, as well as electrical stimulation from inside the cells.", "According to some embodiments, the present invention provides a metallic surface, e.g., an electrode, wherein at least a region of the surface is associated with a membrane integrated with at least one SP1 polypeptide or any derivative thereof.", "In accordance with yet another aspect, the present invention provides a device comprising an electrode arrangement having at least one electrode, wherein at least a region of a surface of the electrode being associated with a modified membrane, as described herein.", "In accordance with yet a further aspect, there is provided a device for interaction with a cell, the device comprising an electrode which at least a region of its surface being associated with a modified membrane according to the invention, the interaction being via non-membrane ring-like polypeptides present on the cell membrane, said interaction permitting at least one of a chemical and electrical interaction between the electrode surface and the cell cytoplasm.", "In accordance with yet a further aspect, there is provided a device for interaction with a cell, the device comprising an electrode which surface being capable of association with a cell cytoplasm, wherein said surface being associated with at least one non-membrane ring-like polypeptide, said polypeptide being capable of undergoing intercalation into a cell membrane for permitting at least one of a chemical and electrical interaction between the electrode surface and the cell cytoplasm.", "Electrical communication using such an electrode or an electric device may be carried out for a variety of purposes ranging from basic research to diagnostic means and biomedical devices being used in numerous cells and tissues.", "The tissue cells may be any type of cell of interest, especially for electrical recording/stimulating purposes, the cells are typically (but not exclusively) excitable cells such as neurons, muscles endocrine cells and others (of any species).", "The increased conductance observed in the membranes comprising the at least one ring like polypeptide may be used in a variety of experimental technologies such as recording of low signal to noise ratio neuronal network activity in cells and hence to obtain a better understanding of the neural network.", "Further, the device may be used in multielectrode array (MEA).", "The device described throughout may be used for diagnostic.", "Further, the electronic device according to the present disclosure may be used for the construction of biomedical devices;", "especially those which need a functional link between nerves or muscles to electric components.", "Thus, in accordance with yet another aspect, the present invention provides a biomedical device, said device comprising an electrode which surface being capable of association with a tissue cell cytoplasm, wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into a cell membrane of said tissue, for permitting at least one of a chemical and electrical interaction between the electrode surface and the cell cytoplasm.", "In some embodiments, the biomedical device may be prosthesis (also termed prosthetic), namely an artificial device extension that replaces a missing body part by using mechanical devices with human muscle, skeleton or a system to assist or enhance motor control lost by trauma, disease or defect by functionally linking between the cells and the electronic sensing and recording device as described herein.", "An electrode or the device according to the invention may be used, for example, to electrically record cell, e.g., neuronal activity (neuronal signals) in a tissue, ex vivo or in vivo e.g., the brain.", "This recording may be used to restore mobility or assist in controlling devices.", "Thus, the invention also provides a recording device, said device comprising an electrode which surface being capable of association with neuronal cells, wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into a cell membrane of said neuron, for permitting at least one of a chemical and electrical interaction between the electrode surface and the neuronal cells.", "In some embodiments, the device is used for recording neuronal activity (signal) in vivo, e.g., in the brain to improve, increase or induce mobility or neural stimulation of a body part.", "In some embodiments, the biomedical device is an implant.", "An electrode or the device according to the invention may be used, for example, as a retinal implant (an intraocular prosthetic device), by electrically stimulating retinal cells.", "In addition, it may be used as a cochlear implant that is an implanted surgical device that provides a sense of sound.", "Thus, the invention also provides a retinal implant, said implant comprising a electrode which surface being capable of association with cells of a tissue region of the retina, wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into a cell membrane of said retina, for permitting at least one of a chemical and electrical interaction between the electrode surface and the retina cells.", "In some embodiments, the retinal implant is used for stimulating nerve cells in the retina to induce, improve or increase light sensitivity (and subsequently vision).", "The invention further provides an ear implant (e.g., cochlear implant), said implant comprising a electrode which surface being capable of association with cells of a tissue region of the ear (e.g., the inner ear), wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into a cell membrane of said ear region, for permitting at least one of a chemical and electrical interaction between the electrode surface and the ear tissue cells.", "In some embodiments, the ear implant is used for stimulating nerve cells in the ear tissues to induce, improve or increase sensitivity to sound (and subsequently hearing).", "The invention further provides a method for electrically stimulating cells of a tissue region, said method comprising: positioning adjacently to a tissue region a device comprising an electrode which surface being capable of association with cells of said tissue region, wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into cell membranes of cells present in said tissue region, permitting internalization/engulfing/wrapping of said cell membranes around said electrode surface and intercalation of said at least one non-membrane ring-like polypeptide in said cell membrane;", "and electrically stimulating said cells in said tissue region.", "In some embodiments, the stimulation is in vivo.", "In some embodiments, said tissue to be stimulated in accordance with the method of the invention, is a tissue of the eye or the ear.", "In further embodiments, said cells are selected from a neuron, a muscle cell, a cell of a secreting gland, and others.", "The invention further provides a method for electrically recording cells of a tissue region, said method comprising: positioning adjacently to a tissue region a device comprising an electrode which surface being capable of association with cells of said tissue region, wherein said surface being associated with at least one non-membrane ring-like polypeptide capable of undergoing intercalation into cell membranes of cells present in said tissue region, permitting internalization/engulfing/wrapping of said cell membranes around said electrode surface and intercalation of said at least one non-membrane ring-like polypeptide in said cell membrane;", "and electrically recording activity of said cells in said tissue region.", "In some embodiments, the recording is of a tissue activity in vivo.", "In some embodiments, said tissue to be recorded in accordance with the method of the invention, is a brain tissue.", "In further embodiments, said cells are neuronal cells.", "In accordance with another aspect, the present invention provides a process for the preparation of a modified biological membrane, according to the present invention, the process comprising: proving a biological membrane in a growth medium;", "adding an amount of a ring-like polypeptide to the growth medium, wherein said polypeptide is not a membrane polypeptide;", "and allowing said polypeptide to integrate into said membrane and forming nanopores in said membrane thereby resulting in a modified biological membrane.", "The term “growth medium”", "denotes a liquid or gel designed to support the growth of biological membranes.", "In some embodiments, the biological membrane is a cell membrane and thus the term growth medium denotes a culture medium.", "The growth medium may comprise, for example, source of amino acids, sugars, antibiotics.", "In some embodiments, the biological membrane is an artificial membrane, thus the growth medium is regarded as a medium allowing the stability of the artificial membrane within.", "In accordance with this aspect, the amount of ring like polypeptide to be added to the growth medium may be determined a priory in order to allow the control on the amount of nanopores formed within the membrane.", "BRIEF DESCRIPTION OF THE DRAWINGS In order to understand the disclosure and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: FIGS. 1A-1E are graphs showing that wtSP1 induces membrane depolarization and decreased input resistance.", "FIG. 1A shows voltage drop in response to a constant rectangular current pulse injected into the neuron;", "FIG. 1B is a graph showing the relations between Rin and the transmembrane potential;", "FIG. 1C is a graph showing the effects of wtSP1 on the transmembrane potential and Rin;", "FIG. 1D is a graph showing the rate of SP1-induced membrane depolarization, SP1 application is indicated by an arrow;", "FIG. 1E is a graph showing the effects of wtSP1 washing on membrane potential, the onset of the wash is indicated by the dashed line.", "FIGS. 2A-2H are graphs showing the reversible conductance blockade of the 6HIS-SP1 inner pore by gold nanoparticles.", "FIG. 2A is a graph showing the effect of 6His-SP1 on the transmembrane potential and Rin;", "FIG. 2B is a graph showing the dynamics of 6His-SP1-induced membrane depolarization;", "FIG. 2C is a graph showing the membrane potential and input resistance of a single neuron before and after the application of 2 μM 6His-SP1-GNP complex;", "FIG. 2D is a graph showing the resting potential after the application of 6His-SP1-GNP complex;", "FIGS. 2E and 2F are graphs showing effect of application of GNPs to the bathing solution after the onset of 6His-SP1-induced effects on the transmembrane potential and Rin ( FIG. 2E ) and membrane depolarization ( FIG. 2F );", "FIGS. 2G and 2H are graphs showing the effects of application of GNPs to the bathing solution after the onset of wtSP1-induced effects on the transmembrane potential and Rin ( FIG. 2G ) and membrane depolarization ( FIG. 2H ).", "FIG. 3 is a schematic representation showing the attachment of an SP1 derivative to the plasma membrane and the blocking of the SP1 conducting pore by a nano-gold particle.", "FIG. 4 depicts the SP1 nucleotide sequence (SEQ ID NO:8) and the deduced (encoded) SP1 protein sequence (SEQ ID NO:1).", "FIG. 5 depicts a nucleotide sequence (SEQ ID NO:9) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:2).", "FIG. 6 depicts a nucleotide sequence (SEQ ID NO:10) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:3).", "FIG. 7 depicts a nucleotide sequence (SEQ ID NO:11) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:4).", "FIG. 8 depicts a nucleotide sequence (SEQ ID NO:12) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:5).", "FIG. 9 depicts a nucleotide sequence (SEQ ID NO:13) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:6).", "FIG. 10 depicts a nucleotide sequence (SEQ ID NO:14) and the deduced SP1 variant (mutant) protein sequence (SEQ ID NO:7).", "DETAILED DESCRIPTION OF EMBODIMENTS Materials and Methods Neurons Culture Left upper quadrant neurons (LUQ) from the abdominal ganglion of juvenile Aplysia (2-5 g) were cultured, as previously described [7, 8].", "Briefly, animals were anesthetized by injection of isotonic MgCl 2 solution.", "The ganglia were isolated and incubated for 1.5-3 h in 1% protease (Type IX, Sigma) at 34° C. The ganglia were then de-sheathed, and the cell bodies or their neurons with their long axons were pulled out with sharp micropipets and placed on poly-L-lysine coated (Sigma) glass bottom culture dishes.", "The culture medium consisted of 10% filtered hemolymph from Aplysia faciata collected along the Mediterranean coast, and L-15 (Gibco-BRL) supplemented for marine species.", "Twenty-four hours after plating dishes were transferred to an 18° C. incubator.", "Experiments were preformed 3-5 days after plating.", "Electrophysiology All experiments were performed at room temperature in artificial sea water (ASW) composed of NaCl 460 mM, KCL 10 mM, CaCl 2 10 mM, MgCl 2 55 mM and HEPES [N-(2-hydroxyethyl)-piperazine-N′-2-ethanesulfonic acid, Sigma] 11 mM, adjusted at pH 7.6.", "Recording and stimulation of LUQ neurons were conducted in current-clamp mode using sharp 5-10 MΩ glass microelectrodes filled with 2M KCl.", "The microelectrode served for both current injection and voltage recording (Axoclamp-2A;", "Axon Instruments).", "Signals were digitally recorded by means of a Digidata 1322A interface (Axon Instruments, Union City, Calif.) and analyzed with Clampfit software (Axon Instruments).", "SP1 and 6His-SP1 Expression and purification of all SP1 mutants were performed as described previously, wild-type SP1 (wtSP1) [9, 10] and 6His-SP1 [11].", "SP1 and 6His-SP1 were applied to the bathing solution in ASW to generate a final concentration of 2 μM.", "Ca Imaging Calcium imaging was conducted as previously reported [12].", "Briefly, the system used for confocal calcium imaging consisted of an Olympus microscope IX70 and a Bio-Rad (Hercules, Calif.) Radiance 2000/AGR-3 confocal imaging system.", "The objective used was an Olympus planApo 60×1.4 NA oil objective.", "The images were collected and processed using LaserSharp and LaserPix BioRad software, respectively.", "For the experiments, fluo-4 10 mM (pentapotassium salt, Invitrogen) in 0.5 KCl was pressure microinjected into the neurons.", "Imaging was preformed after the dye has equilibrated throughout the main axon and the small neuritis (approximately 30 minutes after the injection).", "Fluo-4 was excited with 488 nm (Argon laser), and the emission was collected at 500-560 nm.", "EXAMPLE 1 Partition of wtSP1 into Plasma Membrane The purpose of this experiment was to examine if wtSP1, dispersed in a physiological solution, spontaneously partition into the bi-lipid membrane of living neurons and form nanopores.", "Methods The culture medium, which contains Aplysia hemolymph, was replaced by artificial sea water (ASW), an ionic solution.", "A cultured neuron was then impaled by a sharp glass microelectrode that served for both current injections and voltage recordings [13].", "Results The input resistance (Rin) of the neuron was calculated from the transmembrane voltage drop generated by small intracellular hyperpolarizing rectangular 0.3 nA current pulses lasting 2 s ( FIG. 1 ).", "The relations between the transmembrane potential and the neuron's input resistance were determined in control experiments by intracellular injection of the hyperpolarizing rectangular current pulses while shifting the membrane potential with a DC current source from −70 to −30 mV.", "FIG. 1A corresponds to data from a control neuron showing the relationships between the input resistance and transmembrane potential which was established by measuring the voltage drop in response to a constant rectangular current pulse injected into the neuron, while shifting the transmembrane voltage to various values by DC current.", "The value to which the membrane potential was set is indicated on the left-hand side.", "The relation between Rin and the transmembrane potential in four control neurons is shown in FIG. 1B .", "Rin was calculated from the voltage drop generated by a 2 sec long, 0.3 nA hyperpolarizing square pulls current injection.", "These experiments revealed that the Rin of cultured LUQ neurons is nonlinearly related to the membrane potential, reaching a maximum at about −50 mV.", "Depolarizing the membrane potential to approximately −30 mV lead to increased membrane conductance and often generated an action potential ( FIG. 1A ).", "With this background information at hand, and in order to evaluate directly the effects of wtSP1 on the transmembrane potential and Rin, wtSP1 (2 μM) was applied to the bathing solution while the membrane potential and input resistance were measured (arrow, FIG. 1C ).", "Bath application of wtSP1 induced membrane depolarization associated with changes in Rin ( FIGS. 1C and 1D ).", "FIG. 1D shows the variability in the rate of SP1-induced membrane depolarization (n=5).", "Within variable time of 3-25 min.", "of wtSP1 application, the membrane potential (which was set initially to −60 mV by DC current injection) depolarized, reaching a value of −20±3.8 mV (n=5), within approximately 20 min ( FIG. 1C ).", "The averaged depolarization rate was 5.03±1.03 mV/min (n=5).", "In parallel to the depolarization, the input resistance initially increased and then rapidly decreased ( FIG. 1C , low panel).", "Note that approximately 10 min.", "after SP1 application the membrane depolarized and the input resistance was transiently elevated.", "Insert in FIG. 1C —representative traces of the recorded voltage drop in response to a constant rectangular current injection pulse before and 15 minutes after wtSP1 application.", "The initial increase in Rin reflects depolarization-induced inactivation of ion channels, as revealed in the control experiments ( FIGS. 1A and 1B ).", "Yet, in contrast to the control experiments, after the initial increase in Rin the input resistance of the neurons sharply dropped to values lower than the control that is prior to application of wtSP.", "In 4 out of 5 experiments the initial increase in Rin was followed by the decrease of Rin to 28±11% of the value prior to wtSP1 application (from 16.6±3.2 MΩ to 4.51±1.91 MΩ, respectively).", "The documented reduction in Rin represents the partitioning of wtSP1 to the plasma membrane and suggests that the ring-like protein serves as an open nanochannel when in contact with the plasma membrane.", "wtSP1 can be removed from the plasma membrane by washing with ASW ( FIG. 1E ).", "In four out of the six experiments, the washout of wtSP1 was associated with recovery of the membrane potential and Rin within 3-12 minutes ( FIG. 1E ).", "In two out of the 6 experiments, removing wtSP1 did not lead to recovery of the membrane potential and Rin.", "These neurons eventually degenerated.", "This variability most likely reflect differences in the level of wtSP1-induced increase in the free intracellular calcium concentration ([Ca 2+ ] i ).", "Imaging of the [Ca 2+ ] i by fluo-4 revealed that wtSP1 application leads to gradual elevation of the [Ca 2+ ] i (data not shown).", "Without wishing to be bound by theory, membrane depolarization and decreased Rin by wtSP1 could be generated by two mechanisms: (a) the wtSP1 allows ion flow through its 3 nm inner pore or alternatively (b) the incorporation of wtSP1 into the membrane distorts the organization of the bi-lipid membrane leading to ion leakage.", "Both mechanisms could lead to membrane depolarization and increased conductance.", "EXAMPLE 2 Partition of 6His-SP1 into Plasma Membrane The purpose of this experiment was to evaluate whether the wtSP1-induced reduction in Rin was mediated by ion flow through the inner nanopore or in a different way.", "Therefore, the response of the neurons to the application of a modified derivative of wtSP1, the 6His-SP1 [11] was tested.", "Results Initially, the effects of 6His-SP1 application on the resting potential and input resistance were evaluated using the approach described above.", "FIG. 2A shows that application of 2 μM 6His-SP1 resulted in membrane depolarization initially associated with a transient increase in the input resistance followed by a drop of the input resistance to below the control level.", "Similarly to wtSP1, 2 μM 6His-Sp1 induced membrane depolarization to a mean value of −19.4±5.7 mV within ˜30 min.", "following application (n=5, FIG. 2A ).", "This was associated with a decreased Rin to an average value of 21±12% of the value before application (from a mean of 27.34±5.12 MΩ to 6.3±2.51 MΩ, n=6, FIG. 2A low panel, representative alteration).", "The onset and rate of 6His-SP1-induced membrane depolarization was somewhat slower than that of the wtSP1 (onset time of 11.78±2.63 min.", "and 7.34±1.73 min.", "respectively and depolarization rate of 2.15±0.15 mV/min and 5.03±1.03 mV/min respectively, n=5).", "It was thus concluded that 6His-SP1 partition into the plasma membrane was as for wtSP1.", "FIG. 2B shows that the dynamics of 6His-SP1-induced membrane depolarization was similar to that of wtSP1.", "When the inner pore of the 6His-SP1 was blocked by GNPs prior to its bath application, the membrane potential and Rin were not altered.", "FIG. 2C shows measurements of the membrane potential and input resistance of a single neuron before and after the application of 2 μM 6His-SP1-GNP complex.", "FIG. 2D shows that the resting potential (3 cells) was not altered by the application of 2 μM 6His-SP1-GNP complex.", "Bath application of 6His-SP1, to which a GNP (6His-SP1-GNP) were attached prior to its application, did not affect the transmembrane potential or the Rin ( FIGS. 2C and D, n=3).", "Without wishing to be bound by theory, this result suggests that the inner pore of the SP1 complex underlies the increased membrane conductance.", "Hypothetically, it is conceivable that binding of GNP to 6His-SP1 prior to its bath application would interfere with the partitioning of the 6His-SP1-GNP into the membrane, thus, preventing its effect on the conductance of the membrane.", "To differentiate between these possibilities 2 μM 6His-SP1 was applied, and shortly after the onset of membrane depolarization, 4 μM GNPs was applied to the bathing solution ( FIGS. 2E and 2F , n=6).", "Application of GNPs (4 μM) to the bathing solution after the onset of 6His-SP1-induced depolarization, resulting in partial recovery of the input resistance and the transmembrane voltage, FIGS. 2E and 2F .", "In all experiments it was found that the addition of GNPs reversed the initial effects of 6His-SP1 on the membrane potential and Rin.", "The effectiveness of GNPs application revealed large variability ranging from mild improvement to complete recovery.", "On average, following the application of the GNPs the membrane potential was hyperpolarized by 17.33±3.19 mV (n=6) within 10 minutes of GNPs application, whereas Rin recovered by GNP application to 91±14% of the initial value.", "These results are consistent with the hypothesis that the GNP binds to 6His-SP1 that was incorporated into the plasma membrane and reduces the 6His-SP1 pore conductance.", "To address potential nonspecific effects of the GNPs on the membrane ion conductance, GNPs were applied to neurons pre-incubated with wtSP1 ( FIGS. 2G and H).", "The effects of GNPs on the resting potential and input resistances are expressed only when 6His-SP1 is incorporated into the plasma membrane.", "Thus, when wtSP1 is applied to the bathing solution and exerts its effects, application of 4 μM GNPs is ineffective in terms of reversing the effects of SP1 on membrane potential and the input resistance ( FIGS. 2H and 2G ).", "Under these conditions, GNPs application led to 4±1.08 mV membrane hyperpolaryzation (n=4), a significantly smaller hyperpolaryzation than that produced by application of GNPs to 6His-SP1 treated neurons (p<0.05, independent samples t-test).", "Rin did not recover following GNPs application to a wtSP1 treated neuron (remained at 33±10% relative to the initial values, n=4).", "Without wishing to be bound by theory, these results indicate that the recovery of the membrane potential and Rin by the GNPs following 6His-SP1 application is the outcome of specific clogging of the 6His-SP1 inner pore by the applied GNPs ( FIG. 3 )." ]
TECHNICAL FIELD The present invention relates to a method of manufacturing a semiconductor device comprising low resistance cobalt disilicide films. The invention has particular applicability in manufacturing ultra-large scale integration and high density semiconductor devices with submicron design features. BACKGROUND ART The escalating requirements for high densification and performance associated with ultra-large scale integration semiconductor devices requires design features of 0.25 microns and under, increased transistor and circuit speeds, high reliability and increased manufacturing throughput. Such requirements have been found difficult to satisfy in terms of providing low RC (Resistance Capacitance) interconnect patterns. Moreover, as design features are reduced to about 0.25 microns and under, processing defects which were either not apparent or of little impact on device performance become apparent and/or adversely impact device performance, thereby generating an unacceptable rejection rate. Conventional semiconductor manufacturing methodology comprises forming low resistance cobalt disilicide (CoSi 2 ) layers at electrical interconnection points, such as on polycrystalline silicon gate electrodes and/or source/drain regions formed in a silicon semiconductor substrate. Typically, a layer of cobalt is deposited, as by physical vapor deposition (PVD) on the gate electrode and/or source/drain regions. A capping layer containing titanium is then deposited on the cobalt layers to prevent oxygen in the atmosphere from diffusing into the cobalt disilicide layer during the silicidation reaction, thereby preventing an undesirable increase in resistivity. Annealing is then conducted at an elevated temperature during which silicidation occurs, i.e., cobalt reacts with the underlying silicon to form a CoSi 2 low resistivity layer. The titanium-containing capping layer is then removed. It was found, however, that titanium from the capping layer undesirably reacts with cobalt in the underlying layer and diffuses into the silicide layer forming a mixed layer of titanium disilicide (TiSi 2 ) and CoSi 2 having an undesirable high resistivity. In addition, it was found extremely difficult to selectively remove the titanium-containing capping layer without adversely impacting the underlying silicide layer. Accordingly, there exists a need for semiconductor methodology to form low resistivity CoSi 2 layers, particularly in manufacturing ultra-large scale integration and high density semiconductor devices with submicron design features, e.g., 0.25 microns and under. DISCLOSURE OF THE INVENTION An object of the present invention is a method of manufacturing a semiconductor device having submicron features with low resistivity CoSi 2 films on silicon layers. Additional objects and advantages and other features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from the practice of the invention. The objects and advantages of the invention may be realized and obtained as particularly pointed out to the appended claims. According to the present invention, the foregoing and other objects are achieved in part by a method of manufacturing a semiconductor device, the method comprising: forming a substantially cobalt layer on a silicon layer and/or silicon substrate; forming a substantially tungsten nitride layer on each cobalt layer ; annealing while the tungsten nitride layer is on each cobalt layer, to react cobalt in the cobalt layer with the underlying silicon to form a layer of cobalt silicide on the silicon layer and/or substrate. Another aspect of the present invention is a method of manufacturing a semiconductor device, the method comprising: depositing a substantially cobalt layer on a gate electrode comprising silicon and/or on source/drain regions in a semiconductor substrate comprising silicon, at a thickness of about 50 Å to about 250 Å; depositing a substantially tungsten nitride layer on each cobalt layer at a thickness of about 300 Å to about 1500 Å; annealing, while the tungsten nitride is on each cobalt layer, at a temperature of about 450° C. to about 600° C. to form a substantially cobalt monosilicide (CoSi) layer at a thickness of about 200 Å to about 400 Å consuming about 2% to about 10% by weight of the cobalt in the cobalt layer, leaving a layer of unreacted cobalt; removing the tungsten nitride layer; removing the layer of unreacted cobalt; and annealing at temperature of about 700° C. to about 900° C. to convert the layer of CoSi to a layer of cobalt disilicide (CoSi 2 ) having a thickness of about 200 Å to about 900 Å. Additional objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only the preferred embodiment of the invention is shown and described simply by way of illustration of the best mode contemplated for carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the description is to be regarded as a illustrative in nature and not as restrictive. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1-4 schematically illustrate sequential phases of a method in accordance with an embodiment of the present invention. DESCRIPTION OF THE INVENTION The present invention addresses and solves problems attendant upon conventional semiconductor manufacturing methodology in forming CoSi 2 layers employing a capping layer comprising titanium, such as a capping layer of substantially titanium or a titanium alloy. It was found that titanium in the capping layer undesirably reacts with cobalt in the underlying cobalt layer and diffuses into the silicon layer, thereby resulting in a silicide layer comprising both CoSi 2 and TiSi 2 having an undesirably high resistivity. In addition, it is extremely difficult to selectively remove the titanium-containing capping layer without adversely impacting the underlying silicide layer. The present invention addresses and solves such problems by employing a tungsten nitride (WN) capping layer. It was found that during silicidation annealing of the cobalt layer to form cobalt silicide, the WN layer is substantially inert to the silicidation reaction, in that there is substantially no interaction between tungsten and cobalt or between tungsten and cobalt silicide. Moreover, it was found that the WN layer advantageously functions as a diffusion barrier against oxygen diffusing from the annealing ambient into the silicidation region. Consequently, the resulting CoSi 2 layer exhibits a lower resistivity than CoSi 2 layers formed by conventional methods employing a titanium-containing capping layer during the silicidation reaction. It was also found that subsequent to silicidation, the WN capping layer can be easily selectively stripped employing a hydrogen peroxide solution. Embodiments of the present invention include depositing the cobalt layer on a polycrystalline silicon gate electrode and/or source/drain regions in a silicon semiconductor substrate by PVD. The cobalt layer can be deposited at a suitable thickness for forming the low resistivity cobalt CoSi 2 layer, such as at about 50 Å to about 250 Å, e.g., about 100 Å to about 200 Å. The WN layer can be advantageously be deposited by PVD or chemical vapor deposition (CVD) on each cobalt layer at a thickness of about 300 Å to about 1500 Å, e.g., about 700 Å to about 1200 Å. The CoSi 2 layers formed in accordance with embodiments of the present invention typically exhibit a resistivity of about 15 to about 18 micro ohms per centimeter; whereas, CoSi 2 layers formed in accordance with conventional practices employing a titanium-containing capping layer typically have a higher resistivity of about 18 to about 20 micro ohms per centimeter. Embodiments of the present invention comprise depositing the WN layer and then conducting an initial rapid thermal annealing to convert a portion of the deposited cobalt layer e.g., about 2 to about 10 weight percent, into a cobalt monosilicide (CoSi) layer. Such an initial rapid thermal annealing can be conducted for about 1 minute at a temperature of about 450° C. to about 600° C. in an atmosphere containing an inert gas and/or nitrogen, thereby resulting in a CoSi layer having a thickness of about 200 Å to about 400 Å. Subsequently, the layer of WN is selectively removed, as by employing a mixture of hydrogen peroxide, ammonium hydroxide and deionized water, at a volume ratio of about 1:1:5. After selective removal of the WN layer, the remaining unreacted layer of cobalt is removed, as by employing a mixture of hydrogen peroxide and sulfuric acid having concentrations of about 1% and 6.8%, respectively. Subsequently, a second rapid thermal annealing is conducted to convert the high resistivity CoSi layer into a low resistivity CoSi 2 layer. The second rapid thermal annealing to form CoSi 2 can be conducted at a temperature of about 700° C. to about 900° C. for up to about 1 minute in an atmosphere containing an inert gas and/or nitrogen. Typically, the resulting layer of CoSi 2 has thickness of about 200 Å to about 900 Å, e.g., about 350 Å to about 700 Å. An embodiment of the present invention is schematically illustrated in FIGS. 1-4, wherein similar features bear similar reference numerals. Adverting to FIG. 1, a transistor portion of a semiconductor device is schematically illustrated and comprises substrate 10, typically of doped monocrystalline silicon, with source/drain regions 11 formed in a main surface thereof spaced apart to define a channel region. Gate electrode 12, typically doped polycrystalline silicon, is formed above the channel region with a gate oxide layer 13 therebetween. Adverting to FIG. 2, cobalt layer 20 is deposited on source/drain regions 11 and gate electrode 12, as by PVD, at a thickness of about 50 Å to about 250 Å, e.g., 100 Å to about 200 Å. A WN layer 21 is then deposited on each cobalt layer 20, as by PVD or CVD, at a thickness of about 300 Å to about 1500 Å, e.g., about 700 Å to about 1200 Å. With reference to FIG. 3, an initial rapid thermal annealing is then conducted, as at a temperature of about 450° C. to about 600° C., to form a CoSi layer 30, consuming up to about 10% by weight of cobalt layer 20 (FIG. 2) leaving a layer 20A of unreacted cobalt. Subsequently, WN layer 21 is removed, typically employing a mixture of hydrogen peroxide, ammonium hydroxide and deionized water. After removing, the WN layer, unreacted cobalt layer 20A is removed, as by employing mixture of hydrogen peroxide (1% concentration) and sulfuric acid (6.8% concentration). After removing WN layer 21 and unreacted cobalt layer 20A, a second rapid thermal annealing is conducted, as at a temperature of about 700° C. to about 900° C., to convert high resistivity CoSi layer 30 into low resistivity CoSi 2 layer 40, as shown in FIG. 4. Low resistivity CoSi 2 layer typically has a thickness of 300 Å to about 1500 Å, e.g., 700 Å to about 1200 Å. The methodology of the present invention employing a WN capping layer enables the formation of relatively low resistivity CoSi 2 layers having a resistivity of about 15 to about 18 micro ohms per centimeter without encountering the disadvantages attended upon conventional practices employing a titanium-containing capping layer, which results in CoSi 2 layers having an undesirably high resistivity of about 18 to about 20 micro ohms per centimeter. Moreover, the use of a WN capping layer in accordance with embodiments of the present invention avoids any substantial interaction with the underlying cobalt or silicon layer, as occurs when employing a conventional titanium-containing capping layer, and further prevents the diffusion of any oxygen from the annealing ambient into the silicidation region. In embodiments of the present invention, the WN capping layer can be selectively and easily stripped employing a hydrogen peroxide solution. The present invention enjoys utility in manufacturing of various types of the semiconductor devices, particularly high density, multi-metal patterned layers with submicron features, particularly submicron features of 0.25 microns and below. Semiconductor devices produced in accordance with the present invention exhibit high speed characteristics and improved reliability. In the previous descriptions, numerous specific details are set forth in order to provide a through understanding of the present invention. However, the invention can be practiced without resorting to the details specifically set forth. In other instances, well known processing structures have not been described in detail in order not to unnecessarily obscure the present invention. Only the preferred embodiment of the present invention and an example of its versatility are shown and described in the present disclosure. It is to be understood that the invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein.
A substantially inert capping layer of tungsten nitride is deposited on cobalt layers prior to silicidation, thereby avoiding any substantial interaction with cobalt. The tungsten nitride capping layer also functions as a diffusion barrier preventing oxygen from reaching the silicidation area. The resulting cobalt silicides layer exhibit lower resistivity than those formed employing a titanium capping layer. Embodiments include rapid thermal annealing to initially form a layer of cobalt monosilicide consuming a portion of the cobalt layer, removing the tungsten nitride and unreacted cobalt layer, and rapid thermal annealing again to convert the cobalt monosilicide layer to a low resistivity layer of cobalt disilicide.
Summarize the information, clearly outlining the challenges and proposed solutions.
[ "TECHNICAL FIELD The present invention relates to a method of manufacturing a semiconductor device comprising low resistance cobalt disilicide films.", "The invention has particular applicability in manufacturing ultra-large scale integration and high density semiconductor devices with submicron design features.", "BACKGROUND ART The escalating requirements for high densification and performance associated with ultra-large scale integration semiconductor devices requires design features of 0.25 microns and under, increased transistor and circuit speeds, high reliability and increased manufacturing throughput.", "Such requirements have been found difficult to satisfy in terms of providing low RC (Resistance Capacitance) interconnect patterns.", "Moreover, as design features are reduced to about 0.25 microns and under, processing defects which were either not apparent or of little impact on device performance become apparent and/or adversely impact device performance, thereby generating an unacceptable rejection rate.", "Conventional semiconductor manufacturing methodology comprises forming low resistance cobalt disilicide (CoSi 2 ) layers at electrical interconnection points, such as on polycrystalline silicon gate electrodes and/or source/drain regions formed in a silicon semiconductor substrate.", "Typically, a layer of cobalt is deposited, as by physical vapor deposition (PVD) on the gate electrode and/or source/drain regions.", "A capping layer containing titanium is then deposited on the cobalt layers to prevent oxygen in the atmosphere from diffusing into the cobalt disilicide layer during the silicidation reaction, thereby preventing an undesirable increase in resistivity.", "Annealing is then conducted at an elevated temperature during which silicidation occurs, i.e., cobalt reacts with the underlying silicon to form a CoSi 2 low resistivity layer.", "The titanium-containing capping layer is then removed.", "It was found, however, that titanium from the capping layer undesirably reacts with cobalt in the underlying layer and diffuses into the silicide layer forming a mixed layer of titanium disilicide (TiSi 2 ) and CoSi 2 having an undesirable high resistivity.", "In addition, it was found extremely difficult to selectively remove the titanium-containing capping layer without adversely impacting the underlying silicide layer.", "Accordingly, there exists a need for semiconductor methodology to form low resistivity CoSi 2 layers, particularly in manufacturing ultra-large scale integration and high density semiconductor devices with submicron design features, e.g., 0.25 microns and under.", "DISCLOSURE OF THE INVENTION An object of the present invention is a method of manufacturing a semiconductor device having submicron features with low resistivity CoSi 2 films on silicon layers.", "Additional objects and advantages and other features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from the practice of the invention.", "The objects and advantages of the invention may be realized and obtained as particularly pointed out to the appended claims.", "According to the present invention, the foregoing and other objects are achieved in part by a method of manufacturing a semiconductor device, the method comprising: forming a substantially cobalt layer on a silicon layer and/or silicon substrate;", "forming a substantially tungsten nitride layer on each cobalt layer ;", "annealing while the tungsten nitride layer is on each cobalt layer, to react cobalt in the cobalt layer with the underlying silicon to form a layer of cobalt silicide on the silicon layer and/or substrate.", "Another aspect of the present invention is a method of manufacturing a semiconductor device, the method comprising: depositing a substantially cobalt layer on a gate electrode comprising silicon and/or on source/drain regions in a semiconductor substrate comprising silicon, at a thickness of about 50 Å to about 250 Å;", "depositing a substantially tungsten nitride layer on each cobalt layer at a thickness of about 300 Å to about 1500 Å;", "annealing, while the tungsten nitride is on each cobalt layer, at a temperature of about 450° C. to about 600° C. to form a substantially cobalt monosilicide (CoSi) layer at a thickness of about 200 Å to about 400 Å consuming about 2% to about 10% by weight of the cobalt in the cobalt layer, leaving a layer of unreacted cobalt;", "removing the tungsten nitride layer;", "removing the layer of unreacted cobalt;", "and annealing at temperature of about 700° C. to about 900° C. to convert the layer of CoSi to a layer of cobalt disilicide (CoSi 2 ) having a thickness of about 200 Å to about 900 Å.", "Additional objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only the preferred embodiment of the invention is shown and described simply by way of illustration of the best mode contemplated for carrying out the invention.", "As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention.", "Accordingly, the description is to be regarded as a illustrative in nature and not as restrictive.", "BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1-4 schematically illustrate sequential phases of a method in accordance with an embodiment of the present invention.", "DESCRIPTION OF THE INVENTION The present invention addresses and solves problems attendant upon conventional semiconductor manufacturing methodology in forming CoSi 2 layers employing a capping layer comprising titanium, such as a capping layer of substantially titanium or a titanium alloy.", "It was found that titanium in the capping layer undesirably reacts with cobalt in the underlying cobalt layer and diffuses into the silicon layer, thereby resulting in a silicide layer comprising both CoSi 2 and TiSi 2 having an undesirably high resistivity.", "In addition, it is extremely difficult to selectively remove the titanium-containing capping layer without adversely impacting the underlying silicide layer.", "The present invention addresses and solves such problems by employing a tungsten nitride (WN) capping layer.", "It was found that during silicidation annealing of the cobalt layer to form cobalt silicide, the WN layer is substantially inert to the silicidation reaction, in that there is substantially no interaction between tungsten and cobalt or between tungsten and cobalt silicide.", "Moreover, it was found that the WN layer advantageously functions as a diffusion barrier against oxygen diffusing from the annealing ambient into the silicidation region.", "Consequently, the resulting CoSi 2 layer exhibits a lower resistivity than CoSi 2 layers formed by conventional methods employing a titanium-containing capping layer during the silicidation reaction.", "It was also found that subsequent to silicidation, the WN capping layer can be easily selectively stripped employing a hydrogen peroxide solution.", "Embodiments of the present invention include depositing the cobalt layer on a polycrystalline silicon gate electrode and/or source/drain regions in a silicon semiconductor substrate by PVD.", "The cobalt layer can be deposited at a suitable thickness for forming the low resistivity cobalt CoSi 2 layer, such as at about 50 Å to about 250 Å, e.g., about 100 Å to about 200 Å.", "The WN layer can be advantageously be deposited by PVD or chemical vapor deposition (CVD) on each cobalt layer at a thickness of about 300 Å to about 1500 Å, e.g., about 700 Å to about 1200 Å.", "The CoSi 2 layers formed in accordance with embodiments of the present invention typically exhibit a resistivity of about 15 to about 18 micro ohms per centimeter;", "whereas, CoSi 2 layers formed in accordance with conventional practices employing a titanium-containing capping layer typically have a higher resistivity of about 18 to about 20 micro ohms per centimeter.", "Embodiments of the present invention comprise depositing the WN layer and then conducting an initial rapid thermal annealing to convert a portion of the deposited cobalt layer e.g., about 2 to about 10 weight percent, into a cobalt monosilicide (CoSi) layer.", "Such an initial rapid thermal annealing can be conducted for about 1 minute at a temperature of about 450° C. to about 600° C. in an atmosphere containing an inert gas and/or nitrogen, thereby resulting in a CoSi layer having a thickness of about 200 Å to about 400 Å.", "Subsequently, the layer of WN is selectively removed, as by employing a mixture of hydrogen peroxide, ammonium hydroxide and deionized water, at a volume ratio of about 1:1:5.", "After selective removal of the WN layer, the remaining unreacted layer of cobalt is removed, as by employing a mixture of hydrogen peroxide and sulfuric acid having concentrations of about 1% and 6.8%, respectively.", "Subsequently, a second rapid thermal annealing is conducted to convert the high resistivity CoSi layer into a low resistivity CoSi 2 layer.", "The second rapid thermal annealing to form CoSi 2 can be conducted at a temperature of about 700° C. to about 900° C. for up to about 1 minute in an atmosphere containing an inert gas and/or nitrogen.", "Typically, the resulting layer of CoSi 2 has thickness of about 200 Å to about 900 Å, e.g., about 350 Å to about 700 Å.", "An embodiment of the present invention is schematically illustrated in FIGS. 1-4, wherein similar features bear similar reference numerals.", "Adverting to FIG. 1, a transistor portion of a semiconductor device is schematically illustrated and comprises substrate 10, typically of doped monocrystalline silicon, with source/drain regions 11 formed in a main surface thereof spaced apart to define a channel region.", "Gate electrode 12, typically doped polycrystalline silicon, is formed above the channel region with a gate oxide layer 13 therebetween.", "Adverting to FIG. 2, cobalt layer 20 is deposited on source/drain regions 11 and gate electrode 12, as by PVD, at a thickness of about 50 Å to about 250 Å, e.g., 100 Å to about 200 Å.", "A WN layer 21 is then deposited on each cobalt layer 20, as by PVD or CVD, at a thickness of about 300 Å to about 1500 Å, e.g., about 700 Å to about 1200 Å.", "With reference to FIG. 3, an initial rapid thermal annealing is then conducted, as at a temperature of about 450° C. to about 600° C., to form a CoSi layer 30, consuming up to about 10% by weight of cobalt layer 20 (FIG.", "2) leaving a layer 20A of unreacted cobalt.", "Subsequently, WN layer 21 is removed, typically employing a mixture of hydrogen peroxide, ammonium hydroxide and deionized water.", "After removing, the WN layer, unreacted cobalt layer 20A is removed, as by employing mixture of hydrogen peroxide (1% concentration) and sulfuric acid (6.8% concentration).", "After removing WN layer 21 and unreacted cobalt layer 20A, a second rapid thermal annealing is conducted, as at a temperature of about 700° C. to about 900° C., to convert high resistivity CoSi layer 30 into low resistivity CoSi 2 layer 40, as shown in FIG. 4. Low resistivity CoSi 2 layer typically has a thickness of 300 Å to about 1500 Å, e.g., 700 Å to about 1200 Å.", "The methodology of the present invention employing a WN capping layer enables the formation of relatively low resistivity CoSi 2 layers having a resistivity of about 15 to about 18 micro ohms per centimeter without encountering the disadvantages attended upon conventional practices employing a titanium-containing capping layer, which results in CoSi 2 layers having an undesirably high resistivity of about 18 to about 20 micro ohms per centimeter.", "Moreover, the use of a WN capping layer in accordance with embodiments of the present invention avoids any substantial interaction with the underlying cobalt or silicon layer, as occurs when employing a conventional titanium-containing capping layer, and further prevents the diffusion of any oxygen from the annealing ambient into the silicidation region.", "In embodiments of the present invention, the WN capping layer can be selectively and easily stripped employing a hydrogen peroxide solution.", "The present invention enjoys utility in manufacturing of various types of the semiconductor devices, particularly high density, multi-metal patterned layers with submicron features, particularly submicron features of 0.25 microns and below.", "Semiconductor devices produced in accordance with the present invention exhibit high speed characteristics and improved reliability.", "In the previous descriptions, numerous specific details are set forth in order to provide a through understanding of the present invention.", "However, the invention can be practiced without resorting to the details specifically set forth.", "In other instances, well known processing structures have not been described in detail in order not to unnecessarily obscure the present invention.", "Only the preferred embodiment of the present invention and an example of its versatility are shown and described in the present disclosure.", "It is to be understood that the invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein." ]
CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/998,714 filed on Jul. 7, 2014. FIELD OF THE INVENTION The present invention relates to antenna assemblies and systems for wireless electronic devices. BACKGROUND OF THE INVENTION Conventional antenna systems utilizing, for example, wire, PIFA, resonant loop, chip, patch, stripline antennas and other similar traditional antenna configurations have, in the past, limited the functionality of wireless electronic devices due to power loss resulting from inefficiencies, and associated limitations on bandwidth and gain, coupling and detuning antenna impedance/resonance and other limitations perpetuated by antenna systems conventionally employed. A particular issue with such conventional antenna assemblies arises from antenna coupling with surrounding or adjacent surfaces adversely impacting radiation pattern and input match associated with use of a conventional open body antenna. Such coupling and detuning issues impose design limitations for attaining acceptable reception, resulting from, among other things, gain and bandwidth for radio frequency signals received and transmitted to the device. As a result, design configurations for wireless electronic devices providing the requisite physical size, radiation pattern, bandwidth and gain specifications facilitating optimal functionality for electronic devices fed thereby have heretofore been restricted by such limitations. Despite attempts to address such limitations and problems, for example, by reconfiguring antenna designs, and integration of shield components to prevent coupling and detuning of signal inputs and transmissions in conventional antenna systems, a need to solve such and other limitations and issues persist. Conventional waveguide antennas typically employing one or more slotted input arrays have, in the past, been utilized in large scale equipment, including navigation and radar systems for aircraft and backhaul transmission systems. Such large bulky waveguide antennas have not been well suited to small electronic devices. Conventional waveguides utilized in such systems are conventionally cylindrical coaxial cables which operate in the dominant TEM mode and employ multiple apertures spaced along the waveguide guide length at particular intervals. Although such known waveguide antenna systems address issues with coupling and detuning, size and shapes limitations have precluded their adaptation to many wireless electronic devices, which are becoming increasingly more compact. Size and such other limitations of conventional waveguide geometric configurations, as well as patterns or modes associated with conventional waveguide antennas have stymied integration of waveguide antenna systems in many electronic devices, including but not limited to personal or consumer electronic devices such as, for example, mobile smartphones, smartwatches, MP3 players, wearable electronics and other such devices. The present invention as described below provides solutions and design alternatives addressing such limitations and drawbacks of the prior art. SUMMARY OF THE INVENTION The present invention addresses such limitations and drawback of the prior art by providing a waveguide antenna assembly and process which is conformable to an electronic device supported thereby. The waveguide antenna for transceiving signals of a predetermined radio frequency range comprising a first conductive layer configured in a conformable loop, wherein the first conductive layer has an inner surface and an outer surface, the inner surface and outer surface having an area coextensively disposed between an outer edge and an opposing inner edge; a second conductive layer configured in a conformable loop, having of an area coextensively disposed between an outer edge and an opposing inner edge, wherein the second conductive layer is collaterally aligned with the inner surface of the first conductive layer so as to electrically isolate the second conductive layer from the first conductive layer for support of waveguide modes of the predetermined frequency range; an electrically isolating channel extending between the inner surface of the first conductive layer and the second conductive layer, wherein the electrically isolating channel is dimensionally configured for transmission of the waveguide modes of the predetermined frequency range; an aperture for electromagnetically transceiving the signals, wherein the aperture is coextensively overlayed on a surface of the electrically isolating channel such that opposing sides of the aperture extend between the outer edge of the inner surface of the first conductive layer and the second conductive layer; a back short spaced back from the aperture a predetermined distance equal to a resonant length of the waveguide mode wavelength, wherein the back short provides a circuit impedance between the first conductive layer and the second conductive layer for tuning the waveguide to transceive the signals; and at least one excitation point coupled to the aperture to propagate waveguide modes within the electrically isolating channel. In a particularly preferred embodiment of this waveguide antenna assembly, the excitation points are provided as quadrature excitation points in orthogonal orientation within the waveguide. Embodiments of the present invention further provide excitation points configured within the waveguide so as to sequentially electromagnetically shift the phase of the signals of a predetermined frequency range to cause rotational polarization. The excitation points may be amplitude and phase coupled to switch the waveguide mode pattern to steer the antenna gain pattern from a broadside to a bore sight direction. In an alternative embodiment of this waveguide, the back short is adjustably mounted for providing a circuit impedance in the range of between one-eighth waveguide mode wavelength and one-half of a waveguide mode wavelength of the signals of the predetermined radio frequency range. In a particularly preferred embodiment, the back short is spaced back from the aperture one-quarter of the waveguide mode wavelength of the signals of the predetermined radio frequency range. In preferred embodiments of the present invention, the back short is set at a resonant length whereby the waveguide modes are nonevanescent. The waveguide antenna according to the present invention contemplates operating in signal radio frequency bandwidths of between 1 Hz and 1 THz. As further described below, the conformability of the present waveguide's conductive layer imparts adaptability to diverse shapes and sizes and physical configurations wherein they may be fitted within, around or on variously shaped electronic devices supported thereby. Such conformability enables adaptability to underlying device package redesigns without compromising specification-compliant performance, particularly within physical confines of small and compact modern devices, comprises one of many advantages provided by the present waveguide assembly and process. Exemplary geometric configurations, as further described below, include waveguide antenna assemblies which encompass, embed or attach to an electronic device coated by a nonconductive, polymeric material. Types of electronic device which the present invention may support are as varied as its potential configurations, and include any processor-based systems. In particular, devices the present antenna design supports include smartphones, smartwatches and other wearable technology and any devices including GPS or for digitally streaming and broadcasting signals to mobile or desk top systems, including computers and televisions. The present invention further provides an underlying process for transceiving of data signals to and from an electronic device supported thereby through a waveguide, comprising transceiving signals of the predetermined frequency range to and from an aperture oriented in a continuous elongated loop formed between conductive layers, wherein the aperture extends into a nonconductive channel so as to electrically isolate the conductive layers to dimensionally support waveguide modes for multimodal transmission and radiation of the signals of a predetermined frequency range, providing a circuit impedance between the two conductive layers for tuning the waveguide mode resonance to form waveguide mode radiation patterns, the circuit impedance of a back short spaced back a corresponding resonant length of the waveguide mode, electromagnetically coupling the signals of a predetermined frequency range to the aperture, by coupling at least one excitation point so as to propagate waveguide mode patterns within the waveguide, and feeding the signals of the predetermined radio frequency range to and from the electronic device supported by the waveguide. Reflecting counterpart elements of the assembly, the process further comprises sequentially electromagnetically shifting the waveguide modes to rotationally polarize antenna aperture fields. The process enables varying the amplitude and phase coupling of the excitation points to vary waveguide modes and thereby steer antenna gain patterns. A process according to the present invention may further comprise steps of encasing an electronic device within the interior of the waveguide assembly or, alternatively, embedding the waveguide antenna in a nonconductive material extending about the electronic device supported thereby. A particularly preferred embodiment of the present invention comprises a coaxially disposed inner electrically conductive layer and an outer electrically conductive layer disposed some radial distance about the inner conductive layer, an isolating channel, nonconductive medium, interspersed therebetween and a resonant aperture on the outer electromagnetic interface coextensive with the outer surface of the isolating channel lying between collateral sides of the outer electrically conductive layer circumference and the inner electrically conductive layer outer edges. As depicted in the drawings and further specified in the detailed description of the preferred embodiments below, the waveguide comprises conformably looped collaterally, or side-by-side, oriented inner and outer electrically conductive layers form the perimeters of an open ended resonant cavity coextensively interfacing with an electromagnetic aperture formed between respective inner perimeters of the outer conductive layer and the inner conductive layer, a back short spaced apart a resonant distance from the electromagnetic aperture, wherein, and orthogonal excitation points are then strategically oriented in relation to the resonant cavity and set to an amplitude and phase to excite and polarize radio frequency signals received and transmitted through an electromagnetic aperture, thereby propagating waveguide modes. As described and claimed herein, the waveguide system and process of the present invention enables excitation and polarization for redirection of antenna radiation patterns, which is commonly known in the art and referred to herein as beam steering, with a single antenna and aperture opening. According to the present waveguide antenna system, the inner conductive layer and the outer conductive layer are dimensionally configured to support nonevanescent waveguide modes where the mode resonator is set by spacing the back short from the aperture a resonant length of the nonevanescent waveguide mode wavelength of the signals of the predetermined radio frequency range. To thus provide nonevanescent waveguide modes, the back short sets a reference point in the waveguide resonator such that mode fields are stable along the waveguide propagation direction, being at maximum for a mode in the aperture and the excitation point sets the waveguide mode for the resultant aperture field radiation pattern established. Thus, the isolating medium occupies the waveguide space that is bounded by the outer and inner conductive layers, and back short conductors. In this medium, the waveguide mode resonates and the dominant resonant mode is established by the manner in which the resonant cavity is excited at the feed points. In alternative embodiments, the resonant cavity between aperture and back short may be tuned to variable waveguide frequencies. In a particularly preferred embodiment, the resonant longitude distance of the resonant cavity between the aperture and the back short is equal to one quarter waveguide wavelength. Components of this invention including the-back short, electronically conductive layers, excitation points and isolating medium may comprise material known in the relevant art to be functional or suitable for the stated purpose. For example, conductive layers may comprise copper, metal alloys or other well know conductors utilized in prior art antennas, excitation point may employ a printed circuit board (PCB) or microstrip coupling, direct terminals, magnetic loops, or other suitable waveguide launch mechanisms. Suitable nonconductive materials to fill the isolating medium include any matter exhibiting low dielectric losses. As further alluded to herein, the overall or outer shape of the present waveguide antenna assembly may comprise any geometric configuration which supports aperture field formation and nonevanescent waveguide modes, as described further herein. Alternative embodiments may implement shapes that are not radially or cylindrically disposed, such as square, triangular, rectangular or nonsymmetrical or any structure, symmetric or arbitrary capable of supporting nonevanescent multimode behavior. Preferred embodiments of the present waveguide antenna are adapted to optimize the aesthetic look and functionality relating to the physical and electronic configuration of a corresponding electronic device in which it is integrated. Preferred embodiments of the present waveguide antenna assembly further comprise geometric configurations conforming to and enclosing in body, the outer surface of a wireless device. A further preferred embodiment of the present waveguide system strategically orients the continuous aperture to avoid coupling with an electronic device and thereby detuning the antenna. In a preferred embodiment of the present invention enabling this feature, the aperture is oriented in a continuous loop contiguously channeled inside the entire outer conductor perimeter. Particularly preferred embodiments electronically couple the resonant radio frequencies received and transmitted by the present assembly with the electromagnetic surface waves native to the electronic device with which it is integrated. Attributes and properties of the present invention provide many advantages over prior art antennas. First, the internal cavity resonator addresses problems related to detuning through coupling with the technology device, so that antenna performance is not impacted, as open resonators (PIFA, loop, etc.) do in compact technology. Second, the present waveguide antenna assembly and system is adaptable to the package surface as an efficient surface wave exciter, allowing previously unused package area (outer surface) to render useful in radiation coverage. Third, the present invention provides a multimode antenna that can be dynamically configured to redirect the antenna radiation pattern or polarization through a combination of precisely excited waveguide modes. Fourth. this invention enables radiation redirection, which is commonly referred to in the art as beam steering, by a single antenna resulting from redirection of the mode(s) formed in a single aperture by the excitation points as specified herein, providing a substantial advantage over arrays of multiple antennas required to redirect radiation patterns in the prior art. Fifth, the multimode reception of the present waveguide antenna assembly and system allows for coherent integration of the one or more excitation points that can be post processed for noise reduction. Sixth, the present waveguide antenna forms an intrinsic EMI barrier, eliminating the need for such shielding. A yet further, seventh, advantage provided by the present invention is the minimal physical size of the antenna allowing for more compact designs of modern electronic device. Such attributes and properties provide many advantages over prior art antennas. An advantage provided by the present invention relates to adaptability of the present waveguide antenna to the exterior surface of an electronic device so as to enhance the resultant radiation pattern. For example, where the electronic device is enclosed in a conductive skin that encompasses a rotational surface (i.e., cylinder, tube, etc.), it is possible to establish surface wave propagation on that conductive skin. In addition, because the natural mode of propagation is similar in field structure to that established by the aperture field, corresponding surface waves are readily excited. Moreover, the adjacent surface of an electronic device may be designed to enhance its interaction with the waveguide antenna to improve those radiation characteristics. Substantial advantages provided by the present waveguide antenna assembly and system derive from its compact and versatile geometric configuration. Such conformable size and shape render it adaptable for incorporation into condensed designs for wireless electronic devices which are small, sleek, ergonomic, turnkey, portable assemblies and readily secured to a relevant wearable or other surface. The present waveguide assembly and system thus delivers enhanced electronic performance within size and configuration confines imposed by such compact electronic devices. These and other advantages and benefits heretofore inadequately addressed and unavailable in the prior art are now provided by the waveguide antenna assembly and system as described, enabled and claimed herein. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustrating an exemplary physical configuration of the inner and outer conductive layers, and isolating medium of the present waveguide antenna. FIG. 2 is a schematic illustrating a perspective view of the back of a particularly preferred embodiment of the assembled waveguide antenna assembly according to the present invention. FIG. 2A is a schematic illustrating perspective view of the front of a particularly preferred embodiment of the assembled waveguide antenna assembly according to the present invention. FIG. 2B is a schematic illustrating a perspective view of the front of a particularly preferred embodiment of the disassembled waveguide antenna assembly according to the present invention. FIG. 2C is a schematic illustrating a cross sectional view along line 2 D- 2 D of FIG. 2 . FIG. 2D is a schematic illustrating a close up view of the circled portion of FIG. 2C labeled SEE 2 D. FIG. 3 is a graphic representation of radially symmetric E and H waveguide mode field lines deployable in the waveguide antenna assembly according to the present invention. FIG. 4 is a schematic of a particularly preferred embodiment of the present invention. FIG. 4A is a graphic representation of simulated principal plane directivity, gain and polarization isolation patterns for the waveguide antenna assembly of the present invention applied to a wearable GPS of a preferred embodiment. FIG. 5 is a schematic of a preferred embodiment of the waveguide assembly and system according to the present invention embedded in an acrylic covered conductive tube of a generally square shape along a transverse axis. FIG. 5A is a graphic representation of simulated principal plane directivity and gain patterns for a TEM/H 11 mode switched waveguide antenna assembly of the present invention. FIG. 6 is a schematic of a preferred embodiment of the waveguide assembly and system according to the present invention embedded in an acrylic covered conductive tube of a generally rectangular shape. FIG. 6A is a graphic representation of simulated principal plane directivity and gain patterns for a fixed H 11 mode waveguide antenna assembly of the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawings, preferred embodiments and operational details of the present waveguide antenna assembly and system are shown and described in detail. In order to more particularly point out and clearly define the presently claimed invention, particularly spatial orientation and electromagnetic correspondence of components of the waveguide assembly, this paragraph defines terms used herein to describe and claim the present invention. To that end, dimensional arrangements are defined along Cartesian longitudinal and transverse axes. Accordingly, as referred to herein, and well known in the relevant art, a longitudinal direction is parallel to the Cartesian Z axis and the transverse direction parallel to the Cartesian X-Y axis. As illustrated, the X-axis is disposed in a horizontal transverse direction and the Y-axis is disposed in a vertical transverse direction. The term “collateral” as used herein defines spatial orientation electrically conductive layers, claimed as a first conductive layer and as a second conductive layer, to comprise side-by-side alignment not limited to a particular or precise parallel, longitudinal or transverse alignment. The collaterally oriented conductive layers are oriented to provide an electrically isolating channel spatially dimensioned to support waveguide modes, which are characterized by corresponding patterns orthogonally depicted along Cartesian axes such as graphically shown in FIG. 3-6A and in the respective detailed descriptions thereof. The term “back short” is used herein to refer to the physical device that presents the terminating waveguide circuit impedance to the waveguide resonator and this can be formed using any mechanical or electrically controlled feature that presents the proper terminating impedance so that a resonant waveguide mode is established in the waveguide. In the preferred embodiment(s) of the present invention, this circuit impedance is a conductive short between the first and second conductive surfaces. Illustrating one of innumerable alternative conformable physical configurations and profiles the present waveguide antenna may embody, FIG. 1 exemplifies one irregularly configured preferred embodiment of the present invention. The latter structure employs a coaxial waveguide 10 comprising an outer, or first, conductive layer 2 and a collateral inner, or second, conductive layer 4 separated by an isolating channel 6 dimensioned to support nonevanescent waveguide modes. Electrically isolating channel 6 may comprise any dielectric or nonconductive medium, and preferably comprises a low loss dielectric material with high permeability, such as, for example, Ba 2 T 19 O 29 or Zr 2 TiO 4 . Alternatively, an isolating medium may comprise any suitable low loss material, including for example, air, a vacuum, a dielectric substrate, or a ceramic substrate. As particularly pointed out in FIG. 1 , waveguide antenna 10 is conformable to fit about an electronic device (not shown) housed within a hollow or open core 8 formed inside of inner conductive layer 4 . Such internal housing of an electronic device within open cavity 8 of waveguide antenna 10 of this preferred embodiment of the present invention, provides multiple advantages. First, the conformable, compact assembly is spatially efficient and may be adapted to constrained, variably configured spaces. Second, nesting an electronic device within waveguide antenna 10 provides a durable, protective shield about the nested electronic device thereby preventing damage from impacts, and wear and tear. Moreover, thus positioning an electronic device within a hollow or open cavity as shown in FIG. 1 overcomes performance problems, such as, detuning, power attenuation, and gain loss issues common to conventional antenna systems and connected electronic devices are juxtapositioned in close proximity. In contrast to requisite redesigns of known antennas in order to comply with relevant specifications of new device designs commonly reducing its size and changing the overall profile and configuration, the waveguide antenna of the present invention may be readily adapted without comparable redesigning. The present waveguide antenna's resistance to performance impediments and concomitant conformability to package redesigns of electronic devices provides substantial improvements over prior art antenna configurations. FIG. 2-2D illustrate a preferred embodiment of the present waveguide antenna assembly 20 comprising a generally square configuration particularly designed for use in the many electronic devices employing GPS. FIG. 2 shows a perspective view from the back of the waveguide antenna assembly 20 showing connectors 28 for feeding data signals to an electronic device through techniques well known in the art. FIG. 2A depicts a frontal perspective view of waveguide assembly 20 showing orientation of excitation points 24 on microstrip PCA 26 , when assembled to cover aperture 12 , which electromagnetically transceives signals of a predetermined frequency range through microstrip PCA 26 . FIG. 2B shows microstrip PCA 26 disassembled from the waveguide antenna assembly 20 to reveal orientation of aperture 12 relative to quadrature orthogonal excitation points 24 . Now referring to FIG. 2B-2D , aperture 12 opens into isolating channel 18 providing an isolating cavity resonator for transmission of waveguide modes from which the impedance of back short 22 is set in connection with quadrature excitation points 24 so as to form nonevanescent waveguide modes. FIGS. 2C and 2D are cross-sectional views of the particularly preferred embodiment of FIG. 2 - FIG. 2B showing a cutaway view taken along line 2 D- 2 D. FIG. 2D provides an exploded view of the area circled in FIG. 2C more clearly depicting the geometric configuration and relative orientation of aspects enabling the electromagnetic synchrony of the present waveguide antenna. As shown in FIGS. 2C and 2D cross sectional views of outer, or first, conductive layer 14 and inner, or second, conductive layer 16 are separated and thereby isolated by electrically isolating channel 18 , which may comprise any dielectric. Electrically isolating channel 18 opens into aperture 12 , which electromagnetically forms aperture fields of the signals of a predetermined radio frequency range through electrical coupling with excitation points 24 that is part of the microstrip PCA 26 with dielectric substrate 23 and reference ground plane 21 and back short 22 , as described below. Aperture 12 is spaced a resonant one quarter waveguide mode wavelength of the corresponding signals of the predetermined radio frequency range from back short 22 , Back short 22 provides a circuit impedance between the first conductive layer and the second conductive layer whereby the waveguide is tuned to the signals of a predetermined frequency range. In the particularly preferred embodiment shown in FIG. 2-2D , each excitation point 24 is individually controlled by dynamic amplitude and phase positioning resulting in waveguide modes which are preferably nonevanescent. Excitation points 24 are phased to establish orthogonal modes which rotate aperture fields either clockwise or counter clockwise. Thus, quadrature excitation points 24 are amplitude and phase coupled so as to alter waveguide modes, thereby steering antenna gain pattern of the radio frequency signals of a predetermined wavelength. As detailed in FIG. 3-6A and respective description thereof, adjusting amplitude and phase rotates the aperture field about a symmetrical longitudinal axis to dynamically control the radiation polarization orientation to a horizontal, vertical or any angle therebetween. Exemplary modes established by arranging field excitations to align with the mode's field pattern are graphically represented in FIG. 3 . Skilled artisans will further recognize the modes graphically shown in FIG. 3 depict a static phase relationship, as utilized in the waveguide of the present invention, wherein excitation points generate field distribution lines forming the illustrated mode patterns. As marked to the right of the respective planes of waveguide mode patterns in FIG. 3 , appropriate order modes are marked, as follows: 1. cross sectional view, 2. longitudinal view, and 3. surface view along a coaxial waveguide from Cartesian axes as defined above and shown in the planes identified by the X, Y, and Z axes as shown in the drawings and referred to herein. Now referring to FIG. 3 , H modes 30 are shown in the left column and E mode patterns 40 are shown on the right column. In particular, H order waveguide mode transverse magnetic field lines 34 A, 34 B, and 34 C respectively depict H 11 , H 21 and H 31 order modes cut along a plane transverse to the direction of propagation. Longitudinal lines 36 A, 36 B, and 36 C depict the same mode patterns for H 11 , H 21 and H 31 order modes cut along longitudinal planes corresponding to respective lines A 3 -A 3 , B 3 -B 3 , C 3 -C 3 in the direction of propagation. Surface patterns 38 A, 38 B and 38 C depict views from points A/A, B/B. and C/C counterpart perspectives of E order waveguide modes 40 field distribution lines which may be harnessed in the waveguide of the present invention are graphically depicted on the right half of FIG. 3 . In particular, transverse magnetic field lines 44 A, 44 B, and 44 C depict the relevant mode patterns transverse to the direction of propagation for E 11 , E 21 , and E 31 order modes respectively while 46 A, 46 B and 46 C illustrate respective longitudinal pattern cut along lines D 3 -D 3 , E 3 -E 3 , and F 3 -F 3 , and patterns 48 A, 48 B, and 48 C depict patterns from points D/D, E/E, and F/F respectively. Modes within the scope of the present invention include, but are not limited to, those shown in FIG. 3 , which are exemplary waveguide mode patterns. Although not included in FIG. 3 , it will be apparent to persons skilled in the art that TEM is supported by the present waveguide assembly. That is, by strategically orienting positive voltage terminals on an electrically conductive layer, which may be inner or outer layers if a coaxial waveguide, relative to diametrically opposing excitation point, resultant excitation electric field strongly couples to the TEM mode, rejecting modes that are not field aligned. In contrast to radially symmetric TEM modes utilized in conventional antenna systems, the strategic orientation and amplitude/phase coordination provided by application of evanescent mode forms as the primary aperture field distribution provides substantial advantages. To demonstrate the dynamic correspondence providing such advantages, the following calculations will make apparent to persons skilled in the relevant art the electromagnetic rotation providing the phase shifting enabled by the present invention. As well known in the art, the waveguide mode with the lowest cutoff frequency is the basic mode of the waveguide, and its cutoff frequency is the waveguide cutoff frequency. Accordingly, the cutoff wavelength for the E and H modes are: λ_ cE≈ 2( a−b )/ n,E —mn modes, m= 0,1, . . . n> 0  (1) λ_ cH ≈π( a+b )/ m,H —m1 modes, m= 1,2,  (2) where a and b are the radial symmetric waveguide inner and outer conductor respective radii. Examination of the guide cutoff wave length(s), show that for large radius and small conductor separation, the probable set of modes is only the H —m1 . Furthermore, those H —m1 modes can be excited by selectively placing excitation points rotationally at: (π( i− 1))/ m,i= 1,2, . . . m+ 1 The present waveguide antenna system uses this arrangement to selectively excite the radially symmetric TEM, or the higher order asymmetric H —m1 modes. FIG. 4 depicts a particularly preferred embodiment of the present waveguide antenna assembly, contemplated as a deployable GPS antenna 50 for small wearable electronic devices, such as a smart watch. The overall geometric configuration of GPS antenna 51 is generally a square measuring 25 mm×25 mm×5 mm high and placed on the body wrist 53 . This embodiment sets excitation points, counterparts of which are shown in FIG. 2 , with equal amplitudes and sequentially phase shifts each by 90 degrees whereby right hand polarization, such as graphically depicted in FIG. 5 , is exhibited. Now referring to FIG. 4A , a graph depicting the radiation pattern conveys how multimode properties of the present waveguide antennae may be implemented to control, or shift, the radiation pattern. In particular, by exciting orthogonal H modes in quadrature phase, the radiation pattern will form an Omni Right Hand Circular Polarization (RHCP) pattern graphed by dashed and dotted line 52 and solid line 54 and suppress the Left Hand Circular Polarization (LHCP) graphed by dotted line 56 and broken dashed and dotted line 58 , and thereby optimize GPS signal reception. As used herein, quadrature phase refers to: excitation of the feeds by sequentially shifting each feed phase by 90 degrees relative to the feed before with equal amplitudes. Referring to FIG. 5 , an alternative preferred embodiment of the present invention is provided in a conductive tube 60 covered by an acrylic or other low loss dielectric wherein a multimode coaxial waveguide antenna 62 is embedded which houses an electronic device. Such a nonconductive or low loss material could comprise, for example, a polymeric material such as an acrylic, an epoxy, a phenolic, baked glass, or ceramic compound. FIG. 5A provides a graphic representation of simulated principal plane directivity and gain patterns for a TEM/H 11 mode switched waveguide antenna assembly of the present invention. The graphic data shown in FIG. 5A demonstrates antenna gain patterns relating to excitation switching, i.e., suppression or enhancement thereof, between the TEM and H 11 modes whereby mode propagation is controlled, that determines the antenna radiation in a bore sight direction along the XZ plane, or along a broadside direction along the YZ plane. Thus, the excitation points may be manipulated to switch from a bore sight to broadside directions or eliminate interference from either direction, which is otherwise known in the art and referred to herein as beam steering. In the latter embodiment, the radiation patterns in the generally square configuration shown in FIG. 5A graphically depict improved gain provided by stable excitation of nonevanescent H 11 /TEM patterns graphically depicted, along the XZ plane of FIG. 5 , as dashed line 64 and dotted line 70 , respectively, and as dashed and dotted line 68 and solid line 66 along the XY plane. FIG. 6 illustrates a further preferred embodiment employing a generally rectangular configuration 80 of the present invention to further exemplify the flexibility of the parameters of potential embodiments of the present invention. In this embodiment, antenna 82 is scaled approximately three times in the Y dimension and half the X dimension (75 mm×12 mm vs 25 mm×25 mm). All other parameters remain the same as in FIG. 5 . FIG. 6A provides a graphic representation of simulated principal plane directivity and gain patterns for a H 11 mode. Corresponding waveguide mode patterns depicted by solid line 84 shows the H 11 mode along the XZ plane and dashed and dotted line 86 shows the H 11 mode along the XY plane. A comparison of FIG. 5A and FIG. 6A demonstrates that substantial modification of antenna dimensions as shown in respective configuration shown in FIG. 5 and FIG. 6 has minimal impact on the antenna performance—XZ plane peak gain @ angle=delta<ldB. Such dimensional conformability of the present waveguide antenna manifests in diverse space allocations and applications, and is particularly advantageous in compact electronic device package redesigns contexts. The present waveguide antenna's stable performance notwithstanding packaging revisions while maintaining provides a substantial advantage of the present waveguide antenna over existing designs wherein package reconfiguration typically requires complete redesign of supporting antenna(s). While a number of exemplary aspects and embodiments have been discussed above, those possessed of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. In particular, this invention embraces waveguides of any shape and size, regardless of symmetry or geometric regularity, wherein dynamic positioning of an aperture in correspondence with a resonant back short and excitation points configured to provide nonevanescent waveguide modes described and claimed herein. Such waveguides are not limited to a coaxial configuration but may comprise any number or combination of conductive layers and resonant cavities. It is therefore intended that the scope of this specification include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.
A waveguide antenna assembly and process for transceiving signals of a predetermined radio frequency range comprising at least two collaterally aligned conductive layers configured in a conformable loop so as to form an electrically isolating channel dimensionally configured for support of the waveguide modes of the predetermined frequency range, an aperture for electromagnetically transceiving the signals, wherein the aperture extends along a surface of the electrically isolating channel such that the aperture extends between the outer edge of the inner surface of the first conductive layer and the second conductive layer, a back short spaced apart from the aperture a predetermined distance equal to a resonant length of the waveguide mode wavelength so as to provide a circuit impedance between the first conductive layer and the second conductive layer for tuning the waveguide to transceive the signals, and excitation points coupled to the aperture to propagate waveguide modes within the electrically isolating channel, which is conformable to the configuration of a supported electronic device.
Briefly outline the background technology and the problem the invention aims to solve.
[ "CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Patent Application Ser.", "No. 61/998,714 filed on Jul. 7, 2014.", "FIELD OF THE INVENTION The present invention relates to antenna assemblies and systems for wireless electronic devices.", "BACKGROUND OF THE INVENTION Conventional antenna systems utilizing, for example, wire, PIFA, resonant loop, chip, patch, stripline antennas and other similar traditional antenna configurations have, in the past, limited the functionality of wireless electronic devices due to power loss resulting from inefficiencies, and associated limitations on bandwidth and gain, coupling and detuning antenna impedance/resonance and other limitations perpetuated by antenna systems conventionally employed.", "A particular issue with such conventional antenna assemblies arises from antenna coupling with surrounding or adjacent surfaces adversely impacting radiation pattern and input match associated with use of a conventional open body antenna.", "Such coupling and detuning issues impose design limitations for attaining acceptable reception, resulting from, among other things, gain and bandwidth for radio frequency signals received and transmitted to the device.", "As a result, design configurations for wireless electronic devices providing the requisite physical size, radiation pattern, bandwidth and gain specifications facilitating optimal functionality for electronic devices fed thereby have heretofore been restricted by such limitations.", "Despite attempts to address such limitations and problems, for example, by reconfiguring antenna designs, and integration of shield components to prevent coupling and detuning of signal inputs and transmissions in conventional antenna systems, a need to solve such and other limitations and issues persist.", "Conventional waveguide antennas typically employing one or more slotted input arrays have, in the past, been utilized in large scale equipment, including navigation and radar systems for aircraft and backhaul transmission systems.", "Such large bulky waveguide antennas have not been well suited to small electronic devices.", "Conventional waveguides utilized in such systems are conventionally cylindrical coaxial cables which operate in the dominant TEM mode and employ multiple apertures spaced along the waveguide guide length at particular intervals.", "Although such known waveguide antenna systems address issues with coupling and detuning, size and shapes limitations have precluded their adaptation to many wireless electronic devices, which are becoming increasingly more compact.", "Size and such other limitations of conventional waveguide geometric configurations, as well as patterns or modes associated with conventional waveguide antennas have stymied integration of waveguide antenna systems in many electronic devices, including but not limited to personal or consumer electronic devices such as, for example, mobile smartphones, smartwatches, MP3 players, wearable electronics and other such devices.", "The present invention as described below provides solutions and design alternatives addressing such limitations and drawbacks of the prior art.", "SUMMARY OF THE INVENTION The present invention addresses such limitations and drawback of the prior art by providing a waveguide antenna assembly and process which is conformable to an electronic device supported thereby.", "The waveguide antenna for transceiving signals of a predetermined radio frequency range comprising a first conductive layer configured in a conformable loop, wherein the first conductive layer has an inner surface and an outer surface, the inner surface and outer surface having an area coextensively disposed between an outer edge and an opposing inner edge;", "a second conductive layer configured in a conformable loop, having of an area coextensively disposed between an outer edge and an opposing inner edge, wherein the second conductive layer is collaterally aligned with the inner surface of the first conductive layer so as to electrically isolate the second conductive layer from the first conductive layer for support of waveguide modes of the predetermined frequency range;", "an electrically isolating channel extending between the inner surface of the first conductive layer and the second conductive layer, wherein the electrically isolating channel is dimensionally configured for transmission of the waveguide modes of the predetermined frequency range;", "an aperture for electromagnetically transceiving the signals, wherein the aperture is coextensively overlayed on a surface of the electrically isolating channel such that opposing sides of the aperture extend between the outer edge of the inner surface of the first conductive layer and the second conductive layer;", "a back short spaced back from the aperture a predetermined distance equal to a resonant length of the waveguide mode wavelength, wherein the back short provides a circuit impedance between the first conductive layer and the second conductive layer for tuning the waveguide to transceive the signals;", "and at least one excitation point coupled to the aperture to propagate waveguide modes within the electrically isolating channel.", "In a particularly preferred embodiment of this waveguide antenna assembly, the excitation points are provided as quadrature excitation points in orthogonal orientation within the waveguide.", "Embodiments of the present invention further provide excitation points configured within the waveguide so as to sequentially electromagnetically shift the phase of the signals of a predetermined frequency range to cause rotational polarization.", "The excitation points may be amplitude and phase coupled to switch the waveguide mode pattern to steer the antenna gain pattern from a broadside to a bore sight direction.", "In an alternative embodiment of this waveguide, the back short is adjustably mounted for providing a circuit impedance in the range of between one-eighth waveguide mode wavelength and one-half of a waveguide mode wavelength of the signals of the predetermined radio frequency range.", "In a particularly preferred embodiment, the back short is spaced back from the aperture one-quarter of the waveguide mode wavelength of the signals of the predetermined radio frequency range.", "In preferred embodiments of the present invention, the back short is set at a resonant length whereby the waveguide modes are nonevanescent.", "The waveguide antenna according to the present invention contemplates operating in signal radio frequency bandwidths of between 1 Hz and 1 THz.", "As further described below, the conformability of the present waveguide's conductive layer imparts adaptability to diverse shapes and sizes and physical configurations wherein they may be fitted within, around or on variously shaped electronic devices supported thereby.", "Such conformability enables adaptability to underlying device package redesigns without compromising specification-compliant performance, particularly within physical confines of small and compact modern devices, comprises one of many advantages provided by the present waveguide assembly and process.", "Exemplary geometric configurations, as further described below, include waveguide antenna assemblies which encompass, embed or attach to an electronic device coated by a nonconductive, polymeric material.", "Types of electronic device which the present invention may support are as varied as its potential configurations, and include any processor-based systems.", "In particular, devices the present antenna design supports include smartphones, smartwatches and other wearable technology and any devices including GPS or for digitally streaming and broadcasting signals to mobile or desk top systems, including computers and televisions.", "The present invention further provides an underlying process for transceiving of data signals to and from an electronic device supported thereby through a waveguide, comprising transceiving signals of the predetermined frequency range to and from an aperture oriented in a continuous elongated loop formed between conductive layers, wherein the aperture extends into a nonconductive channel so as to electrically isolate the conductive layers to dimensionally support waveguide modes for multimodal transmission and radiation of the signals of a predetermined frequency range, providing a circuit impedance between the two conductive layers for tuning the waveguide mode resonance to form waveguide mode radiation patterns, the circuit impedance of a back short spaced back a corresponding resonant length of the waveguide mode, electromagnetically coupling the signals of a predetermined frequency range to the aperture, by coupling at least one excitation point so as to propagate waveguide mode patterns within the waveguide, and feeding the signals of the predetermined radio frequency range to and from the electronic device supported by the waveguide.", "Reflecting counterpart elements of the assembly, the process further comprises sequentially electromagnetically shifting the waveguide modes to rotationally polarize antenna aperture fields.", "The process enables varying the amplitude and phase coupling of the excitation points to vary waveguide modes and thereby steer antenna gain patterns.", "A process according to the present invention may further comprise steps of encasing an electronic device within the interior of the waveguide assembly or, alternatively, embedding the waveguide antenna in a nonconductive material extending about the electronic device supported thereby.", "A particularly preferred embodiment of the present invention comprises a coaxially disposed inner electrically conductive layer and an outer electrically conductive layer disposed some radial distance about the inner conductive layer, an isolating channel, nonconductive medium, interspersed therebetween and a resonant aperture on the outer electromagnetic interface coextensive with the outer surface of the isolating channel lying between collateral sides of the outer electrically conductive layer circumference and the inner electrically conductive layer outer edges.", "As depicted in the drawings and further specified in the detailed description of the preferred embodiments below, the waveguide comprises conformably looped collaterally, or side-by-side, oriented inner and outer electrically conductive layers form the perimeters of an open ended resonant cavity coextensively interfacing with an electromagnetic aperture formed between respective inner perimeters of the outer conductive layer and the inner conductive layer, a back short spaced apart a resonant distance from the electromagnetic aperture, wherein, and orthogonal excitation points are then strategically oriented in relation to the resonant cavity and set to an amplitude and phase to excite and polarize radio frequency signals received and transmitted through an electromagnetic aperture, thereby propagating waveguide modes.", "As described and claimed herein, the waveguide system and process of the present invention enables excitation and polarization for redirection of antenna radiation patterns, which is commonly known in the art and referred to herein as beam steering, with a single antenna and aperture opening.", "According to the present waveguide antenna system, the inner conductive layer and the outer conductive layer are dimensionally configured to support nonevanescent waveguide modes where the mode resonator is set by spacing the back short from the aperture a resonant length of the nonevanescent waveguide mode wavelength of the signals of the predetermined radio frequency range.", "To thus provide nonevanescent waveguide modes, the back short sets a reference point in the waveguide resonator such that mode fields are stable along the waveguide propagation direction, being at maximum for a mode in the aperture and the excitation point sets the waveguide mode for the resultant aperture field radiation pattern established.", "Thus, the isolating medium occupies the waveguide space that is bounded by the outer and inner conductive layers, and back short conductors.", "In this medium, the waveguide mode resonates and the dominant resonant mode is established by the manner in which the resonant cavity is excited at the feed points.", "In alternative embodiments, the resonant cavity between aperture and back short may be tuned to variable waveguide frequencies.", "In a particularly preferred embodiment, the resonant longitude distance of the resonant cavity between the aperture and the back short is equal to one quarter waveguide wavelength.", "Components of this invention including the-back short, electronically conductive layers, excitation points and isolating medium may comprise material known in the relevant art to be functional or suitable for the stated purpose.", "For example, conductive layers may comprise copper, metal alloys or other well know conductors utilized in prior art antennas, excitation point may employ a printed circuit board (PCB) or microstrip coupling, direct terminals, magnetic loops, or other suitable waveguide launch mechanisms.", "Suitable nonconductive materials to fill the isolating medium include any matter exhibiting low dielectric losses.", "As further alluded to herein, the overall or outer shape of the present waveguide antenna assembly may comprise any geometric configuration which supports aperture field formation and nonevanescent waveguide modes, as described further herein.", "Alternative embodiments may implement shapes that are not radially or cylindrically disposed, such as square, triangular, rectangular or nonsymmetrical or any structure, symmetric or arbitrary capable of supporting nonevanescent multimode behavior.", "Preferred embodiments of the present waveguide antenna are adapted to optimize the aesthetic look and functionality relating to the physical and electronic configuration of a corresponding electronic device in which it is integrated.", "Preferred embodiments of the present waveguide antenna assembly further comprise geometric configurations conforming to and enclosing in body, the outer surface of a wireless device.", "A further preferred embodiment of the present waveguide system strategically orients the continuous aperture to avoid coupling with an electronic device and thereby detuning the antenna.", "In a preferred embodiment of the present invention enabling this feature, the aperture is oriented in a continuous loop contiguously channeled inside the entire outer conductor perimeter.", "Particularly preferred embodiments electronically couple the resonant radio frequencies received and transmitted by the present assembly with the electromagnetic surface waves native to the electronic device with which it is integrated.", "Attributes and properties of the present invention provide many advantages over prior art antennas.", "First, the internal cavity resonator addresses problems related to detuning through coupling with the technology device, so that antenna performance is not impacted, as open resonators (PIFA, loop, etc.) do in compact technology.", "Second, the present waveguide antenna assembly and system is adaptable to the package surface as an efficient surface wave exciter, allowing previously unused package area (outer surface) to render useful in radiation coverage.", "Third, the present invention provides a multimode antenna that can be dynamically configured to redirect the antenna radiation pattern or polarization through a combination of precisely excited waveguide modes.", "Fourth.", "this invention enables radiation redirection, which is commonly referred to in the art as beam steering, by a single antenna resulting from redirection of the mode(s) formed in a single aperture by the excitation points as specified herein, providing a substantial advantage over arrays of multiple antennas required to redirect radiation patterns in the prior art.", "Fifth, the multimode reception of the present waveguide antenna assembly and system allows for coherent integration of the one or more excitation points that can be post processed for noise reduction.", "Sixth, the present waveguide antenna forms an intrinsic EMI barrier, eliminating the need for such shielding.", "A yet further, seventh, advantage provided by the present invention is the minimal physical size of the antenna allowing for more compact designs of modern electronic device.", "Such attributes and properties provide many advantages over prior art antennas.", "An advantage provided by the present invention relates to adaptability of the present waveguide antenna to the exterior surface of an electronic device so as to enhance the resultant radiation pattern.", "For example, where the electronic device is enclosed in a conductive skin that encompasses a rotational surface (i.e., cylinder, tube, etc.), it is possible to establish surface wave propagation on that conductive skin.", "In addition, because the natural mode of propagation is similar in field structure to that established by the aperture field, corresponding surface waves are readily excited.", "Moreover, the adjacent surface of an electronic device may be designed to enhance its interaction with the waveguide antenna to improve those radiation characteristics.", "Substantial advantages provided by the present waveguide antenna assembly and system derive from its compact and versatile geometric configuration.", "Such conformable size and shape render it adaptable for incorporation into condensed designs for wireless electronic devices which are small, sleek, ergonomic, turnkey, portable assemblies and readily secured to a relevant wearable or other surface.", "The present waveguide assembly and system thus delivers enhanced electronic performance within size and configuration confines imposed by such compact electronic devices.", "These and other advantages and benefits heretofore inadequately addressed and unavailable in the prior art are now provided by the waveguide antenna assembly and system as described, enabled and claimed herein.", "BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustrating an exemplary physical configuration of the inner and outer conductive layers, and isolating medium of the present waveguide antenna.", "FIG. 2 is a schematic illustrating a perspective view of the back of a particularly preferred embodiment of the assembled waveguide antenna assembly according to the present invention.", "FIG. 2A is a schematic illustrating perspective view of the front of a particularly preferred embodiment of the assembled waveguide antenna assembly according to the present invention.", "FIG. 2B is a schematic illustrating a perspective view of the front of a particularly preferred embodiment of the disassembled waveguide antenna assembly according to the present invention.", "FIG. 2C is a schematic illustrating a cross sectional view along line 2 D- 2 D of FIG. 2 .", "FIG. 2D is a schematic illustrating a close up view of the circled portion of FIG. 2C labeled SEE 2 D. FIG. 3 is a graphic representation of radially symmetric E and H waveguide mode field lines deployable in the waveguide antenna assembly according to the present invention.", "FIG. 4 is a schematic of a particularly preferred embodiment of the present invention.", "FIG. 4A is a graphic representation of simulated principal plane directivity, gain and polarization isolation patterns for the waveguide antenna assembly of the present invention applied to a wearable GPS of a preferred embodiment.", "FIG. 5 is a schematic of a preferred embodiment of the waveguide assembly and system according to the present invention embedded in an acrylic covered conductive tube of a generally square shape along a transverse axis.", "FIG. 5A is a graphic representation of simulated principal plane directivity and gain patterns for a TEM/H 11 mode switched waveguide antenna assembly of the present invention.", "FIG. 6 is a schematic of a preferred embodiment of the waveguide assembly and system according to the present invention embedded in an acrylic covered conductive tube of a generally rectangular shape.", "FIG. 6A is a graphic representation of simulated principal plane directivity and gain patterns for a fixed H 11 mode waveguide antenna assembly of the present invention.", "DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawings, preferred embodiments and operational details of the present waveguide antenna assembly and system are shown and described in detail.", "In order to more particularly point out and clearly define the presently claimed invention, particularly spatial orientation and electromagnetic correspondence of components of the waveguide assembly, this paragraph defines terms used herein to describe and claim the present invention.", "To that end, dimensional arrangements are defined along Cartesian longitudinal and transverse axes.", "Accordingly, as referred to herein, and well known in the relevant art, a longitudinal direction is parallel to the Cartesian Z axis and the transverse direction parallel to the Cartesian X-Y axis.", "As illustrated, the X-axis is disposed in a horizontal transverse direction and the Y-axis is disposed in a vertical transverse direction.", "The term “collateral”", "as used herein defines spatial orientation electrically conductive layers, claimed as a first conductive layer and as a second conductive layer, to comprise side-by-side alignment not limited to a particular or precise parallel, longitudinal or transverse alignment.", "The collaterally oriented conductive layers are oriented to provide an electrically isolating channel spatially dimensioned to support waveguide modes, which are characterized by corresponding patterns orthogonally depicted along Cartesian axes such as graphically shown in FIG. 3-6A and in the respective detailed descriptions thereof.", "The term “back short”", "is used herein to refer to the physical device that presents the terminating waveguide circuit impedance to the waveguide resonator and this can be formed using any mechanical or electrically controlled feature that presents the proper terminating impedance so that a resonant waveguide mode is established in the waveguide.", "In the preferred embodiment(s) of the present invention, this circuit impedance is a conductive short between the first and second conductive surfaces.", "Illustrating one of innumerable alternative conformable physical configurations and profiles the present waveguide antenna may embody, FIG. 1 exemplifies one irregularly configured preferred embodiment of the present invention.", "The latter structure employs a coaxial waveguide 10 comprising an outer, or first, conductive layer 2 and a collateral inner, or second, conductive layer 4 separated by an isolating channel 6 dimensioned to support nonevanescent waveguide modes.", "Electrically isolating channel 6 may comprise any dielectric or nonconductive medium, and preferably comprises a low loss dielectric material with high permeability, such as, for example, Ba 2 T 19 O 29 or Zr 2 TiO 4 .", "Alternatively, an isolating medium may comprise any suitable low loss material, including for example, air, a vacuum, a dielectric substrate, or a ceramic substrate.", "As particularly pointed out in FIG. 1 , waveguide antenna 10 is conformable to fit about an electronic device (not shown) housed within a hollow or open core 8 formed inside of inner conductive layer 4 .", "Such internal housing of an electronic device within open cavity 8 of waveguide antenna 10 of this preferred embodiment of the present invention, provides multiple advantages.", "First, the conformable, compact assembly is spatially efficient and may be adapted to constrained, variably configured spaces.", "Second, nesting an electronic device within waveguide antenna 10 provides a durable, protective shield about the nested electronic device thereby preventing damage from impacts, and wear and tear.", "Moreover, thus positioning an electronic device within a hollow or open cavity as shown in FIG. 1 overcomes performance problems, such as, detuning, power attenuation, and gain loss issues common to conventional antenna systems and connected electronic devices are juxtapositioned in close proximity.", "In contrast to requisite redesigns of known antennas in order to comply with relevant specifications of new device designs commonly reducing its size and changing the overall profile and configuration, the waveguide antenna of the present invention may be readily adapted without comparable redesigning.", "The present waveguide antenna's resistance to performance impediments and concomitant conformability to package redesigns of electronic devices provides substantial improvements over prior art antenna configurations.", "FIG. 2-2D illustrate a preferred embodiment of the present waveguide antenna assembly 20 comprising a generally square configuration particularly designed for use in the many electronic devices employing GPS.", "FIG. 2 shows a perspective view from the back of the waveguide antenna assembly 20 showing connectors 28 for feeding data signals to an electronic device through techniques well known in the art.", "FIG. 2A depicts a frontal perspective view of waveguide assembly 20 showing orientation of excitation points 24 on microstrip PCA 26 , when assembled to cover aperture 12 , which electromagnetically transceives signals of a predetermined frequency range through microstrip PCA 26 .", "FIG. 2B shows microstrip PCA 26 disassembled from the waveguide antenna assembly 20 to reveal orientation of aperture 12 relative to quadrature orthogonal excitation points 24 .", "Now referring to FIG. 2B-2D , aperture 12 opens into isolating channel 18 providing an isolating cavity resonator for transmission of waveguide modes from which the impedance of back short 22 is set in connection with quadrature excitation points 24 so as to form nonevanescent waveguide modes.", "FIGS. 2C and 2D are cross-sectional views of the particularly preferred embodiment of FIG. 2 - FIG. 2B showing a cutaway view taken along line 2 D- 2 D. FIG. 2D provides an exploded view of the area circled in FIG. 2C more clearly depicting the geometric configuration and relative orientation of aspects enabling the electromagnetic synchrony of the present waveguide antenna.", "As shown in FIGS. 2C and 2D cross sectional views of outer, or first, conductive layer 14 and inner, or second, conductive layer 16 are separated and thereby isolated by electrically isolating channel 18 , which may comprise any dielectric.", "Electrically isolating channel 18 opens into aperture 12 , which electromagnetically forms aperture fields of the signals of a predetermined radio frequency range through electrical coupling with excitation points 24 that is part of the microstrip PCA 26 with dielectric substrate 23 and reference ground plane 21 and back short 22 , as described below.", "Aperture 12 is spaced a resonant one quarter waveguide mode wavelength of the corresponding signals of the predetermined radio frequency range from back short 22 , Back short 22 provides a circuit impedance between the first conductive layer and the second conductive layer whereby the waveguide is tuned to the signals of a predetermined frequency range.", "In the particularly preferred embodiment shown in FIG. 2-2D , each excitation point 24 is individually controlled by dynamic amplitude and phase positioning resulting in waveguide modes which are preferably nonevanescent.", "Excitation points 24 are phased to establish orthogonal modes which rotate aperture fields either clockwise or counter clockwise.", "Thus, quadrature excitation points 24 are amplitude and phase coupled so as to alter waveguide modes, thereby steering antenna gain pattern of the radio frequency signals of a predetermined wavelength.", "As detailed in FIG. 3-6A and respective description thereof, adjusting amplitude and phase rotates the aperture field about a symmetrical longitudinal axis to dynamically control the radiation polarization orientation to a horizontal, vertical or any angle therebetween.", "Exemplary modes established by arranging field excitations to align with the mode's field pattern are graphically represented in FIG. 3 .", "Skilled artisans will further recognize the modes graphically shown in FIG. 3 depict a static phase relationship, as utilized in the waveguide of the present invention, wherein excitation points generate field distribution lines forming the illustrated mode patterns.", "As marked to the right of the respective planes of waveguide mode patterns in FIG. 3 , appropriate order modes are marked, as follows: 1.", "cross sectional view, 2.", "longitudinal view, and 3.", "surface view along a coaxial waveguide from Cartesian axes as defined above and shown in the planes identified by the X, Y, and Z axes as shown in the drawings and referred to herein.", "Now referring to FIG. 3 , H modes 30 are shown in the left column and E mode patterns 40 are shown on the right column.", "In particular, H order waveguide mode transverse magnetic field lines 34 A, 34 B, and 34 C respectively depict H 11 , H 21 and H 31 order modes cut along a plane transverse to the direction of propagation.", "Longitudinal lines 36 A, 36 B, and 36 C depict the same mode patterns for H 11 , H 21 and H 31 order modes cut along longitudinal planes corresponding to respective lines A 3 -A 3 , B 3 -B 3 , C 3 -C 3 in the direction of propagation.", "Surface patterns 38 A, 38 B and 38 C depict views from points A/A, B/B.", "and C/C counterpart perspectives of E order waveguide modes 40 field distribution lines which may be harnessed in the waveguide of the present invention are graphically depicted on the right half of FIG. 3 .", "In particular, transverse magnetic field lines 44 A, 44 B, and 44 C depict the relevant mode patterns transverse to the direction of propagation for E 11 , E 21 , and E 31 order modes respectively while 46 A, 46 B and 46 C illustrate respective longitudinal pattern cut along lines D 3 -D 3 , E 3 -E 3 , and F 3 -F 3 , and patterns 48 A, 48 B, and 48 C depict patterns from points D/D, E/E, and F/F respectively.", "Modes within the scope of the present invention include, but are not limited to, those shown in FIG. 3 , which are exemplary waveguide mode patterns.", "Although not included in FIG. 3 , it will be apparent to persons skilled in the art that TEM is supported by the present waveguide assembly.", "That is, by strategically orienting positive voltage terminals on an electrically conductive layer, which may be inner or outer layers if a coaxial waveguide, relative to diametrically opposing excitation point, resultant excitation electric field strongly couples to the TEM mode, rejecting modes that are not field aligned.", "In contrast to radially symmetric TEM modes utilized in conventional antenna systems, the strategic orientation and amplitude/phase coordination provided by application of evanescent mode forms as the primary aperture field distribution provides substantial advantages.", "To demonstrate the dynamic correspondence providing such advantages, the following calculations will make apparent to persons skilled in the relevant art the electromagnetic rotation providing the phase shifting enabled by the present invention.", "As well known in the art, the waveguide mode with the lowest cutoff frequency is the basic mode of the waveguide, and its cutoff frequency is the waveguide cutoff frequency.", "Accordingly, the cutoff wavelength for the E and H modes are: λ_ cE≈ 2( a−b )/ n,E —mn modes, m= 0,1, .", "n>", "0 (1) λ_ cH ≈π( a+b )/ m,H —m1 modes, m= 1,2, (2) where a and b are the radial symmetric waveguide inner and outer conductor respective radii.", "Examination of the guide cutoff wave length(s), show that for large radius and small conductor separation, the probable set of modes is only the H —m1 .", "Furthermore, those H —m1 modes can be excited by selectively placing excitation points rotationally at: (π( i− 1))/ m,i= 1,2, .", "m+ 1 The present waveguide antenna system uses this arrangement to selectively excite the radially symmetric TEM, or the higher order asymmetric H —m1 modes.", "FIG. 4 depicts a particularly preferred embodiment of the present waveguide antenna assembly, contemplated as a deployable GPS antenna 50 for small wearable electronic devices, such as a smart watch.", "The overall geometric configuration of GPS antenna 51 is generally a square measuring 25 mm×25 mm×5 mm high and placed on the body wrist 53 .", "This embodiment sets excitation points, counterparts of which are shown in FIG. 2 , with equal amplitudes and sequentially phase shifts each by 90 degrees whereby right hand polarization, such as graphically depicted in FIG. 5 , is exhibited.", "Now referring to FIG. 4A , a graph depicting the radiation pattern conveys how multimode properties of the present waveguide antennae may be implemented to control, or shift, the radiation pattern.", "In particular, by exciting orthogonal H modes in quadrature phase, the radiation pattern will form an Omni Right Hand Circular Polarization (RHCP) pattern graphed by dashed and dotted line 52 and solid line 54 and suppress the Left Hand Circular Polarization (LHCP) graphed by dotted line 56 and broken dashed and dotted line 58 , and thereby optimize GPS signal reception.", "As used herein, quadrature phase refers to: excitation of the feeds by sequentially shifting each feed phase by 90 degrees relative to the feed before with equal amplitudes.", "Referring to FIG. 5 , an alternative preferred embodiment of the present invention is provided in a conductive tube 60 covered by an acrylic or other low loss dielectric wherein a multimode coaxial waveguide antenna 62 is embedded which houses an electronic device.", "Such a nonconductive or low loss material could comprise, for example, a polymeric material such as an acrylic, an epoxy, a phenolic, baked glass, or ceramic compound.", "FIG. 5A provides a graphic representation of simulated principal plane directivity and gain patterns for a TEM/H 11 mode switched waveguide antenna assembly of the present invention.", "The graphic data shown in FIG. 5A demonstrates antenna gain patterns relating to excitation switching, i.e., suppression or enhancement thereof, between the TEM and H 11 modes whereby mode propagation is controlled, that determines the antenna radiation in a bore sight direction along the XZ plane, or along a broadside direction along the YZ plane.", "Thus, the excitation points may be manipulated to switch from a bore sight to broadside directions or eliminate interference from either direction, which is otherwise known in the art and referred to herein as beam steering.", "In the latter embodiment, the radiation patterns in the generally square configuration shown in FIG. 5A graphically depict improved gain provided by stable excitation of nonevanescent H 11 /TEM patterns graphically depicted, along the XZ plane of FIG. 5 , as dashed line 64 and dotted line 70 , respectively, and as dashed and dotted line 68 and solid line 66 along the XY plane.", "FIG. 6 illustrates a further preferred embodiment employing a generally rectangular configuration 80 of the present invention to further exemplify the flexibility of the parameters of potential embodiments of the present invention.", "In this embodiment, antenna 82 is scaled approximately three times in the Y dimension and half the X dimension (75 mm×12 mm vs 25 mm×25 mm).", "All other parameters remain the same as in FIG. 5 .", "FIG. 6A provides a graphic representation of simulated principal plane directivity and gain patterns for a H 11 mode.", "Corresponding waveguide mode patterns depicted by solid line 84 shows the H 11 mode along the XZ plane and dashed and dotted line 86 shows the H 11 mode along the XY plane.", "A comparison of FIG. 5A and FIG. 6A demonstrates that substantial modification of antenna dimensions as shown in respective configuration shown in FIG. 5 and FIG. 6 has minimal impact on the antenna performance—XZ plane peak gain @ angle=delta<ldB.", "Such dimensional conformability of the present waveguide antenna manifests in diverse space allocations and applications, and is particularly advantageous in compact electronic device package redesigns contexts.", "The present waveguide antenna's stable performance notwithstanding packaging revisions while maintaining provides a substantial advantage of the present waveguide antenna over existing designs wherein package reconfiguration typically requires complete redesign of supporting antenna(s).", "While a number of exemplary aspects and embodiments have been discussed above, those possessed of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof.", "In particular, this invention embraces waveguides of any shape and size, regardless of symmetry or geometric regularity, wherein dynamic positioning of an aperture in correspondence with a resonant back short and excitation points configured to provide nonevanescent waveguide modes described and claimed herein.", "Such waveguides are not limited to a coaxial configuration but may comprise any number or combination of conductive layers and resonant cavities.", "It is therefore intended that the scope of this specification include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope." ]